Winding switch system, vehicle motor drive system, control device, winding switch method, and computer program

Abstract

In a motor in which a stator of each phase includes a plurality of windings, this winding switch system switches the connection states of the plurality of windings of the motor, the winding switch system comprising: a first relay that is set to on when the connection state of the plurality of windings is a first connection state; a second relay that is set to off when the connection state of the plurality of windings is the first connection state; a first opening unit that sets the first relay to off when the connection state is switched from the first connection state to a second connection state; a first determination unit that determines whether a contact of the first relay, which has been set to off by the first opening unit, is in an open state; and a first connection unit that sets the second relay to on when the contact of the first relay has been determined to be in an open state by the first determination unit.

Description

Winding switching system, vehicle motor drive system, control device, winding switching method, and computer program

[0001] This disclosure relates to a winding switching system, a vehicle motor drive system, a control device, a winding switching method, and a computer program. This application claims priority to Japanese Application No. 2023-005033, filed on January 17, 2023, and incorporates by reference all of the contents of that Japanese application.

[0002] Patent Document 1 discloses a variable characteristic type vehicle motor system that uses multiple relays to change the switching characteristics of multiple windings of the motor. In this vehicle motor system, the multiple relays switch the multiple windings of the motor between series connection and parallel connection.

[0003] JP 2020-188597 A

[0004] A winding switching system according to one aspect of the present disclosure is a winding switching system that switches the connection state of a plurality of windings of a motor in which a stator for each phase includes a plurality of windings, and includes: a first relay that is set to on when the connection state of the plurality of windings is a first connection state; a second relay that is set to off when the connection state of the plurality of windings is the first connection state; a first opening unit that sets the first relay to off when the connection state is switched from the first connection state to a second connection state; a first determination unit that determines whether the contact of the first relay set to off by the first opening unit is in an open state; and a first connection unit that sets the second relay to on when the first determination unit determines that the contact of the first relay is in an open state.

[0005] The present disclosure can be realized not only as a winding switching system having the above-described characteristic configuration, but also as a control device included in the winding switching system, or as a control method for a vehicle motor in which characteristic processing steps in the control device are performed. The present disclosure can be realized as a computer program that causes a computer to function as the control device, or as a semiconductor integrated circuit in which part or all of the control device is implemented.

[0006] FIG. 1 is a diagram showing an example of the configuration of a winding switching system according to a first embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of a control device. FIG. 3 is a circuit diagram showing an example of the configuration of a winding switching device according to the first embodiment. FIG. 4 is a circuit diagram showing an example of the configuration of a current sensor and windings according to the first embodiment. FIG. 5 is a flowchart showing an example of winding switching processing by the control device according to the first embodiment. FIG. 6 is a timing chart showing an example of winding switching processing by the control device according to the first embodiment. FIG. 7 is a circuit diagram showing an example of the configuration of a winding switching device and a measurement unit according to a second embodiment. FIG. 8 is a circuit diagram showing an example of the configuration of a modified example of a winding switching device.

[0007] [Problem to be Solved by the Invention] When switching between a series connection and a parallel connection of multiple windings, the multiple relays used in the vehicle motor system disclosed in Patent Document 1 are switched simultaneously. However, even if multiple relays are switched at the same time, the time until the relay contacts actually make contact and the time until the relay contacts actually open may differ for each relay. As a result, it is possible that multiple relays will be in the ON state simultaneously. In this case, the windings will be short-circuited, and a large induced current will be generated by the rotating rotor. This current may cause the contacts to stick.

[0008] Effect of the Present Disclosure According to the present disclosure, even if the connection states of a plurality of windings are switched by a plurality of relays, it is possible to prevent the relays from being turned on simultaneously.

[0009] <Outline of Embodiments of the Present Disclosure> Below, an outline of embodiments of the present disclosure will be listed and described.

[0010] (1) A winding switching system according to this embodiment is a winding switching system for switching connection states of a plurality of windings of a motor in which a stator for each phase includes a plurality of windings, the winding switching system including: a first relay that is set to ON when the connection state of the plurality of windings is a first connection state; a second relay that is set to OFF when the connection state of the plurality of windings is the first connection state; a first opening unit that sets the first relay to OFF when the connection state is switched from the first connection state to a second connection state; a first determination unit that determines whether a contact of the first relay that has been set to OFF by the first opening unit is in an open state; and a first connection unit that sets the second relay to ON when the first determination unit determines that the contact of the first relay is in the open state. This makes it possible to prevent the relays from being simultaneously ON even when the connection state of the plurality of windings is switched from the first connection state to the second connection state using the plurality of relays.

[0011] (2) In the above (1), the winding switching system may further include a second opening unit that sets the second relay to OFF when switching the connection state from the second connection state to the first connection state, a second determination unit that determines whether a contact of the second relay set to OFF by the second opening unit is in an open state, and a second connection unit that sets the first relay to ON when the second determination unit determines that the contact of the second relay is in the open state. This makes it possible to prevent the relays from being simultaneously ON even when switching the connection states of multiple windings from the second connection state to the first connection state using multiple relays.

[0012] (3) In the above (1) or (2), the first determination unit may determine that the contact of the first relay is in an open state when a current measured by a current sensor that measures a current flowing through a switch including the contact of the first relay is equal to or less than a threshold value. This allows the current sensor to determine whether the relay is in an open state.

[0013] (4) In the above (3), the current sensor may be provided on a power line connecting the first relay and any one of the windings of the motor. This allows the current sensor to be provided in various locations as long as it is provided on the power line connecting the first relay and the motor.

[0014] (5) In the above (3), the current sensor may be provided on a power line connecting the motor to a power supply circuit that supplies power to drive the motor. This allows the current sensor to be provided on the power line connecting the power supply circuit and the motor, and for example, a current sensor provided in the power supply circuit can be used.

[0015] (6) In the above (1), the first determination unit may determine whether the contact of the first relay is in an open state based on a voltage measured by a voltage sensor that measures a voltage across a switch including the contact of the first relay. This allows the voltage sensor that measures the voltage across the switch of the relay to determine whether the relay is in an open state.

[0016] (7) In any one of (1) to (6) above, the winding switching system may be configured such that the plurality of windings include a first winding and a second winding, a first terminal of the first relay is connected to a second terminal of the first winding, a second terminal of the first relay is connected to a first terminal of the second winding, a first terminal of the second relay is connected to the first terminal of the second winding, and a second terminal of the second relay is connected to the first terminal of the first winding. This makes it possible to prevent the relays from being simultaneously turned on even when the winding connection state is switched between a first connection state in which two windings are connected in series and a second connection state in which one winding is connected.

[0017] (8) In the above (7), the winding switching system may further include a third relay that is set to OFF when the connection state of the plurality of windings is the first connection state, a first terminal of the third relay is connected to the second terminal of the first winding, a second terminal of the third relay is connected to the second terminal of the second winding, and the first connection unit sets the third relay to ON when switching the connection state from the first connection state to the second connection state. This makes it possible to prevent the relays from being simultaneously ON even when the connection state of the windings is switched between the first connection state in which two windings are connected in series and the second connection state in which two windings are connected in parallel.

[0018] (9) In any one of (1) to (8) above, the first opening unit may send an instruction to a power supply circuit that supplies power to drive the motor to reduce the power and set the first relay to off. This allows the relay to be set to off while the current flowing through the winding is reduced, thereby reducing the risk of relay contacts fusing and extending the life of the relay.

[0019] (10) In the above (9), the first connection unit may set the second relay on and issue an instruction to the power supply circuit that supplies power to drive the motor to restore the suppressed power to the state before the suppression. This allows the power to drive the motor to be quickly restored to the original state after the winding switching system switches the connection state of the windings.

[0020] (11) In any one of (1) to (8) above, when the first opening unit switches the connection state from the first connection state to the second connection state, the first opening unit may set the first relay to off upon receiving a notification indicating that power for driving the motor has been reduced. This allows the relay to be set to off while the current flowing through the winding is reduced, thereby preventing the risk of relay contacts fusing and extending the life of the relay.

[0021] (12) A vehicle motor drive system according to this embodiment includes an AC motor that drives vehicle wheels, the stator of each phase including multiple windings, a power converter that converts DC power into three-phase AC power that drives the AC motor, and the winding switching system according to any one of (1) to (11) above that switches the connection states of the multiple windings. This makes it possible to prevent multiple relays from being turned on simultaneously, even in a vehicle equipped with a winding switching device that switches the connection states of the windings of the AC motor that drives the vehicle wheels.

[0022] (13) A control device according to this embodiment is a control device for controlling a winding switching device that switches connection states of multiple windings of a motor in which a stator for each phase includes multiple windings, and includes: an opening unit that sets off a first relay that is set on when the connection state of the multiple windings is a first connection state when switching from the first connection state to a second connection state; a determination unit that determines whether a contact of the first relay set off by the first opening unit is in an open state; and a connection unit that sets on a second relay that is set off when the connection state of the multiple windings is the first connection state when the determination unit determines that the contact of the first relay is in the open state. This makes it possible to prevent multiple relays from being simultaneously on even when the connection states of multiple windings are switched by multiple relays.

[0023] (14) A winding switching method according to this embodiment is a winding switching method for switching connection states of a plurality of windings of a motor in which a stator for each phase includes a plurality of windings, the method including the steps of: setting off a first relay that is set on when the connection state of the plurality of windings is a first connection state when switching from the first connection state to a second connection state; determining whether a contact of the first relay that is set off by the first opening unit is in an open state; and setting on a second relay that is set off when the connection state of the plurality of windings is the first connection state when the determination unit determines that the contact of the first relay is in the open state. This makes it possible to prevent the plurality of relays from being in an on state simultaneously, even when the connection states of the plurality of windings are switched using the plurality of relays.

[0024] (15) A computer program according to this embodiment is a computer program used by a winding switching device that switches connection states of multiple windings of a motor in which a stator for each phase includes multiple windings, and causes the computer to execute the following steps when switching from a first connection state to a second connection state: setting off a first relay that is set on when the connection state of the multiple windings is a first connection state, determining whether a contact of the first relay that is set off by the first opening unit is in an open state, and setting on a second relay that is set off when the connection state of the multiple windings is the first connection state when the determination unit determines that the contact of the first relay is in the open state. This makes it possible to prevent multiple relays from being in an on state simultaneously, even when the connection states of multiple windings are switched using multiple relays.

[0025] <Details of Embodiments of the Present Disclosure> Hereinafter, details of embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0026] [1. First Embodiment] [1-1. Winding Switching System] Fig. 1 is a diagram showing an example of the configuration of a winding switching system according to a first embodiment. The winding switching system 10 is mounted on a vehicle propelled by a motor, such as an electric vehicle or a plug-in hybrid vehicle (hereinafter referred to as an "electric vehicle"). The winding switching system 10 includes a motor 20, a power converter 30, a battery 40, a control device 50, and a winding switching device 100.

[0027] The motor 20 is a traction motor that generates propulsion power for the electric vehicle. That is, the motor 20 is connected to the wheels 60 and is a drive motor that drives the wheels 60. The motor 20 is driven by three-phase AC power. For example, the motor 20 is a non-commutator AC motor that does not have a commutator and drives a stator with three-phase AC power to generate a rotating magnetic field, which then rotates the rotor. Examples of non-commutator AC motors include synchronous motors, reluctance motors, and induction motors.

[0028] The battery 40 is a battery that supplies power to drive the motor 20. The battery 40 is a secondary battery, such as a lithium ion battery.

[0029] The power converter 30 is an inverter that converts DC power supplied from the battery 40 into three-phase AC power. The power converter 30 may have a function of converting three-phase AC power output when the motor 20 functions as a generator into DC power and charging the battery 40.

[0030] The power converter 30 includes U-phase, V-phase, and W-phase legs. The U-phase leg includes switches 31u and 32u, the V-phase leg includes switches 31v and 32v, and the W-phase leg includes switches 31w and 32w. The switches 31u, 32u, 31v, 32v, 31w, and 32w perform switching to convert DC power into three-phase AC power. The switches 31u, 32u, 31v, 32v, 31w, and 32w are, for example, insulated gate bipolar transistors (IGBTs) or metal oxide semiconductor field-effect transistors (MOSFETs).

[0031] A power line 35u corresponding to the U phase extends from the U-phase leg, a power line 35v corresponding to the V phase extends from the V-phase leg, and a power line 35w corresponding to the W phase extends from the W-phase leg. In the power converter 30, a current sensor 33u is provided on the power line 35u, a current sensor 33v is provided on the power line 35v, and a current sensor 33w is provided on the power line 35w. The current sensor 33u measures the current value of the U-phase current Iu. The current sensor 33v measures the current value of the V-phase current Iv. The current sensor 33w measures the current value of the W-phase current Iw. The current sensors 33u, 33v, and 33w can measure the current values ​​of the currents Iu, Iv, and Iw flowing through the power lines 35u, 35v, and 35w, including DC and AC components. The current sensors 33u, 33v, and 33w are, for example, DC current sensors (direct current sensors) that use Hall sensors or shunt resistors.

[0032] The winding switching device 100 is disposed between the motor 20 and the power converter 30. The power converter 30 and the winding switching device 100 are connected by power lines 35u, 35v, and 35w, and the winding switching device 100 and the motor 20 are connected by a plurality of power lines 25. The winding switching device 100 switches the connection state of a plurality of windings of the motor 20. The configuration of the winding switching device 100 will be described later. Three-phase AC currents Iu, Iv, and Iw output from the power converter 30 are supplied to the motor 20 via the winding switching device 100.

[0033] The measuring unit 26 measures a physical quantity related to the rotation of the motor 20. An example of a physical quantity related to the rotation of the motor is the current flowing through each winding of the motor 20, but the physical quantity is not limited to current. The measuring unit 26 is provided at a location corresponding to the object to be measured. When measuring the current in the power line connecting the winding switching device 100 and the motor 20, the measuring unit 26 is provided on the power lines 212u, 221u, 212v, 221v, 212w, and 221w between the measuring unit 26 and the motor 20. The current is measured by a DC current sensor that uses, for example, a Hall sensor.

[0034] The control device 50 controls the motor 20. Specifically, the control device 50 controls the power converter 30 and the winding switching device 100 to control the motor 20. A signal line extends from the control device 50 to each of the switches 31u, 32u, 31v, 32v, 31w, and 32w, and the control device 50 controls the on and off of the switches 31u, 32u, 31v, 32v, 31w, and 32w. A signal line extends from the control device 50 to the winding switching device 100, and the control device 50 outputs a switching command signal to the winding switching device 100 to command the switching of the connection state of the windings.

[0035] The control device 50 is connected to a sensor 71 that detects the amount of depression of the brake pedal 70, and receives a detection signal output from the sensor 71. The control device 50 is connected to a sensor 81 that detects the amount of depression of the accelerator pedal 80, and receives a detection signal output from the sensor 81.

[0036] A rotation sensor 201 that detects the rotation speed of the motor 20 and a torque sensor 202 that detects the output torque of the motor 20 are attached to the output shaft of the motor 20. The rotation sensor 201 and the torque sensor 202 are connected to the control device 50. The control device 50 receives a detection signal output from the rotation sensor 201 and a detection signal output from the torque sensor 202.

[0037] The control device 50 is connected to a gear shift indicator 90. The gear shift indicator 90 is an input device through which the driver inputs a gear shift instruction. The gear shift indicator 90 is, for example, a shift lever. In another example, the gear shift indicator 90 is a switch through which the driver instructs the driver to shift up or down. The gear shift indicator 90 outputs a gear shift instruction signal in response to an operation by the driver. The control device 50 receives the gear shift instruction signal output from the gear shift indicator 90.

[0038] 2 is a block diagram showing an example of the hardware configuration of the control device 50. The control device 50 includes a processor 501, a non-volatile memory 502, a volatile memory 503, and an interface (I / F) 504.

[0039] The volatile memory 503 is a semiconductor memory such as a static random access memory (SRAM) or a dynamic random access memory (DRAM). The non-volatile memory 502 is a flash memory, a hard disk, a read-only memory (ROM), or the like. The non-volatile memory 502 stores a control program 510, which is a computer program, and data used to execute the control program 510. The functions of the control device 50 are realized when the processor 501 executes the control program 510. The control program 510 can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM. The processor 501 controls the power converter 30 and the winding switching device 100 using the control program 510.

[0040] The processor 501 is, for example, a CPU (Central Processing Unit). However, the processor 501 is not limited to a CPU. The processor 501 may be a GPU (Graphics Processing Unit). The processor 501 is, for example, a multi-core processor. The processor 501 may be a single-core processor. The processor 501 may be, for example, an ASIC (Application Specific Integrated Circuit) or a programmable logic device such as a gate array or FPGA (Field Programmable Gate Array). In this case, the ASIC or programmable logic device is configured to be able to execute the same processing as the control program 510.

[0041] The I / F 504 is connected to the rotation sensor 201, the torque sensor 202, the sensor 71, the sensor 81, and the gear shift indicator 90. The I / F 504 is, for example, an input / output interface or a communication interface. The I / F 504 receives a detection signal indicating the rotation speed of the motor 20 output from the rotation sensor 201. The I / F 504 receives a detection signal indicating the output torque of the motor 20 output from the torque sensor 202. The I / F 504 receives a detection signal indicating the brake pedal depression amount output from the sensor 71. The I / F 504 receives a detection signal indicating the accelerator pedal depression amount output from the sensor 81. The I / F 504 receives the gear shift indicator signal output from the gear shift indicator 90.

[0042] [1-2. Configuration of the Winding Switching Device] Figure 3 is a circuit diagram showing an example of the configuration of the winding switching device according to the first embodiment. The motor 20 includes a plurality of windings 21u, 22u, 21v, 22v, 21w, and 22w. The windings 21u and 22u correspond to the U phase, the windings 21v and 22v correspond to the V phase, and the windings 21w and 22w correspond to the W phase. However, the number of windings for each phase is not limited to two and may be three or more. The windings 22u, 22v, and 22w are connected at a neutral point 23.

[0043] The winding switching device 100 switches the connection states of the windings 21u, 22u, 21v, 22v, 21w, and 22w for each phase between a first connection state and a second connection state. The winding switching device 100 includes control circuits 103u, 103v, and 103w and switching circuits 104u, 104v, and 104w.

[0044] The switching circuits 104u, 104v, and 104w, under control of the control device 50, switch the connection state of the windings 21u, 22u, 21v, 22v, 21w, and 22w between a state in which two windings are connected in series and a state in which one winding is connected. For example, the state in which two windings are connected in series is a state in which, for the U phase, the first terminal of the winding 21u is connected to the power line 35u, the second terminal is connected to the first terminal of the winding 22u via the relay 112u, and the second terminal of the winding 22u is connected to the neutral point 23. On the other hand, the state in which one winding is connected is a state in which the first terminal of the winding 22u is connected to the power line 35u via the relay 111u, and the second terminal of the winding 22u is connected to the neutral point 23. The same applies to the V phase and the W phase. The state in which two windings are connected in series is an example of a first connection state. The state in which one winding is connected is an example of the second connection state, in which the winding 21u is the first winding and the winding 22u is the second winding.

[0045] The following describes the connection relationship between the winding switching device 100, the power line 35u, and the motor 20 for the U phase. The same applies to the V and W phases, so a description thereof will be omitted.

[0046] The power line 35u is connected to a first terminal of the winding 21u. A power line 212u extends from a second terminal of the winding 21u. A power line 221u extends from a first terminal of the winding 22u.

[0047] The switching circuit 104u includes relays 111u and 112u. The relays 111u and 112u are, for example, mechanical (electromagnetic) relays, but are not limited to this and may also be semiconductor relays. The relay is divided into an input side and an output side. In the case of a mechanical relay, for example, the input side is composed of an electromagnetic coil, and the output side is composed of contacts. In the case of a semiconductor relay, for example, the input side is composed of a light-emitting diode, and the output side is composed of a light-receiving element, MOSFET, and IGBT. When a control signal is input to the input side of the relay, the switch on the output side is set to ON or OFF.

[0048] The power line 35u is drawn into the winding switching device 100. Within the winding switching device 100, the power line 35u branches off at a midpoint and is connected to a first terminal of a relay 111u. A second terminal of the relay 111u is connected to a first terminal of a relay 112u. The power lines 212u and 221u extend from the motor 20 and are drawn into the winding switching device 100. A power line 221u extending from the winding 22u is connected to a connection point between the second terminal of the relay 111u and the first terminal of the relay 112u. A power line 212u extending from the winding 21u is connected to a second terminal of the relay 112u.

[0049] When the relay 111u is in the OFF state and the relay 112u is in the ON state, the windings 21u and 22u are in the first connection state. When the relay 111u is in the ON state and the relay 112u is in the OFF state, the winding 21u is in the second connection state.

[0050] A communication line extending from the control circuit 103u is connected to each of the input sides (electromagnetic coil sides) of the relays 112u and 111u. A communication line 102 extending from the control device 50 is connected to the control circuit 103u. The control device 50 transmits a switching signal SS indicating which connection state of the windings to set via the communication line 102. For example, the switching signal SS indicates a first connection state when it is at a low level, and a second connection state when it is at a high level. Alternatively, the switching signal SS may be data including information indicating which relay to set on or off. Here, the low level is, for example, the potential of the vehicle body, and the high level is, for example, the potential of the power supply supplied to the control device 50.

[0051] The control circuit 103u sets the relays 112u and 111u to on or off by individually applying control signals to the input sides of the relays 112u and 111u. Specifically, when the control circuit 103u receives a switching signal SS from the control device 50 to switch the connection state of the windings 21u and 22u from the first connection state to the second connection state, the control circuit 103u sets the relay 111u to the on state and the relay 112u to the off state. When the control circuit 103u receives a switching signal SS from the control device 50 to switch the connection state of the windings 21u and 22u from the first connection state to the second connection state, the control circuit 103u sets the relay 111u to the off state and the relay 112u to the on state.

[0052] The control circuit 103u is configured, for example, by a plurality of logic circuits (AND circuits, NOT circuits, latch circuits, etc.). In another example, the control circuit 103u is configured by a processor. For example, the control circuit 103u is configured by a one-chip microcomputer. The control circuit 103u may also be configured by a programmable logic device such as an ASIC or FPGA.

[0053] The measurement unit 26 is provided on the power line connecting the winding switching device 100 and the motor 20. The measurement unit 26 includes a phase current sensor and a relay current sensor. The phase current sensor 261u is provided on the power line 221u, and the relay current sensor 262u is provided on the power line 212u. The phase current sensor 261u measures the current flowing through the U phase when the windings 21u and 22u are in the first connection state and the second connection state. Hereinafter, the current measured by the phase current sensor may be referred to as the phase current. A signal or information indicating the value of the current measured by the phase current sensor 261u is sent to the control device 50.

[0054] The relay current sensor 262u measures the current flowing through the power line 212u connected to the second terminal of the relay 112u. When the connection state of the windings 21u, 22u is switched from the first connection state to the second connection state, the relay current sensor 262u measures the current in the power line 212u that the relay 112u, which is set to off, is about to interrupt. Hereinafter, the current measured by the relay current sensor may be referred to as the relay current. A signal or information indicating the value of the current measured by the relay current sensor 262u is sent to the control device 50.

[0055] Similarly, for the V phase, a phase current sensor 261v is provided on the power line 221v, and a relay current sensor 262v is provided on the power line 212v. For the W phase, a phase current sensor 261w is provided on the power line 221w, and a relay current sensor 262w is provided on the power line 212w. Note that if the winding switching system 10 is configured without measuring the relay current, it is not necessary to provide the relay current sensors.

[0056] The measuring unit 26 may be provided in the power line connecting the winding switching device 100 and the motor 20, and may be provided in the winding switching device 100 or in the motor 20.

[0057] [1-3. Functions of the Control Device] Returning to FIG. 1 , the functions of the control device 50 will be described. The control device 50 has the functions of a first opening unit 511, a first determination unit 512, a first connection unit 513, a second opening unit 514, a second determination unit 515, and a second connection unit 516. When the processor 501 executes the control program 510, the functions of the first opening unit 511, the first determination unit 512, the first connection unit 513, the second opening unit 514, the second determination unit 515, and the second connection unit 516 are realized. While only the U phase will be described, the same applies to the V phase and the W phase. Below, an example will be described in which the connection state is switched from the first connection unit state to the second connection state, and then switched from the second connection unit state to the first connection state.

[0058] [1-3-1. First Opening Unit] The first opening unit sets the first relay to off when switching the connection state from the first connection state to the second connection state. The first relay is a relay that is set to on in the first connection state. Here, the first relay is the relay 112u, and the second relay is the relay 111u.

[0059] Since the initial state is the first connection state, the relay 111u is set to OFF and the relay 112u is set to ON. Specifically, the control device 50 transmits a switching signal SS to the control circuit 103u, which indicates that the relay 111u is set to OFF and the relay 112u is set to ON. Upon receiving the switching signal SS, the control circuit 103u sets the relay 111u of the switching circuit 104u to OFF and the relay 112u to ON.

[0060] When switching the connection state of the winding from the first connection state to the second connection state, the first opening unit 511 sets the first relay, ie, the relay 112u, to OFF. Specifically, the control device 50 transmits, for example, a switching signal SS indicating that the relay 112u is to be set to OFF to the control circuit 103u. Upon receiving the switching signal SS, the control circuit 103u sets the relay 112u of the switching circuit 104u to OFF.

[0061] [1-3-2. First Determination Unit] The first determination unit determines whether or not the contact of the first relay that has been set to OFF by the first opening unit is in an open state.

[0062] [Current Interruption by Relay] A mechanical relay consists of an electromagnet and a switch. If the relay is an A-contact relay, the relay is set to OFF when the current flowing through the relay's electromagnet is stopped. A-contact relays are also called normally-off relays. When the current is stopped, the electromagnet, which had been acting as a magnet, loses its magnetic function, and the movable contact of the relay's switch, which was attracted by the electromagnet, is pulled away by the force of an elastic body such as a spring. As the movable contact is pulled away, the first contact on the movable contact and the second contact on the fixed contact of the switch are pulled away. As the first and second contacts are pulled away, they enter an open state, interrupting the current flowing through the switch. Therefore, after the current flowing through the relay's electromagnet is stopped, it takes a mechanical action, for example, approximately 10 ms, for the current flowing through the switch to be interrupted. The time from when the current flowing through the relay's electromagnet is stopped to when the current flowing through the switch is interrupted is sometimes referred to as the relay's reset time.

[0063] Furthermore, due to manufacturing variations and other factors, the reset time of a relay with a mechanical structure varies from relay to relay. Furthermore, to protect the driving element, such as a MOSFET, that drives the relay's electromagnet, a diode may be connected in parallel to the relay's electromagnet. This is because the magnetic energy stored in the electromagnet's coil is circulated by the diode and absorbed as a current circulating through the electromagnet coil and diode. The current circulating through the electromagnet coil and diode gradually decays, but if this current is sufficient to attract the movable contact of the switch, the switch will become electrically conductive. This can sometimes result in an unexpectedly long reset time for the relay.

[0064] Therefore, the first determination unit 512 of the present disclosure determines whether the contact of the first relay set to off by the first opening unit is in an open state. Specifically, for example, the first determination unit 512 determines that the contact of the first relay is in an open state when a current measured by a current sensor that measures a current flowing through a switch including the contact of the first relay is equal to or less than a threshold value.

[0065] [When the current sensor is provided on the power line connecting the relay and the motor winding] Figure 4 is a circuit diagram showing an example of the configuration of the current sensor and the winding according to the first embodiment. In Figure 4, the current sensor that measures the current flowing through the switch including the contact of the first relay is a phase current sensor 261u. Although Figure 4 shows only the U phase, the same applies to the V phase and the W phase. The phase current sensor 261u is inserted in the power line 221u that connects the connection point where the second terminal of the relay 111u and the first terminal of the relay 112u are connected to the first terminal of the winding 22u. The phase current sensor 261u measures the current flowing through the power line 221u.

[0066] First, the current flowing through the switch including the contact of the first relay set to OFF is measured. The relay set to ON in the first connection state is relay 112u. Therefore, relay 112u corresponds to the first relay. On the other hand, the relay set to OFF in the first connection state is relay 111u. Therefore, relay 111u corresponds to the second relay. When switching from the first connection state to the second connection state, the first opening unit 511 changes relay 112u, which is the first relay, from ON to OFF. Meanwhile, during the period when relay 112u is changed from ON to OFF, relay 111u is not set to ON. As a result, the phase current sensor 261u measures only the current flowing through the path of winding 21u, relay 112u, and winding 22u. Therefore, the phase current sensor 261u can measure the current flowing through the switch including the contact of relay 112u.

[0067] [When the current sensor is provided on the power line connecting the power supply circuit and the motor] In the above, the phase current sensor 261u has been described as an example of a current sensor that measures the current flowing through a switch including the contacts of the first relay, but this is not limited to a phase current sensor. The current sensor may also be provided on the power line connecting the power supply circuit and the motor. In FIG. 1 , the power converter 30 corresponds to the power supply circuit. The current sensor 33u corresponds to the current sensor that measures the current flowing through the first relay. The current sensor 33u is provided on the power line 35u that connects the power converter 30 and the motor 20. The current sensor may be provided in the power converter 30 or in the winding switching device 100.

[0068] Even in this case, the relay 112u corresponds to the first relay, and the relay 111u corresponds to the second relay. When switching from the first connection state to the second connection state, the first opening unit 511 switches the first relay, the relay 112u, from on to off. Meanwhile, during the period when the relay 112u is switched from on to off, the relay 111u is not switched on. As a result, the current sensor 33u measures the current flowing through the power line 35u, and therefore only measures the current flowing through the path of the winding 21u, the relay 112u, and the winding 21u. Therefore, the current sensor 33u can measure the current flowing through the switch of the relay 112u.

[0069] [Determination Method] The first determination unit 512 determines that the contact of the first relay is in an open state when the current measured by the current sensor is equal to or less than a threshold value.

[0070] Specifically, when the current measured by the phase current sensor 261u or the current sensor 33u is equal to or less than a threshold value, it is determined that the contact of the first relay 112u is in an open state. The threshold value may be set to a value close to zero, or may be set to a value lower than the normal current taking noise and other factors into consideration.

[0071] [1-3-3. First Connection Unit] The first connection unit sets the second relay to ON when the first determination unit determines that the contact of the first relay is in an open state.

[0072] In this example, the first relay is the relay 112u, and the second relay is the relay 111u. Therefore, when the first determination unit 512 determines that the contact of the relay 112u is in an open state, the first connection unit 513 sets the relay 111u to ON. Specifically, for example, the first connection unit 513 transmits a switching signal SS, which indicates that the relay 111u should be set to ON, to the control circuit 103u. Upon receiving the switching signal SS, the control circuit 103u sets the relay 111u to ON. As a result, the connection state of the windings 21u and 22u is set to the second connection state.

[0073] In the above example, the first opening unit 511, the first determination unit 512, and the first connection unit 513 are provided in the control device 50. However, the first opening unit 511, the first determination unit 512, and the first connection unit 513 may be provided in the control circuit 103u. In this case, the control circuit 103u is configured, for example, by a one-chip microcomputer. Such a one-chip microcomputer includes, for example, a processor, a nonvolatile memory, a volatile memory, etc. A control program is stored in the nonvolatile memory. The processor of the one-chip microcomputer executes the control program to realize the functions of the first opening unit 511, the first determination unit 512, and the first connection unit 513. The phase current sensor 261u may send a signal indicating the measured current value or data including information to the control circuit 103u.

[0074] Furthermore, the first opening unit 511 may send an instruction to reduce power to the power supply circuit that supplies power to drive the motor, and set the first relay to off. For example, when the first opening unit 511 sends an instruction to reduce power, the control device 50, upon receiving the instruction to reduce power, controls the power converter 30 to turn off or reduce the power that drives the motor 20. By setting the relay to off when the current flowing through the winding is low, the risk of the relay contacts fusing can be reduced and the life of the relay can be extended.

[0075] The first connection unit may also set the second relay on and issue an instruction to the power supply circuit that supplies power to drive the motor to restore the suppressed power to its pre-restriction state. For example, upon receiving the instruction to restore the suppressed power to its pre-restriction state, the control device 50 controls the power converter 30 to restore the current driving the motor 20 to its pre-restriction state. After the winding switching system switches the winding connection state, the motor 20 can quickly return to its original state.

[0076] Furthermore, when switching the connection state from the first connection state to the second connection state, the first opening unit may set the first relay off upon receiving a notification indicating that the power driving the motor has been reduced. For example, the control device 50 first controls the power converter 30 to turn off or reduce the power driving the motor 20. The control device 50 then sends a notification indicating that the power driving the motor has been reduced to the first opening unit 511. Upon receiving the notification indicating that the power has been reduced, the first opening unit 511 sets the first relay off. This allows the relay to be set off when the current flowing through the winding is low, preventing the risk of the relay contacts fusing and extending the life of the relay.

[0077] [1-3-4. Second Opening Unit] The second opening unit sets the second relay to OFF when switching the connection state from the second connection state to the first connection state.

[0078] In this example, the first relay is the relay 112u, and the second relay is the relay 111u. Therefore, when switching the connection state from the second connection state to the first connection state, the second opening unit 514 sets the second relay, the relay 111u, to OFF. Specifically, the control device 50 transmits, for example, a switching signal SS indicating that the relay 111u is to be set to OFF to the control circuit 103u. Upon receiving this switching signal SS, the control circuit 103u sets the relay 111u of the switching circuit 104u to OFF.

[0079] [1-3-5. Second Determination Unit] The second determination unit determines whether the contact of the second relay set to off by the second opening unit is in an open state. Specifically, for example, the second determination unit 515 determines that the contact of the second relay is in an open state when the current measured by a current sensor that measures the current flowing through a switch including the contact of the second relay is equal to or less than a threshold value.

[0080] First, the current flowing through the switch including the contact of the second relay set to OFF is measured. Since the second relay is the relay 111u, the second determination unit 515 determines that the contact of the relay 111u, which is the second relay, is in an open state when the current measured by the current sensor that measures the current flowing through the switch of the relay 111u is equal to or less than a threshold value.

[0081] When switching from the second connection state to the first connection state, the second opening unit 514 switches the second relay, relay 111u, from on to off. Meanwhile, while relay 111u is being switched from on to off, relay 112u, the first relay, has not yet been switched on. As a result, the phase current sensor 261u measures only the current flowing through the path of relay 111u and winding 22u. Therefore, the phase current sensor 261u can measure the current flowing through the switch of relay 112u. The same applies when a current sensor is provided on the power line connecting the power supply circuit and the motor. However, the second determination unit 515 determines whether the contacts of the second relay are open based on the current measured by the current sensor 33u.

[0082] Therefore, whether the connection state of the windings is switched from the first connection state to the second connection state or from the second connection state to the first connection state, the phase current sensor 261u can measure the current flowing through the switches of the relays 111u and 112u. For this reason, the first determination unit and the second determination unit can share a current sensor, but this is not limited to this, and a current sensor may be provided in each of the first relay and the second relay.

[0083] [1-3-6. Second Connection Unit] The second connection unit sets the first relay on when the second determination unit determines that the contacts of the second relay are in an open state. In this example, the first relay is relay 112u, so when the second determination unit 515 determines that the contacts of relay 111u are in an open state, the second connection unit 516 sets relay 112u on. More specifically, the second connection unit 516 transmits a switching signal SS to the control circuit 103u, indicating that relay 112u should be set on. Upon receiving this switching signal SS, the control circuit 103u sets relay 112u on. This sets the connection state of windings 21u and 22u to the first connection state.

[0084] [1-4. Operation of the Winding Switching System] Next, a description will be given of the operation of the winding switching system 10. The control device 50 executes the winding switching process by the processor 501 executing the control program 510.

[0085] Fig. 5 is a flowchart showing an example of winding switching processing by the control device according to the first embodiment. Fig. 6 is a timing chart showing an example of winding switching processing by the control device according to the first embodiment. An example in which the control device 50 switches the connection state of the windings from the first connection state to the second connection state, and then switches from the second connection state to the first connection state will be described below.

[0086] [Step S101] In this example, since the initial state is the first connection state, the control device 50 transmits a switching signal SS to the control circuit 103u indicating that the relay 111u should be set to OFF and the relay 112u should be set to ON (step S101), and the process proceeds to step S102. Upon receiving this switching signal SS, the control circuit 103u sets the relay 111u to OFF and the relay 112u to ON. This state corresponds to State 1 in the timing chart shown in FIG.

[0087] [Step S102] When switching the connection state from the first connection state to the second connection state, the first opening unit 511 sets the first relay to off (step S102). In this example, the first relay is the relay 112u. The first opening unit 511 sets the relay 112u, which is the first relay that is set to on, to off. After setting the relay 112u to off, the control device 50 proceeds to step S102. This state is the position at which the transition from State 1 to State 2 occurs in the timing chart shown in FIG. 6 .

[0088] [Step S103] The first determination unit determines whether the contact of the first relay that has been set to OFF by the first opening unit is in an open state (step S103).

[0089] First, the current flowing through the contacts of the first relay, which is set to OFF, is measured. The first relay is the relay 112u. The phase current sensor 261u or the current sensor 33u measures the current flowing through the relay 112u.

[0090] If the current measured by the phase current sensor 261u or the current sensor 33u is equal to or less than the threshold, the first determination unit 512 determines that the contact of the relay 112u is open (YES in step S103) and proceeds to step S104. On the other hand, if the current measured by the phase current sensor 261u or the current sensor 33u is equal to or greater than the threshold, the first determination unit 512 determines that the contact of the relay 112u is not open (NO in step S103). The process returns to step S103, where the current is measured again by the phase current sensor 261u or the current sensor 33u, and the first determination unit 512 determines whether the measured current is equal to or less than the threshold. This state corresponds to State 2 in the timing chart shown in FIG. 6.

[0091] [Step S104] When the first determination unit determines that the contact of the first relay is in an open state, the first connection unit sets the second relay to ON (step S104).

[0092] When the first determination unit 512 determines that the contact of the relay 112u is in the open state (YES in step S103), the first connection unit 513 transmits a switching signal SS to the control circuit 103u, indicating that the second relay, the relay 111u, is to be set to ON. Upon receiving this switching signal SS, the control circuit 103u sets the relay 111u to ON. This sets the connection state of the windings 21u and 22u to the second connection state. This state corresponds to the transition from State 2 to State 3 in the timing chart shown in FIG. 6 . To subsequently switch the connection state from the second connection state to the first connection state, proceed to step S105.

[0093] [Step S105] When switching the connection state from the second connection state to the first connection state, the second opening unit 514 sets the second relay to OFF (step S105). In this example, the second relay is the relay 111u. The second opening unit 514 sets the relay 111u, which is set to ON, to OFF. After setting the relay 111u to OFF, the control device 50 proceeds to step S106. This state is the position at which the transition from State 3 to State 4 occurs in the timing chart shown in FIG. 6 .

[0094] [Step S106] The second determination unit determines whether the contact of the second relay that has been set to OFF by the second opening unit is in an open state (step S106).

[0095] First, the second determination unit 515 measures the current flowing through the contact of the second relay that has been set to OFF. The second relay is the relay 111u. The current flowing through the relay 111u is measured by the phase current sensor 261u or the current sensor 33u.

[0096] If the current measured by the phase current sensor 261u or the current sensor 33u is equal to or less than the threshold, the second determination unit 515 determines that the contact of the relay 111u is open (YES in step S106), and the process proceeds to step S107. On the other hand, if the current measured by the phase current sensor 261u or the current sensor 33u is equal to or greater than the threshold, the second determination unit 515 determines that the contact of the relay 111u is not open (NO in step S106), and the process returns to step S106. The current is measured again by the phase current sensor 261u or the current sensor 33u, and the second determination unit 515 determines whether the measured current is equal to or less than the threshold. This state corresponds to State 4 in the timing chart shown in FIG. 6.

[0097] [Step S107] When the second determination unit determines that the contact of the second relay is in the open state, the second connection unit sets the first relay to ON (step S107).

[0098] When the second determination unit 515 determines that the contact of the relay 111u is in the open state (YES in step S106), the second connection unit 516 transmits a switching signal SS to the control circuit 103u, indicating that the relay 112u should be set to ON. The control circuit 103u receives the switching signal SS and sets the relay 112u to ON. This sets the connection state of the windings 21u and 22u to the first connection state. This state corresponds to the transition from State 4 to State 5 in the timing chart shown in FIG. 6. After the relay 112u is set to ON, the winding switching process ends.

[0099] As described above, whether the winding connection state is switched from the first connection state to the second connection state or from the second connection state to the second connection state, the contacts of the relays 111u and 112u are in an open state before the winding connection state is switched. This prevents the windings from becoming short-circuited even when multiple relays are used, and reduces the risk of large induced currents, torque fluctuations, and contact sticking due to large currents. For these reasons, the present disclosure is preferably applied to mechanical relays.

[0100] For convenience of explanation, the U, V, and W phases have been described as being treated independently, but the winding connection state may be changed simultaneously for all phases. In this case, if the relay contacts are determined to be open when the values ​​of the current sensors for the U, V, and W phases all reach zero, and the connection state is switched, inconsistencies among the phases can be avoided. Furthermore, by using a relay that simultaneously opens and closes multiple circuits with a single coil, the circuits for all phases can be opened and closed simultaneously. This allows all phases to be operated uniformly by controlling a single relay, simplifying the circuit and facilitating control.

[0101] [2. Second Embodiment] A winding switching device according to a second embodiment includes a voltage sensor that measures the voltage across the switch including the setting of the first relay, and a determination unit determines whether the output switch is in an electrically open state based on the measured voltage.

[0102] [2-1. Configuration of the Winding Switching Device] Figure 7 is a circuit diagram showing an example of the configuration of the winding switching device and the measurement unit in the second embodiment. The second embodiment differs from the first embodiment in the configuration of the measurement unit 26, but the other configurations are the same. Explanation of the configurations that are the same as those in the first embodiment will be omitted, and only the different parts will be explained, with the same reference numerals used for the same configurations.

[0103] [Measurement Unit] Measurement unit 26 includes voltage sensors 271u, 272u, 271v, 272v, 271w, and 272w. Voltage sensor 271u is connected between U-phase power line 35u and power line 221u, and voltage sensor 271u measures the voltage across the switch of relay 111u. Voltage sensor 272u is connected between U-phase power line 221u and power line 212u, and voltage sensor 272u measures the voltage across the switch of relay 112u. The voltage sensors send information or signals indicating the measured voltages to control device 50. The same applies to the V-phase and W-phase.

[0104] [2-2. Functions of the Control Device] The second embodiment is different from the first embodiment in the functions of the first determination unit 512 and the second determination unit 515, but other functions are the same. Furthermore, the first determination unit 512 and the second determination unit 515 measure different relays, but have the same functions.

[0105] [First Determination Unit, Second Determination Unit] The first determination unit determines whether or not the contact of the first relay is in an open state based on a voltage measured by a voltage sensor that measures the voltage of the first relay.

[0106] First, the first determination unit 512 measures the voltage across the output switch of the first relay, which is set to OFF. When the connection state of the winding is switched from the first connection state to the second connection state, the relay that is set to ON in the first connection state, which is the first connection state, is the relay 112u, and the relay 112u corresponds to the first relay. Therefore, the voltage sensor 272u measures the voltage across the switch of the relay 112u.

[0107] On the other hand, when the connection state of the winding is switched from the second connection state to the first connection state, the second determination unit 515 determines whether the contacts of the relay 111u, which is the second relay, are in an open state based on the voltage across both ends of the switch of the relay 111u, which is the second relay, measured by the voltage sensor 271u.

[0108] The first determination unit 512 and the second determination unit 515 determine that the contacts of the relay are in an open state, for example, when the voltage measured by the voltage sensor is equal to or greater than a threshold value. When the contacts of the relay are in a closed state, the voltage across the switch including the contacts is zero. On the other hand, when the contacts of the relay switch are separated and in an open state, the voltage across the switch is a value completely different from zero.

[0109] That is, when the contacts of the relay switch are opened, one end of the stator windings 21u and 22u is opened. At this time, the rotor of the motor 20 is rotating, and some voltage is generated in the stator windings 21u and 22u, which is a value completely different from zero. The voltage sensors 271u and 272u measure this voltage, and if the voltage is equal to or greater than a threshold, it is determined that the output switch of the relay is electrically open. [1-4. Operation of the Winding Switching System] The second embodiment differs from the first embodiment in the operations of steps S103 and S106, but the other operations are the same. In steps S103 and S106, the relays measured are different, but the operations are the same.

[0110] [Step S103] The first determination unit determines whether the contact of the first relay that has been set to OFF by the first opening unit is in an open state (step S103).

[0111] The first determination unit 512 measures the voltage across the switch of the first relay that is set to OFF. The first relay is the relay 112u. The voltage sensor 272u measures the voltage across the switch of the relay 112u.

[0112] If the voltage measured by the voltage sensor 272u is equal to or greater than the threshold, it is determined that the switch contact is in the open state (YES in step S103), and the process proceeds to step S103. On the other hand, if the voltage measured by the voltage sensor 272u is equal to or less than the threshold, it is determined that the switch contact is not in the open state (NO in step S103), and the process returns to step S103, where the first determination unit 512 again determines whether the voltage measured by the voltage sensor 272u is equal to or greater than the predetermined threshold.

[0113] As described above, the voltage sensor can also be used to determine whether the relay contacts are open. Therefore, in the second embodiment, the winding connection state is switched after the switch contacts of the relays 111u and 112u have both been in the open state. This prevents the windings from being short-circuited even when multiple relays are used, and reduces the risk of large induced currents, torque fluctuations, and contact sticking due to large currents.

[0114] 3. Third Embodiment A vehicle motor drive system according to a third embodiment includes an AC motor in which a stator for each phase includes multiple windings and drives the wheels of a vehicle, a power converter that converts DC power into three-phase AC power that drives the AC motor, and a winding switching system that switches the connection state of the multiple windings.

[0115] The AC motor that drives the wheels of the vehicle is the traction motor 20 that generates the propulsion force of the electric vehicle. In other words, the motor 20 is connected to the wheels 60 and is a drive motor that drives the wheels 60. The motor 20 is driven by three-phase AC power. The stator of each phase of the motor 20 includes multiple windings. The characteristics of the motor 20 can be changed by switching between the multiple windings.

[0116] The power converter 30 is an inverter that converts DC power supplied from the battery 40 into three-phase AC power. The power converter 30 includes a leg for each phase. Each phase leg includes a switch. The switches perform switching to convert the DC power into three-phase AC power.

[0117] The winding switching system 10 is a winding switching system that switches the connection state of multiple windings of a motor whose stator for each phase includes multiple windings. The winding switching system 10 includes a first relay, a second relay, a first opening unit, a first determination unit, and a first connection unit. The first relay is set to on when the connection state of the multiple windings is a first connection state. The second relay is set to off when the connection state of the multiple windings is the first connection state. The first opening unit sets the first relay to off when switching the connection state from the first connection state to the second connection state. The first determination unit determines whether the contact of the first relay set to off by the first opening unit is in an open state. The first connection unit sets the second relay to on when the first determination unit determines that the contact of the first relay is in an open state.

[0118] As described in the first embodiment, the winding switching system 10 has such a configuration. When switching the connection state of the windings, all relays that switch the connection state of the windings are set to OFF before the connection state is switched. This prevents the windings from being short-circuited even when multiple relays are used, thereby reducing the risk of large induced currents, torque fluctuations, and contact sticking due to large currents. Even in a vehicle equipped with this winding switching system 10, it is possible to prevent multiple relays from being turned ON simultaneously.

[0119] [4. Modification] The winding switching system may further include a third relay that is set to OFF when the connection state of the plurality of windings is the first connection state. A first terminal of the third relay is connected to the second terminal of the first winding, a second terminal of the third relay is connected to the second terminal of the second winding, and the first connection unit sets the third relay to ON when switching the connection state from the first connection state to the second connection state. In FIG. 8 , the third relay is relay 113u. Furthermore, connection states focusing on the second windings include a first connection state in which the first windings are connected in series and a second connection state in which the first windings are not connected in series, and in the second connection state, the first windings may be connected in parallel.

[0120] FIG. 8 is a circuit diagram showing an example of the configuration of a modified example of the winding switching device 100. While FIG. 8 shows only the U phase, the V and W phases are similar. Compared to the first embodiment, a relay 113u has been added. The relay 113u is set to on or off at the same timing as the relay 111u. The addition of the relay 113u allows the windings 21u and 22u to be connected in parallel. Hereinafter, the parallel connection state may be referred to as the second connection state. When connected in parallel, the relays 111u and 113u are set to on, and the relay 112u is set to off. On the other hand, when connected in series, which is the first connection state, the relays 111u and 113u are set to off, and the relay 112u is set to on.

[0121] The winding switching device 100 switches the connection state of the windings of the motor 20 from a first connection state to a second connection state, or from the second connection state to the first connection state. Even in this case, when the connection state of the windings is switched between the first connection state and the second connection state, all of the relays that switch the connection state of the windings are set to on or off after being set to off. This prevents the windings from being short-circuited even when multiple relays are used, and reduces the risk of large induced currents, torque fluctuations, and contact sticking due to large currents.

[0122] [5. Supplementary Notes] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims rather than the above-described embodiments, and includes meanings equivalent to the claims and all modifications within the scope of the claims. Furthermore, while the present invention has been described using a vehicle motor as an example, it is not limited to vehicle motors, and can be applied to AC motors that change characteristics by switching multiple windings using multiple relays.

[0123] 10 Winding switching system 20 Motor (drive motor) 21u, 22u, 21v, 22v, 21w, 22w Winding 23 Neutral point 25 Power line 26 Measurement unit 30 Power converter 31u, 32u, 31v, 32v, 31w, 32w Switch 33u, 33v, 33w Current sensor 35u, 35v, 35w Power line 40 Battery 50 Control device 501 Processor 502 Non-volatile memory 503 Volatile memory 504 Interface (I / F) 510 Control program 511 First opening unit 512 First determination unit 513 First connection unit 514 Second opening unit 515 Second determination unit 516 Second connection unit 60 Wheel 70 Brake pedal 71 Sensor 80 Accelerator pedal 81 Sensor 90 Speed ​​change indicator 100 Winding switching device 102 Communication line (switching signal SS) 102d Delay switching signal SS 103u, 103v, 103w Control circuit 104u, 104v, 104w Switching circuit 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w Relay 201 Rotation sensor 202 Torque sensor 212u, 221u, 212v, 221v, 212w, 221w Power line 261u, 261v, 261w Phase current sensor 262u, 262v, 262w Relay current sensor 271u, 272u, 271v, 272v, 271w, 272w Voltage sensor

Claims

1. A winding switching system for switching connection states of a plurality of windings of a motor in which a stator for each phase includes a plurality of windings, a first relay that is set to ON when the connection state of the plurality of windings is a first connection state; a second relay that is set to an OFF state when the connection state of the plurality of windings is the first connection state; a first opening unit that sets the first relay to off when the connection state is switched from the first connection state to a second connection state; a first determination unit that determines whether or not a contact of the first relay that has been set to OFF by the first opening unit is in an open state; a first connection unit that sets the second relay to ON when the first determination unit determines that the contact of the first relay is in an open state; Equipped with Winding switching system.

2. a second opening unit that sets the second relay to an off state when the connection state is switched from the second connection state to the first connection state; a second determination unit that determines whether or not a contact of the second relay that has been set to OFF by the second opening unit is in an open state; a second connection unit that sets the first relay to ON when the second determination unit determines that the contact of the second relay is in an open state; Further comprising: The winding switching system according to claim 1 .

3. 2. The winding switching system according to claim 1, wherein the first determination unit determines that the contact of the first relay is in an open state when a current measured by a current sensor that measures a current flowing through a switch including the contact of the first relay is equal to or less than a threshold value.

4. The winding switching system according to claim 3 , wherein the current sensor is provided on a power line connecting the first relay and any one of the windings of the motor.

5. 4. The winding switching system according to claim 3, wherein the current sensor is provided on a power line connecting the motor to a power supply circuit that supplies power for driving the motor.

6. 2. The winding switching system according to claim 1, wherein the first determination unit determines whether the contact of the first relay is in an open state based on a voltage measured by a voltage sensor that measures a voltage across both ends of a switch including the contact of the first relay.

7. the plurality of windings include a first winding and a second winding; a first terminal of the first relay connected to a second terminal of the first winding; a second terminal of the first relay connected to a first terminal of the second winding; a first terminal of the second relay connected to the first terminal of the second winding; a second terminal of the second relay connected to a first terminal of the first winding; The winding switching system according to claim 1 .

8. the winding switching system further includes a third relay that is set to an OFF state when the connection state of the plurality of windings is the first connection state; a first terminal of the third relay connected to the second terminal of the first winding; a second terminal of the third relay connected to a second terminal of the second winding; the first connection unit sets the third relay to ON when switching the connection state from the first connection state to the second connection state; The winding switching system according to claim 7.

9. The first opening portion is sending an instruction to reduce the power to a power supply circuit that supplies power to drive the motor, and setting the first relay to an off state; The winding switching system according to claim 1 .

10. The first connection portion is setting the second relay to ON, and instructing the power supply circuit that supplies power to drive the motor to restore the reduced power to the state before the reduction; The winding switching system according to claim 9.

11. The first opening portion is When switching the connection state from the first connection state to the second connection state, setting the first relay to OFF when a notification is received indicating that power to drive the motor has been reduced; The winding switching system according to any one of claims 1 to 8.

12. an AC motor having a stator for each phase including a plurality of windings for driving wheels of a vehicle; a power converter that converts DC power into three-phase AC power for driving the AC motor; a winding switching system according to claim 1 that switches connection states of the plurality of windings; Equipped with Vehicle motor drive system.

13. A control device for controlling a winding switching device of a motor in which a stator for each phase includes a plurality of windings and switches connection states of the plurality of windings, an opening unit that sets the first relay, which is set to ON when the connection state of the plurality of windings is a first connection state, to OFF when switching from the first connection state to a second connection state; a determination unit that determines whether or not a contact of the first relay that has been set to OFF by the first opening unit is in an open state; a connection unit that sets a second relay, which is set to OFF when the connection state of the plurality of windings is the first connection state, to ON when the determination unit determines that the contact of the first relay is in an open state; Equipped with Control device.

14. A winding switching method for switching connection states of a plurality of windings of a motor in which a stator for each phase includes a plurality of windings, comprising: a step of setting a first relay, which is set to ON when the connection state of the plurality of windings is in a first connection state, to OFF when switching from the first connection state to a second connection state; a step of determining whether or not a contact of the first relay set to OFF in the setting to OFF step is in an open state; a step of setting a second relay, which is set to OFF when the connection state of the plurality of windings is the first connection state in the determining step, to ON when it is determined that the contact of the first relay is in an open state; Including, Winding switching method.

15. A computer program used by a winding switching device for switching connection states of a plurality of windings of a motor in which a stator of each phase includes a plurality of windings, the computer program comprising: On the computer, a step of setting a first relay, which is set to ON when the connection state of the plurality of windings is in a first connection state, to OFF when switching from the first connection state to a second connection state; a step of determining whether or not a contact of the first relay set to OFF in the setting to OFF step is in an open state; a step of setting a second relay, which is set to OFF when the connection state of the plurality of windings is the first connection state in the determining step, to ON when it is determined that the contact of the first relay is in an open state; In order to execute Computer program.