Power supply system and program

Abstract

In a power supply system (30), at least a part of a third X electrical path is shared with at least parts of a second X electrical path and a second Y electrical path, and the shared common path (L10) is provided with a shared current sensor (A13).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2022-197450, filed on December 9, 2022, the contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a power supply system and a program. [Background technology]

[0003] BACKGROUND ART As described in Patent Document 1, a method for determining whether a system main relay has welded in a power supply system for a vehicle is known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-99129 Summary of the Invention

[0005] Meanwhile, there is a power supply system under development that has a plurality of power storage units, in which some of the power storage units are disconnected from a high-voltage circuit and connected to a low-voltage circuit to supply power to a low-voltage load. In such a power supply system, a large number of current sensors are required to determine a fault, and there is room for improvement in the circuit configuration.

[0006] A primary object of the present disclosure is to provide a power supply system and a program that can reduce the number of current sensors.

[0007] A first power supply system for solving the above problem comprises: A power supply system including a plurality of power storage units, the power supply system being connected to a high-voltage circuit via a high-voltage power supply line and a high-voltage ground line, and being connected to a low-voltage circuit via a low-voltage power supply line and a low-voltage ground line, a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit; a switch control unit that controls the first switch unit, the second switch unit, and the third switch unit; The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on the opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch that switches between energization and de-energization of a third Y electrical path that is provided between the negative electrode terminal of the second power storage unit and the low-voltage ground line, at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path; A shared current sensor is provided on the common path.

[0008] This allows the number of current sensors to be reduced.

[0009] A first program for solving the above problem is: A power supply system including a plurality of power storage units, the power supply system being connected to a high-voltage circuit via a high-voltage power supply line and a high-voltage ground line, and being connected to a low-voltage circuit via a low-voltage power supply line and a low-voltage ground line, a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit, The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on the opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch configured to switch between energization and deenergization of a third Y electrical path provided between a negative electrode terminal of the second power storage unit and the low-voltage ground line, a switch control process for controlling the first switch unit, the second switch unit, and the third switch unit; a failure determination process for determining whether or not there is a failure in the first switch unit, the second switch unit, or the third switch unit; at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path; A shared current sensor is provided on the shared common path, In the failure determination process, a failure determination is made for the second switch unit based on the measurement results of the shared current sensor when the on / off state of the second switch unit is switched, and a failure determination is made for the third switch unit based on the measurement results of the shared current sensor when the on / off state of the third switch unit is switched.

[0010] This allows the number of current sensors to be reduced. [Brief explanation of the drawings]

[0011] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 1 is a configuration diagram of an in-vehicle system according to a first embodiment; [Figure 2] FIG. 2 is a diagram showing a connection state of a power supply system; [Figure 3] FIG. 3 is a diagram showing a connection state of a power supply system; [Figure 4] FIG. 4 is a diagram showing a connection state of a power supply system; [Figure 5] FIG. 5 is a diagram showing a connection state of a power supply system; [Figure 6] FIG. 6 is a diagram showing a connection state of a power supply system; [Figure 7] FIG. 7 is a diagram showing a connection state of a power supply system; [Figure 8] FIG. 8 is a diagram showing a connection state of a power supply system; [Figure 9] FIG. 9 is a flowchart of the startup process. [Figure 10] FIG. 10 is a diagram showing the relationship between the state of the third switch unit and the detection value in a normal state; [Figure 11] FIG. 11 is a diagram showing the relationship between the state of the second switch section and the detection value in a normal state; [Figure 12] FIG. 12 is a flowchart of the stop process. [Figure 13]FIG. 13 is a diagram showing a relationship between a state of a third switch unit and a detection value in Modification 1; [Figure 14] FIG. 14 is a diagram showing a relationship between a state of a third switch unit and a detection value in Modification 2; [Figure 15] FIG. 15 is a diagram showing the relationship between the state of the third switch unit and the detection value in Modification 3; [Figure 16] FIG. 16 is a diagram showing a third voltage sensor in Modification 4; [Figure 17] FIG. 17 is a diagram showing the relationship between the state of the third switch unit and the detection value in Modification 4; [Figure 18] FIG. 18 is a diagram showing the relationship between the state of the third switch unit and the detection value in Modification 5; [Figure 19] FIG. 19 is a diagram showing the relationship between the state of the second switch section and the detection value in Modification 7; [Figure 20] FIG. 20 is a diagram showing a fourth voltage sensor in Modification 8; [Figure 21] FIG. 21 is a diagram showing the relationship between the state of the second switch section and the detection value in Modification 8; [Figure 22] FIG. 22 is a diagram showing the relationship between the state of the second switch section and the detection value in Modification 9; [Figure 23] FIG. 23 is a diagram showing a connection state of a power supply system in a tenth modification; [Figure 24] FIG. 24 is a diagram showing a connection state of a power supply system in Modification 11; [Figure 25] FIG. 25 is a diagram showing a connection state of a power supply system in a twelfth modification; [Figure 26] FIG. 26 is a diagram showing a connection state of a power supply system in a thirteenth modification; [Figure 27] FIG. 27 is a diagram showing the switching order of each switch in Modification 14; [Figure 28] FIG. 28 is a diagram showing the switching order of each switch in Modification 14; [Figure 29]FIG. 29 is a diagram showing the switching order of each switch in Modification 15; [Figure 30] FIG. 30 is a diagram showing the switching order of each switch in Modification 15; [Figure 31] FIG. 31 is a diagram showing the switching order of each switch in Modification 16; [Figure 32] FIG. 32 is a diagram showing the switching order of each switch in Modification 16; [Figure 33] FIG. 33 is a diagram showing the switching order of each switch in Modification 17; [Figure 34] FIG. 34 is a diagram showing the switching order of each switch in Modification 17; [Figure 35] FIG. 35 is a diagram showing the switching order of each switch in Modification 17; [Figure 36] FIG. 36 is a diagram showing the relationship between the state of the switch and the detection value in Modification 17; [Figure 37] FIG. 37 is a diagram showing the relationship between the state of the switch and the detection value in Modification 17; [Figure 38] FIG. 38 is a diagram showing the switching order of each switch in Modification 18; [Figure 39] FIG. 39 is a diagram showing the switching order of each switch in Modification 18. [Figure 40] FIG. 40 is a diagram showing the switching order of each switch in Modification 18. [Figure 41] FIG. 41 is a diagram showing the switching order of each switch in Modification 19. [Figure 42] FIG. 42 is a diagram showing the switching order of each switch in Modification 19. [Figure 43] FIG. 43 is a diagram showing the switching order of each switch in Modification 20. [Figure 44] FIG. 44 is a diagram showing the switching order of each switch in Modification 20. [Figure 45] FIG. 45 is a diagram showing the switching order of each switch in Modification 21. [Figure 46] FIG. 46 is a diagram showing the switching order of each switch in Modification 21. [Figure 47] FIG. 47 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 48] FIG. 48 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 49] FIG. 49 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 50] FIG. 50 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 51] FIG. 51 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 52] FIG. 52 is a diagram showing a connection state of a power supply system according to a modified example; [Figure 53] FIG. 53 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 54] FIG. 54 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 55] FIG. 55 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 56] FIG. 56 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 57] FIG. 57 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 58] FIG. 58 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 59] FIG. 59 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 60] FIG. 60 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 61] FIG. 61 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 62] FIG. 62 is a diagram showing a connection state of a power supply system according to a modified example; [Figure 63] FIG. 63 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 64]FIG. 64 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 65] FIG. 65 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 66] FIG. 66 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 67] FIG. 67 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 68] FIG. 68 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 69] FIG. 69 is a diagram showing a connection state of a power supply system according to a modified example. [Figure 70] FIG. 70 is a diagram showing a connection state of a power supply system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Several embodiments and their modified examples will be described with reference to the drawings. In several embodiments and their modified examples, functionally and / or structurally corresponding and / or associated parts may be assigned the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0013] (First embodiment) A first embodiment of a power supply system according to the present disclosure will now be described with reference to the drawings. The power supply system of this embodiment is installed in a vehicle such as an electric vehicle or a hybrid vehicle, and constitutes an in-vehicle system.

[0014] As shown in FIG. 1, the in-vehicle system includes a motor 10, an inverter 20 (inverter circuit), a high-voltage power supply line H1, a high-voltage ground line L1, a low-voltage power supply line H2, a low-voltage ground line L2, a power supply system 30, and a DC-DC converter 70 (voltage converter).

[0015] The motor 10 has a plurality of armature windings. In this embodiment, the motor 10 is a three-phase synchronous machine and has star-connected U-, V-, and W-phase armature windings 11 and a rotor (not shown). The armature windings 11 of each phase are arranged with an electrical angle of 120°. The motor 10 is, for example, a permanent magnet synchronous machine. The rotor is capable of transmitting power to the drive wheels of the vehicle. Therefore, the motor 10 serves as a source of torque for propelling the vehicle.

[0016] The inverter 20 includes three phases of series-connected upper-arm switches SWH and lower-arm switches SWL. An upper-arm diode DH, which is a freewheeling diode, is connected in antiparallel to the upper-arm switch SWH, and a lower-arm diode DL, which is also a freewheeling diode, is connected in antiparallel to the lower-arm switch SWL. In this embodiment, each of the switches SWH and SWL is an IGBT.

[0017] The inverter 20 includes an inverter-side smoothing capacitor 21 (first smoothing capacitor). A high-potential terminal of the inverter-side smoothing capacitor 21 is connected to a high-voltage power supply line H1. A low-potential terminal of the inverter-side smoothing capacitor 21 is connected to a high-voltage ground line L1. The inverter-side smoothing capacitor 21 may be provided outside the inverter 20.

[0018] In each phase, a first end of the armature winding 11 is connected to a connection point between an emitter, which is a low-potential terminal of the upper arm switch SWH, and a collector, which is a high-potential terminal of the lower arm switch SWL, via a conductive member 23 such as a bus bar. Second ends of the armature windings 11 of each phase are connected to each other at a neutral point. In this embodiment, the armature windings 11 of each phase are set to have the same number of turns. As a result, the armature windings 11 of each phase are set to have the same inductance, for example.

[0019] The collectors of the upper arm switches SWH of each phase are connected to the high-voltage power supply line H1. The emitters of the lower arm switches SWL of each phase are connected to the high-voltage ground line L1. The high-voltage ground line L1 is connected to the first ground FG. Therefore, the motor 10 is connected to the high-voltage power supply line H1 via the inverter 20. Note that both or either one of the motor 10 and the inverter 20 may or may not be included in the power supply system 30.

[0020] Various high-voltage loads 71 ​​(not shown) are connected between the high-voltage power supply line H1 and the high-voltage ground line L1. The high-voltage loads 71 ​​are electrical loads requiring a high voltage, such as an air compressor. The motor 10 and a DC-DC converter 70 (described later) are also types of high-voltage loads 71. In this embodiment, the motor 10, the inverter 20, the high-voltage loads 71, and the electrical paths connecting them form a high-voltage circuit 75, which is connected to the power supply system 30 via the high-voltage power supply line H1 and the high-voltage ground line L1.

[0021] Various low-voltage loads 72 are connected between the low-voltage power supply line H2 and the low-voltage ground line L2. The low-voltage loads 72 are electrical loads that require a low voltage (lower than the high-voltage load 71), and include, for example, various control devices such as ECUs. Some low-voltage loads 72, such as ECUs, require a dark current (standby current). The low-voltage ground line L2 is connected to a second ground SG. The second ground SG is insulated from the first ground FG. In this embodiment, the low-voltage loads 72 and the electrical paths connecting them form a low-voltage circuit 76, and the low-voltage circuit 76 is connected to the power supply system 30 via the low-voltage power supply line H2 and the low-voltage ground line L2.

[0022] The DC-DC converter 70 has a function of converting the voltage of the input power. The DC-DC converter 70 is connected between the high-voltage power supply line H1 and the high-voltage ground line L1, and is configured to step down the voltage of the power input from the high-voltage power supply line H1 side and supply it to a low-voltage circuit 76 side including a low-voltage load 72 connected to the low-voltage power supply line H2 via a power transmission line L3.

[0023] Conversely, the DC-DC converter 70 is configured to boost the voltage of power input from the low-voltage power supply line H2 via the power transmission line L3 and supply it to a high-voltage load 71 connected to the high-voltage power supply line H1. The DC-DC converter 70 is controlled by a control device 100, which will be described later. The DC-DC converter 70 may or may not be included in the power supply system 30. In the first embodiment, the DC-DC converter 70 does not need to have a boost function.

[0024] Next, the power supply system 30 will be described. The power supply system 30 includes a first storage battery 31 (corresponding to the "first power storage unit"), a second storage battery 32 (corresponding to the "second power storage unit"), and a third storage battery 33 (corresponding to the "third power storage unit"). Each of the storage batteries 31, 32, and 33 serves as a power supply source for driving and rotating the rotor of the motor 10. Each of the storage batteries 31, 32, and 33 is an assembled battery configured as a series connection of battery cells, which are single cells. The battery cells are, for example, secondary batteries such as lithium-ion batteries.

[0025] The first storage battery 31 has the highest output voltage among the storage batteries 31, 32, and 33, and has an output voltage of, for example, 400 V. The second storage battery 32 has a lower output voltage than the first storage battery 31, and has an output voltage of, for example, 12 V. The output voltage of the third storage battery 33 is arbitrary, and in this embodiment, the output voltage is, for example, 200 V. The inter-terminal voltage of each of the storage batteries 31 to 33 can be changed arbitrarily.

[0026] The power supply system 30 includes a first-A switch SW1a provided in a first-A electrical path 1A that connects the positive terminal of the first storage battery 31 and the high-voltage power line H1. The first-A switch SW1a switches between energization and de-energization between the positive terminal of the first storage battery 31 and the high-voltage power line H1, in this embodiment, the first-A electrical path 1A.

[0027] As in the present embodiment, a series connection of the precharge switch Pre_P and the resistor R1 may be connected in parallel to the first A switch SW1a. The first A switch SW1a corresponds to the system main relay switch on the high potential side.

[0028] The power supply system 30 includes a first-B switch SW1b provided in a first-B electrical path 1B that connects the negative terminal of the first storage battery 31 and the high-voltage ground line L1. The first-B switch SW1b switches between energization and de-energization between the negative terminal of the first storage battery 31 and the high-voltage ground line L1, in this embodiment, the first-B electrical path 1B.

[0029] The power supply system 30 includes a first C switch SW1c provided on a first C electrical path 1C that connects the negative terminal of the first storage battery 31 and the positive terminal of a first series-connected body 40 made up of the second storage battery 32 and the third storage battery 33. The first C switch SW1c switches between energizing and de-energizing the first C electrical path 1C between the negative terminal of the first storage battery 31 and the positive terminal of the first series-connected body 40, in this embodiment.

[0030] The first series connection 40 is configured by connecting the positive terminal of the second storage battery 32 in series with the negative terminal of the third storage battery 33. Therefore, in this embodiment, the positive terminal of the first series connection 40 corresponds to the positive terminal of the third storage battery 33, and the negative terminal of the first series connection 40 corresponds to the negative terminal of the second storage battery 32. It can also be said that the first C switch SW1c has a function of switching between energization and de-energization between the first storage battery 31 and the second storage battery 32.

[0031] The power supply system 30 includes a first-D switch SW1d and a first-E switch SW1e provided on a first-D electrical path 1D that connects the neutral point of the armature winding 11 of the motor 10 and the positive terminal of the first series-connected body 40. One end of the first-D electrical path 1D is connected in the first-C electrical path 1C between the first-C switch SW1c and the positive terminal of the third storage battery 33. The first-D switch SW1d and the first-E switch SW1e switch between energizing and deenergizing the first-D electrical path 1D.

[0032] In addition, a firstE switch SW1e is provided on the neutral point side of the firstD electrical path 1D. Furthermore, a neutral point side smoothing capacitor C1 (second smoothing capacitor) is provided between the firstD electrical path 1D and the high-voltage ground line L1. A high potential side terminal of this neutral point side smoothing capacitor C1 is connected between the firstD switch SW1d and the firstE switch SW1e in the firstD electrical path 1D.

[0033] 1, the armature winding 11 of the motor 10 is connected to the high-voltage ground line L1 via the inverter 20. Therefore, when the lower arm switch SWL of the inverter 20 is turned on, the first D electrical path 1D can be connected to the high-voltage ground line L1. Therefore, depending on the connection state, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e have the function of switching between energization and de-energization between the negative terminal of the first storage battery 31 and the high-voltage ground line L1.

[0034] The power supply system 30 includes a second-A switch SW2a provided on a second-A electrical path 2A that connects the negative terminal of the third storage battery 33 and the positive terminal of the second storage battery 32. The second-A switch SW2a switches between energizing and de-energizing the second-A electrical path 2A between the negative terminal of the third storage battery 33 and the positive terminal of the second storage battery 32, in this embodiment.

[0035] 1, the first C switch SW1c, the third storage battery 33, and the second A switch SW2a are connected in series between the first storage battery 31 and the second storage battery 32. Therefore, when the first C switch SW1c is turned on, the second A switch SW2a switches between energizing and deenergizing the first storage battery 31 and the second storage battery 32, instead of the first C switch SW1c.

[0036] The power supply system 30 includes a secondB switch SW2b provided in a secondB electrical path 2B that connects the negative terminal of the first series connection 40 and the high-voltage ground line L1. The secondB switch SW2b switches between energizing and de-energizing the secondB electrical path 2B, that is, between the negative terminal of the first series connection 40 and the high-voltage ground line L1, i.e., between energizing and de-energizing the secondB electrical path 2B. The secondB switch SW2b corresponds to a system main relay switch on the low-potential side.

[0037] The power supply system 30 includes a 3A switch SW3a provided on a 3A electrical path 3A that connects the positive terminal of the second storage battery 32 and the low-voltage power supply line H2. The 3A switch SW3a switches between energizing and deenergizing the 3A electrical path 3A between the positive terminal of the second storage battery 32 and the low-voltage power supply line H2, in this embodiment.

[0038] One end of the 3A electrical path 3A (one end on the side of the second storage battery 32) is connected to a connection point P13 on the 2A electrical path 2A between the 2A switch SW2a and the positive terminal of the second storage battery 32. From another perspective, one end of the 2A electrical path 2A (one end on the side of the second storage battery 32) is connected to a connection point P13 on the 3A electrical path 3A between the 3A switch SW3a and the positive terminal of the second storage battery 32. That is, the electrical path from the connection point P13 to the positive terminal of the second storage battery 32 is shared between the 2A electrical path 2A and the 3A electrical path 3A, and is part of both the 2A electrical path 2A and the 3A electrical path 3A. Hereinafter, the electrical path from the connection point P13 to the positive terminal of the second storage battery 32 may be referred to as a common path L10.

[0039] The power supply system 30 includes a third-B switch SW3b provided on a third-B electrical path 3B that connects the negative terminal of the second storage battery 32 and the low-voltage ground line L2. The third-B switch SW3b switches between energization and de-energization between the negative terminal of the second storage battery 32 and the low-voltage ground line L2, which in this embodiment is the third-B electrical path 3B.

[0040] In this embodiment, the switches SW1a, SW1b, SW1c, SW1d, SW1e, SW2a, SW2b, SW3a, and SW3b (hereinafter sometimes collectively referred to as switches SW) are mechanical relays. When turned off, each switch SW blocks bidirectional current flow, and when turned on, allows bidirectional current flow. Note that each switch SW is not limited to a mechanical relay and may be, for example, a semiconductor switching element.

[0041] The power supply system 30 also includes various sensors. As shown in Fig. 1, the first A electrical path 1A includes a first current sensor A11. The first D electrical path 1D includes a second current sensor A12. The second A electrical path 2A includes a third current sensor A13.

[0042] The arrangement of the third current sensor A13 will now be described in detail. The third current sensor A13 is arranged on the electrical path between the connection point P13 and the positive terminal of the second storage battery 32, i.e., on the common path L10. Therefore, the third current sensor A13 can measure the current flowing through the second-A electrical path 2A and the current flowing through the third-A electrical path 3A.

[0043] The measurement range of the third current sensor A13 is changeable. Specifically, the measurement range of the third current sensor A13 when measuring the current flowing through the second-A electrical path 2A and the measurement range when measuring the current flowing through the third-A electrical path 3A are changeable. The measurement range when measuring the current flowing through the second-A electrical path 2A is set to a wider measurable range than the measurement range when measuring the current flowing through the third-A electrical path 3A. For example, the measurement range when measuring the current flowing through the second-A electrical path 2A is set to a range that allows appropriate measurement of the current flowing through the second-A electrical path 2A (e.g., 100 A to 200 A). Similarly, the measurement range when measuring the current flowing through the third-A electrical path 3A is set to a range that allows appropriate measurement of the current flowing through the third-A electrical path 3A (e.g., several tens of amperes).

[0044] In addition, the resolution of the third current sensor A13 is changed in accordance with the change in the measurement range. Specifically, when measuring the current flowing through the 3A electrical path 3A, the resolution is changed to be smaller (finer) than when measuring the current flowing through the 2A electrical path 2A, so that even small values ​​can be detected with high accuracy.

[0045] A first voltage sensor V1 is provided between the high-voltage power supply line H1 and the high-voltage ground line L1 to measure the voltage (potential difference) therebetween. The first voltage sensor V1 also measures the terminal voltage of the inverter-side smoothing capacitor 21. A second voltage sensor V2 is provided between the first-D electrical path 1D and the high-voltage ground line L1 to measure the voltage (potential difference) therebetween. The second voltage sensor V2 also measures the terminal voltage of the neutral-point-side smoothing capacitor C1. A third voltage sensor V3 is provided between the low-voltage power supply line H2 and the low-voltage ground line L2 (second ground SG) to measure the voltage (potential difference) therebetween.

[0046] The power supply system 30 also includes a control device 100. The control device 100 is mainly configured with a microcomputer 101, which includes a CPU, RAM, ROM, etc. The functions provided by the microcomputer 101 can be provided by software stored in a physical memory device and a computer executing the software, by software alone, by hardware alone, or a combination thereof. For example, if the microcomputer 101 is provided by a hardware electronic circuit, the functions can be provided by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer 101 executes a program stored in a non-transitory tangible storage medium serving as a storage unit of the microcomputer 101. The program includes, for example, programs for the processes shown in FIGS. 9 and 12, which will be described later. Execution of the program results in the execution of a method (process) corresponding to the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a communication network such as the Internet, for example, via OTA (Over The Air) or the like.

[0047] Information (detected values) from various sensors are input to the control device 100. The various sensors include, for example, the current sensors A11 to A13 and voltage sensors V1 to V3 described above. In addition, although not shown, the various sensors include, for example, voltage sensors (voltage monitoring sensors) that detect the terminal voltages (and / or cell voltages) of the storage batteries 31, 32, and 33, current sensors that detect the currents flowing through the storage batteries 31, 32, and 33, rotation angle sensors that detect the rotation angle (electrical angle) of the rotor, and phase current sensors that detect the phase currents flowing through the armature windings 11 of each phase.

[0048] The control device 100 performs various processes according to a program based on information such as detected values ​​input from various sensors. The various processes include, for example, a process for controlling the inverter 20. Specifically, the control device 100 performs switching control of the switches SWH and SWL constituting the inverter 20 to feedback control the control amount of the motor 10 to a command value based on the detected values ​​of the sensors. The control amount is, for example, torque. In each phase, the upper arm switch SWH and the lower arm switch SWL are alternately turned on. This feedback control transmits the rotational power of the rotor to the drive wheels, causing the vehicle to run. Therefore, the control device 100 functions as an inverter control unit.

[0049] Furthermore, as described above, the control device 100 performs processing related to voltage conversion by controlling the DC-DC converter 70. Therefore, the control device 100 has a function as a voltage control unit.

[0050] The control device 100 is also configured to be able to control the on / off of each switch SW of the power supply system 30. Therefore, the control device 100 has a function as a switch control unit. Here, an example of how the control device 100 switches the on / off state of each switch SW of the power supply system 30 in this embodiment will be described.

[0051] First, with reference to Figures 2 to 8, we will explain how the on / off state is switched when the vehicle is started from a stopped state. In Figures 2 to 8, the flow of current is indicated by dashed lines. Also, as a premise, while the vehicle is stopped, the on / off state of each switch SW is as shown in Figure 2. Here, "while the vehicle is stopped" refers to a period when, for example, the ignition switch is off, the vehicle has been stopped for a predetermined period of time or more, or the shift lever is in park.

[0052] As shown in FIG. 2, while the vehicle is stopped, the control device 100 connects only one storage battery (second storage battery 32) among the storage batteries 31 to 33 included in the power supply system 30 to the low-voltage power supply line H2 and the low-voltage ground line L2.

[0053] Specifically, as shown in Fig. 2, the control device 100 turns off the first A switch SW1a, the first B switch SW1b, the first C switch SW1c, the first D switch SW1d, the first E switch SW1e, the second A switch SW2a, and the second B switch SW2b, and turns on the third A switch SW3a and the third B switch SW3b. In the connection state of Fig. 2, low-voltage power is supplied from the second storage battery 32 to the low-voltage load 72 (low-voltage circuit 76) via the low-voltage power supply line H2. Note that, as shown in Fig. 2, power is not supplied to the high-voltage load 71 from the first storage battery 31 or the like via the high-voltage power supply line H1.

[0054] When the vehicle is started while stopped, the control device 100 connects some of the storage batteries 31 to 33 of the power supply system 30 (the second storage battery 32) to the low-voltage power supply line H2, while connecting some or all of the remaining storage batteries (the first storage battery 31 in this embodiment) to the high-voltage power supply line H1. Here, the timing at which the vehicle starts refers to, for example, the timing at which the ignition switch is turned on, the timing at which the brake is released, the timing at which the shift lever is put into drive, etc. Alternatively, the timing at which the vehicle starts may be the timing at which a predetermined vehicle load (such as the operation of a sliding door or key) is started.

[0055] Specifically, to prevent inrush current, the control device 100 turns on the pre-charge switch Pre_P, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e, and charges the inverter-side smoothing capacitor 21 via the inverter 20. Specifically, charging is performed until the voltage across the inverter-side smoothing capacitor 21 reaches a voltage equivalent to the voltage across the terminals of the first storage battery 31 (400 V).

[0056] Thereafter, the control device 100 turns on the first A switch SW1a and turns off the pre-charge switch Pre_P. That is, as shown in Fig. 3, the control device 100 turns off the first B switch SW1b, the second A switch SW2a, and the second B switch SW2b, and turns on the first A switch SW1a, the first C switch SW1c, the first D switch SW1d, the first E switch SW1e, the third A switch SW3a, and the third B switch SW3b. In the connection state of Fig. 3, the second storage battery 32 is connected between the low-voltage power supply line H2 and the low-voltage ground line L2, and the first storage battery 31 is connected between the high-voltage power supply line H1 and the neutral point of the motor 10.

[0057] 3, the high-voltage ground line L1 and the low-voltage ground line L2 are insulated from each other. As a result, high-voltage power is supplied from the first storage battery 31 to the high-voltage load 71 via the high-voltage power supply line H1, while low-voltage power is supplied from the second storage battery 32 to the low-voltage load 72 via the low-voltage power supply line H2. In other words, the current flow between the first storage battery 31 and the second storage battery 32 is cut off, and the high-voltage power of the first storage battery 31 is not supplied to the low-voltage load 72.

[0058] Next, as shown in FIG. 4, the control device 100 operates the DC-DC converter 70 to step down the input voltage to the DC-DC converter 70 and supplies the stepped down voltage to the low-voltage load 72 via the power transmission line L3.

[0059] After power is supplied from the DC-DC converter 70 to the low-voltage circuit 76, the control device 100 cuts off the current between the second storage battery 32 and the low-voltage power supply line H2 while maintaining the current between the first storage battery 31 and the high-voltage power supply line H1, as shown in Figure 5.

[0060] Specifically, as shown in Fig. 5, the control device 100 turns off the firstB switch SW1b, the secondA switch SW2a, the secondB switch SW2b, the thirdA switch SW3a, and the thirdB switch SW3b, and turns on the firstA switch SW1a, the firstC switch SW1c, the firstD switch SW1d, and the firstE switch SW1e. In the connection state of Fig. 5, the first storage battery 31 is connected between the high-voltage power supply line H1 and the neutral point of the motor 10, while current is cut off between the low-voltage power supply line H2 and the positive terminal of the second storage battery 32 and between the low-voltage ground line L2 and the negative terminal of the second storage battery 32. In other words, the second storage battery 32 is disconnected from the low-voltage circuit 76.

[0061] After the current flow between the second storage battery 32 and the low-voltage circuit 76 is interrupted, the control device 100 operates the motor 10 and the inverter 20 as a boost converter (boost chopper) to boost the applied voltage from the first storage battery 31 and charge the inverter-side smoothing capacitor 21 and the neutral-point-side smoothing capacitor C1. That is, the control device 100 functions the armature winding of the motor 10 as a boost chopper coil, the lower-arm switch SWL (or upper-arm switch SWH) of the inverter 20 as an input switch of the boost chopper, and the upper-arm diode DH (or lower-arm diode DL) of the inverter 20 as a freewheel diode of the boost chopper, thereby boosting the applied voltage. Therefore, in this embodiment, the motor 10 and the inverter 20 also function as a boost device.

[0062] At this time, the inverter side smoothing capacitor 21 is charged until its terminal voltage reaches 612 V, which corresponds to the voltage across both ends when the first storage battery 31 to the third storage battery 33 are connected in series, and the neutral side smoothing capacitor C1 is charged until its terminal voltage reaches 212 V, which corresponds to the voltage across both ends when the second storage battery 32 to the third storage battery 33 are connected in series.

[0063] After the charging is completed, the control device 100 connects all of the first to third storage batteries 31 to 33 included in the power supply system 30 to the high-voltage power supply line H1, as shown in Fig. 6. Specifically, as shown in Fig. 6, the control device 100 turns off the firstB switch SW1b, the thirdA switch SW3a, and the thirdB switch SW3b, and turns on the firstA switch SW1a, the firstC switch SW1c, the firstD switch SW1d, the firstE switch SW1e, the secondA switch SW2a, and the secondB switch SW2b.

[0064] 6, the first storage battery 31, the third storage battery 33, and the second storage battery 32 are connected in series between the high-voltage power supply line H1 and the high-voltage ground line L1. That is, high-voltage (400V+200V+12V) electric power is supplied from the second series-connected assembly 50 of the first storage battery 31, the third storage battery 33, and the second storage battery 32 to the high-voltage load 71 of the high-voltage circuit 75 via the high-voltage power supply line H1. This allows high-voltage electric power to be supplied to the motor 10 and the high-voltage load 71, enabling the vehicle to be driven appropriately.

[0065] As shown in Fig. 6, the power supplied to the high-voltage circuit 75 is stepped down via the DC-DC converter 70 and supplied to the low-voltage load 72. The inverter-side smoothing capacitor 21 is charged until the voltage across its terminals reaches 612 V, and the neutral-side smoothing capacitor C1 is charged until the voltage across its terminals reaches 212 V. Therefore, even when the connection state is switched to that shown in Fig. 6, it is possible to prevent the current flow from becoming unstable due to a voltage difference.

[0066] Thereafter, the control device 100 switches the first D switch SW1d from on to off, and operates the motor 10 and the inverter 20 to discharge the charged voltage of the neutral point side smoothing capacitor C1, as shown in Fig. 7. After the discharge is completed, the control device 100 switches the first E switch SW1e from on to off, as shown in Fig. 8.

[0067] As described above, in the first embodiment, the first A switch SW1a (or pre-charge switch Pre_P), the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the first switch unit that switches between energization and de-energization between the first storage battery 31 and the high-voltage circuit 75. Hereinafter, in the first embodiment, the first A switch SW1a, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e may be simply referred to as the first switch unit.

[0068] In the first embodiment, the second A switch SW2a and the second B switch SW2b correspond to a second switch unit that switches between energization and de-energization between the first storage battery 31 and the second storage battery 32. Hereinafter, in the first embodiment, the second A switch SW2a and the second B switch SW2b may be simply referred to as the second switch unit.

[0069] In the first embodiment, the 3A switch SW3a and the 3B switch SW3b correspond to a third switch unit that switches between energization and de-energization between the second storage battery 32 and the low-voltage circuit 76. Hereinafter, in the first embodiment, the 3A switch SW3a and the 3B switch SW3b may be referred to as a unit third switch unit.

[0070] In addition, in the first embodiment, the 1A switch SW1a corresponds to the 1X switch that switches between energizing and de-energizing between the positive terminal of the first storage battery 31 and the high-voltage power supply line H1, and the 1A electrical path 1A that connects between the positive terminal of the first storage battery 31 and the high-voltage power supply line H1 corresponds to the 1X electrical path.

[0071] In addition, in the first embodiment, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to a first Y switch that switches between energization and de-energization between the negative terminal of the first storage battery 31 and the high-voltage ground line L1, and the electrical path between the negative terminal of the first storage battery 31 and the high-voltage ground line L1 corresponds to the first Y electrical path.

[0072] In addition, in the first embodiment, the second A switch SW2a corresponds to a second X switch that switches between energizing and de-energizing the second storage battery 32 and the first storage battery 31, and the second A electrical path 2A between the second storage battery 32 and the first storage battery 31 corresponds to the second X electrical path.

[0073] In the first embodiment, the secondB switch SW2b corresponds to a second Y switch that switches between energization and de-energization between the high-voltage ground line L1 and a terminal (negative terminal) opposite the secondA switch SW2a among both ends of the second storage battery 32. In the first embodiment, the secondB electrical path 2B between the high-voltage ground line L1 and a terminal (negative terminal) opposite the secondA switch SW2a among both ends of the second storage battery 32 corresponds to the second Y electrical path.

[0074] In addition, in the first embodiment, the 3A switch SW3a corresponds to a 3X switch that switches between energizing and de-energizing between the positive terminal of the second storage battery 32 and the low-voltage power supply line H2, and the 3A electrical path 3A that connects the positive terminal of the second storage battery 32 and the low-voltage power supply line H2 corresponds to the 3X electrical path.

[0075] In addition, in the first embodiment, the third B switch SW3b corresponds to a third Y switch that switches between energization and de-energization between the negative terminal of the second storage battery 32 and the low-voltage ground line L2, and the electrical path between the negative terminal of the second storage battery 32 and the low-voltage ground line L2 corresponds to the third Y electrical path.

[0076] In addition, in the first embodiment, the second A switch SW2a, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to a neutral point connection switch unit that switches between energization and de-energization between the neutral point of the motor 10 and either or both of the first storage battery 31 and the second storage battery 32.

[0077] Next, the switching of the on / off state when the vehicle is stopped from being started will be described with reference to Figures 2 to 8. The switching of the on / off state when the vehicle is stopped from being started from being started is basically the opposite of the transition of the on / off state when the vehicle is started from being stopped. For this reason, the following will be a simplified explanation.

[0078] During vehicle startup, the connection state shown in Fig. 8 is established as described above. That is, the control device 100 connects the first storage battery 31, the third storage battery 33, and the second storage battery 32 in series between the high-voltage power supply line H1 and the high-voltage ground line L1. Meanwhile, the power supply system 30 and the low-voltage circuit 76 are not directly connected, but the high-voltage power is stepped down by the DC-DC converter 70 and supplied to the low-voltage load 72.

[0079] When the vehicle is stopped during startup, the control device 100 first switches the first E switch SW1e from OFF to ON as shown in Fig. 7. The timing at which the vehicle is stopped is, for example, when the ignition switch is turned OFF or when the shift lever is put into park.

[0080] After the first E switch SW1e is switched on, the motor 10 and the inverter 20 are operated to charge the inverter-side smoothing capacitor 21. Then, the control device 100 charges the inverter-side smoothing capacitor 21 until the voltage across the terminals of the inverter-side smoothing capacitor 21 reaches a voltage equivalent to the voltage across the terminals of the first series-connected body 40 (for example, 212 V).

[0081] After the charging is completed, the control device 100 switches the first D switch SW1d from off to on, as shown in Fig. 6. Thereafter, the control device 100 switches the second A switch SW2a and the second B switch SW2b from on to off, as shown in Fig. 5, to cut off the current between the first storage battery 31 and the second storage battery 32 and between the second storage battery 32 and the low-voltage ground line L2 while maintaining the current between the first storage battery 31 and the high-voltage power supply line H1. In other words, the second storage battery 32 is disconnected from the high-voltage circuit 75.

[0082] After the current flow between the second storage battery 32 and the high-voltage circuit 75 is cut off, the control device 100 operates the motor 10 and the inverter 20 to discharge the inverter-side smoothing capacitor 21. At this time, the voltage across the terminals of the inverter-side smoothing capacitor 21 is maintained for a certain period of time, and then the voltage is gradually discharged (stepped down) until it reaches a voltage (400 V) equivalent to the voltage across the terminals of the first storage battery 31.

[0083] Furthermore, the control device 100 discharges the neutral point side smoothing capacitor C1 by operating the motor 10 and the inverter 20. At this time, the neutral point side smoothing capacitor C1 continues to discharge until the voltage across its terminals becomes zero.

[0084] After discharging, the control device 100 switches the third-A switch SW3a and the third-B switch SW3b from off to on, as shown in Fig. 4. As a result, the second storage battery 32 is connected between the low-voltage power supply line H2 and the low-voltage ground line L2, while the first storage battery 31 remains connected between the high-voltage power supply line H1 and the neutral point of the motor 10. This enables the second storage battery 32 to supply low-voltage power to the low-voltage load 72 (low-voltage circuit 76).

[0085] Thereafter, as shown in Fig. 3, the control device 100 stops the operation of the DC-DC converter 70 and stops the power supply from the DC-DC converter 70 to the low-voltage load 72. As a result, low-voltage power is supplied from the second storage battery 32 to the low-voltage load 72. Then, as shown in Fig. 2, the control device 100 switches the first A switch SW1a, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e from on to off. In addition, the control device 100 operates the motor 10 and the inverter 20 to discharge the inverter-side smoothing capacitor 21 and set the inter-terminal voltage to zero.

[0086] 2, only the second storage battery 32 is connected to the low-voltage power supply line H2 and the low-voltage ground line L2, and is in an on-off state while the vehicle is stopped. In this state, power is supplied from the second storage battery 32 to the low-voltage load 72.

[0087] The power supply system 30 of this embodiment is configured to be connectable to both the high-voltage circuit 75 and the low-voltage circuit 76 and to supply power to both. Therefore, if any of the switches SW has an on-failure (welding), the high-voltage circuit 75 and the low-voltage circuit 76 are directly connected, making it impossible to cut off the current flow between the first storage battery 31 and the second storage battery 32. In other words, there is a possibility that the high-voltage first storage battery 31 or the like will be connected to the low-voltage load 72, or that the first ground FG and the second ground SG will be connected. Therefore, it is necessary to turn each switch SW on and off and determine whether it operates normally, that is, to determine whether each switch SW has a fault.

[0088] However, as described above, the power supply system 30 is configured to be connectable to both the high-voltage circuit 75 and the low-voltage circuit 76. Therefore, it is necessary to appropriately turn on and off each switch SW at appropriate timing during failure determination so that insulation between the first ground FG and the second ground SG is maintained (the high-voltage circuit 75 and the low-voltage circuit 76 are not connected). Therefore, in this embodiment, failure determination of each switch SW is performed at the timing described below. Below, failure determination of each switch SW performed when the vehicle is started and stopped will be described in detail. First, the startup process will be described.

[0089] 9 is a flowchart of the startup process that the control device 100 executes at predetermined intervals while the vehicle is stopped. As described above, when the vehicle is stopped, the connection state is as shown in FIG. 2, with the first switch unit and the second switch unit turned off and the third switch unit turned on. In other words, only the second storage battery 32 is connected to the low-voltage power supply line H2.

[0090] The control device 100 determines whether the vehicle has started while the vehicle is stopped (step S101). If the result of this determination is positive, the control device 100 connects the second storage battery 32 to the low-voltage power supply line H2 while connecting the first storage battery 31 to the high-voltage power supply line H1 (step S102), as shown in FIG. 3. That is, as described above, the control device 100 turns on the third switch unit, keeps the second switch unit off, and switches on the first switch unit. As a result, the first storage battery 31 is connected to the high-voltage circuit 75 while the second storage battery 32 remains connected to the low-voltage circuit 76.

[0091] Since the second switch unit (the second A switch SW2a and the second B switch SW2b) is turned off, the current is cut off between the first storage battery 31 and the second storage battery 32, and between the high-voltage circuit 75 and the low-voltage circuit 76. In other words, the high-voltage power is not directly supplied to the low-voltage circuit 76.

[0092] Furthermore, when the first switch unit is switched on in step S102, the control device 100 inputs and stores detection values ​​of various sensors. After switching, the control device 100 determines whether or not there is a fault in the first switch unit based on the stored detection values ​​of the various sensors (step S103). In step S103, the control device 100 performs a fault determination for the first switch unit by determining whether or not current is flowing normally in the first-A electrical path 1A from the detection value of the first current sensor A11 when the first switch unit is switched on in step S102.

[0093] For example, if the detection value of the first current sensor A11 is not zero (or is not within an error range close to zero; the same applies below) before the first switch unit is switched on (despite being off), i.e., if an abnormal current is measured in the first-A electrical path 1A, the control device 100 determines that the first switch unit is faulty. Furthermore, for example, if the detection value of the first current sensor A11 is not a value equal to or greater than a threshold value even after the first switch unit is switched on, i.e., if no current flows in the first-A electrical path 1A, the control device 100 determines that the first switch unit is faulty. On the other hand, if the detection value of the first current sensor A11 changes from zero to a current value equal to or greater than the threshold value as a result of the first switch unit being switched on, the control device 100 determines that the first switch unit is normal (not faulty).

[0094] If the control device 100 determines that the first switch unit has a fault as a result of the fault determination in step S103 (step S103: Yes), it performs processing to deal with the abnormality in the power supply system 30 (step S104). In step S104, for example, it performs processing to notify that there is an abnormality in the power supply system 30 and to notify that it cannot be started up properly. It also performs processing related to fail-safe, such as switching all switches SW off to ensure safety. Thereafter, the control device 100 ends (interrupts) the startup processing.

[0095] On the other hand, if the control device 100 determines that there is no fault in the first switch unit (step S103: No), it operates the inverter 20, etc. to supply power from the first storage battery 31 to the high-voltage circuit 75, and charges the inverter-side smoothing capacitor 21 until the terminal voltage reaches 400 V (step S105).

[0096] After the inverter-side smoothing capacitor 21 has been charged, the control device 100 operates the DC-DC converter 70 to step down the input voltage to the DC-DC converter 70 and supply it to the low-voltage load 72 (low-voltage circuit 76) via the power transmission line L3 (step S106), as shown in Fig. 4. At this time, the control device 100 controls the DC-DC converter 70 to step down the voltage to a voltage slightly higher than the terminal voltage (12 V) of the second storage battery 32, for example, to 14 V. As a result, when power is supplied from the DC-DC converter 70 to the low-voltage circuit 76, a current flows to the second storage battery 32, and the second storage battery 32 is charged.

[0097] 5, the control device 100 turns off the third switch unit while keeping the second switch unit turned off, thereby interrupting the flow of electricity between the second storage battery 32 and the low-voltage power supply line H2 (step S107). In addition, when switching off the third switch unit in step S107, the control device 100 inputs and stores the detection values ​​of the various sensors.

[0098] After the switching, the control device 100 determines whether or not there is a failure in the third switch unit based on the stored detection values ​​of the various sensors (step S108). In step S108, the control device 100 determines whether or not the current flow through the 3A electrical path 3A is normally interrupted based on the detection value of the third current sensor A13 when the third switch unit is switched in step S107, thereby determining whether or not there is a failure in the third switch unit.

[0099] An example of a method for determining whether or not there is a failure in the third switch unit in step S108 will now be described in detail with reference to Fig. 10. Fig. 10 shows the on / off states of the third A switch SW3a and the third B switch SW3b and the corresponding detection values ​​of the third current sensor A13 under normal conditions.

[0100] As a premise, when determining whether the third switch unit has a fault, the control device 100 switches the measurement range and resolution of the third current sensor A13 to the measurement range and resolution for measuring the current of the third-A electrical path 3A. That is, the control device 100 narrows the measurement range and reduces the resolution of the third current sensor A13. Also, as described in step S106, in this embodiment, the supply voltage from the DC-DC converter 70 is a voltage (14 V) that is slightly higher than the inter-terminal voltage (12 V) of the second storage battery 32.

[0101] 10, when the third switch unit (the third A switch SW3a and the third B switch SW3b) is turned on, a current flows from the DC-DC converter 70 to the second storage battery 32, and the second storage battery 32 is charged. At this time, the detection value of the third current sensor A13 depends on the amount of current output from the DC-DC converter 70, but should be at least a value greater than 0 (for example, several tens of amperes). Therefore, if the detection value of the third current sensor A13 is zero even though the third switch unit is turned on, the control device 100 determines that there is a fault in the third switch unit.

[0102] In addition, when it is written "Depends on DCDC" in the figure, it means that when the supply voltage from the DCDC converter 70 is higher than the terminal voltage of the second storage battery 32, the detection value of the third current sensor A13 depends on the amount of current output from the DCDC converter 70, and when it is equal to or lower than the terminal voltage of the second storage battery 32, the detection value of the third current sensor A13 depends on the amount of current from the second storage battery 32.

[0103] Furthermore, in step S107, the control device 100 turns off the third-A switch SW3a from the ON state, and then turns off the third-B switch SW3b to turn off the third switch unit. Therefore, as shown in the middle part of FIG. 10, if the detection value of the third current sensor A13 is not zero when the third-A switch SW3a is OFF and the third-B switch SW3b is ON, the control device 100 determines that the third-A switch SW3a has a fault; if the detection value is zero, the control device 100 determines that the third-A switch SW3a does not have a fault. If it is determined that the third-A switch SW3a has a fault, the control device 100 determines that the third switch unit has a fault; if it is determined that the third-A switch SW3a does not have a fault, the control device 100 determines that the third switch unit does not have a fault. Note that this fault determination method is merely an example, and variations of the fault determination method will be described later.

[0104] If the determination result in step S108 is positive (step S108: Yes), the control device 100 proceeds to the process of step S104, and as described above, performs the process to deal with the abnormality in the power supply system 30 (step S104). Thereafter, the control device 100 ends (interrupts) the startup process.

[0105] On the other hand, if the control device 100 determines that the third switch unit is not faulty (step S108: No), the control device 100 operates the motor 10 and the inverter 20 to charge the inverter-side smoothing capacitor 21 and the neutral-point-side smoothing capacitor C1 (step S109). Specifically, charging is performed until the voltage across the inverter-side smoothing capacitor 21 reaches 612 V and the voltage across the neutral-point-side smoothing capacitor C1 reaches 212 V.

[0106] 6, the control device 100 turns on the second switch unit while keeping the third switch unit off, and connects all of the first to third storage batteries 31 to 33 included in the power supply system 30 to the high-voltage power supply line H1 (step S110). When turning on the second switch unit in step S110, the control device 100 also inputs and stores detection values ​​of various sensors.

[0107] After switching, the control device 100 determines whether or not there is a failure in the second switch unit based on the stored detection values ​​of the various sensors (step S111). In step S111, the control device 100 determines whether or not a current flows normally in the secondA electrical path 2A from the detection value of the third current sensor A13 when the second switch unit is switched in step S110, thereby determining whether or not there is a failure in the second switch unit.

[0108] An example of the method for determining whether or not a second switch unit has failed in step S111 will now be described in detail with reference to FIG. 11. FIG. 11 shows the on / off states of the second A switch SW2a and the second B switch SW2b under normal conditions, and the corresponding detection values ​​of various sensors. When determining whether or not a second switch unit has failed, the control device 100 first switches the measurement range and resolution of the third current sensor A13 to those for measuring the current in the second A electrical path 2A. In other words, the control device 100 widens the measurement range and increases the resolution of the third current sensor A13.

[0109] At this time, as shown in the upper part of Figure 11, if the detection value of the third current sensor A13 is not zero (or is not within an error range close to zero, and the same applies below) even though the second switch unit is turned off, the control device 100 determines that there is a fault in the second switch unit.

[0110] Furthermore, in step S110, the control device 100 turns on the second A switch SW2a, and then turns on the second B switch SW2b, thereby turning on the second switch unit. Therefore, as shown in the middle part of Fig. 11, if the detection value of the third current sensor A13 is not zero when the second A switch SW2a is on and the second B switch SW2b is off, the control device 100 determines that there is a fault in the second switch unit.

[0111] Furthermore, if the detection value of the third current sensor A13 is equal to or greater than a predetermined threshold when the second A switch SW2a and the second B switch SW2b are both on and it is determined that current is flowing normally, the control device 100 determines that there is no fault in the second switch unit. On the other hand, if the detection value of the third current sensor A13 is zero even though the second switch unit is on, it determines that there is a fault in the second switch unit. Note that this fault determination method is just one example, and modified examples of the fault determination method will be described later.

[0112] If it is determined that the second switch unit has a failure (step S111: Yes), the control device 100 proceeds to the process of step S104, and as described above, performs the process to deal with the abnormality in the power supply system 30 (step S104). Thereafter, the control device 100 ends (interrupts) the startup process.

[0113] On the other hand, if it is determined that there is no failure in the second switch section (step S111: No), the control device 100 turns off the first D switch SW1d, operates the motor 10 and the inverter 20, and discharges the charged voltage of the neutral point side smoothing capacitor C1 (step S112).

[0114] After the discharge is completed, the control device 100 switches the first E switch SW1e from on to off (step S113) as shown in FIG. 8, and ends the startup process. When the startup process is completed, as shown in FIG. 8, high-voltage power is supplied from the second series-connected body 50, in which all of the storage batteries 31, 32, and 33 are connected in series, to the high-voltage load 71 of the high-voltage circuit 75 via the high-voltage power supply line H1. This allows high-voltage power to be supplied to the motor 10 and the high-voltage load 71, making it possible to drive the vehicle appropriately. Furthermore, as shown in FIG. 8, the power supplied to the high-voltage circuit 75 is stepped down via the DC-DC converter 70 and supplied to the low-voltage load 72 as well, allowing the low-voltage load 72 to operate appropriately.

[0115] Next, the failure determination of each switch SW performed when the vehicle is stopped will be described in detail with reference to Fig. 12. Fig. 12 is a flowchart of the stop processing performed by the control device 100 at predetermined intervals while the vehicle is running. As described above, when the vehicle is started, the connection state is as shown in Fig. 8, and all of the storage batteries 31, 32, and 33 are connected in series to the high-voltage circuit 75. In addition, low-voltage power is supplied to the low-voltage load 72 via the DC-DC converter 70.

[0116] The control device 100 first determines whether the vehicle is stopped (step S201). If the result of this determination is negative, the control device 100 terminates the stopping process. On the other hand, if the result of this determination is positive, the control device 100 switches on the first E switch SW1e, as shown in FIG. 7, and then operates the motor 10 and the inverter 20 to charge the neutral point side smoothing capacitor C1 (step S202).

[0117] After charging is completed, the control device 100 switches the first D switch SW1d from OFF to ON (step S203), as shown in Fig. 6. Thereafter, as shown in Fig. 5, the control device 100 switches the second switch unit OFF while keeping the third switch unit OFF, thereby interrupting the flow of electricity between the first storage battery 31 and the second storage battery 32 and between the second storage battery 32 and the low-voltage ground line L2 (step S204). That is, the second storage battery 32 is disconnected from the high-voltage circuit 75. Furthermore, when switching the second switch unit OFF in step S204, the control device 100 inputs and stores detection values ​​of various sensors.

[0118] After the switching, the control device 100 determines whether or not there is a failure in the second switch unit based on the stored detection values ​​of the various sensors (step S205). In step S205, the control device 100 determines whether or not the current flow through the secondA electrical path 2A is properly interrupted based on the detection value of the third current sensor A13 when the second switch unit is switched, thereby performing a failure determination for the second switch unit.

[0119] An example of a method for determining whether the second switch unit has a fault in step S205 will now be described in detail with reference to Fig. 11. It should be noted that, as a premise, when determining whether the second switch unit has a fault, i.e., before starting step S204, the control device 100 switches the measurement range and resolution of the third current sensor A13 to the measurement range and resolution for measuring the current in the second electrical path 2A. That is, the control device 100 widens the measurement range and increases the resolution of the third current sensor A13.

[0120] At this time, as shown in the lower part of Figure 11, if the detection value of the third current sensor A13 is zero (or within an error range close to zero, and so on) even though the second switch unit is on, the control device 100 determines that there is a fault in the second switch unit.

[0121] Then, in step S204, from a state in which the second switch unit is on, the control device 100 turns off the secondB switch SW2b and then turns off the secondA switch SW2a, thereby turning off the second switch unit. Therefore, as shown in the middle part of Fig. 11, if the detection value of the third current sensor A13 in a state in which the secondA switch SW2a is on and the secondB switch SW2b is off is not zero, the control device 100 determines that there is a fault in the second switch unit.

[0122] 11, if the detection value of the third current sensor A13 is zero when the second A switch SW2a and the second B switch SW2b are off and it is determined that the current has been normally interrupted, the control device 100 determines that there is no fault in the second switch unit. On the other hand, if the detection value of the third current sensor A13 is not zero even when the second switch unit is off, the control device 100 determines that there is a fault in the second switch unit. Note that this fault determination method is just one example, and modified examples of the fault determination method will be described later.

[0123] If it is determined that the second switch unit has a failure (step S205: Yes), the control device 100 performs processing to deal with the abnormality in the power supply system 30 (step S206). The processing in step S206 is the same as that in step S104. Thereafter, the control device 100 ends (interrupts) the shutdown processing.

[0124] On the other hand, if it is determined that there is no failure in the second switch unit (step S205: No), the control device 100 operates the motor 10 and the inverter 20 to discharge the inverter-side smoothing capacitor 21 and the neutral point-side smoothing capacitor C1 (step S207). At this time, the control device 100 operates the motor 10 and the inverter 20 to gradually discharge the inverter-side smoothing capacitor 21 until the voltage reaches a voltage equivalent to the inter-terminal voltage of the first storage battery 31.

[0125] After the discharge, the control device 100 turns on the third switch unit while keeping the second switch unit off, and connects the second storage battery 32 between the low-voltage power supply line H2 and the low-voltage ground line L2 (step S208), as shown in Fig. 4. This allows low-voltage power from the second storage battery 32 to be supplied to the low-voltage load 72. When the third switch unit is turned on in step S208, the control device 100 also inputs and stores detection values ​​of various sensors.

[0126] After the switching, the control device 100 determines whether or not there is a failure in the third switch unit based on the stored detection values ​​of the various sensors (step S209). In step S209, the control device 100 determines whether or not a normal current flows in the third-A electrical path 3A from the detection value of the third current sensor A13 when the third switch unit is switched in step S208, thereby determining whether or not there is a failure in the third switch unit.

[0127] An example of a method for determining whether or not there is a failure in the third switch unit in step S209 will now be described in detail with reference to Fig. 10. Fig. 10 shows the on / off states of the third A switch SW3a and the third B switch SW3b and the corresponding detection values ​​of the third current sensor A13 under normal conditions.

[0128] It is assumed that when determining whether the third switch unit has a fault, i.e., before performing step S208, the control device 100 switches the measurement range and resolution of the third current sensor A13 to the measurement range and resolution for measuring the current in the third-A electrical path 3A. That is, the control device 100 narrows the measurement range and reduces the resolution of the third current sensor A13. In addition, in this embodiment, the supply voltage from the DC-DC converter 70 is a voltage (14 V) slightly higher than the inter-terminal voltage (12 V) of the second storage battery 32.

[0129] As shown in the lower part of Figure 10, if the detection value of the third current sensor A13 is not zero (or is not within an error range close to zero, and the same applies below) even though the third switch section (third A switch SW3a and third B switch SW3b) is turned off, the control device 100 determines that there is a fault in the third switch section.

[0130] Furthermore, in step S208, the control device 100 turns on the thirdB switch SW3b from the state in which the third switch unit is off, and then turns on the thirdA switch SW3a, thereby turning on the third switch unit. Therefore, as shown in the middle part of Fig. 10, if the detection value of the third current sensor A13 is not zero in a state in which the thirdA switch SW3a is off and the thirdB switch SW3b is on, the control device 100 determines that there is a fault in the third switch unit.

[0131] 10, if the detection value of the third current sensor A13 is equal to or greater than a predetermined threshold when the third-A switch SW3a and the third-B switch SW3b are both on and the control device 100 determines that current is flowing normally, the control device 100 determines that there is no fault in the third switch unit. On the other hand, if the detection value of the third current sensor A13 is zero even when the third switch unit is on, the control device 100 determines that there is a fault in the third switch unit. Note that this fault determination method is just one example, and modified examples of the fault determination method will be described later.

[0132] If it is determined that the third switch unit has a failure (step S209: Yes), the control device 100 performs processing to deal with the abnormality in the power supply system 30, as described above (step S206). Thereafter, the control device 100 ends (interrupts) the shutdown processing.

[0133] On the other hand, when it is determined that there is no failure in the third switch unit (step S209: No), the control device 100 stops the operation of the DC-DC converter 70 and stops the power supply from the DC-DC converter 70 to the low-voltage load 72 (step S210), as shown in Fig. 3. As a result, the low-voltage load 72 is supplied with power from the second storage battery 32. Then, the control device 100 turns off the first switch unit while keeping the second switch unit turned off, and cuts off the current between the first storage battery 31 and the high-voltage circuit 75 (step S211).

[0134] Furthermore, in step S211, when switching the first switch unit to OFF, the control device 100 inputs and stores detection values ​​of various sensors. Then, after switching the first switch unit, the control device 100 determines whether or not there is a fault in the first switch unit based on the stored detection values ​​of the various sensors (step S212). In step S212, the control device 100 performs a fault determination for the first switch unit by determining whether or not the power supply to the firstA electrical path 1A is properly interrupted based on the detection value of the first current sensor A11 when the first switch unit is switched in step S211.

[0135] For example, if the detection value of the first current sensor A11 is zero before the first switch unit is switched off (despite being on), i.e., if no current is flowing through the firstA electrical path 1A, the control device 100 determines that the first switch unit is faulty. Also, for example, if the detection value of the first current sensor A11 does not become zero even after the first switch unit is switched off, i.e., if the current supply to the firstA electrical path 1A is not interrupted, the control device 100 determines that the first switch unit is faulty. On the other hand, if the detection value of the first current sensor A11 becomes zero as the first switch unit is switched off, the control device 100 determines that the first switch unit is normal (not faulty).

[0136] If it is determined that the first switch unit has a failure (step S212: Yes), the control device 100 performs processing to deal with the abnormality in the power supply system 30, as described above (step S206). Thereafter, the control device 100 ends (interrupts) the shutdown processing.

[0137] On the other hand, if it is determined that there is no failure in the third switch unit (step S212: No), the control device 100 operates the motor 10 and the inverter 20 to discharge the inverter-side smoothing capacitor 21 (step S213), and then ends the stop processing.

[0138] According to the first embodiment, the following effects are achieved.

[0139] When the second switch unit is turned off, cutting off the current between the first storage battery 31 and the second storage battery 32, and between the high-voltage circuit 75 and the low-voltage circuit 76, the control device 100 switches the on / off state of the first switch unit to determine whether the first switch unit has failed.

[0140] Specifically, in step S102 of the startup process, the control device 100 turns on the first switch unit (switches SW1a, SW1c, SW1d, and SW1e) while turning off the second switch unit. In the subsequent step S103, the control device 100 performs a failure determination for the first switch unit based on the detection value of the first current sensor A11 detected when the first switch unit is turned on. Furthermore, in step S211 of the stop process, the control device 100 turns off the first switch unit (switches SW1a, SW1c, SW1d, and SW1e) while turning off the second switch unit. In the subsequent step S212, the control device 100 performs a failure determination for the first switch unit based on the detection value of the first current sensor A11 detected when the first switch unit is turned off.

[0141] In addition, when the second switch unit is turned off, cutting off the current between the first storage battery 31 and the second storage battery 32, and between the high-voltage circuit 75 and the low-voltage circuit 76, the control device 100 switches the on / off state of the third switch unit to determine whether the third switch unit has failed.

[0142] Specifically, in step S107 of the startup process, the control device 100 turns off the third switch unit (switches SW3a and SW3b) while turning off the second switch unit. In the subsequent step S108, the control device 100 performs a failure determination for the third switch unit based on the detection value of the third current sensor A13 detected when the third switch unit is turned off. Furthermore, in step S208 of the startup process, the control device 100 turns on the third switch unit (switches SW3a and SW3b) while turning off the second switch unit. In the subsequent step S209, the control device 100 performs a failure determination for the third switch unit based on the detection value of the third current sensor A13 detected when the third switch unit is turned on.

[0143] As described above, when the second switch unit cuts off the current between the first storage battery 31 and the second storage battery 32 and between the high-voltage circuit 75 and the low-voltage circuit 76, switching the on / off state of the first switch unit or the third switch unit does not connect the high-voltage circuit 75 and the low-voltage circuit 76, preventing a high voltage from being applied to the low-voltage load 72. Therefore, it is possible to safely determine whether the first switch unit or the third switch unit has a fault.

[0144] When the third switch unit is turned off and the current flow between the second storage battery 32 and the low-voltage circuit 76 is cut off, the control device 100 switches the on / off state of the second switch unit to determine whether the second switch unit has failed.

[0145] Specifically, in step S110 of the startup process, the control device 100 turns on the second switch unit (switches SW2a and SW2b) while turning off the third switch unit. In the subsequent step S111, the control device 100 performs a failure determination for the second switch unit based on the detection value of the third current sensor A13 detected when the second switch unit is turned on.

[0146] In step S204 of the stop processing, the control device 100 turns off the second switch unit (switches SW2a and SW2b) while turning off the third switch unit. In the following step S205, the control device 100 performs a failure determination for the second switch unit based on the detection value of the third current sensor A13 detected when the second switch unit is turned off.

[0147] In this way, when the current between the second storage battery 32 and the low-voltage circuit 76 is cut off, even if the second switch unit is controlled to be on or off, the first storage battery 31 and the second storage battery 32 and the high-voltage circuit 75 and the low-voltage circuit 76 are not connected in the power supply system 30, and it is possible to prevent a high voltage from being applied to the low-voltage load 72. Therefore, it is possible to safely determine whether the second switch unit has failed.

[0148] As described in steps S102 to S103 and S208 to S212, the control device 100 determines whether the first switch unit has a fault while the second switch unit is turned off and the third switch unit is turned on. That is, when the power between the first storage battery 31 and the second storage battery 32 and between the high-voltage circuit 75 and the low-voltage circuit 76 is interrupted and power is being supplied from the second storage battery 32 to the low-voltage circuit 76, the control device 100 switches the on / off state of the first switch unit to determine whether the first switch unit has a fault. This prevents the power supply to the low-voltage load 72 from being interrupted when determining whether the first switch unit has a fault.

[0149] Furthermore, as described in steps S106 to S108 and S208 to S209, when the second switch unit is off, the control device 100 turns on the first switch unit to step down the high-voltage power using the DC-DC converter 70 and supply it to the low-voltage load 72, and during this time, performs a failure determination for the third switch unit. That is, the control device 100 performs a failure determination for the third switch unit when the power between the first storage battery 31 and the second storage battery 32 and between the high-voltage circuit 75 and the low-voltage circuit 76 are interrupted and low-voltage power is supplied to the low-voltage circuit 76 side via the DC-DC converter 70. This makes it possible to prevent interruption of the power supply to the low-voltage load 72 when a failure determination for the third switch unit is performed.

[0150] A portion of the 3A electrical path 3A connecting the positive terminal of the second storage battery 32 and the low-voltage power supply line H2 is shared with a portion of the electrical path that is energized when all of the storage batteries 31 to 33 are connected between the high-voltage power supply line H1 and the high-voltage ground line L1. Specifically, the electrical path from the positive terminal of the second storage battery 32 to the connection point P13 is a common path L10 that is shared between the 3A electrical path 3A and the 2A electrical path 2A. A third current sensor A13 (shared current sensor) is provided on this common path L10, and the control device 100 uses the detection values ​​of the third current sensor A13 when determining whether the second switch unit has a fault and when the third switch unit has a fault. This eliminates the need to use detection values ​​of separate current sensors when determining whether the second switch unit has a fault and when the third switch unit has a fault. For example, it is not necessary to provide separate current sensors for the 2A electrical path 2A and the 3A electrical path 3A. Therefore, the number of current sensors can be reduced and the wiring can be simplified.

[0151] The measurement range of the third current sensor A13 is changeable, and the resolution of the third current sensor A13 changes in accordance with the change in the measurement range. Specifically, the measurement range when measuring the current flowing through the second-A electrical path 2A is set to a wider measurable range than the measurement range when measuring the current flowing through the third-A electrical path 3A. For example, the measurement range when measuring the current flowing through the second-A electrical path 2A is set to a range that allows appropriate measurement of the current flowing through the second-A electrical path 2A (e.g., 100 A to 200 A). Furthermore, when measuring the current flowing through the third-A electrical path 3A, the resolution is changed to a smaller value, allowing measurement of smaller values, compared to when measuring the current flowing through the second-A electrical path 2A.

[0152] The control device 100 changes the measurement range and resolution of the third current sensor A13 depending on whether a failure in the second switch unit or the third switch unit is to be determined. For example, when determining a failure in the second switch unit, the control device 100 widens the measurement range of the third current sensor A13 to increase the resolution, and when determining a failure in the third switch unit, the control device 100 narrows the measurement range of the third current sensor A13 to decrease the resolution. This makes it possible to set the measurement range and resolution appropriate for the flowing current, enabling accurate current detection.

[0153] When each switch SW is switched and the number of storage batteries 31 to 33 connected to the high-voltage power supply line H1 is changed, the control device 100 controls the inverter 20 so that the voltage input to the motor 10 and the inverter 20 is increased or decreased by the motor 10 and the inverter 20, thereby adjusting the voltage between the terminals of the inverter-side smoothing capacitor 21.

[0154] Specifically, in step S109, which is performed after step S102 (first step) and before step S110 (second step), the control device 100 controls the inverter 20 to boost the voltage input from the first storage battery 31 to the inverter 20 by the motor 10 and the inverter 20. The control device 100 then applies the boosted voltage to the inverter-side smoothing capacitor 21, and boosts the terminal-to-terminal voltage of the inverter-side smoothing capacitor 21 until the terminal-to-terminal voltage of the inverter-side smoothing capacitor 21 corresponds to the terminal-to-terminal voltage of the second series-connected body 50. This prevents the supply voltage to the high-voltage circuit 75 from becoming unstable, even when the second switch unit is turned on and all the storage batteries 31 to 33 are connected in series to the high-voltage power supply line H1, thereby stabilizing the power supply to the high-voltage load 71. Furthermore, inrush current can be suppressed.

[0155] Furthermore, the control device 100 controls the motor 10 and the inverter 20 to boost the voltage across the neutral point side smoothing capacitor C1 until the voltage across the neutral point side smoothing capacitor C1 becomes equivalent to the voltage across the first series-connected body 40. This makes it possible to suppress inrush current during switching.

[0156] After steps S202 and S203 (fifth step) and before step S204 (sixth step), the control device 100 discharges the first smoothing capacitor using the inverter 20 and the motor 10, or controls the inverter 20 to boost the voltage input to the inverter 20 from the first storage battery 31 using the inverter 20 and the motor 10, apply the boosted voltage to the inverter-side smoothing capacitor 21, maintain the voltage across the inverter-side smoothing capacitor 21 for a certain period, and then gradually discharge (step down) the voltage. This prevents the voltage supplied to the high-voltage circuit 75 from becoming unstable even when the second switch unit is turned off, the second storage battery 32 and the third storage battery 33 are disconnected from the high-voltage power supply line H1, and all the storage batteries 31 to 33 are no longer connected in series. Furthermore, inrush current can be suppressed.

[0157] (Variation) A modified example (another example of the embodiment) in which the configuration of the above embodiment is partially changed will be described.

[0158] (Variation 1) A modification (modification 1) of the method for determining a failure of the third switch unit in the above embodiment will be described. Fig. 13 shows the on / off states of the third A switch SW3a and the third B switch SW3b and the corresponding detection values ​​of the third current sensor A13 under normal conditions.

[0159] First, a first modification of step S108 will be described. As shown in the upper part of Fig. 13, when the third switch unit (the third A switch SW3a and the third B switch SW3b) is turned on, a current flows from the DC-DC converter 70 to the second storage battery 32, and the second storage battery 32 is charged. Therefore, if the detection value of the third current sensor A13 is zero even though the third switch unit is turned on, the control device 100 determines that there is a fault in the third switch unit.

[0160] In addition, in Modification 1, when the third switch unit is in an on state, the control device 100 turns off the thirdB switch SW3b in step S107, and then turns off the thirdA switch SW3a, thereby turning off the third switch unit. Therefore, as shown in the middle part of FIG. 13, if the detection value of the third current sensor A13 is not zero when the thirdB switch SW3b is off and the thirdA switch SW3a is on, the control device 100 determines that there is a fault in the thirdB switch SW3b, and if the detection value is zero, the control device 100 determines that there is no fault in the thirdB switch SW3b. If it is determined that there is a fault in the thirdB switch SW3b, the control device 100 determines that there is a fault in the third switch unit, and if it is determined that there is no fault in the thirdB switch SW3b, the control device 100 determines that there is no fault in the third switch unit. This makes it possible to determine not only a fault in the third switch unit, but also a fault in the thirdB switch SW3b.

[0161] Next, a first modification of step S209 will be described. As shown in the lower part of FIG. 13, if the detection value of the third current sensor A13 is not zero even when the third switch unit (the third-A switch SW3a and the third-B switch SW3b) is off, the control device 100 determines that there is a fault in the third switch unit. Also, from a state in which the third switch unit is off, the control device 100 turns on the third-A switch SW3a in step S208, and then turns on the third-B switch SW3b, thereby turning on the third switch unit. Therefore, as shown in the middle part of FIG. 13, if the detection value of the third current sensor A13 is not zero when the third-A switch SW3a is on and the third-B switch SW3b is off, the control device 100 determines that there is a fault in the third-B switch SW3b and the third switch unit. 13, if the detection value of the third current sensor A13 with the thirdA switch SW3a and the thirdB switch SW3b on is equal to or greater than a predetermined threshold and it is determined that current is flowing normally, the control device 100 determines that there is no failure in the third switch unit. On the other hand, if the detection value of the third current sensor A13 is zero even though the third switch unit is on, the control device 100 determines that there is a failure in the third switch unit.

[0162] (Variation 2) A modified example (Modification 2) of the method for determining a failure of the third switch unit of the above embodiment will be described. Although not shown, the power supply system 30 is equipped with a voltage monitoring sensor V100 that detects and monitors the voltage between the terminals of the second storage battery 32. In Modification 2, this voltage monitoring sensor V100 is used to determine a failure. This will be described in detail below with reference to FIG. 14. FIG. 14 shows the on / off states of the third A switch SW3a and the third B switch SW3b under normal conditions, and the corresponding detection values ​​of the voltage monitoring sensor V100 and the third current sensor A13.

[0163] First, a second modification of step S108 will be described. As shown in the upper part of Fig. 14, if the detection value of the voltage monitoring sensor V100 is not the supply voltage (for example, 14 V) from the DC-DC converter 70 even though the third switch section (the third A switch SW3a and the third B switch SW3b) is turned on, the control device 100 determines that there is a fault in the third switch section. If the detection value is lower than the supply voltage and the difference is equal to or greater than a threshold value, for example, it is determined that the supply voltage is not from the DC-DC converter 70.

[0164] Furthermore, from a state in which the third switch unit is on, the control device 100 turns off the 3A switch SW3a in step S107, and then turns off the 3B switch SW3b, thereby turning off the third switch unit. Therefore, as shown in the middle part of FIG. 14, if the detected value of the voltage monitoring sensor V100 with the 3A switch SW3a off and the 3B switch SW3b on is not the inter-terminal voltage of the second storage battery 32 (e.g., 12 V), the control device 100 determines that the 3A switch SW3a has a fault, and if the detected value is the inter-terminal voltage of the second storage battery 32, the control device 100 determines that the 3A switch SW3a has no fault. Note that, for example, the control device 100 may determine that the 3A switch SW3a has no fault if the detected value of the voltage monitoring sensor V100 decreases by a predetermined value or more (e.g., 2 V or more) when the 3A switch SW3a is turned off. If it is determined that the third A switch SW3a has a fault, it is determined that the third switch unit has a fault, and if it is determined that the third A switch SW3a does not have a fault, it is determined that the third switch unit does not have a fault.

[0165] Next, a second modification of step S209 will be described. As shown in the lower part of Fig. 14, if the detected value of the voltage monitoring sensor V100 is not the voltage between the terminals of the second storage battery 32 even though the third switch unit is turned off, the control device 100 determines that there is a fault in the third switch unit.

[0166] Furthermore, in step S208, the control device 100 turns on the thirdB switch SW3b from the state in which the third switch unit is off, and then turns on the thirdA switch SW3a, thereby turning on the third switch unit. Therefore, as shown in the middle part of Fig. 14, if the detection value of the voltage monitoring sensor V100 with the thirdA switch SW3a off and the thirdB switch SW3b on is not the voltage between the terminals of the second storage battery 32, the control device 100 determines that there is a fault in the third switch unit.

[0167] Furthermore, if the control device 100 can determine that the detection value of the voltage monitoring sensor V100 when the third-A switch SW3a and the third-B switch SW3b are on is a value corresponding to the supply voltage from the DC-DC converter 70, it determines that there is no failure in the third switch unit. Note that, for example, if the detection value of the voltage monitoring sensor V100 increases by a predetermined value or more (for example, 2 V or more) when the third switch unit is turned on, it may be determined that there is no failure in the third switch unit. On the other hand, if the detection value of the voltage monitoring sensor V100 is the inter-terminal voltage of the second storage battery 32 even though the third switch unit is turned on, it determines that there is a failure in the third switch unit.

[0168] As described above, the voltage monitoring sensor V100 that monitors the voltage between the terminals of the second storage battery 32 can be used for failure determination, so the third current sensor A13 can be omitted.

[0169] (Variation 3) A modification (Modification 3) of the method for determining a fault in the third switch unit of the above embodiment will now be described. The power supply system 30 includes a voltage monitoring sensor V100, not shown, that detects and monitors the voltage between the terminals of the second storage battery 32. In Modification 3, this voltage monitoring sensor V100 is used to determine a fault. FIG. 15 shows the on / off states of the third-A switch SW3a and the third-B switch SW3b under normal conditions and the corresponding detected values ​​of the voltage monitoring sensor V100. Since the concept of fault determination in Modification 3 is essentially the same as Modification 1, with the only difference being the on / off timing of the third-A switch SW3a and the third-B switch SW3b, a detailed description thereof will be omitted. This makes it possible to determine a fault not only in the third switch unit but also in the third-B switch SW3b.

[0170] (Variation 4) A modification (Modification 4) of the method for determining a failure of the third switch unit in the above embodiment will be described. In Modification 4, as shown in Fig. 16, a failure of the third switch unit is determined using a detection value of a third voltage sensor V13. The third voltage sensor V13 has one end connected to the 3A electrical path 3A closer to the positive terminal of the second storage battery 32 than the 3A switch SW3a and the other end connected to the 3B electrical path 3B closer to the low-voltage ground line L2 than the 3B switch SW3b. Fig. 17 shows the on / off states of the 3A switch SW3a and the 3B switch SW3b under normal conditions and the corresponding detection values ​​of the third voltage sensor V13 in Modification 4.

[0171] First, a fourth modification in step S108 will be described. As shown in the upper part of Fig. 17, if the detection value of the voltage monitoring sensor V100 is not the supply voltage (for example, 14 V) from the DC-DC converter 70 even though the third switch unit (the third A switch SW3a and the third B switch SW3b) is turned on, the control device 100 determines that the third switch unit has a fault.

[0172] Furthermore, as shown in the middle of Figure 17, if the detection value of the third voltage sensor V13 when the third A switch SW3a is off and the third B switch SW3b is on is not the terminal voltage of the second storage battery 32 (for example, 12 V), the control device 100 determines that there is a fault in the third A switch SW3a, and if the detection value is the terminal voltage of the second storage battery 32, the control device 100 determines that there is no fault in the third A switch SW3a.

[0173] 17, when the detection value of the third voltage sensor V13 is "indeterminate" with the third-A switch SW3a and the third-B switch SW3b both off, the control device 100 determines that the third-B switch SW3b is not faulty. If the detection value is not "indeterminate," the control device 100 determines that the third-B switch SW3b is faulty. "Indeterminate" indicates that the value is not determined. While it may be zero, it is at least the voltage supplied from the DC-DC converter 70 and the voltage across the terminals of the second storage battery 32. Therefore, for example, if the detection value of the third voltage sensor V13 is neither the voltage supplied from the DC-DC converter 70 nor the voltage across the terminals of the second storage battery 32, the control device 100 determines that the third-B switch SW3b is not faulty. If the detection value is either of these values, the control device 100 determines that the third-B switch SW3b is faulty.

[0174] If it is determined that there is a fault in the third A switch SW3a or the third B switch SW3b, it is determined that there is a fault in the third switch unit, and if it is determined that there is no fault in the third A switch SW3a or the third B switch SW3b, it is determined that there is no fault in the third switch unit.

[0175] Next, a fourth modification in step S209 will be described. As shown in the lower part of Fig. 17, when the detected value of the third voltage sensor V13 is not indefinite (for example, when it is the supply voltage from the DC-DC converter 70 or the voltage between the terminals of the second storage battery 32) even though the third switch unit is turned off, the control device 100 determines that there is a fault in the third switch unit.

[0176] Furthermore, as shown in the middle part of Figure 17, if the detection value of the third voltage sensor V13 when the third A switch SW3a is off and the third B switch SW3b is on is not the voltage between the terminals of the second storage battery 32, the control device 100 determines that there is a fault in the third B switch SW3b and the third switch unit.

[0177] Furthermore, if the control device 100 determines that the detection value of the third voltage sensor V13 when the third A switch SW3a is on and the third B switch SW3b is on corresponds to the supply voltage from the DC-DC converter 70, it determines that there is no failure in the third A switch SW3a and the third switch unit. Otherwise, the control device 100 determines that there is a failure in the third A switch SW3a and the third switch unit.

[0178] As described above, the third voltage sensor V13 of the fourth modification can determine not only whether the third switch section has a failure, but also whether the third-A switch SW3a or the third-B switch SW3b has a failure.

[0179] Alternatively, one end of the third voltage sensor V13 may be connected to the 3A electrical path 3A closer to the low-voltage power supply line H2 than the 3A switch SW3a, and the other end may be connected to the 3B electrical path 3B closer to the negative terminal of the second storage battery 32 than the 3B switch SW3b. In this case, as in the fourth modification, it is also possible to determine which of the 3A switch SW3a and the 3B switch SW3b has a fault.

[0180] (Variation 5) A modification (Modification 5) of the method for determining a fault in the third switch unit of the above embodiment will be described. As shown in FIG. 16, Modification 5 utilizes the same detection value as Modification 4, the third voltage sensor V13. However, as shown in FIG. 18, the on / off sequence of the third A switch SW3a and the third B switch SW3b differs from that of Modification 4. Therefore, while Modification 5 can determine a fault in the third switch unit, unlike Modification 4, it cannot determine which of the third A switch SW3a and the third B switch SW3b is faulty. The concept of fault determination is essentially the same as Modification 1, etc., except that the third current sensor A13 is replaced with the third voltage sensor V13, and therefore a detailed description thereof will be omitted.

[0181] (Variation 6) A modification (Modification 6) of the method for determining a failure of the second switch unit in the above embodiment will be described. In the above embodiment, the detection value of the third current sensor A13 is used, but in Modification 6, any one of the detection value of the first voltage sensor V1, the detection value of the second voltage sensor V2, and the detection value of the second current sensor A12 may be used. This is because, as shown in FIG. 11 , if the second switch unit is normal, the detection value can be changed by turning the second switch unit on and off.

[0182] In the figure, "V1" is the column for the first voltage sensor V1, and "V2" is the column for the second voltage sensor V2. In the "V1" and "V2" columns, "depending on INV" indicates that the detected values ​​of the first voltage sensor V1 and the second voltage sensor V2 change depending on how the inverter 20 is operated to boost (or lower) the voltage. In the "A12" column for the second current sensor A12, "-A11" indicates that a negative value is detected by the first current sensor A11. In the "A12" column for the second current sensor A12, "depending on INV" indicates that the amount of current flowing varies depending on the control of the inverter 20. Therefore, the control device 100 must appropriately control the inverter 20 so that it can determine the change in the detected value by turning the second switch unit on and off. The concept of fault determination is substantially the same as in the first embodiment, which uses the detected value of the third current sensor A13, and therefore a detailed description thereof will be omitted.

[0183] (Variation 7) A modification (Modification 7) of the method for determining a failure of the second switch unit in the above embodiment will be described. In Modification 7, as shown in Fig. 19, one of the detection values ​​of the first voltage sensor V1, the second voltage sensor V2, and the second current sensor A12 is used, and the on / off sequence of the second A switch SW2a and the second B switch SW2b is changed. Note that the concept of failure determination is almost the same as in the first embodiment and Modification 6, and therefore a detailed description will be omitted.

[0184] (Variation 8) A description will be given of a modified example (Modification 8) of the method for determining a failure of the second switch unit in the above embodiment. In Modification 8, as shown in Fig. 20, a failure of the second switch unit is determined using a detection value of a fourth voltage sensor V14, which has one end connected to the second-A electrical path 2A closer to the positive terminal of the second storage battery 32 than the second-A switch SW2a and the other end connected to the second-B electrical path 2B closer to the high-voltage ground line L1 than the second-B switch SW2b.

[0185] 21 shows the on / off states of the second A switch SW2a and the second B switch SW2b and the corresponding detection values ​​of the fourth voltage sensor V14 in a normal state. Modification 8 in step S111 will now be described in detail with reference to FIG.

[0186] As shown in the upper part of Fig. 21, if the detection value of the fourth voltage sensor V14 is not "indeterminate" even though the second switch unit is turned off, it is determined that there is a fault in the second switch unit. For example, if the detection value is the terminal voltage (12 V) of the second storage battery 32 or the terminal voltage of the neutral point side smoothing capacitor C1 minus the terminal voltage of the third storage battery 33, it is determined that there is a fault in the second switch unit. Note that the terminal voltage of the neutral point side smoothing capacitor C1 is the detection value of the second voltage sensor V2, and the terminal voltage of the third storage battery 33 is 200 V.

[0187] Furthermore, in step S110, the control device 100 turns on the secondA switch SW2a from a state in which the second switch unit is off, and then turns on the secondB switch SW2b to turn on the second switch unit. Therefore, as shown in the middle part of Fig. 21, if the detection value of the fourth voltage sensor V14 in a state in which the secondA switch SW2a is on and the secondB switch SW2b is off is not "V2-200," which is the value obtained by subtracting the voltage across the third storage battery 33 from the voltage across the neutral point-side smoothing capacitor C1, the control device 100 determines that there is a fault in the secondA switch SW2a and the second switch unit.

[0188] Furthermore, if the detection value of the fourth voltage sensor V14 when the secondA switch SW2a is on and the secondB switch SW2b is on is the inter-terminal voltage (12 V) of the second storage battery 32, the control device 100 determines that there is no failure in the secondA switch SW2a, the secondB switch SW2b, and the second switch unit. On the other hand, if the detection value of the fourth voltage sensor V14 is not the inter-terminal voltage (12 V) of the second storage battery 32 even though the second switch unit is on, the control device 100 determines that there is a failure in the secondB switch SW2b and the second switch unit.

[0189] It is desirable to boost the voltage across the neutral point side smoothing capacitor C1 so that there is a clear difference between the value "V2-200" obtained by subtracting the voltage across the third storage battery 33 from the voltage across the neutral point side smoothing capacitor C1 and the voltage across the second storage battery 32 (12 V). Specifically, in step S109, it is desirable to control the inverter 20, etc., to boost the voltage across the neutral point side smoothing capacitor C1.

[0190] Furthermore, in steps S204 to S205, when the second switch unit is turned off to determine whether there is a failure in the second switch unit, it is possible to determine in the same manner whether there is a failure in the secondA switch SW2a or the secondB switch SW2b.

[0191] As described above, according to the eighth modification, it is possible to determine not only whether the second switch section has a failure, but also whether the secondA switch SW2a or the secondB switch SW2b has a failure.

[0192] (Variation 9) A modification (Modification 9) of the method for determining a failure in the second switch unit of the above embodiment will be described. Modification 9 uses the detection value of the fourth voltage sensor V14 described in Modification 8. However, as shown in FIG. 22, the order in which the second A switch SW2a and the second B switch SW2b are turned on and off differs from Modification 8.

[0193] As shown in FIG. 22, in variant 9, the detection value of the fourth voltage sensor V14 alone can be used to determine whether the third switch section is faulty. However, unlike variant 8, it is not possible to determine whether the second A switch SW2a or the second B switch SW2b is faulty.

[0194] Therefore, the detection values ​​of one or more of the first voltage sensor V1, the second voltage sensor V2, the second current sensor A12, and the third current sensor A13 are used in combination with the detection value of the fourth voltage sensor V14. That is, a fault determination for the secondB switch SW2b is made using the detection value of the fourth voltage sensor V14, and a fault determination for the secondA switch SW2a is made using the detection values ​​of one or more of the first voltage sensor V1, the second voltage sensor V2, the second current sensor A12, and the third current sensor A13. This makes it possible to determine whether the secondA switch SW2a or the secondB switch SW2b has a fault, as shown in FIG.

[0195] (Variation 10) In the power supply system 30 of the first embodiment, a switch for switching between energization and de-energization between the second storage battery 32 and the third storage battery 33 does not have to be provided between them. For example, as shown in Fig. 23, in the power supply system 30 of the first embodiment, the positive terminal of the second storage battery 32 and the negative terminal of the third storage battery 33 may be directly connected. In this case, a second A switch SW2a may be provided between the first C switch SW1c and the third storage battery 33.

[0196] (Variation 11) In the power supply system 30 of the first embodiment, the arrangement of the second storage battery 32 and the third storage battery 33 may be changed. For example, as shown in Fig. 24, in the power supply system 30 of the first embodiment, the first storage battery 31, the second storage battery 32, and the third storage battery 33 may be connected in series in this order from the high-voltage power supply line H1 side. In this case, a second A switch SW2a is provided between the negative terminal of the second storage battery 32 and the positive terminal of the third storage battery 33 to switch between energization and de-energization therebetween.

[0197] (Variation 12) In the power supply system 30 of the first embodiment, the arrangement of the first storage battery 31, the second storage battery 32, and the third storage battery 33 may be changed. For example, as shown in Fig. 25, in the power supply system 30 of the first embodiment, the batteries may be arranged in the following order from the high-voltage power supply line H1: second storage battery 32 → third storage battery 33 → first storage battery 31. Also, a series connection of a pre-charge switch Pre_G and a resistor R1 is connected in parallel to the first B switch SW1b.

[0198] In this modification 12, the firstB switch SW1b, the firstC switch SW1c, the firstD switch SW1d, and the firstE switch SW1e correspond to the first switch section. The firstC switch SW1c, the firstD switch SW1d, and the firstE switch SW1e correspond to the firstX switch. The firstB switch SW1b corresponds to the firstY switch. The secondB switch SW2b corresponds to the secondX switch, and the secondA switch SW2a corresponds to the secondY switch.

[0199] (Variation 13) In the power supply system 30 of the first embodiment, the third storage battery 33 may be omitted. For example, as shown in Fig. 26, the third storage battery 33 of the power supply system 30 of the first embodiment may be omitted.

[0200] (Variation 14) In the above embodiment, the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 14. The switching order (Modification 14) when the vehicle starts up from a stopped state will be described with reference to Figs. 27 and 28. As a premise, when the vehicle is stopped, the on / off states of the switches SW are as shown in Fig. 27(a). In other words, the third switch unit is turned on.

[0201] 27(b). That is, the control device 100 switches on the pre-charge switch Pre_P, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e. Then, the control device 100 charges the inverter-side smoothing capacitor 21 so that the voltage across the inverter-side smoothing capacitor 21 corresponds to the voltage across the terminals of the first storage battery 31.

[0202] 27(c) to 27(d). That is, the control device 100 switches on the first A switch SW1a, and then switches off the pre-charge switch Pre_P. When switching on the first switch unit, a failure determination of the first switch unit is performed in the same manner as in the first embodiment. After the failure determination, the control device 100 causes the first storage battery 31 to supply high-voltage power to the DC-DC converter 70, and causes the DC-DC converter 70 to step down the high-voltage power and supply it to the low-voltage load 72.

[0203] Then, the control device 100 switches the third switch unit OFF as shown in FIG. 28(e). At this time, a failure determination of the third switch unit is performed using the determination method described in the above embodiment and modified example. After determining a failure, the control device 100 switches the firstB switch SW1b ON as shown in FIG. 28(f). At this time, a failure determination of the firstB switch SW1b may be performed based on the detection value of the first current sensor A11, etc.

[0204] 28(g), the control device 100 switches off the first C switch SW1c, steps down the voltage applied from the first storage battery 31 using the motor 10 and the inverter 20, and charges the neutral point side smoothing capacitor C1. Specifically, the voltage across the neutral point side smoothing capacitor C1 is stepped up to a voltage equivalent to the voltage across the terminals of the first series-connected body 40 consisting of the second storage battery 32 and the third storage battery 33 (212 V).

[0205] Next, the control device 100 switches on the secondB switch SW2b as shown in FIG. 28(h). At this time, a failure determination is made for the secondB switch SW2b based on the detected values ​​of the second voltage sensor V2, the second current sensor A12, the third current sensor A13, or the fourth voltage sensor V14 of Modification 8. After determining a failure, the control device 100 boosts the supply voltage from the first series connection 40 using the motor 10 and the inverter 20, and supplies the boosted voltage to the high-voltage power supply line H1. As a result, the first storage battery 31 and the first series connection 40 are connected in parallel to the high-voltage power supply line H1.

[0206] In this modification 14, the precharge switch Pre_P, the first A switch SW1a, and the first B switch SW1b correspond to the first switch section, and the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the neutral point connection switch section.

[0207] (Variation 15) In the above embodiment, the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 15. The switching order (Modification 15) when the vehicle starts up from a stopped state will be described with reference to Figs. 29 and 30. As a premise, when the vehicle is stopped, the on / off states of the switches SW are as shown in Fig. 29(a). In other words, the third switch unit is turned on.

[0208] 29(b) when the vehicle is started while stopped. That is, the control device 100 switches on the pre-charge switch Pre_P and the first B switch SW1b. Then, the control device 100 charges the inverter-side smoothing capacitor 21 so that the voltage across the inverter-side smoothing capacitor 21 corresponds to the voltage across the first storage battery 31.

[0209] After charging is completed, the connection state changes to that shown in Fig. 29(c) to (d). That is, the control device 100 turns on the first A switch SW1a, and then turns off the pre-charge switch Pre_P. The processing in Fig. 29(a) to (d) corresponds to the third step. In this modification 15, the pre-charge switch Pre_P, the first A switch SW1a, and the first B switch SW1b correspond to the first switch section.

[0210] Furthermore, when the first switch unit is switched on, a failure determination of the first switch unit is performed in the same manner as in the first embodiment, etc. After the failure determination, the control device 100 causes the first storage battery 31 to supply high-voltage power to the DC-DC converter 70, and causes the DC-DC converter 70 to step down the high-voltage power and supply it to the low-voltage load 72.

[0211] Then, as shown in FIG. 30(e), the control device 100 switches off the third switch unit. At this time, a fault determination is performed on the third switch unit using the determination method described in the above embodiment and modified example. After the fault determination, the control device 100 turns on the first E switch SW1e and controls the motor 10 and the inverter 20 to charge the neutral point side smoothing capacitor C1, as shown in FIG. 30(f). Specifically, the voltage across the neutral point side smoothing capacitor C1 is boosted to a voltage equivalent to the voltage across the terminals of the first series connection 40 consisting of the second storage battery 32 and the third storage battery 33 (212 V).

[0212] 30(g), the control device 100 turns on the second A switch SW2a, the first D switch SW1d, and the second B switch SW2b (corresponding to the fourth step). At this time, a failure determination of the second switch unit is performed based on the detected values ​​of the second voltage sensor V2, the second current sensor A12, the third current sensor A13, or the fourth voltage sensor V14 of the eighth modification.

[0213] After determining that a fault has occurred, the control device 100 boosts the supply voltage from the first series connection 40 using the motor 10 and the inverter 20, and supplies the boosted voltage to the high-voltage power supply line H1, as shown in Fig. 30(h). As a result, the first storage battery 31 and the first series connection 40 are connected in parallel to the high-voltage power supply line H1.

[0214] In this modification 15, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the neutral point connection switch unit. Note that, because the neutral point side smoothing capacitor C1 is boosted before the first series connection body 40 is connected to the neutral point of the motor 10, inrush current can be suppressed.

[0215] (Variation 16) In the above embodiment, the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 16. The switching order (Modification 16) from when the vehicle is starting up to when the vehicle is stopped will be described with reference to Figs. 31 and 32.

[0216] As a premise of this modification 16, during vehicle startup, the connection state is as shown in FIG. 31(a). FIG. 31(a) is the same as the connection state in FIG. 30(h). When the vehicle stops from this state, the control device 100 turns off the first D switch SW1d, the second A switch SW2a, and the second B switch SW2b. At this time, a failure determination of the second switch unit may be performed in the same manner as in the above embodiment or modification.

[0217] After determining that a fault has occurred, the control device 100 controls the inverter 20 to discharge the neutral point side smoothing capacitor C1, as shown in FIG. 31(c). Then, the control device 100 switches the third switch unit ON, as shown in FIG. 31(d). At this time, the control device 100 performs a fault determination for the third switch unit in the same manner as in the above embodiment or modification. The control device 100 also switches the first E switch SW1e OFF. Next, in the state shown in FIG. 32(e), the control device 100 stops the operation of the DC-DC converter 70 and stops the power supply from the DC-DC converter 70 to the low-voltage load 72.

[0218] Thereafter, as shown in FIG. 32(f), the control device 100 switches off the first A switch SW1a and the first B switch SW1b. In this modification, the first A switch SW1a and the first B switch SW1b correspond to the first switch unit. At this time, a failure determination of the first switch unit may be performed. Then, as shown in FIG. 32(g), the control device 100 controls the inverter 20 to discharge the inverter-side smoothing capacitor 21, completes the switching, and transitions to a stopped state.

[0219] (Variation 17) In the above embodiment, the second A switch SW2a may be omitted, and the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 17. The switching order (Modification 17) when the vehicle starts up from a stopped state will be described with reference to Figs. 33 to 35. As a premise, while the vehicle is stopped, the on / off states of the switches SW are as shown in Fig. 33(a). In other words, the third switch unit is turned on.

[0220] 33(b) when the vehicle is started while stopped. That is, the control device 100 switches on the pre-charge switch Pre_P and the first B switch SW1b. Then, the control device 100 charges the inverter-side smoothing capacitor 21 so that the voltage across the inverter-side smoothing capacitor 21 corresponds to the voltage across the first storage battery 31.

[0221] After the charging is completed, the connection state shifts to the state shown in Figures 33(c) to 33(d). That is, the control device 100 switches on the first A switch SW1a, and then switches off the pre-charge switch Pre_P. When switching on the first switch unit, a failure determination of the first switch unit is performed in the same manner as in the first embodiment. After the failure determination, the control device 100 causes the first storage battery 31 to supply high-voltage power to the DC-DC converter 70, and causes the DC-DC converter 70 to step down the high-voltage power and supply it to the low-voltage load 72.

[0222] Then, the control device 100 switches the third switch unit OFF as shown in FIG. 34(e). At this time, the control device 100 performs a fault determination for the third switch unit using the determination method described in the above embodiment and modified example. After the fault determination, the control device 100 switches the first E switch SW1e ON as shown in FIG. 33(f). Thereafter, the control device 100 controls the motor 10 and the inverter 20 to step down the voltage applied from the first storage battery 31 and charge the neutral point side smoothing capacitor C1. Specifically, the control device 100 boosts the voltage across the neutral point side smoothing capacitor C1 to a voltage equivalent to the voltage across the terminals of the first series-connected body 40 consisting of the second storage battery 32 and the third storage battery 33 (212 V).

[0223] Thereafter, the control device 100 switches on the first D switch SW1d and the second B switch SW2b as shown in Fig. 34(g), At this time, a failure determination is made for the first D switch SW1d or the second B switch SW2b.

[0224] This failure determination will now be explained. At this time, if the first D switch SW1d and then the second B switch SW2b are turned on in this order, failure determination of the first D switch SW1d and the second B switch SW2b can be performed by referring to the detection values ​​of any of the voltage sensors V1 and V2 and the current sensors A11 to A13. FIG. 36 shows the relationship between the on / off states of the first D switch SW1d and the second B switch SW2b under normal conditions and their respective detection values. If the detection values ​​shown in FIG. 36(a) are not detected, a failure of the second B switch SW2b can be determined, as described above. Note that "depending on INV" indicates that the detection values ​​change depending on how the inverter 20 is controlled. Therefore, it is desirable to control the inverter 20 to adjust the voltage and current so that the detection values ​​fluctuate when the on / off state is switched.

[0225] Alternatively, the second B switch SW2b and the first D switch SW1d may be turned on in this order to determine whether a fault has occurred. Figure 37 shows the relationship between the on / off states of the first D switch SW1d and the second B switch SW2b under normal conditions and the respective detection values. If the detection values ​​shown in Figure 36(b) are not detected, a fault in the first D switch SW1d can be determined in the same manner as described above.

[0226] Furthermore, the detection value of the fourth voltage sensor V14 described in Modification 8 may be used. FIG. 37(a) shows the relationship between the on / off states of the first D switch SW1d and the second B switch SW2b under normal conditions and their detection values ​​when the first D switch SW1d and the second B switch SW2b are turned on in that order. As shown in FIG. 37(a), it is possible to determine whether the first D switch SW1d and the second B switch SW2b have a fault from the detection value of the fourth voltage sensor V14. The method of determining the fault is the same as in Modification 8, etc.

[0227] 37(b) shows the relationship between the on / off states of the first D switch SW1d and the second B switch SW2b under normal conditions and their detection values ​​when the second B switch SW2b is turned on first, followed by the first D switch SW1d. As explained in Modification 8 and other sections, FIG. 37(b) shows that a fault in the first D switch SW1d and the second B switch SW2b cannot be determined based on the detection value of the fourth voltage sensor V14 alone. Therefore, as described above, by using the detection value of the fourth voltage sensor V14 and the detection values ​​of any of the voltage sensors V1 and V2 and the current sensors A11-A13, a fault in the first D switch SW1d and the second B switch SW2b can be determined even if the switching order is changed.

[0228] 34(h), after the fault determination, the control device 100 turns off the firstB switch SW1b, and uses the motor 10 and the inverter 20 to boost the voltage applied from the first series connection 40 and charge the inverter-side smoothing capacitor 21. At this time, the voltage across the inverter-side smoothing capacitor 21 is boosted to the voltage across the terminals of the second series connection 50 (612 V).

[0229] Thereafter, the control device 100 turns on the first C switch SW1c as shown in FIG. 35(i). At this time, the control device 100 determines whether or not the detected value of any of the first voltage sensor V1 and the current sensors A11 to A13 has changed appropriately, thereby determining whether or not the first C switch SW1c has failed. Then, as shown in FIG. 35(j), the control device 100 turns off the first D switch SW1d, discharges the neutral point-side smoothing capacitor C1, and turns off the first E switch SW1e. As a result, the first to third storage batteries 31 to 33 are connected in series to the high-voltage power supply line H1.

[0230] In this modification, the first C switch SW1c and the second B switch SW2b correspond to the second switch section, and the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the neutral point connection switch section.

[0231] (Variation 18) In the above embodiment, the second A switch SW2a may be deleted, and the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 18. The switching order (Modification 18) when the vehicle starts up from a stopped state will be described with reference to Figs. 38 to 40. As a premise, when the vehicle is stopped, the on / off states of the switches SW are as shown in Fig. 38(a). In other words, the third switch unit is turned on.

[0232] 38(b). That is, the control device 100 switches on the pre-charge switch Pre_P and the first B switch SW1b. Then, the control device 100 charges the inverter-side smoothing capacitor 21 so that the voltage across the inverter-side smoothing capacitor 21 corresponds to the voltage across the first storage battery 31.

[0233] After the charging is completed, the connection state shifts to the state shown in Figures 38(c) to 38(d). That is, the control device 100 switches on the first A switch SW1a, and then switches off the pre-charge switch Pre_P. When switching on the first switch unit, a failure determination of the first switch unit is performed in the same manner as in the first embodiment. After the failure determination, the control device 100 causes the first storage battery 31 to supply high-voltage power to the DC-DC converter 70, and causes the DC-DC converter 70 to step down the high-voltage power and supply it to the low-voltage load 72.

[0234] Then, the control device 100 switches the third switch unit OFF as shown in FIG. 39(e). At this time, the control device 100 performs a fault determination for the third switch unit using the determination method described in the above embodiment and modified example. After determining a fault, the control device 100 switches the first E switch SW1e ON as shown in FIG. 39(f). Thereafter, the control device 100 controls the motor 10 and the inverter 20 to charge the neutral point side smoothing capacitor C1. Specifically, the voltage across the neutral point side smoothing capacitor C1 is boosted to a voltage equivalent to the voltage across the terminals of the first series-connected body 40 consisting of the second storage battery 32 and the third storage battery 33 (212 V).

[0235] 39(g), the control device 100 turns on the first D switch SW1d and the second B switch SW2b. At this time, similar to the seventeenth modification, a failure determination is made for the first D switch SW1d or the second B switch SW2b.

[0236] After determining that a fault has occurred, the control device 100, in the state shown in Fig. 39(h), increases the voltage applied from the first series-connected body 40 by the motor 10 and the inverter 20 to charge the inverter-side smoothing capacitor 21. At this time, the voltage across the inverter-side smoothing capacitor 21 is increased so that it becomes the voltage across the terminals of the second series-connected body 50 (612 V).

[0237] Thereafter, the control device 100 turns on the first C switch SW1c as shown in FIG. 40(i). At this time, the control device 100 determines whether or not the detected value of any of the first voltage sensor V1 and the current sensors A11 to A13 has changed appropriately, thereby determining whether or not the first C switch SW1c has failed. Then, as shown in FIG. 40(j), the control device 100 turns off the first D switch SW1d, discharges the neutral point-side smoothing capacitor C1, and turns off the first E switch SW1e. As a result, the first to third storage batteries 31 to 33 are connected in series to the high-voltage power supply line H1.

[0238] In this modification, the first C switch SW1c and the second B switch SW2b correspond to the second switch section, and the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the neutral point connection switch section.

[0239] (Variation 19) In the above embodiment, the second A switch SW2a may be omitted, and the switching order of the on / off states of the switches SW may be modified as shown in the following Modification 19. The switching order (Modification 19) when the vehicle starts up from a stopped state will be described with reference to Figs. 41 and 42. As a premise, when the vehicle is stopped, the on / off states of the switches SW are as shown in Fig. 41(a). In other words, the third switch unit is turned on.

[0240] When the vehicle is started while stopped, the connection state transitions to the connection state shown in Fig. 41(b). That is, the control device 100 switches on the pre-charge switch Pre_P and the first B switch SW1b. Then, the control device 100 charges the inverter-side smoothing capacitor 21 so that the voltage across the inverter-side smoothing capacitor 21 corresponds to the voltage across the terminals of the first storage battery 31.

[0241] After the charging is completed, the connection state shifts to the state shown in Fig. 41(c) to (d). That is, the control device 100 switches on the first A switch SW1a, and then switches off the pre-charge switch Pre_P. When switching on the first switch unit, a failure determination of the first switch unit is performed in the same manner as in the first embodiment. After the failure determination, the control device 100 causes the first storage battery 31 to supply high-voltage power to the DC-DC converter 70, and causes the DC-DC converter 70 to step down the high-voltage power and supply it to the low-voltage load 72.

[0242] Then, the control device 100 switches the third switch unit OFF as shown in FIG. 42(e). At this time, the control device 100 performs a fault determination for the third switch unit using the determination method described in the above embodiment and modified example. After the fault determination, the control device 100 switches the first E switch SW1e ON as shown in FIG. 42(f). Thereafter, the control device 100 controls the motor 10 and the inverter 20 to step down the voltage applied from the first storage battery 31 and charge the neutral point side smoothing capacitor C1. Specifically, the neutral point side smoothing capacitor C1 is charged so that the voltage across its terminals is increased to a voltage equivalent to the voltage across its terminals (212 V) of the first series-connected body 40 consisting of the second storage battery 32 and the third storage battery 33.

[0243] 42(g), the control device 100 turns on the first D switch SW1d and the second B switch SW2b. At this time, similar to the seventeenth modification, a failure determination is made for the first D switch SW1d or the second B switch SW2b.

[0244] After determining that a fault has occurred, the control device 100 uses the motor 10 and the inverter 20 to boost the voltage applied from the first series connection 40 to approximately the same as the inter-terminal voltage of the first storage battery 31, and applies the boosted voltage to the high-voltage power supply line H1. As a result, the first storage battery 31 and the first series connection 40 are connected in parallel to the high-voltage power supply line H1.

[0245] In this modification, the first C switch SW1c and the second B switch SW2b correspond to the second switch section, and the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to the neutral point connection switch section.

[0246] (Variation 20) In the above embodiment, the second A switch SW2a may be omitted, and the switching sequence of the on / off states of the switches SW may be modified as shown in the following modification 20. The switching sequence (modification 20) from when the vehicle is starting up to when the vehicle is stopped will be described with reference to Figs. 43 and 44. As a premise, during vehicle startup, the on / off states of the switches SW are as shown in Fig. 43(a). The first A switch SW1a, the second A switch SW2a, and the second B switch SW2b are turned on, and the storage batteries 31 to 33 are connected in series to the high-voltage power supply line H1.

[0247] 43(b), when the vehicle is stopped, the control device 100 switches on the first E switch SW1e, reduces the applied voltage by the inverter 20, and charges the neutral point side smoothing capacitor C1 so that the voltage across its terminals becomes 212 V. After charging, the control device 100 switches on the first D switch SW1d, boosts the applied voltage from the first storage battery 31, and applies it to the inverter side smoothing capacitor 21.

[0248] Thereafter, the control device 100 turns off the first C switch SW1c to reduce the voltage across the inverter-side smoothing capacitor 21 to 400 V, and then turns on the first B switch SW1b. At this time, it may be determined whether the first B switch SW1b, the first C switch SW1c, and the first D switch SW1d have failed.

[0249] Next, the control device 100 switches off the first D switch SW1d and the second B switch SW2b as shown in Fig. 43(c). At this time, it may be determined that the first D switch SW1d and the second B switch SW2b have failed. Then, the control device 100 operates the inverter 20 to discharge the neutral point side smoothing capacitor C1, and thereafter switches off the first E switch SW1e as shown in Fig. 43(d).

[0250] Next, the control device 100 turns on the third switch unit as shown in Fig. 44(e). At this time, it determines whether the third switch unit has failed. In Fig. 44(f), it stops the operation of the DC-DC converter 70 and stops the power supply from the DC-DC converter 70 to the low-voltage load 72.

[0251] Then, the control device 100 switches off the first A switch SW1a and the first B switch SW1b as shown in FIG. 44(g). A failure determination may be made for the first A switch SW1a and the first B switch SW1b. Thereafter, the control device 100 operates the inverter 20 to discharge the inverter-side smoothing capacitor 21. This completes the switching as shown in FIG. 44(h), and the system transitions to a stopped state.

[0252] In this modification, the first A switch SW1a and the first B switch SW1b correspond to a first switch section. The first C switch SW1c, the first D switch SW1d, and the second B switch SW2b correspond to a second switch section. The first C switch SW1c, the first D switch SW1d, and the first E switch SW1e correspond to a neutral point connection switch section.

[0253] (Variation 21) In the above embodiment, the second A switch SW2a may be omitted, and the switching sequence of the on / off states of the switches SW may be modified as shown in the following Modification 21. The switching sequence (Modification 21) from when the vehicle is starting up to when the vehicle is stopped will be described with reference to Figs. 45 and 46. As a premise, during vehicle startup, the on / off states of the switches SW are as shown in Fig. 45(a). The first A switch SW1a, the first B switch SW1b, the first D switch SW1d, the first E switch SW1e, and the second B switch SW2b are turned on, and the first storage battery 31 and the first series connection body 40 are connected in parallel to the high-voltage power supply line H1.

[0254] When the vehicle is stopped during startup, the control device 100 switches off the first D switch SW1d and the second B switch SW2b, as shown in Fig. 45(b). At this time, it may be determined that the first D switch SW1d and the second B switch SW2b are faulty. In this modification, the first C switch SW1c, the first D switch SW1d, and the second B switch SW2b correspond to the second switch section.

[0255] In the state shown in FIG. 45(c), the control device 100 causes the inverter 20 to discharge the neutral point side smoothing capacitor C1. Then, the control device 100 turns on the third switch unit as shown in FIG. 45(d). At this time, a fault determination may be made for the third switch unit. Next, in the state shown in FIG. 46(e), the control device 100 stops the operation of the DC-DC converter 70 and stops the power supply from the DC-DC converter 70 to the low-voltage load 72.

[0256] Then, the control device 100 switches off the first A switch SW1a and the first B switch SW1b, as shown in Fig. 46(f). In this modification, the first A switch SW1a and the first B switch SW1b correspond to the first switch unit. At this time, a failure determination may be made for the first A switch SW1a and the first B switch SW1b.

[0257] Thereafter, the control device 100 operates the inverter 20 to discharge the inverter-side smoothing capacitor 21. This completes the switching as shown in Fig. 46(g). Note that in this modification, the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e also correspond to the neutral point connection switch unit.

[0258] (Other variations) In the above embodiment or modification, the series connection of the precharge switch and resistor may be connected in parallel to both sides of the switch on the high-voltage power supply line side and the switch on the high-voltage ground line side. Alternatively, the series connection of the precharge switch and resistor may be connected in parallel only to the switch on the high-voltage ground line side. Alternatively, the series connection of the precharge switch and resistor may not be provided.

[0259] In the above embodiment, instead of the first C switch SW1c, the first D switch SW1d, and the first E switch SW1e, the first B switch SW1b may be a first Y switch that switches between energizing and deenergizing between the positive terminal of the first storage battery 31 and the high-voltage power supply line and H1. In this case, the second B electrical path 2B between the negative terminal of the first storage battery 31 and the high-voltage ground line L1 corresponds to the first Y electrical path.

[0260] In the above embodiment, when the first switch unit is turned off and the current between the first storage battery 31 and the high-voltage circuit 75 is cut off, the control device 100 may perform on / off control of the second switch unit to determine whether the second switch unit has failed.

[0261] The power supply system 30 of the first embodiment may have any circuit configuration as shown in FIGS.

[0262] In the above embodiment and modified examples, the common path L10 is a common portion between the third-A electrical path 3A and the second-A electrical path 2A, but it may also be a common portion between the third-B electrical path 3B and the second-B electrical path 2B. The third current sensor A13 may be provided at this location.

[0263] In the above embodiment and modified examples, each switch SW is not limited to being configured with a single switch, but may be configured with a series connection of multiple switches or a parallel connection of multiple switches.

[0264] In the above embodiment and modifications, the switches of the inverter 20 are not limited to IGBTs, but may be, for example, N-channel MOSFETs having body diodes.

[0265] In the above embodiments and modifications, the motor is not limited to being star-connected, but may be delta-connected. The motor and inverter are not limited to being three-phase, but may be two-phase, or four or more-phase. The motor is not limited to being a permanent magnet synchronous machine having a permanent magnet as a field pole on the rotor, but may be a wound field synchronous machine having a field winding as a field pole on the rotor. In this case, the rotor may be provided with both a field winding and a permanent magnet. The motor is not limited to being a synchronous machine, but may be an induction machine.

[0266] In the above embodiment and modified examples, the power storage unit is not limited to a storage battery, but may be, for example, a large-capacity electric double layer capacitor, or may include both a storage battery and an electric double layer capacitor.

[0267] In the above embodiment and modifications, the mobile body on which the power supply system is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship. Also, the power conversion device is not limited to a mobile body, but may be a stationary device.

[0268] In the above embodiment, the control device 100 changes the measurement range and resolution of the third current sensor A13 depending on whether a fault is being determined for the second switch unit or the third switch unit. As a modification of this, the control device 100 may change the measurement range and resolution of the third current sensor A13 depending on the on / off state of each switch SW. For example, when the first switch unit and the second switch unit are on and the third switch unit is off, and the high-voltage circuit 75 is connected to the power supply system 30, the measurement range of the third current sensor A13 may be widened to increase the resolution. Furthermore, when the second switch unit is off and the third switch unit is on, and the low-voltage circuit 76 is connected to the power supply system 30, the measurement range of the third current sensor A13 may be narrowed to decrease the resolution.

[0269] In the above embodiment, when performing a fault determination, the switching order of the switches SW may be changed as desired. For example, when performing a fault determination for the third switch section, the fault determination may be performed at a certain timing by turning on (or off) the 3A switch SW3a → the 3B switch SW3b in that order, and at a different timing by turning on (or off) the 3B switch SW3b → the 3A switch SW3a in that order. The same applies when determining the second switch section. This makes it possible to detect a fault regardless of whether there is a fault in the 3A switch SW3a or the 3B switch SW3b.

[0270] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0271] The following describes characteristic configurations extracted from the above-described embodiments. [Configuration 1] A power supply system (30) connected to a high-voltage circuit (75) via a high-voltage power supply line (H1) and a high-voltage ground line (L1) and connected to a low-voltage circuit (76) via a low-voltage power supply line (H2) and a low-voltage ground line (L2), the power supply system (30) including a plurality of power storage units (31-32), a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit; a switch control unit (100) that controls the first switch unit, the second switch unit, and the third switch unit; The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on the opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch that switches between energization and de-energization of a third Y electrical path that is provided between the negative electrode terminal of the second power storage unit and the low-voltage ground line, at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path; A power supply system in which a shared current sensor (A13) is provided in the common path (L10). [Configuration 2] The power supply system of configuration 1, wherein the measurement range of the shared current sensor is configured to be changeable depending on the on / off states of the first switch unit, the second switch unit, and the third switch unit, and the resolution of the shared current sensor is configured to be changed in accordance with the change in the measurement range. [Configuration 3] a failure determination unit (100) that determines whether the first switch unit, the second switch unit, and the third switch unit have a failure; The power supply system of configuration 1 or 2, wherein the failure determination unit determines whether or not there is a failure in the second switch unit based on the measurement result of the shared current sensor when the on / off state of the second switch unit is switched, and determines whether or not there is a failure in the third switch unit based on the measurement result of the shared current sensor when the on / off state of the third switch unit is switched. [Configuration 4] a measurement range of the shared current sensor is configured to be changeable in accordance with the on / off states of the first switch unit, the second switch unit, and the third switch unit, and a resolution of the shared current sensor is configured to be changed in accordance with the change in the measurement range; The power supply system according to configuration 3, wherein the failure determination unit changes the measurement range of the shared current sensor depending on whether the failure determination unit determines a failure in the second switch unit or the third switch unit. [Configuration 5] A power supply system (30) connected to a high-voltage circuit (75) via a high-voltage power supply line (H1) and a high-voltage ground line (L1) and connected to a low-voltage circuit (76) via a low-voltage power supply line (H2) and a low-voltage ground line (L2), the power supply system (30) including a plurality of power storage units (31-32), a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit, The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on the opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch that switches between energization and de-energization of a third Y electrical path provided between a negative electrode terminal of the second power storage unit and the low-voltage ground line, a switch control process for controlling the first switch unit, the second switch unit, and the third switch unit; a failure determination process for determining whether or not there is a failure in the first switch unit, the second switch unit, or the third switch unit; at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and at least a portion of the second Y electrical path; A shared current sensor (A13) is provided in the shared common path (L10), A program that, in the failure determination process, determines whether the second switch unit has a failure based on the measurement result of the shared current sensor when the on / off state of the second switch unit is switched, and also determines whether the third switch unit has a failure based on the measurement result of the shared current sensor when the on / off state of the third switch unit is switched.

[0272] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A power supply system (30) connected to a high-voltage circuit (75) via a high-voltage power supply line (H1) and a high-voltage ground line (L1) and connected to a low-voltage circuit (76) via a low-voltage power supply line (H2) and a low-voltage ground line (L2), the power supply system (30) including a plurality of power storage units (31-32), a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit; a switch control unit (100) that controls the first switch unit, the second switch unit, and the third switch unit; The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on an opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch configured to switch between energization and de-energization of a third Y electrical path provided between a negative electrode terminal of the second power storage unit and the low-voltage ground line, at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and the second Y electrical path; The power supply system has a shared current sensor (A13) provided in the common path (L10).

2. 2. The power supply system of claim 1, wherein the measurement range of the shared current sensor is configured to be changeable depending on the on / off states of the first switch unit, the second switch unit, and the third switch unit, and the resolution of the shared current sensor is configured to be changed in accordance with the change in the measurement range.

3. a failure determination unit (100) that determines whether the first switch unit, the second switch unit, and the third switch unit have a failure; 3. The power supply system according to claim 1, wherein the failure determination unit determines whether the second switch unit has failed based on a measurement result of the shared current sensor when the on / off state of the second switch unit is switched, and determines whether the third switch unit has failed based on a measurement result of the shared current sensor when the on / off state of the third switch unit is switched.

4. a measurement range of the shared current sensor is configured to be changeable in accordance with the on / off states of the first switch unit, the second switch unit, and the third switch unit, and a resolution of the shared current sensor is configured to be changed in accordance with the change in the measurement range; 4. The power supply system according to claim 3, wherein the failure determination unit changes a measurement range of the shared current sensor depending on whether the failure determination unit determines whether the second switch unit or the third switch unit has a failure.

5. A power supply system (30) connected to a high-voltage circuit (75) via a high-voltage power supply line (H1) and a high-voltage ground line (L1) and connected to a low-voltage circuit (76) via a low-voltage power supply line (H2) and a low-voltage ground line (L2), the power supply system (30) including a plurality of power storage units (31-32), a first switch unit that switches between energization and de-energization between a first power storage unit among the plurality of power storage units and the high-voltage circuit; a second switch unit that switches between energization and de-energization between the first power storage unit and the second power storage unit among the plurality of power storage units; a third switch unit that switches between energization and de-energization between the second power storage unit and the low-voltage circuit, The second switch section has a second X switch configured to switch between energization and de-energization of a second X electrical path provided between the second power storage unit and the first power storage unit; a second Y switch configured to switch between energization and de-energization of a second Y electrical path provided between one of both terminals of the second power storage unit and the high-voltage power supply line or the high-voltage ground line, the second Y switch being on an opposite side to the second X electrical path, The third switch section has a third X switch that switches between energization and de-energization of a third X electrical path that is provided between a positive electrode terminal of the second power storage unit and the low-voltage power supply line; a third Y switch that switches between energization and de-energization of a third Y electrical path provided between a negative electrode terminal of the second power storage unit and the low-voltage ground line, a switch control process for controlling the first switch unit, the second switch unit, and the third switch unit; a failure determination process for determining whether or not there is a failure in the first switch unit, the second switch unit, or the third switch unit; at least a portion of the third X electrical path is shared with at least a portion of the second X electrical path and the second Y electrical path, or at least a portion of the third Y electrical path is shared with at least a portion of the second X electrical path and the second Y electrical path; A shared current sensor (A13) is provided on the shared common path (L10), A program that, in the failure determination process, determines whether the second switch unit has a failure based on the measurement result of the shared current sensor when the on / off state of the second switch unit is switched, and determines whether the third switch unit has a failure based on the measurement result of the shared current sensor when the on / off state of the third switch unit is switched.

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