Inverter control device, program, and inverter control method

Abstract

An inverter control device (80) includes first processing units (91, 92, 101-103) and second processing units (90, 93-96, 104). The first processing units perform a first process for, in the case of a first state, in which high-potential-side terminals of first and second upper arm switches (SUHa-SWHa, SUHb-SWHb) are electrically disconnected and low-potential-side terminals of first and second lower arm switches (SULa-SWLa, SULb-SWLb) are electrically connected in each phase, or a second state, in which the low-potential-side terminals of the first and second lower arm switches are electrically disconnected and the high-potential-side terminals of the first and second upper arm switches are electrically connected in each phase, controlling at least one of the first upper arm switches or the first lower arm switches. The second processing units perform a second process for controlling at least one of the second upper arm switches or the second lower arm switches during the execution of the first process. The first processing units perform a process for controlling the amplitude of AC current flowing in armature windings (51U-51W) as the first process. The second processing units perform a process for controlling the amplitude of AC current flowing in a second power storage unit (12) as the second process.

Description

Inverter control device, program, and inverter control method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-049979, filed on March 26, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an inverter control device, a program, and an inverter control method.

[0003] Conventionally, a system for controlling the drive of a rotating electric machine using two inverters has been known. In this system, a first inverter is connected to first ends of a multi-phase armature winding of the rotating electric machine, and a second inverter is connected to second ends of the armature winding. A first power storage unit is connected to the first inverter, and a second power storage unit is connected to the second inverter. By controlling the switching of the first and second inverters, an AC current is passed through the first and second power storage units, thereby performing temperature increase control to increase the temperatures of the first and second power storage units. An example of such a technology is disclosed in Patent Document 1.

[0004] Japanese Patent Application Laid-Open No. 2021-13225

[0005] When the temperature rise control is executed, an AC current also flows through the armature winding. In order to increase the degree of temperature rise of the first and second power storage units, it is conceivable to increase the amplitude of the AC current flowing through the first and second power storage units. However, in this case, the amplitude of the AC current flowing through the armature winding also increases. As a result, the rotating electric machine may overheat, which may reduce the reliability of the rotating electric machine.

[0006] The main object of the present disclosure is to provide an inverter control device, a program, and an inverter control method that can prevent a rotating electric machine from overheating when an alternating current is passed through first and second storage units to raise their temperature.

[0007] The present disclosure relates to an inverter control device that is applied to a system including: a rotating electric machine having a multi-phase armature winding; a first inverter having first upper arm switches and first lower arm switches connected in series for the same number of phases, with the series-connected body of the first upper and lower arm switches connected in parallel to a first power storage unit; and a second inverter having second upper arm switches and second lower arm switches connected in series for the same number of phases, with the series-connected body of the second upper and lower arm switches connected in parallel to a second power storage unit, wherein, in each phase, a low potential side terminal of the first upper arm switch and a high potential side terminal of the first lower arm switch are electrically connected to a first end of the armature winding; and a first processing unit that performs a first process to control at least one of the first upper and lower arm switches when the state is either a first state in which the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically disconnected in each phase and the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically connected in each phase, or a second state in which the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically disconnected in each phase and the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically connected in each phase; and a second processing unit that performs a second process to control at least one of the second upper and lower arm switches while the first process is being performed, wherein the first processing unit performs a process to control at least one of the first upper and lower arm switches so as to control the amplitude of the AC current flowing through the armature winding, The second processing unit performs, as the second process, a process of controlling at least one of the second upper and lower arm switches to control the amplitude of the AC current flowing through the second power storage unit.

[0008] The first processing unit executes the first process to control the amplitude of the current flowing through the armature winding. If the amplitude of the current flowing through the armature winding is reduced by the first process, the second processing unit executes the second process to compensate for the reduction. This prevents the amplitude of the current flowing through the armature winding from becoming excessively large while suppressing a reduction in the amplitude of the AC current flowing through the second power storage unit. As a result, the rotating electric machine can be prevented from overheating.

[0009] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an overall configuration diagram of a control system according to a first embodiment, Fig. 2 is a block diagram of temperature rise ripple processing, Fig. 3 is a diagram showing a setting mode of a target ripple current, Fig. 4 is a diagram showing a setting mode of the amplitude of the target ripple current, Fig. 5 is a diagram showing a setting mode of the amplitude of the target ripple current, Fig. 6 is a diagram schematically showing AC currents flowing through the armature winding and the first and second batteries according to a first comparative example, and Fig. 7 is a diagram showing AC currents flowing through the armature winding and the first and second batteries according to a second comparative example. 8 is a diagram schematically showing the AC current flowing through the armature winding and the first and second batteries according to the first embodiment; FIG. 9 is a flowchart showing the procedure for temperature rise ripple processing; FIG. 10 is a calculation result showing that the amplitude of the AC current flowing through the armature winding can be reduced while maintaining the amplitude of the AC current flowing through the first and second batteries; FIG. 11 is a calculation result showing that the amount of heat generation can be increased; and FIG. 12 is a diagram schematically showing the AC current flowing through the armature winding and the first and second batteries according to a modification of the first embodiment. 16 is a flowchart showing the procedure for temperature rise ripple processing according to the third embodiment; FIG. 17 is a diagram showing the setting of the duty ratio before the switching condition is satisfied; FIG. 18 is a diagram showing the setting of the duty ratio after the switching condition is satisfied; FIG. 19 is a diagram showing the carrier signal in the large heat generation mode according to the fourth embodiment; FIG. 20 is a diagram showing the carrier signal in the small heat generation mode; FIG. 21 is a flowchart showing the procedure for temperature rise ripple processing;25 is a diagram showing the overall configuration of a control system according to another embodiment; FIG. 26 is a diagram showing the overall configuration of a control system according to another embodiment; FIG. 27 is a diagram showing the overall configuration of a control system according to another embodiment; and FIG. 28 is a diagram showing the overall configuration of a control system according to another embodiment.

[0010] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0011] A first embodiment of a control device according to the present disclosure will be described below with reference to the drawings. The control device of the present embodiment is applied to a control system mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle.

[0012] As shown in FIG. 1 , the control system 10 includes a first battery 11 (corresponding to a "first power storage unit") and a second battery 12 (corresponding to a "second power storage unit"), which are DC power sources, a first inverter 20, a second inverter 30, and a rotating electric machine 40. Each of the batteries 11, 12 is, for example, a battery pack including a series connection of unit cells. The unit cell is a single battery cell or a series connection of multiple battery cells. The battery cell is, for example, a secondary battery such as a lithium-ion battery. In this embodiment, the rated voltage of each of the batteries 11, 12 is the same.

[0013] The first inverter 20 and the second inverter 30 are power conversion circuits that convert DC power into three-phase AC power and output it. The first inverter 20 includes a series connection of U-, V-, and W-phase first upper arm switches SUHa, SVHa, and SWHa and U-, V-, and W-phase first lower arm switches SULa, SVLa, and SWLa. A first battery 11 is connected in parallel to this series connection. The second inverter 30 includes a series connection of U-, V-, and W-phase second upper arm switches SUHb, SVHb, and SWHb and U-, V-, and W-phase second lower arm switches SULb, SVLb, and SWLb. A second battery 12 is connected in parallel to this series connection.

[0014] In this embodiment, each of the switches SUHa to SWLa and SUHb to SWLb is a voltage-controlled semiconductor switching element, more specifically, an IGBT. The high-potential terminal of each of the switches SUHa to SWLa and SUHb to SWLb is a collector, and the low-potential terminal is an emitter. A freewheel diode is connected in anti-parallel to each of the switches SUHa to SWLb. Specifically, U-, V-, and W-phase first upper-arm diodes DUHa, DVHa, and DWHa are connected in anti-parallel to the U-, V-, and W-phase first upper-arm switches SUHa, SVHa, and SWHa, respectively, and U-, V-, and W-phase first lower-arm diodes DULa, DVLa, and DWLa are connected in anti-parallel to the U-, V-, and W-phase first lower-arm switches SULa, SVLa, and SWLa, respectively. U, V, W-phase second upper-arm diodes DUHb, DVHb, DWHb are connected in anti-parallel to the U, V, W-phase second upper-arm switches SUHb, SVHb, SWHb, and U, V, W-phase second lower-arm diodes DULb, DVLb, DWLb are connected in anti-parallel to the U, V, W-phase second lower-arm switches SULb, SVLb, SWLb.

[0015] The emitters of the first lower arm switches SULa, SVLa, and SWLa of each phase and the emitters of the second lower arm switches SULb, SVLb, and SWLb of each phase are connected via a changeover switch 60 provided in the control system 10. The changeover switch 60 is, for example, a semiconductor switching element (e.g., an IGBT) or a mechanical relay. When the changeover switch 60 is turned on, the emitters of the lower arm switches SULa, SVLa, and SWLa of each phase of the first inverter 20 are electrically connected to the emitters of the lower arm switches SULb, SVLb, and SWLb of each phase of the second inverter 30. When the changeover switch 60 is turned off, the emitters of the lower arm switches SULa, SVLa, and SWLa of each phase of the first inverter 20 are electrically disconnected from the emitters of the lower arm switches SULb, SVLb, and SWLb of each phase of the second inverter 30.

[0016] On the other hand, the collectors of the first upper arm switches SUHa, SVHa, SWHa of each phase and the collectors of the second upper arm switches SUHb, SVHb, SWHb of each phase are not connected and are in an electrically isolated state (corresponding to the "first state").

[0017] The control system 10 includes a first capacitor 13 and a second capacitor 14. Each of the capacitors 13 and 14 functions as a smoothing capacitor. The first capacitor 13 is connected in parallel to the series connection of the first upper arm switches SUHa-SWHa and the first lower arm switches SULa-SWLa. The second capacitor 14 is connected in parallel to the series connection of the second upper arm switches SUHb-SWHb and the second lower arm switches SULb-SWLb.

[0018] The rotating electric machine 40 is an on-board main engine that serves as a power source for running the vehicle. The rotating electric machine 40 includes a rotor 41 and a stator 50. The rotor 41 is capable of transmitting power to the drive wheels of the vehicle. In this embodiment, the rotating electric machine 40 is a permanent magnet field type synchronous machine. The rotor 41 includes permanent magnets (e.g., neodymium magnets) as field poles 42.

[0019] The stator 50 includes a U-phase winding 51U, a V-phase winding 51V, and a W-phase winding 51W as armature windings. The phase windings 51U, 51V, and 51W are arranged at intervals of 120 electrical degrees on the stator core that constitutes the stator 50. The phase windings 51U, 51V, and 51W are open windings.

[0020] In each phase, the emitters of first upper switches SUHa, SVHa, SWHa and the collectors of first lower switches SULa, SVLa, SWLa are connected to first ends 51Ua, 51Va, 51Wa of the windings 51U, 51V, 51W, respectively. In each phase, the emitters of second upper switches SUHb, SVHb, SWHb and the collectors of second lower switches SULb, SVLb, SWLb are connected to second ends 51Ub, 51Vb, 51Wb of the windings 51U, 51V, 51W, respectively.

[0021] The control system 10 includes a current sensor 70, a rotation angle sensor 71, a voltage sensor 72, an inverter temperature sensor 73, a motor temperature sensor 74, and a battery temperature sensor 75 as sensors for detecting various state quantities in the control system 10.

[0022] The current sensor 70 detects the phase current flowing through each of the phase windings 51U, 51V, 51W. In this embodiment, the current sensor 70 is provided at one of both ends of each of the phase windings 51U, 51V, 51W closer to the first inverter 20. Note that the current sensor 70 may also be provided at one of both ends of each of the phase windings 51U, 51V, 51W closer to the second inverter 30.

[0023] The rotation angle sensor 71 is, for example, a resolver, and detects the electrical angle of the rotor 41. The voltage sensor 72 detects the voltage between the terminals of the first capacitor 13 and the second capacitor .

[0024] The inverter temperature sensor 73 detects the temperatures of the first and second inverters 20, 30. The inverter temperature sensor 73 detects, for example, the temperatures of the switches constituting the first and second inverters 20, 30. The motor temperature sensor 74 detects the temperature of the rotating electric machine 40. The motor temperature sensor 74 detects, for example, the temperatures of the armature windings (U-phase winding 51U, V-phase winding 51V, W-phase winding 51W).

[0025] The battery temperature sensor 75 detects the temperatures of the first battery 11 and the second battery 12. The detected values ​​of the sensors 70 to 75 are input to a control device 80 provided in the control system 10.

[0026] The control device 80 is an electronic control unit (ECU) that performs various controls of the control system 10, and includes a processor 81 and a storage unit 82 as hardware. In the control device 80, the processor 81 and the storage unit 82 are connected to each other via a communication bus 83.

[0027] The memory unit 82 includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the control device 80. The memory provides the processor 81 with a working area for temporary use when the processor 81 performs processing, for example. The memory includes, for example, a ROM or a RAM. The storage is a storage device for storing various programs and data to be read and executed by the processor 81, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or a flash memory. The storage stores program information and the like for the processing shown in FIGS. 2 and 9, which will be described later.

[0028] For example, program information stored on a non-transient physical recording medium is installed in the storage unit 82. The recording medium is, for example, a USB memory, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as over the air (OTA), is installed in the storage unit 82.

[0029] The control device 80 determines whether there is a temperature increase request for the first battery 11 and the second battery 12. If the control device 80 determines that there is a temperature increase request, the control device 80 performs temperature increase ripple processing to increase the temperatures of the batteries 11, 12 with the selector switch 60 turned on. The temperature increase ripple processing is a process in which, by controlling the switching of the first and second inverters 20, 30, an AC current is passed through the batteries 11, 12 to increase the heat generation amount [W] per unit time of each battery 11, 12.

[0030] The control device 80 may determine whether or not there is a temperature increase request based on, for example, the temperature Tbtr1 of the first battery 11 and the temperature Tbtr2 of the second battery 12 detected by the battery temperature sensor 75. Specifically, for example, the control device 80 may determine that there is a temperature increase request when it determines that the lower of the temperature Tbtr1 of the first battery 11 and the temperature Tbtr2 of the second battery 12, or a battery determination temperature Tbat which is the average value of the temperatures Tbtr1 and Tbtr2, is lower than the battery target temperature Tbtgt (0° C. or a temperature below 0° C.).

[0031] 2 is a block diagram of the temperature rise ripple process executed by the control device 80. The block diagram shown in FIG. 2 shows the process that is executed while the vehicle is stopped.

[0032] The ripple current command unit 90 calculates a target ripple current IM*, which is a target value of the AC current to be flowed through the second battery 12. In this embodiment, the waveform of the target ripple current IM* is a sine wave, as shown in FIG. 3 . In FIG. 3 , Ia indicates the amplitude of the target ripple current IM*, and Th indicates the period of the target ripple current IM*. The target ripple current IM* is calculated so that the positive target ripple current IM* and the negative target ripple current IM* are point-symmetric with respect to the timing at which the value of the target ripple current IM* changes from a non-zero value to zero (hereinafter referred to as the zero-crossing timing). As a result, the period from the first zero-crossing timing C1 to the second zero-crossing timing C2 of the target ripple current IM* is equal to the period from the second zero-crossing timing C2 to the third zero-crossing timing C3.

[0033] Furthermore, in one cycle Th of the target ripple current IM*, the area S1 of the first region and the area S2 of the second region are equal. The area S1 of the first region is an area surrounded by the positive target ripple current IM* and the time axis from the first zero-cross timing C1 to the second zero-cross timing C2 of the target ripple current IM* in one cycle Th of the target ripple current IM*. The area S2 of the second region is an area surrounded by the negative target ripple current IM* and the time axis from the second zero-cross timing C2 to the third zero-cross timing C3 of the target ripple current IM* in one cycle Th. By making the area S1 of the first region and the area S2 of the second region equal, the balance of the charge and discharge currents of the first battery 11 and the second battery 12 can be balanced in one cycle Th. Therefore, the difference between the terminal voltage of the first battery 11 and the terminal voltage of the second battery 12 can be prevented from increasing due to the temperature rise control.

[0034] In this embodiment, as shown in FIG. 4 , the ripple current command unit 90 calculates the battery temperature difference ΔTb by subtracting the battery determination temperature Tbat from the battery target temperature Tbtgt. The ripple current command unit 90 increases the amplitude Ia of the target ripple current IM* as the calculated battery temperature difference ΔTb increases. This reduces the time required for the temperatures of the batteries 11, 12 to reach the battery target temperature Tbtgt in the temperature rise ripple process. Note that the ripple current command unit 90 may increase the amplitude Ia in stages, for example, in two or three stages, as the battery temperature difference ΔTb increases.

[0035] 2 , the duty command unit 91 calculates a duty ratio Dtr (=Ton / Tsw), which is the ratio of the on-period Ton of the first upper arm switches SUHa, SVHa, and SWHa of each phase of the first inverter 20 to one switching period Tsw. The duty ratio Dtr is a parameter for controlling the amplitude of the current flowing through the phase windings 51U, 51V, and 51W during temperature rise control. In this embodiment, the duty ratio Dtr is greater than 0 and less than 1 when an AC current for temperature rise is flowing through each of the batteries 11 and 12.

[0036] In this embodiment, as shown in Fig. 5, the duty command unit 91 reduces the duty ratio Dtr as the armature winding temperature Tmr detected by the motor temperature sensor 74 increases. This prevents the armature winding from overheating when the temperature rise ripple process is performed. Note that the duty command unit 91 may reduce the duty ratio Dtr in stages, such as in two or three stages, as the armature winding temperature Tmr increases.

[0037] The first switch control unit 92 generates drive signals for each switch SUHa to SWLa of the first inverter 20 by PWM processing based on a magnitude comparison between the duty ratio Dtr (corresponding to a "modulated wave") calculated by the duty command unit 91 and the carrier signal SgC. The drive signals consist of switch on and off commands. In this embodiment, the carrier signal SgC is a triangular wave signal with equal increasing and decreasing speeds. In this embodiment, the maximum value Smax of the carrier signal SgC is 1, the minimum value Smin of the carrier signal is 0, and the median value of the carrier signal is 0.5.

[0038] Based on the generated drive signal, the first switch control unit 92 controls the charge / discharge current of the gates of the switches SUHa to SWLa of the first inverter 20. As a result, switching control of the switches SUHa to SWLa of the first inverter 20 is performed in accordance with the drive signal. In this embodiment, the first upper arm switches SUHa, SVHa, SWHa of each phase of the first inverter 20 are turned on and off synchronously, and the first lower arm switches SULa, SVLa, SWLa of each phase are turned on and off synchronously.

[0039] In addition, the first switch control unit 92 may keep the first lower arm switches SULa, SVLa, SWLa of each phase off during the temperature rise ripple process. In this embodiment, the duty command unit 91 and the first switch control unit 92 correspond to the “first processing unit.”

[0040] Here, if the duty ratio Dtr is set small in the duty command unit 91 in order to prevent the armature windings from overheating, a problem occurs in that the amplitude of the AC current flowing through each of the batteries 11 and 12 is reduced accordingly. A specific example to illustrate this problem will be described with reference to Figures 6 and 7. Figures 6 and 7 show the configuration of only one phase in the control system 10. For this reason, the symbols U, V, and W that identify the phase have been omitted from the symbols of each component.

[0041] Comparative Example 1 shown in Figure 6 illustrates a situation in which the armature windings overheat. To avoid this situation, Comparative Example 2 shown in Figure 7 illustrates a situation in which the AC current flowing through the armature windings is reduced to half that of Figure 6. By reducing the AC current to half, the AC current flowing through the second battery 12 is also reduced to half. As a result, the amount of heat generated per unit time is insufficient, which may result in a longer period of time until the temperatures of the batteries 11, 12 reach the battery target temperature Tbtgt.

[0042] Therefore, in this embodiment, as shown in Fig. 8, the control device 80 is provided with a configuration for reducing the amplitude of the AC current flowing through the armature windings while maintaining the amplitude of the AC current flowing through the second battery 12 at the amplitude of Comparative Example 1. More specifically, as shown in Fig. 2, the control device 80 is provided with a current correction unit 93, a current deviation calculation unit 94, and a current feedback control unit 95. The current correction unit 93, the current deviation calculation unit 94, and the current feedback control unit 95 are configured to compensate for the amount of heat generated per unit time by the first and second batteries 11, 12 while suppressing the occurrence of an overheated state in the armature windings.

[0043] The current correction unit 93 calculates the corrected target current Ib* (=IM* / Dtr, which corresponds to the "target value") by dividing the target ripple current IM* calculated by the ripple current command unit 90 by the duty ratio Dtr calculated by the duty command unit 91. Since "Dtr<1", the amplitude of the corrected target current Ib* is greater than the amplitude of the target ripple current IM*.

[0044] The current deviation calculation unit 94 calculates the zero-phase current Izr by adding the phase currents Iur, Ivr, and Iwr for three phases detected by the current sensor 70. The current deviation calculation unit 94 calculates the current deviation ΔI (=Ib*−Izr) between the corrected target current Ib and the calculated zero-phase current Izr.

[0045] The current feedback control unit 95 calculates a target ratio D* as a manipulated variable for feedback-controlling the calculated current deviation ΔI to zero. The target ratio D* is the ratio (=Tbon / Tsw) of the on-period Tbon of the second lower arm switches SULb, SVLb, SWLb of each phase of the second inverter 30 to one switching period Tsw. In this embodiment, the target ratio D* is a value greater than or equal to 0 and smaller than 1 when AC current for raising the temperature is passed through each of the batteries 11, 12. The feedback control used by the current feedback control unit 95 is, for example, proportional-integral control.

[0046] The second switch control unit 96 generates drive signals for the switches SUHb to SWLb of the second inverter 30 by PWM processing based on a magnitude comparison between the target ratio D* calculated by the current feedback control unit 95 and the carrier signal SgC. In this embodiment, the carrier signal SgC used by the second switch control unit 96 is the same as the carrier signal SgC used by the first switch control unit 92.

[0047] Based on the generated drive signal, the second switch control unit 96 controls the charge / discharge current of the gates of the switches SUHb to SWLb of the second inverter 30. As a result, switching control of the switches SUHb to SWLb of the second inverter 30 is performed in accordance with the drive signal. In this embodiment, the second upper arm switches SUHb, SVHb, and SWHb of each phase of the second inverter 30 are turned on and off synchronously, and the second lower arm switches SULb, SVLb, and SWLb of each phase are turned on and off synchronously.

[0048] The second switch control unit 96 may maintain the second upper arm switches SUHa, SVHa, and SWHa of each phase in the off state during the temperature rise ripple process. Furthermore, one switching period of each switch of the second inverter 30 may be different from one switching period of each switch of the first inverter 20.

[0049] In this embodiment, the ripple current command unit 90, the current correction unit 93, the current deviation calculation unit 94, the current feedback control unit 95, and the second switch control unit 96 correspond to a "second processing unit."

[0050] Fig. 9 shows a flowchart of the temperature rise ripple process executed by the control device 80. The process shown in Fig. 9 is repeatedly executed by the processor 81 of the control device 80, for example, at a predetermined control cycle.

[0051] In step S10, the ripple current command unit 90 calculates a target ripple current IM*.

[0052] In step S11, the duty command section 91 calculates the duty ratio Dtr.

[0053] In step S12, the current corrector 93 calculates a corrected target current Ib* based on the target ripple current IM* and the duty ratio Dtr calculated in steps S10 and S11.

[0054] In step S13, the current deviation calculation unit 94 and the current feedback control unit 95 calculate the target ratio D* based on the corrected target current Ib* calculated in step S12 and the zero-phase current Izr.

[0055] In step S14, the first switch control unit 92 controls the switching of the first inverter 20 based on the duty ratio Dtr calculated in step S11. In step S15, the second switch control unit 96 controls the switching of the second inverter 30 based on the target ratio D* calculated in step S14.

[0056] In this embodiment, the processes of steps S11 and S14 correspond to a "first process," and the processes of steps S10, S12, S13, and S15 correspond to a "second process."

[0057] 10 shows the calculation results of the transitions of the currents Im1 and Im2 flowing through the first and second batteries 11 and 12 and the current flowing through the armature windings in this embodiment and Comparative Example 1. Also, FIG. 11 shows the calculation results of the heat generation amount per unit time of the first and second batteries 11 and 12 in this embodiment and Comparative Example 1.

[0058] According to this embodiment, compared to Comparative Example 1, the current flowing through the armature windings can be reduced while maintaining the amplitude of the AC current flowing through the first and second batteries 11 and 12. As a result, the amount of heat generated per unit time of each battery 11 and 12 can be increased while suppressing the occurrence of overheating abnormalities in the armature windings. This, for example, eliminates the need to add a battery heating heater, or even if a battery heating heater is added, the maximum output power of the heater can be reduced. Note that in Comparative Example 1, the amount of heat generated is below the heat amount threshold Hth. In this case, for example, a battery heating heater would have to be added to the control system 10 to compensate for the insufficient heat source for heating the first and second batteries 11 and 12.

[0059] <Modification of First Embodiment> The temperature rise ripple process described in the first embodiment is effective even when the rated voltage of the first battery 11 is different from the rated voltage of the second battery 12. FIG. 12 illustrates a case where the rated voltage of the first battery 11 (400 V) is lower than the rated voltage of the second battery 12 (600 V). FIG. 13 illustrates a case where the rated voltage of the first battery 11 (400 V) is higher than the rated voltage of the second battery 12 (300 V). In the example illustrated in FIG. 13 , for example, the second upper arm switches SUHb, SVHb, and SWHb of the second inverter 30 are kept on, and the second lower arm switches SULb, SVLb, and SWLb of the second inverter 30 are kept off. Even in the examples illustrated in FIGS. 12 and 13 , the heat generation per unit time of the first and second batteries 11 and 12 can be compensated for while preventing the armature windings from overheating.

[0060] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, during temperature rise ripple processing, the continuation of switching control of a specific phase among the three phases of each inverter 20, 30 is prevented. This prevents the occurrence of overheating abnormalities in the switches of the specific phase.

[0061] Fig. 14 shows a flowchart of the temperature rise ripple process executed by the control device 80. The process shown in Fig. 14 is repeatedly executed by the processor 81, for example, at a predetermined control period.

[0062] After the process of step S13 is completed, the process proceeds to step S20. In step S20, each of the switch control units 92, 96 determines whether a switching condition for switching the phase currently being switched by each of the inverters 20, 30 is satisfied.

[0063] For example, if it is determined in step S20 that the period of time that has elapsed since it was determined that the switching condition was previously satisfied has reached the determination period, it may be determined that the switching condition is satisfied.

[0064] Also, for example, the temperature of the switch of the phase currently undergoing switching control is detected by the inverter temperature sensor 73, and if it is determined that the detected switch temperature exceeds the threshold temperature, it is determined that the switching condition is met.

[0065] If it is determined in step S20 that the switching condition is not satisfied, the process proceeds to step S14. On the other hand, if it is determined in step S20 that the switching condition is satisfied, the process proceeds to step S21. In step S21, each switch control unit 92, 96 selects, as an energized phase, one of the three phases other than the phase currently being switched, as the energized phase. For example, as shown in FIG. 15(a), the switching may be performed sequentially one phase at a time, such as U phase → V phase → W phase. Alternatively, as shown in FIG. 15(b), the switching may be performed sequentially two phases at a time, such as U, V phase → U, W phase → V, W phase.

[0066] After the process of step S21 is completed, in steps S14 and S15, switching control is performed on only the energized phase selected in step S21 among the three phases.

[0067] According to the present embodiment described above, it is possible to prevent the occurrence of an overheating abnormality in the switch of a specific phase in each of the inverters 20 and 30 .

[0068] Third Embodiment A third embodiment will now be described with reference to the drawings, focusing on differences from the second embodiment. In this embodiment, during temperature rise ripple processing, the occurrence of a situation in which heat generation continues in a switch of a specific arm out of the upper and lower arms of the first inverter 20 is suppressed.

[0069] Fig. 16 is a flowchart of the temperature rise ripple process executed by the control device 80. The process shown in Fig. 16 is repeatedly executed by the processor 81, for example, at a predetermined control cycle.

[0070] After completing the process of step S11, the process proceeds to step S30, where the first switch control unit 92 determines whether a switching condition is met. This condition is a condition for switching the switch that increases the ratio of the on period in one switching cycle Tsw in the first inverter 20 from one of the first upper and lower arm switches to the other.

[0071] For example, if it is determined in step S30 that the period of time that has elapsed since it was determined that the switching condition was previously satisfied has reached the determination period, it may be determined that the switching condition is satisfied.

[0072] Also, for example, the temperatures of the upper and lower arm switches are detected by the inverter temperature sensor 73, and if it is determined that the higher of the detected temperatures of the upper and lower arm switches exceeds the threshold temperature, it is determined that the switching condition is met.

[0073] If it is determined in step S30 that the switching condition is not met, the process proceeds to step S12. On the other hand, if it is determined in step S30 that the switching condition is met, the process proceeds to step S31. In step S31, the first switch control unit 92 subtracts the duty ratio Dtr calculated in step S11 from 1 to obtain a new duty ratio Dtr. Then, in step S14, the switching control of the first inverter 20 is performed based on the new duty ratio Dtr.

[0074] For example, if the duty ratio Dtr of the first inverter 20 is 0.75 before the switching condition is met as shown in Fig. 17, the new duty ratio Dtr is set to 0.25 (=1-0.75) after the switching condition is met as shown in Fig. 18. This makes it possible to prevent the first upper arm switches SUHa, SVHa, SWHa of each phase from continuing to generate heat.

[0075] Fourth Embodiment A fourth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, the amount of heat generated per unit time is changed by switching between a high heat generation mode and a low heat generation mode in the temperature rise ripple process.

[0076] The high heat generation mode will be described with reference to Fig. 19. In the high heat generation mode, the first switch control unit 92 and the second switch control unit 96 use the carrier signal SgC described in the first embodiment to generate drive signals in the same manner as described in the first embodiment.

[0077] The low-heat-generation mode will be described using FIG. 20 . In the low-heat-generation mode, the first switch control unit 92 and the second switch control unit 96 shift the phases of the carrier signals SgU, SgV, and SgW used to generate the drive signals for each of the three phases by 120 electrical degrees, as shown in FIG. 20 . SgU is a carrier signal for generating a U-phase drive signal in each of the inverters 20 and 30, SgV is a carrier signal for generating a V-phase drive signal in each of the inverters 20 and 30, and SgW is a carrier signal for generating a W-phase drive signal in each of the inverters 20 and 30. Each of the carrier signals SgU, SgV, and SgW has a maximum value Smax of 1, a minimum value of 0, and a median value of ½. Furthermore, the carrier signals SgU, SgV, and SgW each have the same period Tc, which is the same as the period Tc of the carrier signal SgC in FIG. 19 . The period Tc is the same as the switching period Tsw of the switch.

[0078] The carrier signal in the low heat generation mode can increase the ripple frequency of the phase current flowing through the armature winding, thereby reducing iron loss in the stator 50 of the rotating electrical machine 40. As a result, the amount of heat generated per unit time by the armature winding is reduced, and the temperature rise of the armature winding is suppressed.

[0079] Fig. 21 shows a flowchart of the temperature rise ripple process executed by the control device 80. The process shown in Fig. 21 is repeatedly executed by the processor 81, for example, at a predetermined control cycle.

[0080] After completing the process of step S13, the process proceeds to step S40, where it is determined whether the temperature increase request is large. For example, if it is determined that the temperature Tmr of the armature winding detected by the motor temperature sensor 74 is equal to or lower than the overheat threshold, it is determined that the temperature increase request is large, and if it is determined that the temperature Tmr of the armature winding exceeds the overheat threshold, it is determined that the temperature increase request is small.

[0081] If it is determined in step S40 that the temperature increase request is large, the process proceeds to step S41, where the large heat generation mode described in Fig. 19 is selected. On the other hand, if it is determined in step S40 that the temperature increase request is small, the process proceeds to step S42, where the small heat generation mode described in Fig. 20 is selected. After the process of step S41 or S42 is completed, the process proceeds to step S14.

[0082] By selecting the low heat generation mode, it is possible to continue the temperature rise ripple process while suppressing the temperature rise of the armature winding.

[0083] <Modification of Fourth Embodiment> The control device 80 may perform two-phase switching control instead of three-phase switching control in the first and second inverters 20, 30. In this case, the first switch control unit 92 and the second switch control unit 96 of the control device 80 may shift the phases of the carrier signals SgU, SgV used to generate drive signals for each of the two phases by 180 electrical degrees in the low heat generation mode, as shown in Fig. 22. Note that Fig. 22 shows an example in which the two phases to be switched are the U and V phases.

[0084] Fifth Embodiment A fifth embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, temperature rise ripple processing is performed when the rotor 41 is rotationally driven to run the vehicle.

[0085] FIG. 23 is a block diagram of the temperature rise ripple process.

[0086] The three-phase command value calculation unit 100 calculates U-, V-, and W-phase normalized command values ​​Dtu, Dtv, and Dtw. Specifically, the three-phase command value calculation unit 100 calculates a d-axis current command value Id* and a q-axis current command value Iq* in a dq coordinate system based on a command torque Trq* received from a control device that is higher in level than the control device 80.

[0087] The three-phase command value calculation unit 100 calculates the d-axis current value Idr and the q-axis current value Iqr based on the phase currents Iur, Ivr, and Iwr detected by the current sensor 70 and the electrical angle θr detected by the rotation angle sensor 71.

[0088] The three-phase command value calculation unit 100 calculates a d-axis voltage command value Vd* and a q-axis voltage command value Vq* based on the d- and q-axis current command values ​​Id* and Iq* and the d- and q-axis current values ​​Idr and Iqr. The three-phase command value calculation unit 100 calculates U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* based on the d- and q-axis voltage command values ​​Vd* and Vq* and the electrical angle θr. The U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* are command values ​​for voltages applied to the U-, V-, and W-phase windings 51U, 51V, and 51W, and are shifted in phase by 120 electrical degrees.

[0089] The three-phase command value calculation unit 100 calculates U-, V-, and W-phase normalized command values ​​Dtu, Dtv, and Dtw by normalizing the U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* by the inter-terminal voltage V1r of the first battery 11 detected by the voltage sensor 72. Specifically, the U-, V-, and W-phase normalized command values ​​Dtu, Dtv, and Dtw are values ​​obtained by dividing the U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* by 1 / 2 of V1r.

[0090] The superimposing unit 103 calculates U-, V-, and W-phase final command values ​​D*tu, D*tv, and D*tw by adding a voltage correction value CF, which will be described later, to the U-, V-, and W-phase normalized command values ​​Dtu, Dtv, and Dtw.

[0091] The first switch control unit 92 generates drive signals for the switches SUHa to SWLa of the first inverter 20 based on a magnitude comparison between the calculated U-, V-, and W-phase final command values ​​D*tu, D*tv, and D*tw (corresponding to "modulated waves") and the carrier signal SgC. The first switch control unit 92 also generates drive signals for the switches SUHb to SWLb of the second inverter 30 based on a magnitude comparison between the calculated U-, V-, and W-phase final command values ​​D*tu, D*tv, and D*tw and a carrier signal that is 180 degrees out of phase with the carrier signal SgC.

[0092] On the other hand, the center correction unit 101 calculates the corrected ratio Dc by subtracting 0.5 from the duty ratio Dtr calculated by the duty command unit 91 and multiplying the result by 2. The center correction unit 101 is provided to adjust the relationship of the voltage correction value CF to the carrier signal SgC in the magnitude comparison with the carrier signal SgC in the first switch control unit 92.

[0093] The normalization unit 102 calculates a voltage correction value CF by normalizing the calculated corrected ratio Dc with the inter-terminal voltage V1r of the first battery 11. More specifically, the normalization unit 102 calculates the voltage correction value CF by multiplying the corrected ratio Dc by "V1r / 2." The voltage correction value CF is a parameter for suppressing the occurrence of an overheating state in the armature winding.

[0094] In this embodiment, the duty command unit 91, the center correction unit 101, the normalization unit 102, the superimposition unit 103, and the first switch control unit 92 correspond to a "first processing unit."

[0095] The current deviation calculation unit 94 calculates the current deviation ΔI (= IM* - Izr) between the target ripple current IM* (corresponding to the "target value") calculated by the ripple current command unit 90 and the calculated zero-phase current Izr.

[0096] The selection unit 104 selects the drive signal generated by either the first switch control unit 92 or the second switch control unit 96 as the drive signal to be input to the second inverter 30. The selection unit 104 is, for example, a multiplexer. If the selection unit 104 determines that there is no temperature increase request, it selects the drive signal for each switch SUHb to SWLb of the second inverter 30, generated by the first switch control unit 92. On the other hand, if the selection unit 104 determines that there is a temperature increase request, it selects the drive signal for each switch SUHb to SWLb of the second inverter 30, generated by the second switch control unit 96.

[0097] In this embodiment, the ripple current command unit 90, the current deviation calculation unit 94, the current feedback control unit 95, the second switch control unit 96, and the selection unit 104 correspond to a "second processing unit."

[0098] Incidentally, when the vehicle is stopped and the torque generated by the rotary electric machine 40 is set to zero, the U-, V-, and W-phase normalized command values ​​Dtu, Dtv, and Dtw calculated by the three-phase command value calculation unit 100 may be set to zero.

[0099] 24 shows the calculation results of the transitions of the currents Im1, Im2, the zero-phase current Izr, and the phase currents Iur, Ivr, and Iwr flowing through the first and second batteries 11, 12. As described above, in this embodiment, the temperature rise ripple process can be performed even when the rotating electric machine 40 is driven to run the vehicle.

[0100] Other Embodiments The above-described embodiments may be modified as follows.

[0101] In the fifth embodiment, the processes of the second to fourth embodiments may be applied.

[0102] The circuit configuration of the control system is not limited to the configuration shown in FIG. 1, and may be, for example, the configurations shown in FIGS.

[0103] (A) The main changes from FIG. 1 in the configuration shown in FIG. 25 will be described. In FIG. 25, the emitters of the first lower arm switches SULa, SVLa, and SWLa for each phase are not connected to the emitters of the second lower arm switches SULb, SVLb, and SWLb for each phase, and are in an electrically isolated state (corresponding to the "second state"). On the other hand, the collectors of the first upper arm switches SUHa, SVHa, and SWHa for each phase are connected to the collectors of the second upper arm switches SUHb, SVHb, and SWHb for each phase via a changeover switch 61 provided in the control system 10. The changeover switch 61 is a switch similar to the changeover switch 60 in FIG. 1. The control device 80 performs temperature rise ripple processing with the changeover switch 61 turned on.

[0104] Here, the main changes from the first embodiment will be described.

[0105] 2 calculates the duty ratio Dtr as the ratio of the on-period Ton of the first lower arm switches SULa, SVLa, SWLa of each phase to one switching period Tsw, rather than the on-period Ton of the first upper arm switches SUHa, SVHa, SWHa of each phase. The first switch control unit 92 may keep the first upper arm switches SUHa, SVHa, SWHa of each phase off during the temperature rise ripple process. The second switch control unit 96 may keep the second lower arm switches SULa, SVLa, SWLa of each phase off during the temperature rise ripple process.

[0106] (B) In the configuration shown in Fig. 26, the main changes from Fig. 25 will be described. In Fig. 26, 60 will be referred to as a first changeover switch, and 61 will be referred to as a second changeover switch.

[0107] The control device 80 performs the temperature rise ripple process with the first changeover switch 60 turned on and the second changeover switch 61 turned off. In this case, the control device 80 performs the temperature rise ripple process described in the first embodiment.

[0108] The control device 80 performs the temperature rise ripple process with the first changeover switch 60 turned off and the second changeover switch 61 turned on. In this case, the control device 80 performs the temperature rise ripple process described above in (A).

[0109] (C) In the configuration shown in Fig. 27, the main changes from Fig. 25 will be described. The emitters of the first lower arm switches SULa, SVLa, SWLa of the first inverter 20 for each phase and the emitters of the second lower arm switches SULb, SVLb, SWLb of the second inverter 30 for each phase are connected.

[0110] The control system includes a first switch 62, a second switch 63, a connection path 64, and a connection switch 65 as components for connecting the first battery 11 and the second battery 12 in series or in parallel.

[0111] The negative terminal of the first battery 11 and the positive terminal of the second battery 12 are connected by a connection path 64. A connection switch 65 is provided on the connection path 64.

[0112] A first switch 62 connects the portion of the connection path 64 closer to the first battery 11 than the connection switch 65 to the emitters of the first lower arm switches SULa, SVLa, and SWLa of each phase. A second switch 63 connects the portion of the connection path 64 closer to the second battery 12 than the connection switch 65 to the collectors of the second lower arm switches SULb, SVLb, and SWLb of each phase.

[0113] When performing temperature rise ripple processing with the first battery 11 and the second battery 12 in series connection mode, the control device 80 turns off the changeover switch 60, the first switch 62, and the second switch 63, and turns on the connection switch 65.

[0114] On the other hand, when the control device 80 performs temperature rise ripple processing by setting the first battery 11 and the second battery 12 in parallel connection mode, it turns on the first switch 62 and the second switch 63 and turns off the changeover switch 60 and the connection switch 65.

[0115] (D) The configuration shown in FIG. 28 will be described.

[0116] The control system includes two sets of the first and second inverters 20, 30 shown in Fig. 1 and a six-phase rotating electric machine 140. The rotating electric machine 140 includes a rotor 141 including field poles 142 (e.g., permanent magnets). In this configuration, the temperature rise ripple processing described in each of the above embodiments can be performed in each of the two sets of the first and second inverters 20, 30.

[0117] The method of calculating the target ripple current IM* is not limited to that shown in Fig. 3. For example, the positive target ripple current IM* and the negative target ripple current IM* may each be an AC signal that is a trapezoidal wave or a rectangular wave, as long as the positive target ripple current IM* and the negative target ripple current IM* satisfy a point-symmetric relationship with respect to the zero-cross timing of the target ripple current IM* in one cycle Th.

[0118] Furthermore, the method for calculating the target ripple current I M* is not limited to the point-symmetrical method. For example, the target ripple current I M* may be calculated so that the period from the first zero-crossing timing C1 to the second zero-crossing timing C2 of the target ripple current I M* is different from the period from the second zero-crossing timing C2 to the third zero-crossing timing C3 of the target ripple current I M* in one cycle Th, and the area S1 of the first region is equal to the area S2 of the second region. Even in this case, the balance of the charge and discharge currents of the first battery 11 and the second battery 12 in one cycle Th can be balanced.

[0119] Furthermore, as a method for calculating the target ripple current IM*, the target ripple current IM* may be calculated so that the area S1 of the first region and the area S2 of the second region are different from each other.

[0120] The carrier signal is not limited to a triangular wave signal, but may be, for example, a sawtooth wave signal.

[0121] The rotating electric machine is not limited to a permanent magnet field type synchronous machine, and may be, for example, an induction machine.

[0122] The semiconductor switches constituting the first inverter and the second inverter are not limited to IGBTs, but may be, for example, Si-MOSFETs or GaN-MOSFETs, which are wide bandgap semiconductor switches. In this case, for example, the high-potential terminal of the switch is the drain, the low-potential terminal is the source, and the switch has a body diode.

[0123] The inverter, rotating electric machine, and control device may be installed in a mobile body other than a vehicle, such as an aircraft or a ship. If the mobile body is an aircraft, the rotating electric machine serves as a power source for the aircraft's flight, and if the mobile body is a ship, the rotating electric machine serves as a power source for the ship's navigation. Furthermore, the inverter, rotating electric machine, and control device may be installed in a mobile body other than a vehicle.

[0124] The control unit and method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0125] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. An inverter control device (80) applied to a system (10) including: a rotating electric machine (40, 140) having a multi-phase armature winding (51U to 51W); a first inverter (20) having first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) connected in series for the number of phases, the series-connected body of the first upper and lower arm switches being connected in parallel to a first power storage unit (11); and a second inverter (30) having second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) connected in series for the number of phases, the series-connected body of the second upper and lower arm switches being connected in parallel to a second power storage unit (12), In each phase, the low potential side terminal of the first upper arm switch and the high potential side terminal of the first lower arm switch are electrically connected to first ends (51Ua to 51Wa) of the armature windings, and in each phase, the low potential side terminal of the second upper arm switch and the high potential side terminal of the second lower arm switch are electrically connected to second ends (51Ub to 51Wb) of the armature windings, a first processing unit (91, 92, 101-103) that performs a first process to control at least one of the first upper and lower arm switches when the first state is either a first state in which the high potential terminal of the first upper arm switch and the high potential terminal of the second upper arm switch are electrically disconnected in each phase and the low potential terminal of the first lower arm switch and the low potential terminal of the second lower arm switch are electrically connected in each phase, or a second state in which the low potential terminal of the first lower arm switch and the low potential terminal of the second lower arm switch are electrically disconnected in each phase and the high potential terminal of the first upper arm switch and the high potential terminal of the second upper arm switch are electrically connected in each phase; and a second processing unit (90, 93-96, 104) that performs a second process to control at least one of the second upper and lower arm switches while the first process is being performed, The first processing unit performs, as the first processing, a process of controlling at least one of the first upper and lower arm switches to control amplitude of AC current flowing through the armature winding, and the second processing unit performs, as the second processing, a process of controlling at least one of the second upper and lower arm switches to control amplitude of AC current flowing through the second power storage unit.An inverter control device that controls at least one of the lower arm switches.

2. The inverter control device according to claim 1, wherein, when the first state is set, the first processing unit performs, as the first processing, a process of controlling a duty ratio which is a ratio of an on-period of the first upper arm switch to one switching period in order to control the amplitude of the AC current flowing through the armature winding, and the second processing unit performs, as the second processing, a process of controlling the second lower arm switch in order to feedback-control the AC current flowing through the second power storage unit to a target value (Ib*, IM*), and a process of increasing the amplitude of the target value as the duty ratio decreases.

3. The inverter control device according to claim 1, wherein, when the second state is set, the first processing unit performs, as the first processing, a process of controlling a duty ratio which is a ratio of an on-period of the first lower arm switch to one switching period in order to control the amplitude of the AC current flowing through the armature winding, and the second processing unit performs, as the second processing, a process of controlling the second upper arm switch in order to feedback-control the AC current flowing through the second power storage unit to a target value (Ib*, IM*), and a process of increasing the amplitude of the target value as the duty ratio decreases.

4. The inverter control device according to claim 2 or 3, wherein the first processing unit reduces the duty ratio when the temperature of the rotating electric machine is high compared to when the temperature of the rotating electric machine is low.

5. An inverter control device according to any one of claims 1 to 3, wherein the first processing unit and the second processing unit sequentially switch the phases to be switched among the phases of the first and second inverters while the first processing and the second processing are being executed.

6. An inverter control device as claimed in any one of claims 1 to 3, wherein the first processing unit performs the first process by alternately turning on the first upper arm switch and the first lower arm switch, and while the first process is being performed, alternately switches between the first upper arm switch and the first lower arm switch whichever switch has a higher ratio of on period in one switching cycle.

7. An inverter control device according to any one of claims 1 to 3, wherein the first processing unit performs, as the first processing, processing to control at least one of the first upper and lower arm switches in each of the three phases by PWM processing based on a magnitude comparison between a carrier signal and a three-phase modulated wave; the second processing unit performs, as the second processing, processing to control at least one of the second upper and lower arm switches in each of the three phases by PWM processing based on a magnitude comparison between a carrier signal and a three-phase modulated wave; the first processing unit shifts the phase of the carrier signal to be compared with the three-phase modulated wave in the first processing by 120 degrees in electrical angle; and the second processing unit shifts the phase of the carrier signal to be compared with the three-phase modulated wave in the second processing by 120 degrees in electrical angle.

8. An inverter control device according to any one of claims 1 to 3, wherein the first processing unit performs, as the first processing, processing to control at least one of the first upper and lower arm switches in each of the two phases by PWM processing based on a comparison of the magnitude between a carrier signal and the modulated waves of two phases; the second processing unit performs, as the second processing, processing to control at least one of the second upper and lower arm switches in each of the two phases by PWM processing based on a comparison of the magnitude between a carrier signal and the modulated waves of two phases; the first processing unit shifts the phase of the carrier signal to be compared with the modulated waves of two phases in the first processing by 180 degrees in electrical angle; and the second processing unit shifts the phase of the carrier signal to be compared with the modulated waves of two phases in the second processing by 180 degrees in electrical angle.

9. A program applied to a system (10) including: a rotating electric machine (40, 140) having a multi-phase armature winding (51U to 51W); a first inverter (20) having first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) connected in series for the same number of phases, the series-connected body of the first upper and lower arm switches being connected in parallel to a first power storage unit (11); and a second inverter (30) having second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) connected in series for the same number of phases, the series-connected body of the second upper and lower arm switches being connected in parallel to a second power storage unit (12), In each phase, a low potential side terminal of the first upper arm switch and a high potential side terminal of the first lower arm switch are electrically connected to first ends (51Ua to 51Wa) of the armature windings, and in each phase, a low potential side terminal of the second upper arm switch and a high potential side terminal of the second lower arm switch are electrically connected to second ends (51Ub to 51Wb) of the armature windings, and a processor (81) a first process for controlling at least one of the first upper and lower arm switches when the state is either a first state in which the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically disconnected in each phase and the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically connected in each phase, or a second state in which the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically disconnected in each phase and the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically connected in each phase; and a second process for controlling at least one of the second upper and lower arm switches while the first process is being executed, the first process being a process for controlling at least one of the first upper and lower arm switches so as to control the amplitude of the AC current flowing through the armature winding, The second process is a program for controlling at least one of the second upper and lower arm switches to control the amplitude of the AC current flowing through the second power storage unit.

10. An inverter control method applied to a system (10) including: a rotating electric machine (40, 140) having a multi-phase armature winding (51U to 51W); a first inverter (20) having first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) connected in series for the same number of phases, the series-connected body of the first upper and lower arm switches being connected in parallel to a first power storage unit (11); and a second inverter (30) having second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) connected in series for the same number of phases, the series-connected body of the second upper and lower arm switches being connected in parallel to a second power storage unit (12), In each phase, the low potential side terminal of the first upper arm switch and the high potential side terminal of the first lower arm switch are electrically connected to first ends (51Ua to 51Wa) of the armature windings, and in each phase, the low potential side terminal of the second upper arm switch and the high potential side terminal of the second lower arm switch are electrically connected to second ends (51Ub to 51Wb) of the armature windings, a first processing step of performing a first processing to control at least one of the first upper and lower arm switches when the state is either a first state in which the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically disconnected in each phase and the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically connected in each phase, or a second state in which the low potential side terminal of the first lower arm switch and the low potential side terminal of the second lower arm switch are electrically disconnected in each phase and the high potential side terminal of the first upper arm switch and the high potential side terminal of the second upper arm switch are electrically connected in each phase; and a second processing step of performing a second processing to control at least one of the second upper and lower arm switches while the first processing is being performed, wherein in the first processing step, the first processing is performed to control at least one of the first upper and lower arm switches so as to control the amplitude of the AC current flowing through the armature winding, In the second processing step, as the second processing, the second upper,An inverter control method that performs processing to control at least one of the lower arm switches.

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