Rotary electric machine driving device and rotary electric machine driving method

Abstract

A rotary electric machine driving device (1) comprises: power converters (3) and (4) of a plurality of groups, said power converters (3) and (4) being provided corresponding to respective groups, converting DC power inputted from a DC power source (7) into phase currents, and outputting the result to respective stator windings of the groups; and a control unit (5) that outputs a control signal generated on the basis of a carrier wave, controls the power converters (3) and (4) of each group, and switches the phase of the carrier wave in each group when the temperature of a section of a rotary electric machine (2) is higher than a threshold temperature.

Description

Rotating electric machine drive device and rotating electric machine drive method

[0001] The present disclosure relates to a rotating electric machine drive device and a rotating electric machine drive method.

[0002] A commonly known rotating electric machine drive technology is a multiple drive technology in which a single rotating electric machine is driven by multiple groups of power conversion devices. When a rotating electric machine is driven by PWM (Pulse Width Modulation) control, harmonic currents flow through the rotating electric machine, and these harmonic currents cause increased loss and vibration in the rotating electric machine.

[0003] Furthermore, there is a control technique for shifting the phase of harmonic current components generated in each group when multiple groups of power conversion devices are used. For example, Patent Document 1 describes a drive system that applies AC voltages of equal magnitude but opposite phase to a rotating electric machine having two sets of three-phase windings that are out of phase with each other by an electrical angle of 180 degrees.

[0004] International Publication No. 2014 / 132385

[0005] The conventional technology described in Patent Document 1 applies AC voltages of opposite phases to two sets of three-phase windings of a rotating electric machine, thereby increasing inductance and reducing current ripple. However, Patent Document 1 does not describe control for reducing loss in the rotating electric machine, which leads to an increase in loss in each part of the rotating electric machine, resulting in a problem of temperature rise.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a rotating electric machine drive device that can reduce losses occurring in each part of the rotating electric machine and suppress temperature increases in parts that exceed a threshold temperature.

[0007] The rotating electric machine drive device according to the present disclosure is a rotating electric machine drive device that drives a rotating electric machine having a stator with multiple groups of stator windings of three or more phases and a rotor that is a rotating body, and is equipped with multiple groups of power converters that are provided corresponding to each group and convert DC power input from a power source into phase current and output it to the stator windings of each group, and a control unit that outputs a control signal generated based on a carrier wave to control the power converters of each group, and switches the phase of the carrier wave in each group when the temperature of a part of the rotating electric machine is higher than a threshold temperature.

[0008] According to the present disclosure, when the temperature of a part of a rotating electric machine is higher than a threshold temperature, the phase of the carrier wave in each group can be switched to reduce losses occurring in each part of the rotating electric machine and suppress temperature rise in parts that exceed the threshold temperature.

[0009] 1 is a circuit diagram showing an example of the configuration of a rotary electric machine drive device according to a first embodiment. FIG. 2 is a block diagram showing an example of the configuration of a control unit according to the first embodiment. FIG. 3 is a cross-sectional view showing a cross-section of a permanent magnet synchronous rotary electric machine. FIG. 4 is a cross-sectional view showing a cross-section of an induction rotary electric machine. FIG. 5 is a cross-sectional view showing a first and second group winding configuration in a rotary electric machine having two slots per pole per phase (hereinafter referred to as per pole per phase (2)). FIG. 6 is a cross-sectional view showing a first and second group winding configuration in a rotary electric machine having four slots per pole per phase (hereinafter referred to as per pole per phase (4)). FIG. 7 is a graph showing amplitude versus phase of phase currents in the first and second groups. FIG. 8 is a waveform diagram showing carrier waves of the first group and carrier waves of the second group. FIG. 9 is a waveform diagram showing the phase difference between the carrier waves of the first group and carrier waves of the second group emphasized by expanding the phase range. FIG. 10 is a graph showing rotor loss versus carrier wave phase difference between the first and second groups. FIG. 11 is a flowchart showing a rotary electric machine drive method according to the first embodiment. 17A and 17B are block diagrams showing a hardware configuration that realizes the functions of a control unit included in the rotary electric machine drive device according to the first embodiment. 17B is a waveform diagram showing a triangular carrier wave and a phase voltage signal wave. 17C is a graph showing a harmonic voltage amplitude with respect to a DC voltage in a carrier primary component versus a modulation factor. 17D is a graph showing a harmonic voltage amplitude with respect to a DC voltage in a carrier secondary component versus a modulation factor. 17E is a graph showing a carrier harmonic component that appears in the first and second groups with respect to a frequency and a rotation speed. 17F is a block diagram showing a hardware configuration that realizes the functions of a control unit included in the rotary electric machine drive device according to the first embodiment.

[0010] First Embodiment. Fig. 1 is a circuit diagram showing an example of the configuration of a rotary electric machine drive device 1 according to a first embodiment. In Fig. 1, the rotary electric machine drive device 1 is a device that drives a rotary electric machine 2 and is configured to include a first group power converter 3, a second group power converter 4, and a control unit 5. A DC bus 3a is switched by a power switch 6a, and a DC bus 3b is switched by a power switch 6b. The first group power converter 3 and the second group power converter 4 are connected to a DC power source 7 via the DC bus 3a and the DC bus 3b, and receive drive power from the DC power source 7 and output regenerative power to the DC power source 7. The first group power converter 3 and the second group power converter 4 are also connected to the rotary electric machine 2 via an AC bus 2a, and output drive power to the rotary electric machine 2 and receive regenerative power from the rotary electric machine 2.

[0011] The rotating electric machine 2 is a rotating electric machine including a stator having multiple groups of stator windings of three or more phases, and a rotor which is a rotating body. The rotating electric machine 2 is equipped with a rotation angle sensor 21 which detects the rotation angle of the rotor, and a temperature detection unit 22 which detects the temperatures of the stator and the rotor. For example, the rotating electric machine 2 is a multiple rotating electric machine including three-phase stator windings driven by two systems, group 1 and group 2.

[0012] The first group power converter 3 is a first group power converter including a first group capacitor 31, a first group power conversion circuit 32, and a rotating electric machine current detection unit 33. "First group" refers to the first group. The first group capacitor 31 is a smoothing capacitor connected between the DC bus 3a and the DC bus 3b on the power input side of the first group power conversion circuit 32. The first group power conversion circuit 32 is a circuit including switching elements 321 to 326, and performs DC-AC power conversion by the switching operation of the switching elements 321 to 326. The rotating electric machine current detection unit 33 detects the current of the rotating electric machine 2 flowing through the AC bus 2a.

[0013] The first group power conversion circuit 32 is an inverter circuit in which switching elements 321, 322, 323, 324, 325, and 326 are full-bridge connected. In the first group power conversion circuit 32, the switching elements 321 and 322 are connected in series, the switching elements 323 and 324 are connected in series, and the switching elements 325 and 326 are connected in series. The series-connected switching elements 321 and 322, the series-connected switching elements 323 and 324, and the series-connected switching elements 325 and 326 are connected in parallel to the DC power supply 7.

[0014] A group of U-phase input terminals of the rotary electric machine 2 is connected to a connection point between the series-connected switching elements 321 and 322. A group of V-phase input terminals of the rotary electric machine 2 is connected to a connection point between the series-connected switching elements 323 and 324. A group of W-phase input terminals of the rotary electric machine 2 is connected to a connection point between the series-connected switching elements 325 and 326. Here, the switching elements 321, 323, and 325 connected to the DC bus 3a are called upper-stage switching elements, and the switching elements 322, 324, and 326 connected to the DC bus 3b are called lower-stage switching elements.

[0015] The switching elements 321 to 326 are, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) as shown in Fig. 1. In addition to MOSFETs, IGBTs (Insulated Gate Bipolar Transistors) or the like may also be used. A freewheel diode (FWD) is provided in parallel with each of the MOSFETs that are the switching elements 321 to 326, with the forward direction being the direction from the negative side to the positive side of the DC power supply 7, that is, the direction from the lower side to the upper side.

[0016] The two-group power converter 4 is a two-group power converter including a two-group capacitor 41, a two-group power conversion circuit 42, and a rotating electric machine current detection unit 43. The two-group refers to the second group. The two-group capacitor 41 is a smoothing capacitor connected between the DC bus 3a and the DC bus 3b on the power input side of the two-group power conversion circuit 42. The two-group power conversion circuit 42 is a circuit including switching elements 421 to 426, and performs DC-AC power conversion by the switching operation of the switching elements 421 to 426. The rotating electric machine current detection unit 43 detects the current of the rotating electric machine 2 flowing through the AC bus 2a.

[0017] The two-group power conversion circuit 42 is an inverter circuit in which switching elements 421, 422, 423, 424, 425, and 426 are full-bridge connected. In the two-group power conversion circuit 42, the switching elements 421 and 422 are connected in series, the switching elements 423 and 424 are connected in series, and the switching elements 425 and 426 are connected in series. The series-connected switching elements 421 and 422, the series-connected switching elements 423 and 424, and the series-connected switching elements 425 and 426 are connected in parallel to the DC power supply 7.

[0018] Two groups of U-phase input terminals of the rotary electric machine 2 are connected to a connection point between the series-connected switching elements 421 and 422. Two groups of V-phase input terminals of the rotary electric machine 2 are connected to a connection point between the series-connected switching elements 423 and 424. Two groups of W-phase input terminals of the rotary electric machine 2 are connected to a connection point between the series-connected switching elements 425 and 426. Here, the switching elements 421, 423, and 425 connected to the DC bus 3a are called upper-stage switching elements, and the switching elements 422, 424, and 426 connected to the DC bus 3b are called lower-stage switching elements.

[0019] 1 is used for the switching elements 421 to 426. In addition to MOSFETs, IGBTs or the like may also be used. A freewheel diode (FWD) is provided in parallel with each MOSFET that is the switching elements 421 to 426, with the forward direction being the direction from the negative side to the positive side of the DC power supply 7, that is, the direction from the lower side to the upper side.

[0020] The first group power converter 3 and the second group power converter 4 may use the same type of semiconductor switching elements, or different elements may be used. For example, when the same type of semiconductor switching elements are used, the first group power converter 3 and the second group power converter 4 may use MOSFETs or IGBTs as the switching elements. When different types of semiconductor switching elements are used, the first group power converter 3 may use MOSFETs and the second group power converter 4 may use IGBTs as the switching elements. The switching operations of the first group power converter 3 and the second group power converter 4 are controlled by the control unit 5.

[0021] The rotating electric machine current detection unit 33 detects the current flowing through the AC bus 2a and outputs rotating electric machine current information obtained by converting the current into a voltage to the control unit 5. In the example of FIG. 1 , the current is detected by a shunt resistor that is the rotating electric machine current detection unit 33. Note that the rotating electric machine current detection unit 33 may also be realized by a current sensor that uses a magnetic sensor such as a Hall element.

[0022] The power switch 6a controls the exchange of power between the DC power source 7 and the first group power converter 3, and the power switch 6b controls the exchange of power between the DC power source 7 and the second group power converter 4. The power switches 6a and 6b are held open by a higher-level system when, for example, the voltage of the DC power source 7 exceeds a set value during regenerative operation of the rotating electric machine 2, when the voltage of the DC power source 7 falls below a set value due to consumption of the DC power source 7 or the like, or when the current flowing through the DC power source 7 exceeds a set value. The power switches 6a and 6b may be configured to be controlled by the control unit 5.

[0023] The rotation angle sensor 21 detects the rotation angle of the rotor included in the rotating electric machine 2 using a resolver, an encoder, a magnetic sensor, or the like. Information indicating the rotation angle of the rotor detected by the rotation angle sensor 21 is output to the control unit 5. The temperature detection unit 22 detects the temperature of the stator and the rotor included in the rotating electric machine 2. Information indicating the temperature of each part of the rotating electric machine 2 detected by the temperature detection unit 22 is output to the control unit 5. Furthermore, the temperature detection unit 22 may detect the temperature in a different way depending on the part of the rotating electric machine 2. For example, the temperature detection unit 22 may be a thermistor or a thermocouple.

[0024] 1 illustrates a case in which the rotating electric machine drive device 1 includes the first group power converter 3 and the second group power converter 4, but is not limited to this. That is, the rotating electric machine drive device 1 may include not only two systems (first group and second group) but also multiple systems (three or more groups). For example, the rotating electric machine drive device 1 includes multiple systems (three or more groups) including smoothing capacitors, power conversion circuits, rotating electric machine current detection units, and switching elements of the power conversion circuits.

[0025] The control unit 5 controls the first group power converters 3 and the second group power converters 4 by outputting control signals generated based on the carrier waves, and switches the phase of the carrier waves in each group when the temperature of a part of the rotating electric machine 2 is higher than a threshold temperature. Fig. 2 is a block diagram showing an example configuration of the control unit 5. In Fig. 2, the control unit 5 includes a current command generation unit 51, a three-phase to two-phase conversion unit 52, a current control unit 53, a two-phase to three-phase conversion unit 54, a carrier wave generation unit 55, and a PWM signal generation unit 56.

[0026] The current command generator 51 generates a torque command Trq ＊ Based on this, the first group d-axis current command value Id1 ＊ and the first group q-axis current command value Iq1 ＊ and the second group d-axis current command value Id2 ＊ and the second group q-axis current command value Iq2 ＊ Here, the d-axis indicates the direction in which the magnetic flux of the permanent magnet, which is the rotor of the rotary electric machine 2, is generated, and the q-axis is an axis electrically perpendicular to the d-axis. ＊is control information that specifies the torque of the rotor included in the rotating electric machine 2, and is generated, for example, in a host system that controls the rotating electric machine drive device 1, and is acquired by the current command generation unit 51 from the host system. ＊ is the d-axis current command value of the first group, and the q-axis current command value of the first group Iq1 ＊ is the current command value in the q-axis direction of the first group. ＊ is the d-axis current command value of the second group, and the q-axis current command value of the second group Iq2 ＊ is the current command value in the q-axis direction of the second group.

[0027] The current command generating unit 51 may have a plurality of current command maps for torque commands created using the results of actual measurements or simulations performed in advance. In this case, the current command generating unit 51 may generate a torque command Trq ＊ As a result of searching the map based on ＊ and the first group q-axis current command value Iq1 ＊ and the second group d-axis current command value Id2 ＊ and the second group q-axis current command value Iq2 ＊ and may be generated.

[0028] Three-phase to two-phase conversion unit 52 receives as input first group U-phase current Iu1, first group V-phase current Iv1, and first group W-phase current Iw1 from rotating electric machine current detection unit 33, receives as input second group U-phase current Iu2, second group V-phase current Iv2, and second group W-phase current Iw2 from rotating electric machine current detection unit 43, and receives as input electrical angle θe from rotation angle sensor 21. First group U-phase current Iu1 is a current value flowing through the first group U-phase stator winding, first group V-phase current Iv1 is a current value flowing through the first group V-phase stator winding, and first group W-phase current Iw1 is a current value flowing through the first group W-phase stator winding. The second group U-phase current Iu2 is a current value flowing through the second group U-phase stator winding, the second group V-phase current Iv2 is a current value flowing through the second group V-phase stator winding, and the second group W-phase current Iw2 is a current value flowing through the second group W-phase stator winding. The electrical angle θe is the rotation angle of the rotor provided in the rotating electric machine 2.

[0029] The three-to-two-phase converter 52 performs three-to-two-phase coordinate transformation based on the first group U-phase current Iu1, the first group V-phase current Iv1, the first group W-phase current Iw1, the second group U-phase current Iu2, the second group V-phase current Iv2, and the second group W-phase current Iw2, and the electrical angle θe to convert the first group U-phase current Iu1, the first group V-phase current Iv1, and the first group W-phase current Iw1 into a first group d-axis current detection value Id1 and a first group q-axis current detection value Iq1, and convert the second group U-phase current Iu2, the second group V-phase current Iv2, and the second group W-phase current Iw2 into a second group d-axis current detection value Id2 and a second group q-axis current detection value Iq2. The first group d-axis current detection value Id1 is the detected value of the first group current in the d-axis direction, and the first group q-axis current detection value Iq1 is the detected value of the first group current in the q-axis direction. The second group d-axis current detection value Id2 is the second group current detection value in the d-axis direction, and the second group q-axis current detection value Iq2 is the second group current detection value in the q-axis direction.

[0030] The current control unit 53 receives the first group d-axis current command value Id1 from the current command generation unit 51. ＊ and the first group q-axis current command value Iq1 ＊ and the second group d-axis current command value Id2 ＊ and the second group q-axis current command value Iq2 ＊ Furthermore, the current control unit 53 receives the first group d-axis current detection value Id1, the first group q-axis current detection value Iq1, the second group d-axis current detection value Id2, and the second group q-axis current detection value Iq2 from the three-phase to two-phase conversion unit 52.

[0031] The current control unit 53 calculates the first group d-axis current command value Id1 ＊ and the first group d-axis current detection value Id1, and calculate the first group q-axis current command value Iq1 ＊ and the first group q-axis current detection value Iq1, and calculate the second group d-axis current command value Id2 ＊ and the second group d-axis current detection value Id2, and calculate the second group q-axis current command value Iq2 ＊ The current control unit 53 calculates the second group q-axis current deviation between the second group q-axis current detection value Iq1 and the second group q-axis current detection value Iq2. The current control unit 53 performs proportional and integral control calculations on the current deviation of each group to calculate the first group d-axis voltage command value Vd1. ＊ and the first group q-axis voltage command value Vq1 ＊ and the second group d-axis voltage command value Vd2 ＊and second group q-axis voltage command value Vq2 ＊ and calculate.

[0032] The two-phase to three-phase converter 54 converts the first group d-axis voltage command value Vd1 ＊ and the first group q-axis voltage command value Vq1 ＊ Based on this, the first group three-phase voltage command value Vu1 in the stationary coordinate system is calculated. ＊ , Vv1 ＊ and Vw1 ＊ is calculated, and the second group d-axis voltage command value Vd2 ＊ and the second group q-axis voltage command value Vq2 ＊ Based on this, the second group three-phase voltage command value Vu2 in the stationary coordinate system is calculated. ＊ , Vv2 ＊ and Vw2 ＊ The three-phase voltage command values ​​of each group calculated by the two-phase to three-phase conversion unit 54 are output to the PWM signal generation unit 56. ＊ is the voltage command value of the U phase of the first group, and the V phase voltage command value of the first group Vv1 ＊ is the voltage command value of the V phase of the first group, and the W phase voltage command value of the first group Vw1 ＊ is the voltage command value of the W phase of the first group. ＊ is the voltage command value of the U phase of the second group, and the V phase voltage command value of the second group Vv2 ＊ is the voltage command value of the V phase of the second group, and the W phase voltage command value of the second group Vw2 ＊ is the voltage command value of the W phase of the second group.

[0033] The carrier wave generator 55 receives the stator temperature Tst, the rotor temperature Trt, the first carrier frequency fc1, and the second carrier frequency fc2, and generates the first triangular wave carrier wave e1 and the second triangular wave carrier wave e2 based on the relationship between the stator temperature Tst and the rotor temperature Trt and the respective threshold temperatures. The stator temperature is the temperature of the stator windings. The temperature of the stator windings can be calculated using the thermistor that serves as the temperature detector 22.

[0034] Furthermore, the temperature detection unit 22 may use a thermocouple instead of a thermistor to calculate the temperature of the stator winding, and the calculation can also be based on a thermal circuit and losses in the rotating electric machine 2. If the rotating electric machine 2 is a permanent magnet rotating electric machine, the rotor temperature is the temperature of the permanent magnet, and if the rotating electric machine 2 is an induction rotating electric machine, it is the temperature of the rotor bars or end rings. The temperature of the permanent magnet can be calculated using the induced voltage obtained from the rotating electric machine 2. When the temperature of the permanent magnet changes, the magnetic force of the permanent magnet changes, and therefore the induced voltage of the rotating electric machine 2 also changes. Therefore, by knowing in advance the correspondence between the temperature of the permanent magnet and the induced voltage, the temperature of the permanent magnet can be calculated using the induced voltage of the rotating electric machine 2.

[0035] To calculate the temperature of the permanent magnets, rotor bars, or end rings, a thermocouple may be used as the temperature detection unit 22, or a slip ring may be used to attach the thermocouple to the rotor. If a slip ring is not used, the rotor temperature can be calculated by emitting and acquiring the signal from the thermocouple as a radio wave signal. Alternatively, the rotor temperature can be calculated from the thermal circuit and losses in the rotating electric machine 2.

[0036] The carrier frequency is the frequency of the triangular wave carrier wave in one electrical angle cycle. For example, the first group carrier frequency is the frequency of the first group triangular wave carrier wave e1 in one electrical angle cycle, and the second group carrier frequency is the frequency of the second group triangular wave carrier wave e2 in one electrical angle cycle. The carrier wave generation unit 55 calculates the phase difference between the first group triangular wave carrier wave e1 and the second group triangular wave carrier wave e2 based on the magnitude relationship between the stator temperature Tst and a predetermined stator temperature threshold and the magnitude relationship between the rotor temperature Trt and the rotor temperature threshold. The carrier wave generation unit 55 then outputs the first group triangular wave carrier wave e1 and the second group triangular wave carrier wave e2 based on the calculated phase difference between the first group triangular wave carrier wave e1 and the second group triangular wave carrier wave e2, the first group carrier frequency fc1, and the second group carrier frequency fc2.

[0037] The carrier wave generating unit 55 may have a triangular wave carrier phase difference map in which the phase differences of the triangular wave carriers are registered in association with the stator temperature and the rotor temperature. In this case, the carrier wave generating unit 55 identifies the triangular wave carriers of each group by searching the triangular wave carrier phase difference map using the stator temperature and the rotor temperature.

[0038] The PWM signal generator 56 converts the first group three-phase voltage command value Vu1 generated by the two-phase to three-phase converter 54 into ＊ , Vv1 ＊ and Vw1 ＊ and the second group three-phase voltage command value Vu2 ＊ , Vv2 ＊ and Vw2 ＊ The PWM signal generator 56 calculates on / off control signals for each switching element included in the first group power conversion circuit 32 and the second group power conversion circuit 42 based on the first group triangular wave carrier wave e1 and the second group triangular wave carrier wave e2 generated by the carrier wave generator 55 and the DC bus voltage Vpn. The PWM signal generator 56 compares the three-phase voltage command value with the triangular wave carrier wave using a comparator, determines the on / off of the switching elements based on the comparison result, and generates on / off control signals for performing switching operation with the determined on / off. The on / off control signals include first group on / off control signals UH1, UL1, VH1, VL1, WH1, and WL1 output to the first group power conversion circuit 32, and second group on / off control signals UH2, UL2, VH2, VL2, WH2, and WL2 output to the second group power conversion circuit 42.

[0039] The control unit 5 controls the on / off operation of the switching elements 321 to 326 using on / off control signals UH1, UL1, VH1, VL1, WH1, and WL1 sent to the first group power conversion circuit 32, and controls the on / off operation of the switching elements 421 to 426 using on / off control signals UH2, UL2, VH2, VL2, WH2, and WL2 sent to the second group power conversion circuit 42. The control unit 5 controls the switching operation of each switching element included in the power conversion circuit of each group to convert DC power input from the DC power supply 7 into AC power and supplies the converted AC power to the rotating electric machine 2. Furthermore, the control unit 5 controls the switching operation of each switching element included in the power conversion circuit of each group to charge the DC power supply 7 with regenerative power generated by the rotating electric machine 2 in a regenerative state.

[0040] 3 is a cross-sectional view showing a permanent magnet synchronous rotating electric machine, showing a cross section of the permanent magnet synchronous rotating electric machine cut along a plane perpendicular to the axial direction. In the rotating electric machine drive device 1, the rotating electric machine 2 may be a permanent magnet synchronous rotating electric machine. As shown in FIG. 3, the permanent magnet synchronous rotating electric machine has windings 202 on a stator 201 and permanent magnets 212 on a rotor 211. In FIG. 3, the permanent magnet synchronous rotating electric machine has 6 poles and 36 slots and has distributed winding with two per pole per phase.

[0041] In the per pole per phase (2) configuration, there are two slots per pole per phase. The windings of the stator 201 are composed of multiple groups of windings. Also, different groups of windings may be configured in the same slot. The permanent magnets 212 of the rotor 211 are configured to be arranged in a V-shape across two layers. By arranging the permanent magnets in two layers, the permanent magnets 212 on the inner diameter side of the rotor 211 are located farther away from the stator windings. This makes it possible to reduce the effects of harmonic magnetic flux caused by the carrier of the stator winding. Furthermore, eddy currents due to harmonic magnetic flux are reduced, thereby reducing eddy current loss.

[0042] FIG. 4 is a cross-sectional view of an induction rotating electric machine, showing a cross section of the induction rotating electric machine cut along a plane perpendicular to the axial direction. In the rotating electric machine drive device 1, the rotating electric machine 2 may be an induction rotating electric machine. As shown in FIG. 4, the induction rotating electric machine has a winding 202 on a stator 201 and rotor bars 213 on a rotor 211. The rotor bars 213 are short-circuited at both axial ends by end rings. In the induction rotating electric machine, the rotating magnetic field generated by the stator winding interlinks with the rotor 211, causing an induced current to flow in the rotor bars 213, generating torque and causing rotation. The rotor bars 213 may be circular, elliptical, or have a double-cage shape with two rotor bar slots in the radial direction. In a double-cage shape, the rotor bars 213 on the inner diameter side of the rotor 211 are located farther away from the stator winding, thereby reducing the influence of harmonic magnetic flux caused by the carriers in the stator winding.

[0043] FIG. 5 is a cross-sectional view showing the first and second group winding configurations for a per-pole, per-phase (2) configuration. The slot spacing for the stator windings for a per-pole, per-phase (2) configuration is an electrical angle θ = 180 / (3 × 2) = 30 degrees. The first group of windings is U1, V1, and W1, and the second group of windings is U2, V2, and W2. As shown in FIG. 5, the first and second groups of windings are wound with an electrical angle θ = 30 degrees offset. By arranging multiple groups of windings within one pole, harmonics can be canceled out between the groups, resulting in reduced loss and vibration. Furthermore, the multiple-group configuration provides redundancy in case one system fails. Also, Figure 5 shows a cross section per pole, and in each group, upward current flow is positive for the U-phase winding, upward current flow is positive for the V-phase winding, and downward current flow is positive for the W-phase winding.

[0044] Figure 6 is a cross-sectional view showing the first and second group winding configurations for each pole and phase (4). The slot spacing of the stator winding for each pole and phase (4) is an electrical angle θ = 180 / (3 x 4) = 15 degrees. The first group of windings are U1, V1, and W1, and the second group of windings are U2, V2, and W2. As shown in Figure 6, the first group of windings and the second group of windings are wound with an electrical angle θ of 30 degrees, which corresponds to two slots.

[0045] In the four-per-pole-per-phase configuration, the number of slots per pole per phase is four. In the four-system configuration with up to four groups per pole per phase (four), the windings in each group are wound with a shift of 15 degrees electrical angle θ, which corresponds to one slot. In the rotating electric machine drive device 1, the more systems there are, the more finely the phase difference of the carrier wave between each group can be shifted, enabling more precise reduction of harmonic magnetic flux, resulting in lower loss and vibration.

[0046] FIG. 7 is a graph showing the amplitude versus phase of the phase currents of the first and second groups. In FIG. 7, I1 indicates the relationship of the phase current of the first group versus the electrical angle, and I2 indicates the relationship of the phase current of the second group versus the electrical angle. The control unit 5 controls the amplitudes of the phase currents of the first and second groups output from the power conversion circuits of the respective groups so that they are equal. Furthermore, the current phase difference Δ12 between the phase currents of the first and second groups is controlled to be an electrical angle of 30 degrees. The control unit 5 controls the phase difference of the currents flowing between the first and second groups so that it is equal to the spatial phase difference, which is the winding spacing between the first and second groups, thereby canceling out the harmonic components of the first and second groups.

[0047] For the rotating electric machine 2 in which the first and second groups of windings are wound at an interval of 30 degrees electrical angle, the control unit 5 controls the first and second groups so that the current amplitudes are equal and so that the current phase difference between the first and second groups is 30 degrees electrical angle. As a result, the rotating electric machine drive device 1 can eliminate torque ripple and electromagnetic excitation force of 6f, which is a component six times the fundamental frequency f, and can reduce vibration.

[0048] Furthermore, since an electrical angle of 30 degrees corresponds to an electrical angle of 180 degrees for the 6f component, the torque ripple of the 6f component generated in the first system and the torque ripple of the 6f component generated in the second system are in an inverted phase relationship. This makes it possible to eliminate the torque ripple of the 6f component. Furthermore, since the magnetic flux is also canceled out in the same way, eddy currents caused by harmonic magnetic flux are reduced, making it possible to reduce loss.

[0049] 8 is a waveform diagram showing the first group of carrier waves and the second group of carrier waves. In FIG. 8, triangular wave A is the first group of triangular wave carrier waves, and triangular wave B is the second group of triangular wave carrier waves. The control unit 5 generates triangular waves based on the carrier frequencies of each group. For example, when performing synchronous control in which the carrier frequency is an integer multiple of the fundamental wave frequency f, the control unit 5 generates the first group of triangular wave carrier waves, which are triangular wave A, and the second group of triangular wave carrier waves, which are triangular wave B. For example, in one electrical angle cycle, there are nine cycles of triangular waves A and B, resulting in nine synchronous pulses.

[0050] Furthermore, the control unit 5 may perform asynchronous control in which the carrier frequency is not an integer multiple of the fundamental wave frequency f. Even in the case of asynchronous control, the control unit 5 controls the carrier wave phase difference ΔAB of each group to be switched based on the temperature of the stator and the temperature of the rotor.

[0051] FIG. 9 is a waveform diagram emphasizing the phase difference between the first and second carrier waves by expanding the phase range, and is an enlarged version of the waveforms in FIG. 8 . In FIG. 9 , triangular wave A is the first triangular wave carrier wave, and triangular wave B is the second triangular wave carrier wave. The control unit 5 may perform either synchronous control or asynchronous control to control the carrier phase difference ΔAB between the first and second carrier waves. The carrier phase difference ΔAB between the first and second carrier waves in FIG. 9 represents the phase converted into one cycle of the rotating electric machine 2. Furthermore, since there are nine synchronous pulses, one cycle of the carrier wave is an electrical angle θ = 360 / 9 = 40 degrees. The phase difference ΔAB between the carrier waves of each group is controlled as an angle converted into one cycle of the carrier wave.

[0052] When the control unit 5 controls the carrier wave phase difference ΔAB between the first and second groups to be 360 ​​degrees, the electrical angle θ is shifted by 40 degrees in one cycle of the rotating electric machine 2. Furthermore, the rectangular wave voltage calculated based on the comparison result between the three-phase voltage command value and the triangular wave carrier wave contains harmonics other than the fundamental wave. The harmonic components caused by the carrier appear as sidebands of integer multiples of the carrier frequency fc. With respect to the fundamental wave frequency f, typical frequency components of the harmonics contained in the rectangular wave voltage waveform are fc±2f and 2fc±f.

[0053] Because these carrier-induced harmonic components appear in each group, the control unit 5 cancels out the carrier-induced harmonic magnetic flux by changing the carrier phase difference between each group. If the spatial phase difference between the first and second windings is 30 degrees and the time phase difference between the currents flowing through the first and second windings is 30 degrees, the sideband waves caused by the primary carrier have a phase difference of 30 + 2 × 30 = 90 degrees due to the spatial phase difference and time phase difference. The sideband waves caused by the primary carrier are added or subtracted by the second fundamental wave, and the second fundamental wave is in opposite phase to the fundamental wave. Therefore, the spatial phase is expressed as an additive equation.

[0054] Because there is a 90-degree phase difference between the spatial phase difference and the time phase difference, if the carrier wave phase difference between groups 1 and 2 is (90 + 180 x n) degrees, it is possible to cancel out the harmonic magnetic flux caused by the primary carrier between groups 1 and 2, where n is an integer. On the other hand, if the spatial phase difference between groups 1 and 2 of the windings is 30 degrees and the time phase difference between the currents flowing through groups 1 and 2 is 30 degrees, the sideband waves caused by the secondary carrier will have a phase difference of 30 - 30 = 0 degrees due to the spatial phase difference and the time phase difference.

[0055] In the sideband waves caused by the secondary carrier, the fundamental wave is added or subtracted, and the fundamental wave becomes positive phase. Therefore, the spatial phase is expressed as a subtraction equation. Since the spatial phase difference and the time phase difference result in a phase difference of 0 degrees, if the carrier phase difference between the first and second groups is set to (180 x n) degrees, it is possible to cancel out the harmonic magnetic flux caused by the secondary carrier of the first and second groups.

[0056] Because the rotor is located across the air gap from the stator, the influence of high-frequency components is reduced. Therefore, when the harmonic magnetic flux caused by the secondary carrier is attenuated, the harmonic magnetic flux caused by the primary carrier becomes dominant. On the other hand, because the stator is located near the winding that generates the magnetic flux, the harmonic magnetic flux caused by the secondary carrier becomes dominant.

[0057] FIG. 10 is a graph showing rotor loss versus the carrier wave phase difference between the first and second groups. As shown in FIG. 10 , rotor loss is minimized when the carrier wave phase difference between the first and second groups is (90 + 180 × n) degrees, where n is an integer. Rotor loss refers to loss generated in the rotor core, loss generated in the permanent magnets of a permanent magnet synchronous rotating electric machine, or loss generated in the rotor bars of an induction rotating electric machine. Setting the carrier wave phase difference between the first and second groups to (90 + 180 × n) degrees suppresses rotor temperature rise. For example, if the rotating electric machine 2 is a permanent magnet synchronous rotating electric machine, it is possible to suppress temperature rise in the permanent magnets, prevent demagnetization, and prevent torque reduction. Furthermore, if the rotating electric machine 2 is an induction rotating electric machine, it is also possible to suppress temperature rise in the rotor bars, preventing damage due to temperature rise in the rotor bars and increased loss in the rotor bars due to increased resistance.

[0058] FIG. 11 is a graph showing stator loss versus the carrier phase difference between groups 1 and 2. As shown in FIG. 11, stator loss is minimized when the carrier phase difference between groups 1 and 2 is (180×n) degrees, where n is an integer. Stator loss refers to loss that occurs in the stator core. When the carrier phase difference between groups 1 and 2 is set to (180×n) degrees, it is possible to suppress the rise in stator winding temperature. Suppressing the rise in stator winding temperature can prevent damage to the winding insulation coating.

[0059] Next, a method for driving a rotating electric machine according to the first embodiment will be described. Fig. 12 is a flowchart showing the method for driving a rotating electric machine according to the first embodiment. The control unit 5 determines whether the temperature of the rotor provided in the rotating electric machine 2 is higher than a threshold temperature (step ST1). If the rotor temperature is higher than the threshold temperature (step ST1; YES), the control unit 5 controls the carrier wave phase difference between the first and second groups to be (90 + 180 x n) degrees (step ST2), where n is an integer.

[0060] The rotor temperature is, for example, the temperature of the permanent magnets when the rotating electric machine 2 is a permanent magnet rotating electric machine, or the temperature of the rotor bars or end rings when the rotating electric machine 2 is an induction rotating electric machine. If the rotating electric machine 2 is a permanent magnet synchronous rotating electric machine, the threshold temperature corresponding to the rotor is set to a temperature lower than the temperature at which demagnetization of the permanent magnets occurs. The likelihood of demagnetization varies depending on the material of the permanent magnet. For example, permanent magnets containing large amounts of rare earth elements such as dysprosium or terbium have high coercive force and are less likely to demagnetize. However, permanent magnets containing large amounts of rare earth elements have the disadvantages of being expensive and having low residual magnetic flux density.

[0061] By switching the phase difference between multiple groups of carrier waves in response to the threshold temperature, the rotating electric machine drive device 1 can use low-cost permanent magnets with high residual magnetic flux density and reduced rare-earth element addition. Furthermore, if the rotating electric machine 2 is an induction rotating electric machine, the threshold temperature is set based on the designed resistance values ​​of the rotor bars and end rings. When the temperatures of both the rotor bars and end rings rise, the resistance values ​​of the rotor bars and end rings increase. As the resistance values ​​of the rotor bars and end rings increase, rotor loss increases. Therefore, the threshold temperature of the rotor can be set by setting upper limit resistance values ​​of the rotor bars and end rings during design. Setting the threshold temperature of the rotor in accordance with the upper limit resistance values ​​of the rotor bars and end rings can prevent an increase in rotor loss.

[0062] The threshold temperature may also be set according to the upper limit temperature of the bearings of the rotating electric machine 2. The upper limit operating temperature is set because a rise in temperature of the bearings causes the lubricant to deteriorate and shortens the lifespan. For this reason, the threshold temperature may be set to a value lower than the upper limit operating temperature of the bearings. When the rotor temperature is higher than the threshold temperature, the rotating electric machine drive device 1 controls the carrier wave phase difference between the first and second groups to be (90 + 180 × n) degrees, thereby reducing rotor loss and suppressing a rise in rotor temperature.

[0063] If the rotor temperature is equal to or lower than the threshold temperature (step ST1; NO), the control unit 5 determines whether the temperature of the stator provided in the rotating electric machine 2 is higher than the threshold temperature (step ST3). If the stator temperature is higher than the threshold temperature (step ST3; YES), the control unit 5 controls the carrier wave phase difference between the first and second groups to be (180 x n) degrees (step ST4). The stator temperature is the temperature of the stator winding. The threshold temperature corresponding to the stator is set according to the heat resistance temperature of the magnet wire. The heat resistance temperature of the magnet wire is set according to the heat resistance temperature of the material used for the insulating coating. For example, the threshold temperature of the stator temperature is set to a temperature lower than the heat resistance temperature of the magnet wire.

[0064] The stator temperature may be the temperature of the core, such as the teeth or core back, of the stator. By calculating the temperature of the stator winding using a thermal circuit network from the core temperature, it is possible to prevent deterioration of the insulating coating of the stator winding. If the stator temperature is higher than the threshold temperature, the control unit 5 controls the carrier wave phase difference between the first and second groups to be (180 x n) degrees, thereby reducing stator loss and suppressing temperature rise of the stator.

[0065] If the stator temperature is equal to or lower than the threshold temperature (step ST3; NO), the control unit 5 controls the loss to be minimized (step ST5). Here, the control unit 5 controls the carrier wave phase difference between the first and second groups so as to minimize the loss occurring in the rotating electric machine 2. For example, the control unit 5 stores in advance, as a map, the carrier wave phase difference between the first and second groups that minimizes the loss in the rotating electric machine 2 for each operating point in terms of the rotation speed and torque characteristics. The control unit 5 can switch the carrier wave phase difference between the first and second groups regardless of the operating point, even when minimizing the loss in the flowchart shown in FIG. 12. The series of processes shown in FIG. 12 are performed at regular time intervals. The map setting the carrier wave phase difference between the first and second groups that minimizes the loss in the rotating electric machine 2 can be calculated by finite element analysis or actual measurement using an actual device.

[0066] Fig. 13 is a waveform diagram showing a triangular carrier wave and phase voltage signal waves. In Fig. 13, the difference between the maximum and minimum values ​​of the triangular wave is the DC voltage Vpn. Also, the difference between the maximum value of the triangular wave and zero is the amplitude Vpn / 2. Meanwhile, the phase voltage signal waves are waveforms generated by the control unit 5 based on the three-phase voltage command values. The modulation factor is defined as the peak value C of the phase voltage signal waves relative to the amplitude of the triangular carrier wave. That is, modulation factor = phase voltage peak value / (Vpn / 2).

[0067] For example, when performing synchronous control in which the carrier frequency is an integer multiple of the fundamental frequency f, the control unit 5 can reduce harmonic components by aligning the carrier phase of the carrier and the fundamental phase to zero. This can reduce losses in the rotating electric machine 2 and suppress temperature rise. On the other hand, even when performing asynchronous control in which the carrier frequency is not an integer multiple of the fundamental frequency f, the control unit 5 controls the carrier phase difference of each group in accordance with the temperature of the rotating electric machine 2. This can reduce losses in the rotating electric machine 2 and suppress temperature rise.

[0068] FIG. 14 is a graph showing the harmonic voltage amplitude for the DC voltage Vpn in the carrier primary component versus the modulation factor. The frequency fc±2f component appears as the harmonic voltage for the DC voltage in the carrier primary component. FIG. 14 shows the characteristics of the frequency fc±2f component divided by the DC voltage Vpn versus the modulation factor. As shown in FIG. 14, since the DC voltage Vpn is constant, the larger the modulation factor, the larger the carrier primary component. In other words, the larger the modulation factor, the greater the loss due to the carrier primary component.

[0069] Because the carrier primary component has a lower frequency than the carrier secondary component, it also affects the rotor, which is located across the gap from the stator, in the rotating electric machine 2. For this reason, the control unit 5 can suppress the temperature rise of the rotor by controlling the modulation factor to be small. To reduce the modulation factor, the phase voltage peak value C can be reduced, and to reduce the phase voltage peak value C, the weak current can be increased. In other words, the current amplitude and current advance angle of the phase current can be increased.

[0070] FIG. 15 is a graph showing the harmonic voltage amplitude for the DC voltage Vpn in the carrier secondary component versus the modulation factor. The frequency 2fc±f component appears as the harmonic voltage for the DC voltage Vpn in the carrier secondary component. FIG. 15 shows the characteristics of the frequency 2fc±f component divided by the DC voltage Vpn versus the modulation factor. As shown in FIG. 15, the carrier secondary component is maximized at a modulation factor of 0.6. The carrier secondary component has a significant impact on losses generated in the stator winding or core. Therefore, the control unit 5 can suppress the temperature rise of the stator by controlling the modulation factor to reduce losses caused by the carrier secondary component.

[0071] 15, the tendency of the loss due to the secondary carrier changes at a modulation factor of 0.6, so the control unit 5 can control the modulation factor to be larger when the modulation factor is greater than 0.6. To increase the modulation factor, the phase voltage peak value C can be increased, and to increase the phase voltage peak value C, the weak current can be reduced. In other words, the current amplitude and current advance angle of the phase current can be reduced.

[0072] 16 is a graph showing carrier harmonic components appearing in the first and second groups with respect to frequency and rotation speed. In FIG. 16, the carrier frequency of the first group is fc1, and the carrier frequency of the second group is fc2. When the control unit 5 switches the carrier phase difference between the first and second groups in accordance with the temperature of the rotating electric machine 2, if the carrier frequencies of the first and second groups are made equal, the frequency components caused by the carrier will match. This makes it possible to cancel out the harmonic components caused by the carrier.

[0073] On the other hand, even when the carrier frequencies of Group 1 and Group 2 are different, it is possible to cancel out the harmonic components caused by the carrier by setting the carrier frequencies of Group 1 and Group 2 to predetermined values. For example, by controlling the carrier frequencies of Group 1 and Group 2 so as to satisfy fc1 + 2f = 2fc2 - f, the control unit 5 can cancel out the carrier primary sideband of Group 1 and the carrier secondary sideband of Group 2, thereby reducing carrier-induced loss.

[0074] When the temperature rise of the switching elements in each group of power conversion circuits differs, the control unit 5 reduces the switching loss of the switching element with the highest temperature by setting the carrier frequency of each group to a different value. Even when the carrier frequencies of each group are set to different values, the control unit 5 controls the carrier frequencies of the first and second groups so as to satisfy fc1 + 2f = 2fc2 - f, and controls the carrier phase difference between the first and second groups in accordance with the temperature of the rotating electric machine 2. This allows the rotating electric machine drive device 1 to selectively suppress temperature rise of the stator and rotor.

[0075] When the rotating electric machine 2 is a permanent magnet synchronous rotating electric machine, eddy currents are generated in the permanent magnets due to harmonic magnetic flux. The eddy currents generated in the permanent magnets depend on the carrier frequency and the thickness of the permanent magnet in the magnetization direction. The harmonic magnetic flux caused by the carrier secondary is a 2fc±f component, and the eddy currents generated in the permanent magnets are expressed as the square of the harmonic magnetic flux, and the eddy currents generated in the permanent magnets are a 4fc component. The 4fc component of the eddy currents generated in the permanent magnets is calculated as the sum of the products of the 2fc+f component and the 2fc-f component. In order to reduce the 4fc component of the eddy currents generated in the permanent magnets, the carrier frequency can be set taking into account the skin depth.

[0076] The carrier frequency of the power converter is fc, the thickness of the permanent magnet in the magnetization direction is W, and the relative permeability of the permanent magnet is μ ｒ The conductivity of the permanent magnet is σ, and the vacuum permeability is μ ０ In this case, in order to remove the 4fc component of the eddy current generated in the permanent magnet, the carrier frequency fc should be set to fc>4 / (πμ ｒ μ ０ σW ２ ) is determined so as to satisfy the relationship: By reducing a specific component or more of the eddy current components generated in the permanent magnet, the control unit 5 can more clearly identify losses caused by the carriers in the stator and rotor. Therefore, when the control unit 5 switches the carrier phase difference between the first and second groups, it can more effectively suppress temperature rises in areas where temperature rise suppression is desired.

[0077] If the semiconductor switching elements included in the power converter are elements using silicon carbide (SiC), it is possible to switch the carrier wave phase at high speed by taking advantage of the heat dissipation properties. The control unit 5 can more effectively suppress temperature rise at specific locations of the rotating electric machine 2 by switching the carrier wave phase difference between each group. A multilevel inverter may be used for the power converter. Even when a multilevel inverter is used, the control unit 5 can suppress temperature rise at specific locations of the rotating electric machine 2 by switching the carrier wave phase difference between each group.

[0078] Next, a hardware configuration for realizing the functions of the control unit 5 will be described. The current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, the two-phase to three-phase conversion unit 54, the carrier wave generation unit 55, and the PWM signal generation unit 56 included in the control unit 5 are realized by processing circuits. That is, the control unit 5 includes a processing circuit for executing each process from step ST1 to step ST5 shown in FIG. 12. The processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in a memory.

[0079] 17A is a block diagram showing a hardware configuration for realizing the functions of the control unit 5. Fig. 17B is a block diagram showing a hardware configuration for executing software for realizing the functions of the control unit 5. In Figs. 17A and 17B , the input interface 100 is an interface that relays signals output from, for example, the rotation angle sensor 21, the temperature detection unit 22, the rotating electric machine current detection unit 33, and the rotating electric machine current detection unit 43 to the control unit 5. The output interface 101 is an interface that relays on / off control signals output from the control unit 5 to the first group power conversion circuit 32 and the second group power conversion circuit 42.

[0080] 17A , the processing circuit 102 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The functions of the current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, the two-phase to three-phase conversion unit 54, the carrier wave generation unit 55, and the PWM signal generation unit 56 included in the control unit 5 may be realized by separate processing circuits, or these functions may be realized together by a single processing circuit.

[0081] 17B , the functions of the current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, the two-phase to three-phase conversion unit 54, the carrier wave generation unit 55, and the PWM signal generation unit 56 included in the control unit 5 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 104.

[0082] The processor 103 reads and executes programs stored in the memory 104 to realize the functions of the current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, the two-phase to three-phase conversion unit 54, the carrier wave generation unit 55, and the PWM signal generation unit 56 included in the control unit 5. For example, the control unit 5 includes a memory 104 for storing programs that, when executed by the processor 103, result in the processing of steps ST1 to ST5 shown in FIG. 12 being executed. These programs cause a computer to execute the procedures or methods of the processing performed by the control unit 5. The memory 104 may be a computer-readable storage medium that stores programs for causing a computer to function as the control unit 5.

[0083] The memory 104 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically-EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD.

[0084] Some of the functions of the current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, the two-phase to three-phase conversion unit 54, the carrier wave generation unit 55, and the PWM signal generation unit 56 included in the control unit 5 may be realized by dedicated hardware, and the remaining functions may be realized by software or firmware. For example, the functions of the current command generation unit 51, the three-phase to two-phase conversion unit 52, the current control unit 53, and the two-phase to three-phase conversion unit 54 are realized by a processing circuit 102 that is dedicated hardware, and the functions of the carrier wave generation unit 55 and the PWM signal generation unit 56 are realized by the processor 103 reading and executing a program stored in a memory 104. In this way, the processing circuit can realize the above functions by hardware, software, firmware, or a combination of these.

[0085] As described above, the rotating electric machine drive device 1 according to the first embodiment drives the rotating electric machine 2 including a stator having three-phase stator windings driven by two systems, a first group and a second group, and a rotor that is a rotating body, and includes a first group power converter 3 and a second group power converter 4 that are provided corresponding to each group and convert DC power input from a DC power source 7 into phase currents and output the phase currents to the stator windings of the respective groups, and a control unit 5 that outputs control signals generated based on a carrier wave to control the first group power converters 3 and the second group power converters 4 and switches the phase of the carrier wave in each group when the temperature of a portion of the rotating electric machine 2 is higher than a threshold temperature. By switching the phase of the carrier wave in each group when the temperature of a portion of the rotating electric machine 2 is higher than the threshold temperature, the rotating electric machine drive device 1 can reduce losses generated in each portion of the rotating electric machine 2 and suppress temperature increases in portions that exceed the threshold temperature.

[0086] In the rotating electric machine drive device 1 according to the first embodiment, when the temperature of the stator of the rotating electric machine 2 is higher than the threshold temperature or when the temperature of the rotor is higher than the threshold temperature, the control unit 5 changes the phase difference of the carrier waves in each group. This enables the rotating electric machine drive device 1 to reduce losses occurring in each part of the rotating electric machine 2 and suppress temperature increases in parts that exceed the threshold temperature.

[0087] In the rotating electric machine drive device 1 according to the first embodiment, the rotating electric machine 2 is a multiple rotating electric machine having three-phase stator windings driven by two systems, group 1 and group 2. When the temperature of the stator of the rotating electric machine 2 is higher than a threshold temperature or when the temperature of the rotor is higher than a threshold temperature, the control unit 5 changes the phase difference of the carrier waves in each group. This enables the rotating electric machine drive device 1 to reduce losses occurring in each part of the rotating electric machine 2 and suppress temperature increases in parts that exceed the threshold temperature.

[0088] In the rotating electric machine drive device 1 according to the first embodiment, when the temperature of the stator is lower than the threshold temperature and the temperature of the rotor is lower than the threshold temperature, the control unit 5 sets the phase difference of the carrier waves in each group so as to minimize loss in the rotating electric machine 2. This enables the rotating electric machine drive device 1 to reduce loss occurring in each part of the rotating electric machine 2 and suppress temperature rises in parts that exceed the threshold temperature.

[0089] In the rotating electric machine drive device 1 according to the first embodiment, when synchronous control is performed in which the carrier frequency of the carrier wave is an integer multiple of the fundamental wave frequency, the control unit 5 aligns the phase of the carrier wave and the phase of the fundamental wave to 0. This makes it possible to reduce harmonic components, and therefore the rotating electric machine drive device 1 can reduce losses in the rotating electric machine 2 and suppress temperature increases.

[0090] In the rotary electric machine drive device 1 according to the first embodiment, the first and second groups of stator windings are configured with windings spaced apart by an electrical angle of 30 degrees. Since multiple groups of windings can be arranged within one pole, the rotary electric machine drive device 1 can cancel out harmonics between the groups, thereby achieving low loss and low vibration.

[0091] In the rotary electric machine drive device 1 according to the first embodiment, the control unit 5 controls the phase current output from the first group power converter 3 to the first group stator winding and the phase current output from the second group power converter 4 to the second group stator winding so that the current amplitudes are equal, and controls so that the current phase difference between the first group and the second group is an electrical angle of 30 degrees. This enables the rotary electric machine drive device 1 to reduce losses occurring in each portion of the rotary electric machine 2 and suppress temperature rises in portions that exceed a threshold temperature.

[0092] The rotary electric machine drive device 1 according to the first embodiment includes a first group power converter 3 that outputs a phase current to a first group of stator windings, and a second group power converter 4 that outputs a phase current to a second group of stator windings. A control unit 5 controls the carrier frequencies of the first group and the second group to be equal. This enables the rotary electric machine drive device 1 to reduce losses occurring in each portion of the rotary electric machine 2 and suppress temperature increases in portions that exceed a threshold temperature.

[0093] In the rotating electric machine drive device 1 according to the first embodiment, when the rotor temperature is higher than the threshold temperature and n is an integer, the control unit 5 controls the phase difference between the carrier waves of groups 1 and 2 to be (90 + 180 × n) degrees. This enables the rotating electric machine drive device 1 to suppress an increase in the rotor temperature.

[0094] In the rotary electric machine drive device 1 according to the first embodiment, when the rotor temperature is higher than the threshold temperature, the control unit 5 increases the current amplitude and current advance angle of the phase current output from the first group power converter 3 to the first group of stator windings and the phase current output from the second group power converter 4 to the second group of stator windings. This enables the rotary electric machine drive device 1 to suppress an increase in the stator temperature.

[0095] In the rotating electric machine drive device 1 according to the first embodiment, when the temperature of the stator is higher than the threshold temperature and n is an integer, the control unit 5 controls the phase difference of the carrier waves between the first and second groups to be (180×n) degrees. This enables the rotating electric machine drive device 1 to suppress an increase in the stator temperature.

[0096] In the rotary electric machine drive device 1 according to the first embodiment, when the stator temperature is higher than the threshold temperature and the modulation factor is higher than the threshold, the control unit 5 reduces the current amplitude and current advance angle of the phase currents output from the power converters 3 and 4 in the first and second groups. This enables the rotary electric machine drive device 1 to suppress an increase in the stator temperature.

[0097] In the rotary electric machine drive device 1 according to the first embodiment, the threshold value for the modulation factor is 0.6. The rotary electric machine drive device 1 controls the modulation factor using this threshold value to reduce losses caused by the secondary carrier component, thereby suppressing the temperature rise of the stator.

[0098] The rotary electric machine drive device 1 according to the first embodiment includes a first group power converter 3 that outputs a phase current to a first group of stator windings, and a second group power converter 4 that outputs a phase current to a second group of stator windings. A control unit 5 controls the carrier frequencies of the first and second groups to satisfy the relationship fc1 + 2f = 2fc2, where f is the fundamental frequency of the rotary electric machine 2, fc1 is the carrier frequency of the carrier wave of the first group power converter 3, and fc2 is the carrier frequency of the carrier wave of the second group power converter 4. This allows the rotary electric machine drive device 1 to selectively suppress a temperature rise in the stator.

[0099] In the rotary electric machine drive device 1 according to the first embodiment, the rotary electric machine 2 has a permanent magnet as a rotor. The control unit 5 calculates the carrier frequency as fc (Hz), the thickness of the permanent magnet in the magnetization direction as W (m), and the relative permeability of the permanent magnet as μ ｒ The conductivity of the permanent magnet is σ (S / m), and the vacuum permeability is μ ０ In this case, the carrier frequency is fc>4 / (πμ ｒ μ ０ σW ２ ) is satisfied. The rotating electric machine drive device 1 reduces eddy current components generated in the permanent magnets above a specific level, thereby making the losses caused by the carriers in the stator and rotor more apparent. Therefore, when the carrier phase difference between the first and second groups is switched, it is possible to more effectively suppress temperature rise in areas where temperature rise should be suppressed.

[0100] In the rotating electric machine drive device 1 according to the first embodiment, the first group power converter 3 and the second group power converter 4 have an inverter circuit in which six semiconductor switching elements using silicon carbide are connected in a full bridge. The rotating electric machine drive device 1 controls this inverter circuit to switch the carrier phase difference between the groups, thereby more effectively suppressing temperature rises at specific locations of the rotating electric machine 2.

[0101] In the rotating electric machine drive method according to the first embodiment, the control unit 5 controls the phase difference of the carrier waves between the first and second groups to be (90 + 180 × n) degrees when the rotor temperature is higher than a threshold temperature and n is an integer, controls the phase difference of the carrier waves between the first and second groups to be (180 × n) degrees when the stator temperature is higher than the threshold temperature and n is an integer, and sets the phase difference of the carrier waves in each group to minimize loss in the rotating electric machine 2 when the stator temperature is lower than the threshold temperature and the rotor temperature is lower than the threshold temperature. By having the control unit 5 execute the above method, it is possible to realize a rotating electric machine drive device 1 that can reduce loss occurring in each portion of the rotating electric machine 2 and suppress temperature rises in portions that exceed the threshold temperature.

[0102] Various aspects of the present disclosure are summarized below as appendices.

[0103] (Supplementary Note 1) A rotary electric machine drive device for driving a rotary electric machine including a stator having multiple groups of stator windings of three or more phases, and a rotor which is a rotating body, comprising: multiple groups of power converters provided corresponding to the respective groups, each converting DC power input from a power source into a phase current and outputting the phase current to the stator windings of the respective groups; and a control unit that outputs a control signal generated based on a carrier wave to control the power converters of the respective groups, and switches the phase of the carrier wave in each group when the temperature of a part of the rotary electric machine is higher than a threshold temperature. (Supplementary Note 2) The rotary electric machine drive device according to Supplementary Note 1, characterized in that the control unit changes the phase difference of the carrier wave in each group when the temperature of the stator of the rotary electric machine is higher than the threshold temperature or the temperature of the rotor is higher than the threshold temperature. (Supplementary Note 3) The rotating electric machine drive device according to Supplementary Note 1, wherein the rotating electric machine is a multiple rotating electric machine having three-phase stator windings driven by two systems, a first group and a second group, and the control unit changes the phase difference of the carrier wave in each group when the temperature of the stator of the rotating electric machine is higher than the threshold temperature or the temperature of the rotor is higher than the threshold temperature. (Supplementary Note 4) The rotating electric machine drive device according to Supplementary Note 3, wherein the control unit sets the phase difference of the carrier wave in each group so as to minimize loss in the rotating electric machine when the temperature of the stator is lower than the threshold temperature and the temperature of the rotor is lower than the threshold temperature. (Supplementary Note 5) The rotating electric machine drive device according to any one of Supplementary Notes 2 to 4, wherein the control unit aligns the phase of the carrier wave and the phase of the fundamental wave to 0 when synchronous control is performed in which the carrier frequency of the carrier wave is an integer multiple of the fundamental wave frequency. (Supplementary Note 6) The rotary electric machine drive device according to Supplementary Note 3, wherein the first and second groups of stator windings are configured with windings spaced apart by an electrical angle of 30 degrees.(Supplementary Note 7) The rotary electric machine drive device according to Supplementary Note 6, wherein the control unit controls the phase current output from the power converter of the first group to the stator winding of the first group and the phase current output from the power converter of the second group to the stator winding of the second group so that current amplitudes are equal, and controls so that the current phase difference between the first and second groups is 30 degrees electrical angle. (Supplementary Note 8) The rotary electric machine drive device according to Supplementary Note 3, wherein the power converters are the power converter of the first group that outputs a phase current to the stator winding of the first group and the power converter of the second group that outputs a phase current to the stator winding of the second group, and the control unit controls so that the carrier frequencies are equal between the first and second groups. (Supplementary Note 9) The rotary electric machine drive device according to Supplementary Note 8, wherein the control unit controls so that the phase difference between the carrier waves of the first and second groups is (90 + 180 × n) degrees when the temperature of the rotor is higher than the threshold temperature and n is an integer. (Supplementary Note 10) The rotating electric machine drive device according to Supplementary Note 9, wherein the control unit increases the current amplitude and current advance angle of the phase current output from the power converter of the first group to the stator winding of the first group and the phase current output from the power converter of the second group to the stator winding of the second group when the temperature of the rotor is higher than the threshold temperature. (Supplementary Note 11) The rotating electric machine drive device according to Supplementary Note 8, wherein the control unit controls the phase difference of the carrier wave between the first group and the second group to be (180 x n) degrees when the temperature of the stator is higher than the threshold temperature and n is an integer. (Supplementary Note 12) The rotating electric machine drive device according to Supplementary Note 11, wherein the control unit decreases the current amplitude and current advance angle of the phase current output from the power converter of the first group and the second group when the temperature of the stator is higher than the threshold temperature and a modulation factor is larger than a threshold. (Supplementary Note 13) The rotating electric machine drive device according to Supplementary Note 12, wherein the threshold for the modulation factor is 0.6.(Supplementary Note 14) The rotating electric machine drive device according to Supplementary Note 3, wherein the power conversion circuit comprises a first group of the power converters that outputs a phase current to a first group of the stator windings and a second group of the power converters that outputs a phase current to a second group of the stator windings, and the control unit controls the carrier frequencies of the first and second groups to satisfy the relationship fc1 + 2f = 2fc2, where f is a fundamental frequency of the rotating electric machine, fc1 is a carrier frequency of the carrier wave of the power converters of the first group, and fc2 is a carrier frequency of the carrier wave of the power converters of the second group. (Supplementary Note 15) The rotating electric machine has a permanent magnet as the rotor, and the control unit controls the carrier frequency to be fc (Hz), W (m) is a thickness of the permanent magnet in the magnetization direction, and μ is a relative permeability of the permanent magnet. ｒ The conductivity of the permanent magnet is σ (S / m), and the vacuum permeability is μ ０ In this case, the carrier frequency is fc>4 / (πμ ｒ μ ０ σW ２(Supplementary Note 16) The rotating electric machine drive device according to any one of Supplementary Note 1 to Supplementary Note 15, wherein the power conversion circuit has an inverter circuit in which six semiconductor switching elements using silicon carbide are connected in a full bridge configuration per group. (Supplementary Note 17) A method for driving a rotating electric machine using a rotating electric machine drive device, the method comprising: a stator having multiple groups of stator windings of three or more phases; and a rotor which is a rotating body; a multiple groups of power converters provided corresponding to each group, converting DC power input from a power source into phase currents and outputting the phase currents to the stator windings of each group; and a control unit which outputs control signals generated based on carrier waves to control the power converters of each group, wherein the control unit: when the temperature of the rotor is higher than a threshold temperature and n is an integer, controls the phase difference of the carrier waves between the first and second groups to be (90 + 180 × n) degrees; when the temperature of the stator is higher than the threshold temperature and n is an integer, controls the phase difference of the carrier waves between the first and second groups to be (180 × n) degrees; and when the temperature of the stator is lower than the threshold temperature and the temperature of the rotor is lower than the threshold temperature, sets the phase difference of the carrier waves in each group so as to minimize loss in the rotating electric machine.

[0104] Any of the components of the embodiments may be modified or omitted.

[0105] A rotating electric machine drive device according to the present disclosure can be used, for example, in a power conversion device.

[0106] 1 Rotating electric machine drive device, 2 Rotating electric machine, 2a AC bus, 3 1st group power converter, 3a, 3b DC bus, 4 2nd group power converter, 5 Control unit, 6a, 6b Power switch, 7 DC power supply, 21 Rotation angle sensor, 22 Temperature detection unit, 31 1st group capacitor, 32 1st group power conversion circuit, 33, 43 Rotating electric machine current detection unit, 41 2nd group capacitor, 42 2nd group power conversion circuit, 51 Current command generation unit, 52 Three-phase to two-phase conversion unit, 53 Current control unit, 54 Two-phase to three-phase conversion unit, 55 Carrier wave generation unit, 56 PWM signal generation unit, 100 Input interface, 101 Output interface, 102 Processing circuit, 103 Processor, 104 Memory, 201 Stator, 202 Winding, 211 Rotor, 212 Permanent magnet, 213 Rotor bars, 321-326, 421-426 Switching elements.

Claims

1. A rotating electric machine drive device that drives a rotating electric machine having a stator with multiple groups of stator windings of three or more phases, and a rotor which is a rotating body, comprising: multiple groups of power converters provided corresponding to each group, which convert DC power input from a power source into phase current and output it to the stator windings of each group; and a control unit that outputs a control signal generated based on a carrier wave to control the power converters of each group, and switches the phase of the carrier wave in each group when the temperature of a part of the rotating electric machine is higher than a threshold temperature.

2. The rotating electric machine drive device according to claim 1, characterized in that the control unit changes the phase difference of the carrier waves in each group when the temperature of the stator of the rotating electric machine is higher than the threshold temperature or when the temperature of the rotor is higher than the threshold temperature.

3. The rotating electric machine drive device according to claim 1, characterized in that the rotating electric machine is a multiple rotating electric machine equipped with three-phase stator windings driven in two systems, group 1 and group 2, and the control unit changes the phase difference of the carrier wave in each group when the temperature of the stator of the rotating electric machine is higher than the threshold temperature or when the temperature of the rotor is higher than the threshold temperature.

4. The rotating electric machine drive device according to claim 3, characterized in that the control unit sets the phase difference of the carrier waves in each group so that losses in the rotating electric machine are minimized when the temperature of the stator is lower than the threshold temperature and when the temperature of the rotor is lower than the threshold temperature.

5. A rotating electric machine drive device as described in any one of claims 2 to 4, characterized in that when synchronous control is performed in which the carrier frequency of the carrier wave is an integer multiple of the fundamental wave frequency, the control unit aligns the phase of the carrier wave and the phase of the fundamental wave to 0.

6. The rotating electric machine drive device according to claim 3, characterized in that the first and second groups of stator windings are configured with windings spaced apart by an electrical angle of 30 degrees.

7. The rotating electric machine drive device according to claim 6, characterized in that the control unit controls the current amplitudes of the phase currents output from the power converter in group 1 to the stator winding in group 1 and the phase currents output from the power converter in group 2 to the stator winding in group 2 to be equal, and controls the current phase difference between group 1 and group 2 to be an electrical angle of 30 degrees.

8. The rotating electric machine drive device according to claim 3, characterized in that the power converters are a first group of power converters that output a phase current to a first group of stator windings, and a second group of power converters that output a phase current to a second group of stator windings, and the control unit controls the first group and the second group so that the carrier frequencies are equal to each other.

9. The rotating electric machine drive device according to claim 8, characterized in that the control unit controls the phase difference of the carrier wave between the first and second groups to be (90 + 180 x n) degrees when the rotor temperature is higher than the threshold temperature and n is an integer.

10. The rotating electric machine drive device according to claim 9, characterized in that, when the temperature of the rotor is higher than the threshold temperature, the control unit increases the current amplitude and current advance angle of the phase current output from the first group of the power converter to the first group of the stator windings and the phase current output from the second group of the power converter to the second group of the stator windings.

11. The rotating electric motor drive device according to claim 8, characterized in that the control unit controls the phase difference of the carrier wave between the first and second groups to be (180 x n) degrees when the temperature of the stator is higher than the threshold temperature and n is an integer.

12. The rotating electric machine drive device according to claim 11, characterized in that the control unit reduces the current amplitude and current advance angle of the phase currents output from the power converter in the first and second groups when the temperature of the stator is higher than the threshold temperature and the modulation rate is greater than a threshold.

13. The rotating electric machine drive device according to claim 12, characterized in that the threshold value for the modulation factor is 0.

6.

14. The rotating electric machine drive device according to claim 3, characterized in that the power converters are a first group of power converters that output a phase current to a first group of stator windings, and a second group of power converters that output a phase current to a second group of stator windings, and the control unit controls the carrier frequencies of the first and second groups so as to satisfy the relationship fc1 + 2f = 2fc2 - f, where f is the fundamental frequency of the rotating electric machine, fc1 is the carrier frequency of the carrier wave of the power converter of the first group, and fc2 is the carrier frequency of the carrier wave of the power converter of the second group.

15. The rotating electric machine has a permanent magnet as the rotor, and the control unit defines a carrier frequency as fc (Hz), a thickness of the permanent magnet in the magnetization direction as W (m), and a relative permeability of the permanent magnet as μ ｒ The electrical conductivity of the permanent magnet is σ (S / m), and the vacuum permeability is μ ０ In this case, the carrier frequency is fc>4 / (πμ ｒ μ ０ σ ２ 2. The rotating electric machine drive device according to claim 1, wherein the power converter is controlled so as to satisfy the relationship expressed by:

16. The rotating electric machine drive device according to claim 1, characterized in that the power converter has an inverter circuit in which six semiconductor switching elements using silicon carbide are connected in a full bridge configuration per group.

17. A method for driving a rotating electric machine using a rotating electric machine drive device comprising: a plurality of groups of power converters, each corresponding to one of the groups, converting DC power input from a power source into phase current and outputting the phase current to the stator winding of the respective groups; and a control unit that outputs a control signal generated based on a carrier wave to control the power converter of the respective groups, wherein the control unit: when the temperature of the rotor is higher than a threshold temperature and n is an integer, controls the phase difference of the carrier wave between the first and second groups to be (90 + 180 x n) degrees; when the temperature of the stator is higher than the threshold temperature and n is an integer, controls the phase difference of the carrier wave between the first and second groups to be (180 x n) degrees; and when the temperature of the stator is lower than the threshold temperature and the temperature of the rotor is lower than the threshold temperature, sets the phase difference of the carrier wave in each group so that loss in the rotating electric machine is minimized.

Images