Electric power source system

Abstract

To provide technique enabling proper output of an alarm related to a DC / DC converter and an alternator in a hybrid vehicle.SOLUTION: In an electric power source system 1 mounted in a hybrid vehicle, a DC / DC converter 24 converts the output voltage of a drive battery 18 of the hybrid vehicle and supplies the converted voltage to an auxiliary load 16. An alternator 12 is driven by the engine 10 of the hybrid vehicle to generate electric power and supplies the generated electric power to the auxiliary load 16. The output part 32 outputs an alarm related to the DC / DC converter 24 and the alternator 12 to an occupant of the hybrid vehicle. The output part 32 outputs a first alarm 1 urging stop when both the DC / DC converter 24 and the alternator 12 are abnormal and outputs a second alarm different from the first alarm when either one of the DC / DC converter 24 and the alternator 12 is abnormal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply system mounted on a hybrid vehicle. [Background technology]

[0002] In recent years, as the power consumption of auxiliary loads in hybrid vehicles has increased, there is a possibility that the power supply will be insufficient if only power is supplied to the auxiliary loads from the drive battery via a DC / DC converter. Therefore, by adding an alternator and supplying the generated power of the alternator to the auxiliary loads, the power supply shortage can be resolved. Patent Document 1 discloses a vehicle power supply system that includes a high-voltage battery, a DC / DC converter that supplies power to the auxiliary loads, and an engine-driven alternator connected in parallel with the DC / DC converter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Application No. 2023-041551 Specification Summary of the Invention [Problem to be solved by the invention]

[0004] In the power supply system described above, if an abnormality occurs in at least one of the DC / DC converter and the alternator, it is desirable to notify the occupants appropriately.

[0005] An object of the present invention is to provide a technique that can appropriately output a warning regarding a DC / DC converter and an alternator in a hybrid vehicle. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention provides a power supply system mounted on a hybrid vehicle, the power supply system including: a DC / DC converter that converts the output voltage of a drive battery of the hybrid vehicle and supplies the converted voltage to an auxiliary load; an alternator that is driven by an engine of the hybrid vehicle to generate power and supplies the generated power to the auxiliary load; and an output unit that outputs warnings regarding the DC / DC converter and the alternator to an occupant of the hybrid vehicle. If both the DC / DC converter and the alternator are abnormal, the output unit outputs a first warning urging the vehicle to stop, and if either the DC / DC converter or the alternator is abnormal, the output unit outputs a second warning different from the first warning. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technique for appropriately outputting warnings regarding a DC / DC converter and an alternator in a hybrid vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic functional configuration of a power supply system according to an embodiment. [Figure 2] 10 is a flowchart showing a warning output process in the power supply system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 shows a schematic functional configuration of a power supply system 1 according to an embodiment. The power supply system 1 is mounted on a hybrid electric vehicle (HEV) (not shown). Hereinafter, the hybrid vehicle will be simply referred to as a vehicle. The power supply system 1 may also be mounted on a plug-in hybrid electric vehicle (PHEV).

[0010] The power supply system 1 includes an engine 10, an alternator 12, an auxiliary battery 14, an auxiliary load 16, a drive battery 18, a power conversion unit 20, a motor 22, a DC / DC converter 24, a current sensor 26, an HEV control device 28, an engine control device 30, and an output unit 32. The alternator 12, the auxiliary battery 14, the drive battery 18, and the DC / DC converter 24 can also be called an auxiliary power supply. The drive battery 18, the power conversion unit 20, the motor 22, the DC / DC converter 24, and the HEV control device 28 can also be called an HEV system.

[0011] The vehicle runs using driving force from at least one of the engine 10 and the motor 22 .

[0012] The engine 10 is an internal combustion engine, and is started, its driving force is controlled, and it is stopped under the control of the engine control device 30. The driving force of the engine 10 is transmitted to an alternator 12. The driving force of the engine 10 can also be transmitted to drive wheels (not shown).

[0013] The alternator 12 is driven by the engine 10 to generate electric power and supplies the generated DC power to the auxiliary battery 14 and the auxiliary load 16 via the power supply line L1. The alternator 12 controls the output voltage so that the output voltage approaches the voltage indicated by the first power generation voltage instruction V1 from the engine control device 30.

[0014] The alternator 12 outputs first power generation state information S1 to the engine control device 30. The first power generation state information S1 is information relating to the operating state of the alternator 12. The information relating to the operating state of the alternator 12 is information for determining whether the alternator 12 is normal or abnormal, and includes, for example, information on the rotation speed of the rotor of the alternator 12, the internal voltage of the alternator 12, or the output current of the alternator 12. The internal voltage is a voltage that may differ from the output voltage of the output terminal of the alternator 12 connected to the power supply line L1, and is a voltage that allows detection of a fault in the alternator 12, such as a ground fault.

[0015] The auxiliary battery 14 is a secondary battery that can be charged and discharged. The auxiliary battery 14 has a lower voltage than the drive battery 18. The auxiliary battery 14 can supply power to the auxiliary load 16. The auxiliary battery 14 can be charged by at least one of the power generated by the alternator 12 and the power of the drive battery 18 supplied via the DC / DC converter 24.

[0016] The auxiliary load 16 is a load such as an electronic device provided in the vehicle. The auxiliary load 16 may include, for example, a headlamp, a navigation device, an audio device, an advanced driver assistance system, various ECUs, etc. The auxiliary load 16 may include an HEV control device 28, an engine control device 30, and an output unit 32. The auxiliary load 16 can operate using at least one of the power generated by the alternator 12, the power of the drive battery 18, and the power of the auxiliary battery 14.

[0017] The driving battery 18 is a rechargeable secondary battery such as a lithium ion battery, and can supply power to the power conversion unit 20 and the DC / DC converter 24.

[0018] The power conversion unit 20 includes an inverter and the like, converts the power of the drive battery 18, and supplies the converted power to the motor 22. The motor 22 generates driving force using the output power of the power conversion unit 20. The driving force of the motor 22 is transmitted to the drive wheels.

[0019] The input terminal of the DC / DC converter 24 is connected to the drive battery 18. The output terminal of the DC / DC converter 24 is connected to the alternator 12, the auxiliary battery 14, and the auxiliary load 16 via the power supply line L1. The DC / DC converter 24 is capable of supplying power from the drive battery 18 to the auxiliary battery 14 and the auxiliary load 16. The DC / DC converter 24 reduces the output voltage of the drive battery 18 so that it approaches a voltage indicated by a second power generation voltage command V2 from the HEV control device 28, and outputs the reduced voltage to the auxiliary load 16, etc. The second power generation voltage command V2 can also be called a voltage command value.

[0020] The DC / DC converter 24 outputs second power generation state information S2 to the HEV control device 28. The HEV control device 28 supplies the received second power generation state information S2 to the engine control device 30. The second power generation state information S2 is information related to the operating state of the DC / DC converter 24. The information related to the operating state of the DC / DC converter 24 is information for determining whether the DC / DC converter 24 is normal or abnormal, and includes, for example, information about the internal voltage or output current of the DC / DC converter 24. The internal voltage is a voltage that may differ from the output voltage of the output terminal of the DC / DC converter 24 connected to the power supply line L1, and is a voltage that allows detection of a fault in the DC / DC converter 24, such as a ground fault.

[0021] The current sensor 26 detects the output current I1 of the auxiliary battery 14 and supplies the detected output current I1 to the engine control device 30. The output current I1 of the auxiliary battery 14 is a current flowing from the auxiliary battery 14 to the auxiliary load 16.

[0022] The HEV control device 28 switches the vehicle's driving mode between a first driving mode and a second driving mode based on various signals supplied from various on-board sensors (not shown). The HEV control device 28 controls switching between the first driving mode, in which the motor 22 generates vehicle driving force using power supplied from the drive battery 18 and the engine 10 is stopped, and the second driving mode, in which the motor 22 and the engine 10 each generate vehicle driving force. The first driving mode can also be called an EV mode. The second driving mode can also be called an HV mode. The HEV control device 28 transmits control instructions related to the engine 10 to the engine control device 30. The engine control device 30 controls the operation of the engine 10 in accordance with the received instructions. Various known control methods can be used for controlling the first driving mode, the second driving mode, and switching between the first and second driving modes.

[0023] The engine control device 30 has a first determination unit 40, a second determination unit 42, an output control unit 44, and an engine control unit 46. The functional configurations of the HEV control device 28 and the engine control device 30 can be realized by the cooperation of hardware resources and software resources. The HEV control device 28 and the engine control device 30 each have hardware resources such as a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The ROM stores software resources such as various control programs and maps referenced when executing these various control programs. The CPU executes calculations based on the various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results from the CPU, data input from each sensor, and the like. The HEV control device 28 can be configured, for example, by an HEV-ECU (Electronic Control Unit). The engine control device 30 can be configured, for example, by an engine ECU.

[0024] The HEV control device 28 and the engine control device 30 coordinately control the engine 10, the alternator 12, and the DC / DC converter 24 based on the output current of the DC / DC converter 24 detected by a current sensor (not shown), and control the power supply to the auxiliary load 16.

[0025] For example, the HEV control device 28 sends a second power generation voltage command V2 to the DC / DC converter 24, causing the DC / DC converter 24 to output power. If the current consumption of the auxiliary load 16 is relatively small and the output current of the DC / DC converter 24 is smaller than a predetermined set value, the HEV control device 28 does not send a power generation command to the engine control device 30. As a result, the alternator 12 does not generate power, and the output power of the DC / DC converter 24 is supplied to the auxiliary load 16. The set value can be determined as appropriate through experiments or simulations.

[0026] When the current consumption of the auxiliary load 16 becomes relatively large and the output current of the DC / DC converter 24 reaches a set value, the HEV control device 28 sends a power generation command to the engine control device 30. In the engine control device 30, the engine control section 46 starts the engine 10 if it is not operating in response to the received power generation command, and sends a first power generation voltage command V1 to the alternator 12 to cause the alternator 12 to generate power. As a result, the output power of the DC / DC converter 24 and the output power of the alternator 12 are supplied to the auxiliary load 16, allowing the auxiliary load 16, which has a relatively large power consumption, to operate.

[0027] The auxiliary battery 14 can also supply power to the auxiliary load 16, but the output current of the auxiliary battery 14 is configured to be maintained below a predetermined current threshold. The current threshold is, for example, sufficiently smaller than the upper limit of the output current of the DC / DC converter 24 and sufficiently smaller than the upper limit of the output current of the alternator 12. The current threshold can be determined as appropriate through experiments or simulations.

[0028] The HEV control device 28 and the engine control device 30 may control the power supply to the auxiliary load 16 by the alternator 12 and the DC / DC converter 24 using other known control methods.

[0029] The engine control device 30 performs arbitration processing based on the output current I1 of the auxiliary battery 14, the first power generation state information S1, and the second power generation state information S2, and determines whether or not a warning is necessary regarding the DC / DC converter 24 and the alternator 12, and the content of the warning.

[0030] The first determination unit 40 determines whether the alternator 12 is normal or abnormal based on the first power generation state information S1 received from the alternator 12, i.e., information regarding the operating state of the alternator 12, and supplies the determination result to the output control unit 44. For example, the first determination unit 40 acquires the rotation speed of the engine 10 and determines that the alternator 12 is abnormal if the rotation speed of the rotor of the alternator 12 is lower than the rotation speed of the engine 10. The first determination unit 40 may determine that the alternator 12 is abnormal if the internal voltage of the alternator 12 is not within a predetermined first voltage range that includes the voltage indicated by the first power generation voltage command V1. The first voltage range may be determined appropriately through experiments or simulations. The first determination unit 40 may determine whether the alternator 12 is abnormal based on the output current of the alternator 12. Various known techniques may be used to determine whether the alternator 12 is abnormal.

[0031] The second determination unit 42 determines whether the DC / DC converter 24 is normal or abnormal based on the second power generation state information S2 received from the HEV control device 28, i.e., information regarding the operating state of the DC / DC converter 24, and supplies the determination result to the output control unit 44. For example, the second determination unit 42 may determine that the DC / DC converter 24 is abnormal if the internal voltage of the DC / DC converter 24 is not within a predetermined second voltage range that includes the voltage indicated by the second power generation voltage command V2. The second voltage range may be determined appropriately through experiments or simulations. The second determination unit 42 may also determine whether the DC / DC converter 24 is abnormal based on the output current of the DC / DC converter 24. Various known techniques may be used to determine whether the DC / DC converter 24 is abnormal.

[0032] The first determination unit 40 may be provided in the alternator 12 instead of in the engine control device 30. In this case, the first determination unit 40 may acquire information on the operating state of the alternator 12 and make the above-described determination. The alternator 12 may output, as the first power generation state information S1, information indicating whether the alternator 12 is normal or abnormal, which is the determination result by the first determination unit 40, to the engine control device 30.

[0033] Furthermore, second determination unit 42 may be provided in DC / DC converter 24 instead of in engine control unit 30. In this case, second determination unit 42 may acquire information relating to the operating state of DC / DC converter 24 and make the above-described determination. DC / DC converter 24 may output, as second power generation state information S2, information indicating whether DC / DC converter 24 is normal or abnormal, which is the determination result by second determination unit 42, to HEV control device 28.

[0034] The output control unit 44 compares the output current I1 of the auxiliary battery 14 with the aforementioned current threshold value, and if the output current I1 of the auxiliary battery 14 is equal to or greater than the current threshold value, sends a first output command to the output unit 32. If the output current I1 of the auxiliary battery is equal to or greater than the current threshold value, it is assumed that neither the output power of the DC / DC converter 24 nor the alternator 12 is being supplied to the auxiliary load 16, and that the current consumption of the auxiliary load 16 is relatively large.

[0035] The output current I1 of the auxiliary battery 14 being equal to or greater than the current threshold corresponds to a power balance deficit of a certain value or greater in the auxiliary load 16. The power balance in the auxiliary load 16 is the value obtained by subtracting the power consumed by the auxiliary load 16 from the power supplied to the auxiliary load 16 from the DC / DC converter 24 and the alternator 12.

[0036] Note that output control unit 44 may compare the voltage of power supply line L1 detected by a voltage sensor (not shown) with a predetermined voltage threshold instead of the output current I1 of auxiliary battery 14, and may send a first output instruction to output unit 32 when the voltage of power supply line L1 is equal to or lower than the voltage threshold. The voltage threshold is set so that when output current I1 of auxiliary battery 14 is equal to or higher than the current threshold, the voltage of power supply line L1 is equal to or lower than the voltage threshold.

[0037] Alternatively, the output control unit 44 may compare the SOC (State Of Charge) of the auxiliary battery 14, acquired by a known method, with a predetermined SOC threshold value instead of the output current I1 of the auxiliary battery 14, and may send a first output instruction to the output unit 32 when the SOC of the auxiliary battery 14 is equal to or lower than the SOC threshold value. The SOC threshold value is set so that the SOC of the auxiliary battery 14 is equal to or lower than the SOC threshold value when the output current I1 of the auxiliary battery 14 is equal to or higher than the current threshold value.

[0038] If the output current I1 of the auxiliary battery 14 is less than the current threshold, and the first judgment unit 40 and the second judgment unit 42 judge that both the DC / DC converter 24 and the alternator 12 are abnormal, the output control unit 44 sends a first output instruction to the output unit 32.

[0039] If the output current I1 of the auxiliary battery 14 is less than the current threshold, and the first judgment unit 40 and the second judgment unit 42 judge that either the DC / DC converter 24 or the alternator 12 is abnormal, the output control unit 44 sends a second output instruction to the output unit 32.

[0040] When the output current I1 of the auxiliary battery 14 is less than the current threshold, the output control unit 44 does not send an output instruction if the first judgment unit 40 and the second judgment unit 42 judge that both the DC / DC converter 24 and the alternator 12 are normal.

[0041] If it is determined that the DC / DC converter 24 is abnormal and the alternator 12 is normal, the engine control unit 46 causes the engine 10 to continue generating driving force and the alternator 12 to generate electricity. The driving force of the engine 10 is also transmitted to the drive wheels. The engine control unit 46 determines the fuel injection amount for the engine 10, for example, from the depression amount of an accelerator pedal (not shown) and the vehicle speed. If the DC / DC converter 24 is abnormal and the alternator 12 is normal, and the start switch is on, the engine control unit 46 causes the engine 10 to continue generating driving force even when the vehicle is stopped.

[0042] This allows the alternator 12 to generate electricity using the driving force of the engine 10, and the generated electricity can be supplied to the auxiliary load 16. Therefore, the auxiliary load 16 necessary for driving can continue to operate. If it is determined that the DC / DC converter 24 is abnormal, there is a possibility that the motor 22 cannot generate driving force due to an abnormality in the power conversion unit 20 of the HEV system, but the vehicle can still run using the driving force generated by the engine 10. Furthermore, even if the HEV system fails, the engine control device 30 continues to operate, so the engine 10 can be controlled.

[0043] When the DC / DC converter 24 is normal and the alternator 12 is abnormal, the engine control unit 46 controls the engine 10 in accordance with instructions from the HEV control device 28. That is, in this case, the vehicle can travel by switching between the first and second traveling modes, just as when both the DC / DC converter 24 and the alternator 12 are normal. Although the alternator 12 cannot generate power, the DC / DC converter 24 can supply power to the auxiliary load 16. Therefore, the auxiliary load 16 required for traveling can continue to operate.

[0044] The output unit 32 includes, for example, a multi-information display (MID), which is a display unit provided on an instrument panel, and provides various types of information to vehicle occupants. Upon receiving an output instruction from the output control unit 44, the output unit 32 outputs a warning regarding an abnormality in the DC / DC converter 24 and the alternator 12 to the vehicle occupants by display. The display includes, for example, a warning light and text representing a message. The output unit 32 may also output the warning by sound.

[0045] When the output unit 32 receives a first output instruction from the output control unit 44, it outputs a first warning urging the driver to stop the vehicle. That is, the output unit 32 outputs the first warning when the output current I1 of the auxiliary battery 14 is equal to or greater than the current threshold, or when the output current I1 is less than the current threshold and it is determined that both the DC / DC converter 24 and the alternator 12 are abnormal. The first warning includes, for example, a message urging the driver to stop the vehicle. The first warning may also include the display of a warning light indicating that both the DC / DC converter 24 and the alternator 12 are abnormal.

[0046] The first warning notifies the occupants that an abnormality has occurred and that the vehicle must be stopped before continuing to travel. In this case, if the vehicle continues to travel, the auxiliary battery 14 will continue to discharge, and when the power stored in the auxiliary battery 14 is substantially depleted, the auxiliary load 16 will stop operating and the vehicle will no longer be able to continue traveling.

[0047] In addition, the first warning is output when the output current I1 of the auxiliary battery 14 is equal to or greater than the current threshold value, so that the first warning can be output appropriately even if a failure occurs that is not determined to be an abnormality by the first judgment unit 40 and the second judgment unit 42.

[0048] When the output unit 32 receives a second output instruction from the output control unit 44, it outputs a second warning that is different from the first warning. That is, the output unit 32 outputs the second warning when it is determined that the output current I1 of the auxiliary battery 14 is less than the current threshold and that either the DC / DC converter 24 or the alternator 12 is abnormal. The second warning may include, for example, a message urging the customer to have the vehicle inspected or repaired at a dealership. The second warning may also include the display of a warning light indicating that either the DC / DC converter 24 or the alternator 12 is abnormal.

[0049] If either the DC / DC converter 24 or the alternator 12 is abnormal, a second warning different from the first warning that urges the driver to stop the vehicle is output, thereby informing the driver that an abnormality has occurred but that the vehicle can continue to be driven. The second warning message can also inform the driver that the vehicle needs to be inspected or repaired. This allows the driver to continue driving the vehicle, which is convenient. The driver can also drive the vehicle to a dealer or other facility.

[0050] In this case, the vehicle can continue to run because either the DC / DC converter 24 or the alternator 12, whichever is functioning properly, can supply power to the auxiliary load 16. However, for example, if the state in which the auxiliary load 16 consumes relatively large amounts of power continues for a long period of time, the auxiliary battery 14 may discharge further, and the auxiliary load 16 may become unable to operate.

[0051] If the output unit 32 does not receive an output instruction from the output control unit 44, that is, if it is determined that the output current I1 of the auxiliary battery 14 is less than the current threshold and both the DC / DC converter 24 and the alternator 12 are normal, the output unit 32 does not output a warning.

[0052] Here, a comparative power supply system recognized by the present inventor will be described. In the comparative example, even if either the DC / DC converter or the alternator is abnormal, the output unit outputs a first warning urging the driver to stop the vehicle. Therefore, even if either the DC / DC converter or the alternator is abnormal and the vehicle is in a state where it can continue to run, the driver ends up stopping the vehicle. In contrast, according to the embodiment, the driver can continue to run the vehicle as described above.

[0053] Next, a description will be given of the overall operation of the power supply system 1 configured as described above. Figure 2 is a flowchart showing the warning output process in the power supply system 1 of Figure 1. The process of Figure 2 is executed repeatedly.

[0054] If the output current of the auxiliary battery 14 is equal to or greater than the current threshold value (Y in S10), the output unit 32 outputs a first warning to prompt the driver to stop the vehicle (S12), and the process ends. If the output current of the auxiliary battery 14 is less than the current threshold value (N in S10), the DC / DC converter 24 is abnormal (Y in S14), or the alternator 12 is abnormal (Y in S16), the process proceeds to S12.

[0055] If the alternator 12 is not abnormal in S16 (N in S16), the output unit 32 outputs a second warning prompting inspection or repair (S20), and the process ends. If the DC / DC converter 24 is not abnormal in S14 (N in S14), and the alternator 12 is abnormal (Y in S18), the process proceeds to S20. If the alternator 12 is not abnormal in S18 (N in S18), the process ends.

[0056] According to the embodiment, warnings regarding the DC / DC converter 24 and the alternator 12 can be appropriately output in a hybrid vehicle.

[0057] The present invention has been described above based on the embodiments. However, the embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0058] 1...power supply system, 10...engine, 12...alternator, 14...auxiliary battery, 16...auxiliary load, 18...driving battery, 20...power conversion unit, 22...motor, 24...DC / DC converter, 26...current sensor, 28...HEV control device, 30...engine control device, 32...output unit, 40...first determination unit, 42...second determination unit, 44...output control unit, 46...engine control unit.

Claims

1. A power supply system mounted on a hybrid vehicle, a DC / DC converter that converts an output voltage of a drive battery of the hybrid vehicle and supplies the converted voltage to an auxiliary load; an alternator that is driven by an engine of the hybrid vehicle to generate electricity and supplies the generated electricity to the auxiliary load; an output unit that outputs a warning regarding the DC / DC converter and the alternator to a passenger of the hybrid vehicle, The output unit If both the DC / DC converter and the alternator are abnormal, a first warning is output to prompt the driver to stop the vehicle; When either the DC / DC converter or the alternator is abnormal, a second warning different from the first warning is output. A power supply system characterized by:

2. the second warning includes a message prompting inspection or repair of the hybrid vehicle; 2. The power supply system according to claim 1.

3. an auxiliary battery that supplies power to the auxiliary load; a first determination unit that determines whether the DC / DC converter is abnormal based on information about the operating state of the DC / DC converter; a second determination unit that determines whether the alternator is abnormal based on information about the operating state of the alternator, The output unit outputting the first warning when the current flowing from the auxiliary battery to the auxiliary load is equal to or greater than a threshold value; When the current is less than the threshold value, if it is determined that both the DC / DC converter and the alternator are abnormal, the first warning is output, if it is determined that either the DC / DC converter or the alternator is abnormal, the second warning is output, and if it is determined that both the DC / DC converter and the alternator are normal, no warning is output.

3. The power supply system according to claim 1 or 2.

4. an engine control unit that causes the engine to continue generating driving force and the alternator to generate electricity when the DC / DC converter is abnormal and the alternator is normal; The driving force of the engine is also transmitted to the drive wheels.

3. The power supply system according to claim 1 or 2.

5. When the DC / DC converter is abnormal and the alternator is normal, the engine control unit causes the engine to continue generating driving force even when the hybrid vehicle is stopped.

5. The power supply system according to claim 4.

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