Inductance measurement device and inductance measurement method

Abstract

This inductance measurement device (1) applies an AC voltage (Vuvw) to an inductive load (2) by means of a power conversion unit (3), and measures the inductance (Lm) of the load (2) based on a calculation using the detected value of a phase current of the load (2) and a voltage command (sgc). A control unit (4) calculates the voltage command (sgc) by which the AC voltage (Vuvw) is applied to the load (2), controls the power conversion unit (3) on the basis of the voltage command (sgc) and a carrier signal (51), and detects the phase current of the load (2) by a direct current (Idc) detected by the current detection unit (5) during the control of the power conversion unit (3). On the basis of the change tendency of the carrier signal (51) before and after a timing (Tsr) at which the polarity of the voltage command (sgc) or the AC voltage (Vuvw) is reversed, the control unit (4) determines whether to detect the phase current of a detection target phase (Pid) in a voltage unit interval (Tru) before or after the timing (Tsr).

Description

Inductance measuring device and inductance measuring method

[0001] The present disclosure relates to an inductance measurement device and an inductance measurement method.

[0002] For inductive loads such as rotating machines, it is desirable to know the electrical constants of the inductive load, such as its resistance and inductance. In particular, when driving a permanent magnet synchronous motor, which is an inductive load, without using a position sensor to detect the magnetic pole position, the electrical constants of the inductive load are necessary.

[0003] Patent Document 1 discloses a method for measuring the inductance of a rotating machine, i.e., a method for measuring the inductance of a rotating machine. The inductance measurement method of Patent Document 1 applies a three-phase high-frequency rotating voltage to the rotating machine, and measures the inductance based on the current flowing through the rotating machine, i.e., the frequency components identical to the high-frequency voltage contained in the rotating machine current of each phase, and the effective value and frequency of the high-frequency rotating voltage. The inductance measurement method of Patent Document 1 requires the use of a current sensor or the like to detect the three-phase rotating machine current flowing through the rotating machine.

[0004] As a method for detecting three-phase rotating machine currents flowing through a rotating machine, a "single-shunt current detection method" is known, as described in the background art of Patent Document 2. A control device that drives and controls a rotating machine may have a power conversion unit such as an inverter that converts a DC voltage supplied from a DC power source into a three-phase AC voltage to be applied to the rotating machine. The single-shunt current detection method detects two phases of the three-phase rotating machine current based on a DC bus current flowing between the DC power source and the power conversion unit, and calculates the remaining one phase of current from the detected two phases of current using Kirchhoff's law. In the single-shunt current detection method, the DC bus current is converted into the rotating machine current based on the switching state of switching elements that constitute the power conversion unit.

[0005] International Publication No. 2012 / 077153 Japanese Patent Application Laid-Open No. 2021-164320

[0006] When measuring the inductance of a rotating machine using the rotating machine current as in Patent Document 1, accurate inductance measurement requires accurate detection of the peak value of the rotating machine current, i.e., the peak current value. When a high-frequency voltage, i.e., an AC voltage, is applied to the rotating machine, the time resolution of the inverter output voltage decreases relatively depending on the calculation period and carrier frequency. In the single-shunt current detection method, a voltage vector applied to the rotating machine is required to be suitable for detecting the rotating machine current of each phase, i.e., the phase current. However, depending on the waveform and frequency of the AC voltage, an appropriate voltage vector may not appear. In this case, a detection voltage vector must be inserted to detect the phase current. On the other hand, if a current detection command for current detection is inserted into the command to the inverter to insert the detection voltage vector into the AC voltage, the decrease in the time resolution of the inverter output voltage can result in a large voltage disturbance and significant current distortion.

[0007] An object of the present disclosure is to detect peak current with high accuracy when measuring the inductance of an inductive load by applying an AC voltage.

[0008] The inductance measurement device according to the present disclosure is a device that applies an AC voltage to an inductive load to measure the inductance of the inductive load. The inductance measurement device includes a power conversion unit that receives DC power as input and converts it using multiple switching elements to supply the AC power to the inductive load, a current detection unit that detects a current flowing through a DC terminal of the power conversion unit, and a control unit that calculates a voltage command for the AC power applied to the inductive load, controls the power conversion unit using switching commands to the switching elements calculated based on the voltage command and a carrier signal, and detects a phase current of the inductive load using the DC current detected by the current detection unit while the power conversion unit is being controlled by the switching command. The inductance measurement device is configured to calculate the inductance of the inductive load based on the detected value of the phase current and the voltage command. The vertices that are maximum and minimum values ​​in the carrier signal are defined as first and second vertices, respectively, and the section between the adjacent first and second vertices is defined as a voltage unit section. The voltage command or the AC voltage applied to the inductive load is set as the sign determination target, the timing at the end of the voltage unit interval when the sign of the target to be determined is set as the sign reversal timing, and the phase of the AC voltage whose sign is reversal at the sign reversal timing is set as the target phase of the phase current to be detected.The control unit determines, based on the change tendency of the carrier signal before and after the sign reversal timing, to detect the phase current of the target phase in the voltage unit interval before the sign reversal timing or in the voltage unit interval after the sign reversal timing.

[0009] According to the inductance measuring device of the present disclosure, the control unit determines whether to detect the phase current of the phase to be detected in the voltage unit interval before or after the sign reversal timing, based on the change trend of the carrier signal before and after the sign reversal timing. Therefore, when applying an AC voltage to measure the inductance of an inductive load, the peak current can be detected with high accuracy.

[0010] 1 is a diagram showing an example of a configuration of an inductance measurement device according to a first embodiment. FIG. 1 is a diagram showing another example of the DC power supply of FIG. 1. FIG. 1 is a diagram showing an example of a configuration of a power conversion unit of FIG. 1. FIG. 1 is a diagram showing an example of a configuration of a control unit of FIG. 1. FIG. 2 is a diagram showing a first example of an AC voltage applied to an inductive load. FIG. 3 is a diagram showing a second example of an AC voltage applied to an inductive load. FIG. 4 is a diagram showing a third example of an AC voltage applied to an inductive load. FIG. 5 is a diagram showing a fourth example of an AC voltage applied to an inductive load. FIG. 6 is a diagram showing a first example of a carrier signal of the inductance measurement device of FIG. 1. FIG. 7 is a diagram showing an example of an on-off signal of FIG. 1. FIG. 8 is a diagram explaining a DC bus current detected by a current detection unit of FIG. 1. FIG. 9 is a diagram showing an example of pulse shift processing by a voltage command adjustment unit and a PWM signal generation unit of FIG. 4. FIG. 10 is a diagram showing a pulse end difference and a current detection time of an on-off signal according to the first embodiment. FIG. 11 is a diagram showing a pulse end difference and a current detection time of an on-off signal according to the first embodiment. FIG. 12 is a diagram showing an example of pulse shift processing by a voltage command adjustment unit and a PWM signal generation unit of FIG. 4. FIG. 13 is a diagram showing an example of a phase voltage and a phase current of the rotating machine of FIG. 1. 26 is a diagram showing a first example of a voltage command of the inductance measurement device and a phase current of the rotating machine of FIG. 1 . FIG. 27 is a diagram showing a first example of current detection timing in the first current detection period of FIG. 18 . FIG. 28 is a diagram showing an example of current detection timing in a period after the first current detection period of FIG. 18 . FIG. 29 is a diagram showing a second example of a voltage command of the inductance measurement device and a phase current of the rotating machine of FIG. 1 . FIG. 29 is a diagram showing an example of current detection timing in a period before the third current detection period of FIG. 21 . FIG. 29 is a diagram showing an example of current detection timing in the third current detection period of FIG. 21 . FIG. 29 is a diagram showing an example of current detection timing in the second current detection period of FIG. 18 . FIG. 29 is a diagram showing an example of current detection timing in the fourth current detection period of FIG. 21 . FIG. 30 is a diagram showing a third example of a voltage command of the inductance measurement device and a phase current of the rotating machine of FIG. 1 . FIG. 27 is a diagram showing an example of current detection timing in the first carrier period of FIG. 26 . FIG. 31 is a diagram showing a fourth example of a voltage command of the inductance measurement device and a phase current of the rotating machine of FIG. 1 . FIG. 28 is a diagram showing an example of current detection timing in the second carrier period of FIG. 28 . FIG. 32 is a diagram showing a second example of current detection timing in the first current detection period of FIG. 18 .37 is a diagram showing an example of a voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 2. FIG. 38 is a diagram showing a first example of current detection timing in the first carrier period of FIG. 31 . FIG. 39 is a diagram showing an example of current detection timing in the second carrier period of FIG. 31 . FIG. 40 is a diagram showing a second example of current detection timing in the first carrier period of FIG. 31 . FIG. 41 is a diagram showing an example of voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 3. FIG. 42 is a diagram showing an example of current detection timing in the third carrier period of FIG. 35 . FIG. 41 is a diagram showing an example of voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 4. FIG. 38 is a diagram showing an example of current detection timing in the first carrier period of FIG. 37 . FIG. 41 is a diagram showing an example of a configuration of a control unit of an inductance measurement device according to embodiment 5. FIG. 42 is a diagram showing a first example of voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 5. FIG. 43 is a diagram showing an example of current detection timing in the third carrier period of FIG. 40 . FIG. 43 is a diagram showing a second example of voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 5. FIG. 44 is a diagram showing an example of current detection timing in the first carrier period of FIG. 44 . 39 is a diagram showing a third example of a voltage command and a phase current of a rotating machine in the inductance measurement device according to embodiment 5. FIG. 39 is a diagram showing a positive side peak correction time of the timing determination unit of FIG. 39. FIG. 39 is a diagram showing a negative side peak correction time of the timing determination unit of FIG. 39. FIG. 39 is a diagram showing an example of a hardware configuration that realizes the functions of a control unit by digital calculation. FIG. 40 is a diagram showing the main parts of a control unit according to embodiments 3 and 4.

[0011] Embodiment 1. FIG. 1 is a diagram showing an example of the configuration of an inductance measurement device according to embodiment 1, and FIG. 2 is a diagram showing another example of the DC power supply of FIG. 1. FIG. 3 is a diagram showing an example of the configuration of the power conversion unit of FIG. 1, and FIG. 4 is a diagram showing an example of the configuration of the control unit of FIG. 1. FIGS. 5, 6, 7, and 8 are diagrams showing first, second, third, and fourth examples of AC voltages applied to an inductive load, respectively. FIGS. 9 and 10 are diagrams showing first and second examples of carrier signals of the inductance measurement device of FIG. 1, respectively. FIG. 11 is a diagram showing an example of an on / off signal of FIG. 1, and FIG. 12 is a diagram explaining the DC bus current detected by the current detection unit of FIG. 1. FIG. 13 is a diagram showing an example of pulse shift processing by the voltage command adjustment unit and PWM signal generation unit of FIG. 4. FIGS. 14 and 15 are diagrams showing the pulse end difference and current detection time of the on / off signal according to embodiment 1, respectively. FIG. 16 is a diagram showing an example of pulse shift processing by the voltage command adjustment unit and PWM signal generation unit of FIG. 4. FIG. 17 is a diagram showing an example of the phase voltage and phase current of the rotating machine of FIG. 1 , and FIG. 18 is a diagram showing a first example of the voltage command of the inductance measurement device of FIG. 1 and the phase current of the rotating machine. FIG. 19 is a diagram showing a first example of current detection timing in the first current detection period of FIG. 18 , and FIG. 20 is a diagram showing an example of current detection timing in the period after the first current detection period of FIG. 18 . FIG. 21 is a diagram showing a second example of the voltage command of the inductance measurement device of FIG. 1 and the phase current of the rotating machine. FIG. 22 is a diagram showing an example of current detection timing in the period before the third current detection period of FIG. 21 , and FIG. 23 is a diagram showing an example of current detection timing in the third current detection period of FIG. 21 . FIG. 24 is a diagram showing an example of current detection timing in the second current detection period of FIG. 18 , and FIG. 25 is a diagram showing an example of current detection timing in the fourth current detection period of FIG. 21 . FIG. 26 is a diagram showing a third example of the voltage command of the inductance measurement device of FIG. 1 and the phase current of the rotating machine, and FIG. 27 is a diagram showing an example of current detection timing in the first carrier period of FIG. 26 . 28 is a diagram showing a fourth example of the voltage command of the inductance measuring device of FIG. 1 and the phase current of the rotating machine, and FIG. 29 is a diagram showing an example of the detection timing of the current in the second carrier period of FIG. 28.Fig. 30 is a diagram showing a second example of current detection timing in the first current detection period of Fig. 18. The inductance measurement device 1 of embodiment 1 is connected to a DC power supply 6, and includes a power conversion unit 3 that converts DC power to AC power and supplies the AC power to an inductive load such as a rotating machine 2, a control unit 4 that controls the operation of the power conversion unit 3, and a current detection unit 5. Here, the inductive load will be described using a rotating machine as an example.

[0012] The inductance measurement device 1 of the first embodiment is a device that measures the inductance Lm of an inductive load by applying an AC voltage such as a three-phase voltage Vuvw to the inductive load, and is configured to receive DC power as input, convert the converted AC power by a power conversion unit 3, supply the converted AC power to the inductive load, and calculate the inductance Lm of the inductive load based on the DC current flowing through DC terminals 13n, 13p of the power conversion unit 3 detected by a current detection unit 5. In FIG. 1 , a rotating machine 2 is shown as an example of the inductive load. The inductance measurement device 1 includes an operation mode switching unit 38 that switches the operation mode of the control unit 4, and functions as a control device for the inductive load when driving an inductive load such as the rotating machine 2.

[0013] The control unit 4 controls the power conversion unit 3 with an on / off signal sg2 based on the carrier signal 51 and a three-phase voltage command sgc. The current detection unit 5 detects a DC bus current Idc, which is a DC current flowing through DC terminals 13p and 13n of the power conversion unit 3. The DC power supply 6 outputs DC power to the power conversion unit 3, and supplies power to the rotating machine 2 via the power conversion unit 3. The DC power supply 6 is, for example, a storage battery or a power conversion device configured to convert AC power to DC power, as shown in FIG. 2 . FIG. 2 shows an example of the DC power supply 6 that converts AC power from an AC power supply 8, which is a single-phase power supply or a three-phase power supply, into DC power using a rectifier 9. A positive power supply terminal 17p of the DC power supply 6 is connected to a positive DC terminal 13p of the power conversion unit 3 via a positive DC bus 18p. A negative power supply terminal 17n of the DC power supply 6 is connected to a negative DC terminal 13n of the power conversion unit 3 via a negative DC bus 18n.

[0014] The rotating machine 2 is, for example, an AC motor or a brushless DC motor. The rotating machine 2 has a rotor and a stator (not shown). The stator has three-phase windings: U-phase, V-phase, and W-phase. The rotor is provided with a permanent magnet.

[0015] The current detection unit 5 detects a DC bus current Idc flowing between the DC power supply 6 and the power conversion unit 3. The current detection unit 5 is, for example, a current sensor using a shunt resistor.

[0016] The location of the current detection unit 5 is not limited to the location shown in Fig. 1. For example, the current detection unit 5 may be provided inside the power conversion unit, or may be provided on the DC bus 18p between the DC power supply 6 and the power conversion unit 3 on the positive side of the DC power supply 6.

[0017] Next, the configuration of the power conversion unit 3 will be described with reference to FIG. 3 . For example, the power conversion unit 3 is an inverter 10. The switching elements 11a to 11f of the power conversion unit 3 form a full-bridge circuit. The switching elements 11a, 11c, and 11e connected to the high-voltage side wiring 14p form an upper arm, and the switching elements 11b, 11d, and 11f connected to the low-voltage side wiring 14s form a lower arm. The three legs, each formed by connecting the upper arm and the lower arm in series, are a U-phase series body formed by connecting the switching element 11a and the switching element 11b in series, a V-phase series body formed by connecting the switching element 11c and the switching element 11d in series, and a W-phase series body formed by connecting the switching element 11e and the switching element 11f in series. The connection point between the upper arm and the lower arm is connected to an AC terminal. The connection point n1 between the switching element 11a and the switching element 11b is connected to the AC terminal 12u. A connection point n2 between switching element 11c and switching element 11d is connected to AC terminal 12v, and a connection point n3 between switching element 11e and switching element 11f is connected to AC terminal 12w. In FIG. 3, an example is shown in which the switching elements 11a to 11f are configured with an insulated gate bipolar transistor (IGBT) serving as a transistor Tr and a diode Di connected in anti-parallel to the IGBT. The switching elements 11a to 11f are not limited to this configuration and may be metal oxide semiconductor field effect transistors (MOSFETs) having a transistor Tr and a diode Di. The diode Di may be a parasitic diode of the MOSFET or a separate diode.

[0018] An on / off signal sg2 is input from the control unit 4 to the power conversion unit 3 to determine the switching state, i.e., the on state or off state, of each of the switching elements 11a to 11f. The on / off signal sg2 includes a predetermined dead time to prevent the series-connected switching elements of the power conversion unit 3 from being simultaneously turned on. On / off signals Up2, Vp2, and Wp2 are input to control terminals of the switching elements 11a, 11c, and 11e, respectively. On / off signals Un2, Vn2, and Wn2 are input to control terminals of the switching elements 11b, 11d, and 11f, respectively. Where appropriate, the on / off signals will be referred to collectively as sg2, and will be referred to as Up2, Un2, Vp2, Vn2, Wp2, and Wn2 when distinguishing between them. The power conversion unit 3 converts the DC bus voltage Vdc into a desired three-phase voltage Vuvw and supplies it to the rotating machine 2 by switching the switching states of the switching elements 11a to 11f based on the on / off signal sg2.

[0019] Examples of the three-phase voltage Vuvw supplied from the power conversion unit 3 to an inductive load such as a rotating machine 2 are shown in FIGS. 5 to 8 . FIG. 5 shows three-phase voltage waveforms 45a, 45b, and 45c output from the power conversion unit 3 when the voltage command sgc is a sine wave command. FIG. 6 shows three-phase voltage waveforms 45a, 45b, and 45c output from the power conversion unit 3 when the voltage command sgc is a square wave command. When the phase voltage waveforms 45a, 45b, and 45c are square waves, the fundamental wave component is increased compared to when the sine wave command is used, increasing the maximum voltage value and the current, thereby expanding the range of inductance measurement conditions. Note that the inductance value varies with the current. While FIGS. 5 and 6 show examples in which the phases are shifted by 120°, the three-phase voltage Vuvw may also be the alternating voltage shown in FIG. 7 or the alternating rectangular voltage shown in FIG. 8. 7 shows an example of an alternating voltage in which phase voltage waveform 45a is the reference phase and phase voltage waveforms 45b and 45c are -0.5 times the reference phase. FIG. 8 shows an example of an alternating rectangular voltage in which phase voltage waveform 45a is the reference phase and phase voltage waveforms 45b and 45c are -0.5 times the reference phase. Depending on the type of rotating machine (motor), inductance measurement may be performed using an alternating voltage or an alternating rectangular voltage. Since the inductance measurement device 1 of embodiment 1 can use an alternating voltage in addition to three-phase AC, it can measure inductance regardless of the type of rotating machine (motor).

[0020] Of the voltage vectors, which are combinations of three-phase voltages output by the power conversion unit 3, a voltage vector output when the upper arms of all phases are in the ON state and the lower arms of all phases are in the OFF state and a voltage vector output when the upper arms of all phases are in the OFF state and the lower arms of all phases are in the ON state are sometimes called zero-voltage vectors.Furthermore, of the voltage vectors output by the power conversion unit 3, a voltage vector output when the upper arm of one phase and the lower arms of the other two phases are in the ON state and a voltage vector output when the upper arms of two phases and the lower arm of the other one phase are in the ON state are sometimes called non-zero-voltage vectors.

[0021] 1 , when the DC bus current Idc is detected by a current detection unit 5 having a shunt resistor, that is, when the DC bus current Idc is detected by a one-shunt current detection method, the DC bus current Idc becomes zero when a zero voltage vector is applied to the rotating machine 2, and the DC bus current Idc does not become zero when a non-zero voltage vector is applied to the rotating machine 2. In the present disclosure, a set of on / off signals sg2 of the multiple switching elements 11a to 11f based on the three-phase voltage command sgc that makes the DC bus current Idc zero is defined as a zero voltage vector, and a set of on / off signals sg2 of the multiple switching elements 11a to 11f based on the three-phase voltage command sgc that makes the DC bus current Idc zero is defined as a non-zero voltage vector.

[0022] The control unit 4 includes a phase current output unit 31, a voltage command calculation unit 32, a voltage command adjustment unit 39, a PWM signal generation unit 33, a timing determination unit 35, an adjustment amount determination unit 36, an inductance calculation unit 37, and an operation mode switching unit 38. Various functions of the control unit 4 are realized by a calculation device such as a microcomputer executing software. The functions realized by the digital calculations of the control unit 4 may be realized by a processor 108 and a memory 109, as shown in FIG. 48 . FIG. 48 is a diagram showing an example of a hardware configuration in which the functions of the control unit are realized by digital calculations. In this case, the functions realized by the digital calculations of the control unit 4 are realized by the processor 108 executing a program stored in the memory 109. Alternatively, multiple processors 108 and multiple memories 109 may cooperate to execute each function. Alternatively, the control unit 4 may be configured with hardware such as circuits and devices that realize each function.

[0023] The operation mode switching unit 38 switches the operation mode of the control unit 4 based on the operation mode signal sgm. The operation modes of the control unit 4 include, for example, a rotating machine drive mode Md1 for normal operation, such as driving the rotating machine 2 at a desired speed, and an inductance measurement mode Md2 for measuring the inductance Lm of the rotating machine 2. When there are two operation modes, the operation mode signal sgm is a 1-bit digital signal. For example, when the operation mode signal sgm is 0, the rotating machine drive mode Md1 is selected, and when the operation mode signal sgm is 1, the inductance measurement mode Md2 is selected. The operation mode switching unit 38 may switch the operation mode based on the result of calculation by the control unit 4, or may switch the operation mode based on information from an external sensor (not shown) input to the control unit 4 or a signal input from a higher-level control device (not shown).

[0024] The control unit 4 transitions to the inductance measurement mode Md2 at any timing. The timing to transition to the inductance measurement mode Md2 may be determined by a device external to the control device, such as a higher-level control device, or may be determined by the control unit 4 itself based on a signal input to the control unit 4.

[0025] The inductance calculation unit 37 is activated upon transition to the inductance measurement mode Md2, and calculates the inductance Lm using the effective value and average value of the voltage command sgc calculated by the voltage command calculation unit 32 (described later) or the effective value and average value of the three-phase voltage Vuvw output by the power conversion unit 3 to the rotating machine 2, and the three-phase current Iuvw output by the phase current output unit 31. The voltage command sgc and the three-phase voltage Vuvw in the inductance measurement mode Md2 are voltages that generate an AC current in the rotating machine 2, i.e., high-frequency voltages, and may have any AC waveform including a fundamental wave that is a sine wave or a cosine wave, a rectangular wave, or the like. The AC waveforms of the voltage command sgc and the three-phase voltage Vuvw when measuring the inductance Lm of the rotating machine 2 are not limited to a fundamental wave and may include harmonics as long as the frequency of the main fundamental wave component is sufficiently high. Here, an AC waveform including a fundamental wave that is a sine wave or a cosine wave, or a rectangular wave, is defined as a quasi-fundamental wave. By increasing the frequency of the high-frequency voltage applied to the rotating machine 2, if the inductive load is the rotating machine 2, the rotating machine 2 becomes less likely to rotate, thereby improving the measurement accuracy of the inductance Lm. An inductance measurement method is described, for example, in Patent Document 1. Patent Document 1 describes in detail the method and principle of calculating the inductance based on the high-frequency voltage command and the phase current of the rotating machine, so a description of the method and principle of calculating the inductance Lm of the rotating machine 2 will be omitted here. Note that FIG. 4 shows an example in which the voltage command sgc and the three-phase current Iuvw are input to the inductance calculation unit 37.

[0026] The phase current output unit 31 outputs a three-phase current Iuvw, which is a three-phase current flowing through the rotating machine 2, based on the DC current (DC bus current Idc) detected by the current detection unit 5. More specifically, the phase current output unit 31 detects two phase currents in the three-phase current Iuvw, which is a three-phase current, using a single-shunt current detection method based on the DC bus current Idc detected by the current detection unit 5 at a detection timing Tg input from the timing determination unit 35. Information on the detection timing Tg is included in a detection timing signal sgs. The DC bus current Idc reflects the phase currents flowing through the power conversion unit 3, which operates based on the on / off signals sg2 for each phase. The phase currents of the U phase, V phase, and W phase are Iu, Iv, and Iw, respectively. The phase current output unit 31 detects the phase currents for two of the three phase currents from the DC bus current Idc, and then calculates the current for the remaining phase from the detected phase currents for the two phases using Kirchhoff's law.

[0027] When the voltage command calculation unit 32 transitions to the inductance measurement mode Md2, it calculates, as a voltage command sgc to the power conversion unit 3, a voltage command vector Vuvw* in which the phase voltages Vu, Vv, and Vw of each phase of the three-phase voltage Vuvw, which is the output voltage of the power conversion unit 3, are quasi-fundamental. When measuring the inductance Lm of the rotating machine 2, the voltage command adjustment unit 39 adjusts a fundamental voltage command 119 (see FIG. 18 ), which is a three-phase voltage command sgc that causes each of the three-phase voltages supplied to the rotating machine 2 to generate a fundamental current in the rotating machine 2, to generate a three-phase adjusted voltage command sgca including a current detection command 120 (see FIG. 19 ). The quasi-fundamental output voltage is a voltage that generates a fundamental current in the rotating machine 2. The fundamental current is, for example, the phase current waveform 47 shown in FIG. 17 or the rotating machine current Im shown in FIG. 18 . The phase current waveform 47 shown in FIG. 17 is a sine or cosine waveform that does not include high-frequency components such as noise. The waveform of the rotating machine current Im shown in Fig. 18 is also slightly distorted due to noise, etc., but has the same periodicity and change tendency as the phase current waveform 47 shown in Fig. 17. The rotating machine current Im shown in Fig. 18 is also a fundamental wave current. The voltage waveform of the quasi-fundamental wave when the quasi-fundamental wave is a rectangular wave is shown in Fig. 6. The three-phase voltage Vuvw supplied to the rotating machine 2 corresponds to a high-frequency voltage, and the fundamental voltage command 119 corresponds to a high-frequency voltage command.

[0028] More specifically, the phase voltages Vu, Vv, and Vw in the inductance measurement mode Md2 have a fundamental frequency of fh and a fundamental effective value of Vh. The U-phase, V-phase, and W-phase components of the voltage command vector Vuvw* are voltage commands Vu*, Vv*, and Vw*, respectively. Here, the voltage commands Vu*, Vv*, and Vw*, which are high-frequency voltage commands, are fundamental AC voltage commands having a fundamental frequency that is sufficiently high so as not to rotate the rotating machine 2, a phase difference of 120° between the phases, and the same effective voltage value for each phase. The voltage command calculation unit 32 outputs the voltage commands Vu*, Vv*, and Vw* to the PWM signal generation unit 33 via the voltage command adjustment unit 39. The voltage command adjuster 39 outputs adjusted voltage commands Vu*, Vv*, Vw*, which are adjustment voltage commands sgca obtained by adjusting the voltage commands Vu*, Vv*, Vw* in a specific voltage unit interval Tru based on the adjustment target phase Dp and adjustment amount Ds output from the adjustment amount determiner 36, to the PWM signal generator 33. When generating the adjustment voltage command sgca, the voltage command adjuster 39 generates the adjustment voltage command sgca from the voltage command sgc based on the adjustment target phase Dp and adjustment amount Ds so as to include a current detection command 120 that detects the phase current of the detection target phase Pid. In other words, the current detection command 120 is set by generating the adjustment voltage command sgca. By using voltage commands Vu*, Vv*, and Vw*, which are high-frequency voltage commands, as commands to control the power conversion unit 3, it is possible to prevent the rotating machine 2 from rotating, and to bring the phase difference Δγ, which is the difference between the phase of the voltage applied to each phase of the rotating machine 2 and the phase of the phase current flowing through each phase of the rotating machine 2, closer to 90°. The phase current of the rotating machine 2 will be referred to as the rotating machine current as appropriate. Furthermore, the voltage command vector Vuvw* will be referred to simply as the voltage command Vuvw* as appropriate.

[0029] Furthermore, in the rotating machine drive mode Md1, the voltage command calculation unit 32 calculates a voltage command sgc for driving the rotating machine 2 at a desired speed based on the three-phase current Iuvw, which is the phase current of the three phases of the rotating machine 2 output by the phase current output unit 31 described above, and a speed command ωr* input from a higher-level control device or the like. The voltage command sgc in the rotating machine drive mode Md1 is a voltage command vector Vuvw0*. The U-phase, V-phase, and W-phase components of the voltage command vector Vuvw0* are voltage commands Vu0*, Vv0*, and Vw0*, respectively. In the rotating machine drive mode Md1, the voltage command adjustment unit 39 does not adjust the voltage command sgc. Where appropriate, the voltage command vector Vuvw0* will be simply referred to as a voltage command Vuvw0*.

[0030] The PWM signal generation unit 33 generates an on / off signal sg2 of a PWM signal corresponding to each of the switching elements 11a to 11f of the power conversion unit 3 based on the carrier signal 51 and the adjustment voltage command sgca, which includes the three-phase voltage command sgc and the current detection command 120 output by the voltage command calculation unit 32. More specifically, the PWM signal generation unit 33 generates the on / off signal sg2 of the PWM signal by comparing the voltage commands Vu*, Vv*, and Vw*, which are high-frequency voltage commands, with the carrier signal 51. Note that the adjustment voltage command sgca also includes the voltage command sgc that is not adjusted. Therefore, when the voltage command sgc is not adjusted, the command input to the PWM signal generation unit 33 is appropriately described as the voltage command sgc.

[0031] The on / off signal sg2 of the PWM signal corresponding to the U-phase switching element 11a is an on / off signal Up2. The on / off signal sg2 of the PWM signal corresponding to the U-phase switching element 11b is an on / off signal Un2. The on / off signal sg2 of the PWM signal corresponding to the V-phase switching element 11c is an on / off signal Vp2. The on / off signal sg2 of the PWM signal corresponding to the V-phase switching element 11d is an on / off signal Vn2. The on / off signal sg2 of the PWM signal corresponding to the W-phase switching element 11e is an on / off signal Wp2. The on / off signal sg2 of the PWM signal corresponding to the W-phase switching element 11f is an on / off signal Wn2.

[0032] When measuring the inductance Lm of the rotating machine 2, i.e., during the inductance measurement mode Md2, the PWM signal generator 33 generates an on-off signal sg2 by shifting the PWM signal based on the voltage command sgc, which is the unadjusted PWM signal, forward or backward in time or by expanding or contracting the pulse width so as to ensure a current detection time Tid for detecting a DC current (DC bus current Idc) reflecting the current of the detection target phase Pid during the period of the carrier signal 51 (the period of the carrier period Tc). When shifting the pulse of the PWM signal, i.e., when performing pulse shift, the average value of the high-frequency voltage command during the carrier period Tc is maintained constant before and after the pulse shift. To achieve this, for example, the high-frequency voltage command for the first-half carrier Trmf is increased by the command value adjustment amount α, and the high-frequency voltage command for the second-half carrier Trms is decreased by the command value adjustment amount α. The adjustment target phase Dp, which is the phase for which the pulse shift is performed, and the adjustment amount Ds corresponding to the command value adjustment amount α are determined by an adjustment amount determination unit 36, which will be described later. When the pulse width is to be expanded or contracted, the adjustment amount determination unit 36 ​​determines the adjustment target phase Dp, which is the phase for which the pulse width adjustment is performed, and the adjustment amount Ds corresponding to the command value adjustment amount α. The pulse width adjustment of the PWM signal can also be considered an adjustment by voltage command value compensation. The cycle period of the carrier signal 51 will be referred to as the carrier period, as appropriate.

[0033] The adjustment amount determiner 36 determines an adjustment target phase Dp and an adjustment amount Ds for shifting the pre-adjustment PWM signal or adjusting the pulse width, based on the detection target phase Pid and the current detection timing (detection timing Tg) when measuring the inductance Lm of the rotating machine 2. Information on the detection target phase Pid is included in the detection target phase signal sgp output by the timing determiner 35, and information on the detection timing Tg is included in the detection timing signal sgs output by the timing determiner 35.

[0034] The timing determiner 35 outputs a detection target phase signal sgp including information on the detection target phase Pid and a detection timing signal sgs including information on the detection timing Tg. When measuring the inductance Lm of the rotating machine 2, the timing determiner 35 determines the detection target phase Pid, ​​which is the phase of the current of the rotating machine 2 reflected in the DC current (DC bus current Idc) detected by the current detector 5, and the detection timing Tg for detecting the DC current (DC bus current Idc), i.e., the current detection timing, based on a predetermined phase difference Δγ between the rotating machine currents Imu, Imv, and Imw, which are currents of each phase flowing through the rotating machine 2, and the phase voltages Vu, Vv, and Vw, which are voltages of each phase supplied to the rotating machine 2, and the voltage command sgc. The phase difference Δγ is, for example, 90°. In the first embodiment, the phase difference Δγ is 90°. An example in which the phase difference Δγ is different from 90° will be described in the second embodiment.

[0035] The timing determination unit 35 utilizes the fact that the phase difference Δγ between the high-frequency voltage or high-frequency voltage command that generates a fundamental wave current in the rotating machine 2 and the rotating machine current is 90°, and determines that the peak of the current of a certain phase (target phase) will appear at a timing 90° delayed from the time (timing) at which the peak of the high-frequency voltage or high-frequency voltage command of that phase appears, and determines the detection timing Tg for detecting the current of the target phase so that the current value closest to the peak value of the phase current of the target phase can be detected.

[0036] FIG. 17 shows a case where the phase difference Δγ between a phase voltage waveform 46, which is a waveform of a high-frequency voltage, and a phase current waveform 47, which is a waveform of a rotating machine current Im, is 90°. The phase voltage waveforms 46 are waveforms of phase voltages Vu, Vv, and Vw, and the phase current waveforms 47 are waveforms of rotating machine currents Imu, Imv, and Imw. FIG. 17 shows a phase current waveform 47 of a fundamental wave, which is a sine wave or cosine wave, and a phase voltage waveform 46 of a fundamental wave, which is a cosine wave or sine wave, in which the phase difference Δγ between the phase current waveform 47 and the phase voltage waveform 46 is 90°. The symbol Im is used to refer to the rotating machine current, and Imu, Imv, and Imw are used to distinguish between them. The horizontal axes of the phase voltage waveforms 46 and the phase current waveforms 47 represent time. The vertical axis of the phase voltage waveform 46 represents voltage, and the vertical axis of the phase current waveform 47 represents current. The phase voltage waveform 46 is, for example, a sine wave.

[0037] The positive peak of the phase voltage waveform 46 appears at time tc1, and the negative peak appears at time tc2. In the first embodiment, the timing determination unit 35 determines that the phase difference Δγ between the voltage command sgc, which is a high-frequency voltage command, and the rotating machine current is 90° due to the application of the high-frequency voltage, and therefore determines that the positive peak of the phase current of the phase corresponding to the voltage command sgc (target phase) appears at time tc3, which is 90° delayed from time tc1. Similarly, the timing determination unit 35 determines that the negative peak of the phase current of the phase corresponding to the voltage command sgc (target phase) appears at time tc4, which is 90° delayed from time tc2. By setting the detection timing Tg near time tc3 and time tc4, the timing determination unit 35 can accurately detect the positive and negative peaks of the target phase current. It is desirable that the detection timing Tg be as close as possible to the timing of time tc3 and the timing of time tc4. In the present disclosure, by detecting current values ​​as close as possible to the positive peak and the negative peak of the current of the target phase, it is possible to detect the positive peak and the negative peak of the current of the target phase with high accuracy. Detecting the positive peak value and the negative peak value of the current of the target phase is difficult. However, in the present disclosure, since the vicinity of the positive peak value and the vicinity of the negative peak value of the current of the target phase are detected, the terms "detecting the positive peak" and "detecting the negative peak" are used appropriately, such as the phase in which the positive peak of the rotating machine current Im is detected and the phase in which the negative peak of the rotating machine current Im is detected.

[0038] The timing determination unit 35 determines the detection target phase Pid for detecting the positive peak of the rotating machine current Im and the detection target phase Pid for detecting the negative peak of the rotating machine current Im to be the phase in which the sign of the voltage command sgc or the three-phase voltage Vuvw applied to the rotating machine 2 is inverted at the timing (sign reversal timing Tsr (see FIG. 18)) of the end of the voltage unit interval Tru (see FIGS. 9 and 10), and determines the detection timing Tg to be the voltage unit interval before the sign reversal timing Tsr or the voltage unit interval Tru after the sign reversal timing Tsr, based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr.

[0039] The inductance measuring device 1 of the first embodiment will be described in detail. FIGS. 9 and 10 show a carrier signal 51. The carrier signal 51 is a triangular wave signal, and the amplitude between the dashed lines 49a and 49b is determined based on the DC bus voltage Vdc. In FIGS. 9 and 10, the horizontal axis represents time, and the vertical axis represents amplitude. The carrier signal 51 has a peak Pp, which is a positive peak, and a valley Pv, which is a negative peak. The carrier signal 51 has a carrier period Tc. The starting point of the carrier period Tc can be either the peak Pp or the valley Pv. FIG. 9 shows two periods of the carrier signal 51 starting at the peak Pp, while FIG. 10 shows two periods of the carrier signal 51 starting at the valley Pv. In FIG. 9, the starting points of the carrier period Tc are times tpp1, tpp2, and tpp3, which are the times of the peak Pp. The valleys Pv in FIG. 9 appear at times tpv1 and tpv2. In FIG. 10 , the starting points of the carrier period Tc are times tpv1, tpv2, and tpv3, which are the times of the troughs Pv. The starting point of the carrier period Tc is also the end point of the previous carrier period Tc. The peaks Pp in FIG. 10 appear at times tpp1 and tpp2. In one carrier period Tc, the period from the first peak at the start to the second peak on the opposite side is referred to as the first half of the carrier period Trms, and the period from the second peak to the first peak at the end is referred to as the second half of the carrier period Trms. The first half of the carrier period Trms and the second half of the carrier period Trms are equal in length, and their lengths correspond to half of the carrier period Tc. The value of the DC bus voltage Vdc may be detected by a separate voltage detector, or may be a preset fixed value if the DC bus voltage Vdc is constant.

[0040] Because the carrier signal 51 changes its tendency to change every half of the carrier period Tc, the carrier signal 51 can be described using half of the carrier period Tc as a voltage unit interval Tru. The peaks Pp and valleys Pv are the vertices (first vertices) where the carrier signal 51 has a maximum value and the valleys Pv are the vertices (second vertices) where the carrier signal 51 has a minimum value, respectively. The peaks Pp and valleys Pv are referred to as the first vertex and the second vertex, respectively, as appropriate. The voltage unit interval Tru is the interval between two adjacent vertices, i.e., the interval in which the first vertex and the second vertex are consecutive. The voltage unit interval Tru in which the carrier signal 51 exhibits a tendency to decrease in value over time from the first vertex to the second vertex is referred to as the first voltage unit interval Tru1, and the voltage unit interval Tru in which the carrier signal 51 exhibits a tendency to increase in value over time from the second vertex to the first vertex is referred to as the second voltage unit interval Tru2. The voltage unit intervals are generally referred to as Tru, and are distinguished by Tru1 and Tru2. 9, the section of one cycle of carrier signal 51 whose starting point is peak Pp has a first voltage unit interval Tru1 and a second voltage unit interval Tru2 that is continuous with the first voltage unit interval Tru1. The section of one cycle of carrier signal 51 whose starting point is valley Pv that is shown in FIG. 10 has a second voltage unit interval Tru2 and a first voltage unit interval Tru1 that is continuous with the second voltage unit interval Tru2.

[0041] FIG. 11 shows the carrier signal 51, the voltage command vector Vuvw*, and the on / off signal sg2. When the voltage command adjustment unit 39 outputs an adjusted voltage command sgca without adjusting the voltage command sgc, the PWM signal generation unit 33 outputs the adjusted voltage command sgca as an on / off signal sg2 of a PWM signal based on the voltage command sgc. A method for generating the on / off signal sg2 of a PWM signal will be described with reference to FIG. 11. FIG. 11 shows an example in which the start point of the carrier period Tc is a peak Pp at time tpp1, and the end point of the carrier period Tc is a peak Pp at time tpp2. The carrier signal 51 reaches a valley Pv at time tpv1. In FIG. 11, the horizontal axis represents time, the vertical axes of the carrier signal 51 and the voltage command vector Vuvw* represent voltage, and the vertical axis of the on / off signal sg2 represents a digital signal level. Voltage commands Vu*, Vv*, and Vw* for the U, V, and W phases are command waveforms 61u, 61v, and 61w, respectively. On-off signals Up2, Vp2, and Wp2 for the upper arms of the U, V, and W phases are on-off signal waveforms 60a, 60c, and 60e. On-off signals Un2, Vn2, and Wn2 for the lower arms of the U, V, and W phases are on-off signal waveforms 60b, 60d, and 60f. The on levels of the on-off signals Up2, Un2, Vp2, Vn2, Vp2, and Wn2 are signal levels when the corresponding switching elements 11a, 11b, 11c, 11d, 11e, and 11f are turned on. The off level of each on / off signal Up2, Un2, Vp2, Vn2, Vp2, and Wn2 is the signal level when the corresponding switching element 11a, 11b, 11c, 11d, 11e, or 11f is turned off. In each diagram showing the on / off signal sg2 and the carrier signal 51, the on level and the off level are indicated as "on" and "off," respectively. Furthermore, in each diagram showing the on / off signal sg2 and the carrier signal 51, the first voltage unit section Tru1 and the second voltage unit section Tru2 are also indicated, along with the first half of the carrier Trmf and the second half of the carrier Trms.

[0042] The PWM signal generator 33 compares the carrier signal 51 with voltage commands Vu*, Vv*, and Vw*, which are high-frequency voltage commands in the adjusted voltage command sgca output from the voltage command adjuster 39 for the U, V, and W phases. If the carrier signal 51 is greater than the high-frequency voltage command value, the PWM signal generator 33 sets the upper arm on / off signals Up2, Vp2, and Wp2 of each phase to an off level and the lower arm on / off signals Un2, Vn2, and Wn2 to an on level. If the carrier signal 51 is equal to or less than the high-frequency voltage command value, the PWM signal generator 33 sets the upper arm on / off signals Up2, Vp2, and Wp2 of each phase to an on level and the lower arm on / off signals Un2, Vn2, and Wn2 to an off level. Therefore, as shown in FIG. 11 , the on / off signal sg2 of the PWM signal has a symmetrical pattern between the first half of the carrier Trmf and the second half of the carrier Trms.

[0043] Since the carrier signal 51 is equal to or less than the command value of the voltage command Vu* of the voltage command vector Vuvw* from time t1 to time t6, the on-off signal Up2 is at the on level and the on-off signal Un2 is at the off level during this period. Since the carrier signal 51 is equal to or less than the command value of the voltage command Vv* of the voltage command vector Vuvw* from time t2 to time t5, the on-off signal Vp2 is at the on level and the on-off signal Vn2 is at the off level during this period. Since the carrier signal 51 is equal to or less than the command value of the voltage command Vw* of the voltage command vector Vuvw* from time t3 to time t4, the on-off signal Wp2 is at the on level and the on-off signal Wn2 is at the off level during this period.

[0044] 12 shows the relationship between the set of levels of the upper arm on / off signals Up2, Vp2, and Wp2 for the U-, V-, and W-phases and the state of the DC bus current Idc. The state of the DC bus current Idc is represented by a current value of 0 or the phase and sign to which it is reflected. When the on / off signals Up2, Vp2, and Wp2 are all on or all off, the current value of the DC bus current Idc is 0. The sign of the DC bus current Idc is negative (-) when it flows from the negative DC terminal 13n to the negative power supply terminal 17n, and positive (+) when it flows from the negative power supply terminal 17n to the negative DC terminal 13n. The direction of the rotating machine current of the U-, V-, and W-phases of the rotating machine 2 is positive (+) when it flows from the power conversion unit 3 to the rotating machine 2. When the on-off signals Up2, Vp2, and Wp2 are at the on level, on level, and off level, the DC bus current Idc reflects the W-phase rotating machine current Imw and has a positive sign. When the on-off signals Up2, Vp2, and Wp2 are at the on level, off level, and on level, the DC bus current Idc reflects the V-phase rotating machine current Imv and has a positive sign. When the on-off signals Up2, Vp2, and Wp2 are at the on level, off level, and off level, the DC bus current Idc reflects the U-phase rotating machine current Imu and has a negative sign.

[0045] When the on-off signals Up2, Vp2, and Wp2 are at the off level, on level, and on level, the DC bus current Idc reflects the U-phase rotating machine current Imu and has a positive sign. When the on-off signals Up2, Vp2, and Wp2 are at the off level, on level, and off level, the DC bus current Idc reflects the V-phase rotating machine current Imv and has a negative sign. When the on-off signals Up2, Vp2, and Wp2 are at the off level, off level, and on level, the DC bus current Idc reflects the W-phase rotating machine current Imw and has a negative sign. A set of on-off signals Up2, Vp2, Wp2, Un2, Vn2, and Wn2, which are elements of the on-off signal sg2 for which the current value of the DC bus current Idc is zero, is a zero-voltage vector 122. A set of on-off signals Up2, Vp2, Wp2, Un2, Vn2, and Wn2, which are elements of on-off signal sg2 whose current value of DC bus current Idc is not zero, is a non-zero voltage vector 123. A set of elements of on-off signal sg2 is an on-off signal vector 118, and the on-off signal vector 118 has a zero voltage vector 122 and a non-zero voltage vector 123.

[0046] 11 also shows a zero voltage vector 122 and a non-zero voltage vector 123. The zero voltage vector 122 is a set of elements of the on / off signal sg2 from time tpp1 to time t1, from time t3 to time t4, and from time t6 to time tpp2. The non-zero voltage vector 123 is a set of elements of the on / off signal sg2 from time t1 to time t3, and from time t4 to time t6.

[0047] The processing of the voltage command adjuster 39 and the PWM signal generator 33 will now be described. As described above, the on / off signal sg2 of the PWM signal output from the PWM signal generator 33 in response to the adjusted voltage command sgca output from the voltage command adjuster 39 is a signal that has been adjusted by pulse shifting, voltage command value compensation, or the like during a specific period, i.e., the period during which the adjustment processing is performed. First, the adjustment processing by pulse shifting, i.e., pulse shift processing, will be described. During the period during which the adjustment processing is performed, a command identical to the pre-adjustment voltage command sgc is not input to the PWM signal generator 33, so the pre-adjustment on / off signal sg2 is not generated. Here, for comparison between before and after adjustment, the on / off signal without adjustment is referred to as the pre-adjustment on / off signal. FIG. 13 shows the carrier signal 51, voltage command vector Vuvw*, and on / off signals Up2, Vp2, and Wp2 before adjustment, and FIG. 16 shows the carrier signal 51, voltage command vector Vuvw*, and on / off signals Up2, Vp2, and Wp2 after pulse shift processing. 13 and 16 show a crest-start type example in which the start and end points of the carrier period Tc are crests Pp. Hereinafter, signal diagrams such as those in FIGS. 13 and 16 will be referred to as crest-start type signal explanatory diagrams, where appropriate. Furthermore, where appropriate, the waveform displays of the carrier signal 51 and the voltage command vector Vuvw* will be referred to as input waveform displays, and the waveform displays of the on / off signals of the PWM signals will be referred to as output waveform displays. In FIGS. 13 and 16, the carrier signal 51 has a crest Pp at time tpp1, a trough Pv at time tpv1, and a crest Pp at time tpp2. In FIGS. 13 and 16, the horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level.

[0048] Voltage commands Vu*, Vv*, and Vw*, which are high-frequency voltage commands for the U, V, and W phases, have command waveforms 63u, 63v, and 63w, respectively. This is the case where the command values ​​of the U-phase voltage command Vu* and the V-phase voltage command Vv* are equal, and the W-phase voltage command Vw* has a smaller command value than the high-frequency voltage commands for the remaining two phases. On-off signals Up2, Vp2, and Wp2 before adjustment in the upper arms of the U, V, and W phases have on-off signal waveforms 64u, 64v, and 64w, respectively. Figure 13 shows that the timing determination unit 35 plans to detect the U-phase rotating machine current Imu at detection timing Tu and plans to detect the V-phase rotating machine current Imv at detection timing Tv. Because the carrier signal 51 is equal to or less than the command values ​​of the voltage commands Vu* and Vv* from time t1 to time t4, the pre-adjustment on-off signals Up2 and Vp2 are at an on level during this period. Because the carrier signal 51 is equal to or less than the command value of the voltage command Vw* from time t2 to time t3, the pre-adjustment on-off signal Wp2 is at an on level during this period. FIG. 13 illustrates a case where the command values ​​of the U-phase voltage command Vu* and the V-phase voltage command Vv* are equal, the W-phase voltage command Vw* is smaller than the command values ​​of the voltage commands Vu* and Vv* for the remaining two phases, and the difference ΔW between the rising edge of the pulse of the pre-adjustment on-off signal Up2 for the U-phase upper arm and the rising edge of the pulse of the pre-adjustment on-off signal Vp2 for the V-phase upper arm within the range of interest 52 indicated by the dashed rectangle is smaller than the current detection time Tid, which is the time required for current detection. Even when the command values ​​of the voltage commands are the same, the difference ΔW may occur due to the characteristics of each switching element. The on-off signals Up2 and Vp2 before adjustment in the range of interest 52 correspond to the on-off signal waveforms 48a and 48b in Fig. 14, respectively. That is, in the diagram before adjustment in Fig. 13, the U-phase rotating machine current Imu cannot be detected at the detection timing Tu, and adjustment is required to enable detection at the detection timing Tu. In the case of the detection timing Tv in Fig. 13, the difference ΔW is the difference between the falling pulse edge of the on-off signal Up2 before adjustment and the falling pulse edge of the on-off signal Vp2 before adjustment.In the state of Figure 13, similar to the current detection at detection timing Tu, the current detection at detection timing Tv is such that the pre-adjustment on / off signals Up2, Vp2, and Wp2 are zero voltage vector 122 (see Figure 11), and therefore the V-phase rotating machine current Imv cannot be detected.

[0049] FIG. 14 shows the case where ΔW<Tid, which corresponds to an enlarged view of the area of ​​interest 52, and FIG. 15 shows the case where ΔW>Tid. In FIGS. 14 and 15, the horizontal axis represents time, and the vertical axis represents the output waveform, which represents the digital signal level. The on-off signal waveform 48a of one phase changes from the off level to the on level at time tp1. The on-off signal waveform 48b of the other phase changes from the off level to the on level at time tp2. The pulse rise difference ΔW is the difference between the on-off signal waveform 48a and the on-off signal waveform 48b, which is expressed in time as time tp2 - time tp1. In FIGS. 14 and 15, an example is shown in which the start time of the current detection time Tid is time tp1 and the end time of the current detection time Tid is the detection timing Tg. For example, the current detection time Tid is the execution time of AD conversion, and the detection timing Tg shown in FIGS. 14 and 15 corresponds to the time when the AD-converted detection value is determined. In the case of Fig. 14, the on / off signal waveform 48b changes from the off level to the on level in a time shorter than the current detection time Tid from time tp1. In the case of ΔW>Tid in Fig. 15, the on / off signal waveform 48b changes from the off level to the on level at a time (time tp2 in Fig. 15) after the end of the current detection time Tid from time tp1. In the case of ΔW<Tid in Fig. 14, current detection is not possible, but in the case of ΔW>Tid in Fig. 15, current detection is possible.

[0050] 16 , in order to detect the U-phase rotating machine current Imu at the detection timing Tu and the V-phase rotating machine current Imv at the detection timing Tv, the unadjusted on / off signal Up2 of the U-phase upper arm is shifted forward in time within the carrier cycle Tc as indicated by arrow 54u to generate an adjusted on / off signal Up2, and the unadjusted on / off signal Vp2 of the V-phase upper arm is shifted backward in time within the carrier cycle Tc as indicated by arrow 54v to generate an adjusted on / off signal Vp2. In this case, in order to detect the U-phase rotating machine current Imu at the detection timing Tu, the adjustment amount determiner 36 determines the adjustment amount Dsu corresponding to the U-phase command value adjustment amount α1 so that the time from when the adjusted on / off signal Up2 of the U-phase upper arm changes to the on level to the detection timing Tu is equal to or longer than the current detection time Tid. Furthermore, in order to detect the V-phase rotating machine current Imv at the detection timing Tv, the adjustment amount determiner 36 determines an adjustment amount Dsv corresponding to the V-phase command value adjustment amount α2 so that the time from when the adjusted on-off signal Up2 of the U-phase upper arm transitions to the off level to the detection timing Tv is equal to or longer than the current detection time Tid. The detectable period 53a is the period from the pulse end of the on-off signal Up2 in the first half of the carrier Trmf to the detection timing Tu, and this period is equal to or longer than the current detection time Tid. The detectable period 53b is the period from the pulse end of the on-off signal Up2 in the second half of the carrier Trms to the detection timing Tv, and this period is equal to or longer than the current detection time Tid. The adjustment amounts are generally designated by the symbol Ds, and when distinguished, Dsu, Dsv, and Dsw are used.

[0051] This will be explained more specifically. As shown in FIG. 4 , carrier signal 51 and voltage command vector Vuvw*, which is voltage command sgc, are input to voltage command adjustment unit 39. FIG. 16 shows an example in which the detection target phase Pid in the first half of carrier Trmf is U-phase, the detection timing Tg of the detection target phase Pid is detection timing Tu, and the detection target phase Pid in the second half of carrier Trms is V-phase, and the detection timing Tg of the detection target phase Pid is detection timing Tv. Voltage command adjustment unit 39 receives adjustment target phase Dp and adjustment amount Ds, and changes voltage command Vu* when adjustment target phase Dp is U-phase from command waveform 63u in FIG. 13 to command waveform 65u based on adjustment amount Dsu corresponding to command value adjustment amount α1, and changes voltage command Vv* when adjustment target phase Dp is V-phase from command waveform 63v in FIG. 13 to command waveform 65v based on adjustment amount Dsv corresponding to command value adjustment amount α2. Compared to the command waveform 63u, the command value of the command waveform 65u increases by the command value adjustment amount α1 at the first half of the carrier Trmf and decreases by the command value adjustment amount α1 at the second half of the carrier Trms. Compared to the command waveform 63v, the command value of the command waveform 65v decreases by the command value adjustment amount α2 at the first half of the carrier Trms and increases by the command value adjustment amount α2 at the second half of the carrier Trms. The command waveform 65w of the W-phase voltage command Vw* is the same as the command waveform 63w in FIG.

[0052] The U-phase on / off signal Up2 has an on / off signal waveform 66u, the V-phase on / off signal Vp2 has an on / off signal waveform 66v, and the W-phase on / off signal Wp2 has an on / off signal waveform 66w. The U-phase on / off signal Up2 is at an on level from time ta1 to time tb1, and the V-phase on / off signal Vp2 is at an on level from time ta2 to time tb2. The W-phase on / off signal Wp2 is at an on level from time t2 to time t3. During the period from time ta1 to time ta2, the on / off signals Up2, Vp2, and Wp2 are "on," "off," and "off," so the U-phase rotating machine current Imu can be detected from FIG. 12. The timing determination unit 35 determines the phase in which current can be detected, generates a detection target phase signal sgp indicating that the detection target phase Pid is the U phase, and a detection timing signal sgs indicating the time of the detection timing Tg of the U phase, and outputs these to the adjustment amount determination unit 36.

[0053] During the period from time tb1 to time tb2, the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "off," so the V-phase rotating machine current Imv can be detected as shown in Fig. 12. The timing determination unit 35 determines the phases for which current can be detected, and generates a detection target phase signal sgp indicating that the detection target phase Pid indicates the V-phase, and a detection timing signal sgs indicating the time of the detection timing Tg for the V-phase, and outputs these to the adjustment amount determination unit 36.

[0054] As described above, the adjustment amount determination unit 36 ​​determines the phase to be adjusted Dp and the adjustment amount Ds based on the information on the detection target phase signal sgp and the detection timing signal sgs output from the timing determination unit 35, and the PWM signal generation unit 33 generates the adjusted on / off signal sg2 by shifting the pre-adjustment on / off signal sg2 forward or backward in time within the carrier period Tc based on the adjustment voltage command sgca output from the voltage command adjustment unit 39, thereby making it possible to detect the current of a specified phase at a specified timing without changing the average voltage during one carrier period Tc.

[0055] An example of the operation of the inductance measuring device 1 of embodiment 1 will be described below. Fig. 18 shows a first example of a carrier signal 51 whose start point in the period of the carrier cycle Tc is a peak Pp, voltage commands Vu*, Vv*, Vw*, and a rotating machine current Im which is a three-phase current of the rotating machine 2, and Fig. 21 shows a second example of a carrier signal 51 whose start point in the period of the carrier cycle Tc is a valley Pv, voltage commands Vu*, Vv*, Vw*, and a rotating machine current Im which is a three-phase current of the rotating machine 2. 26 shows a third example of the carrier signal 51, the voltage commands Vu*, Vv*, and Vw*, and the rotating machine current Im, which is the three-phase current of the rotating machine 2, in which the starting point of the carrier period Tc is a peak Pp, and FIG. 28 shows a fourth example of the carrier signal 51, the voltage commands Vu*, Vv*, and Vw*, and the rotating machine current Im, which is the three-phase current of the rotating machine 2, in which the starting point of the carrier period Tc is a valley Pv. FIGS. 18 and 26 are diagrams of the crest-start type, and FIGS. 21 and 28 are diagrams of the valley-start type, in which the starting and ending points of the carrier period Tc are valleys Pv. A first example of the operation of the inductance measurement device 1 will be described using FIGS. 18 to 20 and 24, and a second example of the operation of the inductance measurement device 1 will be described using FIGS. 21 to 23 and 25. 26 and 27 will be used to explain a third example of the operation of the inductance measuring device 1, and Fig. 28 and 29 will be used to explain a fourth example of the operation of the inductance measuring device 1. Fig. 18, Fig. 21, Fig. 26, and Fig. 28 show examples in which the phase difference Δγ between the high-frequency voltage command and the rotating machine current Im is 90°.

[0056] First, a first example of the operation of the inductance measurement device 1 will be described. The operations of the timing determination unit 35, voltage command adjustment unit 39, PWM signal generation unit 33, adjustment amount determination unit 36, and phase current output unit 31 in the first embodiment will be described in more detail. In FIG. 18 , the voltage command calculation unit 32 outputs the components of the voltage command vector Vuvw*, which is a high-frequency voltage command expressed as a vector, i.e., the voltage commands Vu*, Vv*, and Vw*, as rectangular wave voltages with a 120° phase difference between the phases and equal voltage amplitudes for each phase. Furthermore, the command period Tmc, which is the period of the voltage commands Vu*, Vv*, and Vw*, is 12 times the carrier period Tc. The waveforms of the voltage commands Vu*, Vv*, and Vw* are command waveforms 67u, 67v, and 67w, respectively. In the first example shown in FIG. 18 , the voltage commands Vu*, Vv*, and Vw* are rectangular wave voltages. By using a rectangular wave voltage, it is possible to easily determine the timing corresponding to the voltage peak position when the voltage commands Vu*, Vv*, and Vw* are fundamental waves like the phase voltage waveform 46. Furthermore, it is possible to easily calculate the effective voltage value when the voltage commands Vu*, Vv*, and Vw* are fundamental waves like the phase voltage waveform 46. Here, the command value is changed at a frequency high enough to prevent the rotating machine 2 from rotating. Therefore, the rotating machine current Im reaches its peak value at the pulse edge where the polarity of the rectangular wave voltage changes (the voltage sign changes between a positive voltage value and a negative voltage value). When the on-off signal sg2 is generated using the voltage command vector Vuvw* having the command waveform shown in FIG. 18 , the on-off signal sg2 becomes a rectangular wave voltage similar to the voltage command vector Vuvw*. Since the rotating machine current Im has a waveform similar to the phase current waveform 47 in FIG. 17 , the voltage command having command waveforms 67u, 67v, and 67w is used as the basic voltage command. Therefore, the voltages of the three phases supplied to the rotating machine 2 by the command waveforms 67u, 67v, and 67w can be said to be quasi-fundamental waves.

[0057] The pulse edges at which the polarities of the voltage commands Vu*, Vv*, and Vw* of the rectangular wave voltage change are the sign reversal timings Tsr at which the sign of the voltage command sgc mentioned above reverses at the ends of the voltage unit interval Tru. In Fig. 18, the sign reversal timings Tsr are assigned to the time tc3 at which the sign of the voltage command Vu* reverses from positive to negative and the time tc4 at which the sign of the voltage command Vu* reverses from negative to positive. The time tc0 at which the sign of the voltage command Vu* reverses from negative to positive is also the sign reversal timing Tsr. The voltage commands Vv* and Vw* also have the sign reversal timings Tsr at which the sign reverses from positive to negative and the sign reversal timings Tsr at which the sign reverses from negative to positive. As with the voltage commands Vu*, Vv*, Vw* for the square wave voltage, the voltage commands Vu*, Vv*, Vw* for the fundamental wave voltage also have sign reversal timings Tsr where the sign is reversal from positive to negative and sign reversal timings Tsr where the sign is reversal from negative to positive. Because the quasi-fundamental AC voltage output from the power conversion unit 3 follows the quasi-fundamental voltage command sgc, the quasi-fundamental three-phase voltage Vuvw also has sign reversal timings Tsr where the sign is reversal from positive to negative and sign reversal timings Tsr where the sign is reversal from negative to positive.

[0058] As described above, the voltage commands Vu*, Vv*, and Vw* having command waveforms 67u, 67v, and 67w are three-phase voltage commands sgc, i.e., fundamental voltage commands 119, in which the three-phase voltages supplied to the rotating machine 2 are quasi-fundamental waves. The fundamental voltage command 119 generates a fundamental current in the rotating machine 2. A phase in which the sign of the command value of the fundamental voltage command 119 is inverted is designated as a special phase 124. A special phase 124 in which the sign of the command value of the fundamental voltage command 119 changes from positive to negative is designated as a first special phase 125. A special phase 124 in which the sign of the command value of the fundamental voltage command 119 changes from negative to positive is designated as a second special phase 126. The rotating machine current period Tmi, like the command period Tmc, is 12 times the carrier period Tc. Time tc3 is designated as a command period midpoint Tmcc, which is the midpoint of the command period Tmc for the U phase. In the first special phase 125, the sign of the command value of the basic voltage command 119 changes from positive to negative, so time tc3 in Fig. 18 corresponds to time tc3 in Fig. 17. In the second special phase 126, the sign of the command value of the basic voltage command 119 changes from negative to positive, so time tc4 in Fig. 18 corresponds to time tc4 in Fig. 17.

[0059] The U-phase rotating machine current Im, or the rotating machine current Imu, reaches a negative peak at time tc0, a positive peak at time tc3, and a negative peak at time tc4. That is, the rotating machine current Im of the first special phase 125 reaches a positive peak at the sign reversal timing Tsr, and the rotating machine current Im of the second special phase 126 reaches a negative peak at the sign reversal timing Tsr. The first special phase 125 and the second special phase 126 are the phases in which the positive peak and the negative peak of the rotating machine current Im are detected, respectively. The rotating machine current Im reaches a positive or negative peak at the sign reversal timing Tsr, and the detection timing Tg for detecting the rotating machine current Im of the first special phase 125 and the second special phase 126 is determined to be one of two adjacent voltage unit intervals Tru that include the sign reversal timing Tsr.

[0060] Time tc1 in Fig. 18 is the intermediate time of the positive command value period of the voltage command Vu*, and the rotating machine current Imu is approximately 0, so it corresponds to time tc1 in Fig. 17 . Time tc2 in Fig. 18 is the intermediate time of the negative command value period of the voltage command Vu*, and the rotating machine current Imu is approximately 0, so it corresponds to time tc2 in Fig. 17 . The period from time tc1 to time tc3 in Fig. 18 is the command phase difference Δθ in one phase of the voltage command sgc, and the command phase difference Δθ is 90°. The period from time tc2 to time tc4 in Fig. 18 is the command phase difference Δθ in one phase of the voltage command sgc, and the command phase difference Δθ is 90°. The period from the time indicated by dashed line 55a to time tc3 is the U-phase current detection period Sdu, and the period from time tc4 to the time indicated by dashed line 55b is the U-phase current detection period Sdu. The period of the carrier cycle Tc ending at time tc3 when the command value of the voltage command sgc in the peak-start type changes from positive to negative is defined as a first current detection period Sd1, and the period of the carrier cycle Tc starting at time tc4 when the command value of the voltage command sgc in the peak-start type changes from negative to positive is defined as a second current detection period Sd2. The U-phase current detection period Sdu from the time indicated by dashed line 55a to time tc3 is the first current detection period Sd1, and the U-phase current detection period Sdu from time tc4 to the time indicated by dashed line 55b is the second current detection period Sd2. In Figure 18, the U-phase is denoted by the symbols Sdu, Sd1, and Sd2, but the same applies to the V-phase and W-phase.

[0061] The time tc1 of the positive peak when the phase voltage Vu is a fundamental wave as in Fig. 17 corresponds to the time tc1 which is the middle of the high level period of the command waveform 67u when the voltage command Vu* is a square wave as in Fig. 18. The time tc2 of the negative peak when the phase voltage Vu is a fundamental wave as in Fig. 17 corresponds to the time tc2 which is the middle of the low level period of the command waveform 67u when the voltage command Vu* is a square wave as in Fig. 18. The timing determination unit 35 determines that the positive peak of the U-phase rotating machine current Imu will appear at time tc3 which is 90° delayed from time tc1, and that the negative peak of the U-phase rotating machine current Imu will appear at time tc4 which is 90° delayed from time tc2. In order to detect the current closest to the positive and negative peaks of the U-phase rotating machine current Imu that appear at times tc3 and tc4, the timing determination unit 35 determines one of the phases for detecting current in the carrier period immediately before time tc3, i.e., the first current detection period Sd1, as the U-phase, and determines one of the phases for detecting current in the carrier period immediately after time tc4, i.e., the second current detection period Sd2, as the U-phase.

[0062] The timing determination unit 35 compares the case where the U-phase rotating machine current Imu is detected in the carrier period immediately before the time tc3, i.e., the first current detection period Sd1, with the case where the U-phase rotating machine current Imu is detected in the carrier period immediately after the time tc3 (see FIG. 20 ), and determines in which case a current closer to the positive peak of the U-phase rotating machine current Imu can be detected. In the example of FIG. 18 , the timing determination unit 35 determines that the U-phase is one of the phases in which current is detected in the carrier period immediately before the time tc3 (first current detection period Sd1). Therefore, the first current detection period Sd1 is a carrier period including the voltage unit section Tru before the sign reversal timing Tsr at which the positive peak of the rotating machine current Imu appears when the detection target phase Pid is the U phase.

[0063] Similarly, the timing determination unit 35 compares the case where the U-phase rotating machine current Imu is detected in the carrier period immediately before time tc4 with the case where the U-phase rotating machine current Imu is detected in the carrier period immediately after time tc4, i.e., the second current detection period Sd2, to determine in which case a current closer to the negative peak of the U-phase rotating machine current Imu can be detected. In the example of Fig. 18, the timing determination unit 35 determines that the U-phase is one of the phases in which current is detected in the carrier period immediately after time tc4 (the second current detection period Sd2), because the U-phase can be detected closer to the negative peak of the U-phase rotating machine current Imu than the case where the U-phase rotating machine current Imu is detected in the carrier period immediately after time tc4 (the second current detection period Sd2). Therefore, the second current detection period Sd2 is a carrier period including the voltage unit section Tru after the sign reversal timing Tsr at which the negative peak of the rotating machine current Imu appears when the detection target phase Pid is the U phase.

[0064] When determining whether a current closer to the positive peak of the U-phase rotating machine current Imu can be detected between detecting the U-phase rotating machine current Imu in the carrier period (first current detection period Sd1) immediately before the timing of time tc3 and detecting the U-phase rotating machine current Imu in the carrier period immediately after the timing of time tc3, or when determining whether a current closer to the negative peak of the U-phase rotating machine current Imu can be detected between detecting the U-phase rotating machine current Imu in the carrier period immediately before the timing of time tc4 and detecting the U-phase rotating machine current Imu in the carrier period (second current detection period Sd2) immediately after the timing of time tc4, the timing decision unit 35 will not consider detecting the current at this timing if it is determined that current detection is impossible based on the magnitude relationship between the command values ​​of the voltage commands Vu*, Vv*, Vw* and the current detection time Tid.

[0065] 19 and 20 are diagrams illustrating why, in the example of FIG. 18 , the U-phase is selected as one of the phases for detecting current during the carrier period (first current detection period Sd1) immediately before time tc3, which is the U-phase sign reversal timing Tsr. FIGS. 19 and 20 are explanatory diagrams of a peak-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 19 shows an example of the detection timing of the U-phase rotating machine current Imu when the U-phase rotating machine current Imu is detected during the carrier period (first current detection period Sd1) immediately before time tc3. The U-phase voltage command Vu* is represented by a command waveform 68u1 before shifting and a command waveform 68u2 after shifting. The V-phase voltage command Vv* without shifting is represented by a command waveform 68v, and the W-phase voltage command Vw* without shifting is represented by a command waveform 68w. The U-phase on / off signal Up2 after the shift is an on / on signal waveform 69u, the V-phase on / off signal Vp2 without shift processing is an on / on signal waveform 69v, and the W-phase on / off signal Wp2 without shift processing is an on / on signal waveform 69w.

[0066] In the command waveform 68u2, the command value at the first half of the carrier Trmf is decreased by the command value adjustment amount α compared to before the shift, and the command value at the second half of the carrier Trms is increased by the command value adjustment amount α compared to before the shift. After the shift, the U-phase on / off signal Up2 is at the on level from time t2 to time t6. The V-phase on / off signal Vp2 is at the on level from time t1 to time t5, and the W-phase on / off signal Wp2 is at the on level from time t3 to time t4. The period from time t3 to time t4 is the zero voltage vector period Z1 during which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t6 to time tc3 is a zero voltage vector period Z2 in which the on-off signals Up2, Vp2, and Wp2 are "off", "off", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t5 to time t6 is a non-zero voltage vector period in which the on-off signals Up2, Vp2, and Wp2 are "on", "off", and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detected voltage vector period Q1 in which the detected on-off signal vector 121 is output.

[0067] During the current detection voltage vector period Q1, a current detection command 120 is output in which the voltage command vector Vuvw* detects the rotating machine current Im. The time of the current detection voltage vector period Q1 is an adjustment amount Dsu, which corresponds to the current detection time Tid. This adjustment amount Dsu is realized by the command value adjustment amount α. In other words, the adjustment amount Dsu and the command value adjustment amount α are related to each other. The current detection command 120 is a three-phase voltage command sgc that equals the absolute value of the DC bus current Idc detected by the current detection unit 5 and the absolute value of the current (rotating machine current Im), which is the current of the phase with the largest absolute value among the three-phase currents of the rotating machine 2 and is closest to the positive or negative peak. Furthermore, the current detection command 120 may be a three-phase voltage command sgc adjacent to the middle of the command period (command period middle Tmcc) at which the command values ​​of the three-phase voltage commands sgc change in a constant command period Tmc and the sign of the command value for one phase is inverted, and may be a three-phase voltage command sgc such that the absolute value of the current (current at time tc3 or tc4 in FIG. 17 ) flowing through the phase (phase corresponding to time tc3 or tc4 in FIG. 17 ) having the smallest absolute value of the instantaneous value of the voltage supplied to the rotating machine 2 is equal to the absolute value of the DC bus current Idc detected by the current detection unit 5. The current of the phase with the largest absolute value among the three-phase currents of the rotating machine 2 and closest to the positive or negative peak (rotating machine current Im) is the current corresponding to time tc3 in FIG. 17 or the current corresponding to time tc4 in FIG.

[0068] Times tc3 and tc4 in Fig. 18 are timings at which the sign of the voltage command sgc that causes the PWM signal generator 33 to generate a rectangular wave voltage is inverted and which also represent the end of a voltage unit interval Tru, i.e., sign inversion timing Tsr. Times tc3 and tc4 in Fig. 17 are timings at which the sign of an AC voltage such as the three-phase voltage Vuvw applied to the rotating machine 2 is inverted and also represent the end of a voltage unit interval Tru, i.e., sign inversion timing Tsr. At times tc3 and tc4 in Fig. 18, the sign of the voltage command Vu* that is the U-phase voltage command sgc is inverted, and therefore the U-phase becomes the detection target phase Pid in the three phase currents Iu, Iv, and Iw to be detected. At times tc3 and tc4 in FIG. 17, when the sign of the U-phase voltage Vu in an AC voltage such as a three-phase voltage Vuvw is inverted, the U-phase becomes the detection target phase Pid in the three phase currents Iu, Iv, and Iw detected.

[0069] The case where the U-phase rotating machine current Imu is detected during the carrier period (first current detection period Sd1) immediately before time tc3 is, for example, detection timing Tu1 in FIG. 19 . Detection timing Tu1 allows the U-phase rotating machine current Imu to be detected immediately before the on-off signal Up2 of the U-phase upper arm transitions from an on level to an off level. It is not a problem if detection timing Tg, such as detection timing Tu1, coincides with a change in the on-off signal sg2 to be detected, since current detection is completed at detection timing Tg. The same applies to other figures. In FIG. 19 , the unadjusted on-off signal Up2 of the U-phase upper arm is shifted as indicated by arrow 54u to generate the adjusted on-off signal Up2 so that the U-phase rotating machine current Imu can be detected. The detected on-off signal vector 121 shown in FIG. 19 is a non-zero voltage vector 123 in which the on-off signals Up2, Vp2, and Wp2 are “on,” “off,” and “off,” allowing the U-phase rotating machine current Imu to be detected. The current detection command 120 shown in FIG. 19 is a command having command values ​​for each phase in the command waveforms 68u2, 68v, and 68w from time t5 to time t6. If the U-phase on / off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 19 will be only the W-phase current for which the non-zero voltage vector 123, i.e., the on / off signals Up2, Vp2, and Wp2, are "on," "on," and "off" from time t2 to time t3 or from time t4 to time t5. Therefore, in order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in FIG. 19, the V-phase on / off signal Vp2 may also be shifted from before adjustment.

[0070] On the other hand, when detecting the U-phase rotating machine current Imu in the carrier period immediately after time tc3, for example, this is detection timing Tu2 shown in FIG. 20 . Detection timing Tu2 is time t3, which is the current detection time Tid, after the adjustment amount Dsu has elapsed since the on-off signal Wp2 of the W-phase upper arm transitioned from the off level to the on level. In FIG. 20 , the pre-adjustment on-off signal Up2 of the U-phase upper arm is shifted as indicated by arrow 54u to generate the adjusted on-off signal Up2 so that the U-phase rotating machine current Imu can be detected. If the U-phase on-off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 20 is only the V-phase current for which the non-zero voltage vector 123, i.e., the on-off signals Up2, Vp2, and Wp2, are "off," "on," and "off" from time t1 to time t2 or from time t5 to time t6. In order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in Fig. 20, the W-phase on / off signal Wp2 may also be shifted from before adjustment.

[0071] 20 , the U-phase voltage command Vu* has a command waveform 70u1 before shifting and a command waveform 70u2 after shifting. The V-phase voltage command Vv* without shifting is a command waveform 70v, and the W-phase voltage command Vw* without shifting is a command waveform 70w. The U-phase on-off signal Up2 after shifting is an on-on signal waveform 71u. The V-phase on-off signal Vp2 without shifting is an on-on signal waveform 71v, and the W-phase on-off signal Wp2 without shifting is an on-on signal waveform 71w.

[0072] In the command waveform 70u2, the command value at the first half of the carrier Trmf is decreased compared to before the shift, and the command value at the second half of the carrier Trms is increased compared to before the shift. After the shift, the U-phase on / off signal Up2 is at the on level from time t3 to time t5. The V-phase on / off signal Vp2 is at the on level from time t1 to time t6, and the W-phase on / off signal Wp2 is at the on level from time t2 to time t4. The period from time t3 to time t4 is the zero-voltage vector period Z1 during which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and the set of elements of the on / off signal sg2 becomes the zero-voltage vector 122. The period from time t2 to time t3 is a non-zero voltage vector period in which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and the set of elements of the on / off signal sg2 becomes a non-zero voltage vector 123, as well as a current detection voltage vector period Q1 in which the detection on / off signal vector 121 is output.

[0073] A comparison of detection timing Tu1 in Fig. 19 and detection timing Tu2 in Fig. 20 reveals that detection timing Tu1 in Fig. 19 is closer to time tc3, the time when the positive peak of U-phase rotating machine current Imu appears, i.e., sign reversal timing Tsr. Furthermore, when all three-phase upper-arm on-off signals Up2, Vp2, and Wp2 are at the off level, and when all three-phase upper-arm on-off signals Up2, Vp2, and Wp2 are at the on level, the changes in phase currents Iu, Iv, and Iw are smaller than the changes in phase currents Iu, Iv, and Iw when the upper-arm on-off signals Up2, Vp2, and Wp2 of one or two of the three phases are at the on level. This also reveals that detecting U-phase rotating machine current Imu at detection timing Tu1 in Fig. 19 results in a detected current value closer to the positive peak of U-phase rotating machine current Imu than when detecting U-phase rotating machine current Imu at detection timing Tu2 in Fig. 20 . Therefore, in order to detect the current closest to the positive peak of the U-phase rotating machine current Imu, the timing determination unit 35 determines that one of the phases for detecting current in the carrier period (first current detection period Sd1) immediately before the timing of time tc3 is the U-phase.

[0074] From the above, when the start point of the carrier signal 51 is set to the peak Pp, i.e., when the cycle end of the carrier signal 51 is set to the peak Pp, the positive peaks of the currents of all phases can be detected with high accuracy by detecting the rotor current Im of the phase that has the largest absolute value among the three phase currents and is closest to the positive peak in the carrier period (first current detection period Sd1) immediately before the timing at which the positive peak of the rotor current Im of each phase appears. The detected on / off signal vector 121 that starts at the peak Pp and detects the positive peak (first detection target) of the rotor current Im with high accuracy is a set of on / off signals sg2 in which the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 is equal to the absolute value of the current of one phase of the rotor 2 that has the largest absolute value among the three phase currents and is increasing toward the positive peak (rotor current Imu in the first current detection period Sd1). Furthermore, the detected on / off signal vector 121 for detecting the first detection object with high accuracy may be expressed as follows: The detected on / off signal vector 121 for detecting the first detection object with high accuracy is a set of on / off signals sg2 such that the absolute value of the current (rotating machine current Imu in the first current detection period Sd1) flowing through the phase having the smallest absolute instantaneous value of the voltage (three-phase voltage Vuvw) supplied to the rotating machine 2 is equal to the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 immediately before the sign of the command value reverses from positive to negative at the middle of the command period Tmc (command period middle Tmcc).

[0075] When generating the detection on / off signal vector 121 that detects the first detection object with high accuracy, the control unit 4 determines the phase of the AC voltage (three-phase voltage Vuvw) whose sign determination object (the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the rotating machine 2) reverses its sign from positive to negative at the sign reversal timing Tsr as the detection object phase Pid of the phase current to be detected, and determines to detect the phase current of the detection object phase Pid in the second voltage unit interval Tru2 that is located before the sign reversal timing Tsr.

[0076] 18 shows the relationship between the high-frequency voltage command and the rotating machine current Im using a rectangular wave high-frequency voltage command as an example, but the relationship between a fundamental wave high-frequency voltage command and the rotating machine current Im is similar to that in the rectangular wave example. In the case of a fundamental wave high-frequency voltage command, the high-frequency voltage output from the power conversion unit 3 becomes a fundamental wave as shown in the phase voltage waveform 46 in FIG. 17. At the timing (time tc3) when the positive peak of the U-phase rotating machine current Imu appears, the instantaneous value of the fundamental wave (phase voltage waveform 46) of the U-phase phase voltage Vu and the instantaneous value (pulse edge passing through 0) of the fundamental wave of the U-phase high-frequency voltage command (corresponding to the command waveform 67u of the fundamental voltage command 119) are 0, and are smaller than the absolute values ​​of the instantaneous values ​​of the fundamental waves (phase voltage waveform 46) of the V-phase and W-phase phase voltages Vv and Vw and the absolute values ​​of the instantaneous values ​​of the fundamental waves of the high-frequency voltage command (corresponding to the command waveforms 67v and 67w of the fundamental voltage command 119). Therefore, since the phase difference between the three-phase voltage Vuvw of the high-frequency voltage or the voltage command Vuvw* which is the high-frequency voltage command, and the rotating machine current Im is 90°, at the timing when the positive peak of the rotating machine current Im of a certain phase appears, the instantaneous value of the quasi-fundamental wave of the phase voltage (Vu, Vv, Vw) of that phase and the instantaneous value of the quasi-fundamental wave (fundamental voltage command 119) of the high-frequency voltage command of that phase are 0, and are smaller than the absolute values ​​of the instantaneous values ​​of the quasi-fundamental wave of the phase voltages of the other phases and the absolute values ​​of the instantaneous values ​​of the quasi-fundamental wave of the high-frequency voltage command.

[0077] Next, a case where the starting point of the carrier signal 51 is the valley Pv, i.e., the cycle end of the carrier signal 51 is the valley Pv, will be described. First, FIG. 21 shows a second example of the carrier signal 51, whose starting point in the period of the carrier cycle Tc is the valley Pv, the voltage commands Vu*, Vv*, and Vw*, and the rotating machine current Im, which is the three-phase current of the rotating machine 2. Differences from FIG. 18 will be mainly described. The command waveforms 67u, 67v, and 67w of the voltage commands Vu*, Vv*, and Vw* are the same as those in FIG. 18. The rotating machine currents Imu, Imv, and Imw are also the same as those in FIG. 18. In FIG. 21, the carrier signal 51 reaches the valley Pv at times tc0, tc1, tc2, tc3, and tc4. The period from time tc3 to the time indicated by dashed line 55c is a U-phase current detection period Sdu, and the period from the time indicated by dashed line 55d to time tc4 is a U-phase current detection period Sdu. A third current detection period Sd3 is a period of the carrier cycle Tc starting at time tc3, when the sign of the command value of the voltage command sgc in the valley-start type changes from positive to negative. A fourth current detection period Sd4 is a period of the carrier cycle Tc ending at time tc4, when the sign of the command value of the voltage command sgc in the valley-start type changes from negative to positive. The U-phase current detection period Sdu from time tc3 to the time indicated by dashed line 55c is the third current detection period Sd3, and the U-phase current detection period Sdu from the time indicated by dashed line 55d to time tc4 is the fourth current detection period Sd4. While the U-phase is denoted by symbols Sdu, Sd1, and Sd2 in FIG. 21 , the same applies to the V-phase and W-phase.

[0078] 19 and 20 show cases where the starting point of the carrier signal 51 is set to peak Pp. FIG. 19 shows a case where the current detection command 120 is set to the side of sign inversion timing Tsr in one voltage unit interval Tru, while FIG. 20 shows a case where the current detection command 120 is set to the side opposite sign inversion timing Tsr in one voltage unit interval Tru. When the starting point of the carrier signal 51 is set to valley Pv, i.e., when the cycle end of the carrier signal 51 is set to valley Pv, FIG. 23 corresponds to FIG. 19, where the starting point is peak Pp, and FIG. 22 corresponds to FIG. 20, where the starting point is peak Pp. FIGS. 22 and 23 are valley-start type signal diagrams. Hereinafter, signal diagrams such as those in FIGS. 22 and 23 will be referred to as valley-start type signal explanatory diagrams as appropriate. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. 23 shows an example of the detection timing of the U-phase rotating machine current Imu when the U-phase rotating machine current Imu is detected in the carrier period (third current detection period Sd3) immediately after time tc3, which is the U-phase sign reversal timing Tsr. The U-phase voltage command Vu* has a command waveform 74u1 before shifting and a command waveform 74u2 after shifting. The V-phase voltage command Vv* without shifting is a command waveform 74v, and the W-phase voltage command Vw* without shifting is a command waveform 74w. The U-phase on-off signal Up2 after shifting is an on-on signal waveform 75u. The V-phase on-off signal Vp2 without shifting is an on-on signal waveform 75v, and the W-phase on-off signal Wp2 without shifting is an on-on signal waveform 75w.

[0079] In the command waveform 74u2, the command value at the first half of the carrier Trmf is decreased compared to before the shift, and the command value at the second half of the carrier Trms is increased compared to before the shift. After the shift, the U-phase on / off signal Up2 is at the off level from time t1 to time t5. The V-phase on / off signal Vp2 is at the off level from time t3 to time t4, and the W-phase on / off signal Wp2 is at the off level from time t2 to time t6. The period from time t3 to time t4 is the zero voltage vector period Z1 in which the on / off signals Up2, Vp2, and Wp2 are "off," "off," and "off," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time tc3 to time t1 is the zero voltage vector period Z2 in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t1 to time t2 is a non-zero voltage vector period during which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and the set of elements of the on / off signal sg2 becomes a non-zero voltage vector 123, and is also a current detection voltage vector period Q1 during which the detected on / off signal vector 121 is output. The time of the current detection voltage vector period Q1 is an adjustment amount Dsu that becomes the current detection time Tid.

[0080] The case where the U-phase rotating machine current Imu is detected in the carrier period (third current detection period Sd3) immediately after time tc3 is, for example, detection timing Tu4 in FIG. 23 . At detection timing Tu4, the U-phase rotating machine current Imu can be detected immediately after the on-off signal Up2 of the U-phase upper arm transitions from an on level to an off level. It is not a problem if detection timing Tg, such as detection timing Tu4, overlaps with a change in the on-off signal sg2 of a signal other than the target signal, because current detection is completed at detection timing Tg. This is also true in other figures. In FIG. 23 , the unadjusted on-off signal Up2 of the U-phase upper arm is shifted as indicated by arrow 54u to generate the adjusted on-off signal Up2 so that the U-phase rotating machine current Imu can be detected. The detected on-off signal vector 121 shown in FIG. 23 is a non-zero voltage vector 123 in which the on-off signals Up2, Vp2, and Wp2 are “off,” “on,” and “on,” allowing detection of the U-phase rotating machine current Imu. The current detection command 120 shown in FIG. 23 is a command having command values ​​for each phase in command waveforms 74u2, 74v, and 74w from time t1 to time t2. If the U-phase on / off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 23 is the V-phase current for which the non-zero voltage vector 123, i.e., the on / off signals Up2, Vp2, and Wp2, are "off," "on," and "off" from time t2 to time t3 or from time t4 to time t5. Therefore, in order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in FIG. 23, the W-phase on / off signal Wp2 may also be shifted from before adjustment.

[0081] On the other hand, when detecting the U-phase rotating machine current Imu in the carrier period immediately before time tc3, for example, this is detection timing Tu3 shown in FIG. 22 . At detection timing Tu3, the U-phase rotating machine current Imu can be detected by time t5, which is the time when the on-off signal Up2 of the U-phase upper arm transitions from the off level to the on level and after the elapse of the adjustment amount Dsu, which is the current detection time Tid. In FIG. 22 , the pre-adjustment on-off signal Up2 of the U-phase upper arm is shifted as indicated by arrow 54u to generate the post-adjustment on-off signal Up2, in order to enable detection of the U-phase rotating machine current Imu. If the U-phase on-off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 22 is only the W-phase current when the non-zero voltage vector 123, i.e., the on-off signals Up2, Vp2, and Wp2, are "on," "on," and "off" between time t1 and time t2 or between time t5 and time t6. In order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in Fig. 22, the V-phase on / off signal Vp2 may also be shifted from before adjustment.

[0082] 22 , the U-phase voltage command Vu* has a command waveform 72u1 before shifting and a command waveform 72u2 after shifting. The V-phase voltage command Vv* without shifting is a command waveform 72v, and the W-phase voltage command Vw* without shifting is a command waveform 72w. The U-phase on-off signal Up2 after shifting is an on-on signal waveform 73u. The V-phase on-off signal Vp2 without shifting is an on-on signal waveform 73v, and the W-phase on-off signal Wp2 without shifting is an on-on signal waveform 73w.

[0083] A comparison of detection timing Tu3 in Figure 22 and detection timing Tu4 in Figure 23 reveals that the detected current has a value closer to the positive peak of U-phase rotating machine current Imu when U-phase rotating machine current Imu is detected at detection timing Tu4 in Figure 23, i.e., the detection timing on the sign reversal timing Tsr side, than when U-phase rotating machine current Imu is detected at detection timing Tu3 in Figure 22. Therefore, if the starting point of carrier signal 51 is set to valley Pv, timing determiner 35 determines that one of the phases for detecting current in the carrier period (third current detection period Sd3) immediately after time tc3 is U-phase.

[0084] From the above, when the start point of the carrier signal 51 is set to the valley Pv, the positive peaks of the currents of all phases can be detected with high accuracy by detecting the rotor current Im of the phase that has the largest absolute value among the three phases and is closest to the positive peak in the carrier period (third current detection period Sd3) immediately after the timing at which the positive peak of the rotor current Im of each phase appears. A detected on / off signal vector 121 that starts at the valley Pv and detects the positive peak of the rotor current Im (second detection target) with high accuracy is a set of on / off signals sg2 in which the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 is equal to the absolute value of the current of one phase of the rotor 2 that has the largest absolute value among the three phases and has decreased beyond the positive peak (rotor current Imu in the third current detection period Sd3). Furthermore, the detected on / off signal vector 121 that detects the second detection target with high accuracy may be expressed as follows. The detection on / off signal vector 121 that detects the second detection target with high accuracy is a set of on / off signals sg2 such that the absolute value of the current (rotating machine current Imu in the third current detection period Sd3) flowing in the phase having the smallest absolute instantaneous value of the voltage (three-phase voltage Vuvw) supplied to the rotating machine 2 is equal to the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 immediately after the sign of the command value is reversed from positive to negative in the middle of the command period Tmc (command period middle Tmcc).

[0085] Next, a case where a current closer to the negative peak of the rotating machine current Im is detected will be described. When the timing determiner 35 determines that the U-phase is one of the phases for detecting a current in the carrier period (second current detection period Sd2) immediately after time tc4 in Fig. 18 , the timing determiner 35 determines, based on the same thinking as when detecting a current in the carrier period (first current detection period Sd1) immediately before time tc3 in Fig. 18 , that detecting the U-phase rotating machine current Imu in the carrier period (second current detection period Sd2) immediately after time tc4 allows detecting a current closer to the negative peak of the U-phase rotating machine current Imu than detecting the U-phase rotating machine current Imu in the carrier period immediately before time tc4.

[0086] FIG. 24 is an explanatory diagram of a peak-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 24 shows an example of the detection timing of the U-phase rotating machine current Imu when the U-phase rotating machine current Imu is detected during the carrier period (second current detection period Sd2) immediately after time tc4. The U-phase voltage command Vu* is represented by command waveform 76u1 before shifting and command waveform 76u2 after shifting. The V-phase voltage command Vv* without shifting is represented by command waveform 76v, and the W-phase voltage command Vw* without shifting is represented by command waveform 76w. The U-phase on-off signal Up2 after shifting is represented by on-on signal waveform 77u. The V-phase on-off signal Vp2 without shifting is represented by on-on signal waveform 77v, and the W-phase on-off signal Wp2 without shifting is represented by on-on signal waveform 77w.

[0087] In the command waveform 76u2, the command value increases from before the shift in the first half of the carrier Trmf, and decreases from before the shift in the second half of the carrier Trms. After the shift, the U-phase on / off signal Up2 is at the on level from time t1 to time t5. The V-phase on / off signal Vp2 is at the on level from time t3 to time t4, and the W-phase on / off signal Wp2 is at the on level from time t2 to time t6. The period from time t3 to time t4 is the zero voltage vector period Z1 in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time tc4 to time t1 is the zero voltage vector period Z2 in which the on / off signals Up2, Vp2, and Wp2 are "off," "off," and "off," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t1 to time t2 is a non-zero voltage vector period during which the on / off signals Up2, Vp2, and Wp2 are "on," "off," and "off," and the set of elements of the on / off signal sg2 becomes a non-zero voltage vector 123, and is also a current detection voltage vector period Q1 during which the detected on / off signal vector 121 is output. The time of the current detection voltage vector period Q1 is an adjustment amount Dsu that becomes the current detection time Tid.

[0088] The detection of the U-phase rotating machine current Imu during the carrier period (second current detection period Sd2) immediately after time tc4 is, for example, detection timing Tu6 in FIG. 24 . Detection timing Tu6 allows the U-phase rotating machine current Imu to be detected immediately after the on-off signal Up2 for the U-phase upper arm transitions from an off level to an on level. In FIG. 24 , the unadjusted on-off signal Up2 for the U-phase upper arm is shifted as indicated by arrow 54u to generate the adjusted on-off signal Up2 so that the U-phase rotating machine current Imu can be detected. The detected on-off signal vector 121 shown in FIG. 24 is a non-zero voltage vector 123 in which the on-off signals Up2, Vp2, and Wp2 are “on,” “off,” and “off,” allowing the U-phase rotating machine current Imu to be detected. The current detection command 120 shown in FIG. 24 is a command having command values ​​for each phase in the command waveforms 76u2, 76v, and 76w from time t1 to time t2. If the U-phase on / off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 24 will be only the V-phase current for which the non-zero voltage vector 123, i.e., the on / off signals Up2, Vp2, and Wp2, are "on," "off," and "on" from time t2 to time t3 or from time t4 to time t5. Therefore, in order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in FIG. 24, the W-phase on / off signal Wp2 may also be shifted from before adjustment.

[0089] From the above, when the start point of the carrier signal 51 is set to the peak Pp, the negative peaks of the currents of all phases can be detected with high accuracy by detecting the rotor current Im of the phase that has the largest absolute value among the three phases and is closest to the negative peak in the carrier period (second current detection period Sd2) immediately after the timing at which the negative peak of the rotor current Im of each phase appears. A detected on / off signal vector 121 that starts at the peak Pp and detects the negative peak of the rotor current Im (third detection target) with high accuracy is a set of on / off signals sg2 in which the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 is equal to the absolute value of the current of one phase of the rotor 2 that has the largest absolute value among the three phases and has increased beyond the negative peak (rotor current Imu in the second current detection period Sd2). Furthermore, the detected on / off signal vector 121 that detects the third detection target with high accuracy may be expressed as follows. The detection on / off signal vector 121 for detecting the third detection target with high accuracy is a set of on / off signals sg2 such that the absolute value of the current (rotating machine current Imu in the second current detection period Sd2) flowing in the phase having the smallest absolute instantaneous value of the voltage (three-phase voltage Vuvw) supplied to the rotating machine 2 is equal to the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 immediately after the sign of the command value reverses from negative to positive at the middle of the command period Tmc (command period middle Tmcc) whose starting point is the timing when the sign of the command value reverses from positive to negative.

[0090] 24 shows a detected on / off signal vector 121 for detecting the negative peak (third detection target) of the rotating machine current Im with high accuracy when the start point of the carrier signal 51 is set to the peak Pp. When the start point of the carrier signal 51 is set to the valley Pv, detecting the U-phase rotating machine current Imu in the carrier period (fourth current detection period Sd4) immediately before the timing of time tc4 in FIG. 21 allows a current closer to the negative peak of the U-phase rotating machine current Imu to be detected than detecting the U-phase rotating machine current Imu in the carrier period immediately after the timing of time tc4. Therefore, the timing determiner 35 determines that one of the phases for detecting a current in the carrier period (fourth current detection period Sd4) immediately before the timing of time tc4 is the U-phase.

[0091] FIG. 25 is an explanatory diagram of a valley-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 25 shows an example of the detection timing of the U-phase rotating machine current Imu when the U-phase rotating machine current Imu is detected during the carrier period (fourth current detection period Sd4) immediately before time tc4. The U-phase voltage command Vu* is represented by command waveform 78u1 before shifting and command waveform 78u2 after shifting. The V-phase voltage command Vv* without shifting is represented by command waveform 78v, and the W-phase voltage command Vw* without shifting is represented by command waveform 78w. The U-phase on-off signal Up2 after shifting is represented by on-on signal waveform 79u. The V-phase on-off signal Vp2 without shifting is represented by on-on signal waveform 79v, and the W-phase on-off signal Wp2 without shifting is represented by on-on signal waveform 79w.

[0092] In the command waveform 78u2, the command value increases from before the shift at the first half of the carrier Trmf, and decreases from before the shift at the second half of the carrier Trms. After the shift, the U-phase on / off signal Up2 is at the off level from time t2 to time t6. The V-phase on / off signal Vp2 is at the off level from time t1 to time t5, and the W-phase on / off signal Wp2 is at the off level from time t3 to time t4. The period from time t3 to time t4 is the zero voltage vector period Z1 in which the on / off signals Up2, Vp2, and Wp2 are "off," "off," and "off," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t6 to time tc4 is the zero voltage vector period Z2 in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t5 to time t6 is a non-zero voltage vector period during which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and the set of elements of the on / off signal sg2 becomes a non-zero voltage vector 123, and is also a current detection voltage vector period Q1 during which the detected on / off signal vector 121 is output. The time of the current detection voltage vector period Q1 is an adjustment amount Dsu that becomes the current detection time Tid.

[0093] The detection of the U-phase rotating machine current Imu during the carrier period (fourth current detection period Sd4) immediately prior to time tc4 corresponds to, for example, detection timing Tu5 in FIG. 25 . Detection timing Tu5 allows the U-phase rotating machine current Imu to be detected immediately before the on-off signal Up2 for the U-phase upper arm transitions from an off level to an on level. In FIG. 25 , the unadjusted on-off signal Up2 for the U-phase upper arm is shifted as indicated by arrow 54u to generate the adjusted on-off signal Up2 so that the U-phase rotating machine current Imu can be detected. The detected on-off signal vector 121 shown in FIG. 25 is a non-zero voltage vector 123 in which the on-off signals Up2, Vp2, and Wp2 are “off,” “on,” and “on,” enabling detection of the U-phase rotating machine current Imu. The current detection command 120 shown in FIG. 25 is a command having command values ​​for each phase in the command waveforms 78u2, 78v, and 78w from time t5 to time t6. If the U-phase on / off signal Up2 is not shifted from before adjustment, the rotating machine current Im that can be detected within the carrier period Tc shown in FIG. 25 will be only the W-phase current for which the non-zero voltage vector 123, i.e., the on / off signals Up2, Vp2, and Wp2, are "off," "off," and "on" from time t2 to time t3 or from time t4 to time t5. Therefore, in order to detect the U-phase rotating machine current Imu, it is necessary to shift the U-phase on / off signal Up2. Note that, although the U-phase on / off signal Up2 is shifted from before adjustment in FIG. 25, the V-phase on / off signal Vp2 may also be shifted from before adjustment.

[0094] From the above, when the start point of the carrier signal 51 is set to the valley Pv, the negative peaks of the currents of all phases can be detected with high accuracy by detecting the rotor current Im of the phase that has the largest absolute value among the three phases and is closest to the negative peak in the carrier period (fourth current detection period Sd4) immediately before the timing at which the negative peak of the rotor current Im of each phase appears. A detected on / off signal vector 121 that starts at the valley Pv and detects the negative peak of the rotor current Im (fourth detection target) with high accuracy is a set of on / off signals sg2 in which the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 is equal to the absolute value of the current of one phase of the rotor 2 that has the largest absolute value among the three phases and is decreasing toward the negative peak (rotor current Imu in the fourth current detection period Sd4). Furthermore, the detected on / off signal vector 121 that detects the fourth detection target with high accuracy may be expressed as follows. The detected on / off signal vector 121 that detects the fourth detection target with high accuracy is a set of on / off signals sg2 such that the absolute value of the current (rotating machine current Imu in the fourth current detection period Sd4) flowing in the phase having the smallest absolute instantaneous value of the voltage (three-phase voltage Vuvw) supplied to the rotating machine 2 is equal to the absolute value of the DC current (DC bus current Idc) detected by the current detection unit 5 just before the sign of the command value reverses from negative to positive at the middle of the command period Tmc (command period middle Tmcc) starting from the timing when the sign of the command value reverses from positive to negative.

[0095] If the starting point of the carrier signal 51 is set to the peak Pp, the timing determiner 35 sets the detection timing Tg so that the current closest to the positive peak of the U-phase rotating machine current Imu can be detected in the carrier period (first current detection period Sd1) immediately before the timing of time tc3 in Fig. 18. The detection timing Tg for detecting the U-phase rotating machine current Imu in the carrier period (first current detection period Sd1) immediately before the timing of time tc3 is, for example, the timing Tu1 in Fig. 19. If the starting point of the carrier signal 51 is set to the valley Pv, the timing determiner 35 sets the detection timing Tg so that the current closest to the positive peak of the U-phase rotating machine current Imu can be detected in the carrier period (third current detection period Sd3) immediately after the timing of time tc3 in Fig. 21. The detection timing Tg at which the U-phase rotating machine current Imu is detected in the carrier period (third current detection period Sd3) immediately after the timing of time tc3 is, for example, the timing Tu4 in FIG.

[0096] When the start point of the carrier signal 51 is set to the peak Pp, the positive peak of the rotating machine current Im of a certain phase appears at the end point (time tc3 in FIG. 18 ) of a carrier period (first current detection period Sd1) designated for detecting the positive peak of the rotating machine current Im. Therefore, by setting the detection timing Tg of the certain phase in the latter half Trms of the carrier of the certain carrier period (first current detection period Sd1), the positive peak of the rotating machine current Im of the certain phase can be detected with high accuracy. When the start point of the carrier signal 51 is set to the peak Pp, the end point of the first current detection period Sd1 is the end point of the second voltage unit interval Tru2, in which the carrier signal 51 shows a time-dependent change trend in value, increasing from the second peak (valley Pv) to the first peak (peak Pp). The end timing of the first current detection period Sd1 and the end timing of the second voltage unit interval Tru2 are the sign reversal timing Tsr, at which the sign of the voltage command sgc for one phase is reversed from positive to negative. 19, of the zero voltage vectors 122 outputted in time before (on the left side in FIG. 19) the detected on / off signal vector 121 outputted at the timing of detecting the positive peak of the rotating machine current Im, the zero voltage vector 122 closest to the detected on / off signal vector 121 is the zero voltage vector outputted near the valley Pv of the carrier signal 51. In the example of FIG. 19, the detected on / off signal vector 121 is outputted in a current detected voltage vector period Q1, and the zero voltage vector 122 that is closest to the detected on / off signal vector 121 in time before the detected on / off signal vector 121 is outputted in a zero voltage vector period Z1. The detected on / off signal vector 121 turns on the switching element 11a of the U-phase upper arm, the switching element 11d of the V-phase lower arm, and the switching element 11f of the W-phase lower arm.

[0097] 19 also shows that one of the voltage vectors of the on-off signal sg2 adjacent to the detected on-off signal vector 121 output at the detection timing Tg at which the positive peak of the rotating machine current Im is detected may be the zero voltage vector 122 (the voltage vector in the zero voltage vector period Z2 in the example of FIG. 19 ) output when the lower arms of all phases are in the on state. However, depending on the adjustment amount Ds in the first current detection period Sd1, the detected on-off signal vector 121 output at the detection timing Tg at which the positive peak of the rotating machine current Im is detected may not be adjacent to the zero voltage vector 122. For example, in FIG. 19 , if the unadjusted on-off signal Up2 for the U-phase upper arm is shifted further backward in time to generate the adjusted on-off signal Up2, the zero voltage vector period Z2 is shortened, and therefore the zero voltage vector 122 may disappear.

[0098] On the other hand, when the start point of the carrier signal 51 is set to the valley Pv, the positive peak of the rotor current Im of a certain phase appears at the start point (time tc3 in FIG. 21 ) of a carrier period (third current detection period Sd3) designated for detecting the positive peak of the rotor current Im. Therefore, by setting the detection timing Tg of the certain phase at the carrier first half Trmf of the certain carrier period (third current detection period Sd3), the positive peak of the rotor current Im of the certain phase can be detected with high accuracy. When the start point of the carrier signal 51 is set to the valley Pv, the start point of the third current detection period Sd3 is the start point of the second voltage unit interval Tru2, where the carrier signal 51 shows a time-increasing trend from the second peak (valley Pv) to the first peak (peak Pp). The start timing of the third current detection period Sd3 and the start timing of the second voltage unit interval Tru2 are the sign reversal timing Tsr, at which the sign of the voltage command sgc for one phase is reversed from positive to negative. 23, of the zero voltage vectors 122 outputted temporally (to the right in FIG. 23) after the detected on / off signal vector 121 outputted at the timing of detecting the positive peak of the rotating machine current Im, the zero voltage vector 122 closest to the detected on / off signal vector 121 is the zero voltage vector outputted near the peak Pp of the carrier signal 51. In the example of FIG. 23, the detected on / off signal vector 121 is outputted during the current detected voltage vector period Q1, and the zero voltage vector 122 temporally after the detected on / off signal vector 121 and closest to the detected on / off signal vector 121 is outputted during the zero voltage vector period Z1. The detected on / off signal vector 121 turns on the switching element 11b of the U-phase lower arm, the switching element 11c of the V-phase upper arm, and the switching element 11e of the W-phase upper arm.

[0099] 23 also shows that one of the voltage vectors of the on-off signal sg2 adjacent to the detected on-off signal vector 121 output at the detection timing Tg at which the positive peak of the rotating machine current Im is detected may be the zero voltage vector 122 (the voltage vector in the zero voltage vector period Z2 in the example of FIG. 23 ) output when the upper arms of all phases are in the on state. However, depending on the adjustment amount Ds in the third current detection period Sd3, the detected on-off signal vector 121 output at the detection timing Tg at which the positive peak of the rotating machine current Im is detected may not be adjacent to the zero voltage vector 122. For example, in FIG. 23 , if the unadjusted on-off signal Up2 for the U-phase upper arm is shifted further forward in time to generate the adjusted on-off signal Up2, the zero voltage vector period Z2 is shortened, and therefore the zero voltage vector 122 may disappear.

[0100] Similar to the case of setting the detection timing Tg to detect the positive peak of the U-phase rotating machine current Imu, the timing determiner 35 sets the detection timing Tg to detect the negative peak of the U-phase rotating machine current Imu. If the starting point of the carrier signal 51 is set to peak Pp, the timing determiner 35 sets the detection timing Tg so that the current closest to the negative peak of the U-phase rotating machine current Imu can be detected in the carrier period (second current detection period Sd2) immediately after time tc4 in Fig. 18. The detection timing Tg for detecting the U-phase rotating machine current Imu in the carrier period (second current detection period Sd2) immediately after time tc4 is, for example, the timing Tu6 in Fig. 24. If the starting point of the carrier signal 51 is the valley Pv, the timing determiner 35 sets the detection timing Tg so that the current closest to the negative peak of the U-phase rotating machine current Imu can be detected in the carrier period (fourth current detection period Sd4) immediately before time tc4 in Fig. 21. The detection timing Tg for detecting the U-phase rotating machine current Imu in the carrier period (fourth current detection period Sd4) immediately before time tc4 is, for example, the timing Tu5 in Fig. 25.

[0101] When the start point of the carrier signal 51 is set to the peak Pp, the negative peak of the rotating machine current Im of a certain phase appears at the start point (time tc4 in FIG. 18 ) of a carrier period (second current detection period Sd2) designated for detecting the negative peak of the rotating machine current Im. Therefore, by setting the detection timing Tg of the certain phase at the carrier first half Trmf of the certain carrier period (second current detection period Sd2), the negative peak of the rotating machine current Im of the certain phase can be detected with high accuracy. When the start point of the carrier signal 51 is set to the peak Pp, the start point of the second current detection period Sd2 is the start point of the first voltage unit interval Tru1, where the carrier signal 51 shows a decreasing trend over time from the first peak (peak Pp) to the second peak (valley Pv). The start timing of the second current detection period Sd2 and the start timing of the first voltage unit interval Tru1 are the sign reversal timing Tsr, at which the sign of the voltage command sgc for one phase is reversed from negative to positive. 24, among the zero voltage vectors 122 outputted in time after (to the right in FIG. 24) the detected on / off signal vector 121 outputted at the timing of detecting the negative peak of the rotating machine current Im, the zero voltage vector 122 closest to the detected on / off signal vector 121 is the zero voltage vector outputted near the valley Pv of the carrier signal 51. In the example of FIG. 24, the detected on / off signal vector 121 is outputted in the current detected voltage vector period Q1, and the zero voltage vector 122 that is closest to the detected on / off signal vector 121 in time after the detected on / off signal vector 121 is outputted in the zero voltage vector period Z1. The detected on / off signal vector 121 turns on the switching element 11a of the U-phase upper arm, the switching element 11d of the V-phase lower arm, and the switching element 11f of the W-phase lower arm.

[0102] 24 also shows that one of the voltage vectors adjacent to the detected on / off signal vector 121 output at the detection timing Tg at which the negative peak of the rotating machine current Im is detected may be the zero voltage vector 122 (the voltage vector in the zero voltage vector period Z2 in the example of FIG. 24 ) output when the lower arms of all phases are in the on state. However, depending on the adjustment amount Ds in the second current detection period Sd2, the detected on / off signal vector 121 output at the detection timing Tg at which the negative peak of the rotating machine current Im is detected may not be adjacent to the zero voltage vector 122. For example, in FIG. 24 , if the unadjusted on / off signal Up2 of the U-phase upper arm is shifted further forward in time to generate an adjusted on / off signal Up2, the zero voltage vector period Z2 is shortened, and therefore the zero voltage vector 122 may disappear.

[0103] On the other hand, when the start point of the carrier signal 51 is set to the valley Pv, the negative peak of the rotating machine current Im of a certain phase appears at the end point (time tc4 in FIG. 21 ) of the carrier period (fourth current detection period Sd4) designated for detecting the negative peak of the rotating machine current Im. Therefore, by setting the detection timing Tg of the certain phase in the latter half Trms of the carrier of the certain carrier period (fourth current detection period Sd4), the negative peak of the rotating machine current Im of the certain phase can be detected with high accuracy. When the start point of the carrier signal 51 is set to the valley Pv, the end point of the fourth current detection period Sd4 is the end point of the first voltage unit interval Tru1, during which the carrier signal 51 exhibits a time-dependent decreasing trend in value from the first peak (peak Pp) to the second peak (trough Pv). The end points of the fourth current detection period Sd4 and the first voltage unit interval Tru1 are the sign reversal timing Tsr, at which the sign of the voltage command sgc for one phase is reversed from negative to positive. In Fig. 25 , the detection timing Tg for detecting the U-phase rotating machine current Imu is the timing Tu5. As can be seen from Fig. 25 , of the zero voltage vectors 122 outputted in time before (on the left side in Fig. 25 ) the detected on / off signal vector 121 outputted at the timing of detecting the negative peak of the rotating machine current Im, the zero voltage vector 122 closest to the detected on / off signal vector 121 is the zero voltage vector outputted near the peak Pp of the carrier signal 51. In the example of Fig. 25 , the detected on / off signal vector 121 is outputted in the current detection voltage vector period Q1, and the zero voltage vector 122 closest to the detected on / off signal vector 121 in time before the detected on / off signal vector 121 is outputted in the zero voltage vector period Z1. The detected on / off signal vector 121 turns on the switching element 11b of the U-phase lower arm, the switching element 11c of the V-phase upper arm, and the switching element 11e of the W-phase upper arm.

[0104] 25 also shows that one of the voltage vectors of the on-off signal sg2 adjacent to the detected on-off signal vector 121 output at the detection timing Tg at which the negative peak of the rotating machine current Im is detected may be the zero voltage vector 122 (the voltage vector in the zero voltage vector period Z2 in the example of FIG. 25 ) output when the upper arms of all phases are in the on state. However, depending on the adjustment amount Ds in the fourth current detection period Sd4, the detected on-off signal vector 121 output at the detection timing Tg at which the negative peak of the rotating machine current Im is detected may not be adjacent to the zero voltage vector 122. For example, in FIG. 25 , if the unadjusted on-off signal Up2 of the U-phase upper arm is shifted further back in time to generate the adjusted on-off signal Up2, the zero voltage vector period Z2 is shortened, and therefore the zero voltage vector may disappear.

[0105] As described above, the timing determiner 35 determines the detection target phase Pid as follows: When the cycle end of the carrier signal 51 corresponds to the crest Pp, the timing determiner 35 determines the first special phase 125 as the detection target phase Pid in the second half (carrier second half Trms) of the first cycle period (first current detection period Sd1), which is the cycle period of the carrier signal 51 immediately before the sign of the command value of one phase of the basic voltage command 119 changes from positive to negative. Furthermore, when the cycle end of the carrier signal 51 corresponds to the crest Pp, the timing determiner 35 determines the second special phase 126 as the detection target phase Pid in the first half (carrier first half Trms) of the second cycle period (second current detection period Sd2), which is the cycle period of the carrier signal 51 immediately after the sign of the command value of one phase of the basic voltage command 119 changes from negative to positive.

[0106] The first current detection period Sd1 and the second current detection period Sd2 can be expressed as follows using the first voltage unit interval Tru1, the second voltage unit interval Tru2, and the sign reversal timing Tsr. The first current detection period Sd1 and the second current detection period Sd2 include the first voltage unit interval Tru1 and the second voltage unit interval Tru2, and are sections of one cycle of the carrier signal 51 in which the sign reversal timing Tsr coincides with the first peak (peak Pp) of the carrier signal 51. The timing determiner 35 can also be expressed as determining the detection target phase Pid as follows. When the timing of the end end of the second voltage unit interval Tru2 coincides with the sign reversal timing Tsr, the timing determiner 35 determines, as the detection target phase Pid of the phase current to be detected, the phase of the AC voltage (three-phase voltage Vuvw) whose sign of the target for sign determination (the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the rotating machine 2) reverts from positive to negative at the sign reversal timing Tsr. Furthermore, when the timing of the start end of the first voltage unit interval Tru1 is the sign reversal timing Tsr, the timing determination unit 35 determines the phase of the AC voltage (three-phase voltage Vuvw) whose sign of the target for sign determination (the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the rotating machine 2) reverses from negative to positive at the sign reversal timing Tsr as the detection target phase Pid of the phase current to be detected.

[0107] Furthermore, when the cycle end of the carrier signal 51 corresponds to the valley Pv, the timing determiner 35 determines the first special phase 125 as the detection target phase Pid in the first half (carrier first half Trmf) of the third cycle period (third current detection period Sd3), which is the cycle period of the carrier signal 51 immediately after the sign of the command value of one phase of the basic voltage command 119 changes from positive to negative. Furthermore, when the cycle end of the carrier signal 51 corresponds to the valley Pv, the timing determiner 35 determines the second special phase 126 as the detection target phase Pid in the second half (carrier second half Trms) of the fourth cycle period (fourth current detection period Sd4), which is the cycle period of the carrier signal 51 immediately before the sign of the command value of one phase of the basic voltage command 119 changes from negative to positive.

[0108] The third current detection period Sd3 and the fourth current detection period Sd4 can be expressed as follows using the first voltage unit interval Tru1, the second voltage unit interval Tru2, and the sign reversal timing Tsr. The third current detection period Sd3 and the fourth current detection period Sd4 have the second voltage unit interval Tru2 and the first voltage unit interval Tru1, and are periods of one cycle of the carrier signal 51 in which the sign reversal timing Tsr coincides with the second peak (trough Pv) of the carrier signal 51. The timing determiner 35 can also be expressed as determining the detection target phase Pid as follows. When the timing of the start end of the second voltage unit interval Tru2 coincides with the sign reversal timing Tsr, the timing determiner 35 determines the phase of the AC voltage (three-phase voltage Vuvw) whose sign is to be determined (the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the rotating machine 2) at the sign reversal timing Tsr to be the detection target phase Pid of the phase current to be detected. Furthermore, when the timing of the end end of the first voltage unit interval Tru1 coincides with the sign reversal timing Tsr, the timing determiner 35 determines the phase of the AC voltage (three-phase voltage Vuvw) whose sign is to be determined (the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the rotating machine 2) at the sign reversal timing Tsr to be the detection target phase Pid of the phase current to be detected.

[0109] The timing determiner 35 sets the current detection timing, i.e., the detection timing Tg, as follows: When the cycle end of the carrier signal 51 corresponds to the crest Pp, the timing determiner 35 sets the current detection timing (detection timing Tg) for detecting the current of the first special phase 125 in the second half (carrier second half Trms) of the first cycle period (first current detection period Sd1) to the end of the first cycle period (first current detection period Sd1) or immediately before the detected on / off signal vector 121 changes to the zero voltage vector 122. When the cycle end of the carrier signal 51 corresponds to the crest Pp, the timing determiner 35 sets the current detection timing (detection timing Tg) for detecting the current of the second special phase 126 in the first half (carrier first half Trmf) of the second cycle period (second current detection period Sd2) to immediately after the minimum value of the current detection time Tid has elapsed since the detected on / off signal vector 121 was output to the power converter 3.

[0110] The timing determination unit 35 can also be expressed as setting the current detection timing, i.e., the detection timing Tg, as follows: The switching commands (on / off signals sg2) to the multiple switching elements 11a to 11f based on the adjustment voltage command sgca that makes the DC current (DC bus current Idc) zero are set as zero switching commands (zero voltage vectors 122), and the switching commands (on / off signals sg2) to the multiple switching elements 11a to 11f based on the adjustment voltage command sgca that makes the DC current (DC bus current Idc) not zero are set as non-zero switching commands (non-zero voltage vectors 123). The timing determination unit 35 sets the current detection timing (detection timing Tg) for detecting the current of the detection target phase Pid in the second voltage unit interval Tru2 of the first current detection period Sd1 to immediately before the switching command (on / off signal sg2) is changed from a non-zero switching command (non-zero voltage vector 123) to a zero switching command (zero voltage vector 122) based on the adjustment voltage command sgca and the carrier signal 51, and to the end end of the second voltage unit interval Tru2. Furthermore, the timing determination unit 35 sets the current detection timing (detection timing Tg) for detecting the current of the detection target phase Pid in the first voltage unit section Tru1 of the second current detection period Sd2 to immediately after the minimum value of the current detection time Tid during which the current of the detection target phase Pid is reflected in the DC current (DC bus current Idc) has elapsed, after the switching command (on / off signal sg2) changes from a zero switching command (zero voltage vector 122) to a non-zero switching command (non-zero voltage vector 123), based on the adjustment voltage command sgca and the carrier signal 51.

[0111] Furthermore, when the cycle end of the carrier signal 51 is the valley Pv, the timing determiner 35 sets the current detection timing (detection timing Tg) for detecting the current of the first special phase 125 in the first half (carrier first half Trmf) of the third cycle period (third current detection period Sd3) to immediately after the minimum value of the current detection time Tid has elapsed since the detected on / off signal vector 121 was output to the power converter 3. Furthermore, when the cycle end of the carrier signal 51 is the valley Pv, the timing determiner 35 sets the current detection timing (detection timing Tg) for detecting the current of the second special phase 126 in the second half (carrier second half Trms) of the fourth cycle period (fourth current detection period Sd4) to the ending end of the fourth cycle period (fourth current detection period Sd4) or immediately before the detected on / off signal vector 121 is changed to the zero voltage vector 122.

[0112] The timing determiner 35 can also be expressed as setting the current detection timing, i.e., the detection timing Tg, as follows: In the second voltage unit interval Tru2 of the third current detection period Sd3, the timing determiner 35 sets the current detection timing (detection timing Tg) for detecting the current of the detection target phase Pid to immediately after the minimum value of the current detection time Tid during which the current of the detection target phase Pid is reflected in the DC current (DC bus current Idc) has elapsed after the switching command (on / off signal sg2) changes from a zero switching command (zero voltage vector 122) to a non-zero switching command (non-zero voltage vector 123) based on the adjustment voltage command sgca and the carrier signal 51. In addition, the timing determination unit 35 sets the current detection timing (detection timing Tg) for detecting the current of the detection target phase Pid in the first voltage unit interval Tru1 of the fourth current detection period Sd4 to immediately before the switching command (on / off signal sg2) is changed from a non-zero switching command (non-zero voltage vector 123) to a zero switching command (zero voltage vector 122) based on the adjustment voltage command sgca and the carrier signal 51, or to the end end of the first voltage unit interval Tru1.

[0113] When the cycle end of carrier signal 51 forms a peak Pp, adjustment amount determiner 36 determines the phase to be shifted, i.e., adjustment target phase Dp, in order to detect the current closest to the positive peak of U-phase rotating machine current Imu at detection timing Tu1 in Fig. 19 determined by timing determiner 35, during the carrier period (first current detection period Sd1) immediately before time tc3 in Fig. 18 , and calculates the adjustment amount Ds required for adjustment target phase Dp. Voltage command adjuster 39 outputs adjustment voltage command sgca adjusted based on the adjustment target phase Dp and adjustment amount Ds determined by adjustment amount determiner 36, and PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 19, the adjustment amount determination unit 36 ​​sets the phase to be adjusted Dp to the U phase and the adjustment amount Ds to the current detection time Tid, so the PWM signal generation unit 33 generates an on / off signal Up2 for the U phase by shifting the on / off signal Up2 before adjustment of the U phase backward in time by the current detection time Tid within the cycle period of the carrier signal 51 (first current detection period Sd1).

[0114] Similarly, when the cycle end of carrier signal 51 forms a peak Pp, adjustment amount determiner 36 determines the phase that must be shifted, i.e., the adjustment target phase Dp, in order to detect the current closest to the negative peak of U-phase rotating machine current Imu at detection timing Tu6 in Fig. 24 determined by timing determiner 35, during the carrier period (second current detection period Sd2) immediately after time tc4 in Fig. 18, and calculates the adjustment amount Ds required for the adjustment target phase Dp. Voltage command adjuster 39 outputs an adjustment voltage command sgca adjusted based on the adjustment target phase Dp and adjustment amount Ds determined by adjustment amount determiner 36, and PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 24, the adjustment amount determination unit 36 ​​sets the phase to be adjusted Dp to the U phase and the adjustment amount Ds to the current detection time Tid, so the PWM signal generation unit 33 generates an on / off signal Up2 for the U phase by shifting the pre-adjustment on / off signal Up2 for the U phase forward in time within the cycle period of the carrier signal 51 (second current detection period Sd2) by the current detection time Tid.

[0115] When the cycle end of carrier signal 51 is at valley Pv, adjustment amount determiner 36 determines the phase to be shifted, i.e., adjustment target phase Dp, in order to detect the current closest to the positive peak of U-phase rotating machine current Imu at detection timing Tu4 in Fig. 23 determined by timing determiner 35, in the carrier period (third current detection period Sd3) immediately after time tc3 in Fig. 21 , and calculates the adjustment amount Ds required for adjustment target phase Dp. Voltage command adjuster 39 outputs adjustment voltage command sgca adjusted based on the adjustment target phase Dp and adjustment amount Ds determined by adjustment amount determiner 36, and PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 23, the adjustment amount determination unit 36 ​​sets the phase to be adjusted Dp to the U phase and the adjustment amount Ds to the current detection time Tid, so the PWM signal generation unit 33 generates an on / off signal Up2 for the U phase by shifting the on / off signal Up2 before adjustment of the U phase forward in time by the current detection time Tid within the cycle period of the carrier signal 51 (third current detection period Sd3).

[0116] Similarly, when the cycle end of carrier signal 51 is at valley Pv, adjustment amount determiner 36 determines the phase to be shifted, i.e., adjustment target phase Dp, in order to detect the current closest to the negative peak in U-phase rotating machine current Imu at detection timing Tu5 in Fig. 25 determined by timing determiner 35, in the carrier period (fourth current detection period Sd4) immediately before time tc4 in Fig. 21 , and calculates the adjustment amount Ds required for adjustment target phase Dp. Voltage command adjuster 39 outputs adjustment voltage command sgca adjusted based on the adjustment target phase Dp and adjustment amount Ds determined by adjustment amount determiner 36, and PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 25, the adjustment amount determination unit 36 ​​sets the phase to be adjusted Dp to the U phase and the adjustment amount Ds to the current detection time Tid, so the PWM signal generation unit 33 generates an on / off signal Up2 for the U phase by shifting the pre-adjustment on / off signal Up2 for the U phase backward in time by the current detection time Tid within the cycle period of the carrier signal 51 (fourth current detection period Sd4).

[0117] At the detection timing Tg determined as described above, the phase current output unit 31 outputs the U-phase phase current Iu, thereby making it possible to detect the positive and negative peaks of the U-phase rotating machine current Imu with high accuracy.

[0118] In addition, for the V-phase and W-phase, the phase current output unit 31 outputs the V-phase phase current Iv and the W-phase phase current Iw at the detection timing Tg determined based on the same concept as for the U-phase, thereby making it possible to detect the positive and negative peaks of the V-phase rotating machine current Imv and the W-phase rotating machine current Imw with high accuracy.

[0119] The timing determiner 35 only needs to determine the detection target phase Pid and the detection timing Tg for detecting the positive peak and the negative peak of the rotating machine current Im of each phase, and the rotating machine current Im of any phase may be detected at any timing during a period of the carrier cycle Tc that the timing determiner 35 has not specified as the detection target phase Pid and the detection timing Tg for detecting the positive peak or the negative peak of the rotating machine current Im of each phase. That is, in the example of Fig. 18 , for example, during the period of the carrier cycle Tc immediately before time tc1 and the period of the carrier cycle Tc immediately after time tc1, the U-phase rotating machine current Imu and the V-phase rotating machine current Imv may be detected at any timing, or the U-phase rotating machine current Imu and the W-phase rotating machine current Imw may be detected at any timing.

[0120] During a period of the carrier cycle Tc that the timing determination unit 35 has not specified as the detection target phase Pid and detection timing Tg for detecting the positive or negative peak of the rotating machine current Im of each phase, the phase and detection timing Tg for detecting the rotating machine current Im can be arbitrarily set, thereby enabling current detection and pulse shifting for purposes other than detecting the peak of the rotating machine current Im during the period of the carrier cycle Tc. Such purposes include, for example, reducing distortion of the detected current.

[0121] A third example of the operation of inductance measurement device 1 will be described using Figures 26 and 27, and a fourth example of the operation of inductance measurement device 1 will be described using Figures 28 and 29. Figure 26 shows an example where the cycle end of carrier period Tc of carrier signal 51 is a peak Pp, and Figure 28 shows an example where the cycle end of carrier period Tc of carrier signal 51 is a valley Pv. The operations of timing determination unit 35, voltage command adjustment unit 39, PWM signal generation unit 33, adjustment amount determination unit 36, and phase current output unit 31 in embodiment 1 will be mainly described.

[0122] If the power conversion unit 3 is a three-phase inverter as shown in FIG. 3 , setting the command period Tmc to 3n times the carrier period Tc allows for even generation of AC voltage commands, thereby enabling highly accurate current flow without distortion in any particular phase. Here, n is a natural number. Furthermore, since the voltage command generation period and the carrier period are synchronized for all phases, current acquisition timing for all phases occurs evenly in time, enabling stable current detection. If the number of phases of AC power supplied by the power conversion unit 3 to an inductive load such as the rotating machine 2 is m, the command period Tmc can be set to mn times the carrier period Tc. Here, n is a natural number. In this case, too, the AC voltage commands can be evenly generated, allowing for highly accurate current flow without distortion in any particular phase. Current acquisition timing for all phases occurs evenly in time, enabling stable current detection. Here, the effects of setting the power conversion unit 3 to a three-phase inverter and the command period Tmc to 6 times the carrier period Tc are described in detail.

[0123] In FIGS. 26 and 28 , the voltage command calculation unit 32 outputs the components of the voltage command vector Vuvw*, which is a high-frequency voltage command expressed as a vector, i.e., the voltage commands Vu*, Vv*, and Vw*, as rectangular wave voltages with a 120° phase difference between each phase and equal voltage amplitude for each phase. Furthermore, the command period Tmc, which is the period of the voltage commands Vu*, Vv*, and Vw*, is six times the carrier period Tc, unlike in FIGS. 18 and 21 . The rotating machine current period Tmi, like the command period Tmc, is six times the carrier period Tc. The period from time tc1 to time tc4 in FIGS. 26 and 28 corresponds to the command phase difference Δθ for one phase of the voltage command sgc, and the command phase difference Δθ is 90°. The period from time tc7 to time tc10 in FIGS. 26 and 28 corresponds to the command phase difference Δθ for one phase of the voltage command sgc, and the command phase difference Δθ is 90°. Note that carrier period 81a, carrier period 81b, and carrier period 81c correspond to the first carrier period, second carrier period, and third carrier period in Fig. 26, respectively. Also, carrier period 81d, carrier period 81e, and carrier period 81f correspond to the first carrier period, second carrier period, and third carrier period in Fig. 28, respectively.

[0124] As described above, the voltage commands Vu*, Vv*, and Vw* having command waveforms 80u, 80v, and 80w are three-phase voltage commands sgc in which the three-phase voltages supplied to the rotating machine 2 are quasi-fundamental waves, i.e., the fundamental voltage command 119. The fundamental voltage command 119 generates a fundamental wave current in the rotating machine 2. When the voltage command Vu* is the fundamental wave, the positive peak of the command value appears at time tc1, and the negative peak of the command value appears at time tc7. In the command waveform 80u of the voltage command Vu*, which is a rectangular wave, time tc1 is the middle time of the positive command value period, and time tc7 is the middle time of the negative command value period. During the command period Tmc, the positive command value period of the voltage command Vu* is the period from time tc0a to time tc4, and the negative command value period of the voltage command Vu* is the period from time tc4 to time tc10.

[0125] 26 , a case will be described in which the starting point of the carrier signal 51 is set to peak Pp, i.e., the cycle end of the carrier signal 51 is set to peak P. The timing determination unit 35 determines that the positive peak of the U-phase rotating machine current Imu will appear at time tc4, which is 90° delayed from time tc1, and that the negative peak of the U-phase rotating machine current Imu will appear at time tc10, which is 90° delayed from time tc7. In order to detect values ​​as close as possible to the positive and negative peaks of the U-phase rotating machine current Imu that appear at times tc4 and tc10, the timing determination unit 35 determines that one of the phases for detecting current during the period of the carrier cycle Tc immediately before time tc4, i.e., the first current detection period Sd1, will be the U-phase, and determines that one of the phases for detecting current during the period of the carrier cycle Tc immediately after time tc10, i.e., the second current detection period Sd2, will be the U-phase. 26 corresponds to the first current detection period Sd1 of the U phase, and carrier period 81c corresponds to the second current detection period Sd2 of the U phase. Note that carrier period 81b is a period that includes the middle time of the negative command value period in the U phase.

[0126] At this time, the timing determiner 35 compares the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately before time tc4, i.e., the first current detection period Sd1, with the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately after time tc4, and determines in which case a current closer to the positive peak of the U-phase rotating machine current Imu can be detected. In the example of Fig. 26, the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately before time tc4, i.e., the first current detection period Sd1, allows a current closer to the positive peak of the U-phase rotating machine current Imu to be detected than the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately before time tc4, and therefore determines the U-phase to be one of the phases for which current is detected during the period of the carrier cycle Tc immediately before time tc4, i.e., the first current detection period Sd1.

[0127] Similarly, the timing determiner 35 compares the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately before time tc10 with the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately after time tc10, i.e., the second current detection period Sd2, to determine in which case a current closer to the negative peak of the U-phase rotating machine current Imu can be detected. In the example of Fig. 26, the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately after time tc10, i.e., the second current detection period Sd2, allows a current closer to the negative peak of the U-phase rotating machine current Imu to be detected than the case where the U-phase rotating machine current Imu is detected during the period of the carrier cycle Tc immediately after time tc10, i.e., the second current detection period Sd2. Therefore, the timing determiner 35 determines that the U-phase is one of the phases for which current is detected during the period of the carrier cycle Tc immediately after time tc10, i.e., the second current detection period Sd2.

[0128] 28 , if the starting point of the carrier signal 51 is set to the valley Pv, i.e., if the cycle end of the carrier signal 51 is set to the valley Pv, then, for the U phase in the fourth example of operation of the inductance measurement device 1, one of the phases in which current is detected during the period of the carrier cycle Tc immediately after the timing of time tc4, i.e., the third current detection period Sd3, is determined as the U phase, and one of the phases in which current is detected during the period of the carrier cycle Tc immediately before the timing of time tc10, i.e., the fourth current detection period Sd4, is determined as the U phase. In the fourth example of operation of the inductance measurement device 1, the method for determining one of the phases in which current is detected as the U phase is the same as the method for determining the U phase in the third example of operation of the inductance measurement device 1. The period of the carrier cycle Tc immediately before time tc4 is compared with the period of the carrier cycle Tc immediately after time tc4, and one of the phases for which current is detected in the third current detection period Sd3 immediately after time tc4 is determined to be the U-phase. The period of the carrier cycle Tc immediately before time tc10 is compared with the period of the carrier cycle Tc immediately after time tc10, and one of the phases for which current is detected in the fourth current detection period Sd4 immediately before time tc4 is determined to be the U-phase. Carrier period 81e in FIG. 28 corresponds to the third current detection period Sd3 of the U-phase, and carrier period 81f in FIG. 28 corresponds to the fourth current detection period Sd4 of the U-phase.

[0129] 26 and 28 is the command cycle middle point Tmcc, which is the middle of the command cycle Tmc of the U phase. As described above, in the first special phase 125, the sign of the command value of the basic voltage command 119 changes from positive to negative, so time tc4 in Figures 26 and 28 is the time when the U phase is determined to be the first special phase 125. In the second special phase 126, the sign of the command value of the basic voltage command 119 changes from negative to positive, so time tc10 in Figures 26 and 28 is the time when the U phase is determined to be the second special phase 126.

[0130] 26 and 28, when the voltage command Vv* is a fundamental wave, the positive peak of the command value appears at time tc5, and the negative peaks of the command value appear at time tc0 and time tc11. In a rectangular command waveform 80v of the voltage command Vv*, time tc5 is the intermediate time of the positive command value period, and times tc0 and tc11 are the intermediate times of the negative command value period. During one command cycle Tmc, the positive command value period of the voltage command Vv* is the period from time tc2 to time tc8, and the negative command value period of the voltage command Vv* is the period from time tc0b to time tc2.

[0131] If the starting point of the carrier signal 51 is set to peak Pp, the timing determination unit 35 determines that the positive peak of the V-phase rotating machine current Imv will appear at time tc8, which is 90° delayed from time tc5, and that the negative peak of the V-phase rotating machine current Imv will appear at time tc2, which is 90° delayed from time tc0. In order to detect values ​​as close as possible to the positive and negative peaks of the V-phase rotating machine current Imv that appear at time tc8 and time tc2, the timing determination unit 35 determines that one of the phases for detecting current in the period of the carrier cycle Tc immediately before time tc8, i.e., the first current detection period Sd1, will be the V-phase, and determines that one of the phases for detecting current in the period of the carrier cycle Tc immediately after time tc2, i.e., the second current detection period Sd2, will be the V-phase. The carrier period 81b in FIG. 26 corresponds to the first current detection period Sd1 of the V phase, and the carrier period 81a in FIG. 26 corresponds to the second current detection period Sd2 of the V phase.

[0132] Note that the description of the V-phase in the third example of operation of the inductance measurement device 1 is for the case where the starting point of the carrier signal 51 is set to be the peak Pp. When the starting point of the carrier signal 51 is set to be the valley Pv as shown in Figure 28 , i.e., in the fourth example of operation of the inductance measurement device 1, the timing determination unit 35 determines the V-phase to be one of the phases for detecting current during the period of the carrier cycle Tc immediately after time tc8, i.e., the third current detection period Sd3, and determines the V-phase to be one of the phases for detecting current during the period of the carrier cycle Tc immediately before time tc2, i.e., the fourth current detection period Sd4. Carrier period 81f in Figure 28 corresponds to the third current detection period Sd3 of the V-phase, and carrier period 81d in Figure 28 corresponds to the fourth current detection period Sd4 of the V-phase.

[0133] Furthermore, when the starting point of carrier signal 51 is peak Pp and voltage command Vw* is a fundamental wave, the positive peak of the command value appears at time tc9 and the negative peak of the command value appears at time tc3. In command waveform 80w of voltage command Vw*, which is a rectangular wave, time tc9 is the middle time of the positive command value period and time tc3 is the middle time of the negative command value period. During one command cycle Tmc, the positive command value period of voltage command Vw* is the period from time tc6 to time tc12, and the negative command value period of voltage command Vw* is the period from time tc / 2 after time tc0 to time tc6.

[0134] The timing determination unit 35 determines that the positive peak of the W-phase rotating machine current Imw will appear at time tc12, which is 90° delayed from time tc9, and that the negative peak of the W-phase rotating machine current Imw will appear at time tc6, which is 90° delayed from time tc3. In order to detect values ​​as close as possible to the positive and negative peaks of the W-phase rotating machine current Imw that appear at times tc12 and tc6, the timing determination unit 35 determines that one of the phases for detecting current during the period of the carrier cycle Tc immediately before time tc12, i.e., the first current detection period Sd1, will be the W-phase, and determines that one of the phases for detecting current during the period of the carrier cycle Tc immediately after time tc6, i.e., the second current detection period Sd2, will be the W-phase. Carrier period 81b in FIG. 26 corresponds to the second current detection period Sd2 of the W-phase, and carrier period 81c in FIG. 26 corresponds to the first current detection period Sd1 of the W-phase.

[0135] Note that the description of the W-phase in the third example of operation of the inductance measurement device 1 is for the case where the starting point of the carrier signal 51 is set to the peak Pp. When the starting point of the carrier signal 51 is set to the valley Pv as shown in Fig. 28 , i.e., in the fourth example of operation of the inductance measurement device 1, the timing determination unit 35 determines the W-phase as one of the phases for detecting current during the period of the carrier cycle Tc immediately after the timings of tc0c and tc12, i.e., the third current detection period Sd3, and determines the W-phase as one of the phases for detecting current during the period of the carrier cycle Tc immediately before the timing of tc6, i.e., the fourth current detection period Sd4. Carrier period 81d in Fig. 28 corresponds to the third current detection period Sd3 of the W-phase, and carrier period 81e in Fig. 28 corresponds to the fourth current detection period Sd4 of the W-phase.

[0136] In FIG. 26 , the period of the carrier cycle Tc immediately before time tc4 and the period of the carrier cycle Tc immediately after time tc2 are the same period, and the carrier period 81a in FIG. 26 corresponds to this period of the carrier cycle Tc. The timing determination unit 35 sets the detection timing Tu of the U-phase during the carrier period 81a so that a value as close as possible to the positive peak of the U-phase rotating machine current Imu can be detected, and sets the detection timing Tv of the V-phase so that a value as close as possible to the negative peak of the V-phase rotating machine current Imv can be detected. The detection timing Tu of the U-phase during the carrier period 81a is, for example, the detection timing Tu in FIG. 27 , and the detection timing Tv of the V-phase is, for example, the detection timing Tv in FIG. 27 . The detection timing Tv corresponds to the detection timing Tgf at which the rotating machine current Im is detected during the first carrier half Trmf of the carrier period Tc, and the detection timing Tu corresponds to the detection timing Tgs at which the rotating machine current Im is detected during the second carrier half Trms of the carrier period Tc.

[0137] FIG. 27 is an explanatory diagram of a peak-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 27 shows an example of detection timing Tu, in which the U-phase rotating machine current Imu is detected during the carrier period (first current detection period Sd1) immediately before time tc4, and detection timing Tv, in which the V-phase rotating machine current Imv is detected during the carrier period (second current detection period Sd2) immediately after time tc2. The U-phase voltage command Vu* is represented by command waveform 82u1 before shifting and command waveform 82u2 after shifting. The V-phase voltage command Vv* without shifting is represented by command waveform 82v, and the W-phase voltage command Vw* without shifting is represented by command waveform 82w. The U-phase on-off signal Up2 after shifting is represented by on-on signal waveform 83u. The V-phase on / off signal Vp2 without shift processing has an on / on signal waveform 83v, and the W-phase on / off signal Wp2 without shift processing has an on / on signal waveform 83w.

[0138] In the command waveform 82u2, the command value at the first half of the carrier Trmf is decreased compared to before the shift, and the command value at the second half of the carrier Trms is increased compared to before the shift. After the shift, the U-phase on / off signal Up2 is at the on level from time t2 to time t6. The V-phase on / off signal Vp2 is at the on level from time t1 to time t5, and the W-phase on / off signal Wp2 is at the on level from time t3 to time t4. The period from time t3 to time t4 is the zero voltage vector period Z1 in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t6 to time tc4 is the zero voltage vector period Z2s in which the on / off signals Up2, Vp2, and Wp2 are "off," "off," and "off," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time tc2 to time t1 is a zero voltage vector period Z2f during which the on-off signals Up2, Vp2, and Wp2 are "off," "off," and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t5 to time t6 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "on," "off," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q1s during which the U-phase detected on-off signal vector 121s is output. The period from time t1 to time t2 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "off," "on," and "off," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q1f during which the V-phase detected on-off signal vector 121f is output. The "s" at the end of the symbols 120s, 121s, Q1s, Z2s, Dss, and Tgs in Figures 27 and 29 indicates that they are set to or occur in the second half of the carrier Trms. The "f" at the end of the symbols 120f, 121f, Q1f, Z2f, Dsf, and Tgf in Figures 27 and 29 indicates that they are set to or occur in the first half of the carrier Trmf.

[0139] During the current detection voltage vector period Q1s, a current detection command 120s is output such that the voltage command vector Vuvw* detects the U-phase rotating machine current Imu. The duration of the current detection voltage vector period Q1s is an adjustment amount Dss that corresponds to the current detection time Tid. During the current detection voltage vector period Q1f, a current detection command 120f is output such that the voltage command vector Vuvw* detects the V-phase rotating machine current Imv. The duration of the current detection voltage vector period Q1f is an adjustment amount Dsf that corresponds to the current detection time Tid.

[0140] When detecting the U-phase rotating machine current Imu in the carrier period (first current detection period Sd1) immediately before time tc4, the current is detected at, for example, detection timing Tu corresponding to detection timing Tgs in FIG. 27 . At detection timing Tu, the U-phase rotating machine current Imu can be detected immediately before the on / off signal Up2 for the U-phase upper arm transitions from on level to off level. When detecting the V-phase rotating machine current Imv in the carrier period (second current detection period Sd2) immediately after time tc2, the current is detected at, for example, detection timing Tv corresponding to detection timing Tgf in FIG. 27 . At detection timing Tv, the V-phase rotating machine current Imv can be detected immediately after the on / off signal Vp2 for the V-phase upper arm transitions from off level to on level. In Figure 27, the on / off signal Up2 before adjustment of the U-phase upper arm is shifted as indicated by arrow 54u to generate the on / off signal Up2 so that the U-phase rotating machine current Imu and the V-phase rotating machine current Imv can be detected.

[0141] The detected on / off signal vector 121s shown in FIG. 27 is a non-zero voltage vector 123 in which the on / off signals Up2, Vp2, and Wp2 are "on," "off," and "off," and in which the U-phase rotating machine current Imu can be detected. The current detection command 120s shown in FIG. 27 is a command having command values ​​for each phase in the command waveforms 82u2, 82v, and 82w from time t5 to time t6. The detected on / off signal vector 121f shown in FIG. 27 is a non-zero voltage vector 123 in which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "off," and in which the V-phase rotating machine current Imv can be detected. The current detection command 120f shown in FIG. 27 is a command having command values ​​for each phase in the command waveforms 82u2, 82v, and 82w from time t1 to time t2.

[0142] From the above, as in the third example of the operation of the inductance measurement device 1, if the voltage commands Vu*, Vv*, and Vw* are rectangular wave voltages with a 120° phase difference between the phases, a command period Tmc six times the carrier period Tc, and equal voltage amplitudes for each phase, and the starting point of the carrier signal 51 is set to the peak Pp, peaks of the rotating machine current Im for two phases can be detected during the predetermined carrier period Tc, which is a predetermined cycle period. The predetermined carrier period Tc corresponds to the first current detection period Sd1 for one phase and the second current detection period Sd2 for the other phase. The carrier period 81a in FIG. 26 corresponds to the first current detection period Sd1 for the U phase and the second current detection period Sd2 for the V phase. That is, the carrier period 81a in FIG. 26 corresponds to the predetermined cycle period in which the first current detection period Sd1 and the second current detection period Sd2 are simultaneously realized. In the first half of the carrier Trmf of the carrier period 81a, a detection timing Tgf is set for detecting the negative peak of the V-phase rotating machine current Imv corresponding to the second current detection period Sd2, and in the second half of the carrier Trms, a detection timing Tgs is set for detecting the positive peak of the U-phase rotating machine current Imu, which corresponds to the first current detection period Sd1 and is a phase different from the first half of the carrier Trmf.

[0143] The carrier period 81b in FIG. 26 corresponds to the first current detection period Sd1 in the V-phase and the second current detection period Sd2 in the W-phase. That is, the carrier period 81b in FIG. 26 corresponds to a predetermined cycle period in which the first current detection period Sd1 and the second current detection period Sd2 are simultaneously realized. The detection timing Tgf for detecting the negative peak of the W-phase rotor current Imw corresponding to the second current detection period Sd2 is set in the carrier first half Trmf of the carrier period 81b. The detection timing Tgs for detecting the positive peak of the V-phase rotor current Imv corresponding to the first current detection period Sd1 is set in the carrier second half Trms. The carrier period 81c in FIG. 26 corresponds to the first current detection period Sd1 in the W-phase and the second current detection period Sd2 in the U-phase. That is, the carrier period 81c in FIG. 26 corresponds to the first current detection period Sd1 and the second current detection period Sd2 are simultaneously realized. In the first half of the carrier Trmf of the carrier period 81c, a detection timing Tgf is set for detecting the negative peak of the U-phase rotating machine current Imu, which corresponds to the second current detection period Sd2, and in the second half of the carrier Trms, a detection timing Tgs is set for detecting the positive peak of the W-phase rotating machine current Imw, which corresponds to the first current detection period Sd1 and is a phase different from the first half of the carrier Trmf.

[0144] The detection timings Tgf and Tgs will be described when the starting point of the carrier signal 51 is the valley Pv. In FIG. 28 , the period of the carrier cycle Tc immediately after time tc4 and the period of the carrier cycle Tc immediately before time tc6 are the same period, and the carrier period 81e in FIG. 28 corresponds to this period of the carrier cycle Tc. The timing determination unit 35 sets the U-phase detection timing Tu in the carrier period 81e so that a value as close as possible to the positive peak of the U-phase rotating machine current Imu can be detected, and sets the W-phase detection timing Tw so that a value as close as possible to the negative peak of the W-phase rotating machine current Imw can be detected. The U-phase detection timing Tu in the carrier period 81e is, for example, the detection timing Tu in FIG. 29 , and the W-phase detection timing Tw is, for example, the detection timing Tw in FIG. 29 . The detection timing Tu corresponds to the detection timing Tgf at which the rotating machine current Im is detected in the first half of the carrier Trmf of the carrier period Tc, and the detection timing Tw corresponds to the detection timing Tgs at which the rotating machine current Im is detected in the second half of the carrier Trms of the carrier period Tc.

[0145] FIG. 29 is an explanatory diagram of a valley-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 29 shows an example of detection timing Tu, at which the U-phase rotating machine current Imu is detected in the carrier period (third current detection period Sd3) immediately after time tc4, and detection timing Tw, at which the W-phase rotating machine current Imw is detected in the carrier period (fourth current detection period Sd4) immediately before time tc6. The U-phase voltage command Vu* is represented by command waveform 104u1 before shifting and command waveform 104u2 after shifting. The V-phase voltage command Vv* without shifting is represented by command waveform 104v, and the W-phase voltage command Vw* without shifting is represented by command waveform 104w. The U-phase on-off signal Up2 after shifting is represented by on-on signal waveform 105u. The V-phase on / off signal Vp2 without shift processing has an on / on signal waveform 105v, and the W-phase on / off signal Wp2 without shift processing has an on / on signal waveform 105w.

[0146] In the command waveform 104u2, the command value decreases from before the shift in the first half of the carrier Trmf, and increases from before the shift in the second half of the carrier Trms. After the shift, the U-phase on / off signal Up2 is at the off level from time t1 to time t5. The V-phase on / off signal Vp2 is at the off level from time t3 to time t4, and the W-phase on / off signal Wp2 is at the off level from time t2 to time t6. The period from time t3 to time t4 is the zero voltage vector period Z1 in which the on / off signals Up2, Vp2, and Wp2 are "off," "off," and "off," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time t6 to time tc6 is the zero voltage vector period Z2s in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on / off signal sg2 becomes the zero voltage vector 122. The period from time tc4 to time t1 is a zero voltage vector period Z2f during which the on-off signals Up2, Vp2, and Wp2 are "on," "on," and "on," and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t5 to time t6 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "on," "on," and "off," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q1s during which the W-phase detected on-off signal vector 121s is output. The period from time t1 to time t2 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q1f during which the U-phase detected on-off signal vector 121f is output.

[0147] During the current detection voltage vector period Q1s, a current detection command 120s is output such that the voltage command vector Vuvw* detects the W-phase rotating machine current Imw. The duration of the current detection voltage vector period Q1s is the adjustment amount Dss, which corresponds to the current detection time Tid. During the current detection voltage vector period Q1f, a current detection command 120f is output such that the voltage command vector Vuvw* detects the U-phase rotating machine current Imu. The duration of the current detection voltage vector period Q1f is the adjustment amount Dsf, which corresponds to the current detection time Tid.

[0148] When detecting the U-phase rotating machine current Imu in the carrier period (third current detection period Sd3) immediately after time tc4, the current is detected at, for example, detection timing Tu corresponding to detection timing Tgf in FIG. 29 . At detection timing Tu, the U-phase rotating machine current Imu can be detected immediately after the on-off signal Up2 for the U-phase upper arm transitions from on level to off level. When detecting the W-phase rotating machine current Imw in the carrier period (fourth current detection period Sd4) immediately before time tc6, the current is detected at, for example, detection timing Tw corresponding to detection timing Tgs in FIG. 29 . At detection timing Tw, the W-phase rotating machine current Imw can be detected immediately before the on-off signal Wp2 for the W-phase upper arm transitions from off level to on level. In Figure 29, the on / off signal Up2 before adjustment of the U-phase upper arm is shifted as shown by arrow 54u to generate the on / off signal Up2 so that the U-phase rotating machine current Imu and the W-phase rotating machine current Imw can be detected.

[0149] The detected on / off signal vector 121s shown in FIG. 29 is a non-zero voltage vector 123 in which the on / off signals Up2, Vp2, and Wp2 are "on," "on," and "off," and in which the W-phase rotating machine current Imw can be detected. The current detection command 120s shown in FIG. 29 is a command having command values ​​for each phase in the command waveforms 104u2, 104v, and 104w from time t5 to time t6. The detected on / off signal vector 121f shown in FIG. 29 is a non-zero voltage vector 123 in which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and in which the U-phase rotating machine current Imu can be detected. The current detection command 120f shown in FIG. 29 is a command having command values ​​for each phase in the command waveforms 104u2, 104v, and 104w from time t1 to time t2.

[0150] From the above, as in the fourth example of the operation of the inductance measurement device 1, assuming that the voltage commands Vu*, Vv*, and Vw* are rectangular wave voltages with a 120° phase difference between the phases, the command period Tmc is six times the carrier period Tc, and the voltage amplitudes of the phases are equal, and the starting point of the carrier signal 51 is set to the valley Pv, peaks of the rotating machine current Im of two phases can be detected during a predetermined carrier period Tc, which is a predetermined cycle period. The predetermined carrier period Tc corresponds to the third current detection period Sd3 in one phase and the fourth current detection period Sd4 in the other phase. The carrier period 81e in FIG. 28 corresponds to the third current detection period Sd3 in the U phase and the fourth current detection period Sd4 in the W phase. That is, the carrier period 81e in FIG. 28 corresponds to a predetermined cycle period in which the third current detection period Sd3 and the fourth current detection period Sd4 are simultaneously realized. In the first half of the carrier Trmf of the carrier period 81e, a detection timing Tgf is set for detecting the positive peak of the U-phase rotating machine current Imu, which corresponds to the third current detection period Sd3, and in the second half of the carrier Trms, a detection timing Tgs is set for detecting the negative peak of the W-phase rotating machine current Imw, which corresponds to the fourth current detection period Sd4 and is a phase different from the first half of the carrier Trmf.

[0151] The carrier period 81f in FIG. 28 corresponds to the third current detection period Sd3 in the V-phase and the fourth current detection period Sd4 in the U-phase. That is, the carrier period 81f in FIG. 28 is a predetermined cycle period in which the third current detection period Sd3 and the fourth current detection period Sd4 are simultaneously realized. The detection timing Tgf for detecting the positive peak of the V-phase rotor current Imv corresponding to the third current detection period Sd3 is set in the carrier first half Trmf of the carrier period 81f. The detection timing Tgs for detecting the negative peak of the U-phase rotor current Imu corresponding to the fourth current detection period Sd4, which is a different phase from the carrier first half Trmf, is set in the carrier second half Trms. The carrier period 81d in FIG. 28 corresponds to the third current detection period Sd3 in the W-phase and the fourth current detection period Sd4 in the V-phase. That is, the carrier period 81d in FIG. 28 is a predetermined cycle period in which the third current detection period Sd3 and the fourth current detection period Sd4 are simultaneously realized. In the first half of the carrier Trmf of the carrier period 81d, a detection timing Tgf is set for detecting the positive peak of the W-phase rotor current Imw corresponding to the third current detection period Sd3, and in the second half of the carrier Trms, a detection timing Tgs is set for detecting the negative peak of the V-phase rotor current Imv, which corresponds to the fourth current detection period Sd4 and is a phase different from the first half of the carrier Trmf.

[0152] When the starting point of the carrier signal 51 is set to the peak Pp, the timing determiner 35 generates a detection target phase signal sgp and a detection timing signal sgs including two detection target phases Pid and detection timings Tg for each of the two phases during carrier periods 81a, 81b, and 81c, which are periods of a predetermined carrier cycle Tc, and outputs these to the adjustment amount determiner 36. Specifically, during the carrier period 81a, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the V-phase and a detection timing signal sgs indicating the time of detection timing Tgf for the V-phase, and outputs these to the adjustment amount determiner 36. Furthermore, during the carrier period 81a, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the U-phase and a detection timing signal sgs indicating the time of detection timing Tgs for the U-phase, and outputs these to the adjustment amount determiner 36.

[0153] Similarly, during the carrier period 81b, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the W phase and a detection timing signal sgs indicating the time of detection timing Tgf for the W phase, and outputs these to the adjustment amount determiner 36. Also, during the carrier period 81b, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the V phase and a detection timing signal sgs indicating the time of detection timing Tgs for the V phase, and outputs these to the adjustment amount determiner 36. Similarly, during the carrier period 81c, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the U phase and a detection timing signal sgs indicating the time of detection timing Tgf for the U phase, and outputs these to the adjustment amount determiner 36. In addition, during the carrier period 81c, the timing determination unit 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the W phase, and a detection timing signal sgs indicating the time of the detection timing Tgs of the W phase, and outputs them to the adjustment amount determination unit 36.

[0154] When the starting point of the carrier signal 51 is set to the valley Pv, the timing determiner 35 generates a detection target phase signal sgp and a detection timing signal sgs including detection target phases Pid and detection timings Tg for two phases, respectively, during carrier periods 81d, 81e, and 81f, which are periods of a predetermined carrier cycle Tc, and outputs these to the adjustment amount determiner 36. Specifically, during the carrier period 81d, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the W phase and a detection timing signal sgs indicating the time of detection timing Tgf for the W phase, and outputs these to the adjustment amount determiner 36. Furthermore, during the carrier period 81d, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the V phase and a detection timing signal sgs indicating the time of detection timing Tgs for the V phase, and outputs these to the adjustment amount determiner 36.

[0155] Similarly, during the carrier period 81 e, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the U phase and a detection timing signal sgs indicating the time of detection timing Tgf for the U phase, and outputs these to the adjustment amount determiner 36. Furthermore, during the carrier period 81 e, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the W phase and a detection timing signal sgs indicating the time of detection timing Tgs for the W phase, and outputs these to the adjustment amount determiner 36. Similarly, during the carrier period 81 f, the timing determiner 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the V phase and a detection timing signal sgs indicating the time of detection timing Tgf for the V phase, and outputs these to the adjustment amount determiner 36. In addition, during the carrier period 81f, the timing determination unit 35 generates a detection target phase signal sgp indicating that the detection target phase Pid is the U phase, and a detection timing signal sgs indicating the time of the detection timing Tgs of the U phase, and outputs them to the adjustment amount determination unit 36.

[0156] If the starting point of the carrier signal 51 is set to the peak Pp, the adjustment amount determination unit 36 ​​determines one phase, i.e., the adjustment target phase Dp, that must be shifted in order to detect a value as close as possible to the positive peak of the U-phase rotating machine current Imu at the detection timing Tgs of Figure 27 determined by the timing determination unit 35 during the carrier period 81a, and to detect a value as close as possible to the negative peak of the V-phase rotating machine current Imv at the detection timing Tgf of Figure 27 determined by the timing determination unit 35, and calculates the adjustment amount Ds required for the adjustment target phase Dp.

[0157] The voltage command adjuster 39 outputs an adjustment voltage command sgca adjusted based on one adjustment target phase Dp and one adjustment amount Ds determined by the adjustment amount determiner 36, and the PWM signal generator 33 generates an on-off signal sg2 pulse-shifted based on the adjustment voltage command sgca. That is, the voltage command adjuster 39 and the PWM signal generator 33 perform pulse shift processing of the on-off signal sg2 based on one adjustment target phase Dp and one adjustment amount Ds determined by the adjustment amount determiner 36. In the example of FIG. 27 , the adjustment amount determiner 36 sets the adjustment target phase Dp to the U-phase and the adjustment amount Ds to the current detection time Tid, so the voltage command adjuster 39 generates an adjustment voltage command sgca that shifts the on-off signal Up2 before adjustment of the U-phase backward in time by the current detection time Tid within the cycle period (carrier period 81 a) of the carrier signal 51.

[0158] If the starting point of the carrier signal 51 is set to peak Pp, the phase current output unit 31 outputs the U-phase rotating machine current Imu and the V-phase rotating machine current Imv at the two detection timings Tgf and Tgs determined as described above, thereby making it possible to detect the positive peak of the U-phase rotating machine current Imu and the negative peak of the V-phase rotating machine current Imv with high accuracy.

[0159] 26 is the carrier cycle immediately before the timing of time tc8 and immediately after the timing of time tc6, and carrier period 81c in Fig. 26 is the carrier cycle immediately before the timing of time tc12 and immediately after the timing of time tc10. Therefore, by performing an operation based on the same concept as the operation in carrier period 81a in Fig. 26, the positive peak of the V-phase rotating machine current Imv and the negative peak of the W-phase rotating machine current Imw can be detected with high accuracy in carrier period 81b, and the positive peak of the W-phase rotating machine current Imw and the negative peak of the U-phase rotating machine current Imu can be detected with high accuracy in carrier period 81c.

[0160] If the starting point of the carrier signal 51 is set to the valley Pv, the adjustment amount determination unit 36 ​​determines one phase, i.e., the adjustment target phase Dp, that must be shifted in order to detect a value as close as possible to the negative peak of the W-phase rotating machine current Imw at the detection timing Tgs of Figure 29 determined by the timing determination unit 35 during the carrier period 81e, and to detect a value as close as possible to the positive peak of the U-phase rotating machine current Imu at the detection timing Tgf of Figure 29 determined by the timing determination unit 35, and calculates the adjustment amount Ds required for the adjustment target phase Dp.

[0161] The voltage command adjuster 39 and the PWM signal generator 33 perform pulse shift processing of the on / off signal sg2 based on one adjustment target phase Dp and one adjustment amount Ds determined by the adjustment amount determiner 36. In the example of Fig. 29 , the adjustment amount determiner 36 sets the adjustment target phase Dp to the U phase and the adjustment amount Ds to the current detection time Tid, and therefore the voltage command adjuster 39 generates an adjustment voltage command sgca that shifts the on / off signal Up2 before adjustment of the U phase forward in time within the cycle period of the carrier signal 51 (carrier period 81e) by the current detection time Tid.

[0162] If the starting point of the carrier signal 51 is the valley Pv, the phase current output unit 31 outputs the U-phase rotating machine current Imu and the W-phase rotating machine current Imv at the two detection timings Tgf and Tgs determined as described above, thereby making it possible to detect the positive peak of the U-phase rotating machine current Imu and the negative peak of the W-phase rotating machine current Imw with high accuracy.

[0163] Furthermore, carrier period 81d in Fig. 28 is the carrier period immediately before the timing of time tc2 and immediately after the timing of time tc0c, and carrier period 81f in Fig. 28 is the carrier period immediately before the timing of time tc10 and immediately after the timing of time tc8. Therefore, by performing an operation based on the same concept as the operation in carrier period 81e in Fig. 28, the positive peak of the W-phase rotating machine current Imw and the negative peak of the V-phase rotating machine current Imv can be detected with high accuracy in carrier period 81d, and the positive peak of the V-phase rotating machine current Imv and the negative peak of the U-phase rotating machine current Imu can be detected with high accuracy in carrier period 81f.

[0164] The timing determiner 35 only determines the detection target phase Pid and the detection timings Tgf, Tgs for detecting the positive and negative peaks of the rotating machine current Im of each phase, and may detect the rotating machine current Im of any phase at any detection timing Tg during a period of the carrier cycle Tc that is not specified by the timing determiner 35 as the detection target phase Pid and the detection timings Tgf, Tgs for detecting the positive or negative peaks of the rotating machine current Im of each phase, i.e., during a period of the carrier cycle Tc other than the predetermined carrier cycle Tc. That is, in the example of Fig. 26, for example, during the periods of the carrier cycle Tc before and after the carrier period 81a, the U-phase and V-phase rotating machine currents Im may be detected at any detection timing Tg, or the U-phase and W-phase rotating machine currents Im may be detected at any detection timing Tg.

[0165] Up to this point, we have described in detail an example in which the control unit 4 shifts the pre-adjustment PWM signal when measuring the inductance Lm of the rotating machine 2. However, as previously mentioned, the control unit 4 may also adjust the pulse width of the pre-adjustment PWM signal, i.e., compensate for the voltage command value. FIG. 30 illustrates an example of voltage command value compensation during the first current detection period Sd1. FIG. 30 illustrates an example in which adjustment using voltage command value compensation is performed during the first current detection period Sd1. The same reference numerals used in FIG. 30 are used as in FIG. 19 , which illustrates adjustment using pulse shifting during the first current detection period Sd1. Differences from FIG. 19 will be mainly described. In FIG. 30 , the pulse width of the U-phase on / off signal Up2 is expanded in time backward, i.e., in the direction of arrow 54u, from before adjustment. Therefore, the post-adjustment command waveform 68u2 is the same as the pre-adjustment command waveform 68u1 in the first-half carrier Trmf, and the command value in the second-half carrier Trms is increased by the command value adjustment amount α from before adjustment. Time t2 has been omitted from FIG. 30 to facilitate comparison with FIG. 19 . 30 , the adjusted on / off signal Up2 is at an on level from time t1 to time t6. The carrier second-half Trms in FIG. 30 is the same as the carrier second-half Trms in FIG. 19 . Therefore, even if the control unit 4 performs adjustment using voltage command value compensation, it is possible to generate a current detection command 120 and a detected on / off signal vector 121 near the sign reversal timing Tsr at which the phase current of the detection target phase Pid, ​​at which the sign of the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the inductive load (rotating machine 2) reverses, reaches a peak, just as in adjustment using pulse shift. Therefore, even if the control unit 4 performs adjustment using voltage command value compensation, it is possible to obtain the same effect as adjustment using pulse shift.

[0166] The inductance measurement method of the first embodiment is realized by the operations of the components of the control unit 4, namely, the phase current output unit 31, the voltage command calculation unit 32, the voltage command adjustment unit 39, the timing determination unit 35, the adjustment amount determination unit 36, the PWM signal generation unit 33, the inductance calculation unit 37, and the operation mode switching unit 38. The operation of the phase current output unit 31 constitutes a phase current detection step, the operation of the voltage command calculation unit 32 constitutes a current detection command generation step, and the operation of the voltage command adjustment unit 39 constitutes a voltage command adjustment step. The operation of the timing determination unit 35 constitutes a timing determination step for determining the detection target phase Pid and the current detection timing (detection timing Tg) for detecting the phase current of the detection target phase Pid. The operation of the adjustment amount determination unit 36 ​​constitutes an adjustment amount determination step for determining the adjustment target phase Dp and the adjustment amount Ds. The operation of the PWM signal generation unit 33 constitutes a switching command generation step for generating a switching command, i.e., the on / off signal sg2. The operation of the inductance calculation unit 37 constitutes an inductance calculation step, and the operation of the operation mode switching unit 38 constitutes an operation mode switching step.

[0167] The operation and effect of the first embodiment of the present disclosure will be described. According to the inductance measurement device 1 of the first embodiment of the present disclosure, when measuring the inductance Lm of the rotating machine 2, it is possible to detect the positive peak and the negative peak of the rotating machine current Im of all phases with high accuracy. As a result, the inductance measurement device 1 of the first embodiment can measure the inductance Lm of the rotating machine 2 with high accuracy using the three-phase current Iuvw that is output by detecting or calculating the rotating machine current Im. The inductance measurement device 1 of the first embodiment can increase the amplitude of the high-frequency voltage by increasing the frequency when the high-frequency voltage is applied, thereby further improving the detection accuracy of the current peaks of all phases when using a single-shunt current detection method.

[0168] The control unit 4 of the inductance measurement device 1 of embodiment 1 executes a power conversion unit control step, a phase current detection step, and an inductance calculation step. In the power conversion unit control step, the control unit 4 calculates a voltage command sgc of AC power when a three-phase voltage Vuvw is applied to the rotating machine 2 using a voltage command calculation unit 32, and controls the power conversion unit 3 using an on / off signal sg2 to the switching elements 11a to 11f that is calculated based on the voltage command sgc and a carrier signal 51 and output from a PWM signal generation unit 33. Furthermore, the control unit 4 determines, based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr, using a timing determination unit 35 to detect the phase currents Iu, Iv, and Iw of the detection target phase Pid in the voltage unit interval Tru before the sign reversal timing Tsr or in the voltage unit interval Tru after the sign reversal timing Tsr. In the phase current detecting step, during control of the power conversion unit 3 by the power conversion unit control step, the control unit 4 detects the DC bus current Idc flowing through the DC terminal 13n of the power conversion unit 3 using the current detecting unit 5, and detects the phase currents Iu, Iv, and Iw of the rotating machine 2 using the DC bus current Idc using the phase current output unit 31. In the inductance calculating step, the control unit 4 executes an inductance calculating step to calculate the inductance Lm of the rotating machine 2 based on the detected values ​​of the phase currents Iu, Iv, and Iw and the voltage command sgc. According to the inductance measuring method of the first embodiment of the present disclosure, when measuring the inductance Lm of the rotating machine 2, the positive peak and the negative peak of the rotating machine current Im of all phases can be detected with high accuracy. As a result, the inductance measuring method of the first embodiment can measure the inductance Lm of the rotating machine 2 with high accuracy using the three-phase currents Iuvw output by detecting or calculating the rotating machine current Im.

[0169] Although the inductance measurement device 1 has been described as an example of an inductive load, the inductance of an inductive load is not limited to a rotating machine, and the inductance of an inductive load other than a rotating machine can be measured with high accuracy. Also, although the rotating machine 2 has been described as a three-phase rotating machine, the inductance of the rotating machine 2 is not limited to three phases and can be a multi-phase machine such as six phases, or a single phase, etc., and can be measured with high accuracy by the inductance measurement device 1.

[0170] As described above, the inductance measuring device 1 of the first embodiment is a device that applies an AC voltage (three-phase voltage Vuvw) to an inductive load (rotating machine 2) and measures the inductance Lm of the inductive load (rotating machine 2). The inductance measurement device 1 includes a power conversion unit 3 that receives DC power as input, converts it using a plurality of switching elements 11 a to 11 f, and supplies the converted AC power to an inductive load (rotating machine 2); a current detection unit 5 that detects a current flowing through a DC terminal 13 n of the power conversion unit 3; and a control unit 4 that calculates a voltage command sgc for AC power when an AC voltage (three-phase voltage Vuvw) is applied to the inductive load (rotating machine 2), controls the power conversion unit 3 based on switching commands (on / off signals sg2) to the switching elements 11 a to 11 f calculated based on the voltage command sgc and a carrier signal 51, and detects phase currents Iu, Iv, and Iw of the inductive load (rotating machine 2) based on a DC current (DC bus current Idc) detected by the current detection unit 5 while the power conversion unit 3 is being controlled by the switching command (on / off signal sg2). The inductance measurement device 1 is configured to calculate an inductance Lm of the inductive load (rotating machine 2) based on the detected values ​​of the phase currents Iu, Iv, and Iw and the voltage command sgc. The vertices of the carrier signal 51 that are maximum and minimum values ​​are defined as a first vertex (peak Pp) and a second vertex (valley Pv), respectively, and the section between the adjacent first vertex (peak Pp) and second vertex (valley Pv) is defined as a voltage unit interval Tru. The voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the inductive load (rotating machine 2) is defined as a sign determination target. The timing at the end of the voltage unit interval Tru at which the sign of the target for sign determination is reversed is defined as a sign reversal timing Tsr. The phase of the AC voltage (three-phase voltage Vuvw) whose sign is reversed at the sign reversal timing Tsr is defined as a detection target phase Pid for the phase currents Iu, Iv, and Iw to be detected. The control unit 4 determines, based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr, to detect the phase currents Iu, Iv, and Iw of the detection target phase Pid in the voltage unit interval Tru before the sign reversal timing Tsr or in the voltage unit interval Tru after the sign reversal timing Tsr.With this configuration, the inductance measurement device 1 of embodiment 1 allows the control unit 4 to determine, based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr, to detect the phase currents Iu, Iv, and Iw of the detection target phase Pid in the voltage unit interval Tru before the sign reversal timing Tsr or in the voltage unit interval Tru after the sign reversal timing Tsr. Therefore, when an AC voltage (three-phase voltage Vuvw) is applied to measure the inductance Lm of the inductive load (rotating machine 2), the peak current can be detected with high accuracy.

[0171] The inductance measurement method of the first embodiment is a method for measuring the inductance Lm of the inductive load (rotating machine 2) by applying an AC voltage (three-phase voltage Vuvw) to the inductive load (rotating machine 2) by the power conversion unit 3. The power conversion unit 3 is configured to receive DC power as input, convert the converted AC power by a plurality of switching elements 11a to 11f, and supply the AC power to the inductive load (rotating machine 2). The inductance measurement method of the first embodiment includes a power conversion unit control step of calculating a voltage command sgc of AC power when an AC voltage (three-phase voltage Vuvw) is applied to an inductive load (rotating machine 2), and controlling the power conversion unit 3 based on switching commands (on / off signals sg2) to switching elements 11a to 11f calculated based on the voltage command sgc and a carrier signal 51; a phase current detection step of detecting a DC current (DC bus current Idc) flowing through a DC terminal 13n of the power conversion unit 3 by a current detection unit 5 while the power conversion unit 3 is being controlled by the power conversion unit control step, and detecting phase currents Iu, Iv, and Iw of the inductive load (rotating machine 2) from the DC current (DC bus current Idc); and an inductance calculation step of calculating an inductance Lm of the inductive load (rotating machine 2) based on the detected values ​​of the phase currents Iu, Iv, and Iw and the voltage command sgc. The vertices of the carrier signal 51 that are maximum and minimum values ​​are defined as a first vertex (peak Pp) and a second vertex (valley Pv), respectively, and the section between the adjacent first vertex (peak Pp) and second vertex (valley Pv) is defined as a voltage unit interval Tru. The voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the inductive load (rotating machine 2) is defined as a sign determination target, and the timing at the end of the voltage unit interval Tru at which the sign of the target for sign determination is inverted is defined as a sign reversal timing Tsr. The phase of the AC voltage (three-phase voltage Vuvw) whose sign is inverted at the sign reversal timing Tsr is defined as the detection target phase Pid of the phase currents Iu, Iv, and Iw to be detected. In the power conversion unit control process, based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr, it is determined that the phase currents Iu, Iv, and Iw of the phase Pid to be detected are detected in the voltage unit interval Tru before the sign reversal timing Tsr or in the voltage unit interval Tru after the sign reversal timing Tsr.With this configuration, the inductance measurement method of embodiment 1 determines in the power conversion unit control step based on the change tendency of the carrier signal 51 before and after the sign reversal timing Tsr that the phase currents Iu, Iv, and Iw of the detection target phase Pid will be detected in the voltage unit interval Tru before the sign reversal timing Tsr or in the voltage unit interval Tru after the sign reversal timing Tsr. Therefore, when an AC voltage (three-phase voltage Vuvw) is applied to measure the inductance Lm of the inductive load (rotating machine 2), the peak current can be detected with high accuracy.

[0172] Embodiment 2. Fig. 31 is a diagram showing an example of a voltage command and a phase current of a rotating machine in an inductance measurement device according to embodiment 2. Fig. 32 is a diagram showing a first example of current detection timing in a first carrier period of Fig. 31, and Fig. 33 is a diagram showing an example of current detection timing in a second carrier period of Fig. 31. Fig. 34 is a diagram showing a second example of current detection timing in the first carrier period of Fig. 31. In the inductance measuring device 1 of embodiment 1, the timing determination unit 35 utilizes the fact that the phase difference Δγ between the high-frequency voltage or high-frequency voltage command, which generates a fundamental wave current in the rotating machine 2 using a quasi-fundamental wave voltage including the fundamental wave, and the rotating machine current Im, being 90°, to determine that the peak of the rotating machine current Im of a certain phase (detection target phase Pid) will appear at a timing 90° delayed from the time (timing) at which the peak of the high-frequency voltage or high-frequency voltage command of the certain phase appears, and determines the detection timing Tg for detecting the rotating machine current Im of the detection target phase Pid so that a current value closest to the peak value of the rotating machine current Im of the detection target phase Pid can be detected. In the inductance measuring device 1 of embodiment 2, an example will be described in which the timing determination unit 35 determines the timing at which the peak of the rotating machine current Im of the detection target phase Pid appears even when the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im is other than 90°, and determines the detection timing Tg for detecting the rotating machine current Im of the detection target phase Pid so that the current value closest to the peak value of the rotating machine current Im of the detection target phase Pid can be detected.

[0173] The inductance measurement device 1 of embodiment 2 differs from the inductance measurement device 1 of embodiment 1 in that the timing determination unit 35 outputs a detection target phase signal sgp including information on the detection target phase Pid that can detect a current value closest to the peak value of the rotating machine current Im of the detection target phase Pid, ​​even if the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im is other than 90°. The following mainly describes the parts that differ from the inductance measurement device 1 of embodiment 1. In embodiment 2, the same components as those described in embodiment 1 are assigned the same reference numerals, and detailed description thereof will be omitted.

[0174] The timing determination unit 35 of the second embodiment has a function of estimating a phase shift β, which is the amount of deviation from a reference value of 90°, of the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im. The unit of the phase shift β is degrees (°). The timing determination unit 35 has a phase shift estimating unit that estimates the phase shift β. The timing determination unit 35 estimates the phase shift β based on, for example, electrical constants of the rotating machine 2 calculated from approximate values ​​of the inductance Lm and resistance of the rotating machine 2.

[0175] The inductance Lm of the rotating machine 2, which is required when determining the electrical constants of the rotating machine 2, is often unknown, and therefore may be an approximate value determined by some other method. After calculating an approximate value of the inductance Lm by some other method, the inductance measuring device 1 of the second embodiment can be used to measure the inductance Lm with high accuracy.

[0176] The timing determiner 35 determines the detection target phase Pid for detecting a current and the detection timing Tg for detecting the rotating machine current Im of the detection target phase Pid based on the estimated phase shift β. That is, when the timing determiner 35 estimates that the phase shift β is the amount of deviation of the phase difference Δγ from a reference value, the timing determiner 35 determines that the phase difference Δγ is 90°-β and that the peak of the rotating machine current Im of the detection target phase Pid appears at a timing 90°-β delayed from the peak timing of the "fundamental wave of the high-frequency voltage or high-frequency voltage command" that generates the fundamental wave rotating machine current Im in the rotating machine 2 in a certain phase (detection target phase Pid). The "fundamental wave of the high-frequency voltage or high-frequency voltage command" may also be a "quasi-fundamental wave of the high-frequency voltage or high-frequency voltage command." The timing determiner 35 determines the detection timing Tg of the detection target phase Pid so that a current value closest to the peak value of the rotating machine current Im of the detection target phase Pid can be detected near a timing 90°-β delayed from the determined peak timing. Note that when the phase shift β is greater than 90°, the phase difference Δγ becomes a negative value, so that time tc3 shown in Fig. 31 comes earlier in time than time tc1, and time tc4 shown in Fig. 31 comes earlier in time than time tc2. Even in this case, the inductance measuring device 1 of embodiment 2 can measure the inductance Lm with high accuracy.

[0177] The inductance measuring device 1 of the second embodiment corrects the detection timing Tg in accordance with the phase shift amount β, so that it can detect the positive peak and the negative peak of the rotating machine current Im of all phases with high accuracy even when the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im is not 90°. This will be described in detail below.

[0178] An example of the operation of the inductance measuring device 1 of the second embodiment will be described. Fig. 31 shows an example of a carrier signal 51 whose starting point in the period of the carrier cycle Tc is a peak Pp, voltage commands Vu*, Vv*, and Vw*, and a rotating machine current Im which is a three-phase current of the rotating machine 2. Fig. 31 shows an example in which the phase difference Δγ between the high-frequency voltage command and the rotating machine current Im is other than 90°. The operations of the timing determination unit 35, voltage command adjustment unit 39, PWM signal generation unit 33, adjustment amount determination unit 36, and phase current output unit 31 in the second embodiment will be described in detail. Note that a carrier period 81g and a carrier period 81h are the first carrier period and the second carrier period in Fig. 31, respectively.

[0179] In FIG. 31 , the voltage command calculation unit 32 outputs the components of the voltage command vector Vuvw*, which is a high-frequency voltage command expressed as a vector, i.e., the voltage commands Vu*, Vv*, and Vw*, as rectangular wave voltages with a 120° phase difference between each phase and equal voltage amplitude for each phase. The phase difference between the voltage commands Vu*, Vv*, and Vw* and the rotating machine current is Δγ. Furthermore, the command period Tmc (from a rising edge to the next rising edge or from a falling edge to the next falling edge), which is the period of the voltage commands Vu*, Vv*, and Vw*, is 12 times the carrier period Tc. The waveforms of the voltage commands Vu*, Vv*, and Vw* are command waveforms 102u, 102v, and 102w, respectively. Since the rotating machine current Im has a waveform similar to the phase current waveform 47 in FIG. 17 , the voltage commands having the command waveforms 102u, 102v, and 102w are used as the basic voltage command 119, as in the first embodiment. Therefore, the three-phase voltages supplied to the rotating machine 2 by the command waveforms 102u, 102v, and 102w can be said to be quasi-fundamental waves.

[0180] The rotating machine current Imu, which is the U-phase rotating machine current Im, reaches a positive peak at time tc3 and a negative peak at time tc4. The rotating machine current period Tmi, like the command period Tmc, is 12 times the carrier period Tc, even though there is a phase difference Δγ, as in the first embodiment. Note that, as in the first embodiment, the command period Tmc will be described using an example in which the period ends are the rising edges of the command waveforms 102u, 102v, and 102w. Time tc5 is the falling edge of the U-phase command waveform 102u, and corresponds to the command period midpoint Tmcc, which is the midpoint of the U-phase command period Tmc. Time tc5 is the timing when the sign of the command value of the base voltage command 119 changes from positive to negative, thereby becoming the first special phase 125. Time tc6 is the timing when the sign of the command value of the base voltage command 119 changes from negative to positive, thereby becoming the second special phase 126.

[0181] Time tc1 in FIG. 31 is the intermediate time of the positive command value period of the voltage command Vu*. Time tc2 in FIG. 31 is the intermediate time of the negative command value period of the voltage command Vu*. The period from time tc1 to time tc5 in FIG. 31 is the command phase difference Δθ in one phase of the voltage command sgc, and the command phase difference Δθ is 90°. The period from time tc2 to time tc6 in FIG. 31 is the command phase difference Δθ in one phase of the voltage command sgc, and the command phase difference Δθ is 90°. The phase difference Δγ is from time tc1, which is the intermediate time of the positive command value period of the U-phase voltage command Vu*, to time tc3, when the U-phase rotating machine current Imu reaches its positive peak. The phase difference Δγ is from time tc2, which is the intermediate time of the negative command value period of the U-phase voltage command Vu*, to time tc4, when the U-phase rotating machine current Imu reaches its negative peak. Furthermore, the command phase difference from time tc3 to time tc5 is β, and the command phase difference from time tc4 to time tc6 is β. If the phase shift amount β estimated by the timing determination unit 35 is used, the phase difference Δγ becomes 90°−β.

[0182] For ease of explanation, peaks Pp of the carrier signal 51 are numbered from time tc2 onward. Peaks Pp1, Pp2, Pp3, Pp4, Pp7, Pp8, Pp9, and Pp10 are shown in FIG. Peaks Pp1, Pp4, Pp7, and Pp10 appear at times tc1, tc5, tc2, and tc6, respectively. Time tc3, when the positive peak of the U-phase rotating machine current Imu appears, is included in a carrier period 81g whose cycle ends are peaks Pp2 and Pp3. Time tc4, when the negative peak of the U-phase rotating machine current Imu appears, is included in a carrier period 81h whose cycle ends are peaks Pp8 and Pp9.

[0183] When the timing determination unit 35 estimates that the value of the phase shift amount β, which is the deviation from a reference value in the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im, is β, it determines that the phase difference Δγ is 90°-β.

[0184] The positive peak of the U-phase rotating machine current Imu appears at time tc3, which is shifted by a phase difference Δγ from time tc1, which is the middle time of a positive command value period in the command waveform 102u when the voltage command Vu* is a square wave. The negative peak of the U-phase rotating machine current Imu appears at time tc4, which is shifted by a phase difference Δγ from time tc2, which is the middle time of a negative command value period in the command waveform 102u when the voltage command Vu* is a square wave. The timing determination unit 35 determines that the positive peak of the U-phase rotating machine current Imu appears at time tc3, which is delayed by 90°-β from time tc1, i.e., by the phase difference Δγ, and that the negative peak of the U-phase rotating machine current Imu appears at time tc4, which is delayed by 90°-β from time tc2, i.e., by the phase difference Δγ. In order to detect the current closest to the positive and negative peaks of the U-phase rotating machine current Imu that appear at times tc3 and tc4, the timing determination unit 35 determines one of the phases for detecting current in carrier period 81g to be the U-phase, and determines one of the phases for detecting current in carrier period 81h to be the U-phase.

[0185] At this time, the timing determination unit 35 determines whether it is possible to detect the U-phase rotating machine current Imu at times tc3 and tc4. If it is determined that it is possible to detect the U-phase current at times tc3 and tc4, the timing determination unit 35 sets the U-phase detection timing Tu in the carrier period 81g to time tc3, and sets the U-phase detection timing Tu in the carrier period 81h to time tc4. If it is determined that it is not possible to detect the U-phase rotating machine current Imu at time tc3, the timing determination unit 35 sets the timing closest to time tc3 as the U-phase detection timing Tu in the carrier period 81g, among candidate timings at which the current can be detected. Similarly, if it is determined that it is not possible to detect the U-phase rotating machine current Imu at time tc4, the timing determination unit 35 sets the timing closest to time tc4 as the U-phase detection timing Tu in the carrier period 81h, among candidate timings at which the current can be detected. It should be noted that times tc3 and tc4 are initial consideration times.

[0186] FIG. 32 is an enlarged view of the carrier period 81g in FIG. 31. In the example of FIG. 32, the timing determination unit 35 determines that it is impossible to detect the U-phase rotating machine current Imu at the initial consideration time, tc3. FIG. 33 is an enlarged view of the carrier period 81h in FIG. 31. In the example of FIG. 33, the timing determination unit 35 determines that it is possible to detect the U-phase rotating machine current Imu at the initial consideration time, tc4. FIGS. 32 and 33 are explanatory diagrams of peak-start type signals. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. FIG. 32 depicts the carrier period Tc of the carrier period 81g from time tpp2 to time tpp3, with peak Pp2 at the left cycle end and peak Pp3 at the right cycle end. There is a valley Pv at time tpv, the period from time tpp2 to time tpv is the first half of the carrier Trmf, and the period from time tpv to time tpp3 is the second half of the carrier Trms. Figure 33 shows the carrier period Tc of carrier period 81h from time tpp8 to time tpp9, with a peak Pp8 at the left end of the cycle and a peak Pp9 at the right end of the cycle. There is a valley Pv at time tpv, the period from time tpp8 to time tpv is the first half of the carrier Trmf, and the period from time tpv to time tpp9 is the second half of the carrier Trms.

[0187] In Figure 32, the U-phase voltage command Vu* has a command waveform 84u1 before the shift and a command waveform 84u2 after the shift. The V-phase voltage command Vv* has a command waveform 84v1 before the shift and a command waveform 84v2 after the shift. The W-phase voltage command Vw* without shift processing is a command waveform 84w. The U-phase on-off signal Up2 after the shift is an on-on signal waveform 85u, and the V-phase on-off signal Vp2 after the shift is an on-on signal waveform 85v. The W-phase on-off signal Wp2 without shift processing is an on-on signal waveform 85w. In the command waveform 84u2, the command value at the first half of the carrier Trmf is decreased by the command value adjustment amount α1 from before the shift, and the command value at the second half of the carrier Trms is increased by the command value adjustment amount α1 from before the shift. In the command waveform 84v2, the command value at the first half of the carrier Trmf is decreased by the command value adjustment amount α2 from before the shift, and the command value at the second half of the carrier Trms is increased by the command value adjustment amount α2 from before the shift. After the shift, the U-phase on / off signal Up2 is at the on level from time t2 to time t6. The V-phase on / off signal Vp2 is at the on level from time t3 to time tpp3, and the W-phase on / off signal Wp2 is at the on level from time t4 to time t5.

[0188] The period from time t4 to time t5 is a zero voltage vector period Z1 in which the on-off signals Up2, Vp2, and Wp2 are "on," "on," and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time tpp2 to time t2 is a zero voltage vector period Z2 in which the on-off signals Up2, Vp2, and Wp2 are "off," "off," and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t2 to time t3 is a non-zero voltage vector period in which the on-off signals Up2, Vp2, and Wp2 are "on," "off," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detected voltage vector period Q1 in which the detected on-off signal vector 121 is output.

[0189] In FIG. 33 , the U-phase voltage command Vu* is a command waveform 86u1 before the shift and a command waveform 86u2 after the shift. The V-phase voltage command Vv* is a command waveform 86v1 before the shift and a command waveform 86v2 after the shift. The W-phase voltage command Vw* without shift processing is a command waveform 86w. The U-phase on-off signal Up2 after the shift is an on-on signal waveform 87u, and the V-phase on-off signal Vp2 after the shift is an on-on signal waveform 87v. The W-phase on-off signal Wp2 without shift processing is an on-on signal waveform 87w. In the command waveform 86u2, the command value is increased compared to before the shift at the first half of the carrier Trms, and the command value is decreased compared to before the shift at the second half of the carrier Trms. In the command waveform 86v2, the command value is increased only compared to before the shift at the first half of the carrier Trms, and the command value is decreased compared to before the shift at the second half of the carrier Trms. The U-phase on / off signal Up2 after the shift is at the on level from time tc4 to time t5, the V-phase on / off signal Vp2 is at the on level from time t2 to time t4, and the W-phase on / off signal Wp2 is at the on level from time t1 to time t6.

[0190] The period from time tc4 to time t4 is a zero voltage vector period Z1 in which the on-off signals Up2, Vp2, and Wp2 are "on", "on", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time tpp8 to time t1 is a zero voltage vector period Z2f in which the on-off signals Up2, Vp2, and Wp2 are "off", "off", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t6 to time tpp9 is a zero voltage vector period Z2s in which the on-off signals Up2, Vp2, and Wp2 are "off", "off", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t2 to time tc4 is a non-zero voltage vector period in which the on / off signals Up2, Vp2, and Wp2 are "off," "on," and "on," and the set of elements of the on / off signal sg2 becomes a non-zero voltage vector 123, and is also a current detection voltage vector period Q1 in which the detection on / off signal vector 121 is output.

[0191] If it is determined that detection is not possible at the initial consideration time tc3, the timing determination unit 35 selects the detection timing Tu at time t3 as the timing closest to time tc3 among candidate timings at which current detection is possible. Therefore, the timing determination unit 35 sets the detection timing Tu of the U-phase in the carrier period 81g to the timing of time t3.

[0192] The timing determination unit 35 determines that it is possible to detect the U-phase rotating machine current Imu at the timing of time tc4, which is the initial consideration time, and sets the detection timing Tu of the U-phase in the carrier period 81h to the timing of time tc4.

[0193] The adjustment amount determiner 36 determines the phase to be adjusted Dp, i.e., the phase to be adjusted, during the carrier period 81g in order to detect the U-phase rotating machine current Imu at the detection timing Tu in Fig. 32 determined by the timing determiner 35, and calculates the adjustment amount Ds required for the adjustment target phase Dp. The voltage command adjuster 39 outputs an adjustment voltage command sgca adjusted based on the adjustment target phase Dp and the adjustment amount Ds determined by the adjustment amount determiner 36, and the PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 32, taking into account the detectable period 53c that is equal to or longer than the current detection time Tid of the current, the adjustment amount determiner 36 sets the phases to be adjusted Dp to the U phase and the V phase, sets the adjustment amount Dsu of the U phase to x1, and sets the adjustment amount Dsv of the V phase to y1. Therefore, the PWM signal generator 33 generates a U-phase on / off signal Up2 by shifting the pre-adjustment U-phase on / off signal Up2 backward in time by x1 as indicated by arrow 54u within the cycle period of the carrier signal 51 (carrier period 81g), and generates a V-phase on / off signal Vp2 by shifting the pre-adjustment V-phase on / off signal Vp2 backward in time by y1 as indicated by arrow 54v within the cycle period of the carrier signal 51 (carrier period 81g).

[0194] Similarly, adjustment amount determiner 36 determines the phase to be adjusted Dp, i.e., the phase to be adjusted, in order to detect the U-phase rotating machine current Imu at the detection timing Tu in Fig. 33 determined by timing determiner 35 during carrier period 81h, and calculates the adjustment amount Ds required for the adjustment target phase Dp. Voltage command adjuster 39 outputs an adjustment voltage command sgca adjusted based on the adjustment target phase Dp and adjustment amount Ds determined by adjustment amount determiner 36, and PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of Figure 33, taking into account the detectable period 53d that is equal to or longer than the current detection time Tid, the adjustment amount determiner 36 sets the phases to be adjusted Dp to the U-phase and the V-phase, sets the adjustment amount Dsu for the U-phase to x2, and sets the adjustment amount Dsv for the V-phase to y2. Therefore, the PWM signal generator 33 generates a U-phase on / off signal Up2 by shifting the pre-adjustment U-phase on / off signal Up2 forward in time by x2 as indicated by arrow 54u within the cycle period of the carrier signal 51 (carrier period 81h), and generates a V-phase on / off signal Vp2 by shifting the pre-adjustment V-phase on / off signal Vp2 forward in time by y2 as indicated by arrow 54v within the cycle period of the carrier signal 51 (carrier period 81h).

[0195] At the detection timing Tu determined as described above, the phase current output unit 31 outputs the U-phase phase current Iu, thereby enabling the positive and negative peaks of the U-phase rotating machine current Imu to be detected with high accuracy.

[0196] In addition, for the V-phase and W-phase, the detection timing Tg is determined based on the same concept as for the U-phase, and the phase current output unit 31 outputs the phase current Iv of the V-phase and the phase current Iw of the W-phase at this detection timing Tg, thereby making it possible to detect the positive peak and negative peak of the rotating machine current Imv of the V-phase and the rotating machine current Imw of the W-phase with high accuracy.

[0197] The timing determiner 35 only needs to determine the detection target phase Pid and the detection timing Tg for detecting the positive peak and the negative peak of the rotating machine current Im of each phase, and the rotating machine current Im of any phase may be detected at any timing during a period of the carrier cycle Tc that the timing determiner 35 has not specified as the detection target phase Pid and the detection timing Tg for detecting the positive peak or the negative peak of the rotating machine current Im of each phase. That is, in the example of Fig. 31 , for example, during the period of the carrier cycle Tc immediately before the carrier period 81g, the U-phase rotating machine current Imu and the V-phase rotating machine current Imv may be detected at any timing, or the U-phase rotating machine current Imu and the W-phase rotating machine current Imw may be detected at any timing.

[0198] Up to this point, we have described in detail an example in which the control unit 4 shifts the pre-adjustment PWM signal when measuring the inductance Lm of the rotating machine 2. However, as in the first embodiment, the control unit 4 may also adjust the pulse width of the pre-adjustment PWM signal, i.e., compensate for the voltage command value. FIG. 34 shows an example of voltage command value compensation in the carrier period 81g similar to FIG. 32 . FIG. 34 illustrates an example in which adjustment is performed using voltage command value compensation in the carrier period 81g. The same reference numerals used in FIG. 34 are the same as those used in FIG. 32 , which illustrates adjustment using pulse shifting in the carrier period 81g. Differences from FIG. 32 will be mainly described. In FIG. 34 , the pulse end of the U-phase on-off signal Up2 is shifted backward in time from before adjustment, i.e., in the direction of arrow 54u, during the first half of the carrier Trmf, thereby narrowing the pulse width of the U-phase on-off signal Up2. Furthermore, the pulse end of the V-phase on-off signal Vp2 is shifted backward in time from before adjustment, i.e., in the direction of arrow 54v, during the first half of the carrier Trmf, thereby narrowing the pulse width of the V-phase on-off signal Vp2. Therefore, the adjusted command waveform 84u2 has a command value that is reduced by command value adjustment amount α1 from before the shift at the first half of the carrier Trmf, and is the same as the pre-adjustment command waveform 84u1 at the second half of the carrier Trms. The adjusted command waveform 84v2 has a command value that is reduced by command value adjustment amount α2 from before the shift at the first half of the carrier Trms, and is the same as the pre-adjustment command waveform 84v1 at the second half of the carrier Trms. In FIG. 34, time t6 occurs earlier in time than in FIG. 32. In FIG. 34, the adjusted on / off signal Up2 is at the on level from time t2 to time t6. 34 is the same as the first half carrier Trmf in Fig. 32 , so even if the control unit 4 performs adjustment using voltage command value compensation, as with adjustment using pulse shift, it is possible to estimate that the deviation of the phase difference Δγ from the reference value is the phase deviation β, and generate a current detection command 120 and a detected on / off signal vector 121 near the sign reversal timing Tsr-β at which the phase current of the detection target phase Pid, ​​at which the sign of the voltage command sgc or the AC voltage (three-phase voltage Vuvw) applied to the inductive load (rotating machine 2) reverses, reaches a peak. Therefore, even if the control unit 4 performs adjustment using voltage command value compensation, the same effect as adjustment using pulse shift can be obtained.

[0199] The operation and effect of the second embodiment of the present disclosure will be described. According to the inductance measurement device 1 of the second embodiment of the present disclosure, even when the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im is other than 90°, the positive and negative peaks of the rotating machine current Im of all phases can be detected with high accuracy. As a result, the inductance Lm of the rotating machine 2 can be measured with high accuracy using the three-phase current Iuvw output by detecting or calculating the rotating machine current Im. Furthermore, according to the inductance measurement method of the second embodiment of the present disclosure, even when the phase difference Δγ between the high-frequency voltage or high-frequency voltage command and the rotating machine current Im is other than 90°, the positive and negative peaks of the rotating machine current Im of all phases can be detected with high accuracy. As a result, the inductance measurement method of the second embodiment can be used to measure the inductance Lm of the rotating machine 2 with high accuracy using the three-phase current Iuvw output by detecting or calculating the rotating machine current Im.

[0200] Embodiment 3. Figure 35 is a diagram showing an example of a voltage command and a phase current of a rotating machine in an inductance measurement device according to embodiment 3, and Figure 36 is a diagram showing an example of current detection timing in the third carrier period of Figure 35. With the inductance measurement device 1 of embodiment 1, examples have been described in which a positive or negative peak of the rotating machine current Im of a certain phase is detected during one carrier period Tc (first and second examples of operation), and examples have been described in which a positive or negative peak of the rotating machine current Im of a certain phase during a predetermined period is detected and a peak of the opposite polarity to that of the rotating machine current Im of another phase is detected (third and fourth examples of operation). In the third embodiment, an example will be described in which the rotating machine current Im of two phases (first phase, second phase) is detected during one carrier period Tc, and the rotating machine current Im of the remaining phase (third phase) is calculated from the detected rotating machine current Im of the two phases (first phase, second phase) using Kirchhoff's law, thereby calculating the positive peak of the rotating machine current Im of the remaining phase (third phase) with high accuracy.

[0201] The inductance measurement device 1 of embodiment 3 differs from the inductance measurement device 1 of embodiment 1 in that it detects the rotating machine current Im of two phases (first phase, second phase) and calculates the current value near the positive peak of the rotating machine current Im of the remaining phase (third phase) using Kirchhoff's law from the detected rotating machine current Im of the two phases (first phase, second phase) and the equivalent circuit of the rotating machine 2. The following mainly describes the parts that differ from the inductance measurement device 1 of embodiment 1. In embodiment 3, the same components as those described in embodiments 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0202] The timing determiner 35 of the third embodiment operates differently from the timing determiner 35 of the first embodiment. The timing determiner 35 of the third embodiment initially determines a detection target phase Pid1 for detecting a negative peak in the rotating machine current Im of one phase (first phase) and a detection timing Tg1 for detecting the detection target phase Pid1 as the detection target phase Pid and the detection timing Tg. Thereafter, when it is determined that the rotating machine current Im of a second phase different from the first phase is detectable, the timing determiner 35 determines a detection target phase Pid2 for detecting the rotating machine current Im of the second phase and a detection timing Tg2 for detecting the detection target phase Pid2 as another detection target phase Pid and another detection timing Tg. FIG. 35 is the same as FIG. 26 and illustrates an example of a carrier signal 51 whose starting point in the period of the carrier period Tc is a peak Pp, voltage commands Vu*, Vv*, and Vw*, and the rotating machine current Im which is the phase current of three phases of the rotating machine 2. 36 shows an example of carrier signal 51, whose starting point in the period of carrier cycle Tc is peak Pp, voltage commands Vu*, Vv*, Vw*, and on / off signals Up2, Vp2, Wp2 output to power conversion unit 3. Carrier period 81a, carrier period 81b, and carrier period 81c are the first carrier period, second carrier period, and third carrier period in FIG. 35, respectively. Using FIGS. 35 and 36, the operation when the starting point of carrier signal 51 is peak Pp, i.e., when the cycle end of carrier signal 51 is peak Pp, will be described.

[0203] The timing determiner 35 utilizes the fact that the phase difference between the high-frequency voltage or high-frequency voltage command that generates the fundamental wave rotating machine current Im in the rotating machine 2 and the rotating machine current Im is 90° to determine that the negative peak of the target phase rotating machine current Im appears at a timing 90° delayed from the time (timing) when the negative peak of the fundamental wave high-frequency voltage or high-frequency voltage command in a certain phase (the target phase, i.e., the first phase Pid1 to be detected) or the midpoint of the negative voltage value period of the square wave high-frequency voltage or high-frequency voltage command appears, and determines the detection timing Tg1 for detecting the target phase rotating machine current Im so as to detect a current value as close as possible to the negative peak of the target phase rotating machine current Im. Note that the midpoint of the negative voltage value period of the high-frequency voltage command is the midpoint of the negative command value period. The midpoint of the negative voltage value period of the high-frequency voltage is the midpoint of the period during which the square wave high-frequency voltage has a negative voltage value. In other embodiments, when considering the timing at which the peak current of the rotating machine current Im appears based on the rectangular wave high frequency voltage, it is sufficient to consider the phase difference between the peak current of the rotating machine current Im and the midpoint of the negative voltage value period or the midpoint of the positive voltage value period of the rectangular wave high frequency voltage. The midpoint of the positive voltage value period of the high frequency voltage is the midpoint of the period in which the voltage value of the rectangular wave high frequency voltage is positive.

[0204] When the cycle end of the carrier signal 51 becomes a peak Pp, during the period of the carrier cycle Tc (carrier periods 81a, 81b, 81c) for detecting the negative peak of the rotating machine current Im of each phase, the adjustment amount determination unit 36 ​​determines the phase to be adjusted, i.e., the adjustment target phase Dp, for which adjustment processing by shifting or the like is required to detect the rotating machine current Im of the phase for which the negative peak is to be detected, at the detection timing Tg1 for detecting the negative peak in the rotating machine current Im of each phase determined by the timing determination unit 35, and calculates the adjustment amount Ds required for the adjustment target phase Dp.

[0205] An example of the operation of the inductance measurement device 1 of the third embodiment will be described using Figures 35 and 36. The operations of the timing determination unit 35, voltage command adjustment unit 39, PWM signal generation unit 33, adjustment amount determination unit 36, and phase current output unit 31 in the third embodiment will be described in detail. In Figures 35 and 36, the voltage command calculation unit 32 outputs the components of the voltage command vector Vuvw*, which is a high-frequency voltage command expressed as a vector, i.e., the voltage commands Vu*, Vv*, and Vw*, as rectangular wave voltages with a phase difference of 120° between the phases and equal voltage amplitudes for each phase. Furthermore, the command period Tmc, which is the period of the voltage commands Vu*, Vv*, and Vw*, is six times the carrier period Tc. The rotating machine current period Tmi is also six times the carrier period Tc, just like the command period Tmc.

[0206] Time tc4 in Figure 35 is the command cycle middle point Tmcc, which is the middle of the command cycle Tmc for the U-phase. As described above, in the first special phase 125, the sign of the command value of the basic voltage command 119 changes from positive to negative, so time tc4 in Figure 35 is the time at which the U-phase is determined to be the first special phase 125. In the second special phase 126, the sign of the command value of the basic voltage command 119 changes from negative to positive, so time tc10 in Figures 35 and 36 is the time at which the U-phase is determined to be the second special phase 126. The carrier period 81c, which is the period from time tc10 to time tc12, is the period of the carrier cycle Tc that begins at time tc10 when the sign of the command value of the U-phase voltage command Vu* changes from negative to positive in the peak-start type, and is therefore the second current detection period Sd2. Similarly, carrier period 81a, which is the period from time tc2 to time tc4, is a period of the carrier cycle Tc starting at time tc2 when the sign of the command value of the V-phase voltage command Vv* in the peak-start type changes from negative to positive, and is therefore the second current detection period Sd2. Carrier period 81b, which is the period from time tc6 to time tc8, is a period of the carrier cycle Tc starting at time tc6 when the sign of the command value of the W-phase voltage command Vw* in the peak-start type changes from negative to positive, and is therefore the second current detection period Sd2.

[0207] As described above, the voltage commands Vu*, Vv*, and Vw* having command waveforms 80u, 80v, and 80w are three-phase voltage commands sgc in which the three-phase voltages supplied to the rotating machine 2 are quasi-fundamental waves, i.e., the fundamental voltage command 119. The fundamental voltage command 119 generates a fundamental wave rotating machine current Im in the rotating machine 2. When the voltage command Vu* is the fundamental wave, the positive peak of the command value appears at time tc1, and the negative peak of the command value appears at time tc7. In the command waveform 80u of the voltage command Vu*, which is a rectangular wave, time tc1 is the middle time of the positive command value period, and time tc7 is the middle time of the negative command value period. During the command period Tmc, the positive command value period of the voltage command Vu* is the period from time tc0a to time tc4, and the negative command value period of the voltage command Vu* is the period from time tc4 to time tc10.

[0208] The negative peak of the voltage command Vu*, which is the quasi-fundamental wave, or the intermediate time of the negative command value period, appears at time tc7. The timing determination unit 35 determines that the negative peak of the U-phase rotating machine current Imu appears at time tc10, which is 90° delayed from time tc7. In order to detect a value as close as possible to the negative peak of the U-phase rotating machine current Imu that appears at time tc10, the timing determination unit 35 determines that one of the phases for detecting current, i.e., the detection target phase Pid1, is the U-phase during the carrier period Tc immediately after time tc10, i.e., during the carrier period 81c immediately after time tc10. The timing determination unit 35 sets the detection timing Tu as the detection timing Tg1 so that a value as close as possible to the negative peak of the U-phase rotating machine current Imu can be detected during the carrier period 81c immediately after time tc10.

[0209] Fig. 36 is an enlarged view of a period of the carrier cycle Tc immediately after time tc10 in Fig. 35, i.e., a carrier period 81c. The detection timing Tu of the U-phase rotating machine current Imu in the carrier period 81c is, for example, the timing of time t2 in Fig. 36.

[0210] FIG. 36 is an explanatory diagram of a peak-start type signal. The horizontal axis represents time, the vertical axis of the input waveform display represents voltage, and the vertical axis of the output waveform display represents digital signal level. In FIG. 36, the U-phase voltage command Vu* is represented by command waveform 88u1 before shifting and by command waveform 88u2 after shifting. The V-phase voltage command Vv* without shifting is represented by command waveform 88v. The W-phase voltage command Vw* without shifting is represented by command waveform 88w. The U-phase on-off signal Up2 after shifting is represented by on-on signal waveform 89u. The V-phase on-off signal Vp2 without shifting is represented by on-on signal waveform 89v. The W-phase on-off signal Wp2 without shifting is represented by on-on signal waveform 89w. In command waveform 88u2, the command value increases from before shifting in the first half of the carrier Trmf and decreases from before shifting in the second half of the carrier Trms. The U-phase on / off signal Up2 after the shift is at the on level from time t1 to time t6, the V-phase on / off signal Vp2 is at the on level from time t4 to time t5, and the W-phase on / off signal Wp2 is at the on level from time t2 to time t7.

[0211] The period from time t4 to time t5 is a zero voltage vector period Z1 in which the on-off signals Up2, Vp2, and Wp2 are "on", "on", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time tc10 to time t1 is a zero voltage vector period Z2f in which the on-off signals Up2, Vp2, and Wp2 are "off", "off", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t7 to time tc12 is a zero voltage vector period Z2s in which the on-off signals Up2, Vp2, and Wp2 are "off", "off", and the set of elements of the on-off signal sg2 becomes the zero voltage vector 122. The period from time t1 to time t2 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "on," "off," and "off," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q1 during which the detected on-off signal vector 121 for the U-phase (detection target phase Pid1) is output. During this current detection voltage vector period Q1, the detected on-off signal vector 121 for detecting the U-phase rotating machine current Imu is output. The period from time t2 to time t4 is a non-zero voltage vector period during which the on-off signals Up2, Vp2, and Wp2 are "on," "off," and "on," and the set of elements of the on-off signal sg2 becomes the non-zero voltage vector 123, and is also a current detection voltage vector period Q2 during which the detected on-off signal vector 121 for the V-phase (detection target phase Pid2) is output. During this current detection voltage vector period Q2, a detection on / off signal vector 121 for detecting the V-phase rotating machine current Imv is output.

[0212] The adjustment amount determiner 36 determines the phase Dp to be adjusted, that is, the phase that must be shifted in the carrier period 81c in order to detect a value as close as possible to the negative peak of the U-phase rotating machine current Imu at the detection timing Tg1 in Fig. 36 determined by the timing determiner 35, and calculates the adjustment amount Ds required for the adjustment phase Dp. In the example of Fig. 36, the adjustment phase Dp is the U-phase, and the adjustment amount Ds, that is, the adjustment amount Dsu, is the current detection time Tid.

[0213] The voltage command adjuster 39 outputs an adjustment voltage command sgca adjusted based on one adjustment target phase Dp and one adjustment amount Ds determined by the adjustment amount determiner 36, and the PWM signal generator 33 generates a pulse-shifted on / off signal sg2 based on the adjustment voltage command sgca. In the example of FIG. 36 , the adjustment amount determiner 36 determines the adjustment target phase Dp as the U-phase and the adjustment amount Ds as the current detection time Tid. Therefore, the PWM signal generator 33 generates a U-phase on / off signal Up2 by shifting the unadjusted U-phase on / off signal Up2 forward in time as indicated by arrow 54u within the cycle period (carrier period 81c) of the carrier signal 51 by the current detection time Tid. The reason for shifting forward in time as indicated by arrow 54u is to enable detection of the rotating machine current Im of the first-phase detection target phase Pid1 and the second-phase detection target phase Pid2 during the carrier first half Trmf of the carrier period 81c.

[0214] 49 , the timing determination unit 35 receives the adjustment target phase Dp and adjustment amount Ds determined by the adjustment amount determination unit 36, and when a determination condition described later is not satisfied, outputs a reset signal sgnt to the adjustment amount determination unit 36. The timing determination unit 35 determines whether the rotating machine current Im of a second phase different from the detection target phase Pid1, i.e., the detection target phase Pid2, can be detected when the voltage command adjustment unit 39 and the PWM signal generation unit 33 perform a pulse shift of the on / off signal sg2 based on the adjustment target phase Dp and adjustment amount Ds determined by the adjustment amount determination unit 36. Whenever the second-phase rotating machine current Im can be detected, the timing determination unit 35 determines the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, and outputs to the phase current output unit 31 a detection timing signal sgs including information on the detection timing Tg1 and the detection timing Tg2, and a detection target phase signal sgp including information on the detection target phase Pid1 and the detection target phase Pid2.

[0215] If the second-phase rotating machine current Im can be detected, the current values ​​of the rotating machine current Im of two phases, i.e., the first and second phases, are known, and therefore the current value of the remaining phase, i.e., the third phase, can be calculated using Kirchhoff's law from the rotating machine currents Im of the first and second phases and the equivalent circuit of the rotating machine 2. The calculation of the current value of the third phase rotating machine current Im is performed by the phase current output unit 31. Next, the principle of detecting the aforementioned two-phase rotating machine current Im and calculating the current value near the positive peak of the remaining phase, i.e., the third phase, from the detected two-phase rotating machine current Im using Kirchhoff's law will be described.

[0216] 26 and 27 , it has been described that peaks of the rotating machine current Im of two phases can be detected during a period of the carrier cycle Tc, i.e., a predetermined period, which is the first current detection period Sd1 in one phase and the second current detection period Sd2 in the other phase. This predetermined period of the carrier cycle Tc, i.e., the predetermined period, is carrier periods 81 a, 81 b, and 81 c. During carrier periods 81 a, 81 b, and 81 c, which are the period of the predetermined carrier cycle Tc, a negative peak in the rotating machine current Im of one phase can be detected on the side of the peak Pp at the starting end of the carrier cycle Tc, and a positive peak in the rotating machine current Im of the other phase can be detected on the side of the peak Pp at the ending end of the carrier cycle Tc. In the carrier period 81c shown in Figure 36, a negative peak of the U-phase (first phase) rotor current Imu can be detected near the crest Pp at the start of the carrier cycle Tc, i.e., near time tc10, and a positive peak of the W-phase (third phase) rotor current Imw can be detected near the crest Pp at the end of the carrier cycle Tc, i.e., near time tc12. If the V-phase (second phase) rotor current Imv can be detected during the carrier period 81c, which is the duration of the predetermined carrier cycle Tc, a current value near the positive peak of the W-phase rotor current Imw, i.e., a current value as close as possible to the positive peak, can be calculated using Kirchhoff's law. It will be described later that the current value calculated using Kirchhoff's law is a current value as close as possible to the positive peak of the third-phase rotor current Im.

[0217] During a carrier period 81c, which is a period of a predetermined carrier period Tc when the cycle end of the carrier signal 51 becomes a peak Pp, the first phase of the rotating machine current Im, i.e., the detection target phase Pid1, for detecting a current value near the negative peak, is the U phase, and the second phase of the rotating machine current Im, i.e., the detection target phase Pid2, for detecting the rotating machine current Im, is the V phase. The rotating machine current Imu of the first phase, U phase, is detected at a value as close as possible to the negative peak, and the rotating machine current Imv of the second phase, V phase, is detected at a current value when the command value of the voltage command Vv* is minimum. The command value of the V-phase voltage command Vv* is smaller than the command value of the U-phase voltage command Vu* and the command value of the W-phase voltage command Vw*, and the command value of the V-phase voltage command Vv* is minimum during this carrier period 81c. The V-phase is the phase in which the command value of the voltage command Vv* is minimum, i.e., the minimum voltage phase.

[0218] By setting the detection timing Tg2 for detecting the rotating machine current Im of the second phase and the minimum voltage phase and detecting the rotating machine current Im of the minimum voltage phase, it is possible to detect a current close to the average value of the rotating machine current Im of the minimum voltage phase at the start (time tc10) of the carrier period 81c and the minimum voltage phase at the end (time tc12) of the carrier period 81c as the rotating machine current Im of the minimum voltage phase. As a result, the current of the remaining third phase, which is calculated according to Kirchhoff's law from the detected current value of the first phase at which the negative peak of the rotating machine current Im was detected and the detected current value of the second phase and the minimum voltage phase, becomes close to the current at the end (time tc12) of the carrier period 81c. Furthermore, in the third embodiment, the voltage commands Vu*, Vv*, and Vw* are three-phase components of the fundamental voltage command 119, which is a quasi-fundamental wave, the phase difference between the phases of the voltage commands Vu*, Vv*, and Vw* is 120°, the command period Tmc is six times the carrier period Tc, and the phases are rectangular wave voltages with equal voltage amplitudes. Therefore, the value of the third-phase rotating machine current Im calculated using Kirchhoff's law corresponds to the positive peak current value at the end of the carrier period 81c (time tc12) (see FIG. 35 ). Therefore, the third-phase rotating machine current Im calculated by the phase current output unit 31 using Kirchhoff's law is close to the positive peak value of the third-phase rotating machine current Im.

[0219] On the other hand, in the first embodiment, when the cycle end of the carrier signal 51 is the valley Pv, a fourth example of the operation of the inductance measurement device 1 of the first embodiment was described using FIGS. 28 and 29 . In this fourth example, it was described that peaks of the rotating machine current Im of two phases can be detected during a predetermined carrier period Tc, which is the third current detection period Sd3 in one phase and the fourth current detection period Sd4 in the other phase. This predetermined carrier period Tc is represented by carrier periods 81d, 81e, and 81f in FIG. 28 . During carrier periods 81d, 81e, and 81f, which are the predetermined carrier period Tc, a positive peak in the rotating machine current Im of one phase can be detected on the side of the valley Pv at the starting end of the carrier period Tc, and a negative peak in the rotating machine current Im of the other phase can be detected on the side of the valley Pv at the ending end of the carrier period Tc. The negative peak in the U-phase rotating machine current Imu can be detected during carrier period 81f in FIG. 28 . In the period corresponding to the carrier period 81c shown in Figure 36, i.e., in the carrier period 81f, a negative peak of the U-phase (first phase) rotor current Imu can be detected near the valley Pv of the end of the carrier cycle Tc, i.e., toward time tc10. A positive peak of the V-phase (third phase) rotor current Imv can be detected near the valley Pv of the beginning of the carrier cycle Tc, i.e., toward time tc8. If the W-phase (second phase) rotor current Imw can be detected during the carrier period 81f, which is the period of the predetermined carrier cycle Tc, a current value near the positive peak of the V-phase rotor current Imv, i.e., a current value as close as possible to the positive peak, can be calculated using Kirchhoff's law. It will be described later that the current value calculated using Kirchhoff's law is a current value as close as possible to the positive peak of the third-phase rotor current Im.

[0220] During a carrier period 81f (see FIG. 28 ), which is a period of a predetermined carrier period Tc when the cycle end of the carrier signal 51 is at a valley Pv, the first phase of the rotating machine current Im, i.e., the detection target phase Pid1, for detecting a current value near the negative peak, is the U phase, and the second phase of the rotating machine current Im, i.e., the detection target phase Pid2, for detecting the rotating machine current Im, is the W phase. The rotating machine current Imu of the first phase, U phase, is detected at a value as close as possible to the negative peak, and the rotating machine current Imw of the second phase, W phase, is detected at a current value when the command value of the voltage command Vw* is maximum. The command value of the W-phase voltage command Vw* is greater than the command value of the U-phase voltage command Vu* and the command value of the V-phase voltage command Vv*, and the command value of the W-phase voltage command Vw* is maximum during this carrier period 81f. The W phase is the phase in which the command value of the voltage command Vw* is maximum, i.e., the maximum voltage phase.

[0221] By setting the detection timing Tg2 for detecting the rotating machine current Im of the second phase and the maximum voltage phase and detecting the rotating machine current Im of the maximum voltage phase, it is possible to detect a current close to the average value of the rotating machine current Im of the maximum voltage phase at the start (time tc8) of the carrier period 81f and the rotating machine current Im of the maximum voltage phase at the end (time tc10) of the carrier period 81f. As a result, the current of the remaining third phase, which is calculated according to Kirchhoff's law from the detected current value of the first phase at which the negative peak of the rotating machine current Im was detected and the detected current value of the second phase and the maximum voltage phase, becomes close to the current at the start (time tc8) of the carrier period 81f. Furthermore, in the third embodiment, the voltage commands Vu*, Vv*, and Vw* are three-phase components of the fundamental voltage command 119, which is a quasi-fundamental wave, the phase difference between the phases of the voltage commands Vu*, Vv*, and Vw* is 120°, the command period Tmc is six times the carrier period Tc, and the phases are rectangular wave voltages with equal voltage amplitudes. Therefore, the value of the third-phase rotating machine current Im calculated using Kirchhoff's law corresponds to the positive peak current value at the start of the carrier period 81c (time tc8) (see FIG. 28 ). Therefore, the third-phase rotating machine current Im calculated using Kirchhoff's law in the phase current output unit 31 is close to the positive peak value of the third-phase rotating machine current Im.

[0222] The method by which the timing determiner 35 determines whether the rotating machine current Im of a phase other than the detection target phase Pid1, i.e., the detection target phase Pid2, can be detected when the voltage command adjuster 39 and the PWM signal generator 33 perform a pulse shift of the on / off signal sg2 will be described. First, a case where the cycle end of the carrier signal 51 forms a crest Pp will be described, and then a case where the cycle end of the carrier signal 51 forms a valley Pv will be described. When the cycle end of the carrier signal 51 forms a crest Pp, the timing determiner 35 calculates a non-zero voltage vector application half time T3, which is half the non-zero voltage vector application time T1, during the carrier period Tc for detecting the rotating machine current Im of the adjustment target phase Dp when pulse shift is performed based on the adjustment target phase Dp and adjustment amount Ds determined by the adjustment amount determiner 36.

[0223] In the example of FIG. 36 , the adjustment target phase Dp is the U-phase, and the adjustment amount Ds of the U-phase, i.e., the adjustment amount Dsu, is the current detection time Tid. The detection target phase Pid1 is the U-phase, and the phase other than the detection target phase Pid1, i.e., the detection target phase Pid2, is the V-phase, which is the minimum voltage phase. The non-zero voltage vector application time of the first half of the carrier Trmf after the pulse shift is the first non-zero voltage vector application time T1f, and the non-zero voltage vector application time of the second half of the carrier Trms is the second non-zero voltage vector application time T1s. The first non-zero voltage vector application time T1f is the time from time t1 to time t4, and the second non-zero voltage vector application time T1s is the time from time t5 to time t7. The non-zero voltage vector application time T1 is the sum of the first non-zero voltage vector application time T1f and the second non-zero voltage vector application time T1s.

[0224] Here, if the non-zero voltage vector application time T1 is expressed using the non-zero voltage vector application half time T2 of the first half of the carrier Trmf before the shift and the non-zero voltage vector application half time T2 of the second half of the carrier Trms before the shift, it can be expressed as equation (1). Note that before the shift, the waveforms of the on / off signals Up2, Vp2, and Wp2 are symmetrical before and after the time at the midpoint of the carrier period Tc, i.e., the time of the valley Pv, so the non-zero voltage vector application half time T2 of the first half of the carrier Trmf before the shift and the non-zero voltage vector application half time T2 of the second half of the carrier Trms before the shift are equal. The non-zero voltage vector application half time T3 after the shift is expressed as equation (2). When the adjustment amount Dsu is the current detection time Tid, the non-zero voltage vector application half time T3 after the shift is expressed as equation (3). T1=Dsu+T2×2...(1) T3=T1 / 2=Dsu / 2+T2...(2) T3=Tid / 2+T2...(3)

[0225] In the example of FIG. 36 , the detection timing Tu for detecting a negative peak in the rotating machine current Imu of the U-phase, which is the detection target phase Pid1, is set to the first carrier first half Trmf. During a carrier period 81c, which is the period of the carrier cycle Tc, the U-phase is the point in time when the upper arm on / off signal sg2 first transitions from an off level to an on level. The reference point Prf is the point in time t1 when the U-phase upper arm on / off signal Up2 transitions from an off level to an on level. The timing determiner 35 determines that the V-phase, which is the minimum voltage phase, is detectable if the first non-zero voltage vector application time T1f, which begins at the reference point Prf and ends with the V-phase, which is the minimum voltage phase, is equal to or longer than the non-zero voltage vector application half time T3, and if the current detection time Tid for detecting the V-phase, which is the minimum voltage phase, can be secured after the non-zero voltage vector application half time T3 has elapsed. That is, the determination condition (first determination condition) when the cycle end of the carrier signal 51 is the peak Pp is that the following equation (4) is satisfied: T3+Tid≦T1f (4)

[0226] In the example of Figure 36, the period from time t3, which is half the time T3 of non-zero voltage vector application from the reference point Prf, to time t4, when the on-off signals Up2, Vp2, and Wp2 become non-zero voltage vectors, is equal to or longer than the current detection time Tid. Therefore, the detection timing Tg2 for detecting the rotor current Im of the V-phase, which is the minimum voltage phase, is set to the period when equation (4) is satisfied, that is, the period from time t3 after the current detection time Tid has elapsed until time t4. In the example of Figure 36, the detection timing Tg2 for detecting the rotor current Im of the detection phase Pid2, which is different from the detection phase Pid1, i.e., the rotor current Imv of the V-phase, which is different from the U-phase, is set to the time when the current detection time Tid has elapsed from time t3.

[0227] When the first determination condition is satisfied and the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2 is set, the timing determiner 35 calculates the centers of the non-zero voltage vector 123 in each of the first half (carrier first half Trmf) and second half (carrier second half Trms) of the carrier period Tc of the carrier signal 51, i.e., the center Taf of the first non-zero voltage vector application time T1f and the center Tas of the second non-zero voltage vector application time T1s. This can be explained as follows using the first voltage unit interval Tru1 and the second voltage unit interval Tru2. When setting the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, the timing determiner 35 calculates the first interval center Tn1 and the second interval center Tn2, which are the centers of the intervals in which the non-zero voltage vector 123 (non-zero switching command) is output, respectively, in the first voltage unit interval Tru1 and the second voltage unit interval Tru2 in one cycle of the carrier signal 51. As described in the first embodiment, the first half of the carrier Trmf is the first voltage unit interval Tru1 or the second voltage unit interval Tru2, and the second half of the carrier Trms is a voltage unit interval Tru different from the first half of the carrier Trmf. If the first half of the carrier Trmf is the first voltage unit interval Tru1, the second half of the carrier Trms is the second voltage unit interval Tru2, and if the first half of the carrier Trmf is the second voltage unit interval Tru2, the second half of the carrier Trms is the first voltage unit interval Tru1. When the cycle end of the carrier signal 51 shown in FIG. 36 is a peak Pp, the first half of the carrier Trmf is the first voltage unit interval Tru1, and the second half of the carrier Trms is the second voltage unit interval Tru2. On the other hand, when the cycle end of the carrier signal 51 shown in FIG. 29 is a valley Pv, the first half of the carrier Trmf is the second voltage unit interval Tru2, and the second half of the carrier Trms is the first voltage unit interval Tru1.

[0228] In the example of Fig. 36 , the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2 is set later in time than the period center Taf of the carrier first-half Trmf of the carrier period 81c. As shown in Fig. 36 , the timing determiner 35 determines the detection target phase Pid2 to be the minimum voltage phase, which is the phase in which the command value of the basic voltage command 119 is minimum in the carrier first-half Trmf, during the period of the carrier cycle Tc of the carrier signal 51 (carrier period 81c) that detects the negative peak of the rotating machine current Im of the detection target phase Pid1. In Fig. 36 , where the cycle end of the carrier signal 51 is a peak Pp, the period center Taf of the carrier first-half Trmf is the first section center Tn1 of the first voltage unit interval Tru1, and the period center Tas of the carrier second-half Trms is the second section center Tn2 of the second voltage unit interval Tru2.

[0229] When the first determination condition of Equation (4) is satisfied, the timing determination unit 35 determines a detection target phase Pid2 different from the detection target phase Pid1 and a detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, and outputs this information together with the previously determined detection target phase Pid1 and the detection timing Tg1 for detecting the rotating machine current Im of the detection target phase Pid1 to the phase current output unit 31. The inductance measurement device 1 of the third embodiment uses the detection target phase Pid1 alone or both the detection target phase Pid1 and the detection target phase Pid2 as the detection target phase Pid. Furthermore, the inductance measurement device 1 of the third embodiment uses the detection timing Tg1 alone or both the detection timing Tg1 and the detection timing Tg2 as the detection target phase Tg. Therefore, when the first judgment condition of equation (4) is satisfied, the timing determination unit 35 outputs to the phase current output unit 31 a detection timing signal sgs including information on the detection timing Tg1 and the detection timing Tg2, and a detection target phase signal sgp including information on the detection target phase Pid1 and the detection target phase Pid2.

[0230] In the above description, the timing determiner 35 determines the detection timing Tg2 for detecting the rotating machine current Im of a phase other than the detection target phase Pid1, i.e., the detection target phase Pid2, when the first determination condition of Equation (4) is satisfied. However, the timing determiner 35 may also determine the detection timing Tg2 based on the detection timing Tg1 of the detection target phase Pid1, at which the negative peak is detected instead of the reference point Prf. For example, assume that the detection timing Tg1 is set to a point in time t after the reference point Prf. That is, Tg1 = Prf + t. The detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, which is the minimum voltage phase, is determined to be detectable if the first non-zero voltage vector application time T1f is equal to half the non-zero voltage vector application time T3 + time t and the current detection time Tid for detecting the rotating machine current Im of the detection target phase Pid2, which is the minimum voltage phase, can be secured. That is, the determination condition (second determination condition) when the cycle end of the carrier signal 51 is the peak Pp is that the following equation (5) is satisfied: T3+t+Tid≦T1f (5)

[0231] When the first determination condition of Equation (4) or the second determination condition of Equation (5) is not satisfied, the timing determination unit 35 outputs a reset signal sgnt to the adjustment amount determination unit 36. Unlike in the first embodiment, the adjustment amount determination unit 36 ​​receives the reset signal sgnt as shown in FIG. 49 . Upon receiving the reset signal sgnt, the adjustment amount determination unit 36 ​​selects the adjustment target phase Dp and calculates the adjustment amount Ds again. Based on the adjustment target phase Dp and the adjustment amount Ds output again from the adjustment amount determination unit 36, the timing determination unit 35 determines whether the rotating machine current Im of a second phase different from the detection target phase Pid1, i.e., the detection target phase Pid2, can be detected when the voltage command adjustment unit 39 and the PWM signal generation unit 33 perform pulse shifting of the on / off signal sg2. When the first judgment condition of equation (4) or the second judgment condition of equation (5) is satisfied, the timing determination unit 35 determines the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, and outputs to the phase current output unit 31 a detection timing signal sgs including information on the detection timing Tg1 and the detection timing Tg2, and a detection target phase signal sgp including information on the detection target phase Pid1 and the detection target phase Pid2.

[0232] When the cycle end of the carrier signal 51 becomes a peak Pp, the timing determination unit 35 calculates a non-zero voltage vector application half time T3, which is half the non-zero voltage vector application time T1 during the carrier period Tc for detecting the rotating machine current Im of the adjustment target phase Dp when the voltage command adjustment unit 39 and the PWM signal generation unit 33 perform a pulse shift of the on / off signal sg2 based on the adjustment target phase Dp and adjustment amount Ds determined by the adjustment amount determination unit 36. When the first determination condition of Equation (4) or the second determination condition of Equation (5) is satisfied, the timing determiner 35 determines a detection target phase Pid2 different from the detection target phase Pid1 for detecting the negative peak of the rotating machine current Im and a detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, based on the non-zero voltage vector application half time T3, and outputs information on the detection target phase Pid2 and the detection timing Tg2 together with the previously determined detection target phase Pid1 and the detection timing Tg1 for detecting the rotating machine current Im of the detection target phase Pid1 to the phase current output unit 31. Therefore, when the first determination condition of Equation (4) or the second determination condition of Equation (5) is satisfied, the timing determiner 35 outputs a detection timing signal sgs including information on the detection timing Tg1 and the detection timing Tg2 and a detection target phase signal sgp including information on the detection target phase Pid1 and the detection target phase Pid2 to the phase current output unit 31 (current detection information output step). If the first determination condition of Equation (4) or the second determination condition of Equation (5) is not satisfied, the timing determination unit 35 outputs a reset signal sgnt to the adjustment amount determination unit 36. Thereafter, the timing determination unit 35 determines whether the rotating machine current Im of a second phase different from the detection target phase Pid1, i.e., the detection target phase Pid2, can be detected when the voltage command adjustment unit 39 and the PWM signal generation unit 33 perform pulse shifts of the on / off signal sg2 based on the adjustment target phase Dp and adjustment amount Ds output again from the adjustment amount determination unit 36 ​​(second phase detection determination step). This second phase detection determination step is performed a predetermined number of times until the rotating machine current Im of the detection target phase Pid2 becomes detectable, and if it becomes detectable, the timing determination unit 35 performs the current detection information output step.In addition, when the voltage command adjustment unit 39 and the PWM signal generation unit 33 perform a pulse shift of the on / off signal sg2 based on the first adjustment target phase Dp and adjustment amount Ds, the second phase detection determination process also includes a process of determining whether the rotating machine current Im of a second phase different from the detection target phase Pid1, i.e., the detection target phase Pid2, can be detected.

[0233] The timing determiner 35 determines whether the rotor current Im of a phase other than the target phase Pid1, i.e., the target phase Pid2, can be detected when the voltage command adjuster 39 and the PWM signal generator 33 perform pulse shifting of the on / off signal sg2 when the cycle end of the carrier signal 51 is at the valley Pv. As described above, the carrier period 81f in FIG. 28 corresponds to the carrier period 81c in FIGS. 35 and 36. When the cycle end of the carrier signal 51 is at the valley Pv, the detection timing Tg1 for detecting the negative peak of the rotor current Im of each phase is set to the second half Trms of the carrier. In this case, the reference point Prf is the point at which the upper arm on / off signal of one of the three phases first transitions from the on level to the off level. During the carrier period 81f, the U-phase upper arm on / off signal Up2 first transitions from the on level to the off level, and the maximum voltage phase is the W-phase. The timing determination unit 35 calculates a non-zero voltage vector application time T1 during which a non-zero voltage vector is applied from the reference point Prf, and a non-zero voltage vector application half time T3 which is half of this non-zero voltage vector application time T1. Note that in Figures 28 and 29, where the cycle end of the carrier signal 51 is the valley Pv, the period center Taf of the first half Trmf of the carrier is the second interval center Tn2 of the second voltage unit interval Tru2, and the period center Tas of the second half Trms of the carrier is the first interval center Tn1 of the first voltage unit interval Tru1.

[0234] The timing determination unit 35 determines that the rotating machine current Im of the maximum voltage phase is detectable if the second non-zero voltage vector application time T1s of the carrier latter half Trms is equal to or longer than the non-zero voltage vector application half time T3 and if the second non-zero voltage vector application time T1s can ensure a current detection time Tid for detecting the rotating machine current Im of the maximum voltage phase other than the non-zero voltage vector application half time T3. That is, the determination condition (third determination condition) when the cycle end of the carrier signal 51 is a valley Pv is satisfied: T3 + Tid ≦ T1s (6)

[0235] When the third determination condition of Equation (6) is satisfied, the timing determiner 35 sets the detection timing Tg2 for detecting the rotating machine current Im of the maximum voltage phase to immediately before the start of the zero voltage vector period Z1, as in the case where the cycle end of the carrier signal 51 is the peak Pp, or immediately after the end of the zero voltage vector period Z1, as opposed to the case where the cycle end of the carrier signal 51 is the peak Pp. Therefore, when the detection timing Tg2 is set to immediately after the end of the zero voltage vector period Z1, it is easy to understand if the end point of the non-zero voltage vector application half time T3 when the cycle end of the carrier signal 51 is the valley Pv is set to the end point of the current detection voltage vector period Q1, which includes Tg1 for detecting the negative peak. Furthermore, when the detection timing Tg2 for detecting the rotating machine current Im of the maximum voltage phase is set to immediately before the start of the zero voltage vector period Z1, the third determination condition can be set to Equation (4).

[0236] In the above description, when the cycle end of the carrier signal 51 corresponds to a valley Pv, the timing determiner 35 determines the detection timing Tg2 for detecting the rotating machine current Im of the detection target phase Pid2, i.e., the other phase different from the detection target phase Pid1, based on the third determination condition of Equation (6). However, the following fourth determination condition may al...

Claims

1. An inductance measuring device that applies an AC voltage to an inductive load and measures the inductance of the inductive load, comprising: a power conversion unit that receives DC power as input and converts it using a plurality of switching elements to supply the AC power to the inductive load; a current detection unit that detects a current flowing through a DC terminal of the power conversion unit; and a control unit that calculates a voltage command for the AC power when the AC voltage is applied to the inductive load, controls the power conversion unit using switching commands to the switching elements calculated based on the voltage command and a carrier signal, and detects a phase current of the inductive load using the DC current detected by the current detection unit while the power conversion unit is being controlled by the switching command, and is configured to calculate the inductance of the inductive load based on the detected value of the phase current and the voltage command; a vertex that is a maximum value and a vertex that is a minimum value in the carrier signal are defined as a first vertex and a second vertex, respectively, and the section between the adjacent first vertex and second vertex is defined as a voltage unit section; an inductance measuring device, wherein the voltage command or the AC voltage applied to the inductive load is set as a sign determination target, the timing of an end of the voltage unit interval at which the sign of the target to be determined is inverted is set as a sign inversion timing, and the phase of the AC voltage at which the sign is inverted at the sign inversion timing is set as a detection target phase of the phase current to be detected, and the control unit determines, based on a change tendency of the carrier signal before and after the sign inversion timing, to detect the phase current of the detection target phase in the voltage unit interval before the sign inversion timing or in the voltage unit interval after the sign inversion timing.

2. The inductance measuring device according to claim 1, wherein the intervals of one cycle of the carrier signal include a first voltage unit interval, which is the voltage unit interval in which the change tendency is such that the value decreases over time from the first peak toward the second peak, and a second voltage unit interval, which is continuous with the first voltage unit interval and is the voltage unit interval in which the change tendency is such that the value increases over time from the second peak toward the first peak; and wherein the control unit determines, as the detection target phase of the phase current to be detected, the phase of the AC voltage in which the sign reversal timing is the timing of the end end of the second voltage unit interval and the sign of the sign determination target reverses from positive to negative at the sign reversal timing, and determines to detect the phase current of the detection target phase in the second voltage unit interval located before the sign reversal timing.

3. The inductance measuring device according to claim 1, wherein the intervals of one cycle of the carrier signal include a first voltage unit interval, which is the voltage unit interval in which the change tendency is such that the value decreases over time from the first peak toward the second peak, and a second voltage unit interval, which is continuous with the first voltage unit interval and is the voltage unit interval in which the change tendency is such that the value increases over time from the second peak toward the first peak, and wherein the control unit determines, as the detection target phase of the phase current to be detected, the phase of the AC voltage in which the sign reversal timing is the timing of the start end of the first voltage unit interval and the sign of the sign determination target reverses from negative to positive at the sign reversal timing, and determines to detect the phase current of the detection target phase in the first voltage unit interval located after the sign reversal timing.

4. The inductance measuring device according to claim 1, wherein the intervals of one cycle of the carrier signal include a second voltage unit interval, which is the voltage unit interval in which the change tendency is such that the value increases over time from the second peak toward the first peak, and a first voltage unit interval, which is continuous with the second voltage unit interval and is the voltage unit interval in which the change tendency is such that the value decreases over time from the first peak toward the second peak, and wherein the control unit determines, as the detection target phase of the phase current to be detected, the phase of the AC voltage in which the sign reversal timing is the timing of the start end of the second voltage unit interval and the sign of the sign determination target reverses from positive to negative at the sign reversal timing, and determines to detect the phase current of the detection target phase in the second voltage unit interval located after the sign reversal timing.

5. The inductance measuring device according to claim 1, wherein the intervals of one cycle of the carrier signal include a second voltage unit interval, which is the voltage unit interval in which the change tendency is such that the value increases over time from the second peak toward the first peak, and a first voltage unit interval, which is continuous with the second voltage unit interval and is the voltage unit interval in which the change tendency is such that the value decreases over time from the first peak toward the second peak; and wherein the control unit determines, as the detection target phase of the phase current to be detected, the phase of the AC voltage in which the sign reversal timing is the timing of the end end of the first voltage unit interval and the sign of the sign determination target reverses from negative to positive at the sign reversal timing, and determines to detect the phase current of the detection target phase in the first voltage unit interval located before the sign reversal timing.

6. The inductance measuring device according to any one of claims 2 to 5, wherein the control unit comprises: a voltage command calculation unit that calculates the voltage command; a timing determination unit that determines the phase to be detected and a current detection timing for detecting the DC current reflecting the phase to be detected, based on a predetermined phase difference between the phase current of each phase flowing through the inductive load and the AC voltage of each phase applied to the inductive load, and the voltage command; and a voltage command adjustment unit that adjusts a voltage command value of the voltage command in the voltage unit interval in which the current detection timing for detecting the phase current of the phase to be detected occurs, to generate an adjusted voltage command including a current detection command for detecting the DC current of the phase to be detected.

7. The inductance measuring device according to claim 6, wherein the control unit comprises: a PWM signal generating unit that generates the switching command of a PWM signal corresponding to each of the switching elements of the power conversion unit; and an adjustment amount determining unit that determines the phase to be adjusted and the amount of adjustment for adjusting the voltage command based on the phase to be detected and the current detection timing; the voltage command adjusting unit generates the adjusted voltage command based on the carrier signal and the phase to be adjusted and the amount of adjustment determined by the adjustment amount determining unit; and the PWM signal generating unit generates the switching command based on the carrier signal and the adjusted voltage command.

8. The inductance measuring device according to claim 7, wherein a section of one cycle of the carrier signal has the first voltage unit section and the second voltage unit section, and the sign reversal timing is the timing of the first apex of the carrier signal, and wherein the timing determination unit, when the timing of the end of the second voltage unit section coincides with the sign reversal timing, determines the phase of the AC voltage where the sign of the object to be determined reverses from positive to negative at the sign reversal timing as the phase to be detected of the phase current to be detected, and when the timing of the start of the first voltage unit section coincides with the sign reversal timing, determines the phase of the AC voltage where the sign of the object to be determined reverses from negative to positive at the sign reversal timing as the phase to be detected of the phase current to be detected.

9. The inductance measuring device according to claim 7, wherein a section of one cycle of the carrier signal has the second voltage unit section and the first voltage unit section, and the sign reversal timing is the timing of the second apex of the carrier signal, and wherein the timing determination unit, when the timing of the start end of the second voltage unit section coincides with the sign reversal timing, determines the phase of the AC voltage where the sign of the object to be determined reverses from positive to negative at the sign reversal timing as the phase to be detected of the phase current to be detected, and when the timing of the end end of the first voltage unit section coincides with the sign reversal timing, determines the phase of the AC voltage where the sign of the object to be determined reverses from negative to positive at the sign reversal timing as the phase to be detected of the phase current to be detected.

10. The inductance measuring device according to claim 8, wherein the switching command to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero is a zero switching command, and the switching command to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero is a non-zero switching command, and the timing determination unit sets the current detection timing for detecting the current of the phase to be detected in the second voltage unit interval based on the adjusted voltage command and the carrier signal to immediately before the switching command is changed from the non-zero switching command to the zero switching command or to an end point of the second voltage unit interval, or sets the current detection timing for detecting the current of the phase to be detected in the first voltage unit interval based on the adjusted voltage command and the carrier signal to immediately after the minimum value of the current detection time during which the current of the phase to be detected is reflected in the DC current has elapsed, after the switching command is changed from the zero switching command to the non-zero switching command.

11. The inductance measuring device according to claim 9, wherein the switching command to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero is a zero switching command, and the switching command to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero is a non-zero switching command, and the timing determination unit sets the current detection timing for detecting the current of the phase to be detected in the second voltage unit interval to immediately after the minimum value of the current detection time during which the current of the phase to be detected is reflected in the DC current has elapsed after the switching command changes from the zero switching command to the non-zero switching command, based on the adjusted voltage command and the carrier signal, or sets the current detection timing for detecting the current of the phase to be detected in the first voltage unit interval to immediately before the switching command changes from the non-zero switching command to the zero switching command or to the end end of the first voltage unit interval, based on the adjusted voltage command and the carrier signal.

12. The number of phases of the AC power supplied by the power conversion unit to the inductive load is m, n is a natural number, the period of the voltage command is mn times the period of the carrier signal, the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero are zero switching commands, and the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero are non-zero switching commands, and the timing determination unit, when the timing of the start end of the first voltage unit interval is the sign reversal timing, determines the phase of the AC voltage at which the sign of the sign determination target reverses from negative to positive at the sign reversal timing as the detection target phase of the phase current to be detected, and in the first voltage unit interval, sets the current detection timing for detecting the current of the detection target phase to be immediately after the minimum value of the current detection time at which the current of the detection target phase is reflected in the DC current has passed after the switching command changes from the zero switching command to the non-zero switching command based on the adjusted voltage command and the carrier signal, 8. The inductance measurement device according to claim 7, wherein the phase of the AC voltage for which the command value of the voltage command is minimum in the first voltage unit section is determined as another phase to be detected, after a first section center that is the middle of the section in which a non-zero switching command is output in the first voltage unit section, and the current detection timing for detecting the current of the other phase to be detected is set to a timing after the first section center that the other phase to be detected is reflected in the DC current.

13. The number of phases of the AC power supplied by the power conversion unit to the inductive load is m, n is a natural number, the period of the voltage command is mn times the period of the carrier signal, the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero are zero switching commands, and the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero are non-zero switching commands, and the timing determination unit, when the timing of the end end of the first voltage unit interval is the sign reversal timing, determines the phase of the AC voltage at which the sign of the sign determination target reverses from negative to positive at the sign reversal timing as the detection target phase of the phase current to be detected, and in the first voltage unit interval, sets the current detection timing for detecting the current of the detection target phase to be immediately before the switching command is changed from the non-zero switching command to the zero switching command, or to the end end of the first voltage unit interval, based on the adjusted voltage command and the carrier signal, 8. The inductance measurement device according to claim 7, wherein a phase of the AC voltage in which the command value of the voltage command is maximum in the first voltage unit section is determined as another phase to be detected, temporally before a center of a first section that is the middle of a section in which a non-zero switching command is output in the first voltage unit section, and the current detection timing for detecting the current of the other phase to be detected is set to a timing, temporally before the center of the first section, in which the other phase to be detected is reflected in the DC current.

14. The number of phases of the AC power supplied by the power conversion unit to the inductive load is m, n is a natural number, the period of the voltage command is mn times the period of the carrier signal, the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero are zero switching commands, and the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero are non-zero switching commands, and the timing determination unit, when the timing of the end end of the second voltage unit interval is the sign reversal timing, determines the phase of the AC voltage at which the sign of the sign determination target reverses from positive to negative at the sign reversal timing as the detection target phase of the phase current to be detected, and in the second voltage unit interval, sets the current detection timing for detecting the current of the detection target phase to be immediately before the switching command is changed from the non-zero switching command to the zero switching command, or to the end end of the second voltage unit interval, based on the adjusted voltage command and the carrier signal, 8. The inductance measurement device according to claim 7, wherein a phase of the AC voltage for which the command value of the voltage command is minimum in the second voltage unit section is determined as another phase to be detected, temporally before a center of a second section that is the middle of a section in which a non-zero switching command is output in the second voltage unit section, and the current detection timing for detecting the current of the other phase to be detected is set to a timing, temporally before the center of the second section, at which the other phase to be detected is reflected in the DC current.

15. The number of phases of the AC power supplied by the power conversion unit to the inductive load is m, n is a natural number, the period of the voltage command is mn times the period of the carrier signal, the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current becomes zero are zero switching commands, and the switching commands to the plurality of switching elements based on the adjusted voltage command at which the DC current does not become zero are non-zero switching commands, and the timing determination unit, when the timing of the start end of the second voltage unit interval is the sign reversal timing, determines the phase of the AC voltage at which the sign of the sign determination target reverses from positive to negative at the sign reversal timing as the detection target phase of the phase current to be detected, and in the second voltage unit interval, sets the current detection timing for detecting the current of the detection target phase to be immediately after the minimum value of the current detection time at which the current of the detection target phase is reflected in the DC current has passed after the switching command changes from the zero switching command to the non-zero switching command based on the adjusted voltage command and the carrier signal, 8. The inductance measurement device according to claim 7, wherein the phase of the AC voltage for which the command value of the voltage command is maximum in the second voltage unit section is determined as another phase to be detected, after a second section center that is the middle of the section in which a non-zero switching command is output in the second voltage unit section, and the current detection timing for detecting the current of the other phase to be detected is set to a timing after the second section center that the other phase to be detected is reflected in the DC current.

16. An inductance measuring device according to any one of claims 6 to 15, wherein the control unit comprises: a phase current output unit that outputs the phase current flowing through the inductive load based on the DC current detected by the current detection unit; and an inductance calculation unit that calculates the inductance of the inductive load based on the phase current output by the phase current output unit and the voltage command generated by the voltage command calculation unit.

17. The control unit includes: a current change rate calculation unit that calculates a time rate of change for each of the phase currents of the inductive load; and a current correction unit that corrects the phase current based on the time rate of change for each of the phase currents and a correction time calculated by the timing determination unit, wherein when calculating the time rate of change for each of the phase currents, the current change rate calculation unit calculates the first time rate of change or the second time rate, and the current correction unit corrects the phase current using the first time rate of change or the second time rate, the first time rate of change is the time rate of change of the phase current corresponding to the switching element that is in the second state when the power conversion unit is controlled by the same voltage command as the voltage command input to the inductance calculation unit, and at least one of the plurality of switching elements connected to the negative DC terminal of the power conversion unit is in an on state, and the power conversion unit is in a second state when only one of the plurality of switching elements connected to the positive DC terminal of the power conversion unit is in an on state, and the second time rate of change is 17. The inductance measuring device according to claim 16, wherein, when the power conversion unit is controlled by the same voltage command as the voltage command input to the inductance calculation unit, and at least one of a plurality of switching elements connected to the positive DC terminal of the power conversion unit is in a third state in which it is on, and only one of a plurality of switching elements connected to the negative DC terminal of the power conversion unit is in a fourth state in which it is on, the time rate of change of the phase current corresponding to the switching element in the fourth state.

18. An inductance measurement method for measuring the inductance of an inductive load by applying an AC voltage to the inductive load using a power conversion unit, wherein the power conversion unit is configured to receive DC power as input and convert the converted AC power using a plurality of switching elements, and supply the converted AC power to the inductive load; the method includes: a power conversion unit control step of calculating a voltage command for the AC power to be applied to the inductive load, and controlling the power conversion unit using switching commands to the switching elements calculated based on the voltage command and a carrier signal; a phase current detection step of detecting a DC current flowing through a DC terminal of the power conversion unit using a current detection unit while the power conversion unit is being controlled by the power conversion unit control step, and detecting a phase current of the inductive load using the DC current; and an inductance calculation step of calculating the inductance of the inductive load based on the detected value of the phase current and the voltage command; wherein a vertex at a maximum value and a vertex at a minimum value in the carrier signal are defined as a first vertex and a second vertex, respectively, and the section between the adjacent first vertex and second vertex is defined as a voltage unit section; an inductance measurement method, the inductive load being a voltage command or an AC voltage applied to the inductive load, the voltage command or the AC voltage applied to the inductive load being a sign determination target, the timing of an end of the voltage unit interval at which the sign of the sign determination target is inverted being a sign inversion timing, the phase of the AC voltage at which the sign is inverted at the sign inversion timing being a detection target phase of the phase current to be detected, and the power conversion unit control step determining, based on a change tendency of the carrier signal before and after the sign inversion timing, to detect the phase current of the detection target phase in the voltage unit interval before the sign inversion timing or in the voltage unit interval after the sign inversion timing.

Images