Control apparatus, control program, and control method

Abstract

A control apparatus (60) is applied to a system (100) comprising: a rotary electric machine (40) having multiple-phase armature windings (51U, 51V, 51W); a first inverter (20); a second inverter (30); a positive electrode-side bus bar (11); a negative electrode-side bus bar (12); and a capacitor (15) connected between the positive electrode-side bus bar and the negative electrode-side bus bar. The control apparatus (60) is provided with a discharge control unit (72) that, when the capacitor is determined to be discharged, causes electric charges of the capacitor to flow to all of the multiple-phase armature windings and discharges the electric charges in a first discharge pattern in which first upper arm switches and second lower arm switches of all phases are turned on, or in a second discharge pattern in which first lower arm switches and second upper arm switches of all phases are turned on.

Description

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

[0001] This application is based on Japanese Application No. 2023-221324, filed on December 27, 2023, the contents of which are incorporated herein by reference.

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

[0003] Conventionally, various techniques have been devised for discharging the charge in the capacitor connected to the inverter when the power switch between the inverter and the battery is turned off, such as the technique disclosed in Patent Document 1.

[0004] Patent No. 3289567

[0005] In recent years, systems have been proposed in which a first inverter is connected to one end of the armature winding of a rotating electrical machine, and a second inverter is connected to the other end. Even in such systems, there has been a demand for a technology that can quickly discharge the charge in the capacitor.

[0006] A primary object of the present disclosure is to provide a control device, a control program, and a control method that are capable of rapid discharge.

[0007] A first means for solving the above problem includes 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source, a second inverter having second upper arm switches and second lower arm switches connected in series for the same number of phases, a positive side bus bar for electrically connecting, in each phase, a high potential side terminal of the first upper arm switch and a high potential side terminal of the second upper arm switch, and a positive side bus bar for connecting, in each phase, a high potential side terminal of the first lower arm switch. a negative-side busbar electrically connecting a low-potential side terminal of the first upper-arm switch and a low-potential side terminal of the second lower-arm switch, and a capacitor connected between the positive-side busbar and the negative-side busbar, and a control device applied to a system including a control unit that, when it is decided to discharge the capacitor, discharges the charge of the capacitor by flowing it to the armature windings of all phases in a first discharge pattern that turns on the first upper-arm switches and the second lower-arm switches of all phases, or in a second discharge pattern that turns on the first lower-arm switches and the second upper-arm switches of all phases.

[0008] A second means for solving the above problem includes 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source, a second inverter having second upper arm switches and second lower arm switches connected in series for the same number of phases, a positive side bus bar for electrically connecting, in each phase, a high potential side terminal of the first upper arm switch and a low potential side terminal of the second upper arm switch, and a low potential side terminal of the first lower arm switch for each phase. a negative-side busbar electrically connecting the positive-side terminal of the first upper arm switch and the low-potential side terminal of the second lower arm switch, and a capacitor connected between the positive-side busbar and the negative-side busbar, when it is determined to discharge the capacitor, a control program executed by a control device executes a discharge control process to discharge the charge of the capacitor by flowing it to the armature windings of all phases in a first discharge pattern that turns on the first upper arm switches and the second lower arm switches of all phases, or a second discharge pattern that turns on the first lower arm switches and the second upper arm switches of all phases.

[0009] A third means for solving the above problem includes 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source, a second inverter having second upper arm switches and second lower arm switches connected in series for the same number of phases, a positive side bus bar for electrically connecting, in each phase, a high potential side terminal of the first upper arm switch and a high potential side terminal of the second upper arm switch, and a positive side bus bar for electrically connecting, in each phase, a high potential side terminal of the first lower arm switch. A control method implemented by a control device applied to a system including a negative side busbar that electrically connects a low potential side terminal and the low potential side terminal of the second lower arm switch, and a capacitor connected between the positive side busbar and the negative side busbar, includes, when it is decided to discharge the capacitor, a discharge control process that flows the charge of the capacitor to the armature windings of all phases to discharge it in a first discharge pattern that turns on the first upper arm switches and the second lower arm switches of all phases, or in a second discharge pattern that turns on the first lower arm switches and the second upper arm switches of all phases.

[0010] According to the above means, current can be passed through the armature windings of all phases, and the current can be quickly discharged.

[0011] 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 a diagram showing the configuration of a control system, Fig. 2 is a block diagram showing functions related to switching control, Fig. 3 is a block diagram showing functions related to discharge control, Fig. 4 is a circuit diagram showing current flow in a first discharge pattern, Fig. 5 is a circuit diagram showing current flow in a second discharge pattern, Fig. 6 is a flowchart of a discharge process, Fig. 7 is a block diagram showing functions related to discharge control in a second embodiment, Fig. 8 is an explanatory diagram of current vectors, Fig. 9 is a flowchart of a discharge process in the second embodiment, Fig. 10 is a circuit diagram showing a discharge path in the second embodiment, Fig. 11 is a circuit diagram showing a discharge path in the second embodiment, Fig. 12 is a circuit diagram showing a discharge path in the second embodiment, and Fig. 13 is a diagram showing the configuration of a control system in a third embodiment.

[0012] The control device, control program, and control method of the present disclosure will be described in multiple embodiments and their modifications with reference to the drawings. In each embodiment and modification, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals. For corresponding and / or associated parts, the description of the embodiments can be referenced.

[0013] First Embodiment A control device 60 according to this embodiment is mounted on an electric vehicle such as an electric car or a hybrid car, and is applied to a control system 100 for a rotating electrical machine 40 (hereinafter simply referred to as the control system 100).

[0014] As shown in FIG. 1 , the control system 100 of this embodiment includes a battery 10 , a first inverter 20 , a second inverter 30 , a rotating electrical machine 40 , and a control device 60 .

[0015] The battery 10 is, for example, a battery pack including a series connection of unit cells, and is a DC power supply in this embodiment. 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.

[0016] The first inverter 20 and the second inverter 30 are power conversion circuits that convert DC power supplied from the battery 10 into three-phase AC power and supply it to the rotating electric machine 40 .

[0017] The first inverter 20 includes a series connection of a U-phase first upper arm switch SUHa and a U-phase first lower arm switch SULa, a V-phase first upper arm switch SVHa and a V-phase first lower arm switch SVLa, and a W-phase first upper arm switch SWHa and a W-phase first lower arm switch SWLa. Hereinafter, these will be collectively referred to as switches SUHa to SWLa.

[0018] Similarly, the second inverter 30 includes a series connection of a U-phase second upper arm switch SUHb and a U-phase second lower arm switch SULb, a series connection of a V-phase second upper arm switch SVHb and a V-phase second lower arm switch SVLb, and a series connection of a W-phase second upper arm switch SWHb and a W-phase second lower arm switch SWLb. Hereinafter, these will be collectively referred to as switches SUHb to SWLb.

[0019] In this embodiment, voltage-controlled semiconductor switching elements, more specifically, IGBTs, are used as the switches SUHa to SWLa and SUHb to SWLb. In this embodiment, the high-potential terminal of each switch is the collector, and the low-potential terminal is the emitter. Freewheeling diodes DUHa, DVHa, DWHa, DULa, DVLa, DWLa, DUHb, DVHb, DWHb, DULb, DVLb, and DWLb are connected in anti-parallel to the switches SUHa, SVHa, SWHa, SULa, SVLa, SWLa, SUHb, SVHb, SWHb, SULb, SVLb, and SWLb, respectively.

[0020] 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 electrically connected by a positive bus 11 serving as a high-potential side connecting line such as a bus bar. The emitters of the first lower arm switches SULa, SVLa, SWLa of each phase and the emitters of the second lower arm switches SULb, SVLb, SWLb of each phase are electrically connected by a negative bus 12 serving as a low-potential side connecting line such as a bus bar.

[0021] The positive terminal of the battery 10 is electrically connected to the positive bus 11, and the negative terminal of the battery 10 is electrically connected to the negative bus 12. The battery 10 is electrically connected to the buses 11, 12 on the opposite side of the first inverter 20 from the second inverter 30.

[0022] The rotating electric machine 40 is, for example, a main motor mounted on a vehicle. A rotor 41 of the rotating electric machine 40 is capable of transmitting power to drive wheels (not shown) 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 42 (for example, neodymium magnets) as field poles.

[0023] The rotating electric machine 40 includes a stator 50. The stator 50 includes armature windings, namely, a U-phase winding 51U, a V-phase winding 51V, and a W-phase winding 51W. The phase windings 51U, 51V, and 51W are arranged with an electrical angle of 120°. The phase windings 51U, 51V, and 51W are open-connected, and both ends of each phase winding 51U, 51V, and 51W are electrically connected to the first inverter 20 or the second inverter 30.

[0024] Specifically, in each phase, first ends 51Ua, 51Va, 51Wa of the windings 51U, 51V, 51W are electrically connected to first upper switches SUHa, SVHa, SWHa and first lower switches SULa, SVLa, SWLa of the corresponding phase. Also, second ends 51Ub, 51Vb, 51Wb of the windings 51U, 51V, 51W are electrically connected to second upper switches SUHb, SVHb, SWHb and second lower switches SULb, SVLb, SWLb of the corresponding phase.

[0025] The control system 100 includes a positive-side selector switch 13a. The positive-side selector switch 13a is provided on the positive-side bus 11 between the first inverter 20 and the second inverter 30. When the positive-side selector switch 13a is turned on, it electrically connects the first inverter 20 and the second inverter 30 via the positive-side bus 11, and when the positive-side selector switch 13a is turned off, it electrically disconnects the first inverter 20 and the second inverter 30. The positive-side selector switch 13a is controlled by the control device 60. The positive-side selector switch 13a is provided to switch the driving state of the control system 100, as will be described later.

[0026] The positive-side selector switch 13a is a semiconductor switch, specifically an N-channel IGBT. The collector of the positive-side selector switch 13a is connected to the first inverter 20 (i.e., the positive terminal of the battery 10) and the emitter is connected to the second inverter 30. A freewheel diode DH is connected in antiparallel to the positive-side selector switch 13a. That is, the anode of the freewheel diode DH is connected to the emitter of the positive-side selector switch 13a and the cathode is connected to the collector of the positive-side selector switch 13a.

[0027] The control system 100 includes a negative-side selector switch 13b. The negative-side selector switch 13b is provided on the negative-side bus 12 between the first inverter 20 and the second inverter 30. When the negative-side selector switch 13b is turned on, it electrically connects the first inverter 20 and the second inverter 30 via the negative-side bus 12, and when turned off, it electrically disconnects the first inverter 20 and the second inverter 30. The negative-side selector switch 13b is controlled by the control device 60. The negative-side selector switch 13b is provided to switch the driving state of the control system 100, as will be described later.

[0028] The negative-side selector switch 13b is a semiconductor switch, specifically an N-channel IGBT. The collector of the negative-side selector switch 13b is connected to the second inverter 30, and the emitter is connected to the first inverter 20 (i.e., the negative terminal of the battery 10). A freewheel diode DL is connected in antiparallel to the negative-side selector switch 13b. That is, the anode of the freewheel diode DH is connected to the emitter of the negative-side selector switch 13b, and the cathode is connected to the collector of the negative-side selector switch 13b. The positive-side selector switch 13a and the negative-side selector switch 13b may be collectively referred to as the selector switch 13.

[0029] The control system 100 includes a power switch 14 as a power switch unit and a capacitor 15 as a smoothing capacitor. The power switch 14 is, for example, a semiconductor switching element or a relay. The power switch 14 is provided on the positive bus 11 between the positive terminal of the battery 10 and the first inverter 20. When the power switch 14 is turned on, it electrically connects the battery 10 and the rotating electric machine 40, and when it is turned off, it electrically disconnects the battery 10 and the rotating electric machine 40. The power switch 14 is driven by the control device 60.

[0030] A first end of the capacitor 15 is electrically connected to the positive bus 11 between the power switch 14 and the first inverter 20. A second end of the capacitor 15 is electrically connected to the negative bus 12 between the negative terminal of the battery 10 and the first inverter 20.

[0031] The control system 100 includes a current sensor 16 and a rotation angle sensor 17. The current sensor 16 detects phase currents Iu, Iv, and Iw flowing through the respective phase windings 51U, 51V, and 51W. In this embodiment, the current sensor 16 is provided at one of the ends of each phase winding 51U, 51V, and 51W closer to the first inverter 20. The sign of the detected value of the current sensor 16 is positive when the current flows from the first terminal 51Ua, 51Va, and 51Wa of each phase winding 51U, 51V, and 51W to the second terminal 51Ub, 51Vb, and 51Wb, and negative when the current flows from the second terminal 51Ub, 51Vb, and 51Wb to the first terminal 51Ua, 51Va, and 51Wa. Note that the current sensor 16 may also be provided at one of the ends of each phase winding 51U, 51V, and 51W closer to the second inverter 30.

[0032] The rotation angle sensor 17 is, for example, a resolver, and detects the electrical angle θ of the rotor 41. The phase currents Iur, Ivr, and Iwr detected by the current sensor 16 and the electrical angle θr detected by the rotation angle sensor 17 are input to the control device 60.

[0033] The control system 100 includes a voltage sensor 18 that detects a system voltage Vsys between the positive bus 11 and the negative bus 12. The voltage sensor 18 is connected in parallel with the capacitor 15. That is, a first end of the voltage sensor 18 is electrically connected to the positive bus 11 between the power switch 14 and the first inverter 20. A second end of the voltage sensor 18 is electrically connected to the negative bus 12 between the negative terminal of the battery 10 and the first inverter 20. The detection result of the voltage sensor 18 is input to the control device 60. When the power switch 14 is turned on, the system voltage Vsys matches the power supply voltage of the battery 10, and when the power switch 14 is turned off, the system voltage Vsys matches the voltage across the capacitor 15.

[0034] The control device 60 is primarily composed of a microcomputer including a processing unit 60a such as a CPU and a storage unit 60b such as various types of memory. The functions provided by the microcomputer can be provided by software stored in a physical memory device and a computer executing the software, software alone, hardware alone, or a combination thereof. For example, when the microcomputer is provided by electronic circuits, which are hardware, the functions can be provided by digital circuits including numerous logic circuits or analog circuits. For example, the processing unit 60a of the microcomputer executes programs stored in a non-transitory tangible storage medium (non-transitory tangible storage medium) that serves as the storage unit 60b. The programs include, for example, control programs that realize the functions shown in Figures 2 and 3. Execution of a program (e.g., a control program) results in the execution of a method (e.g., a control method) corresponding to the program. The storage unit 60b is, for example, a non-volatile memory. The programs stored in the storage unit 60b can be downloaded and updated via a communication network such as the Internet, for example, via OTA (Over the Air).

[0035] The control device 60 has a function of switching the drive state of the control system 100 between a Y drive state and an H drive state by controlling the selector switch 13. The control device 60 sets the control system 100 to the Y drive state (first mode) by turning off the selector switch 13, turning on the second upper arm switches SUHb, SVHb, and SWHb of each phase, and turning off the lower arm switches SULb, SVLb, and SWLb of each phase. In the Y drive state, the phase windings 51U, 51V, and 51W are Y-connected via the second inverter 30. On the other hand, the control device 60 sets the control system 100 to the H drive state (second mode) by turning on the selector switch 13.

[0036] In the Y drive state, the control device 60 controls the switching of the switches SUHa to SWLa in the first inverter 20. In addition, in the H drive state, the control device 60 controls the switching of both the switches SUHa to SWLa in the first inverter 20 and the switches SUHb to SWLb in the second inverter 30. By appropriately switching between the Y drive state and the H drive state and executing switching control, the control system 100 can be made to have a high output and high efficiency.

[0037] The control device 60 has various functions for executing switching control. The switching control in this embodiment will be described assuming current feedback control, but torque feedback control may also be performed. Furthermore, although PWM control will be described below, overmodulation control or square wave control may also be performed.

[0038] The functions for executing the switching control will be described with reference to Fig. 2. Fig. 2 is a functional block diagram for explaining various functions for realizing the switching control. Note that the various functions of the control device 60 are realized, for example, by the arithmetic processing unit 60a executing a program stored in the storage unit 60b.

[0039] As shown in FIG. 2, the control device 60 includes a current command generating unit 61, a dq conversion unit 62, a current control unit 63, a UVW conversion unit 64, a duty ratio calculation unit 65, and a switch control unit 66 as functions for performing current control.

[0040] The current command generating unit 61 receives a torque command value Trq* from a higher-level control device than the control device 60. Based on the received torque command value Trq*, the current command generating unit 61 calculates a d-axis current command value Id* and a q-axis current command value Iq* in a dq coordinate system using a torque-dq map or the like. Hereinafter, the d-axis current command value Id* and the q-axis current command value Iq* may be collectively referred to as d- and q-axis current command values ​​Id* and Iq*.

[0041] The dq converter 62 receives the phase currents Iur, Ivr, and Iwr detected by the current sensor 16 and the electrical angle θr detected by the rotation angle sensor 17. The dq converter 62 calculates a d-axis current value Idr and a q-axis current value Iqr based on the detected phase currents Iur, Ivr, and Iwr and the electrical angle θr. The d-axis current value Idr and the q-axis current value Iqr may be collectively referred to as the d- and q-axis current values ​​Idr and Iqr.

[0042] The current control unit 63 receives the difference between the d-axis and q-axis current command values ​​Id* and Iq* and the d-axis and q-axis current values ​​Idr and Iqr. More specifically, the current control unit 63 receives the d-axis current deviation, which is the difference between the d-axis current command value Id* and the d-axis current value Idr, and calculates a d-axis voltage command value Vd* as a manipulated variable for feedback-controlling the input d-axis current deviation to zero. The current control unit 63 also receives the q-axis current deviation, which is the difference between the q-axis current command value Iq* and the q-axis current value Iqr, and calculates a q-axis voltage command value Vq* as a manipulated variable for feedback-controlling the input q-axis current deviation to zero. The feedback control is, for example, proportional-plus-integral control.

[0043] The d- and q-axis voltage command values ​​Vd* and Vq* and the detected electrical angle θr are input to the UVW converter 64. Based on the input d- and q-axis voltage command values ​​Vd* and Vq* and the electrical angle θr, the UVW converter 64 calculates a U-phase voltage command value Vu*, a V-phase voltage command value Vv*, and a W-phase voltage command value Vw*. Hereinafter, these may be collectively referred to as the respective phase voltage command values ​​Vu*, Vv*, and Vw*.

[0044] The phase voltage command values ​​Vu*, Vv*, and Vw* are command values ​​for the phase voltages Vu, Vv, and Vw. In this embodiment, the signs of the phase voltages Vu, Vv, and Vw are positive when the potentials of the first terminals 51Ua, 51Va, and 51Wa of the windings 51U, 51V, and 51W are higher than the potentials of the second terminals 51Ub, 51Vb, and 51Wb of the windings 51U, 51V, and 51W, respectively, and negative when the potentials of the second terminals 51Ub, 51Vb, and 51Wb of the windings 51U, 51V, and 51W are higher than the potentials of the first terminals 51Ua, 51Va, and 51Wa of the windings 51U, 51V, and 51W.

[0045] The duty ratio calculation unit 65 calculates the duty ratios DTu, DTv, DTw (duty ratios) of the respective phases based on the respective phase voltage command values ​​Vu*, Vv*, Vw* and the system voltage Vsys.

[0046] The switch control unit 66 receives the duty ratios DTu, DTv, and DTw of the respective phases, and generates operation signals for the switches SUHa to SWLa of the first inverter 20 and operation signals for the switches SUHb to SWLb of the second inverter 30 based on the duty ratios DTu, DTv, and DTw of the respective phases and a carrier signal. The carrier signal is, for example, a triangular wave signal. Switching control of the first inverter 20 and the second inverter 30 is performed based on the generated operation signals.

[0047] When performing maintenance, inspection, repair, etc. on the inverters 20, 30 or the rotating electrical machine 40, the power switch 14 is turned off. At this time, if charge accumulates in the capacitor 15, it becomes difficult to perform the work, so it is necessary to discharge the capacitor 15. Therefore, in this embodiment, the following functions are provided. The functions related to discharging the capacitor 15 in this embodiment will be described below.

[0048] 3, the control device 60 has a function as a discharge determination unit 71 that determines whether or not to perform discharge, and a function as a discharge control unit 72 that performs control related to discharge. These functions are realized, for example, by the arithmetic processing device 60a executing a program (control program) stored in the storage unit 60b.

[0049] The discharge determination unit 71 monitors the on / off state of the power switch 14, and when the power switch 14 is turned off, determines to discharge the capacitor 15. The discharge determination unit 71 may determine to discharge the capacitor 15 based on an instruction from an external higher-level control device, or may determine to discharge the capacitor 15 when a vehicle abnormality or collision is detected. In either case, the discharge is premised on the power switch 14 being in the off state. When the discharge determination unit 71 determines to discharge the capacitor 15, it notifies the discharge control unit 72 to that effect.

[0050] When the discharge control unit 72 is notified by the discharge determination unit 71 that it has been decided to discharge the capacitor 15 , the discharge control unit 72 controls the switches SUHa to SWLa and SUHb to SWLb of the inverters 20 and 30 so as to discharge the capacitor 15 .

[0051] More specifically, the discharge control unit 72 turns on the selector switch 13 to switch to the H drive state. The discharge control unit 72 then turns on the first upper arm switches SUHa, SVHa, and SWHa and the second lower arm switches SULb, SVLb, and SWLb of all phases so that current flows through the windings 51U, 51V, and 51W of all phases (see FIG. 4). Alternatively, the discharge control unit 72 turns on the first lower arm switches SULa, SVLa, and SWLa and the second upper arm switches SUHb, SVHb, and SWHb of all phases so that current flows through the windings 51U, 51V, and 51W of all phases (see FIG. 5). At this time, the discharge control unit 72 controls the switches SUHa to SWLa and SUHb to SWLb so that the maximum current flows through the windings 51U, 51V, and 51W of each phase. Further, currents of the same magnitude and in the same direction are simultaneously passed through the windings 51U, 51V, and 51W of all phases.

[0052] As shown in Fig. 4, a state in which the first upper arm switches SUHa, SVHa, SWHa and the second lower arm switches SULb, SVLb, SWLb of all phases are turned on is defined as a first discharge pattern. As shown in Fig. 5, a state in which the first lower arm switches SULa, SVLa, SWLa and the second upper arm switches SUHb, SVHb, SWHb of all phases are turned on is defined as a second discharge pattern.

[0053] The discharge control unit 72 may discharge the capacitor 15 using either the first discharge pattern or the second discharge pattern, or may switch between the first discharge pattern and the second discharge pattern at predetermined time intervals to discharge the capacitor 15.

[0054] As shown in FIG. 2, the discharge control unit 72 may instruct the switch control unit 66 to turn on and off each of the switches SUHa to SWLa and SUHb to SWLb, causing the switch control unit 66 to control the on and off of each of the switches SUHa to SWLa and SUHb to SWLb.

[0055] Next, the discharge process for performing discharge will be described with reference to Fig. 6. The discharge process is performed by the control device 60 at a predetermined timing. For example, it is performed at predetermined intervals.

[0056] The control device 60 determines whether or not the discharge determination unit 71 has determined to discharge (step S101). If the result of this determination is negative, the control device 60 terminates the discharge process. On the other hand, if the discharge has been determined (if the result of the determination in step S101 is positive), the control device 60 causes the discharge control unit 72 to control the switches SUHa-SWLa and SUHb-SWLb of the inverters 20 and 30 (step S102). That is, the capacitor 15 is discharged using the first discharge pattern or the second discharge. The details of the discharge control are as described above.

[0057] The effects of the above embodiment will be described.

[0058] When discharge is determined, the discharge control unit 72 turns on the selector switch 13 to switch to the H drive state and turns on the first upper arm switches SUHa, SVHa, and SWHa and the second lower arm switches SULb, SVLb, and SWLb of all phases (see FIG. 4). Alternatively, the discharge control unit 72 turns on the first lower arm switches SULa, SVLa, and SWLa and the second upper arm switches SUHb, SVHb, and SWHb of all phases. This causes current to flow through the windings 51U, 51V, and 51W of all phases. At this time, the discharge control unit 72 can control the switches SUHa to SWLa and SUHb to SWLb so that the maximum current flows. This allows discharge to be performed in a short period of time.

[0059] Furthermore, because currents of the same magnitude and in the same direction flow simultaneously through windings 51U, 51V, and 51W of all phases, it is possible to prevent torque from being generated in rotating electric machine 40 during discharge, thereby preventing unnecessary vibrations and noise from being generated when rotating electric machine 40 operates during discharge.

[0060] (Modification of the First Embodiment) In the first embodiment, current may be continuously applied to the windings 51U, 51V, and 51W of all phases until discharge is complete. However, discharge may be intermittently applied. For example, the discharge control unit 72 may set a predetermined duty ratio (duty ratios DTu, DTv, and DTw of each phase) and input (instruct) it to the switch control unit 66, as shown in FIG. 2. Based on the input duty ratio, the switch control unit 66 may turn on and off the switches SUHa to SWLa and SUHb to SWLb in the first discharge pattern or the second discharge pattern so that current flows through all phases. This makes it possible to adjust the duty ratio so as to prevent excessive heat generation and excessive current flow.

[0061] In the first embodiment, the discharge control unit 72 may perform current feedback control so that a predetermined amount of current flows. For example, as shown in FIG. 2 , the discharge control unit 72 instructs (outputs) the current command generation unit 61 to specify (output) a predetermined amount of current. The current command generation unit 61 generates and outputs a d-axis current command value Id* so that the predetermined amount of current flows. The q-axis current command value Iq* is set to zero so that no torque is generated. The current control unit 63 receives the difference between the d- and q-axis current command values ​​Id* and Iq* and the d- and q-axis current values ​​Idr and Iqr, performs feedback control, and calculates the d- and q-axis voltage command values ​​Vd* and Vq*. The subsequent processing is the same as described above and will not be described here. This allows the switches SUHa to SWLa and SUHb to SWLb to be turned on and off using the first or second discharge pattern so that a predetermined amount of current flows.

[0062] In this way, the amount of current during discharge can be determined, so that excessive heat generation and excessive current flow can be prevented. Furthermore, because the amount of current is constant, it is possible to complete discharge within a predetermined time.

[0063] Second Embodiment A second embodiment will be described in which the configuration of the control device 60 of the first embodiment is partially modified.

[0064] For safety reasons, the discharge control must be performed even when the control system 100 malfunctions, the vehicle malfunctions, or a collision occurs. However, when the control system 100 malfunctions, the vehicle malfunctions, or a collision occurs, the rotation angle sensor 17 may malfunction, one of the electrical paths may be disconnected, or one of the switches SUHa to SWLa, SUHb to SWLb may malfunction. In other words, there may be cases where current cannot flow through all phases using the first discharge pattern or the second discharge pattern. Therefore, in the second embodiment, the on / off patterns of the switches SUHa to SWLa, SUHb to SWLb are changed depending on the abnormality state. This is explained below.

[0065] 7, the control device 60 has a function as an abnormality detection unit 73 that detects abnormalities in various components. For example, the abnormality detection unit 73 can detect an abnormality in the rotation angle sensor 17 based on the detection result of the rotation angle sensor 17. An abnormality in the rotation angle sensor is a failure of the rotation angle sensor 17, a break in the electrical path from the rotation angle sensor 17 to the control device 60, etc., and the detection method is a well-known method.

[0066] Furthermore, the abnormality detection unit 73 is configured to detect whether an abnormality has occurred in any of the electrical paths of the U, V, and W phases based on the detection results from the current sensor 16. Abnormalities in the electrical paths include breaks in the electrical paths of each phase in each of the inverters 20 and 30 and breaks in the phase windings 51U, 51V, and 51W. Specifically, based on the detected phase currents Iur, Ivr, and Iwr, the abnormality detection unit 73 detects an abnormality in the electrical path if no current is detected in an electrical path through which current should flow based on the switching patterns of the switches SUHa-SWLa and SUHb-SWLb. Since the phase currents Iur, Ivr, and Iwr of each phase can be detected, it is possible to identify which electrical path has an abnormality.

[0067] Furthermore, the abnormality detection unit 73 can detect an OFF failure (disconnection failure, failure that prevents the switch from being turned on) of any of the switches SUHa to SWLa and SUHb to SWLb from the switching pattern and the detection result from the current sensor 16. Note that a failure of the switches SUHa to SWLa and SUHb to SWLb may be detected as an abnormality in the electrical path.

[0068] In addition, the abnormality detection unit 73 may acquire error information from an external device regarding abnormalities in the rotation angle sensor 17, abnormalities in the electrical paths, and abnormalities in each of the switches SUHa to SWLa and SUHb to SWLb, and detect the above abnormalities based on the error information.

[0069] When the abnormality detection unit 73 detects an abnormality, it outputs (notifies) to the discharge control unit 72 that the abnormality has been detected and error information relating to the location of the abnormality.

[0070] When the discharge control unit 72 is notified by the discharge determination unit 71 that it has decided to discharge the capacitor 15 and receives error information from the abnormality detection unit 73, the discharge control unit 72 changes a part of the switching pattern.

[0071] To explain in more detail, if an abnormality is detected only in the rotation angle sensor 17, that is, if no abnormality in the electrical path or in the switches SUHa to SWLa and SUHb to SWLb is detected, the discharge control unit 72 discharges the capacitor 15 using the first discharge pattern or the second discharge pattern, as in the first embodiment.

[0072] On the other hand, if an abnormality is detected in only one of the three-phase electrical paths, the discharge control unit 72 turns on the changeover switch 13 to switch to the H drive state and controls the switches SUHa-SWLa and SUHb-SWLb to pass current through the remaining two-phase windings 51U, 51V, and 51W. Examples of an abnormality in only one of the electrical paths include a break in only one of the phase windings 51U, 51V, and 51W, or a break in the electrical path from the U-phase first upper arm switch SUHa to the U-phase winding 51U.

[0073] Furthermore, when performing the above control, the discharge control unit 72 instructs the electric current to flow in the d-axis direction by two-phase drive based on the electrical angle θr detected by the rotation angle sensor 17 .

[0074] More specifically, in the H drive state, as shown in Figure 8, it is possible to pass a negative current in each phase (U-phase, V-phase, W-phase) (indicated by the dashed lines). As a result, even if an abnormality occurs in the electrical path of one of the phases, by controlling the currents of the remaining two phases in the H drive state, it is possible to pass a current in the d-axis direction without passing a current in the q-axis direction, regardless of the d-axis direction. In other words, unlike the Y drive state, it is possible to set the q-axis current to zero and discharge without generating torque in the rotating electric machine 40.

[0075] Furthermore, when any one of the switches SUHa to SWLa, SUHb to SWLb has an OFF fault, the discharge control unit 72 turns on the changeover switch 13 to switch to the H drive state, as described above, and controls the remaining switches SUHa to SWLa, SUHb to SWLb so that the switch with the OFF fault passes current to the two-phase windings 51U, 51V, 51W that are not in use and are normal.

[0076] Furthermore, in cases other than those described above (such as when an abnormality is detected in the rotation angle sensor 17 or any of the electrical paths), if there is an electrical path through which current can flow normally, the discharge control unit 72 flows current through that electrical path to discharge the current. Note that an electrical path through which current can flow normally is an electrical path through which current can be normally supplied and cut off.

[0077] At this time, the discharge control unit 72 controls the on / off of each switch SUHa to SWLa and SUHb to SWLb so that the current direction is reversed at predetermined intervals. More specifically, the current direction is reversed at a speed that is not synchronized with the rotational speed of the rotor 41, that is, so that the rotor 41 does not rotate. This allows the rotor 41 to remain in place even if torque is generated.

[0078] Next, the discharge process in the second embodiment will be described with reference to FIG. 9 . The control device 60 determines whether the discharge determination unit 71 has determined to discharge (step S201). If the determination result is negative, the control device 60 terminates the discharge process. On the other hand, if the discharge determination unit 71 has determined to discharge (if the determination result in step S201 is positive), the control device 60 determines whether the abnormality detection unit 73 has detected an abnormality (step S202). If the determination result is negative, the control device 60 causes the discharge control unit 72 to control the switches SUHa-SWLa and SUHb-SWLb of the inverters 20 and 30 (step S203), similar to step S102 in the first embodiment. That is, the capacitor 15 is discharged using the first discharge pattern or the second discharge pattern.

[0079] If the determination result in step S202 is positive (if an abnormality is detected), the control device 60 determines whether an abnormality has occurred only in the rotation angle sensor 17 based on the error information (step S204). If the determination result is positive, the control device 60 proceeds to the process of step S203. That is, the control device 60 discharges the capacitor 15 using the first discharge pattern or the second discharge pattern.

[0080] On the other hand, if the determination result in step S204 is negative, the control device 60 determines whether an abnormality has occurred in only one phase of the electrical path (step S205). If the determination result is positive, the control device 60 switches to the H drive state and controls each of the switches SUHa to SWLa and SUHb to SWLb so that current flows in the d-axis direction in two-phase drive (step S206). Note that even if only an ON fault is detected in one of the switches SUHa to SWLa and SUHb to SWLb, the determination result in step S205 is also used to perform step S206.

[0081] On the other hand, if the determination result in step S205 is negative (in the case of an abnormal state other than those described above), the control device 60 determines whether or not there is an electrical path through which current can flow normally, based on the error information (step S207). If the determination result is positive, the control device 60 controls the switches SUHa to SWLa and SUHb to SWLb so that current flows through the normal electrical path (step S208). At this time, as described above, the control device 60 controls the switches SUHa to SWLa and SUHb to SWLb so that the current direction is reversed at predetermined intervals.

[0082] On the other hand, if the determination result in step S207 is negative, the control device 60 turns off all of the switches SUHa to SWLa and SUHb to SWLb, outputs an error notification without discharging (step S209), and ends the discharge process.

[0083] With the above configuration, for example, if an abnormality occurs only in the first upper arm switch SUHa, as shown in Figure 10, discharge can be achieved by passing a negative current (shown by the dashed line) through the U phase and the W phase, and a positive current (shown by the broken line) through the V phase.

[0084] Furthermore, for example, if an abnormality occurs in the electrical path of the U phase, discharge can be achieved by passing a positive current (indicated by the dashed line) through the V phase and a negative current (indicated by the dashed line) through the W phase, as shown in Fig. 11. Depending on the direction of the d-axis, a positive current may be passed through the V phase and the W phase, as shown in Fig. 12.

[0085] According to the second embodiment, the following effects are achieved.

[0086] When an abnormality is detected, the control device 60 changes the discharge control depending on the location of the abnormality. That is, it changes the switching pattern to change the electrical path for discharge. This allows discharge to be performed using an appropriate discharge method depending on the location of the abnormality.

[0087] If an abnormality occurs in only one of the electrical paths, the control device 60 switches to the H drive state and controls the switches SUHa to SWLa and SUHb to SWLb to pass current in the d-axis direction in two-phase drive. This allows the rotating electrical machine 40 to discharge without generating torque.

[0088] Furthermore, if abnormalities occur in multiple locations but there is an electrical path through which current can flow normally, the control device 60 discharges current by passing it through the normal electrical path. At this time, the control device 60 controls each of the switches SUHa to SWLa and SUHb to SWLb so as to reverse the current direction at predetermined intervals. This allows the rotor 41 to remain in place even if torque is generated.

[0089] Third Embodiment A third embodiment will be described in which the configuration of the control device 60 of the first embodiment is partially modified.

[0090] 13 , in the third embodiment, a capacitor 115 is connected to the side of the second inverter 30. Hereinafter, the capacitor 15 will be referred to as a first capacitor 15, and the capacitor 115 will be referred to as a second capacitor 115.

[0091] A first end of the second capacitor 115 is connected to the positive bus 11 at a position outside the second inverter 30. That is, the second inverter 30 is arranged between the first end of the second capacitor 115 and the positive selector switch 13 a. A second end of the second capacitor 115 is connected to the negative bus 12 at a position outside the second inverter 30. That is, the second inverter 30 is arranged between the second end of the second capacitor 115 and the negative selector switch 13 b.

[0092] Furthermore, a voltage sensor 118 is connected in parallel with the second capacitor 115. Hereinafter, the voltage sensor 118 will be referred to as the first voltage sensor 18, and the voltage sensor 118 will be referred to as the second voltage sensor 118. The second voltage sensor 118 is configured to detect the voltage across the terminals of the second capacitor 115. The detection result is input to the control device 60.

[0093] As shown in Figure 13, when the second capacitor 115 is provided, the charges of the first capacitor 15 and the second capacitor 115 cannot be sufficiently discharged using only either the first discharge pattern or the second discharge pattern. Furthermore, the discharge cannot be completed quickly (it takes a long time). More specifically, if the voltage of one of the capacitors 15, 115 is high, a portion of the current flows back to the other capacitor 15, 115 via the freewheeling diodes DUHa, DVHa, DWHa, DUHb, DVHb, and DWHb. In other words, the other capacitor 15, 115 is charged, and the discharge cannot be completed quickly.

[0094] Therefore, the discharge control unit 72 of the third embodiment is configured to alternately switch between the first discharge pattern and the second discharge pattern at a predetermined timing. For example, the discharge control unit 72 is configured to alternately switch between the first discharge pattern and the second discharge pattern every time a predetermined time period elapses.

[0095] According to the third embodiment, the following effects are achieved.

[0096] When the second capacitor 115 is provided, the discharge control unit 72 alternately switches between the first discharge pattern and the second discharge pattern at a predetermined timing, thereby enabling both the first capacitor 115 and the second capacitor 115 to be discharged appropriately and in a short time.

[0097] (Variation of the Third Embodiment) In the third embodiment, the discharge control unit 72 may switch between the first discharge pattern and the second discharge pattern based on a comparison between the detected voltage of the first voltage sensor 18 and the detected voltage of the second voltage sensor 118. Specifically, if the detected voltage of the first voltage sensor 18 is greater than the detected voltage of the second voltage sensor 118, the discharge control unit 72 switches to the first discharge pattern, and if the detected voltage of the first voltage sensor 18 is less than the detected voltage of the second voltage sensor 118, the discharge control unit 72 switches to the second discharge pattern.

[0098] In this way, by switching between the first discharge pattern and the second discharge pattern based on a comparison between the detected voltage of the first voltage sensor 18 and the detected voltage of the second voltage sensor 118, it is possible to switch at an appropriate timing depending on the charge (storage state) of each capacitor 15, 115, and discharge in a short period of time.

[0099] In the third embodiment, the discharge control unit 72 may switch between the first discharge pattern and the second discharge pattern when the discharge amount exceeds a predetermined amount. The discharge amount can be calculated from the phase currents Iur, Ivr, and Iwr detected by the current sensor 16 and the discharge time. The predetermined amount may be determined based on the capacitance of the first capacitor 15 and the capacitance of the second capacitor 115.

[0100] In this way, when the discharge amount exceeds a predetermined amount, the first discharge pattern and the second discharge pattern are switched, allowing the switching to be done at an appropriate timing depending on the charge (storage state) of each capacitor 15, 115, and discharging to be performed in a short time.

[0101] (Variant examples of the above embodiments) In the above embodiments, the discharge control unit 72 was notified by the discharge decision unit 71 provided in the control device 60 that it had been decided to discharge the capacitor 15, but the notification that discharge had been decided may also be received from outside the control device 60.

[0102] In each of the above embodiments, it is not necessary to configure the drive state to be switchable to the Y drive state. In this case, the changeover switch 13 is not necessary.

[0103] The controller and methods described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the controller and methods described herein may be implemented by a special-purpose computer configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the controller and methods described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0104] The following describes characteristic configurations extracted from the above-described embodiments.

[0105] [Configuration 1] A rotating electric machine (40) having a multi-phase armature winding (51U, 51V, 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source (10); 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; a positive side bus (11) electrically connecting a high potential side terminal of the first upper arm switch and a high potential side terminal of the second upper arm switch in each phase; and a negative side bus (12) electrically connecting a low potential side terminal of the first lower arm switch and a low potential side terminal of the second lower arm switch in each phase. a capacitor (15) connected between the positive busbar and the negative busbar, the control device (60) being applied to a system (100) including: a capacitor (15) connected between the positive busbar and the negative busbar, the control device including a discharge control unit (72) that, when it is decided to discharge the capacitor, discharges the charge of the capacitor by flowing it to the armature windings of all phases in a first discharge pattern that turns on the first upper arm switches and the second lower arm switches of all phases, or in a second discharge pattern that turns on the first lower arm switches and the second upper arm switches of all phases.

[0106] [Configuration 2] The control device according to Configuration 1, wherein the rotating electric machine has at least three-phase armature windings, and includes a rotation angle sensor (17) that detects a rotation angle of the rotating electric machine, and the discharge control unit, when an abnormality occurs in an electrical path of any one of the phases of the electrical paths, discharges the electric current by passing it through the normal two-phase armature windings so that the current flows in the d-axis direction based on the rotation angle detected by the rotation angle sensor.

[0107] [Configuration 3] The control device according to Configuration 1 or 2, wherein the rotating electric machine is a synchronous motor, and the discharge control unit switches between the first discharge pattern and the second discharge pattern at a speed that is not synchronized with the rotation speed of the rotating electric machine, thereby discharging while reversing the direction of the current flowing through the armature winding.

[0108] [Configuration 4] The control device according to any one of configurations 1 to 3, wherein the capacitors include a first capacitor (15) connected to the first inverter side and a second capacitor (115) connected to the second inverter side, and the discharge control unit switches between the first discharge pattern and the second discharge pattern to discharge the current while reversing the direction of the current flowing through the armature winding.

[0109] [Configuration 5] The control device according to Configuration 4, wherein a first voltage sensor (18) that detects a terminal-to-terminal voltage of the first capacitor and a second voltage sensor (118) that detects a terminal-to-terminal voltage of the second capacitor are connected between the positive bus bar and the negative bus bar, and the discharge control unit switches between the first discharge pattern and the second discharge pattern based on a comparison result between the terminal-to-terminal voltage of the first capacitor acquired from the first voltage sensor and the terminal-to-terminal voltage of the second capacitor acquired from the second voltage sensor.

[0110] [Configuration 6] The control device according to Configuration 4, wherein the discharge control unit calculates a discharge current amount based on a current detection value of each phase acquired from a current detection unit that detects a phase current flowing through the armature winding of each phase and a discharge time, and switches between the first discharge pattern and the second discharge pattern when the discharge current amount reaches a predetermined value.

[0111] [Configuration 7] The control device according to any one of Configurations 1 to 6, wherein the discharge control unit performs feedback control of the discharge current so that a current detection value of each phase acquired from a current detection unit that detects a phase current flowing through the armature winding of each phase becomes a predetermined current value.

[0112] [Configuration 8] The control device according to any one of configurations 1 to 6, wherein the discharge control unit switches on and off each of the switches so as to achieve a predetermined duty ratio.

[0113] [Configuration 9] A rotating electric machine (40) having a multi-phase armature winding (51U, 51V, 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source (10); 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; a positive side bus (11) electrically connecting a high potential side terminal of the first upper arm switch and a high potential side terminal of the second upper arm switch in each phase; and a negative side bus (12) electrically connecting a low potential side terminal of the first lower arm switch and a low potential side terminal of the second lower arm switch in each phase. a capacitor (15) connected between the positive busbar and the negative busbar, when it is determined to discharge the capacitor, the control program executes a discharge control process in which the charge of the capacitor is discharged by flowing it to the armature windings of all phases in a first discharge pattern in which the first upper arm switches and the second lower arm switches of all phases are turned on, or in a second discharge pattern in which the first lower arm switches and the second upper arm switches of all phases are turned on.

[0114] [Configuration 10] A rotating electric machine (40) having a multi-phase armature winding (51U, 51V, 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, and a series connection of the first upper arm switches and the first lower arm switches connected in parallel to a DC power source (10); 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; a positive side bus (11) electrically connecting a high potential side terminal of the first upper arm switch and a high potential side terminal of the second upper arm switch in each phase; and a negative side bus (12) electrically connecting a low potential side terminal of the first lower arm switch and a low potential side terminal of the second lower arm switch in each phase. a capacitor (15) connected between the positive busbar and the negative busbar, when it is determined to discharge the capacitor, the control method includes a discharge control process of flowing and discharging the charge of the capacitor to the armature windings of all phases in a first discharge pattern that turns on the first upper arm switches and the second lower arm switches of all phases, or in a second discharge pattern that turns on the first lower arm switches and the second upper arm switches of all phases.

[0115] 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. A rotating electrical machine (40) having a multi-phase armature winding (51U, 51V, 51W), a first inverter (20) having a number of series-connected first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) corresponding to the number of phases, with the series connection of the first upper arm switches and the first lower arm switches being connected in parallel to a DC power supply (10), a second inverter (30) having a number of series-connected second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) corresponding to the number of phases, a positive bus bar (11) electrically connecting the high-potential side terminals of the first upper arm switches and the high-potential side terminals of the second upper arm switches in each phase, a negative bus bar (12) electrically connecting the low-potential side terminals of the first lower arm switches and the low-potential side terminals of the second lower arm switches in each phase, and a capacitor (15) connected between the positive bus bar and the negative bus bar. In a control device (60) applied to a system (100) including these components, when the discharge of the capacitor is determined, a first discharge pattern in which all the first upper arm switches and the second lower arm switches in all phases are turned on, or a second discharge pattern in which all the first lower arm switches and the second upper arm switches in all phases are turned on, and a discharge control unit (72) that discharges the charge of the capacitor by flowing it through the armature windings in all phases.

2. The rotating electrical machine has at least three-phase armature windings, includes a rotation angle sensor (17) for detecting the rotation angle of the rotating electrical machine, and the discharge control unit, when an abnormality occurs in any one of the electrical paths of each phase, discharges by flowing a current through the normal two-phase armature windings so as to flow a current in the d-axis direction based on the rotation angle detected by the rotation angle sensor. The control device according to claim 1.

3. The rotating electrical machine is a synchronous motor, and the discharge control unit discharges while switching between the first discharge pattern and the second discharge pattern at a speed that is not synchronized with the rotation speed of the rotating electrical machine, while reversing the direction of the current flowing through the armature windings. The control device according to claim 1.

4. The capacitor includes a first capacitor (15) connected to the first inverter side and a second capacitor (115) connected to the second inverter side. The discharge control unit discharges while switching between the first discharge pattern and the second discharge pattern to reverse the direction of the current flowing through the armature winding. The control device according to claim 1.

5. A first voltage sensor (18) for detecting the voltage across the terminals of the first capacitor and a second voltage sensor (118) for detecting the voltage across the terminals of the second capacitor are connected between the positive bus bar and the negative bus bar. The discharge control unit switches between the first discharge pattern and the second discharge pattern based on the comparison result between the voltage across the terminals of the first capacitor obtained from the first voltage sensor and the voltage across the terminals of the second capacitor obtained from the second voltage sensor. The control device according to claim 4.

6. The discharge control unit calculates the discharge current amount based on the current detection value of each phase obtained from a current detection unit that detects the phase current flowing through the armature winding of each phase and the discharge time. When the discharge current amount reaches a predetermined value, the discharge control unit switches between the first discharge pattern and the second discharge pattern. The control device according to claim 4.

7. The discharge control unit feedback-controls the discharge current so that the current detection value of each phase obtained from a current detection unit that detects the phase current flowing through the armature winding of each phase becomes a predetermined current value. The control device according to any one of claims 1 to 6.

8. The discharge control unit switches the on / off of each switch so as to obtain a predetermined duty ratio. The control device according to any one of claims 1 to 6.

9. A rotating electric machine (40) having a multi-phase armature winding (51U, 51V, 51W), a first inverter (20) having a number of series-connected first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) corresponding to the number of phases, with the series connection of the first upper arm switches and the first lower arm switches being connected in parallel to a DC power supply (10), a second inverter (30) having a number of series-connected second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) corresponding to the number of phases, a positive bus bar (11) that electrically connects the high-potential side terminals of the first upper arm switches and the high-potential side terminals of the second upper arm switches in each phase, a negative bus bar (12) that electrically connects the low-potential side terminals of the first lower arm switches and the low-potential side terminals of the second lower arm switches in each phase, and a capacitor (15) connected between the positive bus bar and the negative bus bar, in a control program implemented by a control device (60) applied to a system (100) including these components, when the discharge of the capacitor is determined, a first discharge pattern in which all-phase first upper arm switches and second lower arm switches are turned on, or a second discharge pattern in which all-phase first lower arm switches and second upper arm switches are turned on, and a discharge control process is performed to discharge the charge of the capacitor by flowing it through the armature windings of all phases.

10. A rotating electrical machine (40) having a multi-phase armature winding (51U, 51V, 51W), a first inverter (20) having a number of series-connected first upper-arm switches (SUHa to SWHa) and first lower-arm switches (SULa to SWLa) equal to the number of phases, with the series connection of the first upper-arm switches and the first lower-arm switches being connected in parallel to a DC power supply (10), a second inverter (30) having a number of series-connected second upper-arm switches (SUHb to SWHb) and second lower-arm switches (SULb to SWLb) equal to the number of phases, a positive busbar (11) electrically connecting the high-potential terminals of the first upper-arm switches and the high-potential terminals of the second upper-arm switches in each phase, a negative busbar (12) electrically connecting the low-potential terminals of the first lower-arm switches and the low-potential terminals of the second lower-arm switches in each phase, and a capacitor (15) connected between the positive busbar and the negative busbar. In a control method implemented by a control device (60) applied to a system (100) comprising these components, when discharge of the capacitor is determined, a first discharge pattern in which all the first upper-arm switches and the second lower-arm switches of all phases are turned on, or a second discharge pattern in which all the first lower-arm switches and the second upper-arm switches of all phases are turned on, and a discharge control process of flowing the charge of the capacitor through the armature windings of all phases to discharge it is included.

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