JP2013070492A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of components of a relay attached in an electric power line between an inverter and a motor, and determine abnormality due to deposition of the relay.SOLUTION: A relay 74 for a motor consisting of a U-phase relay 74u and a V-phase relay 74v is attached to two power lines of U-phase and V-phase of a three-phase AC power line between an inverter 34 and a motor 32. When an ignition switch is turned off, transistors T11, T12 and T16 in the inverter 34 are turned on for a prescribed time in such a condition that the relay 74 for the motor is off, and a closed circuit including a capacitor 48, the relay 74 for the motor, and W-phase of the three-phase AC power line is formed. When a voltage Vc1 of the capacitor 48 after forming and terminating the closed circuit is lower than a voltage obtained by subtracting a prescribed voltage ΔV from a voltage Vc0 of the capacitor 48 before forming the closed circuit, an abnormality due to deposition is determined in the relay 74 for the motor.

Description

  The present invention relates to a power supply device, and more specifically, a DC power supply, an inverter circuit that converts DC power from the DC power supply into three-phase AC power and supplies the three-phase AC motor, and a terminal between the DC power supply side of the inverter circuit. And a smoothing capacitor connected to the power supply device. The power supply device is mounted on a vehicle together with a three-phase AC motor.

  Conventionally, as this type of power supply device, a power supply device mounted on a tracked carriage and having a contactor relay attached to each of the U phase, V phase, and W phase of the power line from the inverter to the three-phase AC motor has been proposed. (For example, refer to Patent Document 1). In this device, when the emergency stop button is turned on, the inverter and the three-phase AC motor are shut off and the mechanical brake is activated by turning off the contactor relays for each of the U phase, V phase, and W phase. This makes it possible to make an emergency stop of the carriage.

Japanese Patent Laid-Open No. 07-170601

  However, in the above-described power supply device, even if the emergency stop button is turned on, there may be a case where time is required for the emergency stop. A relay such as a contactor relay may cause an abnormality due to welding due to application of an overcurrent. When an abnormality due to welding has occurred in the contactor relay, even if the emergency stop button is turned on, the inverter and the three-phase AC motor cannot be shut off. Further, since the contactor relay is attached to each of the U-phase, V-phase, and W-phase of the power line from the inverter to the three-phase AC motor, the number of parts increases, and the frequency of occurrence of abnormality increases.

  The main purpose of the power supply device of the present invention is to reduce the number of parts of the relay attached to the power line between the inverter and the electric motor, and to determine abnormality due to welding of the relay.

  The power supply apparatus of the present invention employs the following means in order to achieve the main object described above.

The power supply device of the present invention is
A DC power supply, an inverter circuit that converts DC power from the DC power supply into three-phase AC power and supplies it to a three-phase AC motor, a smoothing capacitor connected between terminals on the DC power supply side of the inverter circuit, A power supply device mounted on a vehicle together with the three-phase AC motor,
A relay for power supply as a pair of relays attached to a positive power line and a negative power line in a direct current power line between the direct current power source and the inverter circuit;
A relay for the motor as a pair of relays attached to any two-phase power line of the three-phase power line between the inverter circuit and the three-phase AC motor;
When the ignition is turned off, the smoothing capacitor, the motor relay, and the three-phase power are turned off with the motor relay turned off after the power supply relay is turned off and before the voltage of the smoothing capacitor is discharged. When the closed circuit including a power line to which the motor relay is not attached is formed and the voltage of the smoothing capacitor drops more than a predetermined voltage before and after forming the closed circuit, the motor included in the closed circuit An abnormality determining means for determining that an abnormality has occurred due to welding of the relay;
It is a summary to provide.

  In the power supply device of the present invention, since the motor relay as a pair of relays is attached to any two-phase power line of the three-phase power line between the inverter circuit and the three-phase AC motor, the three-phase power The number of parts can be reduced as compared with the case where a relay is attached to each line. As a result, the frequency of occurrence of abnormality due to welding of the relay can be reduced. In addition, when the ignition is turned off, after the power supply relay is turned off and before the voltage of the smoothing capacitor is discharged, the electric motor of the smoothing capacitor, the motor relay, and the three-phase power line is turned off with the motor relay turned off. When a closed circuit including a power line to which a relay is not attached is formed and the voltage of the smoothing capacitor drops more than a predetermined voltage before and after the closed circuit is formed, an abnormality due to welding of a motor relay included in the closed circuit occurs. It is determined that Thereby, abnormality due to welding of the motor relay can be determined, and abnormality due to welding of the motor relay can be dealt with.

  In such a power supply device of the present invention, the predetermined voltage is generated by the smoothing capacitor before and after forming the closed circuit with the motor relay turned off when no abnormality has occurred in the motor relay included in the closed circuit. The voltage may be predetermined as a voltage slightly larger than the voltage drop. By so doing, it is possible to determine abnormality due to welding of the motor relay by a simple method.

  In the power supply device of the present invention, a voltage is provided between the power relay and the smoothing capacitor of the DC power line so that the voltage on the smoothing capacitor side is higher than the voltage on the power relay side. And a low-voltage side capacitor provided between the boost circuit of the DC power line and the power supply relay.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 carrying the power supply device as one Example of this invention. It is a block diagram which shows the outline of a structure of the electric drive system of the electric vehicle 20 of an Example. 4 is a flowchart showing an example of a startup process routine executed by the electronic control unit 50. 4 is a flowchart showing an example of an end process routine executed by the electronic control unit 50. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 equipped with a power supply device as one embodiment of the present invention, and FIG. 2 is a configuration showing an outline of an electric motor drive system configuration of the electric vehicle 20 of the embodiment. FIG. As shown in the figure, an electric vehicle 20 according to the embodiment includes, for example, a motor 32 that is configured as a synchronous generator motor and that can input and output power to a drive shaft 22 that is connected to drive wheels 26a and 26b via a differential gear 24. An inverter 34 for driving the motor 32, a battery 36 configured as, for example, a lithium ion secondary battery, a power line 44 connected to the inverter 34 (hereinafter referred to as a high voltage system power line), and a battery 36 are connected. Connected to a power line (hereinafter referred to as a battery voltage system power line) 42 to adjust the voltage VH of the high voltage system power line 44 within the range of the voltage VL of the battery voltage system power line 22 and the maximum allowable voltage VHmax. And a voltage boosting converter for exchanging power between the high voltage system power line 44 and the battery voltage system power line 42. It comprises a chromatography motor 40, the electronic control unit 50 that controls the whole vehicle, the. Further, a system main relay (SMR) 72 for cutting off the battery 36 is attached to the battery voltage system power line 42, and a smoothing capacitor 46 is provided between the system main relay 52 and the boost converter 40. A smoothing capacitor 48 is also attached to the high voltage system power line 44. A motor relay 74 is attached to the U-phase and V-phase power lines of the three-phase AC power line from the inverter 34 to the motor 32.

  The motor 32 is configured as a well-known synchronous generator motor including a rotor in which a permanent magnet is embedded and a stator around which a three-phase coil is wound, and generates a counter electromotive voltage with rotation. As shown in FIG. 2, the inverter 34 includes transistors T11 to T16 as six switching elements, and six diodes D11 to D16 connected in parallel to the transistors T11 to T16 in the reverse direction. The transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus of the high voltage system power line 44, and each of the connection points between the paired transistors. The three-phase coils (U-phase, V-phase, W-phase) of the motor 32 are connected to each other. Therefore, by controlling the ratio of the on-time of the transistors T11 to T16 while the voltage is applied to the inverter 34, a rotating magnetic field can be formed in the three-phase coil, and the motor 32 can be driven to rotate. A smoothing capacitor 46 is connected to the positive and negative buses of the high voltage power line 44. The motor relay 74 includes a U-phase relay 74u attached to the U-phase power line and a V-phase relay 74v attached to the V-phase power line.

  As shown in FIG. 2, the boost converter 40 is configured as a boost converter including two transistors T31 and T32, two diodes D31 and D32 connected in parallel in opposite directions to the transistors T31 and T32, and a reactor L. . The two transistors T31 and T32 are connected to the positive bus of the high voltage system power line 44 and the negative bus of the high voltage system power line 44 and the battery voltage system power line 42, respectively, and the reactor L is connected to the connection point. Has been. The positive terminal and the negative terminal of the battery 36 are connected to the reactor L, the negative voltage bus of the high voltage system power line 44 and the battery voltage system power line 42, respectively. Therefore, by turning on and off the transistors T31 and T32, the battery voltage system power line 42 is boosted and supplied to the high voltage system power line 44, or the high voltage system power line 44 is powered down to reduce the battery voltage. Or can be supplied to the system power line 42.

  As shown in FIG. 2, the system main relay 72 includes a positive side relay 72 a attached to the positive side line of the battery voltage system power line 42 and a negative side relay attached to the negative side line of the battery voltage system power line 42. 72b and a precharging relay 72c connected in series with a resistor so as to bypass the negative side relay 72b.

  The electronic control unit 50 is configured as a microprocessor centered on the CPU 52, and includes a ROM 54 that stores a processing program, a RAM 56 that temporarily stores data, and an input / output port (not shown) in addition to the CPU 52. . The electronic control unit 50 is attached to the rotational position of the rotor of the motor 32 from the rotational position detection sensor 32 a that detects the rotational position of the rotor of the motor 32, or to a connection line (power line) between the motor 32 and the inverter 34. Phase current from a current sensor (not shown), voltage Vb between terminals from a voltage sensor (not shown) installed between terminals of the battery 36, current sensor (not shown) attached to a power line connected to the output terminal of the battery 36 Charge / discharge current, battery temperature from a temperature sensor (not shown) attached to the battery 36, voltage of the capacitor 46 (voltage of the battery voltage system power line 42) VL and capacitor from the voltage sensor 46a attached between terminals of the capacitor 46 The voltage of the capacitor 48 from the voltage sensor 48a attached between the terminals of 48. The voltage of the high-voltage power line 44) VH, the ignition signal from the ignition switch 60, the shift position SP from the shift position sensor 62 that detects the operating position of the shift lever 61, and the accelerator pedal position that detects the amount of depression of the accelerator pedal 63 The accelerator opening Acc from the sensor 64, the brake pedal position BP from the brake pedal position sensor 66 for detecting the depression amount of the brake pedal 65, the vehicle speed V from the vehicle speed sensor 68, and the like are input via the input port. From the electronic control unit 50, the switching control signal to the transistors T11 to T16 of the inverter 34, the switching control signal to the transistors T31 and T32 of the boost converter 40, the drive signal to the system main relay 72, the drive to the motor relay 74 Signals are output via the output port. The electronic control unit 50 also calculates the rotational speed Nm of the motor 32 based on the rotational position of the rotor of the motor 32 from the rotational position detection sensor 32a.

  Here, as the power supply device of the embodiment, the battery 36, the boost converter 40, the inverter 34, the capacitor 46, the capacitor 48, the system main relay 72, the motor relay 74, the electronic control unit 50, Is applicable.

  The electric vehicle 20 of the embodiment configured in this way is driven and controlled by a drive control routine (not shown). In the drive control, a required torque Tr * to be output to the drive shaft 22 is set according to the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68, and the set required torque Tr * is set to the motor. 32 is set as the torque command Tm * to be output from 32, and the voltage required to drive the motor 32 at the operating point consisting of the set torque command Tm * and the rotational speed Nm is set to the target voltage VH of the high voltage system power line 44. * Is set as *, and the step-up converter controls the transistors T11 to T16 of the inverter 34 so that the motor 32 is driven by the set torque command Tm * and the voltage VH of the high voltage system power line 44 becomes the target voltage VH *. Forty transistors T31 and T32 are subjected to switching control. When the vehicle is decelerated by traveling off while traveling, a required torque Tr * (negative torque) is set as a braking force in accordance with the amount of depression of the brake pedal 65 and the vehicle speed V, and of the set required torque Tr * Torque that can be output within the rated value range of the motor 32 is set as the torque command Tm *, and the voltage required to drive the motor 32 at the operating point consisting of the set torque command Tm * and the rotation speed Nm is increased. The target voltage VH * of the voltage system power line 44 is set, and the transistors T11 to T16 of the inverter 34 are switched and controlled so that the motor 32 is driven by the set torque command Tm *, and the voltage VH of the high voltage system power line 44 is The transistors T31 and T32 of the boost converter 40 are subjected to switching control so that the target voltage VH * is obtained. Of the required torque Tr * as the braking force, the braking torque that is insufficient for the braking torque output from the motor 32 controls the hydraulic brake device so that the corresponding braking force is output from a hydraulic brake device (not shown). Then, when the vehicle speed decreases, processing for replacing the braking force by the motor 32 with the braking force by the hydraulic brake device is performed in order to smoothly stop the vehicle without causing a shock to the vehicle.

  Next, the operation of the electric vehicle 20 of the embodiment thus configured, in particular, the operation of the power supply device in the process (start-up process) at the time of starting the system when the ignition switch 60 is turned on, and the ignition switch 60 is turned off. The operation of the power supply device in the process at the time of system stop (end process) will be described. FIG. 3 is a flowchart showing an example of a startup processing routine executed by the electronic control unit 50 when the ignition switch 60 is turned on, and FIG. 4 shows that the ignition switch 60 is turned off while the system is running. 7 is a flowchart illustrating an example of an end processing routine that is sometimes executed by an electronic control unit 50. Hereinafter, first, the startup process will be described, and then the end process will be described.

  When the startup process routine is executed, the CPU 52 of the electronic control unit 50 first checks whether an abnormality has occurred in the system (step S100). The abnormality is stored in a predetermined area of the RAM 56 when it is determined that an abnormality has occurred in any of the systems by the end process described later or an abnormality check of drive control (not shown) before the previous end process. By checking whether or not an abnormality is stored in a predetermined area of the RAM 56, the abnormality can be checked.

  If it is determined that no abnormality has occurred (step S110), the capacitor 46 connected to the battery voltage system power line 42 is precharged (step S120). When the precharge is completed, the system main relay 72 is turned on. At the same time (step S130), the motor relay 74 is turned on (step S140), the shutdown signal of the gate of the inverter 34 is released (step S150), the system startup is completed, and this routine is terminated. Here, the capacitor 46 is precharged by turning on the positive side relay 72a and the precharging relay 72c of the system main relay 72, and the system main relay 72 is kept on while the positive side relay 72a is on. The precharge relay 72c is turned off while the negative side relay 72b is turned on. The motor relay 74 is turned on by turning on both the U-phase relay 74u and the V-phase relay 74v. As a result, the system can be started up without applying an inrush current to the capacitor 46. The precharge of the capacitor 46 of the high voltage system power line 44 can be performed by on / off control of the transistors T31 and T32 of the boost converter 40.

  On the other hand, if it is determined in step S110 that an abnormality has occurred, the abnormality is notified by turning on an abnormal lamp attached in the vicinity of the driver's seat or outputting a voice indicating that an abnormality has occurred (step S160). ) This routine is terminated without starting the system. As a result, it is possible to avoid inconveniences caused by system startup when an abnormality occurs in any of the systems, for example, damage to devices constituting the system.

  Next, the termination process will be described. When the end processing routine of FIG. 4 is executed, the CPU 52 of the electronic control unit 50 first turns off the system main relay 72 (step S200), and turns off the motor relay 74 (step S210). A welding abnormality check is performed to determine whether or not abnormality has occurred in either one of the 74 U-phase relay 74u or V-phase relay 74v (step S220). Here, the system main relay 72 is turned off by turning off both the positive-side relay 72a and the negative-side relay 72b that are turned on, and the motor relay 74 is turned off when the U-phase relay 74u is turned on. And V-phase relay 74v are both turned off. In the welding abnormality check, first, the voltage VH from the voltage sensor 48a is input as the voltage Vc0 of the capacitor 48 before the check (step S222), and only the transistors T11, T12, T16 of the inverter 34 are set for a predetermined time (for example, The closed circuit including the capacitor 48, the motor relay 74 (the U-phase relay 74u and the V-phase relay 74v), and the W phase to which no relay is attached is formed in the three-phase AC power line. At the same time (step S224), after the formation of the closed circuit is canceled, the voltage VH from the voltage sensor 48a is input as the voltage Vc1 of the capacitor 48 after the closed circuit is formed (step S226), and the voltage Vc1 is changed from the voltage Vc0 to a predetermined voltage. Motor relay depending on whether it is smaller than the one reduced by ΔV 4 determines whether the abnormality due to at least one the welding of U-phase relay 74u or V-phase relay 74v has occurred (step S228), carried out by. Here, the predetermined voltage ΔV is closed by turning on only the transistors T11, T12, and T16 of the inverter 34 for a predetermined time when there is no abnormality due to welding in the U-phase relay 74u and the V-phase relay 74v of the motor relay 74. A value slightly larger than the voltage drop of the capacitor 48 when the circuit is formed is predetermined by an experiment or the like. Therefore, even if the U-phase relay 74u and the V-phase relay 74v of the motor relay 74 are not abnormal due to welding, the transistors T11, T12, T16 of the inverter 34 are turned on for a predetermined time to form a closed circuit. The voltage Vc1 becomes larger than the voltage Vc0 reduced by the predetermined voltage ΔV, and if an abnormality due to welding occurs in one or both of the U-phase relay 74u and the V-phase relay 74v of the motor relay 74, an abnormality due to welding occurs. Since current flows through the relay, the voltage Vc1 becomes smaller than the voltage Vc0 subtracted by the predetermined voltage ΔV. Thereby, abnormality due to welding of the motor relay 74 can be determined.

  When the welding abnormality check is completed and it is determined that there is no abnormality due to welding in the motor relay 74 (step S230), the motor relay 74 is turned on (step S240) and the capacitor 48 is discharged (step S230). S250) After the discharge is finished, the motor relay 74 is turned off (step S260), and this routine is finished. Here, the capacitor 48 is discharged by switching the transistors T11 to T16 of the inverter 34 so that the electric charge stored in the capacitor 48 flows into the motor 32 and is consumed as heat by the motor 32.

  On the other hand, when it is determined in step S230 that an abnormality due to welding has occurred in the motor relay 74, the abnormality due to welding of the motor relay 74 is stored in a predetermined area of the RAM 56 (step S270) and attached near the driver's seat. The abnormal light is turned on or a sound is output to indicate that an abnormality has occurred, and the abnormality is notified (step S280), and this routine is terminated without discharging the capacitor 48. Since the abnormality due to welding of the motor relay 74 is stored in a predetermined area of the RAM 56, the next time the activation processing routine of FIG. 3 is executed, it is determined that an abnormality has occurred and the system is not activated.

  According to the power supply apparatus of the embodiment described above, the U-phase relay 74u and the V-phase relay 74v are connected to two U-phase and V-phase power lines among the three-phase AC power lines between the inverter 34 and the motor 32. When the ignition relay 60 is turned off and the motor relay 74 is turned off, only the transistors T11, T12, T16 of the inverter 34 are turned on for a predetermined time and the capacitor 48 and the motor relay 74 are turned on. And the W phase of the three-phase AC power line are formed, and the voltage Vc1 of the capacitor 48 after the closed circuit is formed and released is changed from the voltage Vc0 of the capacitor 48 before the closed circuit is formed to a predetermined voltage ΔV It is possible to determine whether or not an abnormality due to welding has occurred in the motor relay 74 by comparing with that obtained by subtracting That. Of course, the inverter 34 and the motor 32 can be disconnected by turning off the motor relay 74 when a one-phase short-circuit failure of the inverter 34 occurs.

  In the power supply device of the embodiment, when the ignition switch 60 is turned off, only the transistors T11, T12, T16 of the inverter 34 are turned on for a predetermined time with the motor relay 74 turned off. Although a closed circuit including the W phase of the three-phase AC power line is formed, only the transistors T11 and T16 of the inverter 34 are turned on for a predetermined time while the motor relay 74 is turned off, and the capacitor 48 and the U phase relay. 74u and the W phase of the three-phase AC power line are formed to determine whether or not an abnormality due to welding has occurred in the U-phase relay 74u. Thereafter, only the transistors T12 and T16 of the inverter 34 are connected. The capacitor 48, the V-phase relay 74v, and the three-phase AC power line are turned on for a predetermined time. W phase and may as to determine whether an abnormality by welding in a closed circuit is formed by V-phase relay 74v occurs including. In this case, when an abnormality due to welding occurs in the motor relay 74, it is possible to identify which of the U-phase relay 74u and the V-phase relay 74v has abnormality due to welding.

  In the embodiment, the present invention is applied to the electric vehicle 20 including the motor 32 that can input and output power to the drive shaft 22 connected to the drive wheels 26a and 26b and the inverter 34 for driving the motor 32. As illustrated in the hybrid vehicle 120 of the modified example of FIG. 5, an engine 122 and a motor 124 connected to the drive shaft 22 via a planetary gear mechanism 126, a motor 32 capable of inputting and outputting power to the drive shaft 22, It is good also as what applies to the hybrid vehicle 120 provided with. In this case, motor relays 74a and 74b can be attached to the motors 124 and 32, respectively. 6, the motor 32 is attached to the drive shaft 22 and the engine 122 is connected to the rotation shaft of the motor 32 via the clutch 229 as illustrated in the modified hybrid vehicle 220 of FIG. The present invention may be applied to a hybrid vehicle 220 that outputs power to the drive shaft 22 via the rotating shaft of the motor 32 and outputs power from the motor 32 to the drive shaft 22.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the battery 36 corresponds to a “DC power supply”, the motor 32 corresponds to a “three-phase AC motor”, the inverter 34 corresponds to an “inverter circuit”, the capacitor 48 corresponds to a “smoothing capacitor”, The system main relay 72 corresponds to the “power supply relay”, the motor relay 74 corresponds to the “motor relay”, and the electronic control unit 50 that executes the end processing routine of FIG. 4 corresponds to the “abnormality determination means”. .

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the power supply device manufacturing industry.

  20 electric vehicle, 22 drive shaft, 24 differential gear, 26 battery, 26a, 26b drive wheel, 32 motor, 32a rotational position detection sensor, 34 inverter, 36 battery, 40 boost converter, 42 battery voltage system power line, 44 high voltage System power line, 46 capacitor, 46a voltage sensor, 48 capacitor, 48a voltage sensor, 50 electronic control unit, 52 CPU, 54 ROM, 56 RAM, 60 ignition switch, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake pedal position sensor, 68 Vehicle speed sensor, 72 System main relay, 72a Positive side relay, 72b Negative side relay, 7 c Precharge Relay, 74, 74a, 74b Motor Relay, 74u U Phase Relay, 74v V Phase Relay, 120, 220 Hybrid Vehicle, 122 Engine, 124 Motor, 126 Planetary Gear Mechanism, 229 Clutch, D11 to D16, D31 , D32 Diode, L reactor, T11 to T16, T31, T32 transistors.

Claims (1)

A DC power supply, an inverter circuit that converts DC power from the DC power supply into three-phase AC power and supplies it to a three-phase AC motor, a smoothing capacitor connected between terminals on the DC power supply side of the inverter circuit, A power supply device mounted on a vehicle together with the three-phase AC motor,
A relay for power supply as a pair of relays attached to a positive power line and a negative power line in a direct current power line between the direct current power source and the inverter circuit;
A relay for the motor as a pair of relays attached to any two-phase power line of the three-phase power line between the inverter circuit and the three-phase AC motor;
When the ignition is turned off, the smoothing capacitor, the motor relay, and the three-phase power are turned off with the motor relay turned off after the power supply relay is turned off and before the voltage of the smoothing capacitor is discharged. When the closed circuit including a power line to which the motor relay is not attached is formed and the voltage of the smoothing capacitor drops more than a predetermined voltage before and after forming the closed circuit, the motor included in the closed circuit An abnormality determining means for determining that an abnormality has occurred due to welding of the relay;
A power supply device comprising:

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