Rotary electric machine control device, program, and control method

Abstract

A control device (70) is applied to a system (100) comprising: a rotary electric machine (40); a first inverter (20) having a series connection body of first upper arm switches (SUHa-SWHa) and first lower arm switches (SULa-SWLa); a second inverter (30) having a series connection body of second upper arm switches (SUHb-SWHb) and second lower arm switches (SULb-SWLb); and changeover switches (QH, QL). The control device sets Y drive control or H drive control as a control mode of the arm switches of the first and second inverters. When it is determined that a short-circuit abnormality has occurred in any of the arm switches of the first and second inverters during execution of the Y drive control, the control device performs ON control of the changeover switch and then performs OFF control of a target switch that is an arm switch in which the short-circuit abnormality has not occurred among the series connection bodies including the arm switch in which the short-circuit abnormality has occurred.

Description

Control device, program, and control method for a rotating electric machine Cross-reference to related applications

[0001] The present application is based on Japanese Patent Application No. 2025-041710 filed on March 14, 2025, and the content thereof is incorporated herein by reference.

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

[0003] Conventionally, as described, for example, in Patent Document 1, a system that controls a rotating electric machine using two inverters is known. A first end of a plurality of phases of armature windings provided in the rotating electric machine is connected to a first inverter. Further, a second end of the plurality of phases of armature windings is connected to a second inverter. A changeover switch is provided in a path connecting the first inverter and the second inverter. The system controls the rotating electric machine by switching-controlling arm switches included in the first and second inverters in accordance with the on / off state of the changeover switch.

[0004] When a short-circuit abnormality occurs in an arm switch of the first or second inverter, if a target switch, which is an arm switch in which no short-circuit abnormality has occurred among series-connected bodies including the arm switch in which the short-circuit abnormality has occurred, is controlled to be on, a short-circuit current flows through the target switch. In this case, the short-circuit current may exceed the short-circuit withstand capability of the target switch, possibly causing a short-circuit abnormality in the target switch. In view of this, the system blocks the short-circuit current flowing through the target switch by performing off-control on the target switch to block the short-circuit current.

[0005] Japanese Unexamined Patent Publication No. 2017-175747

[0006] However, in the case of the above-described configuration, a surge voltage resulting from the off-control of the target switch may exceed the withstand voltage of the target switch, possibly causing a short-circuit abnormality in the target switch.

[0007] A main object of the present disclosure is to provide a control device, a program, and a control method for a rotating electric machine that appropriately protect a target switch.

[0008] This disclosure relates to a system comprising: a rotating electric machine having multiple phase armature windings; a first inverter having a series connection of a first upper arm switch and a first lower arm switch equal to the number of phases of the armature windings; a first capacitor connected in parallel to the first inverter; a DC power supply connected in parallel to the first inverter; a second inverter having a series connection of a second upper arm switch and a second lower arm switch equal to the number of phases of the armature windings; a second capacitor connected in parallel to the second inverter; a high-potential path connecting the high-potential terminal of the first upper arm switch and the high-potential terminal of the second upper arm switch; a low-potential path connecting the low-potential terminal of the first lower arm switch and the low-potential terminal of the second lower arm switch; and a changeover switch provided in at least one of the high-potential path and the low-potential path for electrically connecting or disconnecting the first inverter and the second inverter. The first end of the armature winding is connected to the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch, and the second end of the armature winding is connected to the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch. The control device for a rotating electric machine applied to the system comprises: a setting unit for setting Y-drive control or H-drive control as the control mode for the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch; a control unit for turning the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch on and off based on the control mode set by the setting unit; and a determination unit for determining a short-circuit abnormality of the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, wherein the Y-drive control is This control involves turning on the second upper arm switch and turning off the second lower arm switch while the changeover switch is in the off state, or turning on the second lower arm switch and turning off the second upper arm switch while the changeover switch is in the off state, and also turning on and off the first upper arm switch and the first lower arm switch.The H drive control is a control that turns the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch on and off while the changeover switch is turned on. If the determination unit determines that a short circuit has occurred in any of the first upper arm switch, the first lower arm switch, the second upper arm switch, or the second lower arm switch while the Y drive control is being executed, the control unit turns on the changeover switch and then turns off the target switch, which is an arm switch among the series connection that includes the arm switch where the short circuit occurred, that is not the short circuit.

[0009] The control unit turns on the changeover switch when the detection unit detects a short circuit abnormality. This allows current to flow bidirectionally from one side of the first capacitor to the other side of the second capacitor via the changeover switch. In this case, the current flowing from the first capacitor to the target switch also flows to the second capacitor via the changeover switch. As a result, the current flowing from the first capacitor to the target switch is reduced.

[0010] This reduces the surge voltage caused by the current flowing from the first capacitor to the target switch when the target switch is controlled to be turned off. As a result, it is possible to suppress situations where the surge voltage exceeds the withstand voltage of the target switch, and the target switch can be protected from short-circuit current and surge voltage.

[0011] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer from the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is an overall configuration diagram of the system according to the first embodiment; Figure 2 is a block diagram of the control processing performed by the control device; Figure 3 is a diagram showing the control mode of Y drive control; Figure 4 is a diagram showing the control mode of H drive control; Figure 5 is a flowchart showing the procedure of the target switch protection processing according to the first embodiment; Figure 6 is a diagram showing an example of the target switch protection processing; Figure 7 is a diagram showing an example of the target switch protection processing; Figure 8 is a diagram showing an example of the target switch protection processing; Figure 9 is a diagram showing an example of the target switch protection processing; Figure 10 is an overall configuration diagram of the system according to a modification of the first embodiment; Figure 11 is a diagram showing the control mode of Y drive control according to a modification of the first embodiment; and Figure 12 is a flowchart showing the procedure of the target switch protection processing according to the second embodiment.

[0012] <First Embodiment> Hereinafter, a first embodiment of the control device according to the present disclosure will be described with reference to the drawings. In this embodiment, the control device is applied to a system installed in an electric vehicle such as an electric vehicle or a hybrid vehicle.

[0013] First, the overall configuration of the system 100 will be explained using Figure 1. As shown in Figure 1, the system 100 includes a storage battery 10 which is a DC power source, a first inverter 20 which converts the DC current from the storage battery 10 to AC current, a second inverter 30 which converts the DC current from the storage battery 10 to AC current, a high-potential path 11 and a low-potential path 12. The storage battery 10 is, for example, a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery.

[0014] The first inverter 20 is equipped with three series connections (specifically, U-phase, V-phase, and W-phase) of first upper arm switches SUHa, SVHa, SWHa and first lower arm switches SULa, SVLa, SWLa. The second inverter 30 is equipped with three series connections (specifically, U-phase, V-phase, and W-phase) of second upper arm switches SUHb, SVHb, SWHb and second lower arm switches SULb, SVLb, SWLb. The positive terminal of the battery 10 is connected to the high-potential side terminal of the first upper arm switches SUHa, SVHa, SWHa for each phase. The negative terminal of the battery 10 is connected to the low-potential side terminal of the first lower arm switches SULa, SVLa, SWLa for each phase.

[0015] In this embodiment, the switches SUHa to SWLb of the first and second inverters 20 and 30 are semiconductor switching elements, more specifically, IGBTs. In this case, the high-potential terminal of each switch SUHa to SWLb in the first and second inverters 20 and 30 is the collector, and the low-potential terminal is the emitter. Freewheeling diodes are connected in antiparallel to each switch SUHa to SWLb of the first and second inverters 20 and 30. More specifically, the first upper arm diodes DUHa, DVHa, and DWHa of the U, V, and W phases are connected in antiparallel to the first upper arm switches SUHa, SVHa, and SWHa of the U, V, and W phases, and the first lower arm diodes DULa, DVLa, and DWLa of the U, V, and W phases are connected in antiparallel to the first lower arm switches SULa, SVLa, and SWLa of the U, V, and W phases. The U, V, W phase second upper arm switches SUHb, SVHb, and SWHb are connected in antiparallel to the U, V, W phase second upper arm diodes DUHb, DVHb, and DWHb, respectively, and the U, V, W phase second lower arm switches SULb, SVLb, and SWLb are connected in antiparallel to the U, V, W phase second lower arm diodes DULb, DVLb, and DWLb, respectively.

[0016] The high-potential path 11 and the low-potential path 12 are electrical paths such as busbars. The collectors of the first and second upper arm switches SUHa to SWHa and SUHb to SWHb are connected to the high-potential path 11. The emitters of the first and second lower arm switches SULa to SWLa and SULb to SWLb are connected to the low-potential path 12.

[0017] The system 100 includes a rotating electric machine 40 for driving an electric vehicle. The rotating electric machine 40 is connected to first and second inverters 20 and 30. The first and second inverters 20 and 30 are power converters that convert DC power supplied from the storage battery 10 into AC power and supply it to the rotating electric machine 40. In this embodiment, the first and second inverters 20 and 30 convert DC power into three-phase AC power and supply it to the rotating electric machine 40.

[0018] The rotating electric machine 40 comprises a rotor 41 and a stator 50. In this embodiment, the rotating electric machine 40 is a permanent magnet field type synchronous machine. The rotor 41 is equipped with permanent magnets 42 (for example, neodymium magnets) as field poles. The rotor 41 is capable of transmitting power to the drive wheels of the vehicle. Therefore, the rotating electric machine 40 becomes a source of torque that drives the electric vehicle.

[0019] The stator 50 is equipped with armature windings: a U-phase winding 51U, a V-phase winding 51V, and a W-phase winding 51W. Each of the phase windings 51U, 51V, and 51W is positioned in the stator core that constitutes the stator 50, offset by 120° in electrical angle. Each of the phase windings 51U, 51V, and 51W is an open winding.

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

[0021] System 100 includes a first capacitor 15 and a second capacitor 16. The first and second capacitors 15 and 16 function as smoothing capacitors. The first capacitor 15 is connected in parallel to the series connection of the first upper and lower arm switches SUHa to SWLa in each phase of the first inverter 20. The second capacitor 16 is connected in parallel to the series connection of the second upper and lower arm switches SUHb to SWLb in each phase of the second inverter 30.

[0022] The system 100 includes a power switch 14. Specifically, the power switch 14 connects the positive terminal of the battery 10 to the collectors of the first upper arm switches SUHa to SWHa in each phase. In this embodiment, the power switch 14 is a mechanical relay. However, the power switch 14 is not limited to a mechanical relay; for example, it may be a semiconductor switching element.

[0023] When the power switch 14 is turned on, it electrically connects the battery 10 to the collectors of the first upper arm switches SUHa to SWHa for each phase. Conversely, when the power switch 14 is turned off, it electrically disconnects the battery 10 from the collectors of the first upper arm switches SUHa to SWHa for each phase.

[0024] System 100 includes a changeover switch QH. The changeover switch QH is located in the high-potential path 11. In this embodiment, the changeover switch QH is a semiconductor switching element, more specifically, an N-channel MOSFET. In this case, the changeover switch QH has a body diode DH.

[0025] Specifically, the drain of the changeover switch QH is connected to the first inverter 20, and the source of the changeover switch QH is connected to the second inverter 30. When the changeover switch QH is turned on, it electrically connects the collectors of the first upper arm switches SUHa to SWHa in each phase to the collectors of the second upper arm switches SUHb to SWHb in each phase. On the other hand, when the changeover switch QH is turned off, it electrically disconnects the collectors of the first upper arm switches SUHa to SWHa in each phase from the collectors of the second upper arm switches SUHb to SWHb in each phase.

[0026] System 100 is equipped with various sensors for detecting the state of System 100. Specifically, System 100 includes a first current sensor 60, a second current sensor 61, and a third current sensor 62. The first current sensor 60 detects the current flowing through each phase winding 51U to 51W. The value detected by the first current sensor 60 is input to the control device 70 provided in System 100.

[0027] The second current sensor 61 detects the current flowing between the first capacitor 15 and the collectors of the first upper arm switches SUHa to SWHa in each phase. The current flowing from the first capacitor 15 to the first inverter 20 is defined as positive, and the current flowing from the first inverter 20 to the first capacitor 15 is defined as negative. The value detected by the second current sensor 61 is input to the control device 70.

[0028] The third current sensor 62 detects the current flowing between the second capacitor 16 and the collectors of the second upper arm switches SUHb to SWHb in each phase. The current flowing from the second capacitor 16 to the second inverter 30 is defined as positive, and the current flowing from the second inverter 30 to the second capacitor 16 is defined as negative. The value detected by the third current sensor 62 is input to the control device 70.

[0029] The system 100 is equipped with a rotation angle sensor 63. The rotation angle sensor 63 is, for example, a resolver, which detects the electrical angle θr of the rotor 41. The value detected by the rotation angle sensor 63 is input to the control device 70.

[0030] The system 100 is equipped with a power supply voltage sensor 64. The power supply voltage sensor 64 detects the voltage across the terminals of the first capacitor 15. The value detected by the power supply voltage sensor 64 is input to the control device 70.

[0031] The system 100 is equipped with a state detection sensor 65 that detects the state of each switch SUHa to SWLb. The state detection sensor 65 detects the terminal voltage of each switch SUHa to SWLb (specifically, the collector-emitter voltage), the current flowing through each switch SUHa to SWLb (specifically, the collector current), and the temperature of each switch SUHa to SWLb. The values ​​detected by the state detection sensor 65 are input to the control device 70.

[0032] The control device 70 is an electronic control unit (ECU) that performs various controls on the system 100, and comprises a processor 71 and a memory unit 72 as hardware. In the control device 70, the processor 71 and the memory unit 72 are connected to each other via a communication bus 73. In the system 100, each in-vehicle device can be controlled by an ECU corresponding to each in-vehicle device. However, for convenience, Figure 1 shows multiple ECUs as a single control device 70.

[0033] The memory unit 72 includes memory and storage as hardware. The memory is a storage device for storing data used for processing by the control device 70. The memory provides the processor 71 with a temporary workspace for use when the processor 71 is performing processing. The memory includes, for example, ROM or RAM. The storage is a storage device that stores various programs and data for the processor 71 to read and execute, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or flash memory. The storage stores program information for processing shown in Figure 2, which will be described later.

[0034] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit 72. The recording medium is, for example, a USB memory stick, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as OTA (Over The Air), is installed in the storage unit 72.

[0035] Next, the control process for the rotating electric machine 40, executed by the control device 70, is shown using the block diagram in Figure 2. The control process for the rotating electric machine 40 is a control process to determine whether the drive state of the system 100 is Y drive control or H drive control, which will be described later. The control device 70 includes a command value calculation unit 80, a two-phase conversion unit 81, and a current feedback unit 82.

[0036] The command value calculation unit 80 calculates the d-axis current command value Id* and the q-axis current command value Iq* in the dq coordinate system based on the command torque Trq* received from a control device higher than the control device 70.

[0037] The two-phase 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 first current sensor 60 and the electrical angle θr detected by the rotation angle sensor 63.

[0038] The current feedback unit 82 calculates the d-axis voltage command value Vd* and the q-axis voltage command value Vq* based on the d and q-axis current command values ​​Id* and Iq* input from the command value calculation unit 80 and the d and q-axis current values ​​Idr and Iqr input from the two-phase conversion unit 81. Specifically, the current feedback unit 82 calculates 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 the d-axis voltage command value Vd* as an manipulated variable for feedback control to set the calculated d-axis current deviation to zero. The current feedback unit 82 calculates 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 the q-axis voltage command value Vq* as an manipulated variable for feedback control to set the calculated q-axis current deviation to zero. The feedback control is, for example, proportional-integral control.

[0039] The control device 70 includes a three-phase conversion unit 83 and a speed calculation unit 84.

[0040] The three-phase conversion unit 83 calculates U-phase, V-phase, and W-phase voltage command values Vu*, Vv*, Vw* based on d-axis and q-axis voltage command values Vd*, Vq* and the electrical angle θr. The U-phase, V-phase, and W-phase voltage command values Vu*, Vv*, Vw* are command values for voltages applied to the U-phase, V-phase, and W-phase windings 51U, 51V, 51W, respectively.

[0041] The speed calculation unit 84 calculates the rotation speed Nr of the rotor 41 based on the electrical angle θr detected by the rotation angle sensor 63.

[0042] The control device 70 includes a setting unit 85 that selects whether the driving state of the system 100 should be Y-drive control or H-drive control.

[0043] In the present embodiment, the setting unit 85 selects whether to adopt Y-drive control or H-drive control based on the operating point of the rotating electric machine 40 determined by the calculated rotation speed Nr and command torque Trq*, and control map information. The control map information is information in which a Y-drive control region and an H-drive control region are defined in association with the rotation speed Nr and the command torque Trq*. The control map information is stored in the storage unit 72.

[0044] The setting unit 85 generates drive signals for the respective switches SUHa to SWLb of the first and second inverters 20, 30. The drive signals consist of ON commands and OFF commands for the switches.

[0045] Specifically, the setting unit 85 calculates U-phase, V-phase, and W-phase normalized command values Dutyu, Dutyv, Dutyw obtained by normalizing the U-phase, V-phase, and W-phase voltage command values Vu*, Vv*, Vw* with the power supply voltage Vsr, which is the voltage detected by the power supply voltage sensor 64. More specifically, the U-phase, V-phase, and W-phase normalized command values Dutyu, Dutyv, Dutyw are values obtained by dividing the U-phase, V-phase, and W-phase voltage command values Vu*, Vv*, Vw* by one half of the power supply voltage Vsr.

[0046] When Y-drive control is selected, the setting unit 85 turns off the changeover switch QH and performs control to PWM-drive each of the switches SUHa to SWLa of the first inverter 20 as Y-drive control, as shown in FIG. 3. In addition, the setting unit 85 keeps the U-phase, V-phase, and W-phase second upper arm switches SUHb to SWHb (hereinafter referred to as neutral point switches) fixed in an on state, and keeps the U-phase, V-phase, and W-phase second lower arm switches SULb to SWLb fixed in an off state. As a result, the phase windings 51U, 51V, 51W are star-connected via the second inverter 30.

[0047] The setting unit 85 generates drive signals for the switches SUHa to SWLa of the first inverter 20 based on a comparison between the U-phase, V-phase, and W-phase normalized command values Dutyu, Dutyv, Dutyw and the carrier signal Sgc. The carrier signal Sgc is, for example, a triangular wave signal having equal gradual increase speed and gradual decrease speed.

[0048] On the other hand, when H-drive control is selected, the setting unit 85 turns on the changeover switch QH as H-drive control, as shown in FIG. 4, performs PWM driving on each of the switches SUHa to SWLa of the first inverter 20, and also performs PWM driving on each of the switches SUHb to SWLb of the second inverter 30.

[0049] More specifically, the setting unit 85 generates drive signals for the switches SUHa to SWLa of the first inverter 20 based on a magnitude comparison between the U-phase to W-phase normalized command values Dutyu to Dutyw and the first carrier signal Sg1, in the same manner as in the case of Y-drive control. The setting unit 85 generates drive signals for the switches SUHb to SWLb of the second inverter 30 based on a magnitude comparison between the U-phase to W-phase normalized command values Dutyu to Dutyw and the second carrier signal Sg2, in the same manner as in the case of Y-drive control. The first carrier signal Sg1 and the second carrier signal Sg2 are, for example, triangular wave signals having equal gradual increase speed and gradual decrease speed. The frequency, amplitude, and fluctuation center value of the second carrier signal Sg2 are the same as those of the first carrier signal Sg1. In addition, the phase difference between the first carrier signal Sg1 and the second carrier signal Sg2 is 180°. In the present embodiment, the frequency of the first carrier signal Sg1 and the second carrier signal Sg2 used in H-drive control is the same as the frequency of the carrier signal Sgc used in Y-drive control.

[0050] The control device 70 includes a switch control unit 86 that controls the switches SUHa to SWLb of the first and second inverters 20 and 30 based on the drive signals generated by the setting unit 85.

[0051] The switch control unit 86 controls the charge and discharge current of the gates of switches SUHa to SWLb of the first and second inverters 20 and 30 based on the generated drive signal. This controls the on or off state of switches SUHa to SWLb of the first and second inverters 20 and 30 according to the drive signal.

[0052] In H drive control, the switching patterns of switches SUHa to SWLb of the first and second inverters 20 and 30, which are switched according to the drive signal, are shifted in phase by 120° in electrical angle for each phase. Similarly, in Y drive control, the switching patterns of switches SUHa to SWLa of the first inverter 20, which are switched according to the drive signal, are shifted in phase by 120° in electrical angle for each phase.

[0053] In the Y-drive control shown in Figure 3, if one arm switch experiences a short-circuit failure (corresponding to a "short-circuit abnormality"), and the other arm switch in the series connection including the short-circuited switch (hereinafter referred to as the "target switch") is turned ON, a short-circuit current will flow through the target switch. In this case, there is a concern that the short-circuit withstand capability of the target switch will be exceeded, causing the target switch to fail.

[0054] One known method for protecting a target switch from short-circuit current is to control the switch to the "off" state, thereby preventing the short-circuit current from flowing through it. However, this off-control to prevent the short-circuit current can generate a surge voltage. In this case, there is a concern that the surge voltage may exceed the voltage rating of the target switch, potentially causing it to fail.

[0055] As shown in Figure 2 above, the control device 70 includes a determination unit 87 that determines whether or not a short-circuit current is flowing through any of the series connections. In this embodiment, the determination unit 87 receives the detection value from the state detection sensor 65.

[0056] If the determination unit 87 determines that a short-circuit fault has occurred in any of the switches SUHa to SWLb, it performs the target switch protection process described later.

[0057] Next, the target switch protection process, which is a characteristic configuration of this embodiment, will be explained using the flowchart in Figure 5. This process protects the target switch from short-circuit current and surge voltage.

[0058] In step S10, the control device 70 determines whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb. An example of a method for determining whether or not a short-circuit current is flowing is described below.

[0059] The control device 70 determines whether the detected terminal voltage of each switch SUHa to SWLb that is in ON control is higher than the voltage threshold. Specifically, the control device 70 determines that the switch among the switches SUHa to SWLb that is in ON control whose detected terminal voltage is higher than the voltage threshold is the target switch, and determines that a short-circuit current is flowing through the target switch. On the other hand, if the control device 70 determines that the detected terminal voltage of each switch SUHa to SWLb that is in ON control is below the voltage threshold, it determines that there are no faulty switches and that no short-circuit current is flowing through each switch SUHa to SWLb.

[0060] If the control device 70 determines in step S10 that the result is negative, it terminates the target switch protection process.

[0061] If the control device 70 determines that step S10 is positive, it proceeds to step S11. In step S11, the control device 70 determines whether or not the changeover switch QH is in the OFF state. The process in step S11 is to determine whether the system 100 is in the Y drive control state or the H drive control state. If the control device 70 determines that step S11 is negative, it proceeds to step S14.

[0062] If the control device 70 determines that step S11 is positive, it proceeds to step S12. In step S12, the control device 70 switches the changeover switch QH to ON control. As a result, the current that previously flowed only in one direction through the body diode DH in the high-potential path 11 now flows bidirectionally through the changeover switch QH. In this case, the current that was flowing from the first capacitor 15 to the target switch now flows to the second capacitor 16 side through the changeover switch QH. As a result, the current flowing from the storage battery 10 and the first capacitor 15 to the target switch can be reduced. After that, the process proceeds to step S13.

[0063] In step S13, the control device 70 keeps the neutral point switches, U, V, and W phase second upper arm switches SUHb to SWHb, in the ON position. This creates a path between the neutral point switches and the switches that are turned ON by PWM drive control. As a result, the current flowing from the battery 10 and the first capacitor 15 to the target switch flows through the path formed by the changeover switch QH, the neutral point switches, and the switches that are controlled ON by PWM drive control. Consequently, the current flowing from the battery 10 and the first capacitor 15 to the target switch can be reduced. The process then proceeds to step S14.

[0064] In step S14, the control device 70 switches the target switch to off control. In this case, since the current flowing through the target switch is reduced when it is switched to off control, the surge voltage generated in the target switch is reduced. As a result, the occurrence of a situation in which the surge voltage exceeds the withstand voltage of the target switch can be suppressed, and the target switch can be protected from short-circuit current and surge voltage.

[0065] The procedure for the control device 70 to protect the target switch will be explained in detail using Figures 6 to 9. Figures 6 to 9 also show an example where the U-phase first upper arm switch SUHa short-circuits in the Y-drive control state shown in Figure 3. Figures 6 to 9 schematically show the first inductor 91 and the second inductor 92 as wiring inductances for busbars, etc.

[0066] Figure 6 shows a state in which the U-phase first upper arm switch SUHa has short-circuited. In this state, when the target switch, the U-phase first lower arm switch SULa, is switched to ON control by PWM drive control, a short-circuit current flows to the system 100 through the series connection of the U-phase of the first inverter 20. Specifically, a short-circuit current flows from the storage battery 10 and the first capacitor 15 to the U-phase first lower arm switch SULa via the high-potential path 11.

[0067] In the state shown in Figure 6, when the control device 70 switches the U-phase first lower arm switch SULa to off control, the short-circuit current flowing from the battery 10 and the first capacitor 15 to the U-phase first lower arm switch SULa via the high-potential path 11 is blocked, and a surge voltage is generated due to the first inductor 91.

[0068] To prevent such large surge voltages from occurring, as shown in Figure 7, the control device 70 switches the changeover switch QH to ON control when it determines that the U-phase first upper arm switch SUHa has short-circuited. As a result, the current that previously flowed only in one direction through the body diode DH in the high-potential path 11 now flows bidirectionally through the changeover switch QH. In this case, the current flowing from the battery 10 and the first capacitor 15 to the high-potential path 11 flows not only through the U-phase first lower arm switch SULa but also to the second capacitor 16 side via the changeover switch QH. As a result, the current flowing from the battery 10 and the first capacitor 15 to the U-phase first lower arm switch SULa can be reduced.

[0069] In this embodiment, a method is employed to further enhance the current reduction effect. This method will be explained using Figure 8. Figure 8 shows, as an example, a state in which the W-phase first lower arm switch SWLa is controlled to ON by PWM drive control. The control device 70 maintains the neutral point switches, the U, V, and W-phase second upper arm switches SUHb to SWHb, in the ON state. This creates a path between the W-phase second upper arm switch SWHb, the W-phase winding 51W, and the W-phase first lower arm switch SWLa. As a result, the current flowing from the battery 10 and the first capacitor 15 to the second capacitor 16 flows through the path between the W-phase second upper arm switch SWHb, the W-phase winding 51W, and the W-phase first lower arm switch SWLa. Consequently, the effect of reducing the current flowing from the battery 10 and the first capacitor 15 to the U-phase first lower arm switch SULa can be enhanced.

[0070] As shown in Figure 9, the control device 70 switches the U-phase first lower arm switch SULa to off control. Since the U-phase first lower arm switch SULa is switched to off control while the collector current flowing through it is reduced, the surge voltage is reduced. As a result, the occurrence of a situation where the surge voltage exceeds the withstand voltage of the U-phase first lower arm switch SULa can be suppressed, and the target switch can be protected from short-circuit current and surge voltage.

[0071] <Modification of the First Embodiment> As shown in Figure 10, the system 100 may include a second changeover switch QL in addition to the first changeover switch QH, which is the changeover switch QH described in the first embodiment. The second changeover switch QL is provided in the low-potential path 12. In this embodiment, the second changeover switch QL is a semiconductor switching element, more specifically, an N-channel MOSFET. In this case, the second changeover switch QL has a body diode DL.

[0072] Specifically, the drain of the second changeover switch QL is connected to the second inverter 30, and the source of the second changeover switch QL is connected to the first inverter 20. When the second changeover switch QL is turned on, it electrically connects the emitters of the first lower arm switches SULa to SWLa in each phase to the emitters of the second lower arm switches SULB to SWLb in each phase. On the other hand, when the second changeover switch QL is turned off, it electrically disconnects the emitters of the first lower arm switches SULa to SWLa in each phase from the emitters of the second lower arm switches SULB to SWLb in each phase.

[0073] When the control device 70 selects H drive control, it turns on the first changeover switch QH and the second changeover switch QL. On the other hand, when the control device 70 selects Y drive control, it turns off the first changeover switch QH and the second changeover switch QL.

[0074] Furthermore, when Y-drive control is selected, the control device 70 may fix the second upper arm switches SUHb to SWHb in the OFF position and the second lower arm switches SULb to SWLb in the ON position, as shown in Figure 11. In this case, the second lower arm switches SULb to SWLb function as neutral point switches.

[0075] In this case, in step S12 of Figure 5, the control device 70 only needs to switch the first and second changeover switches QH and QL to ON control.

[0076] The system 100 may have a second changeover switch QL instead of a first changeover switch QH. In this case, the U, V, and W phase second lower arm switches SULb to SWLb function as neutral point switches. In step S12 of Figure 5, the control device 70 simply needs to switch the second changeover switch QL to ON control.

[0077] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, the control device 70 sets the period PL from the processing in step S12 in Figure 5 to the processing in step S14.

[0078] When the temperature of the target switch is low, the short-circuit withstand capability of the target switch is longer than when the temperature of the target switch is high. Therefore, when the temperature of the target switch is low, the PL (Plane Limit) period until the target switch is switched to off control can be extended compared to when the temperature of the target switch is high.

[0079] Next, Figure 12 illustrates an example of the target switch protection process using a flowchart. In Figure 12, the same steps as those in Figure 5 are given the same step numbers for convenience.

[0080] In step S13, the control device 70 maintains the neutral point switches, the U, V, and W phase second upper arm switches SUHb to SWHb, in the ON position and proceeds to step S20. In step S20, the control device 70 obtains the temperature Tsd of the target switch detected by the state detection sensor 65 and proceeds to step S21.

[0081] In step S21, the control device 70 sets the period PL to be longer when the acquired temperature Tsd of the target switch is low than when the temperature Tsd of the target switch is high. Specifically, the lower the temperature Tsd, the longer the period PL is set. In addition to this setting method, for example, the period PL may be set binaryly according to the temperature Tsd.

[0082] In step S22, the control device 70 waits until it determines that a period PL based on the temperature Tsd of the target switch has elapsed since the processing in step S12. The period PL, which is determined based on the temperature Tsd of the target switch, is set so as not to exceed the short-circuit withstand capability of the target switch.

[0083] If the period PL has elapsed in step S22, the control device 70 proceeds to step S14.

[0084] In step S22, as the standby period PL of the control device 70 lengthens, the current flowing from the battery 10 and the first capacitor 15 to the second inverter 30 via the changeover switch QH increases. As a result, current is sufficiently distributed to the second inverter 30, and the current flowing from the battery 10 and the first capacitor 15 to the target switch is reduced. This reduces the surge voltage caused by the off control of the target switch. As a result, it is possible to reduce the surge voltage generated at the target switch while avoiding failure of the target switch due to short-circuit current.

[0085] <Other Embodiments> Each of the above embodiments may be modified as follows.

[0086] In step S10 of Figures 5 and 12, the control device 70 may determine whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb based on the detected current values ​​of the switches SUHa to SWLb detected by the state detection sensor 65. An example of a method for determining whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb will be described below.

[0087] For example, in step S10, if the control device 70 determines that the detected current flowing through each switch SUHa to SWLb is higher than the current threshold, it determines that a short-circuit current is flowing through the target switch. On the other hand, if the control device 70 determines that the detected current flowing through each switch SUHa to SWLb is less than or equal to the current threshold, it determines that no short-circuit current is flowing through the target switch.

[0088] In step S10 of Figures 5 and 12, the control device 70 may determine whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb based on the detection values ​​of the second and third current sensors 61 and 62 detected by the state detection sensor 65. An example of a method for determining whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb will be described below.

[0089] For example, in step S10, if the control device 70 determines that the sum of the detected values ​​from the second and third current sensors 61 and 62 is higher than the current threshold, it determines that a short-circuit current is flowing through the target switch. On the other hand, if the control device 70 determines that the sum of the detected values ​​from the second and third current sensors 61 and 62 is less than or equal to the current threshold, it determines that no short-circuit current is flowing through the target switch.

[0090] In step S10 of Figures 5 and 12, the control device 70 may determine whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb based on the temperature detection values ​​of each switch SUHa to SWLb detected by the state detection sensor 65. An example of a method for determining whether or not a short-circuit current is flowing through any of the switches SUHa to SWLb will be described below.

[0091] For example, in step S10, if the control device 70 determines that the detected temperature of each switch SUHa to SWLb is higher than the temperature threshold, it determines that a short-circuit current is flowing through the target switch. On the other hand, if the control device 70 determines that the detected temperature of each switch SUHa to SWLb is below the temperature threshold, it determines that no short-circuit current is flowing through the target switch.

[0092] If any of the switches SUHa to SWLb short-circuit, a short-circuit current flows through the affected switch. If the short-circuit current continues to flow, the temperature of the affected switch will rise. Therefore, the control device 70 can determine the short-circuit current based on the detected temperature values ​​of each switch SUHa to SWLb.

[0093] - Of the upper and lower arm switches of either the first or second inverter 20 or 30, the switch on the opposite arm side of the target switch that is switched to off control by the target switch protection process does not need to be short-circuit faulted. Specifically, for example, if the upper arm switch of the upper and lower arm switches is on for some reason, even though it should be in the off state, a short-circuit current will flow when the lower arm switch is subsequently turned on. In other words, the short-circuit abnormality in this disclosure includes, in addition to or instead of a short-circuit fault of a switch, an abnormality in which a switch that should be in the off state is in the on state. The above-mentioned factor is, for example, when noise is included in the drive signal supplied to the gate of the switch, even though it has been commanded to be off control by PWM drive control.

[0094] The carrier signal is not limited to a triangular wave signal; for example, it may be a sawtooth wave signal.

[0095] In each of the above embodiments, the control device 70 may perform PWM driving based on spatial vector modulation instead of PWM driving based on a comparison of the magnitudes of the command value and the carrier signal.

[0096] The DC power source is not limited to batteries; for example, it could be a fuel cell.

[0097] The rotating electric machine is not limited to permanent magnet field type synchronous machines; for example, an induction machine may also be used.

[0098] The rotating electric machine is not limited to three-phase machines; it may also be two-phase or have four or more phases.

[0099] The semiconductor switches constituting the first and second inverters are not limited to IGBTs; for example, N-channel MOSFETs may also be used. 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.

[0100] The changeover switch is not limited to an N-channel MOSFET; for example, it may be an IGBT with freewheeling diodes connected in antiparallel.

[0101] The inverter, rotating electric machine, and control device are not limited to vehicles; they may also be installed on other moving objects such as aircraft or ships. If the moving object is an aircraft, the rotating electric machine will be the aircraft's power source for flight; if the moving object is a ship, the rotating electric machine will be the ship's power source for navigation.

[0102] In this disclosure or claims, the term "processor" means one or more hardware processors configured to execute processing defined by computer program code (i.e., one or more instructions of a computer program) contained in a computer program by reading the computer program code each time. In other words, a "processor" is a hardware device that executes one or more programmed processes. Therefore, computer program code can also be said to be software that can define the processing of the processor according to its content. A "processor" can be a general-purpose or specific-purpose processor, and may be, but is not limited to, a CPU, microprocessor, GPU, and DFP (Data Flow Processor).

[0103] In this disclosure or claims, the term “memory” means one or more hardware memories that are non-transitional tangible recording media configured to record computer program code and / or data in a manner accessible from a processor. “Memory” can be implemented by memory technology such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code that constitutes the program is recorded in memory and executed by a processor, thereby enabling the processor to perform the various functions described above.

[0104] In this disclosure or claims, the term “circuit” refers to one or more logic circuits as hardware, configured to perform specific processing defined by a pre-designed circuit configuration. In other words (and, in contrast to “processor”), “circuit” in this disclosure or claims refers to a hardware device that performs specific processing based on a circuit configuration, rather than processing defined by software such as the computer program code described above. For example, “circuit” may include custom ICs such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) designed with Hardware Description Language (HDL). That is, “circuit” in this disclosure or claims includes all hardware circuits except for the processors described above that perform processing by reading computer program code.

[0105] In this disclosure or claims, the expression "at least one of the circuit and processor" should be interpreted as disjunctive (logical OR) and not as "at least one circuit and at least one processor." Therefore, in this disclosure or claims, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the circuit alone causes the control device to perform all functions. Also, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the processor alone causes the control device to perform all functions. Furthermore, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the circuit causes the control device to perform some functions and the processor causes the control device to perform the remaining functions. In the last example, for example, if the control device performs functions A to C, functions A and B may be implemented by the circuit, and the remaining function C may be implemented by the processor.

[0106] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A rotating electric machine (40) having multiple phase armature windings (51U to 51W), a first inverter (20) having series connections of first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) for the number of phases of the armature winding, a first capacitor (15) connected in parallel to the first inverter, a DC power supply (10) connected in parallel to the first inverter, a second inverter (30) having series connections of second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) for the number of phases of the armature winding, a second capacitor (16) connected in parallel to the second inverter, a high-potential path (11) connecting the high-potential terminal of the first upper arm switch and the high-potential terminal of the second upper arm switch, A system (100) comprising: a low-potential path (12) connecting the low-potential terminal of the first lower arm switch and the low-potential terminal of the second lower arm switch; a changeover switch (QH, QL) provided in at least one of the high-potential path and the low-potential path for electrically connecting or disconnecting the first inverter and the second inverter, wherein the first ends (51Ua to 51Wa) of the armature winding are connected to the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch; and the second ends (51Ub to 51Wb) of the armature winding are connected to the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch; and a control device (70) for a rotating electric machine applied to the system comprising: a setting unit (85) for setting Y drive control or H drive control as the control mode for the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch; The Y drive control comprises: a control unit (86) that controls the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch to turn on and off based on the control mode set by the setting unit; and a determination unit (87) that determines whether there is a short circuit abnormality in the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch, and the Y drive control isControl device for a rotating electric machine, wherein, while the changeover switch is in the OFF state, the second upper arm switch is ON and the second lower arm switch is OFF, or while the changeover switch is in the OFF state, the second lower arm switch is ON and the second upper arm switch is OFF, and the first upper arm switch and the first lower arm switch are turned ON and OFF, the H drive control is a control that turns ON the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch while the changeover switch is in the ON state, the control unit, when the determination unit determines that a short circuit abnormality has occurred in any of the first upper arm switch, the first lower arm switch, the second upper arm switch or the second lower arm switch during the execution of the Y drive control, turns ON the changeover switch and then turns OFF the target switch which is an arm switch among the series connection including the arm switch in which the short circuit abnormality occurred, among the first upper arm switch, the first lower arm switch, the second upper arm switch or the second lower arm switch, that is an arm switch in which the short circuit abnormality has not occurred.

2. The control unit acquires the temperature of the target switch, and if the acquired temperature of the target switch is low, it makes the period from when the changeover switch is turned ON until the target switch is turned OFF longer than when the acquired temperature of the target switch is high, the control device for a rotating electric machine according to claim 1.

3. A control device for a rotating electric machine according to claim 1 or 2, wherein in the Y drive control, the second upper arm switch or the second lower arm switch that is in ON control is used as a neutral point switch, and the control unit maintains the ON control state of the neutral point switch when the determination unit determines that a short circuit abnormality has occurred.

4. A rotating electric machine (40) having multiple phase armature windings (51U to 51W), a first inverter (20) having series connections of first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) for the number of phases of the armature winding, a first capacitor (15) connected in parallel to the first inverter, a DC power supply (10) connected in parallel to the first inverter, a second inverter (30) having series connections of second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) for the number of phases of the armature winding, a second capacitor (16) connected in parallel to the second inverter, a high-potential path (11) connecting the high-potential terminal of the first upper arm switch and the high-potential terminal of the second upper arm switch, A system (100) comprising: a low-potential path (12) connecting the low-potential terminal of the first lower arm switch and the low-potential terminal of the second lower arm switch; a changeover switch (QH, QL) provided in at least one of the high-potential path and the low-potential path for electrically connecting or disconnecting the first inverter and the second inverter, wherein the first ends (51Ua to 51Wa) of the armature winding are connected to the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch; and the second ends (51Ub to 51Wb) of the armature winding are connected to the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch. In a program applied to the system, a setting process is performed to set Y drive control or H drive control as the control mode for the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, in at least one of the circuit and processor (71). Based on the control mode set by the setting process, the Y drive control executes a control process that turns the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch on and off, and a determination process that determines if there is a short circuit abnormality in the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch, and the Y drive control is performed.The program is a control that, while the changeover switch is in the OFF state, turns on the second upper arm switch and turns off the second lower arm switch, or while the changeover switch is in the OFF state, turns on the second lower arm switch and turns off the second upper arm switch, and also turns on and off the first upper arm switch and the first lower arm switch, the H drive control is a control that, while the changeover switch is in the ON state, turns on and off the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, the control process is a process that, while the execution of the Y drive control, the determination process determines that a short circuit abnormality has occurred in any of the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, then turns on the changeover switch, and then turns off the target switch which is an arm switch among the series connection including the arm switch in which the short circuit abnormality occurred, among the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, and which is an arm switch in which the short circuit abnormality has not occurred, the Y drive control is performed.

5. A rotating electric machine (40) having multiple phase armature windings (51U to 51W), a first inverter (20) having series connections of first upper arm switches (SUHa to SWHa) and first lower arm switches (SULa to SWLa) for the number of phases of the armature winding, a first capacitor (15) connected in parallel to the first inverter, a DC power supply (10) connected in parallel to the first inverter, a second inverter (30) having series connections of second upper arm switches (SUHb to SWHb) and second lower arm switches (SULb to SWLb) for the number of phases of the armature winding, a second capacitor (16) connected in parallel to the second inverter, a high-potential path (11) connecting the high-potential terminal of the first upper arm switch and the high-potential terminal of the second upper arm switch, A system (100) comprising: a low-potential path (12) connecting the low-potential terminal of the first lower arm switch and the low-potential terminal of the second lower arm switch; a changeover switch (QH, QL) provided in at least one of the high-potential path and the low-potential path for electrically connecting or disconnecting the first inverter and the second inverter, wherein the first ends (51Ua to 51Wa) of the armature winding are connected to the low-potential terminal of the first upper arm switch and the high-potential terminal of the first lower arm switch; and the second ends (51Ub to 51Wb) of the armature winding are connected to the low-potential terminal of the second upper arm switch and the high-potential terminal of the second lower arm switch. A control method applied to the system comprising: a setting process for setting Y drive control or H drive control as the control mode for the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch, in at least one of the circuit and processor (71); Based on the control mode set by the setting process, the Y drive control executes a control process that turns the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch on and off, and a determination process that determines if there is a short circuit abnormality in the first upper arm switch, the first lower arm switch, the second upper arm switch, and the second lower arm switch, and the Y drive control is performed.A control method comprising: controlling the second upper arm switch to ON and the second lower arm switch to OFF while the changeover switch is OFF, or controlling the second lower arm switch to ON and the second upper arm switch to OFF while the changeover switch is OFF, and also controlling the first upper arm switch and the first lower arm switch to ON and OFF; the H drive control is controlling the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch to ON and OFF while the changeover switch is ON; and the control process is a process in which, if the determination process determines that a short circuit abnormality has occurred in any of the first upper arm switch, the first lower arm switch, the second upper arm switch and the second lower arm switch during the execution of the Y drive control, the changeover switch is turned ON, and then the target switch is turned OFF among the series connection including the first upper arm switch, the first lower arm switch and the second upper arm switch, which is an arm switch in which a short circuit abnormality has not occurred.

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