AC rotating electric machine control device

Abstract

To provide a controller for an AC rotary electric machine which can suppress a low frequency component of a current generated at a specific carrier signal number.SOLUTION: The controller for an AC rotary electric machine changes at least one of a carrier frequency and an update frequency so that an evaluation value operated based on a carrier signal number as a value obtained by dividing the AC frequency of an AC voltage instruction value by a carrier frequency and an update frequency does not match with a specific value where a component of a frequency lower than the AC cycle increases for at least one of currents, voltages, and powers supplied to a plurality of windings.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Control devices for AC rotating electric machines use PWM (Pulse Width Modulation) control to turn the inverter's switching elements on and off. A control method that reduces inverter losses is desired. The losses that occur in inverters are divided into switching loss and conduction loss. Switching loss occurs when the switching elements are turned on and off, while conduction loss occurs when current flows through the switching elements. Switching loss can be reduced by lowering the carrier frequency of PWM control and reducing the number of times the switching elements are turned on and off. However, lowering the carrier frequency too much can make the control unstable.

[0003] In order to ensure control stability while reducing switching loss, for example, in Patent Document 1, when the carrier signal number, which is the frequency of the carrier signal during an AC cycle, decreases, the mode is switched to a synchronous PWM mode in which the carrier frequency is set to a natural number multiple of the AC frequency.

[0004] In Patent Document 2, control is performed to prevent the frequency at which electromagnetic noise resulting from the switching frequency becomes maximum depending on the power supply angular frequency from exceeding a predetermined value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4205157 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-198342 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors have confirmed that when the inverter is controlled to an overmodulation state in which the oscillation range of the AC voltage command value exceeds the oscillation range of the carrier signal and the control is performed with a low carrier signal number in order to improve the inverter output and reduce switching loss, low-frequency components increase in one or more of the current, voltage, and power at a specific carrier signal number. However, Patent Documents 1 and 2 do not disclose a solution to this phenomenon.

[0007] Therefore, an object of the present application is to provide a control device for an AC rotating electric machine that can suppress low frequency components of currents and the like that occur at a specific number of carrier signals. [Means for solving the problem]

[0008] A control device for an AC rotating electric machine according to the present application is a control device for an AC rotating electric machine that controls an AC rotating electric machine having a plurality of phase windings via an inverter, a voltage command calculation unit that calculates and updates AC voltage command values ​​for multiple phases to be applied to the windings of the multiple phases in an update period; a PWM control unit that generates a carrier signal that has an amplitude according to the DC voltage supplied to the inverter and oscillates with a carrier period, and controls on / off of a plurality of switching elements included in the inverter based on a comparison result between each of the AC voltage command values ​​of the plurality of phases and the carrier signal; a period changing unit that changes one or both of the carrier period and the update period; Equipped with The period changing unit changes one or both of the carrier period and the update period so that an evaluation value calculated based on the update period and the number of carrier signals, which is a value obtained by dividing the AC period of the AC voltage command value by the carrier period, does not match a specific value at which components of frequencies lower than the AC period increase for one or more of the current, voltage, and power supplied to the plurality of windings. [Effects of the Invention]

[0009] According to the control device for an AC rotating electric machine of the present application, when the evaluation value calculated based on the number of carrier signals and the update period matches a specific value, low-frequency components increase. Therefore, by changing one or both of the carrier period and the update period so that the evaluation value does not match a specific value, it is possible to suppress the increase in low-frequency components such as current. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of an AC rotating electric machine and a control device for the AC rotating electric machine according to a first embodiment. [Figure 2] 1 is a schematic block diagram of a control device for an AC rotating electric machine according to a first embodiment. [Figure 3] 1 is a hardware configuration diagram of a control device for an AC rotating electric machine according to a first embodiment. [Figure 4] 6 is a time chart illustrating a control behavior according to a comparative example of the first embodiment. [Figure 5] 10 is a time chart illustrating a control behavior in the case where P=11 and n=1 according to a comparative example of the first embodiment. [Figure 6] 10 is a time chart illustrating a control behavior in a comparative example of the first embodiment when P=11 and n=2. [Figure 7] 10 is a diagram illustrating the magnitude of the offset component of the phase current with respect to the change in the number P of carrier signals when n=1 and n=2 according to a comparative example of the first embodiment. FIG. [Figure 8] 10 is a time chart illustrating a control behavior in a comparative example of the first embodiment when N=5 and n=1. [Figure 9] 10 is a time chart illustrating a control behavior in a comparative example of the first embodiment when N=10 and n=2. [Figure 10] FIG. 10 is a diagram illustrating the magnitude of 1 / N with respect to a change in the number P of carrier signals when n=1 according to a comparative example of the first embodiment. [Figure 11] 10 is a time chart illustrating a control behavior in an overmodulation state according to a comparative example of the first embodiment, where N=7 and n=1. [Figure 12]10 is a time chart illustrating a control behavior in a normal modulation state when N=7 and n=1 according to a comparative example of the first embodiment. [Figure 13] 4A and 4B are diagrams illustrating an overmodulation state region and a normal modulation state region according to the first embodiment. [Figure 14] FIG. 4 is a diagram illustrating setting of a carrier period based on an AC period according to the first embodiment. [Figure 15] FIG. 4 is a diagram illustrating setting of a carrier period based on an AC period according to the first embodiment. [Figure 16] FIG. 4 is a diagram illustrating random setting of a carrier period according to the first embodiment. [Figure 17] FIG. 4 is a diagram illustrating setting of an update period based on an AC period according to the first embodiment. [Figure 18] FIG. 4 is a diagram illustrating setting of an update period based on an AC period according to the first embodiment. [Figure 19] 5 is a diagram illustrating setting of a carrier cycle when a synchronous PWM mode is executed according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1. First Embodiment A control device 1 for an AC rotating electric machine according to a first embodiment (hereinafter simply referred to as the control device 1) will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of an AC rotating electric machine 5 and the control device 1 according to the present embodiment.

[0012] 1-1.AC rotating electric machine The AC rotating electric machine 5 has multi-phase windings. The AC rotating electric machine 5 has a stator and a rotor, and the multi-phase windings are provided on the stator. In this embodiment, three-phase windings Cu, Cv, and Cw, i.e., U-phase, V-phase, and W-phase, are provided. The three-phase windings Cu, Cv, and Cw are star-connected. The three-phase windings may also be delta-connected. The AC rotating electric machine 5 is a permanent magnet-type synchronous rotating electric machine in which a permanent magnet is provided on the rotor. For example, a rare earth magnet such as neodymium or samarium cobalt is used as the permanent magnet, but various types of permanent magnets such as inexpensive ferrite magnets may also be used. The AC rotating electric machine 5 may also be a field-winding-type synchronous rotating machine in which a field winding is provided on the rotor. Alternatively, the AC rotating electric machine 5 may be an induction rotating machine in which a cage-type electrical conductor is provided on the rotor.

[0013] The AC rotating electric machine 5 is equipped with a rotation sensor 6 that outputs an electric signal corresponding to the rotation angle of the rotor. The rotation sensor 6 is a Hall element, an encoder, a resolver, or the like. The output signal of the rotation sensor 6 is input to the control device 1.

[0014] 1-2.Inverter The inverter 20 is a power converter that performs power conversion between the DC power supply 10 and the three-phase windings, and includes a plurality of switching elements. The inverter 20 includes three sets of series circuits (legs) corresponding to the three phase windings, each set including a high-potential-side switching element 23H (upper arm) connected to the high-potential side of the DC power supply 10 and a low-potential-side switching element 23L (lower arm) connected to the low-potential side of the DC power supply 10. The inverter 20 includes a total of six switching elements: three high-potential-side switching elements 23H and three low-potential-side switching elements 23L. The connection point where the high-potential-side switching element 23H and the low-potential-side switching element 23L are connected in series is connected to the winding of the corresponding phase.

[0015] Specifically, in the series circuit of each phase, the collector terminal of high-potential side switching element 23H is connected to high-potential side wire 24, the emitter terminal of high-potential side switching element 23H is connected to the collector terminal of low-potential side switching element 23L, and the emitter terminal of low-potential side switching element 23L is connected to low-potential side wire 25. The connection point between high-potential side switching element 23H and low-potential side switching element 23L is connected to the winding of the corresponding phase.

[0016] The switching elements may be IGBTs (Insulated Gate Bipolar Transistors) connected in anti-parallel to diodes 22, or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) that function as anti-parallel connected diodes. The gate terminals of the switching elements are connected to the control device 1. The control device 1 outputs a control signal to turn the switching elements on or off.

[0017] A smoothing capacitor 26 is connected between the high-potential side electric wire 24 and the low-potential side electric wire 25. A voltage sensor 27 is provided to detect the DC voltage VDC supplied from the DC power supply 10 to the inverter 20. The voltage sensor 27 is connected between the high-potential side electric wire 24 and the low-potential side electric wire 25. An output signal of the voltage sensor 27 is input to the control device 1.

[0018] Current sensor 28 outputs an electrical signal corresponding to the current flowing through the winding of each phase. Current sensor 28 is provided on the electric wire of each phase connecting the series circuit of the switching elements to the winding. The output signal of current sensor 28 is input to control device 1. Note that current sensor 28 may also be provided in the series circuit of each phase.

[0019] The DC power supply 10 outputs a DC voltage VDC to the inverter 20. The DC power supply 10 may be any device that outputs a DC voltage VDC, such as a battery, a DC-DC converter, a diode rectifier, or a PWM rectifier.

[0020] 1-3.Control device The control device 1 controls the AC rotating electric machine 5 via the inverter 20. As shown in Fig. 2, the control device 1 includes a rotation detection unit 31, a voltage command calculation unit 32, a PWM control unit 33, and a period change unit 34. Each function of the control device 1 is realized by a processing circuit included in the control device 1. Specifically, as shown in Fig. 3, the control device 1 includes, as processing circuits, an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 that exchanges data with the arithmetic processing device 90, an input circuit 92 that inputs external signals to the arithmetic processing device 90, and an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside.

[0021] The arithmetic processing device 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, various signal processing circuits, etc. Furthermore, the arithmetic processing device 90 may include a plurality of the same or different types of devices, each performing a different process. The storage device 91 may include a RAM (Random Access Memory) configured to be able to read and write data from the arithmetic processing device 90, and a ROM (Read Only Memory) configured to be able to read data from the arithmetic processing device 90. The input circuit 92 is connected to various sensors and switches, such as the voltage sensor 27, the current sensor 28, and the rotation sensor 6, and includes an A / D converter and the like that inputs output signals from these sensors and switches to the arithmetic processing device 90. The output circuit 93 is connected to electrical loads, such as a gate drive circuit that drives switching elements on and off, and includes a drive circuit and the like that outputs control signals from the arithmetic processing device 90 to these electrical loads.

[0022] 2 provided in the control device 1 are realized by an arithmetic processing device 90 executing software (programs) stored in a storage device 91 such as a ROM, and cooperating with other hardware of the control device 1 such as the storage device 91, an input circuit 92, and an output circuit 93. Setting data such as the carrier period Tca and the update period Tup used by the control devices 31 to 34 is stored in the storage device 91 such as a ROM. Each function of the control device 1 will be described in detail below.

[0023] <Rotation detection unit 31> The rotation detection unit 31 detects the magnetic pole position θ of the rotor in electrical angle (rotation angle θ of the rotor) and the rotation angular velocity ω. In this embodiment, the rotation detection unit 31 detects the magnetic pole position θ (rotation angle θ) and the rotation angular velocity ω of the rotor based on the output signal of the rotation sensor 6. In this embodiment, the magnetic pole position is set to the direction of the N pole of the rotor. Note that the rotation detection unit 31 may be configured to estimate the rotation angle (magnetic pole position) without using a rotation sensor, based on current information or the like obtained by superimposing harmonic components on a current command value (so-called sensorless method).

[0024] <Voltage command calculation unit 32> The voltage command calculation unit 32 calculates and updates three-phase AC voltage command values ​​Vuo, Vvo, and Vwo to be applied to the three-phase windings in an update period Tup. The three-phase AC voltage command values ​​Vuo, Vvo, and Vwo oscillate in an AC period TAC. Each process of the voltage command calculation unit 32 is executed in each update period Tup.

[0025] As will be described in detail later, the update period Tup is set to a value obtained by dividing the carrier period Tca by n (n is a natural number) (Tup=Tca / n), where n is an integer equal to or greater than 1.

[0026] The voltage command calculation unit 32 calculates three-phase AC voltage command values using known vector control. The voltage command calculation unit 32 calculates the current command values Ido and Iqo for the d-axis and q-axis based on the torque command value To, the rotational angular velocity ω, and the DC voltage VDC detected by the voltage sensor 27. The voltage command calculation unit 32 converts the current detection values Iur, Ivr, and Iwr of the three-phase winding detected by the current sensor 28 into the current detection values Idr and Iqr for the d-axis and q-axis based on the magnetic pole position θ. Then, the voltage command calculation unit 32 changes the voltage command values Vdo and Vqo for the d-axis and q-axis by PI control or the like so that the current detection values Idr and Iqr for the d-axis and q-axis approach the current command values Ido and Iqo for the d-axis and q-axis respectively. The voltage command calculation unit 32 converts the voltage command values Vdo and Vqo for the d-axis and q-axis into the three-phase AC voltage command values Vuo, Vvo, and Vwo based on the magnetic pole position θ. Note that known modulation for reducing the amplitude such as two-phase modulation and third harmonic superposition may be applied to the three-phase AC voltage command values Vuo, Vvo, and Vwo. In this embodiment, the case where no modulation is applied will be described.

[0027] <PWM control unit 33> The PWM control unit 33 generates a carrier signal CA that has an amplitude corresponding to the DC voltage VDC supplied to the inverter 20 and oscillates at the carrier period Tca, and on / off controls a plurality of switching elements included in the inverter 20 based on the comparison results between each of the three-phase AC voltage command values Vuo, Vvo, and Vwo and the carrier signal CA.

[0028] As shown in FIG. 5, in this embodiment, the PWM control unit 33 generates a carrier signal CA that has an amplitude of half the DC voltage VDC / 2 and oscillates at the carrier period Tca with the oscillation center value (in this example, 0) of the three-phase AC voltage command value as the center. The carrier signal CA is a triangular wave.

[0029] For each phase, the voltage command calculation unit 32 turns on a switching signal when the AC voltage command value exceeds the carrier signal CA, and turns off the switching signal when the AC voltage command value falls below the carrier signal. The switching signal is transmitted as is to the switching element on the high potential side, and an inverted switching signal is transmitted to the switching element on the low potential side. Each switching signal is input to the gate terminal of each switching element of the inverter 20 via a gate drive circuit, turning each switching element on or off.

[0030] <Periodic change section 34> The period change unit 34 changes one or both of the carrier period Tca and the update period Tup. The changed carrier period Tca is transmitted to the PWM control unit 33 and reflected in the generation of the carrier signal CA. The changed update period Tup is transmitted to the voltage command calculation unit 32 and reflected in the calculation of the AC voltage command value.

[0031] <Increase in low frequency components at a specific number of carrier signals P> The principle of period change is explained below. First, FIG. 4 shows the control behavior of a comparative example in which period change is not performed. The carrier period Tca is set to a constant value, and the update period Tup is set to the carrier period Tca (n=1). The rotational angular velocity ω is swept from low to high. At each rotational angular velocity ω, the oscillation range of the AC voltage command value is overmodulated, exceeding the oscillation range of the carrier signal CA. The graph shows the change in the number of carrier signals P (=TAC / Tca), which is the value obtained by dividing the AC period TAC of the AC voltage command value by the carrier period Tca. The AC period TAC is 2π / ω and is inversely proportional to the rotational angular velocity ω, so the number of carrier signals P decreases as the rotational angular velocity ω increases. The graph also shows the phase currents flowing through the windings of each phase and the DC current IDC flowing between the DC power supply 10 and the inverter 20.

[0032] When the number of carrier signals P becomes 13 and 11, pulsation occurs in the phase current and the DC current IDC.

[0033] Next, Fig. 5 shows an enlarged view of the control behavior when the number of carrier signals P is 11. In Fig. 5, similarly to Fig. 4, the update period Tup is set to the carrier period Tca (n=1).

[0034] FIG. 5 shows the U-phase AC voltage command value Vuo. The U-phase AC voltage command value Vuo is calculated and updated for each carrier cycle Tca. For ease of understanding, the figure shows the U-phase AC voltage command value Vuo as calculated continuously. The oscillation range of the U-phase AC voltage command value Vuo exceeds the oscillation range of the carrier signal CA, resulting in an overmodulation state.

[0035] As described above, the switching signal is generated based on the comparison result between the U-phase AC voltage command value Vuo, which is updated every update period Tup (carrier period Tca), and the carrier signal CA. Because the overmodulation state is in effect, the number of on / off cycles of the switching signal is reduced.

[0036] The phase currents Iu, Iv, and Iw of the respective phases are offset, which causes the DC current IDC to fluctuate greatly.

[0037] Figure 6 shows the control behavior under the same operating conditions as Figure 5. In Figure 6, unlike Figures 4 and 5, the update period Tup is set to Tca / 2 (n=2), which is half the carrier period. Therefore, the update period Tup of the U-phase AC voltage command value Vuo is half that of Figure 5. On the other hand, as in Figure 5, an overmodulation state is occurring, so the number of on / off cycles of the switching signal is reduced.

[0038] However, unlike Fig. 5, no offset occurs in the phase currents Iu, Iv, and Iw of the respective phases, and the fluctuation of the DC current IDC does not become large.

[0039] Therefore, even if the number of carrier signals P is the same, it can be seen that the presence or absence of offset fluctuations in the phase currents changes depending on the set value of the update period Tup.

[0040] The upper part of Figure 7 shows the magnitude of the offset component of the phase current at each carrier signal number P (=TAC / Tca) set by varying the AC period TAC (rotational angular velocity ω) when the carrier period Tca is set to a constant value, the update period Tup is set to the carrier period Tca (n=1), and the system is in an overmodulation state. The lower part of Figure 7 shows the magnitude of the offset component of the phase current at each carrier signal number P (=TAC / Tca) set by varying the AC period TAC (rotational angular velocity ω) when the carrier period Tca is set to the same value as in the upper part of Figure 7, the update period Tup is set to half the carrier period Tca / 2 (n=2), and the system is in the same overmodulation state.

[0041] In the upper part of Fig. 7, the offset component of the phase current increases when the carrier signal number P is 13, 11.5, 11, 9.5, 8.5, 7, 6.5, 5.5, 5, 3.5, etc. Carrier signal numbers P of 11 and 13 match the results when sweeping the rotational angular velocity ω, shown in Fig. 4.

[0042] In the lower part of Figure 7, the offset component of the phase current increases when the carrier signal number P is 11.5, 9.5, 8.5, 6.5, 5.5, 3.5, etc. Compared to the upper part of Figure 7, the offset component does not increase when P = 13, 11, 7, or 5, but the other parts show a similar trend. In addition to the phase current, the voltage and power supplied to the three-phase windings also show an increase in the amplitude of low-frequency components relative to the AC frequency. This is not limited to the offset component; the amplitude of low-frequency components relative to the AC frequency increases for current, voltage, and power.

[0043] Here, assuming that the AC voltage command value of each phase is an ideal sine wave, the AC voltage command value Vo of each phase updated at the update period Tup is expressed by the following equation.

number

[0044] Here, j is the number of the update period Tup and is incremented by one. δ is the phase difference between the phase of the valley of the carrier signal and the phase of the ideal triangular wave, and Δ is the phase of each phase, with Δ=0 for the U phase, Δ=2π / 3 for the V phase, and Δ=4π / 3 for the W phase. A is the amplitude of the AC voltage command value. K is an evaluation coefficient that is set to the smallest natural number such that n×P×K is a natural number.

[0045] From the first equation of Equation (1), we can see that the K-fold value (2π × K) of the AC period TAC, which is a natural number, is divided by the smallest natural number, n × P × K, and the sine value and AC voltage command value Vo are calculated and updated for each divided period. In an overmodulation state, due to voltage saturation, the average applied voltage for each divided period after carrier comparison is at most +VDC / 2 or -VDC / 2. Therefore, when the division number n × P × K is an odd number, the balance between the +VDC / 2 period and the -VDC / 2 period becomes unbalanced by one divided period. Therefore, the total applied voltage for each phase during the TAC × K period shifts from 0 by at most ±VDC / 2 × (TAC × K / (n × P × K)). Therefore, in an overmodulation state, the average applied voltage Vave for each phase shifts by at most ±VDC / 2 / (n × P × K), as shown in the following equation. Therefore, in an overmodulation state, when n×P×K is an odd number, the average value Vave of the applied voltage of each phase shifts from 0, and the amount of shift of the average value Vave of the applied voltage of each phase is inversely proportional to n×P×K.

number

[0046] On the other hand, even if n×P×K is an odd number, if it is a multiple of 3, the shifts in the applied voltages of the U, V, and W phases have a phase difference of 2π / 3 relative to each other. These phases are mutually cancelled out by three-phase balance, and the phase currents of each phase are not offset. Therefore, in an overmodulation state, if n×P×K is an odd number and is not a multiple of 3, offsets in phase currents and the like and an increase in low-frequency components occur. Furthermore, since the shift amount of the average value Vave of the applied voltage of each phase is inversely proportional to n×P×K, as n×P×K increases, the shift amount of the average value Vave of the applied voltage of each phase decreases, and the offset amount of the phase current decreases.

[0047] That is, in an overmodulation state, when the evaluation value N calculated by n×P×K shown in the following formula is an odd number and is not a multiple of 3, the components of frequencies lower than the AC period TAC increase for one or more of the current, voltage, and power supplied to the three-phase windings.

number

[0048] Here, as described above, the evaluation coefficient K is set to the smallest natural number that makes the evaluation value N (= n × P × K) a natural number. As n × P × K increases, the increase in low-frequency components decreases.

[0049] In the upper part of Figure 7, n = 1, so for P = 13, 11.5, 11, 9.5, 8.5, 7, 6.5, 5.5, 5, and 3.5, where the offset component of the phase current increases relatively significantly, K = 1, 2, 1, 1, 2, 2, 1, 2, 2, and 1, respectively, and N = 13, 23, 11, 19, 17, 7, 13, 11, 5, and 7. Therefore, all evaluation values ​​N are odd numbers and are not multiples of 3. Among these, for P = 13, 11, 7, and 5, where K = 1 and N is small, the increase in the offset component is relatively large. On the other hand, for P = 11.5, 9.5, 8.5, 6.5, 5.5, and 3.5, where K = 2 and N is large, the increase in the offset component is small. In addition to the carrier signal number P described here, there are carrier signal numbers P for which the evaluation value N is odd and not a multiple of 3, but we will not explain them here because the evaluation value N becomes larger and the increase in the offset component becomes smaller.

[0050] In the lower row of FIG. 7 , n=2, so P=9.5, 8.5, 6.5, 5.5, and 3.5, where the offset component of the phase current increases relatively significantly, have K=1, 1, 1, 1, and 1, respectively, resulting in N=19, 17, 13, 11, and 7. Therefore, all evaluation values ​​N are odd numbers and are not multiples of 3. Meanwhile, in the upper row where n=1, P=13, 11, 7, and 5, where the increase in the offset component is large, become N=26, 22, 14, and 10, which are even numbers, respectively, in the lower row where n=2, and the offset component does not increase. In addition to the carrier signal numbers P described here, there are carrier signal numbers P where the evaluation value N is odd and is not a multiple of 3. However, these numbers are not described here because the evaluation value N increases and the increase in the offset component becomes small.

[0051] FIG. 8 shows the control behavior when the overmodulation state is close to maximum, the number of carrier signals P is 5, the update period Tup is set to the carrier period Tca (n=1), the evaluation coefficient K is 1, and the evaluation value N (=n×P×K) is 5. The evaluation value N=5 is an odd number and is not a multiple of 3. As explained using Equation (1), the AC period TAC×1 is divided by the evaluation value N=5, and a sine value and an AC voltage command value Vo are calculated for each divided period. However, because the overmodulation state is close to maximum, the average value of the applied voltage for each divided period is +VDC / 2 or −VDC / 2. Because the number of divisions is an odd number (5), there is an imbalance between the +VDC / 2 period and the −VDC / 2 period by one divided period. In FIG. 8, the on-period of the U-phase switching signal is longer than the off-period by one divided period. As a result, the shift amount of the average value Vave of the applied voltage of the U phase becomes VDC / 2 / 5, and the average value of the phase current of the U phase winding shifts to the positive side.

[0052] FIG. 9 shows the control behavior when the overmodulation state is close to maximum, the number of carrier signals P is 5, the update period Tup is set to half the carrier period Tca / 2 (n=2), the evaluation coefficient K is 1, and the evaluation value N (=n×P×K) is 10. The evaluation value N=10 is an even number. As explained using Equation (1), the AC period TAC×1 is divided by the evaluation value N=10, and a sine value and AC voltage command value Vo are calculated for each divided period. However, because the overmodulation state is close to maximum, the average applied voltage for each divided period is +VDC / 2 or −VDC / 2. Because the number of divisions is an even number (10), the periods of +VDC / 2 and −VDC / 2 are equal. In FIG. 9, the on-period and off-period of the U-phase switching signal are equal. As a result, the average value Vave of the U-phase applied voltage does not shift from 0, and the average value of the phase current of the U-phase winding does not shift.

[0053] FIG. 10 shows a graph corresponding to the upper part of FIG. 7. However, the vertical axis has been changed to 1 / N, which correlates with the increase in low-frequency components. Even if the evaluation value N is an odd number and not a multiple of 3, 1 / N decreases as the evaluation value N increases. 1 / N generally correlates with the increase in offset components in the upper part of FIG. 7. In FIG. 10, a threshold line is drawn where 1 / N becomes 1 / B. To effectively suppress the increase in low-frequency components, n and Tca should be set so that 1 / N does not become an evaluation value N that is greater than 1 / B. In the example of FIG. 10, 1 / N is greater than 1 / B when P=13, 11, 7, 6.5, 5.5, 5, 3.5, etc.

[0054] <Periodic change section 34> Therefore, the period changing unit 34 changes one or both of the carrier period Tca and the update period Tup so that the evaluation value N calculated based on the number of carrier signals P, which is the value obtained by dividing the AC period TAC of the AC voltage command value by the carrier period Tca, and the update period Tup does not match a specific value at which the components of frequencies lower than the AC period TAC increase for one or more of the current, voltage, and power supplied to the three-phase windings.

[0055] According to this configuration, when the evaluation value N matches a specific value, the low-frequency components increase. Therefore, by changing one or both of the carrier period Tca and the update period Tup so that the evaluation value N does not match a specific value, the increase in the low-frequency components can be suppressed.

[0056] In this embodiment, the evaluation value N is a value calculated by the above formula (2), and the evaluation coefficient K is set to the smallest natural number that makes the evaluation value N a natural number. The specific value is set to an evaluation value N that is an odd number and is not a multiple of 3. One or more specific values ​​are set.

[0057] According to this configuration, as explained using equations (1) and (2), the K-fold value (2π×K) of the AC period TAC is divided by the evaluation value N (=n×P×K), which is the smallest natural number, and the AC voltage command value Vo for each phase is calculated and updated for each divided period. In an overmodulation state, the average value of the applied voltage for each divided period after carrier comparison becomes at most +VDC / 2 or -VDC / 2 due to voltage saturation. Therefore, when the evaluation value N is an odd number, the balance between the +VDC / 2 period and the -VDC / 2 period becomes unbalanced by one divided period. Therefore, the total value of the applied voltage for each phase during the TAC×K period shifts from 0 by at most ±VDC / 2×(TAC×K / (n×P×K)). Therefore, the average value Vave of the applied voltage for each phase shifts by at most ±VDC / 2 / (n×P×K). On the other hand, even if the evaluation value N is an odd number, if it is a multiple of three, the shift amounts of the U, V, and W phases have a phase difference of 2π / 3 from one another, which cancel each other out due to three-phase balance, and the phase currents of each phase are not offset. Therefore, when the evaluation value N is an odd number and is not a multiple of three, an increase in low-frequency components occurs. Therefore, by setting a specific value to the evaluation value N that is an odd number and is not a multiple of three, and changing one or both of the carrier period Tca and the update period Tup so that the evaluation value N does not match the specific value, it is possible to suppress the increase in low-frequency components.

[0058] In this embodiment, the specific value is set to an evaluation value N that is not an odd number or a multiple of three and is equal to or smaller than the threshold value B.

[0059] 7 and 10, with this configuration, there is a correlation between 1 / N and the increase in low frequency components, and if a specific value is set to evaluation value N when 1 / N is equal to or greater than 1 / B, that is, when N is equal to or less than B, then the specific value is set to evaluation value N where the increase in low frequency components needs to be suppressed, and the increase in low frequency components can be effectively suppressed. For example, B is set to 17.

[0060] For example, in the example of FIG. 10, a specific value may be set to one or more of N=13, 11, 7, 13, 11, 5, 7 corresponding to P=13, 11, 7, 6.5, 5.5, 5, 3.5, respectively, that is, N=13, 11, 7, 5.

[0061] The specific value may be set to an evaluation value N at which the increase in low-frequency components is equal to or greater than a threshold value. Alternatively, the specific value may be set to an evaluation value N at which an increase in low-frequency components becomes a problem.

[0062] In this embodiment, when the oscillation range of the AC voltage command value Vo is in an overmodulation state exceeding the oscillation range of the carrier signal CA, the period changing unit 34 changes one or both of the carrier period Tca and the update period Tup so that the evaluation value N does not match a specific value.

[0063] Figure 11 shows the control behavior in the case of overmodulation when n=1, P=7, and N=7. In the overmodulation state, the number of on / off cycles of the switching signal becomes less than the number of carrier signals due to voltage saturation, and the continuous on and off periods become longer, making it more likely that an imbalance will occur between the on and off periods of the switching signal. As a result, a shift in the phase current of each phase will easily occur.

[0064] On the other hand, Figure 12 shows the control behavior when n = 1, P = 7, and N = 7 and there is no overmodulation state. When there is no overmodulation state, the number of on / off cycles of the switching signal does not decrease relative to the number of carrier signals, and the continuous on period and continuous off period do not become long, making it difficult for imbalances to occur between the on and off periods of the switching signals. As a result, shifts in the phase currents of each phase are unlikely to occur. Therefore, by changing the period when there is an overmodulation state, it is possible to effectively suppress an increase in low-frequency components. Note that even when there is no overmodulation state, the period change unit 34 may change one or both of the carrier period Tca and the update period Tup so that the evaluation value N does not match the specific value.

[0065] In this embodiment, the period changing unit 34 determines whether or not an overmodulation state is occurring based on a modulation factor M, which is the ratio of the line voltages of the three-phase AC voltage command values ​​to the DC voltage VDC. The period changing unit 34 calculates the modulation factor M based on the d-axis and q-axis voltage command values ​​Vdo, Vqo and the DC voltage VDC using the following equation.

number

[0066] In this embodiment, the period varying unit 34 determines that the signal is in an overmodulation state when the modulation factor M is 1 or greater, and determines that the signal is not in an overmodulation state (normal modulation) when the modulation factor M is less than 1. Note that the threshold value may be increased or decreased from 1, taking into account factors such as the amount of increase in low-frequency components.

[0067] When known modulation for reducing amplitude, such as two-phase modulation or third-order harmonic superposition, is applied to the three-phase AC voltage command values ​​Vuo, Vvo, and Vwo, the period changing unit 34 determines that an overmodulation state exists when the modulation factor M is 1.15 or more, and determines that an overmodulation state does not exist when the modulation factor M is less than 1.15. In this case as well, the threshold value may be increased or decreased from 1.15.

[0068] For example, the overmodulation state region and the normal modulation state region are as shown in Fig. 13. The overmodulation state exists in the region of high rotational angular velocity and high torque.

[0069] <Periodic change based on AC cycle TAC> The period changing unit 34 changes one or both of the carrier period Tca and the update period Tup based on the AC period TAC so that the evaluation value N does not match a specific value. Instead of the AC period TAC, the AC frequency 1 / TAC or the rotational angular velocity ω may be used.

[0070] As shown in equation (3), the number P of carrier signals correlated with the evaluation value N changes depending on the AC cycle TAC. Therefore, based on the AC cycle TAC, it is possible to determine whether the evaluation value N matches a specific value when one or both of the carrier cycle Tca and the update cycle Tup are not changed. Then, based on the AC cycle TAC, it is possible to accurately change one or both of the carrier cycle Tca and the update cycle Tup so that the evaluation value N does not match the specific value.

[0071] For example, the period changing unit 34 refers to map data in which the relationship between the AC period TAC and one or both of the set values ​​of the carrier period Tca and the update period Tup at which the evaluation value N does not match a specific value is preset, and calculates and sets one or both of the set values ​​of the carrier period Tca and the update period Tup that correspond to the current AC period TAC. Instead of the carrier period Tca, the carrier frequency 1 / Tca may be set.

[0072] <When changing the carrier period Tca> For example, as explained using Fig. 10, when the update period Tup is set to the carrier period Tca (n=1), evaluation values ​​N=13, 11, 7 corresponding to the carrier signal numbers P=13, 11, 7 may be set as specific values. Fig. 14 shows the AC frequency 1 / TAC on the horizontal axis and the carrier frequency 1 / Tca on the vertical axis, and illustrates lines corresponding to the carrier signal numbers P of 13, 11, 7, and examples of setting values ​​for the carrier frequency 1 / Tca.

[0073] As shown in FIG. 14, the carrier frequency 1 / Tca is changed based on the AC frequency 1 / TAC so as to avoid the number of carrier signals P=13, 11, and 7 corresponding to the specific values ​​13, 11, and 7. Map data is set in advance, in which the relationship between the AC frequency 1 / TAC and the set value of the carrier frequency 1 / Tca is set as shown in FIG. 14. In the example of FIG. 14, the number of carrier signals P to be avoided is set to 13, 11, and 7, but the value of the number of carrier signals P to be avoided may be changed depending on the operating range of the AC frequency 1 / TAC, the set range of the carrier frequency 1 / Tca, and the set value of the update period Tup. The map data may be set to any value different from that shown in FIG. 14, as long as the carrier frequency 1 / Tca is set so as to avoid one or more number of carrier signals P corresponding to one or more specific values.

[0074] 15, under specific conditions where the evaluation value N approaches a specific value when the carrier period Tca is set to a predetermined first carrier period Tca1, the period changing unit 34 may set the carrier period Tca to a predetermined second carrier period Tca2 so that the evaluation value N does not match the specific value, and may set the carrier period Tca to the first carrier period Tca1 under conditions other than the specific conditions. In the case of FIG. 15, the update period Tup is set to the carrier period Tca (n=1), and evaluation values ​​N=13, 11, 7 corresponding to the carrier signal numbers P=13, 11, 7 are set as specific values. In the example of FIG. 15, when the first carrier frequency 1 / Tca1 is set, the carrier frequency 1 / Tca is set to the second carrier frequency 1 / Tca2 in a specific region of the AC frequency 1 / TAC where the evaluation value N approaches the specific values ​​13 and 11. In the example of FIG. 15, the second carrier frequency 1 / Tca2 is set to a frequency lower than the first carrier frequency 1 / Tca1, but may be set to a higher frequency.

[0075] Alternatively, as shown in FIG. 16 , the period varying unit 34 may randomly vary the carrier period Tca under specific conditions where the evaluation value N approaches a specific value when the carrier period Tca is set to a predetermined first carrier period Tca1, and may set the carrier period Tca to the first carrier period Tca1 under conditions other than the specific conditions. In the example of FIG. 16 , when the first carrier frequency 1 / Tca1 is set, the carrier frequency 1 / Tca is randomly varied in a specific range of the AC frequency 1 / TAC where the evaluation value N approaches specific values ​​13 and 11. In the example of FIG. 16 , the carrier frequency 1 / Tca is randomly varied within a predetermined range centered on the first carrier frequency 1 / Tca1. By varying the carrier period 1 / Tca randomly, the period during which the evaluation value N matches the specific value can be significantly shortened.

[0076] In the example of Figure 16, the specific values ​​13 and 11 are combined to set one specific region of AC frequency 1 / TAC and are changed randomly, but it is also possible to set a specific region for the specific value 13 and a specific region for the specific value 11 separately and change each specific region randomly.

[0077] <When changing the update cycle Tup> For example, when the update period Tup is set to the carrier period Tca (n=1), evaluation values ​​N=13, 11, 7 corresponding to the carrier signal numbers P=13, 11, 7 are set as specific values, but when the update period Tup is set to half the carrier period Tca / 2 (n=2), no specific value is set. In other words, the specific value changes depending on the update period Tup. Figure 17 shows the AC frequency 1 / TAC on the horizontal axis and the carrier frequency 1 / Tca on the vertical axis, with lines corresponding to the carrier signal numbers P of 13, 11, 7 and example setting values ​​for the carrier frequency 1 / Tca.

[0078] As shown in Fig. 17, the carrier frequency 1 / Tca is set to a constant value. On the other hand, the update period Tup is changed based on the carrier period Tca so as to avoid the specific values ​​13, 11, and 7 when n = 1. Map data is set in advance, in which the relationship between the AC frequency 1 / TAC and the set value of the update period Tup(n) is set, as shown in Fig. 17. Note that in the example of Fig. 17, the number P of carrier signals to be avoided when n = 1 is set to 13, 11, and 7, but the value of the number P of carrier signals to be avoided may be changed depending on the operating range of the AC frequency 1 / TAC, the set range of the carrier frequency 1 / Tca, and the set value of the update period Tup.

[0079] 18, under certain conditions in which the evaluation value N approaches a specific value when the update period Tup is set to a predetermined first update period Tup1, the period changing unit 34 sets the update period Tup to a predetermined second update period Tup2 so that the evaluation value N does not match the specific value, and sets the update period Tup to the first update period Tup1 under conditions other than the specific condition. In the case of FIG. 18, the first update period Tup1 is set to the carrier period Tca (n=1), and the second update period Tup2 is set to a half period Tca / 2 (n=2) of the carrier period. The specific values ​​of the first update period Tup1 are 13, 11, and 7, and there is no specific value for the second update period Tup2. When the first update period Tup1 matches the specific value, the specific value can be avoided by changing to the second update period Tup2. In the example of FIG. 18, when the first update period Tup1 is set, the update period Tup is set to the second update period Tup2 in a specific region of the AC frequency 1 / TAC where the evaluation value N approaches the specific values ​​13 and 11.

[0080] The period changing unit 34 may simultaneously change the carrier period Tca and the update period Tup based on the AC period TAC so that the evaluation value N does not match a specific value.

[0081] 2. Second Embodiment Next, an AC rotating electric machine 5 and a control device 1 according to a second embodiment will be described. Description of components similar to those of the first embodiment will be omitted. The basic configuration of the AC rotating electric machine 5 and the control device 1 according to this embodiment is similar to that of the first embodiment, but the PWM control unit 33 is configured to execute the synchronous PWM mode, and accordingly, the processing of the period changing unit 34 is different.

[0082] In this embodiment, the PWM control unit 33 executes a synchronous PWM mode in which the carrier period Tca is changed in proportion to the AC period TAC. In the synchronous PWM mode, the carrier frequency 1 / Tca is set to a value obtained by multiplying the AC frequency 1 / TAC by a proportionality coefficient Kp, which is a natural number. The PWM control unit 33 can also execute an asynchronous PWM mode in which the carrier period Tca is changed not in proportion to the AC period TAC. For example, the PWM control unit 33 executes the asynchronous PWM mode when the rotational angular velocity ω is less than a switching value, and executes the synchronous PWM mode when the rotational angular velocity ω is equal to or greater than the switching value.

[0083] When the synchronous PWM mode is executed, the period changing unit 34 sets a proportional coefficient Kp so that the evaluation value N does not match a specific value, and uses the set proportional coefficient Kp to change the carrier period Tca in proportion to the AC period TAC.

[0084] 19, when the update period Tup is set to the carrier period Tca (n=1), evaluation values ​​N=13, 11, 7 corresponding to the number of carrier signals P=13, 11, 7 are set as specific values. In the example of FIG. 19, in the region of the AC frequency 1 / TAC (rotational angular velocity ω) where the synchronous PWM mode is executed, the evaluation value N does not approach the specific values ​​13, 11, 7, but in the region of the AC frequency 1 / TAC where the asynchronous PWM mode is executed, the evaluation value N approaches the specific values ​​13, 11, 7.

[0085] The proportionality coefficient Kp is changed based on the AC frequency 1 / TAC so as to avoid the carrier signal numbers P=13, 11, and 7 corresponding to the specific values ​​13, 11, and 7. That is, the proportionality coefficient Kp is set to a natural number other than the specific values ​​13, 11, and 7. In the example of FIG. 19, the proportionality coefficient Kp is set to 12 and 9. Map data as shown in FIG. 19 is set in advance, in which the relationship between the AC frequency 1 / TAC and the set value of the proportionality coefficient Kp is set. In this way, by setting the proportionality coefficient Kp so that the evaluation value N does not match the specific value, an increase in low-frequency components can be suppressed.

[0086] In the execution region of the synchronous PWM mode, if the evaluation value N matches a specific value, the processing of the first embodiment may be executed.

[0087] <Other embodiments> (1) In the above embodiments, an example has been described in which a three-phase winding is provided. However, the number of winding phases Q may be set to any number, such as 2 or 4, as long as it is plural. In this case, the specific value may be set to an evaluation value N that is an odd number and is not a multiple of the number of phases Q.

[0088] (2) In the above embodiments, the case where one set of three-phase windings is provided has been described as an example. However, multiple sets of multiple-phase windings may be provided. In this case, the processing of each of the above embodiments may be performed for the multiple windings of each set.

[0089] <Summary of various aspects of the present application> Various aspects of the present application will be summarized below as appendices.

[0090] (Appendix 1) A control device for an AC rotating electric machine that controls an AC rotating electric machine having a plurality of phase windings via an inverter, a voltage command calculation unit that calculates and updates AC voltage command values ​​for multiple phases to be applied to the windings of the multiple phases in an update period; a PWM control unit that generates a carrier signal that has an amplitude according to the DC voltage supplied to the inverter and oscillates with a carrier period, and controls on / off of a plurality of switching elements included in the inverter based on a comparison result between each of the AC voltage command values ​​of the plurality of phases and the carrier signal; a period changing unit that changes one or both of the carrier period and the update period; Equipped with the period changing unit changes one or both of the carrier period and the update period so that an evaluation value calculated based on the update period and the number of carrier signals, which is a value obtained by dividing the AC period of the AC voltage command value by the carrier period, does not match a specific value in which a frequency component lower than the AC period increases for one or more of the current, voltage, and power supplied to the plurality of windings.

[0091] (Appendix 2) 2. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit changes one or both of the carrier period and the update period so that the evaluation value does not match the specific value when an oscillation range of the AC voltage command value is in an overmodulation state exceeding an oscillation range of the carrier signal.

[0092] (Appendix 3) 3. The control device for an AC rotating electric machine according to claim 1, wherein the update period is set to a value obtained by dividing the carrier period by n (n is a natural number).

[0093] (Appendix 4) the number of phases of the multiple phase windings is Q; When the evaluation value is N, the number of carrier signals is P, and an evaluation coefficient set to a natural number is K, the evaluation value is expressed as follows: N=n×P×K The evaluation coefficient is set to the smallest natural number that makes the evaluation value a natural number. 4. The control device for an AC rotating electric machine according to claim 3, wherein the specific value is set to the evaluation value that is an odd number and a value other than a multiple of Q.

[0094] (Appendix 5) 5. The control device for an AC rotating electric machine according to claim 4, wherein the specific value is set to a value other than an odd number and a multiple of Q, and to the evaluation value that is equal to or smaller than a threshold value.

[0095] (Appendix 6) 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit changes one or both of the carrier period and the update period based on the AC period so that the evaluation value does not match the specific value.

[0096] (Appendix 7) The control device for an AC rotating electric machine according to Appendix 6, wherein the period changing unit refers to map data in which a relationship between the AC period and one or both of a set value of the carrier period and a set value of the update period for which the evaluation value does not match the specific value is preset, and calculates and sets one or both of a set value of the carrier period and a set value of the update period that correspond to the current AC period.

[0097] (Appendix 8) 6. The control device for an AC rotating electric machine according to claim 1, wherein, under specific conditions in which the evaluation value approaches the specific value when the carrier period is set to a predetermined first carrier period, the period changing unit sets the carrier period to a predetermined second carrier period so that the evaluation value does not match the specific value, and sets the carrier period to the first carrier period under conditions other than the specific condition.

[0098] (Appendix 9) 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit randomly changes the carrier period under a specific condition in which the evaluation value approaches the specific value when the carrier period is set to a predetermined first carrier period, and sets the carrier period to the first carrier period under conditions other than the specific condition.

[0099] (Appendix 10) the PWM control unit executes a synchronous PWM mode in which the carrier period is changed in proportion to the AC period; 8. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit sets a proportionality coefficient so that the evaluation value does not match the specific value when the synchronous PWM mode is executed, and changes the carrier period in proportion to the AC period using the set proportionality coefficient.

[0100] (Appendix 11) 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit sets the update period to a second update period that is set in advance so that the evaluation value does not match the specific value under a specific condition in which the evaluation value approaches the specific value when the update period is set to a first update period that is set in advance, and sets the update period to the first update period under conditions other than the specific condition.

[0101] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0102] 1 AC rotating electric machine control device, 5 AC rotating electric machine, 20 inverter, 32 voltage command calculation unit, 33 PWM control unit, 34 period change unit, B threshold value, CA carrier signal, K evaluation coefficient, N evaluation value, P number of carrier signals, Q number of phases, TAC AC period, Tca carrier period, Tca1 first carrier period, Tca2 second carrier period, Tup update period, Tup1 first update period, Tup2 second update period

Claims

1. A control device for an AC rotating electric machine that controls an AC rotating electric machine having a plurality of phase windings via an inverter, a voltage command calculation unit that calculates and updates AC voltage command values ​​for multiple phases to be applied to the windings of the multiple phases in an update period; a PWM control unit that generates a carrier signal having an amplitude corresponding to the DC voltage supplied to the inverter and oscillating with a carrier period, and controls on / off of a plurality of switching elements included in the inverter based on a comparison result between each of the AC voltage command values ​​of the plurality of phases and the carrier signal; a period changing unit that changes one or both of the carrier period and the update period; Equipped with the period changing unit changes one or both of the carrier period and the update period so that an evaluation value calculated based on the update period and a number of carrier signals, which is a value obtained by dividing the AC period of the AC voltage command value by the carrier period, does not match a specific value in which a frequency component lower than the AC period increases for one or more of the current, voltage, and power supplied to the plurality of windings.

2. 2. The control device for an AC rotating electric machine according to claim 1, wherein, when an oscillation range of the AC voltage command value is in an overmodulation state exceeding an oscillation range of the carrier signal, the period changing unit changes one or both of the carrier period and the update period so that the evaluation value does not match the specific value.

3. 2. The control device for an AC rotating electric machine according to claim 1, wherein the update period is set to a value obtained by dividing the carrier period by n (n is a natural number).

4. the number of phases of the multiple-phase windings is Q; When the evaluation value is N, the number of carrier signals is P, and an evaluation coefficient set to a natural number is K, the evaluation value is expressed as follows: N = n x P x K The evaluation coefficient is set to the smallest natural number that makes the evaluation value a natural number.

4. The control device for an AC rotating electric machine according to claim 3, wherein the specific value is set to an odd number other than a multiple of Q.

5. 5. The control device for an AC rotating electric machine according to claim 4, wherein the specific value is set to a value other than an odd number and a multiple of Q, and the evaluation value is set to a value equal to or smaller than a threshold value.

6. 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit changes one or both of the carrier period and the update period based on the AC period so that the evaluation value does not match the specific value.

7. 7. The control device for an AC rotating electric machine according to claim 6, wherein the period changing unit refers to map data in which a relationship between the AC period and one or both of a set value of the carrier period and a set value of the update period for which the evaluation value does not match the specific value is preset, and calculates and sets one or both of the set value of the carrier period and the set value of the update period that correspond to the current AC period.

8. 6. The control device for an AC rotating electric machine according to claim 1, wherein, under specific conditions in which the evaluation value approaches the specific value when the carrier period is set to a predetermined first carrier period, the period changing unit sets the carrier period to a predetermined second carrier period so that the evaluation value does not match the specific value, and sets the carrier period to the first carrier period under conditions other than the specific condition.

9. 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit randomly changes the carrier period under specific conditions in which the evaluation value approaches the specific value when the carrier period is set to a predetermined first carrier period, and sets the carrier period to the first carrier period under conditions other than the specific conditions.

10. the PWM control unit executes a synchronous PWM mode in which the carrier period is changed in proportion to the AC period; 6. The control device for an AC rotating electric machine according to claim 1, wherein the period changing unit sets a proportionality coefficient so that the evaluation value does not match the specific value when the synchronous PWM mode is executed, and changes the carrier period in proportion to the AC period using the set proportionality coefficient.

11. 6. The control device for an AC rotating electric machine according to claim 1, wherein, under a specific condition in which the evaluation value approaches the specific value when the update period is set to a predetermined first update period, the period changing unit sets the update period to a predetermined second update period in which the evaluation value does not match the specific value, and sets the update period to the first update period under conditions other than the specific condition.

Images