Multi-output power source control device, multi-output power source system, control method for multi-output power source control device, and program

Abstract

High-voltage (48 V) power source systems (ES4a, ES4b) are connected to a positive terminal (74) of a top battery cell of a battery pack (700), and low-voltage (12 V) power source systems (ES1a, ES1b) are connected to a positive terminal (71) of a battery cell of the battery pack (700) other than the top battery cell. Loads (84a, 84b, 81a, 81b) are respectively connected to the high-voltage power source systems and the low-voltage power source systems. A midpoint converter (40) is capable of interchanging power unidirectionally or bidirectionally between the high-voltage power source systems and the low-voltage power source systems. An inter-high-voltage-system switch (554) is provided between a power supply unit (10) and the positive terminal (74) of the top battery cell of the battery pack (700). A control unit (20) is capable of controlling output of the power supply unit (10) and the midpoint converter (40) and determining at least an abnormality in the high-voltage power source systems, and switches between on and off of the inter-high-voltage-system switch (554) on the basis of the determination result.

Description

Multi-output power supply control device, multi-output power supply system, control method for multi-output power supply control device, and program Cross-Reference to Related Applications

[0001] The present application is based on Japanese Application No. 2025-068009 filed on April 17, 2025, the contents of which are incorporated herein by reference in their entirety.

[0002] The present disclosure relates to a multi-output power supply control device, a multi-output power supply system, a control method for a multi-output power supply control device, and a program.

[0003] Conventionally, power supply devices capable of supplying power to loads respectively connected to a plurality of power supply systems with different voltages are known. For example, the power conversion and supply device disclosed in Patent Document 1 aims to stably supply a desired DC voltage without having two types of storage batteries. The configuration of this device is described in FIG. 14 as a comparative example.

[0004] In the device of the comparative example, a high-voltage auxiliary machine 4 is connected to the upper terminal 1d of the storage battery 1 connected in series, and a low-voltage auxiliary machine 6 is connected to the intermediate terminal 1c. The storage battery 1 is connected to and charged by a power supply unit (an alternator including a generator 3a driven by an engine 2 and a full-wave rectifier 3b) 3. As indicated by the bidirectional arrows, power can be transferred between the upper battery block 1b and the lower battery block 1a of the storage battery 1 via the DCDC converter 5.

[0005] Japanese Unexamined Patent Application Publication No. 2001-136735

[0006] In the device of the comparative example, as shown in FIG. 15, when the transistor TR2 of the DCDC converter 5 suffers a short-circuit failure, both the high-voltage current output from the upper terminal 1d of the storage battery 1 and the low-voltage current output from the intermediate terminal 1c of the storage battery 1 flow to the ground. As a result, power supply to the low-voltage auxiliary machine 6 is lost, leading to functional stoppage. In addition, as shown in FIG. 16, when the harness connected to the upper terminal 1d of the storage battery 1 suffers a ground fault, power supply to the high-voltage auxiliary machine 4 is lost, leading to functional stoppage.

[0007] As described above, with the prior art described in Patent Document 1, there is a concern that a failure of the DC-DC converter, a ground fault or disconnection of the harness may result in a loss of power supply to low-voltage or high-voltage auxiliary equipment, leading to the malfunction of the auxiliary equipment. For example, if an auxiliary equipment that controls functions related to autonomous driving or a load used as equipment for a drive-by-wire system in a vehicle's power supply system malfunctions, it will have a serious impact on driving performance.

[0008] The purpose of this disclosure is to provide a multi-output power control device and a multi-output power system that prevent all loads in at least a high-voltage power supply system from simultaneously failing to function. Furthermore, it is to provide a control method and program for the multi-output power control device.

[0009] In a multi-output power supply system to which the multi-output power supply control device described herein is applied, a high-voltage power supply system is connected to the positive terminal of the topmost battery cell of a battery pack in which multiple battery cells are connected in series, and one or more low-voltage power supply systems are connected to the positive terminals of one or more battery cells other than the topmost one of the battery pack. Loads are connected to both the high-voltage power supply system and the low-voltage power supply system. The power supply unit connected to the positive terminal of the topmost battery cell of the battery pack can charge the battery pack and supply power to the high-voltage power supply system.

[0010] The multi-output power control device comprises a midpoint converter, a high-voltage inter-system switch, and a control unit. The midpoint converter is capable of unidirectional or bidirectional power exchange between the high-voltage power system and the low-voltage power system. The high-voltage inter-system switch is provided between the power supply unit and the positive terminal of the uppermost battery cell of the battery pack. The control unit controls the outputs of the power supply unit and the midpoint converter, and is capable of determining at least an abnormality in the high-voltage power system, and switches the high-voltage inter-system switch ON / OFF based on the determination result.

[0011] The high-voltage inter-system switch divides the high-voltage power supply system into a first high-voltage power supply system connected to the battery pack side of the inter-system switch and a second high-voltage power supply system connected to the power supply unit side of the inter-system switch.

[0012] The multi-output power supply control device of this disclosure can prevent the fault from propagating to the other high-voltage power supply system when a power failure occurs in either the first or second high-voltage power supply system due to a failure of the midpoint converter or a ground fault in the harness, etc., by turning off the high-voltage system-to-system switch in the control unit. Furthermore, it can continue to function by supplying power from the power supply unit or battery pack to the normal high-voltage power supply system.

[0013] The multi-output power supply system according to this disclosure comprises the multi-output power supply control device described above, a battery pack in which multiple battery cells are connected in series, loads connected to a high-voltage power supply system and a low-voltage power supply system, respectively, and a power supply unit.

[0014] The high-voltage power supply system is connected to the positive terminal of the topmost battery cell of the battery pack. The low-voltage power supply system is connected to the positive terminal of one or more battery cells other than the topmost one of the battery pack. The power supply unit is connected to the positive terminal of the topmost battery cell of the battery pack and is capable of charging the battery pack and supplying power to the high-voltage power supply system.

[0015] Furthermore, this disclosure is also provided as a control method executed by a control unit in a multi-output power supply control device, and as a program that causes the control unit to perform a specific process in the multi-output power supply control device. Here, the multi-output power supply control device further comprises a midpoint converter and a low-voltage inter-system switch provided between the positive terminal of a battery cell to which a low-voltage power supply system is connected in a battery pack. The control unit is further capable of determining an abnormality in the low-voltage power supply system and switches the low-voltage inter-system switch ON / OFF based on the determination result.

[0016] The low-voltage inter-system switch divides the low-voltage power supply system into a first low-voltage power supply system connected to the battery pack side of the low-voltage inter-system switch and a second low-voltage power supply system connected to the midpoint converter side of the low-voltage inter-system switch.

[0017] The control unit determines abnormalities in the high-voltage power supply system and the low-voltage power supply system. When an abnormality occurs in the high-voltage power supply system, the control unit turns off the high-voltage system-to-system switch, and when an abnormality occurs in the low-voltage power supply system, it turns off the low-voltage system-to-system switch. This prevents fault propagation from the faulty power supply system to the normal power supply system, and allows power to be supplied to the normal power supply system.

[0018] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer with reference to the attached drawings and the detailed description below. The drawings are as follows: Figure 1 is an overall configuration diagram of the multi-output power supply system of the first embodiment; Figure 2 is a schematic configuration diagram of the multi-output power supply system of the first embodiment; Figure 3 is a diagram showing the operation in the event of a ground fault in the 48V first system; Figure 4 is a diagram showing the operation in the event of a ground fault in the 48V second system; Figure 5 is a diagram showing the operation in the event of a ground fault in the 12V first system; Figure 6 is a diagram showing the operation in the event of a ground fault in the 12V second system; Figure 7 is a diagram showing the state with both the 48V / 12V system switches turned OFF; and Figure 8 is a diagram showing the state with the overcurrent protection relay further turned OFF from the state in Figure 7. Figure 9 is a time chart for a 48V power supply abnormality corresponding to Figure 8, Figure 10 is a flowchart showing the processing of the control unit, Figure 11 is a schematic configuration diagram of the multi-output power supply system of the second embodiment, Figure 12 is a schematic configuration diagram of the multi-output power supply system of another embodiment, Figure 13 is a schematic configuration diagram of the multi-output power supply system of another embodiment, Figure 14 is a configuration diagram of the comparative example device, Figure 15 is a diagram illustrating the problems in the comparative example device when the DC-DC converter fails, and Figure 16 is a diagram illustrating the problems in the comparative example device when the harness ground fault fails.

[0019] Multiple embodiments of the multi-output power supply system and multi-output power supply control device described herein will be explained with reference to the drawings. The first and second embodiments are collectively referred to as "this embodiment." The multi-output power supply system of this embodiment is installed in an electric vehicle as a typical example of a "mobile body having multiple power supply systems, with loads connected to each power supply system." Conventionally, auxiliary loads for vehicles have generally used 12V power supplies, but in the future, auxiliary loads using 48V power supplies may be used in combination to accommodate autonomous driving and vehicle intelligence. Therefore, a multi-output power supply system is needed to supply power to two power supply systems, a 48V system and a 12V system, to which loads are connected.

[0020] (First Embodiment) Referring to Figure 1, the configuration of the multi-output power supply system 100 of the first embodiment will be described. The multi-output power supply system 100 includes a power supply unit 10, a multi-output power supply control device 200, a battery pack 700, and a plurality of loads 84a, 84b, 81a, and 81b. The 48V loads 84a and 84b are connected to the 48V systems ES4a and ES4b, which are "high-voltage power supply systems," and the 12V loads 81a and 81b are connected to the 12V systems ES1a and ES1b, which are "low-voltage power supply systems." Figure 1 shows one block each of the 48V loads 84a and 84b and the 12V loads 81a and 81b, but multiple 48V loads 84a and 84b and multiple 12V loads 81a and 81b may be connected to each.

[0021] Here, the 48V system, which is a "high-voltage power supply system," is divided into the 48V first system ES4a, which is a "high-voltage first power supply system," and the 48V second system ES4b, which is a "high-voltage second power supply system," by the 48V system switch 554, which is a "high-voltage system inter-system switch." The 12V system, which is a "low-voltage power supply system," is divided into the 12V first system ES1a, which is a "low-voltage first power supply system," and the 12V second system ES1b, which is a "low-voltage second power supply system," by the 12V system switch 551, which is a "low-voltage system inter-system switch."

[0022] Loads 84a, 84b, 81a, and 81b are broadly classified into specific loads used for vehicle driving assistance and general loads not used for vehicle driving assistance. Specific loads include the steering motor of the electric power steering system, electric brakes, monitoring cameras, laser radar such as LiDAR (rangefinder), millimeter-wave radar, and equipment for drive-by-wire systems. General loads include air conditioners, audio equipment, power windows, lamps, etc.

[0023] In particular, specific loads are redundantly provided in the first and second systems, as described in the blocks for each load 84a, 84b, 81a, and 81b. Even if one fails, the other function can continue due to the other working load, thus improving the reliability of the vehicle's driving performance. Examples of redundantly provided auxiliary equipment include steering motors composed of two winding systems. When functioning normally, both systems drive the motor, and when one system fails, the working system drives it, resulting in reduced output but preventing complete failure. Alternatively, a combination where one can replace the other, such as a monitoring camera and a laser radar, which perform similar functions of monitoring the surroundings of the vehicle, may also be used.

[0024] The power supply unit 10 of this embodiment includes a main battery 13 with several hundred volts, which is the driving power source for the vehicle, an auxiliary converter 14, and a controller 15. The auxiliary converter 14 is composed of an isolated DC-DC converter, with the primary coil connected to the main battery 13 and the secondary coil connected between the 48V output terminal and ground. The controller 15 controls the auxiliary converter 14 according to instructions from the control unit 20 of the multi-output power supply control device 200. In response to the control of the controller 15, the auxiliary converter 14 converts the power from the main battery 13 into 48V power and outputs it.

[0025] The battery pack 700 consists of multiple battery cells, for example, lithium-ion batteries, connected in series. The voltage of one battery cell is approximately 3V. Note that the number of battery cells in the diagram does not necessarily reflect the actual number. The multiple battery cells can be divided into two battery blocks, for example, the upper battery block 70U and the lower battery block 70L. Hereinafter, the positive terminal (positive electrode terminal) of the topmost battery cell in the upper battery block 70U (i.e., the topmost battery cell of the battery pack 700) will be referred to as the "upper terminal 74". The positive terminal of the topmost battery cell in the lower battery block 70L (i.e., one or more battery cells other than the topmost one in the battery pack 700) will be referred to as the "intermediate terminal 71".

[0026] The 48V lines ES4a and ES4b are connected to the upper terminal 74 of the battery pack 700. The 12V lines ES1a and ES1b are connected to the intermediate terminal 71 of the battery pack 700. The power supply unit 10 is capable of charging the battery pack 700 and supplying power to the 48V lines ES4a and ES4b.

[0027] The multi-output power control device 200 includes a midpoint converter 40, inter-system switches 554, 551, an overcurrent interruption relay 57, cell voltage detection units 66U, 66L, power system voltage detection units 654, 651, a relay current detection unit 67, a control unit 20, and the like. The multi-output power control device 200 is mounted on a circuit board, for example, and housed in a case together with the auxiliary converter 14, controller 15, and battery pack 700 of the power supply unit 10.

[0028] The midpoint converter 40, as an example of a circuit configuration, includes switching elements 43U, 43L, capacitors 44U, 44L, a coil 45, a controller 46, etc. The switching elements 43U and 43L are provided between the 48V output terminal of the auxiliary converter 14 and ground, with the midpoint Ns in between. The capacitors 44U and 44L are provided in parallel with the switching elements 43U and 43L, respectively, with the midpoint Nc connected to the intermediate terminal 71 of the battery pack 700 in between. The coil 45 is connected between the midpoint Ns and the midpoint Nc.

[0029] The controller 46 switches the switching elements 43U and 43L at a predetermined frequency according to instructions from the control unit 20. As a result, the coil 45 repeatedly stores and releases induced energy, converting power in either direction, from the 48V system ES4 to the 12V system ES1, or from the 12V system ES1 to the 48V system ES4. Therefore, the midpoint converter 40 can exchange power bidirectionally between the 48V system ES4 and the 12V system ES1 by boosting or stepping up the voltage.

[0030] The 48V inter-system switch 554, which is a "high-voltage inter-system switch," is installed between the power supply unit 10 and the upper terminal 74. The 48V inter-system switch 554 divides the 48V system into "a first 48V system ES4a connected to the battery pack 700 side of the 48V inter-system switch 554" and "a second 48V system ES4b connected to the power supply unit 10 side of the 48V inter-system switch 554." In other words, the 48V system is configured to be able to supply power to both sides of the 48V inter-system switch 554.

[0031] The 12V inter-system switch 551, which is a "low-voltage inter-system switch," is installed between the midpoint converter 40 and the intermediate terminal 71 of the battery pack 700 to which the 12V systems ES1a and ES1b are connected. The 12V inter-system switch 551 divides the 12V system into "the 12V first system ES1a connected to the battery pack 700 side of the 12V inter-system switch 551" and "the 12V second system ES1b connected to the midpoint converter 40 side of the 12V inter-system switch 551." In other words, the 12V system is configured to be able to supply power to both sides of the 12V inter-system switch 551.

[0032] The cell voltage detection units 66U and 66L detect the voltage of each battery cell. Specifically, the cell voltage detection unit 66U detects the single cell voltage Vcell_U of the upper battery block. The cell voltage detection unit 66L detects the single cell voltage Vcell_L of the lower battery block.

[0033] The power supply system voltage detection units 654 and 651 detect the voltages of the 48V systems ES4a and ES4b and the 12V systems ES1a and ES1b, respectively. Specifically, the 48V system voltage detection unit 654 detects the voltage Vs48 of the 48V systems ES4a and ES4b at the upper terminal 74, for example. The 12V system voltage detection unit 651 detects the voltage Vs12 of the 12V systems ES1a and ES1b at the intermediate terminal 71, for example. Details of the overcurrent interruption relay 57 and the relay current detection unit 67 will be described later with reference to Figures 8 to 10. The relay current detection unit 67 detects the relay current I_Ry flowing through the overcurrent interruption relay 57.

[0034] The control unit 20 internally includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (not shown). The control unit 20 performs software processing by executing pre-stored programs on the CPU, and control through hardware processing using dedicated electronic circuits.

[0035] The control unit 20 of this embodiment includes a power supply instruction unit 22 and a power supply abnormality determination unit 26. Hereinafter, "upper battery block and lower battery block" will be appropriately referred to as "upper / lower battery block". The power supply instruction unit 22 calculates the State of Control (SOC) of each battery cell based on the upper / lower battery block single cell voltages Vcell_U and Vcell_L. The power supply instruction unit 22 then controls the output of the power supply unit 10 and the midpoint converter 40 by instructing the controller 15 of the power supply unit 10 and the controller 46 of the midpoint converter 40 so that the SOC of each battery cell reaches a predetermined target value.

[0036] The power supply abnormality determination unit 26 determines an abnormality in each power supply system based on the 48V system voltage Vs48 and 12V system voltage Vs12 detected by the power supply system voltage detection units 654 and 651, and the relay current I_Ry detected by the relay current detection unit 67. Based on the determination result, the power supply abnormality determination unit 26 switches the 48V system switch 554 and the 12V system switch 551 ON / OFF.

[0037] During normal operation, the multi-output power control device 200 adjusts the power output from the power supply unit 10 and the midpoint converter 40, and supplies power to both the 48V systems ES4a, ES4b and the 12V systems ES1a, ES1b while controlling the state of charge (SOC) of the battery cells in the upper battery block 70U and the lower battery block 70L to the target value. During normal operation, both the 48V system switch 554 and the 12V system switch 551 are in the ON state.

[0038] If a ground fault occurs in any of the 48V first system ES4a, 48V second system ES4b, 12V first system ES1a, or 12V second system ES1b, the power supply abnormality determination unit 26 of the control unit 20 determines that there is a power supply abnormality and turns OFF at least one of the 48V system-to-system switch 554 or the 12V system-to-system switch 551. Depending on the location of the power supply abnormality, the power supply device instruction unit 22 can instruct the system to continue supplying power to a normal power supply system.

[0039] Figure 2 shows a simplified diagram of the system configuration in Figure 1. In the schematic diagram, only the auxiliary converter 14 is shown as the power supply unit 10. The 48V load 84a of the 48V first system ES4a and the 48V load 84b of the 48V second system ES4b are functionally redundant. One of the 12V loads 81a of the 12V first system ES1a and the 12V load 81b of the 12V second system ES1b are also functionally redundant. The other 12V load 81a of the 12V first system ES1a is a general load and is not redundant.

[0040] Next, referring to Figures 3 to 6, the operation of the multi-output power control device 200 when a ground fault occurs in each power supply system of the multi-output power supply system 100 will be described in order. The following description of operation also serves as a description of the control method executed by the control unit 20 and the program to be operated by the control unit 20. As shown in parentheses in Figures 3 to 6, the overcurrent interruption relay 57 and the relay current detection unit 67 do not need to be provided within the scope of the matters described in this part. Also, in the following description, the main focus of each process of the control unit 20 will not be distinguished in detail as to whether it is the power supply abnormality determination unit 26 or the power supply device instruction unit 22, but will be described as the process of the control unit 20 as a whole.

[0041] (Ground fault in the 48V first system) Figure 3 shows the operation when a ground fault occurs in the 48V first system ES4a. This is assumed to be a ground fault in the harness between the 48V inter-system switch 554 and the 48V load 84a, or a ground fault in the 48V load 84a. The control unit 20 monitors the 48V system voltage Vs48, etc., and if an abnormality is detected, it turns OFF the 48V inter-system switch 554 to prevent the fault from propagating. The control unit 20 then supplies power from the power supply unit 10 to the 48V second system ES4b, and also supplies power from the midpoint converter 40 to the 12V systems ES1a and ES1b.

[0042] (Ground fault in the 48V second system) Figure 4 shows the operation when a ground fault occurs in the 48V second system ES4b. Possible scenarios include a ground fault in the power supply unit 10, a ground fault in the harness between the power supply unit 10 and the 48V load 84b, or a ground fault in the 48V load 84b. The control unit 20 monitors the 48V system voltage Vs48, etc., and if an abnormality is detected, it turns OFF the 48V inter-system switch 554 to prevent the fault from propagating. The control unit 20 then supplies power from the battery pack 700 to the 48V first system ES4a and the 12V systems ES1a and ES1b.

[0043] (Ground fault in the 12V first system) Figure 5 shows the operation when a ground fault occurs in the 12V first system ES1a. This is assumed to be a ground fault in the harness between the 12V inter-system switch 551 and the 12V load 81a, or a ground fault in the 12V load 81a. The control unit 20 monitors the 12V system voltage Vs12, etc., and if an abnormality is detected, it turns OFF the 12V inter-system switch 551 to prevent the fault from propagating. The control unit 20 then supplies power from the power supply unit 10 to the 48V systems ES4a and ES4b, and also supplies power from the midpoint converter 40 to the 12V second system ES1b.

[0044] (Ground Fault in the 12V Second System) FIG. 6 illustrates the operation at the time of a ground fault in the 12V second system ES1b. Cases assumed include a ground fault in the midpoint converter 40, a ground fault in the harness between the midpoint converter 40 and the 12V load 81b, or a ground fault in the 12V load 81b. The control unit 20 monitors the 12V system voltage Vs12 and the like, and when an abnormality is detected, turns off the 12V inter-system switch 551 to prevent propagation of the fault. Then, the control unit 20 supplies power from the power supply unit 10 to the 48V systems ES4a and ES4b, and supplies power from the assembled battery 700 to the 12V first system ES1a.

[0045] (Protection from Ground Fault Current) Next, with reference to FIG. 7 to FIG. 10, the configuration and operation related to protection from ground fault current will be described. As shown in FIG. 7, when a ground fault occurs in the 48V first system ES4a, a ground fault current Igf flows from the ground through the assembled battery 700 to the 48V first system ES4a. At this time, a voltage drop corresponding to "ground fault current × battery resistance" occurs in each of the battery cells connected in series, which may cause fault propagation.

[0046] Accordingly, when an abnormality in any of the 48V systems ES4a, ES4b or the 12V systems ES1a, ES1b is detected, the control unit 20 turns off both the 48V inter-system switch 554 and the 12V inter-system switch 551. This prevents the influence of the ground fault current Igf from reaching the output ends of the auxiliary machine converter 14 and the midpoint converter 40. As indicated by parentheses in FIG. 7, within the scope of the matters described so far, the overcurrent interrupt relay 57 and the relay current detection unit 67 do not have to be provided.

[0047] Next, with reference to FIG. 8, a configuration including the overcurrent interrupt relay 57 as the "overcurrent interrupt unit" will be described. In order to prevent the assembled battery 700 and the harness from overheating when the ground fault current Igf is an overcurrent, it is preferable to provide the "overcurrent interrupt unit that interrupts when an overcurrent flows". In the example of FIG. 8, the overcurrent interrupt unit is provided between the negative terminal (negative electrode terminal) of the lowest battery cell of the assembled battery 700 and the ground. That is, the overcurrent interrupt unit is connected in series with the battery cell between the intermediate terminal 71 and the ground. Note that other arrangement examples of the overcurrent interrupt unit will be described later as other embodiments.

[0048] The "overcurrent interrupting unit" of the first embodiment is configured by an overcurrent interrupting relay 57 that is switched ON / OFF by the control unit 20. As shown in FIG. 8, when a power supply abnormality due to a ground fault in the 48V first system ES4a is detected, the control unit 20 turns OFF both the 48V inter-system switch 554 and the 12V inter-system switch 551, and further turns OFF the overcurrent interrupting relay 57.

[0049] The relay current detection unit 67 detects the relay current I_Ry flowing through the overcurrent interrupting relay 57. If the charging current to the assembled battery 700 is defined as positive, the ground fault current Igf takes a negative value. When the absolute value |I_Ry| of the relay current detected by the relay current detection unit 67 exceeds the overcurrent threshold, the control unit 20 determines that an overcurrent abnormality has occurred. The determination that an overcurrent abnormality has been made by the control unit 20 is also expressed as "an overcurrent abnormality has been detected".

[0050] Here, the overcurrent abnormality of the relay current I_Ry similarly occurs when a ground fault occurs in either the 48V first system ES4a or the 12V first system ES1a. That is, the control unit 20 can determine the ground fault of both the 48V first system ES4a and the 12V first system ES1a based on the fact that the relay current I_Ry is an overcurrent abnormality.

[0051] In addition, the voltage drops in the power supply system where the ground fault has occurred. Accordingly, the control unit 20 can also determine the ground fault based on the fact that the 48V system voltage Vs48 detected by the 48V system voltage detection unit 654 or the 12V system voltage Vs12 detected by the 12V system voltage detection unit 651 falls below the respective power supply abnormality determination threshold. A ground fault in a range where the absolute value |I_Ry| of the relay current is equal to or less than the overcurrent threshold can also be detected by the power supply system voltage.

[0052] In this way, the control unit 20 determines an abnormality in the 48V first system ES4a or the 12V first system ES1a based on at least one of "the absolute value |I_Ry| of the relay current flowing through the overcurrent interrupting relay 57 exceeds the overcurrent threshold" or "the 48V system voltage Vs48 or the 12V system voltage Vs12 falls below the respective power supply abnormality determination threshold".

[0053] The time chart in Figure 9 shows the operation when the 48V power supply malfunctions, corresponding to Figure 8. In the explanation of the time chart, "first system and second system" will be written as "first / second system" as appropriate. Figure 9 shows the changes in the 48V first / second system voltages Vs48a, Vs48b, the 12V first / second system voltages Vs12a, Vs12b, the upper / lower battery block currents Ibk_U, Ibk_L, the relay current I_Ry, and the ON / OFF states of the overcurrent protection relay 57, the 48V system-to-system switch 554, and the 12V system-to-system switch 551. In the following time chart and flowchart, "switch" will be written as "SW".

[0054] Here, when the 48V inter-system switch 554 is ON before time t3, the 48V first system voltage Vs48a and the 48V second system voltage Vs48b are the same and are represented as a single 48V system voltage Vs48. Similarly, when the 12V inter-system switch 551 is ON, the 12V first system voltage Vs12a and the 12V second system voltage Vs12b are the same and are represented as a single 12V system voltage Vs12.

[0055] The upper / lower battery block currents Ibk_U and Ibk_L, and the relay current I_Ry are expressed with the charging current to the battery pack 700 as positive and the discharge current as negative. If there is no leakage current, the lower battery block current Ibk_L and the relay current I_Ry are the same.

[0056] During the charging of the battery pack 700 prior to time t1, the upper / lower battery block currents Ibk_U, Ibk_L, and relay current I_Ry gradually decrease in positive value as charging progresses. When charging of the battery pack 700 is completed at time t1, the upper / lower battery block currents Ibk_U, Ibk_L, and relay current I_Ry become 0A. The 48V system voltage Vs48 and the 12V system voltage Vs12 remain constant from during charging through to after charging is complete.

[0057] When a ground fault occurs in the 48V first system ES4a at time t2, the 48V first / second system voltages Vs48a, Vs48b and the 12V first / second system voltages Vs12a, Vs12b decrease. Also, because a ground fault current Igf flows from ground towards the upper terminal 74, the upper / lower battery block currents Ibk_U, Ibk_L and the relay current I_Ry gradually increase in absolute value to the negative side.

[0058] If the 48V system voltage Vs48 falls below the power supply abnormality detection threshold Vs48_pfth at time t3, the control unit 20 turns off both the 48V system switch 554 and the 12V system switch 551. As a result, the values ​​at time t3 are maintained for the 48V first system voltage Vs48a and the 12V first system voltage Vs12a. Also, the temporary overvoltages for the 48V second system voltage Vs48b and the 12V second system voltage Vs12b are resolved and return to the voltages before time t2.

[0059] If the absolute value of the relay current |I_Ry| exceeds the overcurrent threshold I_EXth at time t4, the control unit 20 turns off the overcurrent interruption relay 57 and interrupts the ground fault current Igf. As a result, the upper / lower battery block currents Ibk_U, Ibk_L and the relay current I_Ry become 0A. This prevents damage to the battery pack 700, inter-system switches 554, 551, harnesses, etc.

[0060] If an abnormality is detected in at least one of the 48V first system ES4a or the 12V first system ES1a, and the 48V second system ES4b or the 12V second system ES1b is experiencing a ground fault, turning off the overcurrent interruption relay 57 first may cause both the second system and the first system to lose power simultaneously. Therefore, the control unit 20 can prevent simultaneous power loss by turning off one or both of the 48V system-to-system switch 554 or the 12V system-to-system switch 551 before turning off the overcurrent interruption relay 57.

[0061] The flowchart in Figure 10 shows the process of the control unit 20 for determining a power supply abnormality. The symbol "S" in the flowchart represents a step. This flowchart also shows the control method executed by the control unit 20 in the multi-output power supply control device 200, and the program that causes the control unit 20 to perform a specific process in the multi-output power supply control device 200.

[0062] In S1, the 48V system switch 554, the 12V system switch 551, and the overcurrent protection relay 57 are turned ON. In S2, it is determined whether the vehicle is starting up, and if NO, the process ends. If the vehicle is starting up, in S3 the control unit 20 turns ON the output of the power supply unit 10. In S4 the control unit 20 turns ON the output of the midpoint converter 40.

[0063] In S5, the control unit 20 determines whether the 48V system voltage Vs48 is greater than or equal to the power supply abnormality determination threshold Vs48_pfth. In S6, the control unit 20 determines whether the 12V system voltage Vs12 is greater than or equal to the power supply abnormality determination threshold Vs12_pfth. If at least one of the 48V system voltage Vs48 or the 12V system voltage Vs12 falls below the power supply abnormality determination threshold, and NO is determined in S5 or S6, in S7 the control unit 20 turns OFF both the 48V system switch 554 and the 12V system switch 551. If YES is determined in both S5 and S6, the process ends with the 48V system switch 554 and the 12V system switch 551 in the ON state.

[0064] In S8, the control unit 20 determines whether the absolute value of the relay current |I_Ry| is less than or equal to the overcurrent threshold I_EXth. If the absolute value of the relay current |I_Ry| exceeds the overcurrent threshold I_EXth and the control unit 20 determines NO in S8, the control unit 20 turns OFF the overcurrent interruption relay 57 in S9. If the control unit 20 determines YES in S8, the process ends with the overcurrent interruption relay 57 remaining ON.

[0065] (Second Embodiment) Referring to Figure 11, the configuration of the multi-output power supply system of the second embodiment will be described. Compared to the configuration of the first embodiment shown in Figure 8, the arrangement of the "overcurrent interruption unit" is different in the second embodiment. The multi-output power supply control device 200 is equipped with an "overcurrent interruption unit that is interrupted when an overcurrent flows" at least one of the following locations: between the upper terminal 74 and the 48V load 84a of the 48V first system ES4a, or between the intermediate terminal 71 and the 12V load 81a of the 12V first system ES1a.

[0066] The "overcurrent interruption unit" of the second embodiment consists of overcurrent interruption relays 584 and 581 that can be switched ON / OFF by the control unit 20. For example, when a power supply abnormality due to a ground fault in the 48V first system ES4a is detected, the control unit 20 turns OFF both the 48V system switch 554 and the 12V system switch 551, and further turns OFF the overcurrent interruption relays 584 and 581. The relay current detection unit 684 detects the relay current I_Ry4 flowing through the overcurrent interruption relay 584. The relay current detection unit 681 detects the relay current I_Ry1 flowing through the overcurrent interruption relay 581.

[0067] If we define the current in the charging direction to the battery pack 700, that is, the current in the direction from the loads 84a and 81a to the battery pack 700, as positive, then the ground fault current Igf will be a negative value. When the control unit 20 detects, for example, the absolute value of the relay current |I_Ry4| exceeds the overcurrent threshold, it determines that there is a power supply abnormality in the 48V first system ES4a or the 12V first system ES1a and turns off the overcurrent interruption relay 584. Similarly, when the control unit 20 detects that there is a power supply abnormality when the absolute value of the relay current |I_Ry1| exceeds the overcurrent threshold, it turns off the overcurrent interruption relay 581.

[0068] Furthermore, similar to the first embodiment, the control unit 20 can determine a ground fault based on whether the 48V system voltage Vs48 detected by the 48V system voltage detection unit 654 or the 12V system voltage Vs12 detected by the 12V system voltage detection unit 651 falls below the respective power supply abnormality determination threshold. Ground faults in which the absolute values ​​of the relay currents |I_Ry4| and |I_Ry1| are below the overcurrent threshold can also be detected by the power supply system voltage.

[0069] In this manner, the control unit 20 determines an abnormality in the 48V first system ES4a or the 12V first system ES1a based on at least one of the following: "the absolute value of the relay current flowing through the overcurrent interruption relay 584 |I_Ry4| or the absolute value of the relay current flowing through the overcurrent interruption relay 581 |I_Ry1| has exceeded the overcurrent threshold," or "the 48V system voltage Vs48 or the 12V system voltage Vs12 has fallen below the respective power supply abnormality determination threshold."

[0070] Furthermore, in the configuration of the second embodiment, when a short-circuit fault occurs in the 48V first system ES4a or the 12V first system ES1a and an overcurrent flows, either the overcurrent interruption relay 584 or the overcurrent interruption relay 581 is tripped. Therefore, propagation of the short-circuit fault between the 48V first system ES4a and the 12V first system ES1a can be prevented.

[0071] (Other Embodiments) (a) Figures 12 and 13 show other embodiments in which the arrangement of the overcurrent interruption relay 57 as the "overcurrent interruption unit" differs from the first embodiment shown in Figure 8. As shown in Figure 12, the overcurrent interruption relay 57 may be connected in the middle of the lower battery block 70L between the negative terminal of an adjacent upper battery cell and the positive terminal of a lower battery cell. As shown in Figure 13, the overcurrent interruption relay 57 may be connected between the intermediate terminal 71 and the positive terminal of the uppermost battery cell of the lower battery block 70L. Thus, the overcurrent interruption unit only needs to be connected in series with the battery cell at any position between the intermediate terminal 71 (i.e., the positive terminal of the battery cell of the battery pack 700 to which the 12V first system ES1a is connected) and ground.

[0072] (b) The voltages of the "high-voltage power supply system" and "one or more low-voltage power supply systems" are not limited to 48V and 12V, but may be a combination of a relatively high voltage and a relatively low voltage. In addition, the multi-output power supply system 100 may include, for example, a 24V system in addition to the 12V system as "one or more low-voltage power supply systems".

[0073] (c) The multi-output power supply system 100 only needs to be equipped with high-voltage system switches in at least the high-voltage power supply system, and does not need to be equipped with low-voltage system switches in one or more low-voltage power supply systems. In that case, the control unit 20 can determine an abnormality in at least the high-voltage power supply system, and based on the determination result, it can switch the high-voltage system switches ON / OFF.

[0074] (d) Instead of the overcurrent interruption relay 57 in the first embodiment and the overcurrent interruption relays 584 and 581 in the second embodiment, the "overcurrent interruption unit" may be composed of a fuse. In that case, the power supply abnormality determination unit 26 of the control unit 20 does not need to determine a power supply abnormality based on the relay currents I_Ry, I_Ry4, I_Ry1, or the 48V system voltage Vs48 and 12V system voltage Vs12. If the fuse blows due to overcurrent, the part needs to be replaced.

[0075] (e) The power supply unit 10 that supplies high voltage (e.g., 48V) is not limited to the auxiliary converter 14 shown in Figure 1, etc., but may be composed of a generator such as an alternator.

[0076] (f) The circuit configuration of the midpoint converter 40 is not limited to the configuration of the above embodiment. The midpoint converter 40 is not limited to one that can exchange power by boosting or stepping up in both directions between the 48V systems (high voltage power supply systems) ES4a, ES4b and the 12V systems (low voltage power supply systems) ES1a, ES1b, but may also be capable of exchanging power in only one direction. For example, it may only be possible to step down from the 48V systems ES4a, ES4b to the 12V systems ES1a, ES1b.

[0077] (g) The multi-output power supply system of the present disclosure may be mounted not only on a vehicle, but also on a "mobile body having multiple power supply systems, each with a load connected to it," or a "non-mobile body having multiple power supply systems, each with a load connected to it."

[0078] The present disclosure is not limited to these embodiments and can be implemented in various forms without departing from its spirit.

[0079] (Disclosure of Technical Ideas) This specification discloses several technical ideas as described in the following paragraphs. Some paragraphs may be written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs may be written in a multiple dependent form, where they refer to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical ideas.

[0080] (Technical Concept 1) A multi-output power supply system (100) is applied to a battery pack (700) in which multiple battery cells are connected in series, the positive terminal (74) of the uppermost battery cell is connected to a high-voltage power supply system (ES4a, ES4b), and the positive terminal (71) of one or more battery cells other than the uppermost battery cell of the battery pack is connected to one or more low-voltage power supply systems (ES1a, ES1b), and the high-voltage power supply system and the low-voltage power supply system are each connected to loads (84a, 84b, 81a, 81b), and the battery pack can be charged from a power supply unit (10) connected to the positive terminal of the uppermost battery cell of the battery pack, and power can also be supplied to the high-voltage power supply system, and the system includes: a midpoint converter (40) that can exchange power unidirectionally or bidirectionally between the high-voltage power supply system and the low-voltage power supply system; and a high-voltage system switch (554) provided between the power supply unit and the positive terminal of the uppermost battery cell of the battery pack. A multi-output power control device comprising: a control unit (20) that controls the output of the power supply unit and the midpoint converter, and is capable of determining at least an abnormality in the high-voltage power supply system, and switches the high-voltage inter-system switch ON / OFF based on the determination result, wherein the high-voltage inter-system switch divides the high-voltage power supply system into a high-voltage first power supply system (ES4a) connected to the battery pack side of the high-voltage inter-system switch and a high-voltage second power supply system (ES4b) connected to the power supply unit side of the high-voltage inter-system switch. (Technical Concept 2) The multi-output power control device according to Technical Concept 1, further comprising a low-voltage system switch (551) provided between the midpoint converter and the positive terminal of a battery cell to which the low-voltage power supply system is connected in the battery pack, wherein the control unit is further capable of determining an abnormality in the low-voltage power supply system and switches the low-voltage system switch ON / OFF based on the determination result, and the low-voltage system switch divides the low-voltage power supply system into a low-voltage first power supply system (ES1a) connected to the battery pack side of the low-voltage system switch and a low-voltage second power supply system (ES1b) connected to the midpoint converter side of the low-voltage system switch.(Technical Idea 3) The control unit turns off the high-voltage system switch when there is an abnormality in the high-voltage first power supply system, supplies power from the power supply unit to the high-voltage second power supply system, and supplies power from the midpoint converter to the low-voltage power supply system, as described in Technical Idea 2. (Technical Idea 4) The control unit turns off the high-voltage system switch when there is an abnormality in the high-voltage second power supply system, and supplies power from the battery pack to the high-voltage first power supply system and the low-voltage power supply system, as described in Technical Idea 2 or 3. (Technical Idea 5) The control unit turns off the low-voltage system switch when there is an abnormality in the low-voltage first power supply system, supplies power from the power supply unit to the high-voltage power supply system, and supplies power from the midpoint converter to the low-voltage second power supply system, as described in any one of Technical Ideas 2 to 4. (Technical Idea 6) The control unit turns OFF the low-voltage inter-system switch when there is an abnormality in the low-voltage second power supply system, supplies power from the power supply unit to the high-voltage power supply system, and supplies power from the battery pack to the low-voltage first power supply system, as described in any one of Technical Ideas 2 to 5. (Technical Idea 7) The control unit turns OFF both the high-voltage inter-system switch and the low-voltage inter-system switch when an abnormality is detected in either the high-voltage power supply system or the low-voltage power supply system, as described in Technical Idea 2. (Technical Idea 8) The multi-output power supply control device according to any one of Technical Ideas 2 to 7, further comprising an overcurrent interruption unit (57) connected in series with the battery cell between the positive terminal and ground of the battery cell of the battery pack to which the low-voltage first power supply system is connected, and which is interrupted when an overcurrent flows. (Technical Concept 9) The multi-output power control device according to Technical Concept 8, wherein the overcurrent interruption unit is composed of an overcurrent interruption relay that is switched ON / OFF by the control unit, and the control unit turns OFF the overcurrent interruption relay when an abnormality is detected in at least one of the high-voltage first power supply system or the low-voltage first power supply system.(Technical Concept 10) The multi-output power control device according to Technical Concept 9, wherein the control unit turns off one or both of the high-voltage inter-system switches or the low-voltage inter-system switches and then turns off the overcurrent interruption relay when an abnormality is detected in at least one of the high-voltage first power supply system or the low-voltage first power supply system. (Technical Concept 11) The multi-output power control device according to Technical Concept 9 or 10, wherein the control unit determines an abnormality in the high-voltage first power supply system or the low-voltage first power supply system based on at least one of the following: the absolute value of the relay current flowing through the overcurrent interruption relay exceeds an overcurrent threshold, or the voltage of the high-voltage first power supply system or the low-voltage first power supply system falls below the respective power supply abnormality determination threshold. (Technical Concept 12) A multi-output power supply control device according to any one of Technical Concepts 2 to 7, further comprising an overcurrent interruption unit (584, 581) that is interrupted when an overcurrent flows between the positive terminal of the uppermost battery cell of the battery pack and the load of the high-voltage first power supply system, or between the positive terminal of a battery cell other than the uppermost one of the battery pack and the load of the low-voltage first power supply system.

[0081] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0082] This disclosure is described in accordance with embodiments. However, this disclosure is not limited to such embodiments and structures. This disclosure also includes various modifications and variations within the scope of equivalents. Furthermore, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer elements, fall within the scope and idea of ​​this disclosure.

Claims

1. Applicable to a multi-output power supply system (100) in which a high-voltage power supply system (ES4a, ES4b) is connected to the positive terminal (74) of the uppermost battery cell of a battery pack (700) in which multiple battery cells are connected in series, and one or more low-voltage power supply systems (ES1a, ES1b) are connected to the positive terminal (71) of one or more battery cells other than the uppermost one of the battery pack, and loads (84a, 84b, 81a, 81b) are connected to the high-voltage power supply system and the low-voltage power supply system, respectively, and the battery pack can be charged from a power supply unit (10) connected to the positive terminal of the uppermost battery cell of the battery pack and power can be supplied to the high-voltage power supply system, the system comprises: a midpoint converter (40) capable of unidirectional or bidirectional power exchange between the high-voltage power supply system and the low-voltage power supply system, and a high-voltage system switch (554) provided between the power supply unit and the positive terminal of the uppermost battery cell of the battery pack, A multi-output power control device comprising: a control unit (20) that controls the output of the power supply unit and the midpoint converter, and is capable of determining at least an abnormality in the high-voltage power supply system, and switches the high-voltage inter-system switch ON / OFF based on the determination result, wherein the high-voltage inter-system switch divides the high-voltage power supply system into a high-voltage first power supply system (ES4a) connected to the battery pack side of the high-voltage inter-system switch and a high-voltage second power supply system (ES4b) connected to the power supply unit side of the high-voltage inter-system switch.

2. The multi-output power control device according to claim 1, further comprising a low-voltage system switch (551) provided between the midpoint converter and the positive terminal of a battery cell to which the low-voltage power supply system is connected in the battery pack, wherein the control unit is further capable of determining an abnormality in the low-voltage power supply system and switches the low-voltage system switch ON / OFF based on the determination result, and the low-voltage system switch divides the low-voltage power supply system into a low-voltage first power supply system (ES1a) connected to the battery pack side of the low-voltage system switch and a low-voltage second power supply system (ES1b) connected to the midpoint converter side of the low-voltage system switch.

3. The multi-output power control device according to claim 2, wherein the control unit turns off the high-voltage inter-system switch when there is an abnormality in the high-voltage first power supply system, supplies power from the power supply unit to the high-voltage second power supply system, and supplies power from the midpoint converter to the low-voltage power supply system.

4. The multi-output power control device according to claim 2, wherein the control unit turns off the high-voltage inter-system switch when there is an abnormality in the high-voltage second power supply system, and supplies power from the battery pack to the high-voltage first power supply system and the low-voltage power supply system.

5. The multi-output power control device according to claim 2, wherein the control unit turns off the low-voltage inter-system switch when there is an abnormality in the low-voltage first power supply system, supplies power from the power supply unit to the high-voltage power supply system, and supplies power from the midpoint converter to the low-voltage second power supply system.

6. The multi-output power control device according to claim 2, wherein the control unit turns off the low-voltage inter-system switch when there is an abnormality in the low-voltage second power supply system, supplies power from the power supply unit to the high-voltage power supply system, and supplies power from the battery pack to the low-voltage first power supply system.

7. The multi-output power control device according to claim 2, wherein the control unit turns OFF both the high-voltage system switch and the low-voltage system switch when an abnormality is detected in either the high-voltage power supply system or the low-voltage power supply system.

8. The multi-output power control device according to claim 2, further comprising an overcurrent interruption unit (57) connected in series with the battery cell between the positive terminal of the battery cell of the battery pack to which the low-voltage first power supply system is connected and ground, and which is interrupted when an overcurrent flows.

9. The multi-output power control device according to claim 8, wherein the overcurrent interruption unit is composed of an overcurrent interruption relay that is switched ON / OFF by the control unit, and the control unit turns OFF the overcurrent interruption relay when an abnormality is detected in at least one of the high-voltage first power supply system or the low-voltage first power supply system.

10. The multi-output power supply control device according to claim 9, wherein when an abnormality is detected in at least one of the high-voltage first power supply system or the low-voltage first power supply system, the control unit turns off one or both of the high-voltage system-to-system switch or the low-voltage system-to-system switch and then turns off the overcurrent interruption relay.

11. The multi-output power control device according to claim 9, wherein the control unit determines an abnormality in the high-voltage first power supply system or the low-voltage first power supply system based on at least one of the following: the absolute value of the relay current flowing through the overcurrent interruption relay exceeds an overcurrent threshold, or the voltage of the high-voltage first power supply system or the low-voltage first power supply system falls below the respective power supply abnormality determination threshold.

12. The multi-output power control device according to claim 2, further comprising an overcurrent interruption unit (584, 581) that is interrupted when an overcurrent flows between the positive terminal of the uppermost battery cell of the battery pack and the load of the high-voltage first power supply system, or between the positive terminal of a battery cell other than the uppermost one of the battery pack and the load of the low-voltage first power supply system.

13. A multi-output power supply system comprising: a multi-output power control device (200) according to any one of claims 1 to 12; a battery pack (700) in which a plurality of battery cells are connected in series; loads (84a, 84b, 81a, 81b) connected to a high-voltage power supply system (ES4a, ES4b) connected to the positive terminal of the uppermost battery cell of the battery pack, and a load (84a, 84b, 81a, 81b) connected to a load (ES1a, ES1b) connected to the positive terminal of one or more battery cells other than the uppermost battery cell of the battery pack; and a power supply unit (10) connected to the positive terminal of the uppermost battery cell of the battery pack, capable of charging the battery pack and supplying power to the high-voltage power supply system.

14. Applicable to a multi-output power supply system (100) in which a high-voltage power supply system (ES4a, ES4b) is connected to the positive terminal (74) of the uppermost battery cell of a battery pack (700) in which multiple battery cells are connected in series, and one or more low-voltage power supply systems (ES1a, ES1b) are connected to the positive terminal (71) of one or more battery cells other than the uppermost one of the battery pack, and loads (84a, 84b, 81a, 81b) are connected to the high-voltage power supply system and the low-voltage power supply system, respectively, and the battery pack can be charged from a power supply unit (10) connected to the positive terminal of the uppermost battery cell of the battery pack and power can be supplied to the high-voltage power supply system, the system comprises: a midpoint converter (40) capable of unidirectional or bidirectional power exchange between the high-voltage power supply system and the low-voltage power supply system; and a high-voltage system switch (554) provided between the power supply unit and the positive terminal of the uppermost battery cell of the battery pack, The system comprises: a midpoint converter and a low-voltage system-to-system switch (551) provided between the midpoint converter and the positive terminal of a battery cell to which the low-voltage power supply system is connected in the battery pack; and a control unit (20) that controls the output of the power supply unit and the midpoint converter, and can determine abnormalities in the high-voltage power supply system and the low-voltage power supply system, and switches the high-voltage system-to-system switch and the low-voltage power supply system ON / OFF based on the determination result, wherein the high-voltage system-to-system switch divides the high-voltage power supply system into a high-voltage first power supply system (ES4a) connected to the battery pack side of the high-voltage system-to-system switch and a high-voltage second power supply system (ES4b) connected to the power supply unit side of the high-voltage system-to-system switch. A control method performed by the control unit in a multi-output power control device in which the low-voltage inter-system switch divides the low-voltage power supply system into a low-voltage first power supply system (ES1a) connected to the battery pack side of the low-voltage inter-system switch and a low-voltage second power supply system (ES1b) connected to the midpoint converter side of the low-voltage inter-system switch, wherein the control unit determines abnormalities in the high-voltage power supply system and the low-voltage power supply system, turns off the high-voltage inter-system switch when there is an abnormality in the high-voltage power supply system, and turns off the low-voltage inter-system switch when there is an abnormality in the low-voltage power supply system.

15. Applicable to a multi-output power supply system (100) in which a high-voltage power supply system (ES4a, ES4b) is connected to the positive terminal (74) of the uppermost battery cell of a battery pack (700) in which multiple battery cells are connected in series, and one or more low-voltage power supply systems (ES1a, ES1b) are connected to the positive terminal (71) of one or more battery cells other than the uppermost one of the battery pack, and loads (84a, 84b, 81a, 81b) are connected to the high-voltage power supply system and the low-voltage power supply system, respectively, and the battery pack can be charged from a power supply unit (10) connected to the positive terminal of the uppermost battery cell of the battery pack and power can be supplied to the high-voltage power supply system, the system comprises: a midpoint converter (40) capable of unidirectional or bidirectional power exchange between the high-voltage power supply system and the low-voltage power supply system; and a high-voltage system switch (554) provided between the power supply unit and the positive terminal of the uppermost battery cell of the battery pack, The system comprises: a midpoint converter and a low-voltage system-to-system switch (551) provided between the midpoint converter and the positive terminal of a battery cell to which the low-voltage power supply system is connected in the battery pack; and a control unit (20) that controls the output of the power supply unit and the midpoint converter, and can determine abnormalities in the high-voltage power supply system and the low-voltage power supply system, and switches the high-voltage system-to-system switch and the low-voltage power supply system ON / OFF based on the determination result, wherein the high-voltage system-to-system switch divides the high-voltage power supply system into a high-voltage first power supply system (ES4a) connected to the battery pack side of the high-voltage system-to-system switch and a high-voltage second power supply system (ES4b) connected to the power supply unit side of the high-voltage system-to-system switch. The low-voltage inter-system switch divides the low-voltage power supply system into a low-voltage first power supply system (ES1a) connected to the battery pack side of the low-voltage inter-system switch and a low-voltage second power supply system (ES1b) connected to the midpoint converter side of the low-voltage inter-system switch, and the control unit is programmed to determine abnormalities in the high-voltage power supply system and the low-voltage power supply system, to turn off the high-voltage inter-system switch when there is an abnormality in the high-voltage power supply system, and to turn off the low-voltage inter-system switch when there is an abnormality in the low-voltage power supply system.

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