Control device for AC rotating electric machines

Abstract

The present invention provides a control device for an AC rotating electric machine that can reduce the fluctuation range of the terminal voltage by finely changing the carrier frequency in response to an increase or decrease in the fluctuation range of the terminal voltage of a smoothing capacitor. [Solution] A control device for an AC rotating electric machine that calculates multi-phase voltage command values ​​to be applied to multi-phase armature windings, controls the on / off state of multiple switching elements in a power conversion circuit using PWM control based on the multi-phase voltage command values, estimates the voltage fluctuation range, which is the fluctuation range of the terminal voltage of the smoothing capacitor within one cycle of PWM control, and sets the setting time for the next PWM control cycle based on the voltage fluctuation range.

Description

Technical Field

[0001] The present disclosure relates to a control device for an AC rotating electric machine.

Background Art

[0002] The DC power of a DC power supply and the AC power of an AC rotating electric machine are mutually converted by on / off control of switching elements in a power conversion circuit. Since the DC current flowing between the DC power supply and the power conversion circuit may greatly fluctuate due to the switching of the switching elements, a smoothing capacitor is connected in parallel to the DC power supply in order to absorb this fluctuation. A fluctuating DC current flows in and out of the smoothing capacitor. The smoothing capacitor is charged and discharged due to the inflow and outflow of the DC current, and the voltage between the terminals of the smoothing capacitor fluctuates, but a large fluctuation in the voltage between the terminals is not preferable. For example, if the voltage between the terminals becomes too large due to the fluctuation in the voltage between the terminals, the withstand voltage of the smoothing capacitor or the switching element is exceeded. Alternatively, a large fluctuation in the voltage between the terminals may cause the DC power supply to be prone to aging or may have an adverse effect on other devices connected to the same DC power supply.

[0003] In the technique of Patent Document 1, the peak period of the fluctuation width of the voltage between the terminals of the smoothing capacitor generated by the switching of the switching element is estimated, and the carrier frequency is increased during the period including the peak period to reduce the peak value of the fluctuation width of the voltage between the terminals.

[0004] In the technique of Patent Document 2, among the three-phase voltage command values of a three-phase AC rotating electric machine, one on / off signal of the switching element of the phase whose voltage command value magnitude is intermediate is divided into a plurality of on / off signals so as to satisfy a predetermined criterion, thereby reducing the fluctuation width of the voltage between the terminals of the smoothing capacitor. [[ID=2,1]]

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] One possible way to reduce the voltage fluctuations across the terminals of a smoothing capacitor is to continuously increase the carrier frequency. However, increasing the carrier frequency increases the number of switching cycles, leading to increased switching losses, a decrease in power conversion efficiency, and a rise in temperature due to heat generation. Therefore, it is necessary to reduce the voltage fluctuations across the terminals of the smoothing capacitor while suppressing the increase in the number of switching cycles.

[0007] In the technology described in Patent Document 1, the carrier frequency is increased only during the period that includes the peak timing of the voltage fluctuation range across the terminals of the smoothing capacitor, thereby reducing the voltage fluctuation range across the terminals of the smoothing capacitor. Therefore, by only changing the carrier frequency in two stages, it is not possible to finely balance suppressing the increase in the number of switching cycles with reducing the voltage fluctuation range across the terminals of the smoothing capacitor. This is because the technology in Patent Document 1 only predicts the peak timing based on the current or electrical angle, and does not estimate the voltage fluctuation range across the terminals itself.

[0008] In the technology described in Patent Document 2, all on / off signals of the intermediate phase are divided, so the number of switching cycles increases at all times, regardless of whether the fluctuation range of the voltage across the terminals of the smoothing capacitor increases or decreases.

[0009] Therefore, the present disclosure aims to provide a control device for an AC rotating electric machine that can reduce the fluctuation range of the terminal voltage by finely changing the carrier frequency in response to an increase or decrease in the fluctuation range of the terminal voltage of the smoothing capacitor. [Means for solving the problem]

[0010] The control device for the AC rotating electric machine relating to this disclosure is A control device for an AC rotating electric machine having multiple phase armature windings, which controls the AC rotating electric machine via a power conversion circuit connected to a DC power supply and having a smoothing capacitor connected in parallel to the DC power supply, An output control unit calculates multi-phase voltage command values ​​to be applied to the multi-phase armature windings, and controls the on / off state of multiple switching elements in the power conversion circuit by PWM control based on the multi-phase voltage command values, A PWM period setting unit estimates the voltage fluctuation range, which is the voltage fluctuation range across the terminals of the smoothing capacitor within one cycle of the PWM control, and sets the setting time for the next and subsequent PWM control cycles based on the voltage fluctuation range. It is something that is provided. [Effects of the Invention]

[0011] According to the control device for an AC rotating electric machine described herein, the voltage fluctuation range, which is the fluctuation range of the voltage across the terminals of the smoothing capacitor, is estimated, and the setting time for the next PWM control cycle is set based on the estimated voltage fluctuation range. Therefore, the carrier frequency can be finely changed in accordance with the increase or decrease of the estimated voltage fluctuation range, and the voltage fluctuation range can be finely reduced. Thus, it is possible to finely balance the suppression of the increase in the number of switching cycles and the reduction of the voltage fluctuation range across the terminals of the smoothing capacitor. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of the AC rotating electric machine, power conversion circuit, and control device for the AC rotating electric machine according to Embodiment 1. [Figure 2] This is a schematic block diagram of the control device for an AC rotating electric machine according to Embodiment 1. [Figure 3] This is a hardware configuration diagram of the control device for an AC rotating electric machine according to Embodiment 1. [Figure 4] This is a block diagram of the output control unit according to Embodiment 1. [Figure 5] This is a time chart for explaining the estimation of voltage fluctuation range according to Embodiment 1. [Figure 6]Block diagram of the PWM period setting unit according to Embodiment 1. [Figure 7] Block diagram of the PWM period setting unit according to Embodiment 2. [Figure 8] Schematic configuration diagram of an AC rotating electric machine, a power conversion circuit, and a control device for the AC rotating electric machine according to Embodiment 3. [Figure 9] Schematic block diagram of the control device for the AC rotating electric machine according to Embodiment 3. [Figure 10] Block diagram of the PWM period setting unit according to Embodiment 3.

Embodiments for Carrying Out the Invention

[0013] 1. Embodiment 1 <Overall Configuration> Hereinafter, the control device 30 for an AC rotating electric machine according to Embodiment 1 (hereinafter simply referred to as the control device 30) will be described with reference to the drawings. FIG. 1 is a system configuration diagram showing a DC power supply 102, a power conversion circuit 1 having a smoothing capacitor 2, an AC rotating electric machine 103, and the control device 30.

[0014] 1-1. AC Rotating Electric Machine 103 The AC rotating electric machine 103 includes a stator 7 and a rotor 8 disposed radially inside the stator 7. The stator 7 is provided with a plurality of phase stator windings. In the present embodiment, three-phase stator windings Cu, Cv, and Cw of U-phase, V-phase, and W-phase are provided. The three-phase stator windings are star-connected. Note that the three-phase stator windings may be delta-connected. The AC rotating electric machine 103 is a permanent magnet type synchronous rotating electric machine, and the rotor 8 is provided with permanent magnets.

[0015] The AC rotating electric machine 103 includes an angle sensor 5 that outputs an electric signal according to the rotation angle of the rotor 8. The angle sensor 5 is a hall element, an encoder, a resolver, or the like. The output signal of the angle sensor 5 is input to the control device 30.

[0016] 1-2. DC Power Supply 102 The DC power supply 102 is connected to the power conversion circuit 1 and outputs a DC voltage Vpn to the power conversion circuit 1. The DC power supply 102 is a battery. Any device that outputs a DC voltage Vpn, such as an AC-DC converter, DC-DC converter, or PWM rectifier, is acceptable, as long as the voltage fluctuations of the DC voltage output by the device itself do not become the main cause of voltage fluctuations across the capacitor terminals due to switching in the power conversion circuit described later. A voltage sensor for detecting the DC voltage Vpn may also be provided.

[0017] 1-3. Power Conversion Circuit 1 The power conversion circuit 1 is a power converter that performs power conversion between a DC power supply 102 and three-phase armature windings, and has multiple switching elements. The power conversion circuit 1 includes a high-potential bus 14 connected to the high-potential side of the DC power supply 102 and a low-potential bus 15 connected to the low-potential side of the DC power supply 102. The power conversion circuit 1 has three series circuits (legs) in which a high-potential switching element 23H (upper arm) connected to the high-potential bus 14 and a low-potential switching element 23L (lower arm) connected to the low-potential bus 15 are connected in series, corresponding to the armature windings of each of the three phases. The connection point of two switching elements in the series circuit of each phase is connected to the armature winding of the corresponding phase.

[0018] Switching elements include IGBTs (Insulated Gate Bipolar Transistors) with diodes connected in antiparallel, FETs (Field Effect Transistors) with diodes connected in antiparallel, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) that function as diodes connected in antiparallel, and bipolar transistors with diodes connected in antiparallel. The gate terminal of each switching element is connected to the control device 30. Each switching element is turned on or off by a control signal output from the control device 30.

[0019] The power conversion circuit 1 includes a smoothing capacitor 2 connected in parallel to the DC power supply 102. That is, the smoothing capacitor 2 is connected between the high-potential bus 14 and the low-potential bus 15. When the switching element is turned on and off, the current flowing through the high-potential bus 14 and the low-potential bus 15 changes abruptly, but the smoothing capacitor 2 is provided to allow the fluctuating current to flow in and out so that not all of this current fluctuation becomes a fluctuation in the load current of the DC power supply 102.

[0020] The current sensor 4 outputs an electrical signal corresponding to the current flowing through the armature winding of each phase. The current sensor 4 is mounted on the wires of each phase connecting the series circuit of the switching element to the armature winding. The output signal of the current sensor 4 is input to the control device 30. The current sensor 4 may also be mounted in the series circuit of each phase.

[0021] 1-4. Control device 30 The control device 30 controls the AC rotating electric machine 103 via the power conversion circuit 1. As shown in Figure 2, the control device 30 includes a rotation detection unit 31, a current detection unit 32, an output control unit 33, and a PWM period setting unit 34, etc. Each function of the control device 30 is realized by the processing circuit provided in the control device 30. Specifically, as shown in Figure 3, the control device 30 includes a processing circuit such as a CPU (Central Processing Unit) or other arithmetic processing unit 90 (computer), a storage device 91 that exchanges data with the arithmetic processing unit 90, an input circuit 92 that inputs external signals to the arithmetic processing unit 90, and an output circuit 93 that outputs signals from the arithmetic processing unit 90 to the outside.

[0022] The arithmetic processing unit 90 may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. Furthermore, multiple arithmetic processing units 90 of the same or different types may be provided, with each unit performing a portion of the processing. The storage device 91 may include a RAM (Random Access Memory) configured to read and write data from the arithmetic processing unit 90, or a ROM (Read Only Memory) configured to read data from the arithmetic processing unit 90. The input circuit 92 is connected to various sensors such as an angle sensor 5 and a current sensor 4, and includes an A / D converter that inputs the output signals from these sensors to the arithmetic processing unit 90. The output circuit 93 is connected to electrical loads such as gate drive circuits that drive switching elements on and off, and includes drive circuits that output control signals from the arithmetic processing unit 90 to these electrical loads.

[0023] The functions of the control device 30, such as the processing units 31 to 34 shown in Figure 2, are realized by the arithmetic processing unit 90 executing software (programs) stored in the storage device 91, such as ROM, and cooperating with other hardware of the control device 30, such as the storage device 91, input circuit 92, and output circuit 93. The setting data used by each processing unit 31 to 34 is stored in the storage device 91, such as ROM. The functions of the control device 30 will be described in detail below.

[0024] <Rotation detection unit 31> The rotation detection unit 31 detects the rotor's electrical angle θe and electrical angular velocity ωe. In this embodiment, the rotation detection unit 31 detects the rotor's electrical angle θe and electrical angular velocity ωe based on the output signal of the angle sensor 5. The rotation detection unit 31 detects the electrical angle θe of the rotor's magnetic pole (N pole) with reference to the position of the U-phase armature winding. The rotation detection unit 31 may be configured to estimate the rotation angle without using a rotation sensor, based on current information obtained by superimposing harmonic components on the current command value (a so-called sensorless method). In this embodiment, the rotor's electrical angle θe and electrical angular velocity ωe are detected based on the output signal of the angle sensor 5 at the start of the PWM cycle.

[0025] <Current detection unit 32> The current detection unit 32 detects the currents iu, iv, and iw flowing through the three-phase armature windings based on the output signal of the current sensor 4. Alternatively, the current sensor 4 may be configured to detect the armature winding currents of two phases, and the remaining armature winding current of one phase may be calculated based on the detected values ​​of the two-phase armature winding currents. Here, the direction of the current flowing from the power conversion circuit 1 to the armature windings is defined as positive, and the direction of the current flowing from the armature windings to the power conversion circuit 1 is defined as negative. In this embodiment, the three-phase current detection values ​​iu, iv, and iw are detected based on the output signal of the current sensor 4 at the start of the PWM cycle.

[0026] <Output control unit 33> The output control unit 33 calculates the three-phase voltage command values ​​vu*, vv*, and vw* to be applied to the three-phase armature windings, and controls the on / off state of the multiple switching elements of the power conversion circuit 1 using PWM control based on the three-phase voltage command values ​​vu*, vv*, and vw*.

[0027] In this embodiment, based on the electrical angle θe, electrical angular velocity ωe, and three-phase current detection values ​​iu, iv, iw, etc., detected at the start of the PWM cycle, three-phase voltage command values ​​vu*, vv*, and vw* are calculated during the PWM cycle, and the calculated three-phase voltage command values ​​vu*, vv*, and vw* are reflected in the PWM control in subsequent PWM cycles.

[0028] In this embodiment, as shown in Figure 4, the output control unit 33 includes a current command value calculation unit 331, a voltage command value calculation unit 332, a voltage conversion unit 333, a current conversion unit 334, and a PWM control unit 335.

[0029] <Current command value calculation unit 331> The current command value calculation unit 331 calculates the d-axis current command value id* and the q-axis current command value iq* based on a given torque command value τ* and electrical angular velocity ωe, such that the torque τ of the AC rotating electric machine 103 matches the torque command value τ*. The d-axis is defined in the direction of the rotor's magnetic flux (direction of the magnetic pole (N pole)), and the q-axis is defined in a direction advanced by π / 2 electrical angle from the d-axis.

[0030] <Current conversion unit 334> The current conversion unit 334 converts the three-phase current detection values ​​iu, iv, and iw into a d-axis current detection value id and a q-axis current detection value iq by performing known three-phase to two-phase conversion and rotational coordinate transformation based on the electrical angle θe.

[0031] <Voltage command value calculation unit 332> The voltage command value calculation unit 332 performs feedback control, such as PI control, to change the voltage command value vd* for the d axis and the voltage command value vq* for the q axis so that the current detection value id for the d axis and the current detection value iq for the q axis approach the current command value id* for the d axis and the current command value iq* for the q axis, respectively. Known feedforward control may also be used.

[0032] <Voltage conversion unit 333> The voltage conversion unit 333 converts the voltage command values ​​vd* on the d axis and vq* on the q axis into three-phase voltage command values ​​vu*, vv*, and vw* by performing known fixed coordinate transformations and two-phase to three-phase transformations based on the electrical angle θe. Note that the three-phase voltage command values ​​vu*, vv*, and vw* oscillate around 0.

[0033] For the three-phase voltage command values vu*, vv*, and vw*, amplitude reduction modulation may be added to superimpose an offset voltage that reduces the amplitude of the three-phase voltage command values while maintaining the line voltage. As the amplitude reduction modulation, third-harmonic superposition, min-max method (pseudo-third-harmonic superposition), or two-phase modulation, etc. is used. In third-harmonic superposition, an offset voltage of a sine wave with a period three times that of the electrical angle rotation period is superimposed on the three-phase voltage command values. In the min-max method (pseudo-third-harmonic superposition), an offset voltage of a triangular wave with a period three times that of the electrical angle rotation period is superimposed on the three-phase voltage command values. In two-phase modulation, an offset voltage such that the voltage command value of the lowest potential or the highest potential coincides with the low potential side (in this example, -Vpn / 2) or the high potential side (in this example, +Vpn / 2) of the DC voltage is superimposed on the three-phase voltage command values. For convenience of explanation, the three-phase voltage command values after modulation are also simply referred to as the three-phase voltage command values. Note that the amplitude reduction modulation may be performed after converting the voltage command value of each phase into the duty ratio of PWM control.

[0034] <PWM control unit 335> Based on the three-phase voltage command values vu*, vv*, and vw*, the PWM control unit 335 performs on / off control of a plurality of switching elements included in the power conversion circuit 1 by PWM control. Known carrier comparison PWM control is used.

[0035] In this embodiment, the PWM control unit 335 divides each of the three-phase voltage command values vu*, vv*, and vw* by the DC voltage Vpn, then adds 0.5 to convert them into the duty ratio of PWM control, compares each of the three-phase duty ratios with a carrier wave that oscillates between the duty ratios 0 and 1 within the set time Tc of the PWM period, and performs on / off control of the high-potential side and low-potential side switching elements of each phase based on the comparison result of each phase. The PWM period coincides with the period of the carrier wave (carrier period).

[0036] <Duty conversion> In this embodiment, as shown in the following equation, the PWM control unit 335 divides each of the three-phase voltage command values ​​vu*, vv*, and vw* by the DC voltage Vpn, then adds 0.5 to convert them into PWM control duty cycles, and calculates the duty cycles du, dv, and dw of the three-phase voltage command values. Here, the duty cycle is the on-duty cycle when the high-potential switching element (upper arm) is turned on, and the off-duty cycle when the low-potential switching element (lower arm) is turned off.

number

[0037] <Carrier generation> The PWM control unit 335 generates a carrier wave cnt that oscillates between a duty cycle of 0 and 1 at the set time Tc of the PWM period set by the PWM period setting unit 34. The carrier wave cnt is a triangular wave.

[0038] The PWM period is the period during which the pulse wave is switched on and off once in PWM control. In this embodiment, the start and end points of the PWM period are the trough (0) of the carrier wave cnt, the period from the start to the end point of the PWM period is the set time Tc of the PWM period, and the reciprocal of the set time Tc of the PWM period is the frequency fc of the PWM period. Note that the start and end points of the PWM period may also be the peak (1) of the carrier wave cnt.

[0039] The PWM control unit 335 sets the PWM period setting time Tc used for generating the carrier wave cnt to the latest PWM period setting time Tc calculated by the PWM period setting unit 34 in the previous PWM period at the start of the PWM period, and generates the carrier wave cnt using the set PWM period setting time Tc from the start to the end of that PWM period.

[0040] <Carrier Comparison PWM Control> For each phase, when the carrier wave cnt is lower than the duty ratio d of the voltage command value, the PWM control unit 335 turns on the switching signal of the high-potential side switching element (upper arm) to turn on the high-potential side switching element. When the carrier wave cnt is higher than the duty ratio d of the voltage command value, the PWM control unit 335 turns off the switching signal of the high-potential side switching element to turn off the high-potential side switching element. On the other hand, for each phase, when the carrier wave cnt is lower than the duty ratio d of the voltage command value, the PWM control unit 335 turns off the switching signal of the low-potential side switching element (lower arm) to turn off the low-potential side switching element. When the carrier wave cnt is higher than the duty ratio d of the voltage command value, the PWM control unit 335 turns on the switching signal of the low-potential side switching element to turn on the low-potential side switching element. Note that for each phase, a short-circuit prevention period (dead time) during which both the high-potential side and low-potential side switching elements are turned off may be provided between the on period of the high-potential side switching element and the on period of the low-potential side switching element.

[0041] Note that the PWM control unit 335 may compare each of the three-phase voltage command values vu*, vv*, vw* with a carrier wave having an amplitude of half the DC voltage value Vpn / 2 centered on 0 and vibrating at the set time Tc of the PWM period, and perform on / off control of the high-potential side and low-potential side switching elements of each phase based on the comparison result of each phase.

[0042] <Principle Explanation of PWM Period Setting Unit 34> First, we will explain the principle of the PWM period setting unit 34. We will explain the terminology necessary for this principle explanation. Regarding the duty cycles of the three phase voltage command values, we will assign sequential numbers starting from 1 to the phases with the smallest duty cycles. That is, among the duty cycles of the three phase voltage command values, the phase with the smallest duty cycle is called the first phase, the phase with the second smallest duty cycle is called the second phase, and the phase with the largest duty cycle is called the third phase. Corresponding to the sequential numbers of the phases, the duty cycles of the three phase voltage command values ​​will be called the duty cycle d1 of the first phase voltage command value, the duty cycle d2 of the second phase voltage command value, and the duty cycle d3 of the third phase voltage command value, in order from the phase with the smallest duty cycle. Similarly, the current detection values ​​of the three phases will be called the current detection value i1 of the first phase, the current detection value i2 of the second phase, and the current detection value i3 of the third phase, in order from the phase with the smallest duty cycle. If there are multiple phases with the same duty cycle, these identical phases are numbered in any order.

[0043] As described above, the PWM period is the period during which the pulse wave is switched on and off once in PWM control. In this embodiment, the start and end points of the PWM period are the bottom (0) of the trough of the carrier wave cnt, and the period from the start to the end point of the PWM period is the set time Tc of the PWM period.

[0044] As shown in Figure 5, during one PWM period, while the carrier wave cnt increases from 0 to 1, the state changes sequentially from the first to the third phase, from a state where the upper arm of each phase is on and the lower arm is off, to a state where the upper arm of each phase is off and the lower arm is on. Subsequently, while the carrier wave cnt decreases from 1 to 0, the state changes sequentially from the first to the third phase, from a state where the upper arm of each phase is off and the lower arm is on, to a state where the upper arm of each phase is on and the lower arm is off.

[0045] Here, the duty cycle of each phase and the set time Tc of the PWM period are updated at the start of the PWM period. Since the duty cycle of each phase is constant within one PWM period, the first half of the PWM period (while the carrier wave cnt is increasing) and the second half (while the carrier wave cnt is decreasing) are symmetrical. Therefore, in Figure 5, the behavior of current and voltage will be explained for the first half of the PWM period.

[0046] As shown in the top graph of Figure 5, the interval from the start of the PWM period to the point when the carrier wave cnt is equal to or greater than the duty cycle d1 of the first phase is defined as the first interval, and the duration (time) of the first interval is defined as P1. The interval from the point when the carrier wave cnt is equal to or greater than the duty cycle d1 of the first phase to the point when the carrier wave cnt is equal to or greater than the duty cycle d2 of the second phase is defined as the second interval, and the duration (time) of the second interval is defined as P2. The interval from the point when the carrier wave cnt is equal to or greater than the duty cycle d2 of the second phase to the point when the carrier wave cnt is equal to or greater than the duty cycle d3 of the third phase is defined as the third interval, and the duration (time) of the third interval is defined as P3. The interval from the point when the carrier wave cnt is equal to or greater than the duty cycle d3 of the third phase to the midpoint of the PWM period is defined as the fourth interval, and the duration (time) of the fourth interval is defined as P4.

[0047] The periods P1 to P4 from the first to the fourth interval can be expressed by the following equation, using the duty cycles d1 to d3 of the first to third phases and the set time Tc of the PWM period.

number

[0048] The currents charged and discharged from the three-phase armature windings to the smoothing capacitor 2 via the power conversion circuit 1 are as follows for each interval from the first to the fourth interval. As shown in the second row of the graph in Figure 5, in the first interval, the upper arms of all phases are ON and the lower arms of all phases are OFF. Therefore, all currents flowing from the power conversion circuit 1 to the three-phase armature windings flow from the high-potential side. That is, the sum of the three-phase currents is zero, so the currents charged and discharged from the three-phase armature windings to the smoothing capacitor 2 in the first interval are zero.

[0049] In the second interval, the upper arm of the first phase is off and the lower arm is on, while the upper arms of the second and third phases are on and the lower arms are off. Therefore, the sum of the currents i2 and i3 of the second and third phases flows from the high-potential side of the power conversion circuit 1 to the armature windings of the second and third phases. The sign-inverted value of the current i1 of the first phase flows from the armature winding of the first phase to the low-potential side of the power conversion circuit 1. In other words, in the second interval, the current charged and discharged from the three-phase armature windings to the smoothing capacitor 2 is -i2-i3 (or i1).

[0050] In the third interval, the upper arm of the third phase is ON and the lower arm is OFF, while the upper arms of the first and second phases are OFF and the lower arms are ON. Therefore, the current of the third phase flows from the high-potential side of the power conversion circuit 1 to the armature winding of the third phase. The sign-inverted value of the sum of the currents i1 and i2 of the first and second phases flows from the armature winding of the first phase to the low-potential side of the power conversion circuit 1. That is, in the second interval, the current charged and discharged from the three-phase armature windings to the smoothing capacitor 2 is -i3 (or i1 + i2).

[0051] In the fourth interval, the upper arms of all phases are off, and the lower arms are on. Therefore, all currents flowing from the power conversion circuit 1 to the three-phase armature windings flow from the low-potential side. That is, the sum of the three phase currents is zero, so in the fourth interval, the current charging and discharging from the three-phase armature windings to the smoothing capacitor 2 is zero.

[0052] Incidentally, the smoothing capacitor 2 receives a current from the DC power supply 102 that is equal to the current supplied to the three-phase armature windings on a time-averaged basis. Assuming that the current idc flowing from the DC power supply 102 to the smoothing capacitor 2 is equal to the current supplied to the three-phase armature windings during one PWM period, the following equations hold. Note that in equations (3), (4), and (5), i1 may be replaced with -i2-i3, and i3 may be replaced with -i1-i2.

number

[0053] Based on the above, the sum of the current idc flowing from the DC power supply 102 to the smoothing capacitor 2 and the current flowing from the three-phase armature winding to the smoothing capacitor 2 is given by the following equation for each interval.

number

[0054] Here, regarding the voltage change across the smoothing capacitor 2, if we let ΔV1 be the voltage change over the first interval, ΔV2 be the voltage change over the second interval, ΔV3 be the voltage change over the third interval, and ΔV4 be the voltage change over the fourth interval, then the calculation can be performed as follows. Here, C is the capacitance of the smoothing capacitor 2.

number

[0055] Furthermore, regarding the voltage across the terminals of the smoothing capacitor 2, if we let V1 be the voltage fluctuation from the start of the PWM period at the end of the first interval, V2 be the voltage fluctuation from the start of the PWM period at the end of the second interval, and V3 be the voltage fluctuation from the start of the PWM period at the end of the third interval, then it can be expressed as follows.

number

[0056] The terminal voltage of smoothing capacitor 2 in the latter half of the PWM period has symmetry with the terminal voltage of smoothing capacitor 2 in the first half of the PWM period, rotated by 180 degrees.

[0057] The voltage fluctuation range Vpp of the terminal voltage of smoothing capacitor 2 during one PWM period consisting of a first half and a second half is the difference between the maximum voltage and the minimum voltage. Due to symmetry, the absolute value of the minimum voltage in the first half and the absolute value of the maximum voltage in the second half are the same. Therefore, the voltage fluctuation range Vpp is twice the value of the voltage fluctuation with the largest absolute value among the voltage fluctuations V1 to V3.

[0058] This voltage fluctuation width Vpp is proportional to the set time Tc of the PWM period if the operating conditions other than the set time Tc of the PWM period are the same. For example, if the set time Tc of the PWM period is halved, the voltage fluctuation width Vpp is halved.

[0059] The PWM period setting unit 34 calculates the set time Tc of the PWM period such that the desired voltage fluctuation width Vpp is obtained by using the above property.

[0060] <Configuration of PWM period setting unit 34> The PWM period setting unit 34 estimates the voltage fluctuation width Vpp, which is the fluctuation width of the voltage between the terminals of the smoothing capacitor 2 within one PWM period, and sets the set time Tc of the PWM period for the next and subsequent PWM periods based on the voltage fluctuation width Vpp.

[0061] According to this configuration, since the voltage fluctuation width Vpp is estimated and the set time Tc of the period of PWM control for the next and subsequent times is set based on the estimated voltage fluctuation width Vpp, the carrier frequency fc can be finely changed according to the increase or decrease of the estimated voltage fluctuation width Vpp, and the voltage fluctuation width Vpp can be finely reduced. It is possible to finely balance the suppression of the increase in the number of switching operations and the reduction of the fluctuation width of the voltage between the terminals of the smoothing capacitor.

[0062] In the present embodiment, the PWM period setting unit 34 estimates a specific voltage fluctuation width Vppsp when it is assumed that a specific set time Tcsp of the PWM period is set as the set time Tc of the PWM period. The PWM period setting unit 34 decreases the set time Tc of the PWM period as the estimated specific voltage fluctuation width Vppsp increases.

[0063] According to this configuration, as the specific voltage fluctuation width Vppsp when it is assumed that the specific set time Tcsp of the PWM period is set becomes larger, by decreasing the set time Tc of the PWM period, it is possible to suppress the actual voltage fluctuation width from becoming large.

[0064] Then, the PWM period setting unit 34 sets the setting time Tc for the next and subsequent PWM periods based on a specific voltage fluctuation range Vppsp assuming that a specific PWM period setting time Tcsp is set, a target voltage fluctuation range Vpp*, and the specific PWM period setting time Tcsp.

[0065] With this configuration, the PWM period setting time Tc corresponding to the target voltage fluctuation range Vpp* can be set based on the relationship between a specific voltage fluctuation range Vppsp, a target voltage fluctuation range Vpp*, and a specific PWM period setting time Tcsp.

[0066] The PWM period setting unit 34 sets the setting time Tc for the next and subsequent PWM periods by multiplying the ratio of the target voltage fluctuation range Vpp* to the estimated specific voltage fluctuation range Vppsp by the setting time Tcsp of a specific PWM period.

[0067] With this configuration, the PWM period setting time Tc can be set so that the actual voltage fluctuation range Vpp matches the target voltage fluctuation range Vpp*.

[0068] The PWM period setting unit 34 estimates the voltage fluctuation range Vpp using the duty cycles du, dv, and dw of the three-phase PWM control corresponding to the three-phase voltage command values ​​vu*, vv*, and vw*, and the currents iu, iv, and iw flowing through the three-phase armature windings.

[0069] As explained using equations (2) to (6), the voltage fluctuation range Vpp can be calculated based on the duty cycles du, dv, and dw of the three-phase PWM control, the three-phase current detection values ​​iu, iv, and iw, and the PWM period setting time Tc. Therefore, the voltage fluctuation range Vpp corresponding to the current operating state can be estimated using the duty cycles du, dv, and dw of the three-phase PWM control and the three-phase current detection values ​​iu, iv, and iw.

[0070] In this embodiment, the PWM period setting unit 34 assigns sequential numbers to the duty cycles du, dv, and dw of the three-phase PWM control, starting from the phase with the smallest duty cycle. Using the sequentially numbered duty cycles d1, d2, and d3 of the first, second, and third phases, and the sequentially numbered current detection values ​​i1, i2, and i3 of the first, second, and third phases, the unit estimates the voltage fluctuation range Vpp.

[0071] With this configuration, as explained using equations (2) to (6), sequential numbers are assigned to the phases with the smallest duty cycle, and by using the duty cycles and current detection values ​​of the sequentially numbered first, second, and third phases, the voltage fluctuation range Vpp can be estimated using the same calculation formula.

[0072] As shown in Figure 6, in this embodiment, the PWM period setting unit 34 includes an alignment processing unit 341, a period calculation unit 342, a DC current calculation unit 343, an interval voltage change calculation unit 344, a voltage fluctuation amount calculation unit 345, a voltage fluctuation width calculation unit 346, and a PWM period calculation unit 347.

[0073] The alignment processing unit 341 assigns sequential numbers starting from 1 to the duty cycles du, dv, and dw of the three-phase PWM control, in order from the phase with the smallest duty cycle. As described above, the alignment processing unit 341 sets the phase with the smallest duty cycle among the duty cycles of the three-phase voltage command values ​​as the first phase, the phase with the second smallest duty cycle as the second phase, and the phase with the largest duty cycle as the third phase. Corresponding to the sequential numbers of the phases, the alignment processing unit 341 sets the duty cycles of the three-phase voltage command values ​​in order from the phase with the smallest duty cycle as d1 for the first phase voltage command value, d2 for the second phase voltage command value, and d3 for the third phase voltage command value. Similarly, the alignment processing unit 341 sets the current detection values ​​iu, iv, and iw for the three phases in order from the phase with the smallest duty cycle, corresponding to the sequential number of the phases, as follows: the current detection value i1 for the first phase, the current detection value i2 for the second phase, and the current detection value i3 for the third phase. If there are multiple phases with the same duty cycle, these multiple identical phases are numbered in an arbitrary order.

[0074] The period calculation unit 342 uses equation (2) to calculate the periods P1 for the first interval, P2 for the second interval, P3 for the third interval, and P4 for the fourth interval, based on the duty cycle d1 of the first phase, the duty cycle d2 of the second phase, the duty cycle d3 of the third phase, and the setting time Tcsp of a specific PWM period. In equation (2), the setting time Tcsp of a specific PWM period is used instead of the setting time Tc of the PWM period.

[0075] In this embodiment, the preset reference PWM period setting time Tc0 is used as the setting time Tcsp for a specific PWM period. Alternatively, the setting time Tcsp for a specific PWM period may be the current PWM period setting time Tcnow, or 1 or 2, or the capacitance C of the smoothing capacitor 2, or any other arbitrary value. Using 1 or 2 simplifies the calculations in equations (2), (3), and (8), and reduces the computational load. Using capacitance C cancels out the C in the denominator of equation (5).

[0076] The DC current calculation unit 343 calculates the DC current idc using equation (3) based on the third interval period P3, the third phase current detection value i3, the second interval period P2, the first phase current detection value i1, and the specific PWM period setting time Tcsp. In equation (3), the specific PWM period setting time Tcsp is used instead of the PWM period setting time Tc. -i2-i3 may be used instead of i1, and -i1-i2 may be used instead of i3.

[0077] The interval voltage change calculation unit 344 uses equation (5) to calculate the voltage change ΔV1 for the first interval, the voltage change ΔV2 for the second interval, the voltage change ΔV3 for the third interval, and the voltage change ΔV4 for the fourth interval, based on the DC current idc, the current detection value i1 for the first phase, the current detection value i3 for the third phase, and the periods P1, P2, P3, and P4 from the first to the fourth interval. The capacitance C of the smoothing capacitor 2 is set in advance. Instead of i1, -i2-i3 may be used, and instead of i3, -i1-i2 may be used.

[0078] The voltage fluctuation calculation unit 345 uses equation (6) to calculate the voltage fluctuation amount V1 from the start of the PWM period at the end of the first interval, the voltage fluctuation amount V2 from the start of the PWM period at the end of the second interval, and the voltage fluctuation amount V3 from the start of the PWM period at the end of the third interval, based on the voltage change ΔV1 in the first interval, the voltage change ΔV2 in the second interval, and the voltage change ΔV3 in the third interval.

[0079] The voltage fluctuation range calculation unit 346 estimates a specific voltage fluctuation range Vppsp as twice the maximum value among the absolute values ​​of the voltage fluctuation amount V1 at the end of the first interval, the absolute value of the voltage fluctuation amount V2 at the end of the second interval, and the absolute value of the voltage fluctuation amount V3 at the end of the third interval, as shown in the following equation.

number

[0080] As shown in the following equation, the PWM period calculation unit 347 calculates the value obtained by multiplying the ratio of the target voltage fluctuation width Vpp* to a specific voltage fluctuation width Vppsp by the setting time Tcsp of a specific PWM period, and uses this value as the setting time Tctmp of the PWM period before the limit.

number

[0081] As can be seen from equations (2) to (5), the specific voltage fluctuation range Vppsp in the denominator of equation (8) is proportional to the setting time Tcsp of a specific PWM period, and the numerator of equation (8) is multiplied by the setting time Tcsp of a specific PWM period. Therefore, no matter what value is set for the setting time Tcsp of a specific PWM period, the result of the calculation in equation (8) will be the same. For this reason, as mentioned above, the setting time Tcsp of a specific PWM period may be the pre-set setting time Tc0 of a PWM period, the current setting time Tcnow of a PWM period set at the current PWM period, 1 or 2, capacitance C, or any other arbitrary value.

[0082] On the other hand, since various controls are performed in conjunction with the PWM period, if the PWM period setting time Tc becomes excessively large, the control performance deteriorates.

[0083] Therefore, the PWM period calculation unit 347 sets the final PWM period setting time Tc to a value obtained by limiting the pre-limit PWM period setting time Tctmp by the upper limit period Tcmax, as shown in the following equation. This prevents the PWM period setting time Tc from becoming too large. A lower limit may also be applied.

number

[0084] The calculated PWM period setting time Tc is reflected in the generation of the carrier wave cnt for subsequent PWM periods. In this embodiment, the PWM period setting unit 34 sets the PWM period setting time Tc for each PWM period after the three-phase voltage command values ​​vu*, vv*, and vw* have been calculated during the PWM period, and reflects this in the generation of the carrier wave cnt for the next PWM period. Alternatively, the PWM period setting unit 34 may set the PWM period setting time Tc for multiple (for example, two) PWM periods and reflect this in the generation of the carrier wave cnt for subsequent PWM periods until the next PWM period setting time Tc is set.

[0085] 2. Embodiment 2 The control device 30 and AC rotating electric machine 103 according to Embodiment 2 will now be described. The same components as in Embodiment 1 will not be described. The basic configuration of the control device 30 and AC rotating electric machine 103 according to this embodiment is the same as in Embodiment 1, but the calculation processing of the PWM period setting unit 34 differs from that of Embodiment 1.

[0086] <Changes in voltage fluctuation range within one rotation period of the electrical angle> One of the main objectives of this embodiment is to minimize the voltage fluctuation range Vpp while bringing the average number of switching cycles of the switching element within one rotation period of the electrical angle closer to the target number. Therefore, we will first explain the voltage fluctuation range within one rotation period of the electrical angle.

[0087] The voltage fluctuation range Vpp in a specific PWM period with a one-rotation period of the electrical angle is twice the value of the largest absolute value among the voltage fluctuations V1 to V3 in equation (6). This explains what happens with a one-rotation period of the electrical angle.

[0088] Assume that the current waveforms and line-to-line voltage waveforms of each phase with respect to one rotation period of the electrical angle are sinusoidal. Furthermore, assuming that amplitude reduction modulation is not performed and the voltage command values ​​of the three phases are sinusoidal, let I be the amplitude of the current in each phase, θ be the phase of the voltage command value of a specific phase (in this example, the U phase), ψ be the power factor angle, and M be the modulation ratio. Then the currents of each phase and the duty cycles of each phase are given by equations (10) and (11). The phase θ of the voltage command value of the U phase is the phase (electrical angle) of the voltage command value of the U phase with respect to the winding position of the U phase.

number

number

[0089] Within a 60-degree range of the electrical angle's rotation period, considering the relative magnitudes of the duty cycles of the three phases, the following equations are obtained from equations (10) and (11), and from equations (2) to (6), to calculate the absolute values ​​of the voltage fluctuations of the first to third phases |V1|, |V2|, and |V3|. Here, MOD(θ, π / 3) is a function that outputs the remainder when the phase θ of the voltage command value of a particular phase is divided by π / 3, and this remainder is set as θ'. For example, if θ is 70 degrees, the remainder of 70 degrees divided by 60 degrees, which is 10 degrees, is set as θ'. If θ is 150 degrees, the remainder of 150 degrees divided by 60 degrees, which is 30 degrees, is set as θ'. More precisely, within each 60-degree range, the right-hand sides of |V1| and |V3| in equation (12) are swapped, but since a specific voltage fluctuation range Vppsp is calculated using the maximum values ​​of |V1| and |V3|, the specific voltage fluctuation range Vppsp is calculated correctly.

number

[0090] Considering the latter half of the PWM period, assuming that a specific PWM period setting time Tcsp is set as the PWM period setting time Tc, the specific voltage fluctuation range Vppsp for one PWM period will be twice the maximum of the absolute values ​​of the voltage fluctuation amounts |V1| to |V3| in equation (12), as shown in the following equation.

number

[0091] The integral values ​​of specific voltage fluctuations Vppsp within each 60-degree range are the same because equation (12) is the same. Therefore, as shown in the first equation below, the integral value of a specific voltage fluctuation within the electrical angle range of 0 to 60 degrees of the phase θ of the voltage command value of a specific phase is calculated as a representative value, and the integral value is divided by 60 degrees (π / 3) to calculate the specific average voltage fluctuation over one rotation period of the electrical angle, Vppspave. Note that integral values ​​for other electrical angle ranges of 60 degrees (60 to 120 degrees, 120 to 180 degrees, 180 to 240 degrees, 240 to 300 degrees, 300 to 360 degrees) may also be calculated, and the integral value from 0 to 360 degrees may be calculated and divided by 360 degrees (2π).

[0092] Then, as shown in the second equation of the following equation, a specific average voltage fluctuation range Vppspave is divided by a specific voltage fluctuation range Vppsp of the current PWM period to calculate the ratio of the specific average voltage fluctuation range Vppspave to the specific voltage fluctuation range Vppsp, and the value obtained by multiplying this ratio by the target average setting time Tcave* is set as the setting time Tc of the PWM period.

number

[0093] By integrating the set frequency fc, which is the reciprocal of the PWM period setting time Tc, over the period T2π from 0 degrees to 360 degrees (the period of one rotation of the electrical angle), and substituting the reciprocal of the second equation of equation (14) and the first equation of equation (14), we obtain the following equation. As can be seen from the following equation, when the PWM period setting time Tc is set according to equation (14), the integral value of the PWM period setting frequency fc within one rotation of the electrical angle becomes equal to the value obtained by multiplying the reciprocal of the target average setting time Tcave* (target average setting frequency) by the period T2π from 0 degrees to 360 degrees. Therefore, the average number of switching cycles within one rotation of the electrical angle becomes equal to the average number of switching cycles when the target average setting time Tcave* is directly set as the PWM period setting time Tc. Furthermore, since the PWM period setting time Tc is set in proportion to the ratio of a specific average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp, as the current specific voltage fluctuation range Vppsp increases, the PWM period setting time Tc is reduced, thereby suppressing an increase in the actual voltage fluctuation range.

number

[0094] In the above, the setting time Tcsp of a specific PWM period is used for the calculation of Expression (12) for calculating a specific voltage fluctuation width Vppsp and a specific average voltage fluctuation width Vppspave. However, as can be seen from Expression (12), the specific average voltage fluctuation width Vppspave in the numerator of the second expression of Expression (14) is proportional to the setting time Tcsp of a specific PWM period, and the specific voltage fluctuation width Vppsp in the denominator of the second expression of Expression (14) is proportional to the setting time Tcsp of a specific PWM period. Therefore, the setting time Tcsp of the specific PWM period in the numerator and denominator of the second expression of Expression (14) is canceled out, and no matter what value is set for the setting time Tcsp of the specific PWM period, the calculation result of the ratio of the specific average voltage fluctuation width to the specific voltage fluctuation width in the second expression of Expression (14) is the same. Therefore, in the calculation of the ratio, any setting time may be used as the setting time Tcsp of the specific PWM period. For example, as the setting time Tcsp of the specific PWM period, the setting time Tc0 of a preset reference PWM period, or the target average setting time Tcave*, or the current setting time Tcnow of the current PWM period set by the current PWM period, or 1, or the capacitance C of the smoothing capacitor 2, or any value may be used. When the capacitance C is set, C in the denominator of Expression (12) can be canceled out.

[0095] <Configuration of PWM Period Setting Unit 34> Similar to the first embodiment, the PWM period setting unit 34 estimates the voltage fluctuation width Vpp, which is the voltage fluctuation width between the terminals of the smoothing capacitor 2 within one PWM period, and sets the setting time Tc of the subsequent PWM period based on the voltage fluctuation width Vpp.

[0096] In the present embodiment, assuming that a specific setting time Tcsp of a specific PWM period is set as the setting time Tc of the PWM period, the PWM period setting unit 34 estimates the ratio of the specific average voltage fluctuation width Vppspave within one electrical angle rotation period to the current specific voltage fluctuation width Vppsp, and sets the setting time Tc of the subsequent PWM period based on the ratio and the target average setting time Tcave* within one electrical angle rotation period.

[0097] With this configuration, the harmonic mean of the PWM period setting time Tc within one rotation period of the electrical angle (hereinafter referred to as the average setting time Tcave within one rotation period of the electrical angle) can be appropriately set based on the target average setting time Tcave*. Furthermore, the voltage fluctuation range Vpp can be appropriately changed based on the ratio of the average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp, assuming that a specific PWM period setting time Tcsp is set. If the average setting time Tcave within one rotation period of the electrical angle is the same, the average number of switching cycles of the switching element within one rotation period of the electrical angle will be the same, and the amount of heat generated by the switching element will also be approximately the same. Therefore, by appropriately setting the average setting time Tcave within one rotation period of the electrical angle based on the target average setting time Tcave*, the amount of heat generated by the switching element can be managed, the cooling mechanism of the power conversion circuit 1 can be appropriately designed, and the reliability of the power conversion circuit 1 can be improved.

[0098] The PWM period setting unit 34 sets the setting time Tc for the next and subsequent PWM periods by multiplying the ratio of the average voltage fluctuation range to the current specific voltage fluctuation range, assuming that a specific PWM period setting time Tcsp is set, by the target average setting time Tcave*.

[0099] With this configuration, the average setting time Tcave within one rotation period of the electrical angle can be matched to the target average setting time Tcave*, and as the current specific voltage fluctuation range increases relative to the specific average voltage fluctuation range assuming that a specific setting time Tcsp is set, the setting time Tc of the PWM period can be reduced, thereby suppressing an increase in the actual voltage fluctuation range. More specifically, the actual current specific voltage fluctuation range can be matched to the actual specific average voltage fluctuation range, thereby suppressing an increase in the actual voltage fluctuation range to the greatest extent possible. Here, since a dimensionless ratio of the setting time of the PWM period is used, the harmonic mean Tcave of the setting time Tc can be matched to the target average setting time Tcave*, while suppressing an increase in the actual voltage fluctuation range. If the average setting time Tcave within one rotation period of the electrical angle is the same, the average number of switching cycles of the switching element within one rotation period of the electrical angle will be the same, and the amount of heat generated by the switching element will also be approximately the same. Therefore, assuming that the average setting time Tcave matches the target average setting time Tcave*, the cooling mechanism of the power conversion circuit 1 can be designed, thereby improving the reliability of the power conversion circuit 1.

[0100] In this embodiment, the preset reference PWM period setting time Tc0 is used as the setting time Tcsp for a specific PWM period. Alternatively, the setting time Tcsp for a specific PWM period may be the target average setting time Tcave*, the current PWM period setting time Tcnow set for the current PWM period, 1, the capacitance C of the smoothing capacitor 2, or any arbitrary value.

[0101] In this embodiment, the PWM period setting unit 34 estimates a specific voltage fluctuation range Vppsp using the modulation rate M of the applied voltage to the three-phase armature windings, the current amplitude I of the three-phase current, the phase θ of the voltage command value of a specific phase, and the power factor angle ψ, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the current flowing through the armature winding of each phase.

[0102] In this embodiment, the PWM period setting unit 34 uses the modulation index M, the current amplitude I, the phase θ of the voltage command value of a specific phase, and the power factor angle ψ to estimate the ratio of a specific average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp, assuming that a specific PWM period setting time Tcsp is set.

[0103] As explained using equations (10) to (13), a specific voltage fluctuation range Vppsp can be calculated using the modulation index M, current amplitude I, phase θ of the voltage command value of a specific phase, power factor angle ψ, and the setting time Tcsp of a specific PWM period. Furthermore, by changing the phase θ of the voltage command value of a specific phase using not only the voltage fluctuation range Vppsp of the current PWM period, but also the modulation index M, current amplitude I, and power factor angle ψ, it is possible to estimate the change in a specific voltage fluctuation range Vppsp within one rotation period of the electrical angle, and calculate a specific average voltage fluctuation range Vppspave.

[0104] The PWM period setting unit 34 calculates the modulation rate M, current amplitude I, phase θ of the voltage command value of a specific phase, and power factor angle ψ based on the d-axis current command value id* and q-axis current command value iq* or the d-axis current detection value id and q-axis current detection value iq, the d-axis voltage command value vd* and q-axis voltage command value vq*, and the electrical angle θe.

[0105] Therefore, the PWM period setting unit 34 estimates the ratio of a specific average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp based on the d-axis current command value id* and the q-axis current command value iq* or the d-axis current detection value id and the q-axis current detection value iq, the d-axis voltage command value vd* and the q-axis voltage command value vq*, and the electrical angle θe.

[0106] As shown in Figure 7, in this embodiment, the PWM period setting unit 34 includes a voltage conversion unit 351, a current conversion unit 352, a power factor angle calculation unit 353, a voltage phase calculation unit 354, an average voltage fluctuation range calculation unit 355, a voltage fluctuation range calculation unit 356, and a PWM period calculation unit 357.

[0107] As shown in the following equation, the voltage conversion unit 351 calculates the RMS value Ve of the fundamental wave component of the applied voltage to the three-phase armature windings based on the voltage command value vd* on the d axis and the voltage command value vq* on the q axis, and calculates the modulation rate M by multiplying the ratio of the RMS value Ve of the three-phase applied voltage to the DC voltage Vpn by a coefficient (2√2 in this example). The voltage conversion unit 351 may also calculate the RMS value Ve of the three-phase applied voltage based on the three-phase voltage command values ​​vu*, vv*, and vw*. If harmonic components are superimposed on the three-phase voltage command values ​​vu*, vv*, and vw* due to overmodulation, the average value of the RMS value Ve over one period of the electrical angle is used. In this embodiment, a preset value is used for the DC voltage Vpn, but if the DC voltage Vpn is a variable system, a value detected by a voltage sensor may be used.

number

[0108] As shown in the following equation, the voltage conversion unit 351 calculates the phase θvdq of the voltage command value in the dq-axis coordinate system based on the voltage command value vd* of the d axis and the voltage command value vq* of the q axis. That is, the angle between the voltage command value vd* of the d axis and the voltage command value vq* of the q axis on the dq-axis coordinate system is determined by the four-quadrant arctangent. Here, the voltage command values ​​vd* and vq* of the d axis and q axis correspond to the fundamental wave (sine wave) component of the three-phase voltage command value, even when amplitude reduction modulation is performed, and the calculated phase θvdq of the voltage command value is also the phase of the fundamental wave component of the voltage command value with respect to the electrical angle θe.

number

[0109] As shown in the following equation, the current conversion unit 352 calculates the effective value Ie of the fundamental wave component of the three-phase current based on the current command value id* on the d axis and the current command value iq* on the q axis, and calculates the current amplitude I by multiplying the effective value Ie of the three-phase current by a coefficient (3 / √2 in this example). The current detection value id on the d axis and the current detection value iq on the q axis may also be used. The current conversion unit 352 may also calculate the effective value Ie of the three-phase current based on the current detection value id on the d axis and the current detection value iq on the q axis, or it may calculate the effective value Ie of the three-phase current based on the current detection values ​​iu, iv, and iw of the three phases. If harmonic components are superimposed on the current detection values ​​iu, iv, and iw of the three phases due to overmodulation, the average value of the effective value Ie over one period of the electrical angle is used.

number

[0110] As shown in the following equation, the current conversion unit 352 calculates the phase θidq of the current in the dq-axis coordinate system based on the current command value id* of the d axis and the current command value iq* of the q axis. That is, the angle of the current vector of the current command value id* of the d axis and the current command value iq* of the q axis on the dq-axis coordinate system is determined by the four-quadrant arctangent. Alternatively, the current detection value id of the d axis and the current detection value iq of the q axis may be used. Here, the current command values ​​id* and iq* of the d axis and q axis, or the current detection values ​​id and iq of the d axis and q axis, correspond to the fundamental wave (sine wave) component of the three-phase current, even when amplitude reduction modulation is performed, and the calculated current phase θidq is also the phase of the fundamental wave component of the current with respect to the electrical angle θe.

number

[0111] The power factor angle calculation unit 353 calculates the power factor angle ψ based on the phase θvdq of the voltage command value in the dq-axis coordinate system and the current phase θidq in the dq-axis coordinate system. Specifically, the power factor angle calculation unit 353 calculates the power factor angle ψ as the value obtained by subtracting the current phase θidq in the dq-axis coordinate system from the phase θvdq of the voltage command value in the dq-axis coordinate system, as shown in the following equation.

number

[0112] The voltage phase calculation unit 354 determines the phase θ of the voltage command value of a specific phase based on the phase θvdq of the voltage command value in the dq-axis coordinate system and the electrical angle θe of the rotor. Specifically, the voltage phase calculation unit 354 calculates the phase θ of the voltage command value of a specific phase by adding the phase θvdq of the voltage command value in the dq-axis coordinate system to the electrical angle θe of the rotor. The phase θ of the voltage command value of a specific phase is the phase (electrical angle) of the fundamental wave component of the voltage command value of the U phase with respect to the position of the armature winding of the U phase, and is the phase (electrical angle) such that the value obtained by multiplying the cosine of the phase θ of the voltage command value of the specific phase by the voltage amplitude becomes the fundamental wave component of the voltage command value of the U phase.

number

[0113] The average voltage fluctuation range calculation unit 355 calculates a specific average voltage fluctuation range Vppspave in one rotation period of the electrical angle, assuming that a specific PWM period setting time Tcsp is set as the PWM period setting time Tc, based on the modulation rate M, power factor angle ψ, and current amplitude I. Equation (14) 1 is used, and regardless of the current phase θ of the voltage command value of the specific phase, a range of 0 to 60 degrees (π / 3) is used as the phase θ of the voltage command value of the specific phase in Equation (14) 1. Equations (10) to (13) are used to calculate the specific voltage fluctuation range Vppsp in Equation (14) 1, and, similar to Equation (14) 1, a range of 0 to 60 degrees (π / 3) is used as the phase θ of the voltage command value of the specific phase in Equations (10) to (13), regardless of the current phase θ of the voltage command value of the specific phase. For example, the phase θ of the voltage command value of a specific phase may be increased by Δθ from 0 degrees to 60 degrees, and the operations in equations (10) to (13) may be performed for each θ, followed by the discrete integral operation of the first equation of equation (14). Alternatively, the phase θ of the voltage command value of the specific phase in the first equation of equation (14) and equations (10) to (13) may be set from 0 degrees to 360 degrees (2π), and the integral value may be divided by 2π; however, as mentioned above, the calculation result will be the same.

[0114] The voltage fluctuation range calculation unit 356 calculates a specific voltage fluctuation range Vppsp in the current PWM period based on the modulation rate M, the power factor angle ψ, the current amplitude I, and the phase θ of the voltage command value of the specific phase. Equations (10) to (13) are used, and the phase θ of the voltage command value of the current specific phase is used as the phase θ of the voltage command value of the specific phase in equations (10) to (13).

[0115] The PWM period calculation unit 357 calculates the PWM period setting time Tc based on the ratio of a specific average voltage fluctuation range Vppspave to a specific voltage fluctuation range Vppsp and the target average setting time Tcave* within one rotation period of the electrical angle. In this embodiment, as shown in the second equation of equation (14), the PWM period calculation unit 357 calculates the PWM period setting time Tc as a value obtained by multiplying the ratio of a specific average voltage fluctuation range Vppspave to a specific voltage fluctuation range Vppsp by the target average setting time Tcave*.

[0116] Similar to Embodiment 1, the calculated PWM period setting time Tc is reflected in the generation of the carrier wave cnt for subsequent PWM periods. In this embodiment, the PWM period setting unit 34 sets the PWM period setting time Tc for each PWM period after the three-phase voltage command values ​​vu*, vv*, and vw* have been calculated during the PWM period, and reflects this in the generation of the carrier wave cnt for the next PWM period. Alternatively, the PWM period setting unit 34 may set the PWM period setting time Tc for multiple (for example, two) PWM periods and reflect this in the generation of the carrier wave cnt for subsequent PWM periods until the next PWM period setting time Tc is set.

[0117] <Simplified configuration of the PWM period setting unit 34> As can be seen from equation (12), a specific voltage fluctuation range Vppsp is multiplied by the setting time Tcsp of a specific PWM period and the current amplitude I, and the specific average voltage fluctuation range Vppspave, which is the integral of the specific voltage fluctuation range Vppsp, is also multiplied by the setting time Tcsp of a specific PWM period and the current amplitude I. Therefore, when calculating the ratio of a specific average voltage fluctuation range Vppspave to a specific voltage fluctuation range Vppsp, the setting time Tcsp of a specific PWM period and the current amplitude I in the numerator and denominator cancel each other out.

[0118] Therefore, in the calculation of a specific voltage fluctuation range Vppsp and a specific average voltage fluctuation range Vppspave, the ratio calculation result will be the same even if one or both of the setting time Tcsp and current amplitude I of a specific PWM period are replaced with a fixed value (1 in this example). In other words, by replacing one or both of the setting time Tcsp and current amplitude I of a specific PWM period with a fixed value (1 in this example), the setting or calculation of the parameter to be replaced can be omitted.

[0119] Specifically, the current amplitude I in equation (12) is replaced with a fixed value (1 in this example), and the calculation of the current amplitude I in the current conversion unit 352 is omitted. The setting time Tcsp for a specific PWM period in equation (12) is replaced with a fixed value (for example, 1). Both the setting time Tcsp for a specific PWM period and the current amplitude I may be replaced with a fixed value (1), or either one may be replaced with a fixed value (1). Furthermore, if the current amplitude I or the setting time Tcsp for a specific PWM period is replaced with the capacitance C of the smoothing capacitor 2, as described above, the C in the denominator of equation (12) can be canceled, further simplifying the calculation. Thus, the specific voltage fluctuation width Vppsp and the specific average voltage fluctuation width Vppspave, whose calculations have been simplified in this way, are also referred to as the specific voltage fluctuation width Vppsp and the specific average voltage fluctuation width Vppspave for convenience of explanation. Furthermore, if the setting time Tcsp for a specific PWM period is replaced with a fixed value (1 or C), the fixed value (1 or C) is the setting time Tcsp for that specific PWM period.

[0120] Even when the current amplitude I is replaced with a fixed value (1) and the calculation is omitted, the calculation of the modulation rate M and the phase θ and power factor angle ψ of the voltage command value of a specific phase used in equation (12) requires the current command values ​​id*, iq* or current detection values ​​id, iq for the d and q axes, the voltage command values ​​vd*, vq* for the d and q axes, and the electrical angle θe. Therefore, as in the case where it is not simplified, the PWM period setting unit 34 estimates the ratio of a specific average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp based on the current command values ​​id*, iq* or current detection values ​​id, iq for the d and q axes, the voltage command values ​​vd*, vq* for the d and q axes, and the electrical angle θe. Furthermore, the PWM period setting unit 34 uses the modulation index M, the phase θ of the voltage command value of a specific phase, and the power factor angle ψ to calculate a simplified current specific voltage fluctuation range Vppsp and a simplified specific average voltage fluctuation range Vppspave, and calculates the ratio of the simplified specific average voltage fluctuation range Vppspave to the simplified current specific voltage fluctuation range Vppsp. The result of the ratio calculation is the same as the result of the ratio calculation when the system is not simplified. The simplification described above can also be applied in the case of various amplitude reduction modulations described below.

[0121] <When pseudo-third harmonic superposition is performed> The above describes the case where amplitude reduction modulation is not performed and the three-phase voltage command values ​​vu*, vv*, and vw* used in PWM control are sinusoidal. Below, we will explain the calculation formulas for the voltage fluctuation range Vpp when various types of amplitude reduction modulation are performed.

[0122] First, let's explain pseudo-third harmonic superposition. In pseudo-third harmonic superposition, the average of the maximum and minimum values ​​of the three-phase voltage command values ​​before amplitude reduction modulation is calculated, and this average value (offset voltage) is subtracted from each of the three-phase voltage command values ​​to calculate the modulated three-phase voltage command values, which are used for PWM control. The average value (offset voltage) is a triangular wave with a rotation period three times that of the electrical angle.

[0123] In this case, the aforementioned pseudo-third harmonic superposition occurs, so equation (12) is changed to equation (22). Here, similar to equation (12), MOD(θ, π / 3) is a function that outputs the remainder when the phase θ of the voltage command value of a specific phase is divided by π / 3, and the remainder is set as θ'.

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[0124] Furthermore, when this pseudo-third harmonic superposition (or substantially equivalent symmetric space vector modulation) is used, the voltage fluctuation range calculation unit 356 can be further simplified due to its symmetry.

[0125] As shown in equation (22), the absolute value of V1 and the absolute value of V3 are equal. Therefore, one of V1 or V3 can be omitted. Furthermore, even without calculating both V1 and V2, it is possible to determine which absolute value is larger with a simple check. For example, by comparing the signs of idc and idc+i1, if they have the same sign, the absolute value of V2 is greater than the absolute value of V1, so only V2 needs to be calculated. If they have different signs, the absolute value of V1 is greater than the absolute value of V2, so only V1 needs to be calculated.

[0126] <When two-phase modulation is performed> In two-phase modulation, an offset voltage is added to each of the three pre-modulation voltage command values ​​such that the lowest voltage command value matches the lower voltage side of the DC voltage (in this example, -Vpn / 2). Alternatively, an offset voltage is added to each of the three pre-modulation voltage command values ​​such that the highest voltage command value matches the higher voltage side of the DC voltage (in this example, +Vpn / 2). In two-phase modulation, switching of the lowest or highest voltage phase is stopped, thus reducing the number of switching cycles.

[0127] In two-phase modulation, there are various methods for determining which phase switching to stop. Here, we illustrate the calculation for a method where the switching is stopped evenly across a 60-degree range before and after the phase with the maximum or minimum voltage of each phase. Equation (12) is changed to equation (23). MOD(θ+π / 3,π / 3)-π / 3 is a function that outputs the remainder when the phase θ+π / 3 of the voltage command value of a specific phase is divided by π / 3, and the remainder -π / 3 is set as θ'. For example, if θ is from -30 degrees to +30 degrees, θ' is set to -30 degrees to +30 degrees. Similarly, if θ is from 30 degrees to 90 degrees, θ' is set to -30 degrees to +30 degrees, and if θ is from 90 degrees to 150 degrees, θ' is set to -30 degrees to +30 degrees. More precisely, within each 60-degree range, |V1| and |V3| on the right-hand side of equation (23) are swapped, but since a specific voltage fluctuation range Vppsp is calculated using the maximum values ​​of |V1|, |V2|, and |V3|, the specific voltage fluctuation range Vppsp is calculated correctly.

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[0128] 3. Embodiment 3 The control device 30 and AC rotating electric machine 103 according to Embodiment 3 will now be described. The same components as in Embodiments 1 and 2 described above will be omitted from the description. The basic configuration of the control device 30 and AC rotating electric machine 103 according to this embodiment is the same as in Embodiment 1, however, in this embodiment, the rotor is not provided with permanent magnets, the AC rotating electric machine 103 is an induction rotating electric machine, and the control device 30 performs V / f control.

[0129] Figure 8 is a system configuration diagram showing a DC power supply 102, a power conversion circuit 1 having a smoothing capacitor 2, an AC rotating electric machine 103, and a control device 30 according to this embodiment. In this embodiment, the control device 30 performs V / f control and applies voltage to the armature winding. Therefore, current feedback control is not performed, and a current sensor 4 is not provided. Also, an angle sensor 5 is not provided. Furthermore, the AC rotating electric machine 103 is intended for applications where the load torque is determined almost uniquely according to the rotation speed (for example, a blower fan).

[0130] As shown in Figure 9, the control device 30 includes an output control unit 33 and a PWM period setting unit 34.

[0131] The output control unit 33 calculates the three-phase voltage command values ​​vu*, vv*, and vw* to be applied to the three-phase armature windings, and controls the on / off state of the multiple switching elements of the power conversion circuit 1 using PWM control based on the three-phase voltage command values ​​vu*, vv*, and vw*.

[0132] In this embodiment, the output control unit 33 includes a phase voltage command value calculation unit 336 and a PWM control unit 335. The configuration of the PWM control unit 335 is the same as in Embodiment 1, so its description is omitted.

[0133] The phase voltage command value calculation unit 336 calculates the three phase voltage command values ​​vu*, vv*, and vw* based on the voltage amplitude command value V* and the speed command value ωe*. Specifically, as shown in equation (24), the phase voltage command value calculation unit 336 integrates the speed command value ωe* to calculate the phase θ of the voltage command value of a specific phase (in this example, the U phase), and as shown in equation (25), calculates the three phase voltage command values ​​vu*, vv*, and vw* based on the phase θ of the voltage command value of the specific phase and the voltage amplitude command value V*. Amplitude reduction modulation may be applied to the three phase voltage command values ​​vu*, vv*, and vw*.

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[0134] The PWM period setting unit 34 estimates the voltage fluctuation range Vpp, which is the fluctuation range of the terminal voltage of the smoothing capacitor 2 within one PWM period, and sets the setting time Tc for the next PWM period based on the voltage fluctuation range Vpp.

[0135] Similar to Embodiment 2, the PWM period setting unit 34 estimates the ratio of a specific average voltage fluctuation range Vppspave within one rotation period of the electrical angle to the current specific voltage fluctuation range Vppsp, assuming that a specific PWM period setting time Tcsp is set as the PWM period setting time Tc, and sets the setting time Tc for the next and subsequent PWM periods based on the ratio and the target average setting time Tcave* within one rotation period of the electrical angle.

[0136] Similar to Embodiment 2, the PWM period setting unit 34 sets the value obtained by multiplying the ratio by the target average setting time Tcave* as the setting time Tc for the next PWM period.

[0137] In this embodiment, the PWM period setting unit 34 estimates the ratio of a specific average voltage fluctuation range Vppspave to the current specific voltage fluctuation range Vppsp using the modulation rate M of the applied voltage to the three-phase armature windings, the phase θ of the voltage command value of a specific phase, and the power factor angle ψ, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the current flowing through the armature winding of each phase.

[0138] As described in Embodiment 2, when calculating the ratio of a specific average voltage fluctuation range Vppspave to a specific voltage fluctuation range Vppsp, the current amplitude I included in the numerator and denominator is canceled out, thus simplifying the calculation of the current amplitude I. Therefore, the ratio can be calculated even in a control system that does not control the current, as in this embodiment.

[0139] As shown in Figure 10, the PWM period setting unit 34 includes a voltage conversion unit 351, a power factor angle calculation unit 353, an average voltage fluctuation range calculation unit 355, a voltage fluctuation range calculation unit 356, and a PWM period calculation unit 357. The PWM period calculation unit 357 is configured in the same way as in Embodiment 2, so its description is omitted.

[0140] As shown in the following equation, the voltage conversion unit 351 calculates the effective value Ve of the three-phase applied voltages based on the voltage amplitude command value V*. As in Embodiment 2, the effective value Ve may be calculated based on the three-phase voltage command value. The voltage conversion unit 351 calculates the modulation rate M by multiplying the ratio of the effective value Ve of the three-phase applied voltages to the DC voltage Vpn by a coefficient (2√2 in this example).

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[0141] The power factor angle calculation unit 353 calculates the power factor angle ψ corresponding to the current voltage amplitude command value V* by referring to a characteristic function whose relationship with the voltage amplitude command value V* is predetermined. Map data or a higher-order function (e.g., a polynomial) is used as the characteristic function.

[0142] In the calculations for the specific voltage fluctuation range Vppsp and the specific average voltage fluctuation range Vppspave in Embodiment 2, the current amplitude I is replaced with a fixed value (e.g., 1), and the current amplitude I is omitted, so a detailed explanation of the average voltage fluctuation range calculation unit 355 and the voltage fluctuation range calculation unit 356 is omitted. Alternatively, the setting time Tcsp for the specific PWM period may be set to 1 or C.

[0143] Even when V / f control is performed as in this embodiment, the same effects as in Embodiment 2 can be obtained.

[0144] [Other embodiments] (1) In Embodiment 1, similar to Embodiment 2, the PWM period setting unit 34 may estimate a specific voltage fluctuation range Vppsp using the modulation index M, the current amplitude I, the phase θ of the voltage command value of a specific phase, and the power factor angle ψ.

[0145] (2) The AC rotating electric machine 103 may be an induction motor or a synchronous reluctance motor in which permanent magnets are not provided on the rotor 8. In this case as well, a specific voltage fluctuation range Vppsp can be estimated using the three-phase voltage command values ​​and three-phase current detection values, and the PWM period setting time Tc can be set, similar to Embodiment 1. Furthermore, whether current control is performed in the dq-axis coordinate system or not, by converting the three-phase voltages and currents to the currents and currents of the dq-axis coordinate system, the ratio of a specific average voltage fluctuation range Vppspave to a specific voltage fluctuation range Vppsp can be estimated using the dq-axis currents and voltages, similar to Embodiment 2, and the WM period setting time Tc can be set.

[0146] (3) In each of the above embodiments, the PWM period setting time Tc was set. However, instead of the PWM period setting time Tc, the PWM period setting frequency fc may be set. In this case, instead of the PWM period setting time Tc and the setting time Tcsp for a specific PWM period, the setting frequency fc for 1 / PWM period and the setting frequency fcsp for 1 / specific PWM period may be used.

[0147] (4) In the above embodiments, the example described was that one set of three-phase armature windings and power conversion circuits 1 is provided, and the control device 30 is configured to match this one set. However, two or more sets of three-phase armature windings and power conversion circuits 1 may be provided. In this case, the control device 30 performs the same control for each set as in the above embodiments. The control device 30 estimates the voltage fluctuation range of each set and sets the PWM period setting time Tc for each set based on the voltage fluctuation range of each set.

[0148] <Summary of the various aspects of this disclosure> The various aspects of this disclosure are summarized below as an appendix. (Note 1) A control device for an AC rotating electric machine having multiple phase armature windings, which controls the AC rotating electric machine via a power conversion circuit connected to a DC power supply and having a smoothing capacitor connected in parallel to the DC power supply, An output control unit calculates multi-phase voltage command values ​​to be applied to the multi-phase armature windings, and controls the on / off state of multiple switching elements in the power conversion circuit by PWM control based on the multi-phase voltage command values, A PWM period setting unit estimates the voltage fluctuation range, which is the voltage fluctuation range across the terminals of the smoothing capacitor within one cycle of the PWM control, and sets the setting time for the next and subsequent PWM control cycles based on the voltage fluctuation range. A control device for an AC rotating electric machine equipped with the following features.

[0149] (Note 2) The PWM period setting unit estimates a specific voltage fluctuation range assuming that a specific setting time is set as the setting time, A control device for an AC rotating electric machine as described in Appendix 1, wherein the set time is reduced as the estimated specific voltage fluctuation range increases.

[0150] (Note 3) The PWM period setting unit estimates a specific voltage fluctuation range assuming that a specific setting time is set as the setting time, A control device for an AC rotating electric machine according to Appendix 1 or 2, which sets the setting time based on the estimated specific voltage fluctuation range, the target voltage fluctuation range, and the specific setting time.

[0151] (Note 4) The control device for an AC rotating electric machine as described in Appendix 3, wherein the PWM period setting unit sets the setting time to a value obtained by multiplying the ratio of the target voltage fluctuation range to the estimated specific voltage fluctuation range by the specific setting time.

[0152] (Note 5) The control device for an AC rotating electric machine according to any one of the appendices 2 to 4, wherein the PWM period setting unit estimates the specific voltage fluctuation range using the duty cycle of the PWM control for the multiple phases corresponding to each of the voltage command values ​​of the multiple phases and the current flowing through the armature windings of the multiple phases.

[0153] (Note 6) The PWM period setting unit assigns sequential numbers to the duty cycles of the PWM control for each of the multiple phases corresponding to the voltage command values ​​of the multiple phases, starting from the phase with the smallest duty cycle. A control device for an AC rotating electric machine according to any one of the appendices 2 to 5, which estimates the specific voltage fluctuation range using the duty cycles of multiple phases assigned sequential numbers and the currents flowing through the armature windings of the multiple phases assigned sequential numbers.

[0154] (Note 7) The control device for an AC rotating electric machine according to Appendix 1 or 2, wherein the PWM period setting unit estimates the ratio of the average value of the specific voltage fluctuation range within one rotation period of the electric angle to the current specific voltage fluctuation range, assuming that a specific setting time is set as the setting time, and sets the setting time based on the ratio and the target average setting time within one rotation period of the electric angle.

[0155] (Note 8) The control device for an AC rotating electric machine as described in Appendix 7, wherein the PWM period setting unit sets the setting time to a value obtained by multiplying the ratio by the target average setting time.

[0156] (Note 9) The output control unit calculates the current command value of the d axis and the current command value of the q axis, converts the detected current values ​​flowing through the multi-phase armature windings into the detected current values ​​of the d axis and the q axis based on the electrical angle of the rotor of the AC rotating electric machine, calculates the voltage command value of the d axis and the voltage command value of the q axis such that the detected current value of the d axis approaches the current command value of the d axis and the detected current value of the q axis approaches the current command value of the q axis, and converts the voltage command value of the d axis and the voltage command value of the q axis into the multi-phase voltage command values ​​based on the electrical angle. A control device for an AC rotating electric machine according to any one of the appendices 2 to 4, 7, and 8, wherein the PWM period setting unit estimates the specific voltage fluctuation range based on the current command value of the d axis and the current command value of the q axis or the current detection value of the d axis and the current detection value of the q axis, the voltage command value of the d axis and the voltage command value of the q axis, and the electrical angle.

[0157] (Note 10) A control device for an AC rotating electric machine according to any one of the appendices 2 to 4, 7, and 8, wherein the PWM period setting unit estimates the specific voltage fluctuation range using the modulation rate of the applied voltage to the multiple phase armature windings, the current amplitude of the current flowing through the multiple phase armature windings, the phase of the voltage command value of a specific phase, and the power factor angle, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the current flowing through the armature winding of each phase.

[0158] (Note 11) The output control unit calculates the current command value of the d axis and the current command value of the q axis, converts the detected current values ​​flowing through the multi-phase armature windings into the detected current values ​​of the d axis and the q axis based on the electrical angle of the rotor of the AC rotating electric machine, calculates the voltage command value of the d axis and the voltage command value of the q axis such that the detected current value of the d axis approaches the current command value of the d axis and the detected current value of the q axis approaches the current command value of the q axis, and converts the voltage command value of the d axis and the voltage command value of the q axis into the multi-phase voltage command values ​​based on the electrical angle. The control device for an AC rotating electric machine as described in Appendix 10, wherein the PWM period setting unit calculates the modulation rate, the current amplitude, the phase of the voltage command value, and the power factor angle based on the current command value of the d axis and the current command value of the q axis or the current detection value of the d axis and the current detection value of the q axis, the voltage command value of the d axis and the voltage command value of the q axis, and the electrical angle.

[0159] (Note 12) The control device for an AC rotating electric machine as described in Appendix 7 or 8, wherein the PWM period setting unit estimates the ratio using the modulation rate of the applied voltages to the multiple phase armature windings, the phase of the voltage command value of a specific phase, and the power factor angle, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the current flowing through the armature winding of each phase.

[0160] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed in this disclosure. For example, these include modifying, adding or omitting at least one component, or even extracting at least one component and combining it with a component from another embodiment. [Explanation of Symbols]

[0161] 1: Power conversion circuit, 2: Smoothing capacitor, 7: Armature, 8: Rotor, 30: Control device for AC rotating electric machine, 33: Output control unit, 34: PWM period setting unit, 103: AC rotating electric machine, I: Current amplitude, M: Modulation rate, Tc: PWM period setting time, Tcave*: Target average setting time, Tcsp: Specific PWM period setting time, Vpp: Voltage fluctuation range, Vppsp: Specific voltage fluctuation range, Vppspave: Specific average voltage fluctuation range, id*: Current command value on the d axis, iq*: Current command value on the q axis, id: Current detection value on the d axis, iq: Current detection value on the q axis, idc: DC current, vd*: Voltage command value on the d axis, vq*: Voltage command value on the q axis, θ: Phase of the voltage command value of a specific phase, θe: Electrical angle, ψ: Power factor angle

Claims

1. A control device for an AC rotating electric machine having multiple phase armature windings, which controls the AC rotating electric machine via a power conversion circuit connected to a DC power supply and having a smoothing capacitor connected in parallel to the DC power supply, An output control unit calculates multi-phase voltage command values ​​to be applied to the multi-phase armature windings, and controls the on / off state of multiple switching elements in the power conversion circuit by PWM control based on the multi-phase voltage command values, A PWM period setting unit estimates the voltage fluctuation range, which is the voltage fluctuation range between the terminals of the smoothing capacitor within one cycle of the PWM control, and sets the setting time for the next and subsequent PWM control cycles based on the voltage fluctuation range. A control device for an AC rotating electric machine equipped with the following features.

2. The PWM period setting unit estimates a specific voltage fluctuation range assuming that a specific setting time is set as the setting time, A control device for an AC rotating electric machine according to claim 1, wherein the set time is reduced as the estimated specific voltage fluctuation range increases.

3. The PWM period setting unit estimates a specific voltage fluctuation range assuming that a specific setting time is set as the setting time, A control device for an AC rotating electric machine according to claim 1, wherein the set time is set based on the estimated specific voltage fluctuation range, the target voltage fluctuation range, and the specific set time.

4. The control device for an AC rotating electric machine according to claim 3, wherein the PWM period setting unit sets the setting time to a value obtained by multiplying the ratio of the target voltage fluctuation range to the estimated specific voltage fluctuation range by the specific setting time.

5. The control device for an AC rotating electric machine according to claim 2, wherein the PWM period setting unit estimates the specific voltage fluctuation range using the duty cycle of the PWM control for each of the multiple phases corresponding to the voltage command values ​​of each of the multiple phases and the currents flowing through the armature windings of the multiple phases.

6. The PWM period setting unit assigns sequential numbers to the duty cycles of the PWM control for each of the multiple phases corresponding to the voltage command values ​​of the multiple phases, starting from the phase with the smallest duty cycle. A control device for an AC rotating electric machine according to claim 2, which estimates the specific voltage fluctuation range using the duty cycles of multiple phases assigned sequential numbers and the currents flowing through the armature windings of the multiple phases assigned sequential numbers.

7. The control device for an AC rotating electric machine according to claim 1, wherein the PWM period setting unit estimates the ratio of the average value of the specific voltage fluctuation range within one rotation period of the electrical angle to the current specific voltage fluctuation range, assuming that a specific setting time is set as the setting time, and sets the setting time based on the ratio and the target average setting time within one rotation period of the electrical angle.

8. The control device for an AC rotating electric machine according to claim 7, wherein the PWM period setting unit sets the setting time to a value obtained by multiplying the ratio by the target average setting time.

9. The output control unit calculates the current command value of the d axis and the current command value of the q axis, converts the detected current values ​​flowing through the multi-phase armature windings into the detected current values ​​of the d axis and the q axis based on the electrical angle of the rotor of the AC rotating electric machine, calculates the voltage command value of the d axis and the voltage command value of the q axis such that the detected current value of the d axis approaches the current command value of the d axis and the detected current value of the q axis approaches the current command value of the q axis, and converts the voltage command value of the d axis and the voltage command value of the q axis into the multi-phase voltage command values ​​based on the electrical angle. The control device for an AC rotating electric machine according to any one of claims 2 to 4, 7, and 8, wherein the PWM period setting unit estimates the specific voltage fluctuation range based on the current command value of the d axis and the current command value of the q axis or the current detection value of the d axis and the current detection value of the q axis, the voltage command value of the d axis and the voltage command value of the q axis, and the electrical angle.

10. A control device for an AC rotating electric machine according to any one of claims 2 to 4, 7, and 8, wherein the PWM period setting unit estimates the specific voltage fluctuation range using the modulation rate of the applied voltages to the multiple phase armature windings, the current amplitude of the currents flowing through the multiple phase armature windings, the phase of the voltage command value of a specific phase, and the power factor angle, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the currents flowing through the armature windings of each phase.

11. The output control unit calculates the current command value of the d axis and the current command value of the q axis, converts the detected current values ​​flowing through the multi-phase armature windings into the detected current values ​​of the d axis and the q axis based on the electrical angle of the rotor of the AC rotating electric machine, calculates the voltage command value of the d axis and the voltage command value of the q axis such that the detected current value of the d axis approaches the current command value of the d axis and the detected current value of the q axis approaches the current command value of the q axis, and converts the voltage command value of the d axis and the voltage command value of the q axis into the multi-phase voltage command values ​​based on the electrical angle. The control device for an AC rotating electric machine according to claim 10, wherein the PWM period setting unit calculates the modulation rate, the current amplitude, the phase of the voltage command value, and the power factor angle based on the current command value of the d axis and the current command value of the q axis or the current detection value of the d axis and the current detection value of the q axis, the voltage command value of the d axis and the voltage command value of the q axis, and the electrical angle.

12. The control device for an AC rotating electric machine according to claim 7 or 8, wherein the PWM period setting unit estimates the ratio using the modulation rate of the applied voltages to the multiple phase armature windings, the phase of the voltage command value of a specific phase, and the power factor angle, which is the phase difference between the phase of the fundamental wave of the voltage command value of each phase and the phase of the fundamental wave of the current flowing through the armature winding of each phase.

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