Control device for rotary electric machine, program, and control method for rotary electric machine

Abstract

A control device according to the present invention is used in a system (100) comprising a rotary electric machine (40), a first inverter (20), a second inverter (30), selector switches (QH, QL), a first capacitor (15a), a second capacitor (15b), and power switches (MH, ML). The control device comprises: a determination unit (90, 190, 290) that determines whether or not there is an indication that a power switch will be turned off; and a discharge control unit (80, 81, 85, 86, 91, 191, 291) that discharges the second capacitor by controlling the selector switches, first upper arm switches (SUHa, SVHa, SWHa), first lower arm switches (SULa, SVLa, SWLa), second upper arm switches (SUHb, SVHb, SWHb), and second lower arm switches (SULb, SVLb, SWLb) during the period from when it is determined that there is an indication that a power switch will be turned off to when the power switch is turned off.

Description

Rotating electric machine control device, program, and rotating electric machine control method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-221323, filed on December 27, 2023, the contents of which are incorporated herein by reference.

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

[0003] Conventionally, a system for controlling a rotating electric machine using two inverters has been known. In this system, a first inverter is electrically connected to first ends of a multi-phase winding of the rotating electric machine, and a second inverter is electrically connected to second ends of the winding. The first inverter and the second inverter share a common connection line. A DC power supply and a first capacitor are electrically connected in parallel to the first inverter. A second capacitor is electrically connected in parallel to the second inverter. An example of such a technology is disclosed in Patent Document 1.

[0004] Japanese Patent Application Laid-Open No. 2021-125922

[0005] In the above-described system, a power switch may be provided in a path electrically connecting the first inverter and the DC power supply. When the power switch is turned off, the current flow between the DC power supply and the rotating electric machine is terminated. The power switch is turned off in response to a user instruction.

[0006] However, when the power switch is turned off, the first capacitor and the second capacitor may be discharged, and in this case, there is a concern that the discharge period of the capacitors may be longer than when a capacitor is provided only in the first inverter of the first and second inverters.

[0007] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a control device, program, and control method for a rotating electric machine that can shorten the discharge period of a capacitor when current flow between a DC power source and a rotating electric machine is terminated.

[0008] The present disclosure relates to a rotating electric machine having windings for multiple phases; a first inverter having first upper arm switches and first lower arm switches connected in series for the number of phases, and the series connection of the first upper arm switches and the first lower arm switches being 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 number of phases; a positive bus bar for each phase electrically connecting a high potential side terminal of the first upper arm switch to a high potential side terminal of the second upper arm switch; a negative bus bar for each phase electrically connecting a low potential side terminal of the first lower arm switch to a low potential side terminal of the second lower arm switch; a changeover switch provided on at least one of the positive bus bar and the negative bus bar; a first capacitor connected in parallel to the series connection of the first upper arm switch and the first lower arm switch; and a second capacitor connected in parallel to the series connection of the second upper arm switch and the second lower arm switch. a power switch provided in a path electrically connecting the first inverter and the DC power supply, 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 winding, 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 a second end of the winding, the control device comprising: a determination unit that determines whether there is a sign that the power switch will be turned off in response to an instruction from a user of the system; and a discharge control unit that performs discharge control to discharge the second capacitor by controlling the changeover switch, the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch during the period from when it is determined that there is a sign that the power switch will be turned off until the power switch is turned off.

[0009] In the present disclosure, discharge control is performed to discharge the second capacitor during the period from when it is determined that there is a sign that the power switch will be turned off in response to a user instruction from the system until the power switch is actually turned off. Therefore, the second capacitor is pre-discharged before the power switch is actually turned off, thereby reducing the charge accumulated in the second capacitor. As a result, the discharge time of the first capacitor and the second capacitor when the power switch is turned off can be shortened.

[0010] 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 functional block diagram of processing executed by a control device, Fig. 3 is a diagram illustrating a control mode of H drive control, Fig. 4 is a diagram illustrating a control mode of Y drive control, Fig. 5 is a flowchart illustrating the procedure of processing executed by the control device, Fig. 6 is a flowchart illustrating the procedure of processing executed by the control device, Fig. 7 is a time chart illustrating an example of control for discharging a capacitor, Fig. 8 is a time chart illustrating a comparative example of control for discharging a capacitor, Fig. 9 is a functional block diagram of processing executed by a control device according to a second embodiment, Fig. 10 is a flowchart illustrating the procedure of processing executed by the control device, Fig. 11 is a time chart illustrating an example of control for discharging a capacitor, Fig. 12 is a functional block diagram of processing executed by a control device according to a third embodiment, and Fig. 13 is a flowchart illustrating the procedure of processing executed by the control device.

[0011] 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.

[0012] A first embodiment of a control device according to the present disclosure will now be described with reference to the drawings. The control device of the present embodiment is mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle, and is applied to an in-vehicle control system.

[0013] As shown in FIG. 1 , the control system 100 includes a battery 10 (corresponding to a "DC power supply"), a first inverter 20, a second inverter 30, and a rotating electrical machine 40. The battery 10 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.

[0014] 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 .

[0015] 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. 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.

[0016] 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.

[0017] 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 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 such as a bus bar.

[0018] 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. In this case, the battery 10 is electrically connected in parallel to the first inverter 20.

[0019] The rotating electric machine 40 is an in-vehicle main motor. A rotor 41 of the rotating electric machine 40 is capable of transmitting power to drive wheels 43 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 (e.g., neodymium magnets) as field poles.

[0020] 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.

[0021] 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.

[0022] The control system 100 includes a positive-side selector switch QH and a negative-side selector switch QL. The positive-side selector switch QH is provided on the positive-side bus 11 between the first inverter 20 and the second inverter 30. The negative-side selector switch QL is provided on the negative-side bus 12 between the first inverter 20 and the second inverter 30. When turned on, each of the selector switches QH and QL electrically connects the first inverter 20 and the second inverter 30, and when turned off, electrically disconnects the first inverter 20 and the second inverter 30. In this embodiment, the selector switches QH and QL are controlled by a control device 60 included in the control system 100. As will be described later, each of the selector switches QH and QL is provided to switch the driving state of the control system 100.

[0023] In this embodiment, voltage-controlled semiconductor switching elements, more specifically, IGBTs, are used as the selector switches QH and QL. Freewheel diodes DH and DL are connected in parallel to the selector switches QH and QL. The freewheel diode DH connected in parallel to the positive selector switch QH has an anode electrically connected to the second inverter 30 and a cathode electrically connected to the first inverter 20. The freewheel diode DL connected in parallel to the negative selector switch QL has an anode electrically connected to the first inverter 20 and a cathode electrically connected to the second inverter 30.

[0024] The control system 100 includes a first capacitor 15a and a second capacitor 15b. A first end of the first capacitor 15a is electrically connected to the positive bus 11 between the battery 10 and the first inverter 20. A second end of the first capacitor 15a is electrically connected to the negative bus 12 between the negative terminal of the battery 10 and the first inverter 20. In other words, the first capacitor 15a is connected in parallel to the series connection of the first upper arm switches SUHa, SVHa, SWHa of each phase and the first lower arm switches SULa, SVLa, SWLa of each phase.

[0025] A first end of the second capacitor 15b is electrically connected to the positive bus 11 on the side opposite the positive selector switch QH with respect to the second inverter 30. A second end of the second capacitor 15b is electrically connected to the negative bus 12 on the side opposite the negative selector switch QL with respect to the second inverter 30. In other words, the second capacitor 15b is connected in parallel to the series-connected body of the second upper arm switches SUHb, SVHb, SWHb of each phase and the second lower arm switches SULb, SVLb, SWLb of each phase.

[0026] The control system 100 includes a positive power switch MH and a negative power switch ML. The positive power switch MH is provided between the battery 10 and a connection point of the positive bus 11 with a first end of the first capacitor 15a. The negative power switch ML is provided between the battery 10 and a connection point of the negative bus 12 with a second end of the first capacitor 15a. For example, each of the power switches MH and ML is a relay or a semiconductor switching element. Each of the power switches MH and ML is controlled by a control device 60.

[0027] The control system 100 includes a precharge switch MP and a resistor 13. A series connection of the precharge switch MP and the resistor 13 is connected in parallel to the negative-side power switch ML. The precharge switch MP is a relay or a semiconductor switching element. The precharge switch MP is controlled by a control device 60.

[0028] When the pre-charge switch MP is turned on, the current flow is limited by the resistor 13. Therefore, when current begins to flow between the battery 10 and the rotating electrical machine 40, the pre-charge switch MP is turned on before the negative power supply switch ML, and the positive power supply switch MH is turned on, thereby suppressing inrush current from flowing between the battery 10 and the rotating electrical machine 40.

[0029] The control system 100 includes a first voltage sensor 61, a second voltage sensor 62, a current sensor 63, and a rotation angle sensor 64. The first voltage sensor 61 detects the voltage of the first capacitor 15a. The second voltage sensor 62 detects the voltage of the second capacitor 15b. The current sensor 63 detects the phase current flowing through each of the phase windings 51U, 51V, and 51W. In this embodiment, the current sensor 63 is provided on the first inverter 20 side of each of the phase windings 51U, 51V, and 51W. The current sensor 63 may also be provided on the second inverter 30 side of each of the phase windings 51U, 51V, and 51W. The rotation angle sensor 64 is, for example, a resolver and detects the electrical angle of the rotor 41. The detected values ​​of the sensors 61 to 64 are input to the control device 60.

[0030] The control system 100 includes a start switch 70, a vehicle speed sensor 71, an accelerator sensor 72, a brake stroke sensor 73, a shift position sensor 74, a navigation device 75, and a parking brake sensor 76. The start switch 70 is, for example, an ignition switch or a push-button start switch, and is operated by the vehicle user. A signal notifying that the start switch 70 has been turned on or off is input to the control device 60.

[0031] The vehicle speed sensor 71 detects the vehicle speed Vs, which is the moving speed of the vehicle. The accelerator sensor 72 detects the accelerator operation amount Ac by a user (e.g., a driver). The accelerator operation amount detected by the accelerator sensor 72 is, for example, the depression amount of an accelerator pedal serving as an accelerator operation member. The brake stroke sensor 73 detects the brake stroke Br, which is the depression amount of a brake pedal serving as a brake operation member by the user. The detection values ​​of each sensor 71 to 73 are input to the control device 60.

[0032] The shift position sensor 74 detects a shift position, which is the position of a shift lever of a transmission (not shown). For example, the shift lever of the transmission is operated by a user. For example, the shift positions include a parking range (P range) used when parking the vehicle, a reverse range (R range) that instructs the vehicle to move backward, a neutral range (N range) that cuts off power transmission between the rotor 41 and the drive wheels 43, and a drive range (D range) that instructs the vehicle to move forward. A signal SH that notifies the shift position is input to the control device 60.

[0033] Map data including road data, background data, etc. is stored in the storage unit of the navigation device 75. The navigation device 75 displays the current location of the vehicle, searches for and provides guidance on a route to the destination, etc., based on the map data, destination information preset by the user, and current vehicle location information detected by a GPS sensor. The control device 60 is configured to be able to communicate with the navigation device 75 and to be able to receive destination information and current vehicle location information.

[0034] The parking brake sensor 76 detects whether the parking brake, which applies a braking force to the wheels of the vehicle, is activated. A brake signal Ps, which indicates the activation status of the parking brake detected by the parking brake sensor 76, is input to the control device 60.

[0035] The control device 60 is an electronic control unit (ECU) that performs various controls of the control system 100, and includes a processor 60a and a storage unit 60b as hardware. In the control system 100, each on-board device can be controlled by an ECU corresponding to that device. However, for convenience, multiple ECUs are shown as one control device 60 in FIG. 1 .

[0036] The memory unit 60b 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 60. The memory provides the processor 60a with a working area for temporary use when the processor 60a 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 60a, 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 of Figures 5, 6, 10, 13, etc., which will be described later.

[0037] For example, program information stored in a non-transient physical recording medium is installed in the storage unit 60b. 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 60b.

[0038] In order to control the control variable of the rotary electric machine 40 to a command value, the control device 60 controls the on / off of the changeover switches QH, QL and the switches SUHa to SWLa, SUHb to SWLb of the first and second inverters 20, 30 while keeping the power switches MH, ML on. In this embodiment, the control variable is torque.

[0039] FIG. 2 is a block diagram showing the control process of the rotating electrical machine 40 executed by the control device 60. As shown in FIG.

[0040] The dq-axis command value calculation unit 80 calculates a d-axis current command value Id* and a q-axis current command value Iq* in the dq coordinate system based on the torque command value Trq* received from a higher-level control device than the control device 60.

[0041] The first conversion unit 81 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 63 and the electrical angle θr detected by the rotation angle sensor 64.

[0042] The current feedback unit 82 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. Specifically, the current feedback unit 82 calculates a 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 calculated d-axis current deviation to zero. The current feedback unit 82 calculates a 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 calculated q-axis current deviation to zero. The feedback control is, for example, proportional-plus-integral control.

[0043] The second converter 83 calculates U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* based on the d- and q-axis voltage command values ​​Vd*, 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. The U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* are shifted in phase by 120° in electrical angle.

[0044] The speed calculation unit 84 calculates the rotation speed Nr of the rotor 41 based on the electrical angle θr.

[0045] The selection unit 85 determines whether the drive state of the control system 100 should be Y drive control or H drive control. In the present embodiment, the selection unit 85 selects whether Y drive control or H drive control should be used based on the operating point of the rotating electric machine 40, which is determined by the calculated rotation speed Nr and torque command value Trq*, and on the control map information. The control map information is information that defines the Y drive control region and the H drive control region in association with the rotation speed Nr and the torque command value Trq*. The control map information is stored in the storage unit 60b.

[0046] The switch control unit 86 generates a carrier signal for generating drive signals for the switches SUHa to SWLa and SUHb to SWLb of the first and second inverters 20 and 30. For example, the carrier signal is a triangular wave signal. The drive signals are comprised of switch on and off commands.

[0047] The switch control unit 86 generates drive signals for the switches SUHa to SWLa and SUHb to SWLb of the first and second inverters 20 and 30 based on the U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw*, the first voltage V1r which is the voltage detected by the first voltage sensor 61, and the generated carrier signal.

[0048] Specifically, the switch control unit 86 calculates U-, V-, and W-phase normalized command values ​​Dutyu, Dutyv, and Dutyw by normalizing the U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* by the first voltage V1r. Specifically, the U-, V-, and W-phase normalized command values ​​Dutyu, Dutyv, and Dutyw are values ​​obtained by dividing the U-, V-, and W-phase voltage command values ​​Vu*, Vv*, and Vw* by half the first voltage V1r.

[0049] 3, the switch control unit 86 performs H drive control by turning on the changeover switches QH, QL to PWM-drive the switches SUHa to SWLa of the first inverter 20 and PWM-drive the switches SUHb to SWLb of the second inverter 30. The switch control unit 86 generates drive signals for the switches SUHa to SWLa and SUHb to SWLb of the first and second inverters 20, 30 based on a magnitude comparison between the U-, V-, and W-phase normalized command values ​​Dutyu, Dutyv, and Dutyw and the carrier signal.

[0050] On the other hand, when Y drive control is selected by the selector 85, the switch control unit 86 performs Y drive control by turning off the changeover switches QH and QL and PWM-driving the switches SUHa to SWLa of the first inverter 20, as shown in FIG. 4 . The switch control unit 86 also fixes the second upper-arm switches SUHb, SVHb, and SWHb of the second inverter 30 to on and fixes the second lower-arm switches SULb, SVLb, and SWLb of the second inverter 30 to off. This results in a star connection of the phase windings 51U, 51V, and 51W via the second inverter 30. The switch control unit 86 generates drive signals for the switches SUHa to SWLa of the first inverter 20 based on a magnitude comparison between the U-, V-, and W-phase normalized command values ​​Dutyu, Dutyv, and Dutyw and the carrier signal.

[0051] Based on the generated drive signal, the switch control unit 86 controls the charge / discharge current of the gates of the switches SUHa-SWLa and SUHb-SWLb of the first and second inverters 20 and 30. As a result, the on / off of the switches SUHa-SWLa and SUHb-SWLb of the first and second inverters 20 and 30 is controlled in accordance with the drive signal.

[0052] The switching patterns of the switches SUHa to SWLa and SUHb to SWLb, which are switched according to the drive signal in the H drive control, are shifted in phase by 120° in electrical angle in each phase. Also, the switching patterns of the switches SUHa to SWLa of the first inverter 20, which are switched according to the drive signal in the Y drive control, are shifted in phase by 120° in electrical angle in each phase.

[0053] 5 is a flowchart showing the control process of the rotary electric machine 40 executed by the control device 60. The process shown in FIG. 5 is repeatedly executed by the processor 60a of the control device 60, for example, at a predetermined control cycle.

[0054] In step S10, the selection unit 85 acquires the torque command value Trq* and the rotation speed Nr calculated by the speed calculation unit 84.

[0055] In step S11, the selection unit 85 selects either the Y drive control or the H drive control based on the torque command value Trq* and the rotation speed Nr.

[0056] If the Y drive state is selected in step S11, the process proceeds to step S13, where the switch control unit 86 executes the Y drive control shown in Fig. 4. On the other hand, if the H drive state is selected in step S11, the process proceeds to step S14, where the switch control unit 86 executes the H drive control shown in Fig. 3.

[0057] The control device 60 turns off the power switches MH and ML to terminate the flow of current between the battery 10 and the rotating electrical machine 40. For example, when a signal notifying that the start switch 70 has been turned off is input, the control device 60 turns off the power switches MH and ML.

[0058] The control device 60 discharges the capacitors 15a, 15b while the power switches MH, ML are turned off. In this case, there is a concern that the discharge period of the capacitors may be longer than when a capacitor is provided only in the first inverter 20 of the inverters 20, 30. In addition, due to regulatory requirements, it is desirable that the discharge period of the capacitors 15a, 15b after the power switches MH, ML are turned off be short.

[0059] Therefore, in this embodiment, the control device 60 has the following configuration in order to shorten the discharge time of the capacitor when the current supply between the battery 10 and the rotating electrical machine 40 is terminated.

[0060] Returning to the description of FIG. 2 , the control device 60 includes a determination unit 90 and a zero-axis command value calculation unit 91. The determination unit 90 determines whether there is a sign that the power switches MH and ML will be turned off in response to an instruction from the user of the control system 100. In this embodiment, the determination unit 90 receives as input the rotation speed Nr calculated by the speed calculation unit 84, the torque command value Trq* received from a higher-level control device, the vehicle speed Vs detected by the vehicle speed sensor 71, the accelerator operation amount Ac detected by the accelerator sensor 72, and the brake stroke Br detected by the brake stroke sensor 73. Based on the various input values, the determination unit 90 determines whether there is a sign that the power switches MH and ML will be turned off in response to an instruction from the user. The processing performed by the determination unit 90 will be described later.

[0061] The determination unit 90 outputs a notification signal Sg to the zero-axis command value calculation unit 91 to notify that there is a sign that the power switches MH and ML will be turned off in response to a user instruction. The notification signal Sg is a binary signal. A notification signal Sg of logic L notifies that it has been determined that there is no sign that the power switches MH and ML will be turned off in response to a user instruction. A notification signal Sg of logic H notifies that it has been determined that there is a sign that the power switches MH and ML will be turned off in response to a user instruction.

[0062] During the period from when the determination unit 90 outputs the notification signal Sg of logic H until the power switches MH and ML are actually turned off, discharge control is performed to discharge the second capacitor 15b. In this embodiment, as the discharge control, zero-axis current control is performed in the control process of the rotating electric machine 40, in which a zero-axis current is caused to flow through each of the phase windings 51U, 51V, and 51W. The zero-axis current is the total current of the phase currents flowing through each of the phase windings 51U, 51V, and 51W.

[0063] Specifically, the zero-axis command value calculation unit 91 turns off the changeover switches QH and QL and calculates the zero-axis current command value I0* during the period from when the notification signal Sg of logic H is input until the power switches MH and ML are actually turned off. The zero-axis current command value I0* is a command value for the zero-axis current to be flowed through the phase windings 51U, 51V, and 51W from the second terminals 51Ub, 51Vb, and 51Wb toward the first terminals 51Ua, 51Va, and 51Wa. The zero-axis command value calculation unit 91 outputs the calculated zero-axis current command value I0* to the current feedback unit 82.

[0064] The first conversion unit 81 calculates the d-axis current value Idr, the q-axis current value Iqr, and the zero-axis current value I0r based on the phase currents Iur, Ivr, and Iwr detected by the current sensor 63 and the electrical angle θr detected by the rotation angle sensor 64. The first conversion unit 81 calculates the sum of the phase currents Iur, Ivr, and Iwr as the zero-axis current value I0r. The first conversion unit 81 outputs the calculated d-axis current value Idr, q-axis current value Iqr, and zero-axis current value I0r to the current feedback unit 82. The first conversion unit 81 corresponds to a "current value calculation unit."

[0065] The current feedback unit 82 calculates a d-axis voltage command value Vd*, a q-axis voltage command value Vq*, and a zero-axis voltage command value V0* based on the d- and q-axis current command values ​​Id*, Iq*, and the zero-axis current command value I0*, as well as the d- and q-axis current values ​​Idr, Iqr, and the zero-axis current value I0r. The current feedback unit 82 calculates a zero-axis current deviation, which is the difference between the zero-axis current command value I0* and the zero-axis current value I0r, and calculates a zero-axis voltage command value V0* as a manipulated variable for feedback-controlling the calculated zero-axis current deviation to zero. The current feedback unit 82 outputs the calculated d-axis voltage command value Vd*, q-axis voltage command value Vq*, and zero-axis voltage command value V0* to the second conversion unit 83. The feedback control is, for example, proportional-plus-integral control.

[0066] The second conversion unit 83 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*, the zero-axis voltage command value V0*, and the electrical angle θr. As in the above-described case, the switch control unit 86 generates drive signals for the switches SUHa-SWLa and SUHb-SWLb of the inverters 20 and 30. In this embodiment, the d- and q-axis command value calculation unit 80, the first conversion unit 81, the switch control unit 86, and the zero-axis command value calculation unit 91 correspond to a "discharge control unit."

[0067] In the control process of the rotating electric machine 40 described above, switching control of the switches SUHa-SWLa and SUHb-SWLb is performed so that the zero-axis current flows from the second terminals 51Ub, 51Vb, and 51Wb of the respective phase windings 51U, 51V, and 51W toward the first terminals 51Ua, 51Va, and 51Wa of the respective phase windings 51U, 51V, and 51W. In this case, while driving the rotating electric machine 40, a current can be passed from the second capacitor 15b to the battery 10 via the respective phase windings 51U, 51V, and 51W. Therefore, the second capacitor 15b can be discharged while driving the rotating electric machine 40.

[0068] Fig. 6 shows a flowchart of the process executed by the control device 60. The process shown in Fig. 6 is repeatedly executed by the processor 60a of the control device 60, for example, at a predetermined control period.

[0069] In step S20, the determination unit 90 determines whether the rotation speed Nr (corresponding to the "speed parameter") of the rotor 41 is lower than a predetermined rotation speed determination value Nc (corresponding to the "parameter determination value"). For example, the rotation speed determination value Nc is a value for determining that the vehicle speed is low, and specifically, the rotation speed of the rotor 41 corresponding to a vehicle speed of less than 1 km / h, less than 5 km / h, or less than 10 km / h.

[0070] If a negative determination is made in step S20, the determination unit 90 determines that there is no indication that the power switches MH and ML will be turned off by a user instruction. In this case, the determination unit 90 outputs a notification signal Sg of logic L to the zero-axis command value calculation unit 91, and this processing ends. On the other hand, if a positive determination is made in step S20, the processing proceeds to step S21.

[0071] In step S21, the determination unit 90 determines whether the magnitude of the torque command value Trq* is lower than a predetermined torque determination value Trqc. For example, the determination in step S21 is performed to prevent an erroneous determination that there is a sign that the power switches MH and ML are about to be turned off when the vehicle is traveling slowly up a slope. For example, the torque determination value Trqc is a value near 0, specifically, 1%, 3%, or 5% of the rated torque of the rotating electric machine 40.

[0072] If the determination in step S21 is affirmative, the determination unit 90 determines that there is a sign that the power switches MH and ML will be turned off in response to a user instruction. In this case, the determination unit 90 outputs a notification signal Sg of logic H to the zero-axis command value calculation unit 91, and the process proceeds to step S22. On the other hand, if the determination in step S21 is negative, it determines that there is no sign that the power switches MH and ML will be turned off in response to a user instruction. In this case, the determination unit 90 outputs a notification signal Sg of logic L to the zero-axis command value calculation unit 91, and the process ends.

[0073] If it is determined that the rotation speed Nr of the rotor 41 is lower than the rotation speed determination value Nc, there is a possibility that the operation of the rotary electric machine 40 will soon be stopped and the user will turn off the start switch 70. As a result, there is a possibility that the power switches MH and ML will be turned off. Therefore, according to this embodiment, it is possible to appropriately determine whether there is a sign that the power switches MH and ML will be turned off in response to a user instruction.

[0074] The fact that the rotation speed Nr of the rotor 41 is determined to be lower than the rotation speed determination value Nc and that the torque command value Trq* is determined to be lower than the torque determination value Trqc indicates that the vehicle is likely to be traveling at a low speed on a level road surface, such as in a parking lot. In this case, the vehicle will soon be parked and the user may turn off the start switch 70. Therefore, by taking the torque of the rotating electric machine 40 into consideration, it is possible to accurately determine whether there is a sign that the power switches MH and ML will be turned off.

[0075] In step S22, the zero-axis command value calculation unit 91 turns off the changeover switches QH and QL. In step S23, zero-axis current control is performed. Specifically, the zero-axis command value calculation unit 91 calculates the zero-axis current command value I0*. The dq-axis command value calculation unit 80 calculates the d-axis and q-axis current command values ​​Id* and Iq*. The first conversion unit 81 calculates the d-axis current value Idr, the q-axis current value Iqr, and the zero-axis current value I0r. The current feedback unit 82, the second conversion unit 83, and the switch control unit 86 perform switching control of the switches SUHa to SWLa and SUHb to SWLb to control the calculated d-axis current value Idr, q-axis current value Iqr, and zero-axis current value I0r to the d-axis current command value Id*, q-axis current command value Iq*, and zero-axis current command value I0*.

[0076] In step S24, it is determined whether the start switch 70 has been turned off by the user. If the determination in step S24 is affirmative, the process proceeds to step S25. In step S25, the power switches MH and ML are turned off. In step S26, the capacitors 15a and 15b are discharged. For example, the capacitors 15a and 15b are discharged by controlling the switching of the switches SUHa-SWLa and SUHb-SWLb so that a d-axis current flows through the phase windings 51U, 51V, and 51W.

[0077] On the other hand, if the determination in step S24 is negative, the process proceeds to step S27. In step S27, it is determined whether the vehicle has started to move again. The determination of whether the vehicle has started to move again can be made by various methods. For example, it is determined that the vehicle has started to move again when the accelerator operation amount Ac detected by the accelerator sensor 72 becomes equal to or greater than a predetermined value.

[0078] If the determination in step S27 is affirmative, the process proceeds to step S28. In step S28, the second capacitor 15b is charged. For example, by turning on each of the selector switches QH and QL, current can be supplied from the battery 10 to the second capacitor 15b, thereby charging the second capacitor 15b. On the other hand, if the determination in step S27 is negative, the process returns to step S24.

[0079] Next, with reference to FIG. 7 , the effects of the above-described process will be described. In FIG. 7 , (a) shows the transitions of the first voltage V1r and the second voltage V2r, which is the voltage detected by the second voltage sensor 62, (b) shows the on / off state of the start switch 70, (c) shows the logic of the notification signal Sg, (d) shows the on / off state of each power switch MH, ML, (e) shows the on / off state of the positive-side selector switch QH, and (f) shows the on / off state of the negative-side selector switch QL. Here, it is assumed that the control system 100 is in H drive control before time t1. Therefore, before time t1, the second voltage V2r is equal to the terminal voltage VB of the battery 10.

[0080] At time t1, the determination unit 90 determines that there is a sign that the power switches MH and ML will be turned off in response to a user instruction. At time t2, the power switches MH and ML are actually turned off in response to a user instruction. During a post-discharge period Td after time t2, the capacitors 15a and 15b are discharged.

[0081] During a pre-discharge period Tp from time t1 to time t2, the zero-axis command value calculator 91 calculates the zero-axis current command value I0*. As a result, in the control process for the rotary electric machine 40, switching control of the switches SUHa-SWLa and SUHb-SWLb is performed so that the zero-axis current flows through the phase windings 51U, 51V, and 51W from the second terminals 51Ub, 51Vb, and 51Wb toward the first terminals 51Ua, 51Va, and 51Wa. This allows the second capacitor 15b to be pre-discharged before the power switches MH and ML are actually turned off, thereby reducing the amount of charge accumulated in the second capacitor 15b. As a result, the post-discharge period Td of the capacitors 15a and 15b can be shortened.

[0082] 8 shows an example of an operation for discharging the capacitors 15a and 15b in a comparative example. Unlike the present embodiment, the comparative example does not perform discharge control. In this case, at time t1 when the power switches MH and ML are turned off in response to a user instruction, the first voltage V1r and the second voltage V2r are set to the terminal voltage VB of the battery 10. Therefore, due to the large amount of charge stored in the capacitors 15a and 15b at time t1, the post-discharge period Td shown in FIG. 8 is longer than the post-discharge period Td shown in FIG. 7.

[0083] <Variation of the first embodiment> In step S20 of FIG. 6 , the determination unit 90 may determine whether the vehicle speed Vs (corresponding to the “speed parameter”) detected by the vehicle speed sensor 71, instead of the rotation speed Nr of the rotor 41, is lower than a predetermined vehicle speed determination value (corresponding to the “parameter determination value”).

[0084] In step S20 of FIG. 6, the determination unit 90 may determine whether the rotation speed Nr of the rotor 41 is lower than the rotation speed determination value Nc, and may also determine whether the vehicle speed Vs of the vehicle is lower than the vehicle speed determination value.

[0085] 6, the determination unit 90 may determine whether the accelerator operation amount Ac detected by the accelerator sensor 72 is lower than a predetermined operation amount determination value, instead of the torque command value Trq*. Even in this case, it is possible to accurately determine whether there is a sign that the power switches MH, ML will be turned off, similar to the determination process when the torque command value Trq* is used.

[0086] In step S21 of FIG. 6 , the determination unit 90 may determine whether the brake stroke Br of the brake stroke sensor 73 is higher than a predetermined brake determination value, instead of the torque command value Trq*. Determining that the rotation speed Nr of the rotor 41 is lower than the rotation speed determination value Nc and that the brake stroke Br is higher than the brake determination value indicates the possibility that the vehicle has parked in a parking space. In this case, there is a possibility that the power switches MH and ML will be turned off soon. Therefore, by taking the brake stroke Br into consideration, it is possible to accurately determine whether there are signs that the power switches MH and ML will be turned off.

[0087] In step S21 of FIG. 6, the determination unit 90 may perform at least two of the following determination processes: a determination process of whether the torque command value Trq* is lower than the torque determination value Trqc; a determination process of whether the accelerator operation amount Ac is lower than the operation amount determination value; and a determination process of whether the brake stroke Br is higher than the brake determination value.

[0088] In FIG. 6, the process of step S21 does not need to be performed.

[0089] 2, the zero-axis command value calculation unit 91 may acquire the second voltage V2r. In this case, in step S32 in FIG. 6, the zero-axis command value calculation unit 91 may stop the zero-axis current control if the second voltage V2r is reduced to 0 before the power switches MH and ML are turned off in response to a user instruction.

[0090] Second Embodiment A second embodiment will now be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as discharge control, boost control is performed in which the inverters 20 and 30 and the phase windings 51U, 51V, and 51W are operated as boost circuits.

[0091] 9, the determination unit 190 receives as input the rotation speed Nr calculated by the speed calculation unit 84, a signal SH indicating the shift position, a brake signal Ps indicating the operation status of the parking brake, the vehicle speed Vs detected by the vehicle speed sensor 71, and destination information and current position information transmitted from the navigation device 75. Based on the various input values, the determination unit 190 determines whether there is a sign that the power switches MH, ML will be turned off in response to a user instruction. The processing in the determination unit 190 will be described later.

[0092] In this embodiment, the discharge control unit 191 performs boost control as discharge control during the period from when the notification signal Sg of logic H is input until the power switches MH and ML are actually turned off. When performing boost control, the discharge control unit 191 turns off the selector switches QH and QL.

[0093] The discharge control unit 191 receives a first voltage V1r and a second voltage V2r. Based on the received first voltage V1r and second voltage V2r, the discharge control unit 191 calculates the duty ratio of the first lower arm switches SULa, SVLa, and SWLa of each phase. The duty ratio is the ratio Ton / Tsw of the on-period Ton of the first lower arm switches SULa, SVLa, and SWLa of each phase in one switching period Tsw. The discharge control unit 191 generates drive signals for turning on and off the first lower arm switches SULa, SVLa, and SWLa of each phase according to the calculated duty ratio. The discharge control unit 191 generates an OFF command for the first upper arm switches SUHa, SVHa, SWHa of each phase and the second lower arm switches SULb, SVLb, SWLb of each phase, and an ON command for the second upper arm switches SUHb, SVHb, SWHb of each phase.

[0094] The switches SUHa to SWLa and SUHb to SWLb are driven based on drive signals generated by a discharge control unit 191. In this case, in each phase, during the on period of the first lower arm switches SULa, SVLa, and SWLa, a current flows through a closed circuit including the second capacitor 15b, the second upper arm switches SUHb, SVHb, and SWHb, the windings 51U, 51V, and 51W, the first lower arm switches SULa, SVLa, and SWLa, the freewheel diode DL of the negative-side changeover switch QL, and the negative-side bus 12. As a result, the second capacitor 15b is discharged, and magnetic energy is stored in the windings 51U, 51V, and 51W in each phase.

[0095] On the other hand, in each phase, during the off period of the first lower arm switches SULa, SVLa, SWLa, a current flows through a closed circuit including the second capacitor 15b, the second upper arm switches SUHb, SVHb, SWHb, the windings 51U, 51V, 51W, the first upper arm diodes DUHa, DVHa, DWHa, the battery 10, the freewheel diode DL of the negative side changeover switch QL, and the negative side bus 12. This causes the second capacitor 15b to be discharged and the battery 10 to be charged.

[0096] By carrying out the above-described voltage boost control, the voltage of the second capacitor 15b is boosted, and the boosted voltage is supplied to the battery 10. This allows the second capacitor 15b to be discharged.

[0097] In this embodiment, the first upper-arm diodes DUHa, DVHa, and DWHa are turned on during the off periods of the first lower-arm switches SULa, SVLa, and SWLa in each phase. This allows for greater conduction loss than when the first upper-arm switches SUHa, SVHa, and SWHa in each phase are turned on. This makes it possible to realize a configuration suitable for discharging the second capacitor 15b by performing voltage step-up control. Note that the discharge control unit 191 may generate an on command for the first upper-arm switches SUHa, SVHa, and SWHa in each phase during the discharge control.

[0098] Fig. 10 shows a flowchart of the process executed by the control device 60. The process shown in Fig. 10 is repeatedly executed by the processor 60a of the control device 60, for example, at a predetermined control cycle.

[0099] If the determination in step S20 is affirmative, the process proceeds to step S31. In step S31, the determination unit 190 determines whether the current vehicle position is a parking lot or not based on the current position information of the navigation device 75 and map data.

[0100] For example, if the determination unit 190 determines that the current vehicle position is on a road stored in the map data of the navigation device 75, a negative determination is made in step S31. In this case, the determination unit 190 determines that there is no indication that the power switches MH and ML will be turned off by a user instruction. The determination unit 190 then outputs a notification signal Sg of logic L to the discharge control unit 191, and this process ends.

[0101] On the other hand, for example, if the current position information of the vehicle indicates a parking lot of a facility stored in the map data of the navigation device 75, or indicates the vehicle's home registered in the navigation device 75, the determination unit 190 makes a positive determination in step S31. In this case, the process proceeds to step S32.

[0102] In step S32, the determination unit 190 determines whether the parking brake is applied based on the brake signal Ps detected by the parking brake sensor 76. If the determination in step S32 is affirmative, the determination unit 190 determines that there is a sign that the power switches MH and ML will be turned off in response to a user instruction. In this case, the determination unit 190 outputs a notification signal Sg of logic H to the discharge control unit 191. The process then proceeds to step S33. On the other hand, if the determination in step S32 is negative, the determination unit 190 determines that there is no sign that the power switches MH and ML will be turned off in response to a user instruction. In this case, the determination unit 190 outputs a notification signal Sg of logic L to the discharge control unit 191, and the process ends.

[0103] The fact that the vehicle's current location is in a parking lot indicates that the vehicle is likely to be parked. In this case, there is a possibility that the power switches MH and ML will be turned off soon. Therefore, by taking into consideration the current location information and map data transmitted from the navigation device 75, it is possible to accurately determine whether there are any signs that the power switches MH and ML will be turned off.

[0104] The fact that the parking brake is applied indicates that the vehicle may be parked. In this case, there is a possibility that the power switches MH and ML may be turned off. Therefore, by taking into consideration the brake signal Ps detected by the parking brake sensor 76, it is possible to accurately determine whether there is a sign that the power switches MH and ML will be turned off.

[0105] In step S33, the discharge control unit 191 turns off the switches QH and QL. In step S34, the discharge control unit 191 performs the voltage boost control described above in Fig. 9 as the discharge control. The processes in steps S24 to S28 are the same as those in the first embodiment, and therefore will not be described here.

[0106] Next, the effects of the above-described process will be described with reference to Fig. 11. Figs. 11(a) to (f) correspond to Figs. 7(a) to (f). The explanations for times t1 and t2 in Fig. 11 are the same as those for times t1 and t2 in Fig. 7, and therefore will not be repeated.

[0107] During a pre-discharge period Tp from time t1 to time t2, the discharge control unit 191 performs discharge control to discharge the second capacitor 15b. In this embodiment, the discharge control unit 191 performs boost control with the selector switches QH and QL turned off. In this case, boost control can be performed for each phase, which allows the discharge current of the second capacitor 15b to be increased. This makes it possible to realize a configuration suitable for quickly discharging the second capacitor 15b. In FIG. 11 , the second voltage V2r is reduced to 0 during the pre-discharge period Tp. In this case, the discharge control unit 191 stops the boost control.

[0108] When the boost control is performed, current flows through each of the phase windings 51U, 51V, and 51W. In this case, torque may be generated by the rotary electric machine 40. In this regard, in this embodiment, the conditions for determining whether there is a sign that the power switches MH and ML will be turned off by a user instruction include whether the parking brake is activated. As a result, the boost control is performed while the parking brake is activated. As a result, rotation of the drive wheels 43 can be suppressed.

[0109] <Modification of the Second Embodiment> In step S32 of FIG. 10 , the determination unit 190 may determine whether the shift position detected by the shift position sensor 74 is in the P range and whether the parking brake is applied. This makes it possible to accurately determine whether the vehicle is parked. Therefore, it is possible to accurately determine whether there are any signs that the power switches MH and ML will be turned off.

[0110] In FIG. 10, the process of step S20 does not have to be performed.

[0111] Third Embodiment A third embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, Y drive control is performed as discharge control.

[0112] 12, destination information of the navigation device 75 and current vehicle position information are input to the determination unit 290. Based on the input destination information and current position information, the determination unit 290 determines whether there is a sign that the power switches MH and ML will be turned off in response to a user instruction. The processing in the determination unit 290 will be described later.

[0113] In this embodiment, the control device 60 includes a Y-drive command unit 291. The Y-drive command unit 291 outputs a command to select Y-drive control to the selection unit 85 during the period from when the notification signal Sg of logic H is input until the power switches MH and ML are actually turned off. When the selection unit 85 receives a command to select Y-drive control from the Y-drive command unit 291, the selection unit 85 selects Y-drive control regardless of the operating point of the rotating electric machine 40. In this case, the switch control unit 86 fixes the changeover switches QH and QL to OFF, fixes the second upper arm switches SUHb, SVHb, and SWHb of the second inverter 30 to ON, and fixes the second lower arm switches SULb, SVLb, and SWLb of the second inverter 30 to OFF. The switch control unit 86 then PWM-drives the switches SUHa to SWLa of the first inverter 20.

[0114] In the Y-drive control, the phase windings 51U, 51V, and 51W are Y-connected via the second upper arm switches SUHb, SVHb, and SWHb. In this case, the first end of the second capacitor 15b is electrically connected to the neutral point of the phase windings 51U, 51V, and 51W via the second upper arm switches SUHb, SVHb, and SWHb. Therefore, by performing the Y-drive control, the voltage of the second capacitor 15b is set to half the terminal voltage VB of the battery 10. In this embodiment, the selector 85, the switch control unit 86, and the Y-drive command unit 291 correspond to a "discharge control unit."

[0115] Fig. 13 shows a flowchart of the process executed by the control device 60. The process shown in Fig. 13 is repeatedly executed by the processor 60a of the control device 60, for example, at a predetermined control cycle.

[0116] In step S40, the determination unit 290 determines whether the current location of the vehicle is near the destination based on the input destination information and current position information. For example, the determination unit 290 determines that the current location of the vehicle is near the destination if the distance to the destination is within a predetermined distance. Alternatively, for example, the determination unit 290 determines that the current location of the vehicle is not near the destination if the distance to the destination is longer than the predetermined distance. The predetermined distance may be any distance that allows enough time for the voltage of the second capacitor 15b to decrease to approximately half the terminal voltage VB of the battery 10 by performing Y drive control. For example, the predetermined distance is less than 5 km, less than 3 km, less than 1 km, less than 500 m, less than 300 m, or less than 100 m.

[0117] If a negative determination is made in step S40, the determination unit 290 determines that there is no indication that the power switches MH and ML will be turned off by a user instruction. In this case, the determination unit 290 outputs a notification signal Sg of logic L to the Y drive command unit 291, and ends this process.

[0118] On the other hand, if the determination in step S40 is affirmative, the determination unit 290 determines that there is a sign that the power switches MH and ML will be turned off in response to a user instruction. In this case, the determination unit 290 outputs a notification signal Sg of logic H to the Y drive command unit 291. The Y drive command unit 291 outputs a command to select Y drive control to the selection unit 85. The selection unit 85 selects Y drive control. Then, the process proceeds to step S41.

[0119] In step S41, the switches QH and QL are turned off in the switch control unit 86. In step S42, Y drive control is executed in the switch control unit 86. The processes in steps S24 to S28 are the same as those in the first embodiment, and therefore will not be described here.

[0120] According to this embodiment, Y-drive control is executed as the discharge control. When the drive state of the control system 100 is switched from H-drive control to Y-drive control, the voltage of the second capacitor 15b can be reduced from the terminal voltage VB of the battery 10 to half of the terminal voltage VB while driving the rotating electric machine 40. Therefore, the second capacitor 15b can be discharged while driving the rotating electric machine 40.

[0121] If the current position of the vehicle is near the destination, there is a possibility that the vehicle operation will be terminated when the vehicle arrives at the destination. As a result, there is a possibility that the power switches MH and ML will be turned off. Therefore, according to this embodiment, it is possible to accurately determine whether or not there is a sign that the power switches MH and ML will be turned off. Furthermore, it is possible to ensure time for performing the Y drive control to discharge the second capacitor 15b during the period until the vehicle arrives at the destination. Therefore, it is possible to realize a configuration suitable for pre-discharging the second capacitor 15b before the power switches MH and ML are turned off.

[0122] Other Embodiments The above-described embodiments may be modified as follows.

[0123] 6, the positive-side changeover switch QH may be turned off and the negative-side changeover switch QL may be turned on in the zero-axis command value calculation unit 91. Even in this case, it is possible to perform the zero-axis current control in step S23.

[0124] 10, the positive electrode side changeover switch QH may be turned off and the negative electrode side changeover switch QL may be turned on in the discharge control unit 191. Even in this case, the discharge control unit 191 can perform the voltage boost control in step S34.

[0125] 13, the switch control unit 86 may turn off either one of the switches QH and QL. Even in this case, the switch control unit 86 can perform Y drive control in step S42.

[0126] For example, the switch control unit 86 may turn on the positive-side selector switch QH and turn off the negative-side selector switch QL. In this case, the second upper-arm switches SUHb, SVHb, and SWHb of the second inverter 30 are fixed to be off, and the second lower-arm switches SULb, SVLb, and SWLb of the second inverter 30 are fixed to be on. Then, the switch control unit 86 controls the switches SUHa to SWLa of the first inverter 20 to be PWM-driven. Even in this case, Y-drive control can be performed.

[0127] In step S23 of Fig. 6, Y drive control may be performed instead of the zero-axis current control. In this case, the processor 60a may implement the functions of the Y drive command unit 291, the selection unit 85, and the switch control unit 86 shown in Fig. 12.

[0128] In step S42 of Fig. 13, zero-axis current control may be performed instead of Y-drive control. In this case, the processor 60a may implement the functions of the dq-axis command value calculation unit 80, the first conversion unit 81, the current feedback unit 82, the second conversion unit 83, the switch control unit 86, and the zero-axis command value calculation unit 91 shown in Fig. 2.

[0129] In the first embodiment, the control system 100 may include only one of the changeover switches QL, QL. For example, if the control system 100 includes only the positive changeover switch QH of the changeover switches QH, QL, the zero-axis command value calculation unit 91 may turn off the positive changeover switch QH in step S22 of FIG.

[0130] In the second embodiment, the control system 100 may include only the positive-side selector switch QH of the selector switches QH and QL. In this case, in step S33 of FIG. 10 , the discharge control unit 191 turns off the positive-side selector switch QH.

[0131] In the third embodiment, the control system 100 may include only one of the selector switches QL and QL. For example, if the control system 100 includes only the positive selector switch QH of the selector switches QH and QL, the switch control unit 86 may turn off the positive selector switch QH in step S41 of FIG. 13. Even in this case, the Y drive control can be performed.

[0132] Furthermore, for example, if the control system 100 is provided with only the negative-side changeover switch QL of the changeover switches QH, QL, then in step S41 of Fig. 13, the switch control unit 86 may turn off the negative-side changeover switch QL. In step S42, the switch control unit 86 may fix the second upper arm switches SUHb, SVHb, SWHb of the second inverter 30 to the off state, and fix the second lower arm switches SULb, SVLb, SWLb of the second inverter 30 to the on state. Even in this case, it is possible to perform Y-drive control.

[0133] The control system 100 may be provided with either one of the power switches MH and ML.

[0134] The series connection of the precharge switch and resistor may be connected in parallel to the positive power switch MH instead of being connected in parallel to the negative power switch ML.

[0135] The DC power source is not limited to a battery, and may be, for example, a fuel cell.

[0136] The rotating electric machine is not limited to a three-phase one, but may be a two-phase one or a four-phase or more phase one.

[0137] The semiconductor switches constituting the first inverter and the second inverter are not limited to IGBTs, but may be, for example, N-channel MOSFETs. In this case, the high-potential terminal of the switch is the drain, and the low-potential terminal is the source. Each switch also has a body diode.

[0138] The control system may include relays as the positive electrode side changeover switch QH and the negative electrode side changeover switch QL.

[0139] 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.

[0140] The control device and method described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control device and method described herein may be implemented by a special-purpose computer configured with a processor comprising one or more dedicated hardware logic circuits. Alternatively, the control device and method described herein may be implemented by one or more special-purpose computers configured with a combination of a processor and memory programmed to execute one or more functions and 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 to be executed by a computer.

[0141] 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 windings (51U, 51V, 51W) of multiple phases, a first inverter (20) having as many series-connected first upper arm switches (SUHa, SVHa, SWHa) and first lower arm switches (SUL a, SVL a, SWL a) as 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 series-connected second upper arm switches (SUHb, SVHb, SWHb) and second lower arm switches (SULb, SVLb, SWLb) as many as the number of phases, a positive bus bar (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 bus bar (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, a switching switch (QH, QL) provided on at least one of the positive bus bar and the negative bus bar, a first capacitor (15a) connected in parallel to the series connection of the first upper arm switches and the first lower arm switches, a second capacitor (15b) connected in parallel to the series connection of the second upper arm switches and the second lower arm switches, and a power switch (MH, ML) provided in the path electrically connecting the first inverter and the DC power supply. A control device for a rotating electrical machine applied to a system (100), wherein in each phase, the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch are electrically connected to the first end of the winding, in each phase, the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch are electrically connected to the second end of the winding, a determination unit (90, 190, 290) for determining whether there is a sign that the power switch is turned off according to an instruction from a user of the system, and a discharge control unit (80, 81, 85,A control device for a rotating electrical machine, comprising (86, 91, 191, 291).

2. The discharge control units (85, 86, 291) perform, as the discharge control, when the changeover switch is off, turning on and fixing each phase's second upper arm switch or each phase's second lower arm switch, and performing switching control of each phase's first upper arm switch and each phase's first lower arm switch. The control device for a rotating electrical machine according to claim 1.

3. The discharge control unit, as a processing unit for performing the discharge control, includes: a zero-axis command value calculation unit (91) that calculates a zero-axis current command value, which is a command value of a zero-axis current flowing through the winding of each phase from the second end side toward the first end side; a dq-axis command value calculation unit (80) that calculates a d-axis current command value and a q-axis current command value for the winding of each phase based on a torque command value for commanding the torque of the rotating electrical machine; a current value calculation unit (81) that calculates a d-axis current value, a q-axis current value, and a zero-axis current value flowing through the winding of each phase; and a switch control unit (86) that performs switching control of the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch in a state where the changeover switch is off to control the calculated d-axis current value, q-axis current value, and zero-axis current value to the d-axis current command value, q-axis current command value, and zero-axis current command value. The control device for a rotating electrical machine according to claim 1.

4. The system is mounted on a vehicle that can be moved using the rotating electrical machine as a power source. The determination unit (90) determines that there is a sign that the power switch will be turned off when it is determined that at least one of the speed parameters, which is either the rotational speed of the rotor (41) of the rotating electrical machine or the vehicle speed of the vehicle, is lower than a parameter determination value. The control device for a rotating electrical machine according to any one of claims 1 to 3.

5. The determination unit determines that there is a sign that the power switch will be turned off when it is determined that the acquired rotational speed of the rotor is lower than the parameter determination value and the torque of the rotating electrical machine is lower than a torque determination value. The control device for a rotating electrical machine according to claim 4.

6. The system is mounted on a vehicle movable using the rotating electrical machine as a power source, and when the determination unit (290) determines that the current position of the vehicle is around the destination based on the destination information of the navigation device (75) mounted on the vehicle and the current position information of the vehicle, it determines that there is a sign that the power switch will be turned off. The control device for a rotating electrical machine according to claim 2 or 3.

7. The system includes, as the changeover switch, a positive electrode side changeover switch (QH) provided on the positive electrode side bus bar, and the discharge control unit (191) performs control to turn off the positive electrode side changeover switch, boost the voltage of the second capacitor, and supply the boosted voltage to the DC power source by turning on and off the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch as the discharge control. The control device for a rotating electrical machine according to claim 1.

8. The system is mounted on a vehicle movable using the rotating electrical machine as a power source, and when the determination unit (190) determines that a brake signal notifying the operating state of the parking brake provided on the vehicle indicates that the parking brake is in the operating state, it determines that there is a sign that the power switch will be turned off. The control device for a rotating electrical machine according to claim 7.

9. When the determination unit determines that the brake signal indicates that the parking brake is in the operating state and the current position information of the navigation device (75) mounted on the vehicle indicates that the vehicle is in a parking lot, it determines that there is a sign that the power switch will be turned off. The control device for a rotating electrical machine according to claim 8.

10. A rotating electrical machine (40) having windings (51U, 51V, 51W) of multiple phases, a first inverter (20) having, for the number of phases, a first upper arm switch (SUHa, SVHa, SWHa) and a first lower arm switch (SULa, SVLa, SWLa) connected in series, and a series connection of the first upper arm switch and the first lower arm switch being connected in parallel to a DC power supply (10), a second inverter (30) having, for the number of phases, a second upper arm switch (SUHb, SVHb, SWHb) and a second lower arm switch (SULb, SVLb, SWLb) connected in series, a positive bus bar (11) electrically connecting the high-potential side terminals of the first upper arm switch and the second upper arm switch in each phase, a negative bus bar (12) electrically connecting the low-potential side terminals of the first lower arm switch and the second lower arm switch in each phase, a switching switch (QH, QL) provided on at least one of the positive bus bar and the negative bus bar, a first capacitor (15a) connected in parallel to the series connection of the first upper arm switch and the first lower arm switch, a second capacitor (15b) connected in parallel to the series connection of the second upper arm switch and the second lower arm switch, and a power switch (MH,A program applied to a system (100) comprising: a processor (60a); and a power switch. 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 the first end of the winding. 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 the second end of the winding. The program causes the processor (60a) to execute a determination process for determining whether there is a sign that the power switch is to be turned off according to an instruction from a user of the system, and a control process for performing discharge control to discharge the second capacitor by controlling the changeover switch, the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch during a period from when it is determined that there is a sign that the power switch is to be turned off until the power switch is turned off.

11. A rotating electrical machine (40) having windings (51U, 51V, 51W) of multiple phases, a first inverter (20) having as many series-connected first upper arm switches (SUHa, SVHa, SWHa) and first lower arm switches (SULa, SVLa, SWLa) as the number of phases, and a series connection of the first upper arm switch and the first lower arm switch being connected in parallel to a DC power supply (10), a second inverter (30) having as many series-connected second upper arm switches (SUHb, SVHb, SWHb) and second lower arm switches (SULb, SVLb, SWLb) as the number of phases, a positive bus bar (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 bus bar (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, a switching switch (QH, QL) provided on at least one of the positive bus bar and the negative bus bar, a first capacitor (15a) connected in parallel to the series connection of the first upper arm switch and the first lower arm switch, a second capacitor (15b) connected in parallel to the series connection of the second upper arm switch and the second lower arm switch, and a power switch (MH, ML) provided in a path electrically connecting the first inverter and the DC power supply. A control method for a rotating electrical machine applied to a system (100) comprising: in each phase, the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch are electrically connected to the first end of the winding; in each phase, the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch are electrically connected to the second end of the winding; a determination step of determining whether there is a sign that the power switch is turned off according to an instruction from a user of the system; and a control step of performing discharge control to discharge the second capacitor by controlling the switching switch, the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch during a period from when it is determined that there is a sign that the power switch is turned off until the power switch is turned off.

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