Power supply system

Abstract

A power supply system is provided. In a case where power supply from a battery (14) to a load is ended, a fuse detection section (30) performs fuse detection of a power supply contactor (22), and in a case where operation of an OBPS (18) is stopped, the fuse detection section (30) performs fuse detection of the power supply contactor (22) after a prescribed time elapses from the start of the operation of the OBPS (18). Accordingly, even after the power supply circuit is stopped, fuse detection of the contactor can be performed.

Description

Technical Field

[0001] This invention relates to a power supply system. Background Technology

[0002] In recent years, in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy, research and development have been carried out on the charging power supply of vehicles equipped with secondary batteries that help improve energy efficiency.

[0003] Japanese Patent Publication No. 2014-193082 discloses an electric vehicle that provides power for charging. In this electric vehicle, the welding of the contactor between the charging port connected to an external load and the secondary battery is detected. Summary of the Invention

[0004] The technology disclosed in Japanese Patent Publication No. 2014-193082 has the following technical problem: when the power supply circuit stops during the power supply process, the contactor's welding cannot be detected.

[0005] The purpose of this invention is to solve the above-mentioned technical problems.

[0006] The present invention provides a power supply system for an electric vehicle. This power supply system includes a charging port, a battery, a charging circuit, a power supply circuit, an operation status acquisition unit, a contactor, a welding detection unit, and a charging / power supply prohibition control unit. The charging port is connected to an external power source or an external load of the electric vehicle. The battery stores electricity. The charging circuit is located between the charging port and the battery, supplying power from the power source to the battery. The power supply circuit is located between the charging port and the battery, supplying power from the battery to the load. The operation status acquisition unit acquires the operation status of the power supply circuit. The contactor is located between the charging port and the battery. The electrical circuit switches between a conducting state (connecting the power supply circuit and the charging power supply port) and a disconnecting state (disconnecting the power supply circuit and the charging power supply port); the welding detection unit performs welding detection on the contactor to determine whether the contactor is welded; if the contactor is determined to be welded, the charging power supply prohibition control unit prohibits the charging of the battery and the supply of power to the load; when the supply of power from the battery to the load ends, the welding detection unit performs welding detection on the contactor; when the operation of the power supply circuit stops, the welding detection unit performs welding detection on the contactor after a predetermined time has elapsed since the operation of the power supply circuit stopped.

[0007] According to the present invention, the contactor welding can be detected even when the power supply circuit is stopped during power supply.

[0008] The above-described objectives, features, and advantages should be readily understood from the following description of the embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a circuit diagram of the power supply system.

[0010] Figure 2 This is a block diagram of the control device.

[0011] Figure 3 This is a flowchart illustrating the power supply control process performed in the control device.

[0012] Figure 4 This is a flowchart illustrating the power supply control process performed in the control device. Detailed Implementation

[0013] [First Embodiment] Figure 1 This is a circuit diagram of the power supply system 10 according to this embodiment. The power supply system 10 is mounted on an electric vehicle. The charging port 12 of the electric vehicle is connected to an external power source. The battery 14 is charged using power supplied from the external power source. An external load is connected to the charging port 12 of the electric vehicle. The load is operated by power supplied from the battery 14. The battery 14 is a secondary battery, specifically a lithium-ion battery. The battery 14 can also be used as a power source for the drive motor of the electric vehicle.

[0014] An on-board charger 16 (hereinafter referred to as OBC16) is provided between the charging power supply port 12 and the battery 14. The OBC16 includes an inverter, a transformer, etc. The OBC16 converts the AC power supplied from the power source into DC power and boosts it before outputting it to the battery 14. The OBC16 corresponds to the charging circuit of the present invention.

[0015] An on-board power supply 18 (hereinafter referred to as OBPS18) is provided in parallel with OBC16. OBPS18 includes an inverter, an X capacitor, a smoothing capacitor, etc. OBPS18 converts the DC power supplied from battery 14 into AC power and steps it down before outputting it to the charging power supply port 12. OBPS18 corresponds to the power supply circuit of this invention.

[0016] A battery contactor 20 is provided between OBC16 and battery 14, and between OBPS18 and battery 14. The battery contactor 20 switches between a conducting state where current flows and a cutting-off state where current flow is interrupted. The battery contactor 20 includes a contactor 20a provided on the positive terminal and a contactor 20b provided on the negative terminal.

[0017] A power supply contactor 22 is provided between OBPS18 and the charging power supply port 12. The power supply contactor 22 switches between a conducting state where current flows and a cutting-off state where current flow is interrupted. The power supply contactor 22 includes a contactor 22a provided on the voltage line and a contactor 22b provided on the neutral line. The power supply contactor 22 corresponds to the contactor of the present invention.

[0018] OBC16 is used when charging battery 14 from an external power source, and OBPS18 is used when supplying power from battery 14 to an external load. When battery 14 is charging, approximately 200V to 240V of power is input to OBC16. Conversely, when supplying power from battery 14, approximately 100V to 120V of power is output from OBPS18.

[0019] During charging, when power from an external source is input to OBPS18, a voltage exceeding the withstand voltage may be applied to the X capacitor of OBPS18. Additionally, during charging, when power from an external source is input to OBPS18, a surge current may flow into the smoothing capacitor of OBPS18, allowing a current exceeding the withstand current to flow in the IGBT (Insulated Gate Bipolar Transistor) of the inverter.

[0020] Therefore, when the power supply system 10 is charging, it disconnects the OBPS18 from the charging power supply port 12 through the power supply contactor 22.

[0021] The power supply system 10 has a control device 24. Figure 2 This is a block diagram of the control device 24. The control device 24 includes an operation status acquisition unit 26, a power supply circuit control unit 28, a welding detection unit 30, and a charging power supply prohibition control unit 32.

[0022] The operation status acquisition unit 26, the power supply circuit control unit 28, the welding detection unit 30, and the charging power supply prohibition control unit 32 are implemented, for example, by a processing circuit. The processing circuit is constructed, for example, by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Alternatively, the processing circuit may also be constructed by an electronic circuit containing discrete components.

[0023] Alternatively, the processing circuit may be composed of a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In this case, the processing circuit is implemented by the processor executing a program stored in a memory unit (not shown).

[0024] The operation status acquisition unit 26 acquires the drive signal of the inverter of OBPS18. The smaller the duty cycle of the drive signal, the greater the power output from OBPS18.

[0025] In cases (1) to (4) below, the duty cycle of the drive signal is 100%, and OBPS18 stops.

[0026] (1) When the output voltage of OBPS18 is low. (2) The voltage on the output side of OBPS18 is overvoltage. (3) OBPS18 is at a high temperature (4) OBPS18 malfunction.

[0027] The output side of OBPS18 refers to the side where OBPS18 is connected to the charging power supply port 12. The main reasons for a low output voltage on the OBPS18 are overload or short circuit in the external load. The main reasons for an overvoltage on the output side of OBPS18 are surge voltage applied from the external load. The main reasons for a high temperature on OBPS18 are continuous operation of OBPS18 in high-temperature environments. The main reasons for OBPS18 failure are abnormal sensors in the OBPS18 inverter or short circuits in the AC wiring connected to OBPS18.

[0028] In cases (1) to (3) above, OBPS18 recovers after a specified time. After recovery, the duty cycle of the drive signal in the inverter of OBPS18 is less than 100%. In case (4) above, OBPS18 does not recover, and the duty cycle of the drive signal remains at 100%. In case (4) above, the user can also be informed and urged to take the vehicle to a dealership for repair.

[0029] When the power supply switch 34 is turned on, power supply to the external load begins. When the power supply switch 34 is turned off, power supply to the external load ends. The power supply switch 34 is operated by the user of the electric vehicle.

[0030] The power supply circuit control unit 28 controls OBPS18 and power supply contactor 22 according to the signal from power supply switch 34.

[0031] The weld detection unit 30 performs weld detection on the power supply contactor 22. Weld detection unit 30 performs weld detection when the power supply switch 34 is operated to open and power supply is stopped. During power supply, when OBPS18 stops, weld detection unit 30 performs weld detection after a predetermined time has elapsed since OBPS18 stopped.

[0032] When performing weld detection, the weld detection unit 30 controls the OBPS18 via the power supply circuit control unit 28 to output power from the OBPS18. Additionally, the weld detection unit 30 controls the power supply contactor 22 via the power supply circuit control unit 28, ensuring that only one of contactors 22a and 22b is connected. In this state, if the voltage detected by the voltage sensor 36 installed on the OBC16 is above a predetermined value, the weld detection unit 30 determines that the power supply contactor 22 is welded. The weld detection unit 30 controls the power supply contactor 22, ensuring that only the other of contactors 22a and 22b is connected. In this state, if the voltage detected by the voltage sensor 36 installed on the OBC16 is above a predetermined value, the weld detection unit 30 determines that the power supply contactor 22 is welded.

[0033] In the following situations, the charging power supply prohibition control unit 32 prohibits charging of the battery 14 from an external power source and supplying power from the battery 14 to an external load: The following situations occur when the weld detection unit 30 determines that the power supply contactor 22 is welded, or when OBPS18 fails to recover after a predetermined time since stopping. In this case, the charging power supply prohibition control unit 32 stops OBC16 and OBPS18. Additionally, the charging power supply prohibition control unit 32 disconnects the battery contactor 20 and the power supply contactor 22.

[0034] Figure 3 and Figure 4 This is a flowchart illustrating the power supply control process executed in control device 24. The power supply control is repeatedly executed at a predetermined cycle.

[0035] In step S1, the power supply circuit control unit 28 determines whether the charging power supply prohibition flag is "0" or "1". If the charging power supply prohibition flag is "0", the process proceeds to step S2. If the charging power supply prohibition flag is "1", the power supply control ends.

[0036] In step S2, the power supply circuit control unit 28 determines whether the power supply stop flag is "0" or "1". If the power supply stop flag is "0", proceed to step S3. If the power supply stop flag is "1", proceed to step S13.

[0037] In step S3, the power supply circuit control unit 28 determines whether the signal of the power supply switch 34 has switched from off to on. If the signal of the power supply switch 34 has switched from off to on, the process proceeds to step S4. If the signal of the power supply switch 34 has not switched from off to on, the process proceeds to step S5. If the signal of the power supply switch 34 was off when power supply control was performed in the previous cycle, and the signal of the power supply switch 34 is on when power supply control is performed in the current cycle, it can be determined that the signal of the power supply switch 34 has switched from off to on.

[0038] In step S4, the power supply circuit control unit 28 outputs an output command to OBPS18 and power supply contactor 22. Then, the power supply control ends. According to the output command, power supply contactor 22 becomes conductive. According to the output command, OBPS18 operates.

[0039] In step S5, the power supply circuit control unit 28 determines whether the signal of the power supply switch 34 has switched from on to off. If the signal of the power supply switch 34 has switched from on to off, the process proceeds to step S9. If the signal of the power supply switch 34 has not switched from on to off, the process proceeds to step S6. If the signal of the power supply switch 34 was on when power supply control was performed in the previous cycle, and the signal of the power supply switch 34 is off when power supply control is performed in the current cycle, it can be determined that the signal of the power supply switch 34 has switched from on to off.

[0040] In step S6, the power supply circuit control unit 28 determines whether the signal of the power supply switch 34 is on or off. If the signal of the power supply switch 34 is on, the process proceeds to step S7. If the signal of the power supply switch 34 is off, the power supply control ends.

[0041] In step S7, the power supply circuit control unit 28 determines whether the duty cycle of the inverter drive signal in OBPS18 is 100% or less. If the duty cycle is 100%, the process proceeds to step S8. If the duty cycle is less than 100%, the power supply control ends. With the power supply switch 34 signal on, the power supply circuit control unit 28 monitors the operation of OBPS18 in each cycle of power supply control. If the duty cycle of the inverter drive signal is 100%, the power supply circuit control unit 28 determines that OBPS18 has stopped. If the duty cycle of the inverter drive signal is less than 100%, the power supply circuit control unit 28 can determine that OBPS18 has operated.

[0042] In step S8, the power supply circuit control unit 28 sets the power supply stop flag to "1". Then, the power supply control ends. A power supply stop flag of "1" indicates that OBPS18 is in the process of stopping.

[0043] When the power supply switch 34 is operated and the signal switches from on to off, in step S9, the weld detection unit 30 performs weld detection on the power supply contactor 22. After that, the process proceeds to step S10.

[0044] In step S10, the weld detection unit 30 determines whether the power supply contactor 22 is welded. If the power supply contactor 22 is welded, the process proceeds to step S11. If the power supply contactor 22 is not welded, the process proceeds to step S12.

[0045] In step S11, the charging and power supply prohibition control unit 32 sets the charging and power supply prohibition flag to "1". Then, the process proceeds to step S12. For example, if the electric vehicle is taken to a dealership or other facility for repairs to the power supply system 10, the charging and power supply prohibition flag is set to "0".

[0046] In step S12, the charging power supply prohibition control unit 32 outputs a charging power supply prohibition command. Afterwards, power supply control ends. According to the charging power supply prohibition command, battery contactor 20 and power supply contactor 22 are controlled to the disconnected state. According to the charging power supply prohibition command, OBC16 and OBPS18 stop.

[0047] When OBPS18 stops, in step S13, the power supply circuit control unit 28 calculates the elapsed time. The elapsed time represents the time from when OBPS18 stops until the processing of step S13 is performed. The power supply circuit control unit 28 can calculate the elapsed time by adding the elapsed time calculated in the previous cycle to the time of one cycle of power supply control each time step S13 is performed.

[0048] In step S14, the power supply circuit control unit 28 determines whether the elapsed time is more than or less than the predetermined time. If the elapsed time is more than the predetermined time, the process proceeds to step S15. If the elapsed time is less than the predetermined time, the power supply control ends.

[0049] If a predetermined time has elapsed since the OBPS18 stopped, in step S15, the weld detection unit 30 performs weld detection on the power supply contactor 22. Afterwards, the process proceeds to step S16.

[0050] In step S16, the power supply circuit control unit 28 determines whether the duty cycle of the inverter drive signal in OBPS18 is 100% or less. If the duty cycle is 100%, proceed to step S20. If the duty cycle is less than 100%, proceed to step S17.

[0051] In step S17, the power supply circuit control unit 28 sets the power supply stop flag to "0". Then, proceed to step S18.

[0052] In step S18, the weld detection unit 30 determines whether the power supply contactor 22 is welded. If the power supply contactor 22 is welded, the process proceeds to step S20. If the power supply contactor 22 is not welded, the process proceeds to step S19.

[0053] In step S19, the power supply circuit control unit 28 outputs an output command to OBPS18 and power supply contactor 22. Then, the power supply control ends. According to the output command, power supply contactor 22 becomes conductive. According to the output command, OBPS18 operates.

[0054] In step S20, the charging power supply prohibition control unit 32 sets the charging power supply prohibition flag to "1". Then, the process proceeds to step S21.

[0055] In step S21, the charging power supply prohibition control unit 32 outputs a charging power supply prohibition command. Afterwards, power supply control ends. According to the charging power supply prohibition command, battery contactor 20 and power supply contactor 22 are controlled to the disconnected state. According to the charging power supply prohibition command, OBC16 and OBPS18 stop.

[0056] [Effects] In cases (1) to (4), OBPS18 is stopped to protect it. During the stopping of OBPS18, the welding detection of the power supply contactor 22 cannot be performed. However, in cases (1) to (3), OBPS18 resumes operation after a specified time.

[0057] Therefore, in the power supply system 10 of this embodiment, the weld detection unit 30 performs weld detection after a predetermined time from when the OBPS 18 stops. This allows weld detection of the power supply contactor 22 to be performed even after the OBPS 18 has stopped. Furthermore, it further contributes to improved energy efficiency.

[0058] Furthermore, in the power supply system 10 of this embodiment, if OBPS18 fails to recover even after a predetermined time has elapsed since its operation stopped, the charging power supply prohibition control unit 32 prohibits charging of the battery 14 from an external power source and supplying power from the battery 14 to an external load. If OBPS18 fails to recover, it is determined that OBPS18 is faulty, and the charging power supply prohibition control unit 32 can prohibit charging of the battery 14 from an external power source and supplying power from the battery 14 to an external load.

[0059] Furthermore, the present invention is not limited to the embodiments described above, and various structures can be adopted without departing from the spirit of the present invention.

[0060] [Technical solutions that can be obtained according to the implementation method] The following describes the technical solutions that can be mastered based on the above-described embodiments.

[0061] A power supply system (10) for an electric vehicle includes a charging port (12), a battery (14), a charging circuit (16), a power supply circuit (18), an operation status acquisition unit (26), a contactor (22), a welding detection unit (30), and a charging power supply prohibition control unit (32). The charging port is connected to an external power source or an external load of the electric vehicle. The battery stores electricity. The charging circuit is located between the charging port and the battery, supplying power from the power source to the battery. The power supply circuit is located between the charging port and the battery, supplying power from the battery to the load. The operation status acquisition unit acquires the operation status of the power supply circuit. The contactor is positioned between the power supply circuit and the charging port, switching between a conducting state (connecting the power supply circuit and the charging port) and a disconnecting state (disconnecting the power supply circuit and the charging port). The welding detection unit detects welding of the contactor to determine if it is welded. If welding is detected, the charging power supply prohibition control unit prohibits charging the battery and supplying power to the load. When power supply from the battery to the load ceases, the welding detection unit detects welding of the contactor again. When the power supply circuit stops operating, the welding detection unit detects welding of the contactor after a predetermined time has elapsed since the power supply circuit stopped operating. Therefore, welding detection of the contactor can be performed even after the power supply circuit has stopped.

[0062] In the aforementioned power supply system, if the power supply circuit fails to recover after a predetermined time since its operation ceased, the charging power supply prohibition control unit may prohibit charging of the battery and supplying power to the load. Thus, if the power supply circuit fails to recover, a power supply circuit fault is determined, and charging power supply can be prohibited.

Claims

1. A power supply system (10), which is a power supply system for electric vehicles, characterized in that, It has a charging power supply port (12), a battery (14), a charging circuit (16), a power supply circuit (18), an operation status acquisition unit (26), a contactor (22), a welding detection unit (30), and a charging power supply prohibition control unit (32), wherein, The charging power supply port is connected to an external power source of the electric vehicle or an external load of the electric vehicle. The battery stores electricity; The charging circuit is located between the charging power supply port and the battery, and supplies power from the power source to the battery. The power supply circuit is located between the charging power port and the battery, and supplies the power of the battery to the load. The action status acquisition unit acquires the action status of the power supply circuit; The contactor is disposed between the power supply circuit and the charging power supply port, and switches between a conducting state that connects the power supply circuit and the charging power supply port and a disconnecting state that disconnects the power supply circuit and the charging power supply port. When power is output from the power supply circuit, the welding detection unit performs welding detection on the contactor and determines whether the contactor is welded. If the contactor is determined to be fused, the charging power supply prohibition control unit prohibits the charging of the battery and the supply of power to the load. If the operation of the power supply circuit stops during power supply, the welding detection unit performs welding detection on the contactor after a predetermined time required for the protection of the power supply circuit has elapsed since the stop and the power supply circuit has resumed operation.

2. The power supply system according to claim 1, characterized in that, If the operation of the power supply circuit stops during the power supply process and the power supply circuit does not resume after the specified time, the charging power supply prohibition control unit prohibits the charging of the battery and the supply of power to the load.

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