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

Abstract

The winding switching system switches the connection state of a plurality of windings in a motor in which each phase stator includes the plurality of windings. The winding switching system includes: a first relay that is provided to be turned on when the connection state of the plurality of windings is a first connection state, and a second relay that is provided to be turned on when the connection state of the plurality of windings is a second connection state; a second relay provided to be disconnected when the connection state of the plurality of windings is the first connection state; a first opening unit that turns off the first relay 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, which has been set to be open by the first opening unit, is in an open state; and a first connection unit that turns on the second relay when the first determination unit determines that the contact of the first relay is in the open state.

Description

Technical Field

[0001] The present 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 based on Japanese application No. 2023-005033, filed on January 17, 2023, and incorporates the entire contents of that Japanese application by reference. Background Art

[0002] Patent Document 1 discloses a variable characteristic vehicle motor system that uses multiple relays to switch multiple windings to change characteristics. This vehicle motor system uses multiple relays to switch multiple windings of a motor between series connection and parallel connection. Prior art literature Patent Literature

[0003] Patent document 1: Japanese Patent Application Laid-Open No. 2020-188597. Summary of the Invention

[0004] One aspect of the present disclosure relates to a winding switching system that switches the connection status of multiple windings of an electric motor whose stator includes multiple windings in each phase. The winding switching system comprises: a first relay that is set to be conductive when the connection status of the multiple windings is a first connection status; a second relay that is set to be disconnected when the connection status of the multiple windings is the first connection status; a first opening portion that sets the first relay to be disconnected when the connection status is switched from the first connection status to the second connection status; a first determination portion that determines whether the contacts of the first relay that have been set to be disconnected by the first opening portion are in an open state; and a first connection portion that sets the second relay to be conductive when the first determination portion determines that the contacts of the first relay are in an open state.

[0005] The present disclosure can be implemented not only as a winding switching system having the characteristic structure described above, but also as a control device included in the winding switching system, or as a method for controlling a vehicle electric motor using the characteristic processing steps of the control device. The present disclosure can also be implemented as a computer program that causes a computer to function as the control device, or as a semiconductor integrated circuit that implements part or all of the control device. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a diagram showing an example of the configuration of the winding switching system according to the first embodiment. Figure 2 This is a block diagram showing an example of the hardware configuration of the control device. Figure 3This is a circuit diagram showing an example of the configuration of the winding switching device according to the first embodiment. Figure 4 This is a circuit diagram showing an example of the configuration of the current sensor and the winding according to the first embodiment. Figure 5 This is a flowchart showing an example of the winding switching process performed by the control device according to the first embodiment. Figure 6 This is a timing chart showing an example of the winding switching process performed by the control device according to the first embodiment. Figure 7 This is a circuit diagram showing an example of the configuration of a winding switching device and a measuring unit in the second embodiment. Figure 8 This is a circuit diagram showing an example of the structure of a modified example of the winding switching device. DETAILED DESCRIPTION

[0007] [Problems to be Solved by the Invention] When switching between series and parallel connection of multiple windings, the multiple relays used in the automotive electric motor system disclosed in Patent Document 1 are switched simultaneously. However, even if the multiple relays are switched at the same time, the time it takes for each relay's contacts to actually make contact and the time it takes for each relay's contacts to actually open can vary from relay to relay. Therefore, consider the situation where multiple relays are turned on simultaneously. In this case, the windings could short-circuit, and the rotating rotor could generate a large induced current, potentially causing contact sticking.

[0008] [Effects of the Present Disclosure] According to the present disclosure, even when a plurality of relays are used to switch the connection states of a plurality of windings, it is possible to prevent the relays from being in the on state at the same time.

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

[0010] (1) The winding switching system according to this embodiment switches the connection state of the plurality of windings of an electric motor having a stator including a plurality of windings for each phase. The winding switching system includes: a first relay that is set to be conductive when the connection state of the plurality of windings is in a first connection state; a second relay that is set to be disconnected when the connection state of the plurality of windings is in the first connection state; a first opening portion that sets the first relay to be disconnected when the connection state is switched from the first connection state to the second connection state; a first determination portion that determines whether the contact of the first relay, which has been disconnected by the first opening portion, is in an open state; and a first connection portion that sets the second relay to be conductive when the first determination portion determines that the contact of the first relay is in an open state. Thus, 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, it is possible to prevent the relays from being in a conductive state at the same time.

[0011] (2) In the above (1), the winding switching system may further include: a second opening portion that sets the second relay to an open state when the connection state is switched from the second connection state to the first connection state; a second determination portion that determines whether the contact of the second relay, which has been set to an open state by the second opening portion, is in an open state; and a second connection portion that sets the first relay to a conductive state when the second determination portion determines that the contact of the second relay is in an open state. Thus, even if the connection state of multiple windings is switched from the second connection state to the first connection state using multiple relays, it is possible to prevent the relays from being in a conductive state at the same time.

[0012] (3) In (1) or (2) above, the first determination unit may determine that the contacts of the first relay are in the open state when the current measured by a current sensor is less than a threshold value, and the current sensor measures the current flowing through a switch including the contacts of the first relay. Thus, whether the relay is in the open state can be determined by the current sensor.

[0013] (4) In the above (3), the current sensor may be provided on a power line connecting the first relay to any winding of the motor. Thus, the current sensor only needs to be provided on the power line connecting the first relay to the motor, and the current sensor can be provided at various locations.

[0014] (5) In the above (3), the current sensor may be provided on a power line connecting a power supply circuit and the motor, wherein the power supply circuit supplies power for driving the motor. Thus, the current sensor only needs to be provided on the power line connecting the power supply circuit and the motor. For example, a current sensor provided within the power supply circuit may be used.

[0015] (6) In the above (1), the first determination unit may determine whether the contacts of the first relay are in the open state based on a voltage measured by a voltage sensor that measures a voltage across a switch including the contacts of the first relay. Thus, it is possible to determine whether the relay is in the open state using the voltage sensor that measures the voltage across the switch of the relay.

[0016] (7) In any one of (1) to (6) above, the plurality of windings may include a first winding and a second winding in the winding switching system, the first terminal of the first relay being connected to the second terminal of the first winding, the second terminal of the first relay being connected to the first terminal of the second winding, the first terminal of the second relay being connected to the first terminal of the second winding, and the second terminal of the second relay being connected to the first terminal of the first winding. Thus, even when the connection state of the windings switches between a first connection state in which two windings are connected in series and a second connection state in which one winding is connected, the relays are prevented from being simultaneously turned on.

[0017] (8) In the above (7), the winding switching system may further include a third relay that is set to be disconnected when the connection state of the plurality of windings is the first connection state, the first terminal of the third relay being connected to the second terminal of the first winding, and the second terminal of the third relay being connected to the second terminal of the second winding, and the first connection portion setting the third relay to be conductive when the connection state is switched from the first connection state to the second connection state. Thus, 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, it is possible to prevent the relays from being simultaneously conductive.

[0018] (9) In any of the above (1) to (8), the first opening portion may notify a power supply circuit that supplies power to drive the motor of an instruction to suppress the power, thereby setting the first relay to be open. Thus, the relay can be set to be open while the current flowing in the winding is suppressed, thereby reducing the possibility of relay contacts welding and extending the life of the relay.

[0019] (10) In the above (9), the first connection unit may turn on the second relay and notify the power supply circuit that supplies the power to drive the motor of an instruction to restore the suppressed power to its pre-suppression state. Thus, after the winding switching system switches the connection state of the windings, the power to drive the motor can be quickly restored to its original state.

[0020] (11) In any of the above (1) to (8), when the connection state is switched from the first connection state to the second connection state, the first opening portion may be configured to open the first relay upon receiving a notification indicating that the power to drive the motor has been suppressed. Thus, the relay can be opened while the current flowing through the winding is suppressed, thereby reducing the possibility of relay contacts welding and extending the life of the relay.

[0021] (12) The vehicle motor drive system according to this embodiment includes: an AC motor for driving vehicle wheels, wherein each phase of the AC motor includes a plurality of windings; a power converter for converting DC power into three-phase AC power for driving the AC motor; and a winding switching system according to any one of (1) to (11) above for switching the connection state of the plurality of windings. Thus, even in a vehicle equipped with a winding switching device for switching the connection state of the windings of the AC motor driving the vehicle wheels, it is possible to prevent a plurality of relays from being in a conducting state at the same time.

[0022] (13) The control device according to this embodiment controls a winding switching device that switches the connection state of a plurality of windings of an electric motor having a stator of each phase including a plurality of windings. The control device includes: an opening unit that, when the connection state is switched from a first connection state to a second connection state, sets a first relay that was set to be on when the connection state of the plurality of windings was in the first connection state to be off; a determination unit that determines whether the contact of the first relay that has been set to be off by the first opening unit is in the open state; and a connection unit that, when the determination unit determines that the contact of the first relay is in the open state, sets the second relay that was set to be off when the connection state of the plurality of windings was in the first connection state to be on. Thus, even if the connection state of the plurality of windings is switched using a plurality of relays, it is possible to prevent the relays from being in the on state at the same time.

[0023] (14) The winding switching method according to this embodiment switches the connection state of the plurality of windings of an electric motor having a stator of each phase including a plurality of windings. The winding switching method includes the following steps: when the connection state is switched from a first connection state to a second connection state, setting the first relay that was set to be conductive when the connection state of the plurality of windings was in the first connection state to be disconnected; determining whether the contact of the first relay that has been set to be disconnected by the first opening unit is in the open state; and when the determination unit determines that the contact of the first relay is in the open state, setting the second relay that was set to be disconnected when the connection state of the plurality of windings was in the first connection state to be conductive. Thus, even if the connection state of the plurality of windings is switched using a plurality of relays, it is possible to prevent the plurality of relays from being in the conductive state at the same time.

[0024] (15) The computer program according to this embodiment is used by a winding switching device that switches the connection state of a plurality of windings of an electric motor having a stator of each phase including a plurality of windings. The computer program causes a computer to execute the following steps: when the connection state is switched from a first connection state to a second connection state, setting a first relay that was set to be on when the connection state of the plurality of windings was in the first connection state to be off; determining whether the contact of the first relay that has been set to be off by the first opening unit is in an open state; and when the determination unit determines that the contact of the first relay is in an open state, setting a second relay that was set to be off when the connection state of the plurality of windings was in the first connection state to be on. Thus, even if a plurality of relays are used to switch the connection state of a plurality of windings, it is possible to prevent the plurality of relays from being in an on state at the same time.

[0025] <Details of the embodiment of the present disclosure> Hereinafter, details of the embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that at least some of the embodiments described below can be combined arbitrarily.

[0026] [1. First embodiment] [1-1. Winding switching system] Figure 1 This figure shows an example of the configuration of a winding switching system according to the first embodiment. Winding switching system 10 is installed in a vehicle propelled by an electric motor, such as an electric vehicle or a plug-in hybrid vehicle (hereinafter referred to as an "electric vehicle"). 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 electric motor 20 is a driving motor that generates propulsion for the electric vehicle. Specifically, the electric motor 20 is connected to the wheels 60 and drives them. The electric motor 20 is driven by three-phase alternating current (AC). For example, the electric motor 20 is a commutatorless AC motor that does not have a commutator. The stator is driven by three-phase AC power to generate a rotating magnetic field, which in turn rotates the rotor. Examples of commutatorless AC motors include synchronous motors, reluctance motors, and induction motors.

[0028] The battery 40 is a battery for supplying electric power for driving the electric motor 20. The battery 40 is a secondary battery, such as a lithium-ion battery.

[0029] Power converter 30 is an inverter that converts DC power supplied from battery 40 into three-phase AC power. Power converter 30 may also have a function of converting three-phase AC power output by motor 20 when it functions as a generator into DC power to charge battery 40.

[0030] Power converter 30 includes arms for the U, V, and W phases. The U-phase arm includes switches 31u and 32u, the V-phase arm includes switches 31v and 32v, and the W-phase arm includes switches 31w and 32w. Switching by switches 31u, 32u, 31v, 32v, 31w, and 32w converts direct current (DC) into three-phase alternating current (AC). Switches 31u, 32u, 31v, 32v, 31w, and 32w are, for example, IGBTs (insulated gate bipolar transistors) or MOSFETs (metal oxide semiconductor field effect transistors).

[0031] A power line 35u corresponding to U extends from the U-phase arm, a power line 35v corresponding to V extends from the V-phase arm, and a power line 35w corresponding to W extends from the W-phase arm. In power converter 30, current sensors 33u, 33v, and 33w are provided on power line 35u, 35v, and 35w, respectively. Current sensor 33u measures the current value of U-phase current Iu, current sensor 33v measures the current value of V-phase current Iv, and current sensor 33w measures the current value of W-phase current Iw. Current sensors 33u, 33v, and 33w can measure the current values ​​of currents Iu, Iv, and Iw flowing through power lines 35u, 35v, and 35w, which include both DC and AC components. Current sensors 33u, 33v, and 33w are, for example, DC circuit sensors (DC current sensors) using 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 via power lines 35u, 35v, and 35w, and the winding switching device 100 and the motor 20 are connected via a plurality of power lines 25. The winding switching device 100 switches the connection state of the multiple windings of the motor 20. The specific structure of the winding switching device 100 will be described later. The 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] Measuring unit 26 measures physical quantities related to the rotation of motor 20. Examples of physical quantities related to motor rotation include, but are not limited to, currents flowing through the windings of motor 20. Measuring unit 26 is located at a position corresponding to the measurement target. When measuring the current in the power lines connecting winding switching device 100 and motor 20, power lines 212u, 221u, 212v, 221v, 212w, and 221w are provided between measuring unit 26 and motor 20. The current is measured using, for example, a DC current sensor utilizing a Hall effect sensor.

[0034] The control device 50 controls the motor 20. Specifically, the control device 50 controls the motor 20 by controlling the power converter 30 and the winding switching device 100. Signal lines extend from the control device 50 to the switches 31u, 32u, 31v, 32v, 31w, and 32w, respectively. The control device 50 controls the on and off states 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 that instructs the winding switching device 100 to switch 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 for detecting the rotational speed of the motor 20 and a torque sensor 202 for detecting the output torque of the motor 20 are mounted on 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 the detection signal output from the rotation sensor 201 and the 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. For example, the gear shift indicator 90 is a shift lever. In other examples, the gear shift indicator 90 is a switch used by the driver to instruct an upshift or downshift. The gear shift indicator 90 outputs a gear shift instruction signal in response to the driver's operation. The control device 50 receives the gear shift instruction signal output from the gear shift indicator 90.

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

[0039] Volatile memory 503 is, for example, a semiconductor memory such as SRAM (static random access memory) or DRAM (dynamic random access memory). Non-volatile memory 502 is, for example, a flash memory, a hard disk, or a ROM (read-only memory). Non-volatile memory 502 stores a control program 510, which is a computer program, and data used when executing control program 510. The various functions of control device 50 are implemented by processor 501 executing control program 510. Control program 510 can be stored in a recording medium such as flash memory, ROM, or CD-ROM. Processor 501 controls power converter 30 and winding switching device 100 using control program 510.

[0040] Processor 501 is, for example, a CPU (central processing unit). However, processor 501 is not limited to a CPU. Processor 501 may also be a GPU (graphics processing unit). Processor 501 is, for example, a multi-core processor. Processor 501 may also be a single-core processor. 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 execute the same processing as control program 510.

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

[0042] [1-2. Structure of the winding switching device] Figure 3 This is a circuit diagram illustrating an example of the structure of a winding switching device according to the first embodiment. Motor 20 includes multiple windings 21u, 22u, 21v, 22v, 21w, and 22w. Windings 21u and 22u correspond to the U phase, windings 21v and 22v correspond to the V phase, and windings 21w and 22w correspond to the W phase. However, the number of windings per phase is not limited to two and may be three or more. Windings 22u, 22v, and 22w are connected at a neutral point 23.

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

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

[0045] Hereinafter, the connection relationship between the winding switching device 100, the power line 35u, and the motor 20 will be described representatively with respect to the U phase. Since the V phase and the W phase are the same, their description will be omitted.

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

[0047] Switching circuit 104u includes relays 111u and 112u. Relays 111u and 112u are, for example, mechanical (electromagnetic) relays, but are not limited to these and can also be semiconductor relays. Relays are 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, or IGBT. A control signal is input to the relay's input side, turning the output-side switch on or off.

[0048] Power line 35u is introduced into winding switching device 100. Within winding switching device 100, power line 35u branches at an intermediate point and is connected to the first terminal of relay 111u. The second terminal of relay 111u is connected to the first terminal of relay 112u. Power lines 212u and 221u extend from motor 20 and are introduced into winding switching device 100. Power line 221u extending from winding 22u is connected to the connection point between the second terminal of relay 111u and the first terminal of relay 112u. Power line 212u extending from winding 21u is connected to the second terminal of 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] The input sides (electromagnetic coil sides) of relays 112u and 111u are each connected to a communication line extending from a control circuit 103u. 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 via communication line 102, indicating the winding connection state. For example, a low level in switching signal SS indicates a first connection state, and a high level in switching signal SS indicates a second connection state. Alternatively, switching signal SS may include data indicating which relay is to be turned 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 to the control device 50.

[0051] The control circuit 103u switches relays 112u and 111u on or off by applying control signals to their respective inputs. Specifically, when the control circuit 103u receives a switching signal SS from the control device 50 that switches the connection state of the windings 21u and 22u from a first connection state to a second connection state, the control circuit 103u switches relay 111u to an on state and relay 112u to an off state. When the control circuit 103u receives a switching signal SS from the control device 50 that switches the connection state of the windings 21u and 22u from a first connection state to a second connection state, the control circuit 103u switches relay 111u to an off state and relay 112u to an on state.

[0052] The control circuit 103u is, for example, composed of multiple logic circuits (such as AND circuits, NOT circuits, and latch circuits). In other examples, the control circuit 103u is composed of a processor. For example, the control circuit 103u is composed of a single-chip microcomputer. The control circuit 103u can also be composed of a programmable logic device such as an ASIC or FPGA.

[0053] Measuring unit 26 is provided on the power line connecting winding switching device 100 and motor 20. Measuring unit 26 includes a phase current sensor and a relay current sensor. Phase current sensor 261u is provided on power line 221u, and relay current sensor 262u is provided on power line 212u. Phase current sensor 261u measures the current flowing through the U phase when 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. Signals or information indicating the value of the current measured by phase current sensor 261u are transmitted to control device 50.

[0054] Relay current sensor 262u measures the current flowing through power line 212u connected to the second terminal of relay 112u. When the connection state of windings 21u and 22u is switched from the first connection state to the second connection state, relay current sensor 262u measures the current flowing through power line 212u, which is to be disconnected by relay 112u, which is set to be disconnected. 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 relay current sensor 262u is transmitted to control device 50.

[0055] Similarly, for the V phase, a phase current sensor 261v is provided on power line 221v, and a relay current sensor 262v is provided on power line 212v. For the W phase, a phase current sensor 261w is provided on power line 221w, and a relay current sensor 262w is provided on power line 212w. It should be noted that when configuring winding switching system 10 without measuring relay current, relay current sensors do not need to be provided.

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

[0057] [1-3. Functions of the control device] Back to Figure 1 The functions of the control device 50 will be described. The control device 50 includes a first opening portion 511, a first determination portion 512, a first connection portion 513, a second opening portion 514, a second determination portion 515, and a second connection portion 516. The functions of the first opening portion 511, the first determination portion 512, the first connection portion 513, the second opening portion 514, the second determination portion 515, and the second connection portion 516 are implemented by the processor 501 executing a control program 510. This description will only be for the U phase, but the same applies to the V and W phases. The following description will use an example in which the connection state switches from the first connection portion state to the second connection portion state, and then switches from the second connection portion state to the first connection portion state.

[0058] [1-3-1. First Opening Section] When the connection state is switched from the first connection state to the second connection state, the first opening portion sets the first relay to be off. The first relay is a relay that is set to be on in the first connection state. Here, the first relay is relay 112u and the second relay is relay 111u.

[0059] Since the initial state is the first connection state, relay 111u is disconnected and relay 112u is connected. Specifically, control device 50 transmits a switching signal SS to control circuit 103u indicating that relay 111u is disconnected and relay 112u is connected. Upon receiving switching signal SS, control circuit 103u disconnects relay 111u and connects relay 112u of switching circuit 104u.

[0060] When the connection state of the winding is switched from the first connection state to the second connection state, first opening portion 511 disconnects relay 112u, which serves as the first relay. Specifically, control device 50 transmits switching signal SS to control circuit 103u, for example, indicating that relay 112u should be disconnected. Upon receiving switching signal SS, control circuit 103u disconnects relay 112u of switching circuit 104u.

[0061] [1-3-2. First Judgment Unit] The first determination unit determines whether the contact of the first relay, which has been set to be OFF by the first opening unit, is in an open state.

[0062] [Relay cuts off current] A mechanical relay consists of an electromagnet and a switch. When the relay is an A-contact relay, if the current flowing through the relay's electromagnet stops, the relay is set to open. A-contact relays are also called normally open relays. If the current stops, the electromagnet, which acts as a magnet, loses its function as a magnet, and the movable piece of the relay switch, which is attracted by the electromagnet, is pulled apart by the force of an elastic body such as a spring. As the movable piece is pulled apart, the first contact provided on the movable piece of the switch and the second contact provided on the fixed piece are pulled apart. As the first contact and the second contact are pulled apart, they are in an open state, thereby cutting off the current flowing through the switch. Therefore, from the time the current in the relay's electromagnet stops to the time the current flowing through the switch is cut off, a period of about 10 milliseconds is required, accompanied by mechanical action. It should be noted that the time from the time the current in the relay's electromagnet stops to the time the current flowing through the switch is cut off is sometimes referred to as the relay's recovery time.

[0063] Furthermore, mechanical relays have different recovery times due to manufacturing variations. Furthermore, to protect the driving element of the relay's electromagnet, such as a MOSFET, a diode is sometimes connected in parallel with the relay's electromagnet. This occurs because the diode allows magnetic energy accumulated in the electromagnet's coil to flow back through it, absorbing it as a return current through the electromagnet and diode. While this return current gradually decays, when it reaches a sufficient level to attract the switch's movable piece, the switch becomes electrically conductive. Consequently, the relay's recovery time can sometimes be unexpectedly prolonged.

[0064] Therefore, the first determination unit 512 of the present disclosure determines whether the contacts of the first relay, which have been set to open by the first opening unit, are in the open state. Specifically, for example, when the current measured by the current sensor that measures the current flowing through the switch including the contacts of the first relay is below a threshold value, the first determination unit 512 determines that the contacts of the first relay are in the open state.

[0065] [When a current sensor is installed on a power line connecting a relay to a motor winding] Figure 4 1 is a circuit diagram showing an example of the structure of the current sensor and the winding according to the first embodiment. Figure 4 In FIG, the current sensor for measuring the current flowing through the switch including the contact of the first relay is the phase current sensor 261u. Figure 4Only the U phase is shown, but the same applies to the V and W phases. A phase current sensor 261u is inserted into the power line 221u connecting the connection point between the second terminal of relay 111u and the first terminal of relay 112u and the first terminal of winding 22u. Phase current sensor 261u measures the current flowing in power line 221u.

[0066] First, the current flowing through the switch, including the contacts of the first relay set to open, is measured. In the first connection state, the relay set to on is relay 112u. Therefore, relay 112u corresponds to the first relay. On the other hand, in the first connection state, the relay set to off is relay 111u. Therefore, relay 111u corresponds to the second relay. Furthermore, when switching from the first connection state to the second connection state, the first opening portion 511 switches relay 112u, serving as the first relay, from on to off. On the other hand, while relay 112u is switched from on to off, relay 111u is not set to on. As a result, phase current sensor 261u only measures the current flowing through the path between winding 21u, relay 112u, and winding 22u. Therefore, phase current sensor 261u can measure the current flowing through the switch, including the contacts of relay 112u.

[0067] [When the current sensor is installed on the power line connecting the power supply circuit and the motor] In the above description, the phase current sensor 261u is described as an example of a current sensor for measuring the current flowing through the switch including the contacts of the first relay, but it is not limited to a phase current sensor. The current sensor may also be provided in the power line connecting the power supply circuit and the motor. Figure 1 In the example, power converter 30 corresponds to the power supply circuit. Current sensor 33u corresponds to the current sensor that measures the current flowing through the first relay. Current sensor 33u is provided on power line 35u connecting power converter 30 and motor 20. It should be noted that the current sensor can be provided in either power converter 30 or winding switching device 100.

[0068] Even in this case, relay 112u functions as the first relay, and relay 111u functions as the second relay. Furthermore, when switching from the first connection state to the second connection state, first opening portion 511 switches relay 112u, acting as the first relay, from on to off. On the other hand, while relay 112u is switching from on to off, relay 111u is not switched on. As a result, current sensor 33u, by measuring the current flowing through power line 35u, only measures the current flowing through the path between winding 21u, relay 112u, and winding 21u. Therefore, current sensor 33u can measure the current flowing through the switch of relay 112u.

[0069] [Judgment method] When the current measured by the current sensor is equal to or lower than the threshold value, the first determination unit 512 determines that the contact of the first relay is in the open state.

[0070] Specifically, when the current measured by phase current sensor 261u or current sensor 33u is below a threshold value, the contacts of relay 112u, the first relay, are determined to be open. The threshold value can be set to a value close to zero, but can also be set to a value lower than the normal current to take into account noise, etc.

[0071] [1-3-3. First connection] When the first determination unit determines that the contact of the first relay is in the open state, the first connection unit turns on the second relay.

[0072] In this example, the first relay is relay 112u, and the second relay is relay 111u. Therefore, when the first determination unit 512 determines that the contacts of relay 112u are open, the first connection unit 513 turns on relay 111u. Specifically, for example, the first connection unit 513 transmits a switching signal SS to the control circuit 103u indicating that relay 111u is turned on. Upon receiving the switching signal SS, the control circuit 103u turns on relay 111u. This sets the connection state of windings 21u and 22u to the second connection state.

[0073] It should be noted that while the above example illustrates a case where the first open portion 511, the first determination portion 512, and the first connection portion 513 are provided in the control device 50, the first open portion 511, the first determination portion 512, and the first connection portion 513 may also be provided in the control circuit 103u. In this case, the control circuit 103u is composed of, for example, a single-chip microcomputer. The single-chip microcomputer includes a processor, non-volatile memory, volatile memory, etc. A control program is stored in the non-volatile memory. The control program is executed by the processor of the single-chip microcomputer to realize the functions of the first open portion 511, the first determination portion 512, and the first connection portion 513. The phase current sensor 261u can transmit data including a signal or information indicating the value of the measured current to the control circuit 103u.

[0074] Furthermore, first opening portion 511 can transmit a power reduction instruction to the power supply circuit that supplies power to the drive motor, thereby opening the first relay. For example, when first opening portion 511 transmits a power reduction instruction, control device 50, having received the power reduction instruction, controls power converter 30 to disconnect or reduce the power to drive motor 20. By opening the relay when the current flowing through the winding is low, the possibility of relay contacts welding can be reduced, thereby extending the life of the relay.

[0075] Furthermore, the first connection unit can turn on the second relay and notify the power supply circuit that supplies the electric power to the drive motor that an instruction to restore the suppressed electric power to its pre-suppression state is given. For example, upon receiving the instruction to restore the suppressed electric power to its pre-suppression state, control device 50 controls power converter 30 to restore the current driving motor 20 to its pre-suppression state. After the winding switching system switches the winding connection state, motor 20 can quickly return to its original state.

[0076] In addition, when the connection state is switched from the first connection state to the second connection state, the first opening portion may also set the first relay to be disconnected when receiving a notification indicating that the power to the drive motor has been suppressed. For example, the control device 50 first controls the power converter 30 to disconnect or suppress the power to the drive motor 20. The control device 50 also sends a notification indicating that the power to the drive motor has been suppressed to the first opening portion 511. The first opening portion 511, having received the notification indicating that the power has been suppressed, sets the first relay to be disconnected. In this way, the relay can be set to be disconnected when the current flowing through the winding is small, which can suppress the possibility of welding of the relay contacts and extend the life of the relay.

[0077] [1-3-4. Second Opening Section] The second opening portion turns off the second relay when the connection state is switched from the second connection state to the first connection state.

[0078] In this example, the first relay is relay 112u, and the second relay is relay 111u. Therefore, when the connection state is switched from the second connection state to the first connection state, second opening portion 514 disconnects relay 111u, which serves as the second relay. Specifically, control device 50 transmits switching signal SS to control circuit 103u, for example, indicating that relay 111u should be disconnected. Upon receiving switching signal SS, control circuit 103u disconnects relay 111u of switching circuit 104u.

[0079] [1-3-5. Second Judgment Unit] The second determination unit 515 determines whether the contacts of the second relay, which have been opened by the second opening unit, are in the open state. Specifically, for example, when the current measured by the current sensor for measuring the current flowing through the switch including the contacts of the second relay is below a threshold value, the second determination unit 515 determines that the contacts of the second relay are in the open state.

[0080] First, the current flowing through the switch including the contacts of the second relay set to open is measured. Since the second relay is relay 111u, when the current measured by the current sensor measuring the current flowing through the switch of relay 111u is below a threshold value, the second determination unit 515 determines that the contacts of relay 111u, which is the second relay, are in an open state.

[0081] When switching from the second connection portion state to the first connection state, the second opening portion 514 sets the relay 111u, which serves as the second relay, from being on to being off. On the other hand, during the period when the relay 111u is set from being on to being off, the relay 112u, which serves as the first relay, has not yet been set to being on. As a result, the phase current sensor 261u will only measure the current flowing through the path between the relay 111u and the winding 22u. Therefore, the phase current sensor 261u can measure the current flowing through the switch of the relay 112u. In addition, the same applies to the case where the current sensor is provided in 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 in the open state based on the current measured by the current sensor 33u.

[0082] Therefore, regardless of whether the winding connection state switches from the first connection state to the second connection state or from the second connection state to the first connection state, phase current sensor 261u can measure the current flowing through the switches of relays 111u and 112u. Therefore, the first and second determination units can share a current sensor, but this is not limiting. Separate current sensors may also be provided for the first and second relays.

[0083] [1-3-6. Second connection] The second connection unit turns on the first relay when the second determination unit determines that the contacts of the second relay are open. In this example, since the first relay is relay 112u, the second connection unit 516 turns on relay 112u when the second determination unit 515 determines that the contacts of relay 111u are open. More specifically, the second connection unit 516 transmits a switching signal SS to the control circuit 103u indicating that relay 112u is turned on. Upon receiving this switching signal SS, the control circuit 103u turns on relay 112u. As a result, the connection state of windings 21u and 22u is set 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 causing the processor 501 to execute the control program 510.

[0085] Figure 5 This is a flowchart showing an example of the winding switching process performed by the control device according to the first embodiment. Figure 6 This is a timing chart showing an example of winding switching processing performed by the control device according to the first embodiment. The following description uses an example in which the control device 50 switches the connection state of the winding from the first connection state to the second connection state, and then switches from the second connection state to the first connection state.

[0086] [Step S101] In this example, since the initial state is the first connection state, control device 50 transmits switching signal SS to control circuit 103u, indicating that relay 111u is to be disconnected and relay 112u is to be connected (step S101), and the process proceeds to step S102. Upon receiving switching signal SS, control circuit 103u disconnects relay 111u and connects relay 112u. Figure 6 The position of State 1 in the timing diagram shown is this state.

[0087] [Step S102] When the connection state is switched from the first connection state to the second connection state, first opening unit 511 turns off the first relay (step S102). In this example, the first relay is relay 112u, and first opening unit 511 turns off relay 112u, which was previously on. After the control device 50 turns off relay 112u, the process proceeds to step S102. Figure 6 The position where the transition from state 1 to state 2 occurs in the timing diagram shown is this state.

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

[0089] First, the current flowing through the contact of the first relay set to open is measured. The first relay is 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 phase current sensor 261u or current sensor 33u is below the threshold, first determination unit 512 determines that the contacts of relay 112u are open ("Yes" in step S103), and the process proceeds to step S104. On the other hand, if the current measured by phase current sensor 261u or current sensor 33u is above the threshold, first determination unit 512 determines that the contacts of relay 112u are not open ("No" in step S103), and the process returns to step S103. Phase current sensor 261u or current sensor 33u measures the current again, and first determination unit 512 determines whether the measured current is below the threshold. Figure 6 The position of State 2 in the timing diagram shown is this state.

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

[0092] If first determination unit 512 determines that the contacts of relay 112u are open ("YES" in step S103), first connection unit 513 transmits switching signal SS to control circuit 103u, indicating that relay 111u, serving as the second relay, should be turned on. Control circuit 103u, receiving switching signal SS, turns on relay 111u. Consequently, the connection state of windings 21u and 22u is set to the second connection state. Figure 6This state is the position where the state 2 is changed to the state 3 in the timing diagram shown. Next, when the connection state is switched from the second connection state to the first connection state, step S105 is entered.

[0093] [Step S105] When the connection state is switched from the second connection state to the first connection state, second opening unit 514 sets the second relay to off (step S105). In this example, the second relay is relay 111u. Second opening unit 514 sets relay 111u, which was previously on, to off. After the control device 50 sets relay 111u to off, the process proceeds to step S106. Figure 6 The transition from state 3 to state 4 in the timing diagram shown is this state.

[0094] [Step S106] The second determination unit determines whether the contact of the second relay, which has been set to be 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 set to be open. 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 phase current sensor 261u or current sensor 33u is below the threshold, second determination unit 515 determines that the contacts of relay 111u are open ("Yes" in step S106), and the process proceeds to step S107. On the other hand, if the current measured by phase current sensor 261u or current sensor 33u is above the threshold, second determination unit 515 determines that the contacts of relay 111u are not open ("No" in step S106), and the process returns to step S106. Phase current sensor 261u or current sensor 33u measures the current again, and second determination unit 515 determines whether the measured current is below the threshold. Figure 6 The position of state 4 in the timing diagram shown is this state.

[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 turns on the first relay (step S107 ).

[0098] If second determination unit 515 determines that the contacts of relay 111u are open ("YES" in step S106), second connection unit 516 transmits switching signal SS to control circuit 103u, indicating that relay 112u should be turned on. Upon receiving switching signal SS, control circuit 103u turns relay 112u on. Consequently, the connection state of windings 21u and 22u is set to the first connection state. Figure 6 This state is the position where the state 4 transitions to the state 5 in the timing chart shown. After the relay 112u is turned 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 vice versa, the winding connection state is switched after the contacts of relays 111u and 112u are in the open state. This prevents the winding from short-circuiting, even when multiple relays are used, and suppresses the generation of large induced currents, torque fluctuations, and contact sticking caused by high currents. From these perspectives, the present disclosure is preferably applied to mechanical relays.

[0100] For ease of explanation, the U, V, and W phases are described as independent from each other. However, the winding connection status can also be changed simultaneously for each phase. In this case, when the current sensor values ​​for the U, V, and W phases all reach zero, the relay contacts are judged to be open, and the connection status is switched, avoiding inconsistencies between the phases. Furthermore, by using a relay that simultaneously opens and closes multiple circuits with a single coil, all phase circuits can be opened and closed simultaneously. This allows all phases to be operated simultaneously by controlling a single relay, simplifying the circuit design and control.

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

[0102] [2-1. Structure of the winding switching device] Figure 7 This is a circuit diagram showing an example of the configuration of a winding switching device and a measuring unit in the second embodiment. The second embodiment differs from the first embodiment in the configuration of the measuring unit 26; the other configurations are the same. Descriptions of configurations identical to those in the first embodiment will be omitted, and only the differences will be described. Identical configurations will be referenced using the same reference numerals.

[0103] [Measurement Department] Measuring 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. 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. Voltage sensor 272u measures the voltage across the switch of relay 112u. The voltage sensors transmit information or signals indicating the measured voltages to control device 50. The same applies to V-phase and W-phase.

[0104] [2-2. Functions of the control device] The second embodiment differs from the first embodiment in the functions of the first determination unit 512 and the second determination unit 515. The other functions are the same. In addition, the first determination unit 512 and the second determination unit 515 measure different relays, but the functions are the same.

[0105] [First judgment unit, second judgment unit] 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 the voltage of the first relay.

[0106] First, first determination unit 512 measures the voltage across the output switch of the first relay, which is set to OFF. When the winding connection state switches from the first connection state to the second connection state, the relay in the first connection state, i.e., the relay set to ON in the first connection state, is relay 112u, which corresponds to the first relay. Therefore, voltage sensor 272u measures the voltage across the switch of 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 are in the open state based on the voltage across the switch of the relay 111u as the second relay measured by the voltage sensor 271u.

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

[0109] In other words, as the relay switch contacts open, one end of the stator windings 21u and 22u becomes open. As the rotor of motor 20 rotates, a voltage is generated in the stator windings 21u and 22u that is significantly different from zero. Voltage sensors 271u and 272u measure this voltage, and if it exceeds a threshold, they determine that the relay output switch is electrically open. [1-4. Operation of the winding switching system] The second embodiment differs from the first embodiment in the operations of step S103 and step S106, and the other operations are the same. The relays measured in step S103 and step S106 are different, but the operations are the same.

[0110] [Step S103] The first determination unit determines whether the contact of the first relay, which has been set to be 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 relay 112u. The voltage sensor 272u measures the voltage across the switch of the relay 112u.

[0112] If the voltage measured by voltage sensor 272u is greater than the threshold, the switch contacts are determined to be in the open state ("Yes" in step S103), and the process proceeds to step S103. On the other hand, if the voltage measured by voltage sensor 272u is less than the threshold, the switch contacts are determined to be not in the open state ("No" in step S103), and the process returns to step S103, where the first determination unit 512 determines whether the voltage measured again by voltage sensor 272u is greater than the predetermined threshold.

[0113] As described above, even with a voltage sensor, it's possible to determine whether the relay contacts are open. Therefore, in the second embodiment, the winding connection state is switched after both the switch contacts of relays 111u and 112u are open. This prevents winding short-circuits, even when multiple relays are used, and suppresses the generation of large induced currents, torque fluctuations, and contact sticking caused by high currents.

[0114] [3. Third embodiment] The vehicle motor drive system according to the third embodiment includes: an AC motor that drives the wheels of the vehicle, wherein each phase of the AC motor has a plurality of windings; a power converter that converts DC power into three-phase AC power for driving the AC motor; and a winding switching system that switches the connection state of the plurality of windings.

[0115] The AC motor that drives the vehicle's wheels is the electric motor 20 used for driving the electric vehicle. Specifically, the electric motor 20 is connected to the wheels 60 to drive them. The electric motor 20 is driven by three-phase AC power. Each stator phase of the electric motor 20 includes multiple windings. The characteristics of the electric motor 20 can be changed by switching the multiple windings.

[0116] Power converter 30 is an inverter that converts DC power supplied from battery 40 into three-phase AC power. Power converter 30 includes a bridge arm for each phase. Each bridge arm includes a switch. The switch performs a switching operation to convert DC power into three-phase AC power.

[0117] The winding switching system 10 is a winding switching system that switches the connection state of the multiple windings of an electric motor whose stator includes multiple windings in each phase. The winding switching system 10 includes a first relay, a second relay, a first opening portion, a first determination portion, and a first connection portion. The first relay is set to be conductive when the connection state of the multiple windings is the first connection state. The second relay is set to be disconnected when the connection state of the multiple windings is the first connection state. When the connection state is switched from the first connection state to the second connection state, the first opening portion sets the first relay to be disconnected. The first determination portion determines whether the contacts of the first relay, which have been set to be disconnected by the first opening portion, are in an open state. When the first determination portion determines that the contacts of the first relay are in an open state, the first connection portion sets the second relay to be conductive.

[0118] As described in the first embodiment, the winding switching system 10 incorporates this structure. When the winding connection state is switched, all relays involved in the winding connection state switching are set to the disconnected state, and the connection state is switched. This prevents winding short-circuits even when multiple relays are used, suppressing the generation of large induced currents, torque fluctuations, and contact sticking caused by high currents. Furthermore, even in a vehicle equipped with this winding switching system 10, it prevents multiple relays from being simultaneously connected.

[0119] [4. Modification] The winding switching system may further include a third relay that is set to be disconnected when the connection state of the plurality of windings is the first connection state. The first terminal of the third relay is connected to the second terminal of the first winding, and the second terminal of the third relay is connected to the second terminal of the second winding. When the connection state is switched from the first connection state to the second connection state, the first connection portion sets the third relay to be turned on. Figure 8In the embodiment, the third relay is relay 113u. In addition, as the connection state of the second winding, there are 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. In the second connection state, the first windings may also be connected in parallel.

[0120] Figure 8 1 is a circuit diagram showing an example of the configuration of a modified example of the winding switching device 100 . Figure 8 Only the U phase is shown, but the same applies to the V phase and the W phase. Compared to the first embodiment, a relay 113u is added. The relay 113u is set to be on or off at the same time as the relay 111u. By adding the relay 113u, the winding 21u and the winding 22u can be connected in parallel. Hereinafter, the parallel connection situation is sometimes referred to as the second connection state. In the case of parallel connection, the relays 111u and 113u are set to be on, and the relay 112u is set to be off. On the other hand, in the case of the first connection state, that is, the series connection, the relays 111u and 113u are set to be off, and the relay 112u is set to be 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 vice versa. Even in this case, when the winding connection state switches between the first and second connection states, all relays that switch the winding connection state are set to either on or off, rather than being set to an off state. This prevents winding short-circuits, even when multiple relays are used, and suppresses the generation of large induced currents, torque fluctuations, and contact sticking caused by high currents.

[0122] [5. Supplementary Note] The embodiments disclosed herein are in all respects illustrative and non-restrictive. The scope of the present invention is defined by the claims, not the embodiments described above, and encompasses all modifications within the meaning and scope of the claims. Furthermore, while the present invention is described using automotive electric motors as an example, this is not limited to automotive electric motors and is also applicable to AC electric motors that utilize multiple relays to switch multiple windings to change characteristics. Description of Reference Numerals

[0123] 10 Winding switching system

[0124] 20 Electric motor (drive motor)

[0125] 21u, 22u, 21v, 22v, 21w, 22w windings

[0126] 23 Neutral Point

[0127] 25 Power Lines

[0128] 26 Measurement Department

[0129] 30 Power Converters

[0130] 31u, 32u, 31v, 32v, 31w, 32w switches

[0131] 33u, 33v, 33w current sensors

[0132] 35u, 35v, 35w power line

[0133] 40 batteries

[0134] 50 Control Device

[0135] 501 processor

[0136] 502 Non-volatile Memory

[0137] 503 Volatile Memory

[0138] 504 Interface (I / F)

[0139] 510 Control Program

[0140] 511 First Open Department

[0141] 512 First Judgment Unit

[0142] 513 First connection

[0143] 514 Second Open Section

[0144] 515 Second Judgment Unit

[0145] 516 Second connection

[0146] 60 wheels

[0147] 70 brake pedal

[0148] 71 Sensors

[0149] 80 Accelerator pedal

[0150] 81 Sensors

[0151] 90 Speed ​​indicator

[0152] 100 Winding switching device

[0153] 102 Communication line (switching signal SS)

[0154] 102d Delayed switching signal SS

[0155] 103u, 103v, 103w control circuit

[0156] 104u, 104v, 104w switching circuit

[0157] 111u, 112u, 113u, 111v, 112v, 113v, 111w, 112w, 113w relays

[0158] 201 Rotation Sensor

[0159] 202 Torque sensor

[0160] 212u, 221u, 212v, 221v, 212w, 221w power lines

[0161] 261u, 261v, 261w phase current sensors

[0162] 262u, 262v, 262w relay current sensors

[0163] 271u, 272u, 271v, 272v, 271w, 272w voltage sensors.

Claims

1. A winding switching system for switching the connection states of a plurality of windings of an electric motor having a stator of each phase including the plurality of windings. The winding switching system comprises: a first relay configured to be turned on when the connection state of the plurality of windings is a first connection state; a second relay, configured to be disconnected when the connection state of the plurality of windings is the first connection state; a first opening portion configured to disconnect the first relay when the connection state is switched from the first connection state to the second connection state; a first determination unit for determining whether the contact of the first relay, which has been set to be open by the first opening unit, is in an open state; and The first connecting unit turns on the second relay when the first determining unit determines that the contact of the first relay is in the open state.

2. The winding switching system according to claim 1, wherein: The winding switching system further comprises: a second opening portion, configured to disconnect the second relay when the connection state is switched from the second connection state to the first connection state; a second determination unit for determining whether the contact of the second relay, which has been set to be open by the second opening unit, is in an open state; and The second connecting unit turns on the first relay when the second determining unit determines that the contact of the second relay is in the open state.

3. The winding switching system according to claim 1 or 2, wherein: The first determination unit determines that the contacts of the first relay are in an open state when a current measured by a current sensor that measures a current flowing through a switch including the contacts 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 winding of the motor.

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

6. 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 a switch including the contact of the first relay.

7. The winding switching system according to any one of claims 1 to 6, wherein: The plurality of windings include a first winding and a second winding, The first terminal of the first relay is connected to the second terminal of the first winding, The second terminal of the first relay is connected to the first terminal of the second winding, The first terminal of the second relay is connected to the first terminal of the second winding, The second terminal of the second relay is connected to the first terminal of the first winding.

8. The winding switching system according to claim 7, wherein: The winding switching system further includes a third relay that is set to be open when the connection state of the plurality of windings is the first connection state. The first terminal of the third relay is connected to the second terminal of the first winding, The second terminal of the third relay is connected to the second terminal of the second winding, When the connection state is switched from the first connection state to the second connection state, the first connection unit turns on the third relay.

9. The winding switching system according to any one of claims 1 to 8, wherein: The first opening portion notifies a power supply circuit that supplies power for driving the motor of an instruction to suppress the power, and turns off the first relay.

10. The winding switching system according to claim 9, wherein: The first connection unit turns on the second relay and notifies the power supply circuit that supplies power for driving the motor of an instruction to restore the suppressed power to a state before suppression.

11. The winding switching system according to any one of claims 1 to 8, wherein: When the connection state is switched from the first connection state to the second connection state, the first opening portion opens the first relay upon receiving a notification indicating that the electric power for driving the motor has been suppressed.

12. A vehicle electric motor drive system comprising: an AC motor for driving wheels of the vehicle, wherein each phase stator of the AC motor includes a plurality of windings; a power converter for converting direct current into three-phase alternating current for driving the alternating current motor; and The winding switching system according to any one of claims 1 to 11 switches the connection states of the plurality of windings.

13. A control device for controlling a winding switching device for switching connection states of a plurality of windings of an electric motor having a stator of each phase including the plurality of windings. The control device comprises: an opening unit configured to, when the connection state of the plurality of windings is switched from a first connection state to a second connection state, open a first relay that is set to be on when the connection state is the first connection state; a determination unit for determining whether the contact of the first relay, which has been set to be open by the first opening unit, is in an open state; and The connecting unit turns on the second relay that was turned off when the connection state of the plurality of windings is the first connection state, when the determining unit determines that the contact of the first relay is in the open state.

14. A winding switching method, comprising switching the connection states of a plurality of windings of a motor having a stator of each phase including the plurality of windings, The winding switching method comprises the following steps: When the connection state of the plurality of windings is switched from a first connection state to a second connection state, setting the first relay, which is set to be on when the connection state is the first connection state, to be off; determining whether the contact of the first relay, which has been set to be open by the first opening portion, is in an open state; and When it is determined that the contact of the first relay is in the open state, the second relay, which was set to be off when the connection state of the plurality of windings is the first connection state, is set to be on.

15. A computer program for use by a winding switching device for switching connection states of a plurality of windings of a motor having a stator of each phase including the plurality of windings, the computer program causing a computer to execute the following steps: When the connection state of the plurality of windings is switched from a first connection state to a second connection state, setting the first relay, which is set to be on when the connection state is the first connection state, to be off; determining whether the contact of the first relay, which has been set to be open by the first opening portion, is in an open state; and When it is determined that the contact of the first relay is in the open state, the second relay, which was set to be off when the connection state of the plurality of windings is the first connection state, is set to be on.

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