In-vehicle power supply system

Abstract

A power conversion circuit is connected to a power supply wiring part and a power ground wiring part between a battery and a power storage device. A signal ground wiring part is connected to a connection point of the power ground wiring part. At least one voltage detection circuit detects a voltage between the power supply wiring part and the signal ground wiring part. At least one potential difference detection circuit detects a potential difference between the power ground wiring part and the signal ground wiring part. A control circuit controls the power conversion circuit based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

Description

In-Vehicle Power Supply System

[0001] The present disclosure relates to an on-board power supply system, and more particularly to an on-board power supply system connected to a battery and a load of an electric vehicle, and supplying power to the load when an abnormality occurs in the battery.

[0002] Patent Document 1 discloses a device in which a GND wiring pattern for a signal control circuit section and a GND wiring pattern for a power system circuit section are configured independently of each other in a wiring pattern or wiring plane within a printed wiring board, and the GND wiring patterns are connected together using a resistor and a bypass capacitor connected in parallel with the resistor.

[0003] JP 2010-40787 A

[0004] In an in-vehicle power supply system, it is sometimes desirable to improve the control accuracy of a control circuit while suppressing the propagation of noise generated in a power conversion circuit to a signal ground wiring portion.

[0005] An on-board power supply system according to one aspect of the present disclosure includes a power supply wiring section, a power ground wiring section, a power storage device, a power conversion circuit, a control circuit, a signal ground wiring section, at least one voltage detection circuit, and at least one potential difference detection circuit. The power supply wiring section is connected to the positive electrode of a battery of an electric vehicle. The power ground wiring section is connected to the negative electrode of the battery. The power storage device is connected between the power supply wiring section and the power ground wiring section. The power conversion circuit is connected to the power supply wiring section and the power ground wiring section between the battery and the power storage device. The control circuit controls the power conversion circuit. The signal ground wiring section is connected to a connection point of the power ground wiring section. The at least one voltage detection circuit detects a voltage between the power supply wiring section and the signal ground wiring section. The at least one potential difference detection circuit detects a potential difference between the power ground wiring section and the signal ground wiring section. The control circuit controls the power conversion circuit based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

[0006] An on-board power supply system according to one aspect of the present disclosure includes a multilayer substrate, a power storage device, a power conversion circuit, a control circuit, at least one voltage detection circuit, and at least one potential difference detection circuit. The multilayer substrate has a power supply wiring section connected to a positive electrode of a battery of an electric vehicle, a power ground wiring section connected to a negative electrode of the battery, and a signal ground wiring section connected to a connection point of the power ground wiring section. The power storage device is connected between the power supply wiring section and the power ground wiring section. The power conversion circuit is connected to the power supply wiring section and the power ground wiring section between the battery and the power storage device. The control circuit controls the power conversion circuit. The at least one voltage detection circuit detects a voltage between the power supply wiring section and the signal ground wiring section. The at least one potential difference detection circuit detects a potential difference between the power ground wiring section and the signal ground wiring section. The control circuit controls the power conversion circuit based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

[0007] The in-vehicle power supply system of the present disclosure has the advantage of being able to improve the control accuracy of the control circuit while suppressing the propagation of noise generated in the power conversion circuit to the signal ground wiring portion.

[0008] FIG. 1 is a circuit diagram of an on-board power supply system according to a first embodiment. FIG. 2 is an equivalent circuit diagram of the on-board power supply system. FIG. 3A is a circuit diagram of an example of a power storage device in the on-board power supply system. FIG. 3B is a circuit diagram of another example of a power storage device in the on-board power supply system. FIG. 4 is a circuit diagram of a bidirectional DC-DC converter in the on-board power supply system. FIG. 5 is a circuit diagram of a voltage detection circuit in the on-board power supply system. FIG. 6 is a circuit diagram of a potential difference detection circuit in the on-board power supply system. FIG. 7 is a circuit diagram of a bias circuit in the on-board power supply system. FIG. 8 is a schematic plan view of a multilayer substrate in the on-board power supply system. FIG. 9A is a schematic plan view of a first layer of the multilayer substrate. FIG. 9B is a schematic plan view of a second layer of the multilayer substrate. FIG. 9C is a schematic plan view of a third layer of the multilayer substrate. FIG. 9D is a schematic plan view of a fourth layer of the multilayer substrate. Fig. 10 is a schematic plan view of a multilayer substrate in an on-board power supply system according to a first modification of embodiment 1. Fig. 11A is a schematic plan view of a first layer of the multilayer substrate. Fig. 11B is a schematic plan view of a second layer of the multilayer substrate. Fig. 11C is a schematic plan view of a third layer of the multilayer substrate. Fig. 11D is a schematic plan view of a fourth layer of the multilayer substrate. Fig. 12 is a conceptual diagram of an on-board power supply system according to a second modification of embodiment 1. Fig. 13 is a circuit diagram of an on-board power supply system according to embodiment 2. Fig. 14 is an equivalent circuit diagram of the on-board power supply system.

[0009] Hereinafter, embodiments 1 and 2 will be described with reference to the drawings. The drawings referred to in the following embodiments 1 and 2 are schematic diagrams, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the size ratios and thickness ratios between the components do not necessarily reflect the actual dimensional ratios.

[0010] First Embodiment An in-vehicle power supply system 101 according to a first embodiment will be described below with reference to FIGS. 1 to 8 and 9A to 9D.

[0011] (1) On-board Power Supply System The on-board power supply system 101 is mounted, for example, on an electric vehicle (e.g., an electric vehicle, a hybrid vehicle, etc.). The on-board power supply system 101 is connected to a battery 1 of the electric vehicle and a load 16 of the electric vehicle. The battery 1 is a rechargeable battery (e.g., a lithium-ion battery) provided in the electric vehicle. The load 16 is a vehicle control system provided in the electric vehicle, and includes, for example, an electric brake system, a shift-by-wire system, etc. of the electric vehicle. The on-board power supply system 101 is a backup power supply system mounted on the electric vehicle. For example, the on-board power supply system 101 functions as an auxiliary power supply that supplies power to the load 16 when the battery 1 is abnormal. "When the battery 1 is abnormal" includes when the voltage of the battery 1 drops below the voltage required for the operation of the load 16. Furthermore, "when the battery 1 is abnormal" includes when the battery 1 is in a permanent failure state. "When the battery 1 is in a failure state" includes when the battery 1 is short-circuited.

[0012] When the battery 1 is normal, the in-vehicle power supply system 101 supplies the power required for the operation of the load 16 from the battery 1 to the load 16, and also charges the power storage device 2 from the battery 1 via the power conversion circuit 3. When an abnormality occurs in the battery 1 (for example, a short circuit occurs in the battery 1), the in-vehicle power supply system 101 supplies the power required for the operation of the load 16 from the power storage device 2 to the load 16 via the power conversion circuit 3.

[0013] The in-vehicle power supply system 101 includes a power supply wiring section W1, a power ground wiring section W2, a power storage device 2, a power conversion circuit 3, a control circuit 4, a signal ground wiring section W3, multiple (three in FIG. 1 ) voltage detection circuits 7, and a potential difference detection circuit 13. The power supply wiring section W1 is connected to a positive electrode 11 of a battery 1 of an electric vehicle. The power ground wiring section W2 is connected to a negative electrode 12 of the battery 1. The power storage device 2 is connected between the power supply wiring section W1 and the power ground wiring section W2. The power conversion circuit 3 is connected to the power supply wiring section W1 and the power ground wiring section W2 between the battery 1 and the power storage device 2. The control circuit 4 controls the power conversion circuit 3. The signal ground wiring section W3 is connected to a connection point J1 of the power ground wiring section W2. The multiple voltage detection circuits 7 detect the voltage between the power supply wiring section W1 and the signal ground wiring section W3. The potential difference detection circuit 13 detects the potential difference between the power ground wiring section W2 and the signal ground wiring section W3. The control circuit 4 controls the power conversion circuit 3 based on values ​​obtained by correcting the detected voltages of the plurality of voltage detection circuits 7 using the detected potential difference of the potential difference detection circuit 13 .

[0014] According to the above configuration, it is possible to improve the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3.

[0015] The on-board power supply system 101 further includes a first terminal T1, a second terminal T2, a third terminal T3, a capacitor C1, and a switch SW1. The first terminal T1 is connected to the positive electrode 11 of the battery 1. The second terminal T2 is connected to the negative electrode 12 of the battery 1. The third terminal T3 is connected to a load 16 of the electric vehicle. The switch SW1 has a first end and a second end. The power conversion circuit 3 is a bidirectional DC-DC converter 30 having a first input / output terminal 31, a second input / output terminal 32, and a ground terminal 33. The power supply wiring section W1 includes a first power supply wiring W11, a second power supply wiring W12, and a third power supply wiring W13. The first power supply wiring W11 connects the first terminal T1 and the first end of the switch SW1. The second power supply wiring W12 connects the second end of the switch SW1 and the first input / output terminal 31 of the bidirectional DC-DC converter 30. The third power supply wiring W13 connects the second input / output terminal 32 of the bidirectional DC-DC converter 30 and the positive electrode 21 of the power storage device 2. The power ground wiring section W2 connects the second terminal T2 and the negative electrode 22 of the power storage device 2, and is connected to the ground terminal 33 of the bidirectional DC-DC converter 30. The capacitor C1 is connected between the second power supply wiring W12 and the power ground wiring section W2. The third terminal T3 is connected to the second power supply wiring W12. The signal ground wiring section W3 is connected to the connection point J1 of the power ground wiring section W2 between the second terminal T2 and a node N21 to which the capacitor C1 is connected in the power ground wiring section W2. The at least one voltage detection circuit 7 includes a first voltage detection circuit 71, a second voltage detection circuit 72, and a third voltage detection circuit 73. The first voltage detection circuit 71 detects the voltage between the first power supply wiring W11 and the signal ground wiring section W3. The second voltage detection circuit 72 detects the voltage between the second power supply wiring W12 and the signal ground wiring portion W3, and the third voltage detection circuit 73 detects the voltage between the third power supply wiring W13 and the signal ground wiring portion W3.

[0016] According to the above configuration, it is possible to improve the control accuracy of the bidirectional DC-DC converter 30 by the control circuit 4.

[0017] The in-vehicle power supply system 101 further includes a power supply circuit 5. The control circuit 4 has a power supply input terminal 41 and a ground terminal 42. Power for driving the control circuit 4 is input to the power supply input terminal 41. The power supply circuit 5 is connected between the second power supply wiring W12 and the power supply input terminal 41 of the control circuit 4. The ground terminal 42 of the control circuit 4 is connected to the signal ground wiring portion W3.

[0018] In addition, the in-vehicle power supply system 101 further includes a current detection unit 111 (hereinafter also referred to as the first current detection unit 111) that detects the current flowing through the second power supply wiring W12, and a current detection unit 112 (hereinafter also referred to as the second current detection unit 112) that detects the current flowing through the third power supply wiring W13.

[0019] The on-board power supply system 101 also includes a fourth terminal T4. The fourth terminal T4 is connected to an ECU (Electronic Control Unit) 18 of the electric vehicle. The on-board power supply system 101 also includes a communication circuit 6 connected to the fourth terminal T4. The communication circuit 6 functions as a communication interface for communicating between the ECU 18 and the control circuit 4. The fourth terminal T4 is connected to the ECU 18 via a harness. The communication circuit 6 receives signals from the ECU 18 and transmits them to the control circuit 4, and transmits signals from the control circuit 4 to the ECU 18.

[0020] The in-vehicle power supply system 101 also includes a connector 10, which has a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4.

[0021] The in-vehicle power supply system 101 also includes a multilayer substrate 8 (see FIG. 8), which has a first power supply wiring W11, a second power supply wiring W12, a third power supply wiring W13, a power ground wiring section W2, and a signal ground wiring section W3.

[0022] The in-vehicle power supply system 101 also has a power ground conductor PG1 to which the power ground wiring portion W2 is connected, and a signal ground conductor SG1 to which the signal ground wiring portion W3 is connected. In the in-vehicle power supply system 101, the multilayer substrate 8 has the power ground conductor PG1 (see FIG. 9C ) and the signal ground conductor SG1 (see FIG. 9C ).

[0023] FIG. 2 is an equivalent circuit of the in-vehicle power supply system 101 of FIG. 1, and shows the parasitic inductance component between the node N21 and the connection point J1 in the power ground wiring portion W2 as an inductor Lp1.

[0024] (2) Components of the Vehicle-Mounted Power Supply System The components of the vehicle-mounted power supply system 101 according to the first embodiment will be described below with reference to FIGS. 1 to 8 and 9A to 9D.

[0025] (2.1) Connector As shown in Fig. 1, the connector 10 has a plurality of terminals, including a first terminal T1, a second terminal T2, a third terminal T3, and a fourth terminal T4.

[0026] The connector 10 is disposed on the multilayer substrate 8 (see FIG. 8 ). The phrase "the connector 10 is disposed on the multilayer substrate 8" includes the connector 10 being mechanically connected to the multilayer substrate 8 and the connector 10 being electrically connected to the multilayer substrate 8. In other words, the connector 10 is mounted on the multilayer substrate 8.

[0027] The first terminal T1 is connected to a positive electrode 11 of a battery 1 of the electric vehicle. The second terminal T2 is connected to a negative electrode 12 of the battery 1. The third terminal T3 is connected to a load 16 of the electric vehicle. The fourth terminal T4 is connected to an ECU 18 of the electric vehicle.

[0028] The on-board power supply system 101 can supply power to a load 16 via the connector 10 .

[0029] (2.2) Energy Storage Device As shown in FIG. 3A , for example, the energy storage device 2 includes a plurality of energy storage elements 20 (eight in FIG. 3A ). In the energy storage device 2 in the example of FIG. 3A , the plurality of energy storage elements 20 are connected in series. The plurality of energy storage elements 20 are, for example, electric double layer capacitors. Each of the plurality of energy storage elements 20 is not limited to being an electric double layer capacitor, but may be, for example, a lithium ion capacitor. Note that each of the plurality of energy storage elements may be a lithium ion battery. The connection relationship of the plurality of energy storage elements 20 in the energy storage device 2 is not limited to the example of FIG. 3A . That is, the energy storage device 2 is not limited to a configuration in which all of the plurality of energy storage elements 20 are connected in series, and may also be a configuration in which the plurality of energy storage elements 20 are connected in parallel, or may be a configuration in which the plurality of energy storage elements 20 are connected in series-parallel, as shown in FIG. 3B .

[0030] The energy storage device 2 is not limited to a configuration including a plurality of energy storage elements 20 , and may be a configuration including only one energy storage element 20 .

[0031] (2.3) Power Conversion Circuit In this embodiment, the power conversion circuit 3 is a bidirectional DC-DC converter 30 (hereinafter sometimes abbreviated as DC-DC converter 30). The bidirectional DC-DC converter 30 is a step-up / step-down converter that can step up and step down voltage in both directions.

[0032] The DC-DC converter 30 has a first input / output terminal 31, a second input / output terminal 32, and a ground terminal 33. The first input / output terminal 31 of the DC-DC converter 30 is connected to the second terminal of the switch SW1 via the second power supply wiring W12. Therefore, the first input / output terminal 31 of the DC-DC converter 30 is connected to the positive electrode 11 of the battery 1. The ground terminal 33 of the DC-DC converter 30 is connected to a node N22 of the power ground wiring section W2. Therefore, the ground terminal 33 of the DC-DC converter 30 is connected to the negative electrode 12 of the battery 1. In other words, in the DC-DC converter 30, the battery 1 is connected between the first input / output terminal 31 and the ground terminal 33. Furthermore, the ground terminal 33 of the DC-DC converter 30 is connected to the negative electrode 22 of the power storage device 2. Furthermore, the second input / output terminal 32 of the DC-DC converter 30 is connected to the positive electrode 21 of the power storage device 2 via the third power supply wiring W13. In short, in the DC-DC converter 30 , the power storage device 2 is connected between the second input / output terminal 32 and the ground terminal 33 .

[0033] The DC-DC converter 30 is connected between a capacitor C1 (hereinafter also referred to as a first capacitor C1) and the power storage device 2. As shown in FIG. 4, the DC-DC converter 30 includes, for example, a second capacitor C11, a third capacitor C12, four switching elements Q1 to Q4, and an inductor L1.

[0034] The second capacitor C11 is connected between the first input / output terminal 31 and the ground terminal 33 of the DC-DC converter 30. Therefore, the second capacitor C11 is connected in parallel with the first capacitor C1, and is connected in parallel with the battery 1. The third capacitor C12 is connected between the second input / output terminal 32 and the ground terminal 33 of the DC-DC converter 30. Therefore, the third capacitor C12 is connected in parallel with the power storage device 2.

[0035] In the DC-DC converter 30, a series circuit of two of the four switching elements Q1 to Q4, namely, Q1 and Q2, is connected in parallel to a second capacitor C11. In the DC-DC converter 30, a series circuit of the remaining two of the four switching elements Q1 to Q4, namely, Q3 and Q4, is connected in parallel to a third capacitor C12. In the DC-DC converter 30, an inductor L1 is connected between the path between the two switching elements Q1 and Q2 and the path between the two switching elements Q3 and Q4.

[0036] Each of the four switching elements Q1 to Q4 is, for example, a normally-off n-channel metal-oxide-semiconductor field-effect transistor (MOSFET). In Fig. 4, the four diodes connected in anti-parallel to the four switching elements Q1 to Q4 in a one-to-one relationship are parasitic diodes of the n-channel MOSFETs that constitute each of the four switching elements Q1 to Q4, but are not limited to this and may be external diodes.

[0037] The DC-DC converter 30 is capable of a first conversion operation in which a first input voltage is converted into a first output voltage, and a second conversion operation in which a second input voltage is converted into a second output voltage. Each of the first conversion operation and the second conversion operation can be either a step-up operation or a step-down operation. When the DC-DC converter 30 performs the first conversion operation, the operating mode of the DC-DC converter 30 is a charge mode in which the power storage device 2 is charged. When the DC-DC converter 30 performs the second conversion operation, the operating mode of the DC-DC converter 30 is a discharge mode in which the power storage device 2 is discharged. The first input voltage is, for example, 12 V. The first output voltage is, for example, 24 V.

[0038] In the first conversion operation, the DC-DC converter 30 uses the voltage between the first input / output terminal 31 and the ground terminal 33 as a first input voltage, and uses the voltage between the second input / output terminal 32 and the ground terminal 33 as a first output voltage. In other words, in the first conversion operation, the DC-DC converter 30 converts the first input voltage input between the first input / output terminal 31 and the ground terminal 33 into a first output voltage having a voltage value different from the first input voltage, and outputs it between the second input / output terminal 32 and the ground terminal 33.

[0039] Furthermore, in the second conversion operation, the DC-DC converter 30 uses the voltage between the second input / output terminal 32 and the ground terminal 33 as a second input voltage, and uses the voltage between the first input / output terminal 31 and the ground terminal 33 as a second output voltage. In other words, in the second conversion operation, the DC-DC converter 30 converts the second input voltage input between the second input / output terminal 32 and the ground terminal 33 into a second output voltage having a voltage value different from the second input voltage, and outputs it between the first input / output terminal 31 and the ground terminal 33.

[0040] The first conversion operation of the DC-DC converter 30 is a charging operation for charging the power storage device 2 by the DC-DC converter 30. The second conversion operation of the DC-DC converter 30 is a discharging operation for discharging the power storage device 2 by the DC-DC converter 30.

[0041] The four switching elements Q1 to Q4 of the DC-DC converter 30 are controlled by a control circuit 4.

[0042] The first input / output terminal 31, the second input / output terminal 32, and the ground terminal 33 of the DC-DC converter 30 respectively constitute the first input / output terminal, the second input / output terminal, and the ground terminal of the power conversion circuit 3.

[0043] (2.4) Switch As shown in FIG. 1, the switch SW1 is connected between the first power supply wiring W11 and the second power supply wiring W12.

[0044] The switch SW1 is, for example, a semiconductor switch, and has a pair of main terminals and a control terminal. In the switch SW1, one of the pair of main terminals of the semiconductor switch (a first terminal of the switch SW1) is connected to the first terminal T1 of the connector 10 via a first power supply wiring W11. In the switch SW1, the other of the pair of main terminals of the semiconductor switch (a second terminal of the switch SW1) is connected to the first input / output terminal 31 of the DC-DC converter 30 via a second power supply wiring W12. In the switch SW1, the control terminal of the semiconductor switch is connected to the control circuit 4. The switch SW1 is controlled to an on state or an off state by the control circuit 4.

[0045] The semiconductor switch constituting the switch SW1 includes, for example, a MOSFET. More specifically, the semiconductor switch constituting the switch SW1 is a normally-off MOSFET, in which the drain terminal and source terminal of the MOSFET constitute a pair of main terminals, and the gate terminal of the MOSFET constitutes a control terminal.

[0046] 1 , the first power supply wiring W11 connects the first terminal T1 and the first end of the switch SW1. The second power supply wiring W12 connects the second end of the switch SW1 and the first input / output terminal 31 of the DC-DC converter 30. The third power supply wiring W13 connects the second input / output terminal 32 of the DC-DC converter 30 and the positive electrode 21 of the power storage device 2.

[0047] (2.6) Power Ground Wiring Section As shown in FIG. 1, the power ground wiring section W2 connects the second terminal T2 and the negative electrode 22 of the power storage device 2, and is connected to the ground terminal 33 of the DC-DC converter 30.

[0048] (2.7) Capacitor As shown in FIG. 1, the capacitor C1 is connected between the second power supply wiring W12 and the power ground wiring section W2. The capacitor C1 has a first end and a second end. The first end of the capacitor C1 is connected to a node N10 of the second power supply wiring W12. The second end of the capacitor C1 is connected to a node N21 of the power ground wiring section W2. The capacitor C1 functions as a smoothing capacitor. The capacitor C1 is, for example, an electrolytic capacitor, but may be a capacitor other than an electrolytic capacitor.

[0049] (2.8) Voltage Detection Circuits As shown in FIG. 1, the on-board power supply system 101 includes a plurality of voltage detection circuits 7 (three in FIG. 1).

[0050] Each of the plurality of voltage detection circuits 7 is, for example, as shown in FIG. 5, a resistance voltage dividing circuit 70 including a plurality of (two in FIG. 5) resistors R1 and R2 connected in series.

[0051] The plurality of voltage detection circuits 7 include a first voltage detection circuit 71 , a second voltage detection circuit 72 , and a third voltage detection circuit 73 .

[0052] The first voltage detection circuit 71 is a circuit for detecting the voltage of the battery 1. The first voltage detection circuit 71 is connected between a node N11 of the first power supply wiring W11 and a node N31 of the signal ground wiring portion W3. More specifically, in the first voltage detection circuit 71, a first end of a resistor R1 is connected to the node N11 of the first power supply wiring W11, a second end of the resistor R1 is connected to a first end of a resistor R2, a second end of the resistor R2 is connected to a node N31 of the signal ground wiring portion W3, and the connection point between the resistors R1 and R2 is connected to the control circuit 4. The first voltage detection circuit 71 detects the voltage between the first power supply wiring W11 and the signal ground wiring portion W3. That is, the first voltage detection circuit 71 detects the potential V11 of the node N11 of the first power supply wiring W11 based on the potential of the signal ground wiring portion W3.

[0053] The second voltage detection circuit 72 is a circuit for detecting the voltage between the first input / output terminal 31 of the DC-DC converter 30 and the signal ground wiring portion W3. The second voltage detection circuit 72 is connected between a node N12 of the second power supply wiring W12 and a node N32 of the signal ground wiring portion W3. More specifically, in the second voltage detection circuit 72, a first end of a resistor R1 is connected to the node N12 of the second power supply wiring W12, a second end of the resistor R1 is connected to a first end of a resistor R2, a second end of the resistor R2 is connected to the node N32 of the signal ground wiring portion W3, and the connection point between the resistors R1 and R2 is connected to the control circuit 4. The second voltage detection circuit 72 detects the voltage between the second power supply wiring W12 and the signal ground wiring portion W3. In other words, the second voltage detection circuit 72 detects the potential V12 of the node N12 of the second power supply wiring W12 relative to the potential of the signal ground wiring portion W3.

[0054] The third voltage detection circuit 73 is a circuit for detecting the voltage between the second input / output terminal 32 of the DC-DC converter 30 and the signal ground wiring portion W3. The third voltage detection circuit 73 is connected between a node N13 of the third power supply wiring W13 and a node N33 of the signal ground wiring portion W3. More specifically, in the third voltage detection circuit 73, a first end of a resistor R1 is connected to the node N13 of the third power supply wiring W13, a second end of the resistor R1 is connected to a first end of a resistor R2, a second end of the resistor R2 is connected to the node N33 of the signal ground wiring portion W3, and the connection point between the resistors R1 and R2 is connected to the control circuit 4.

[0055] (2.9) First Current Detector The first current detector 111 detects the current flowing through the second power supply wiring W12. That is, the first current detector 111 detects the current flowing through the first input / output terminal 31 of the DC-DC converter 30. The current flowing through the first input / output terminal 31 of the DC-DC converter 30 is the input current or output current of the DC-DC converter 30.

[0056] The first current detection unit 111 is, for example, a current detection resistor, but is not limited to a current detection resistor and may be a current sensor.

[0057] (2.10) Second Current Detector The second current detector 112 detects the current flowing through the third power supply wiring W13. That is, the second current detector 112 detects the current flowing through the second input / output terminal 32 of the DC-DC converter 30. The current flowing through the second input / output terminal 32 of the DC-DC converter 30 is the input current or output current of the DC-DC converter 30.

[0058] The second current detection unit 112 is, for example, a current detection resistor, but is not limited to a current detection resistor and may be a current sensor.

[0059] 1, the potential difference detection circuit 13 is connected to the power ground wiring portion W2, the signal ground wiring portion W3, and the control circuit 4. The potential difference detection circuit 13 is a circuit that detects the potential difference between the power ground wiring portion W2 and the signal ground wiring portion W3.

[0060] 6, the potential difference detection circuit 13 is, for example, an amplifier circuit 130 including an operational amplifier OP1. The potential difference detection circuit 13 has the operational amplifier OP1, resistors R3, R4, R5, and R6, and a bias circuit 14.

[0061] The operational amplifier OP1 has an inverting input terminal, a non-inverting input terminal, and an output terminal. In the potential difference detection circuit 13, the output terminal of the operational amplifier OP1 is connected to the control circuit 4.

[0062] The resistor R3 has a first end and a second end. The first end of the resistor R3 is connected to the inverting input terminal of the operational amplifier OP1. The second end of the resistor R3 is connected to the power ground wiring portion W2.

[0063] The resistor R4 has a first end and a second end, the first end of which is connected to the first end of the resistor R3 and the inverting input terminal of the operational amplifier OP1, and the second end of which is connected to the output terminal of the operational amplifier OP1.

[0064] The resistor R5 has a first end and a second end. The first end of the resistor R5 is connected to the non-inverting input terminal of the operational amplifier OP1. The second end of the resistor R5 is connected to the signal ground wiring portion W3.

[0065] The resistor R6 has a first end and a second end. The first end of the resistor R6 is connected to the non-inverting input terminal of the operational amplifier OP1 and the first end of the resistor R5. The second end of the resistor R6 is connected to the bias circuit 14 via a connection terminal T11.

[0066] 7, the bias circuit 14 includes an operational amplifier 141, a resistor R7, and a resistor R8. The bias circuit 14 is a voltage follower.

[0067] The operational amplifier 141 has an inverting input terminal, a non-inverting input terminal, and an output terminal. In the bias circuit 14, the output terminal of the operational amplifier 141 is connected to the second end of the resistor R6 via a connection terminal T11. In the bias circuit 14, the inverting input terminal and the output terminal of the operational amplifier 141 are short-circuited.

[0068] Each of the resistors R7 and R8 has a first end and a second end. The first end of the resistor R7 is connected to the power supply circuit 5. The second end of the resistor R7 is connected to the non-inverting input terminal of the operational amplifier 141 and the first end of the resistor R8. The second end of the resistor R8 is connected to the signal ground wiring portion W3.

[0069] (2.12) Control Circuit The control circuit 4 controls the DC-DC converter 30 based on at least one of the voltage detected by the first voltage detection circuit 71, the voltage detected by the second voltage detection circuit 72, and the voltage detected by the third voltage detection circuit 73, and the potential difference detected by the potential difference detection circuit 13. The control circuit 4 also controls the DC-DC converter 30 based on an external command from, for example, the ECU 18. Note that the control circuit 4 may further control the DC-DC converter 30 based on the direction (current direction) and amount of at least one of the current detected by the first current detection unit 111 and the current detected by the second current detection unit 112.

[0070] When the value obtained by correcting the detected voltage of the first voltage detection circuit 71 based on the detected potential difference of the potential difference detection circuit 13 is equal to or greater than the threshold value, the control circuit 4 controls the switch SW1 to the ON state, thereby charging the power storage device 2 from the battery 1 via the DC-DC converter 30. More specifically, the control circuit 4 controls the switch SW1 to the ON state and controls the DC-DC converter 30 so that the voltage between the second input / output terminal 32 and the ground terminal 33 of the DC-DC converter 30 becomes a desired voltage (e.g., 24 V). In other words, the control circuit 4 switches the operation mode of the DC-DC converter 30 to the charging mode, thereby charging the power storage device 2. The control circuit 4 controls the DC-DC converter 30 so that the detected voltage of the third voltage detection circuit 73 becomes the desired voltage. The control circuit 4 generates and outputs control signals to each of the four switching elements Q1 to Q4 of the DC-DC converter 30 so that the detected voltage of the third voltage detection circuit 73 becomes the desired voltage (e.g., 24 V). The threshold value is set to a voltage lower than the rated voltage of the battery 1 (e.g., 12 V) and higher than the minimum operating voltage of the load 16 (e.g., 9 V) required for the load 16 to operate normally. Therefore, for example, if the battery 1 is short-circuited, the detected voltage of the first voltage detection circuit 71 will be lower than the threshold value.

[0071] When the value obtained by correcting the detected voltage of the first voltage detection circuit 71 based on the detected potential difference of the potential difference detection circuit 13 is less than the threshold value, the control circuit 4 controls the switch SW1 to the OFF state to discharge the power storage device 2 via the DC-DC converter 30. As a result, in the in-vehicle power supply system 101, power is supplied from the power storage device 2 to the load 16 and the power supply circuit 5. The control circuit 4 controls the switch SW1 to the OFF state to operate the DC-DC converter 30 in a discharge mode and controls the DC-DC converter 30 so that the voltage between the first input / output terminal 31 and the ground terminal 33 of the DC-DC converter 30 becomes a desired voltage (e.g., 12 V) required to operate the load 16. In other words, the control circuit 4 switches the operating mode of the DC-DC converter 30 to a discharge mode and operates to continue supplying power to the load 16 using the charge of the power storage device 2. The control circuit 4 controls the DC-DC converter 30 so that the detected voltage of the second voltage detection circuit 72 becomes the desired voltage (e.g., 12 V) in order to output the desired voltage (e.g., 12 V) to the load 16. The control circuit 4 generates and outputs control signals to the four switching elements Q1 to Q4 of the DC-DC converter 30 so that the detected voltage of the second voltage detection circuit 72 becomes the desired voltage (for example, 12 V).

[0072] When charging the power storage device 2, the control circuit 4 controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the third voltage detection circuit 73 with the detected potential difference of the potential difference detection circuit 13. When discharging the power storage device 2, the control circuit 4 controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the second voltage detection circuit 72 with the detected potential difference of at least one potential difference detection circuit 13.

[0073] The executing entity of the control circuit 4 includes, for example, a computer system. The computer system has one or more computers. The computer system is mainly composed of a processor and memory as hardware. The processor executes a program recorded in the memory of the computer system to realize the function of the executing entity of the control circuit 4 in the present disclosure. The program may be pre-recorded in the memory of the computer system, provided via a telecommunications line, or recorded and provided on a non-transitory recording medium such as a memory card, optical disk, or hard disk drive (magnetic disk) readable by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The multiple electronic circuits may be integrated into a single chip or distributed across multiple chips.

[0074] An external command to the control circuit 4 is given, for example, from an ECU 18 of the electric vehicle. As a communication protocol for communicating the external command from the ECU 18 to the control circuit 4, for example, MODBUS, CAN (Controller Area Network), or other serial communication protocols can be used. The control circuit 4 communicates with the ECU 18 via a communication circuit 6 that communicates with the ECU 18.

[0075] (2.13) Power Supply Circuit The power supply circuit 5 is connected between the second power supply wiring W12 and the power supply input terminal 41 of the control circuit 4. The power supply circuit 5 supplies a power supply voltage to the control circuit 4. The power supply circuit 5 is, for example, a step-down chopper circuit. In this embodiment, the power supply circuit 5 also supplies a power supply voltage to the bias circuit 14.

[0076] (2.14) Multilayer Substrate As shown in Fig. 8, the in-vehicle power supply system 101 includes a multilayer substrate 8. The multilayer substrate 8 has a first power supply wiring W11, a second power supply wiring W12, a third power supply wiring W13, a power ground wiring portion W2, and a signal ground wiring portion W3. The multilayer substrate 8 also has a power ground conductor portion PG1 (see Fig. 9C) to which the power ground wiring portion W2 is connected, and a signal ground conductor portion SG1 (see Fig. 9C) to which the signal ground wiring portion W3 is connected.

[0077] The multilayer substrate 8 has a rectangular shape when viewed from above in the thickness direction of the multilayer substrate 8, but may have a shape other than rectangular. The multilayer substrate 8 has a first main surface 801 and a second main surface opposite the first main surface 801. Note that, in Fig. 8 and Figs. 9A to 9D, of the multiple circuit components arranged on the multilayer substrate 8 in the onboard power supply system 101, only the DC-DC converter 30, the control circuit 4, and the communication circuit 6 are illustrated. Also, Fig. 8 and Figs. 9A to 9D omit the illustration of the multiple control lines connecting the control circuit 4 to the switch SW1 and each of the switching elements Q1 to Q4 of the DC-DC converter 30.

[0078] The multilayer substrate 8 is a multilayer printed wiring board in which a plurality of insulating layers and a plurality of conductive layers are stacked in the thickness direction of the multilayer substrate 8. As shown in FIGS. 9A to 9D , the plurality of insulating layers include a first insulating layer 81, a second insulating layer 82, a third insulating layer 83, and a fourth insulating layer 84. The plurality of conductive layers include a first conductive layer, a second conductive layer, a third conductive layer, and a fourth conductive layer. The first conductive layer, the second conductive layer, the third conductive layer, and the fourth conductive layer correspond one-to-one to the first insulating layer 81, the second insulating layer 82, the third insulating layer 83, and the fourth insulating layer 84, and are stacked on the corresponding insulating layers. The material of each conductive layer is, for example, copper.

[0079] In the multilayer substrate 8, in the thickness direction of the multilayer substrate 8, from the first main surface 801 side of the multilayer substrate 8, the first insulating layer 81, the second insulating layer 82, the third insulating layer 83, and the fourth insulating layer 84 are arranged in the order of the first insulating layer 81, the second insulating layer 82, the third insulating layer 83, and the fourth insulating layer 84.

[0080] In this embodiment, the first conductor layer laminated on the first insulating layer 81 includes a first power supply wiring W11, a second power supply wiring W12, and a power ground wiring portion W2. The first conductor layer also includes a communication line portion W5 connected to the communication circuit 6. In a plan view from the thickness direction of the multilayer substrate 8, the communication line portion W5 is parallel to the power ground wiring portion W2 and is shorter than the power ground wiring portion W2.

[0081] In this embodiment, the third conductor layer laminated on the third insulating layer 83 includes a power ground conductor portion PG1 and a signal ground conductor portion SG1. In this embodiment, the signal ground conductor portion SG1 has a rectangular shape in a plan view from the thickness direction of the multilayer substrate 8, and the power ground conductor portion PG1 surrounds the signal ground conductor portion SG1. The power ground conductor portion PG1 is separated from the signal ground conductor portion SG1.

[0082] The multilayer substrate 8 also has a first via conductor portion 181 , a second via conductor portion 182 , a third via conductor portion 183 , and a fourth via conductor portion 184 .

[0083] The first via conductor 181 penetrates the first insulating layer 81 and is connected to the connection point J1 of the power ground wiring portion W2. The second via conductor 182 penetrates the second insulating layer 82 and is connected to the first via conductor 181 and the signal ground conductor SG1. The third via conductor 183 penetrates the third insulating layer 83 and is connected to the signal ground conductor SG1. The fourth via conductor 184 penetrates the fourth insulating layer 84 and is connected to the signal ground conductor SG1. In this embodiment, the signal ground wiring portion W3 includes the first via conductor 181, the second via conductor 182, the third via conductor 183, and the fourth via conductor 184.

[0084] (3) Equivalent Circuit of In-Vehicle Power Supply System In the in-vehicle power supply system 101, in order to suppress propagation of noise generated in the DC-DC converter 30 from the power ground wiring portion W2 to the signal ground wiring portion W3 while maintaining the same potential between the power ground wiring portion W2 and the signal ground wiring portion W3, the connection point J1 is located at a single point away from the DC-DC converter 30. Therefore, because the DC-DC converter 30 and the power storage device 2 are disposed at positions away from the connection point J1, an inductance component occurs between the power ground wiring portion W2 and the connection point J1. In the equivalent circuit shown in FIG. 2, this inductance component is represented by inductor Lp1.

[0085] In an in-vehicle power supply system, communication with an ECU often causes noise and affects EMI (Electro Magnetic Interference). Generally, noise tends to increase as the distance between the communication path and the ground that forms the current loop increases. Therefore, in the in-vehicle power supply system 101 of this embodiment, it is preferable that the node N30 to which the communication circuit 6 is connected in the signal ground wiring portion W3 be located near the connector 10.

[0086] Furthermore, since the in-vehicle power supply system 101 is a backup power supply that supplies power to the load 16 via the connector 10, it is preferable to reduce the impedance of the power ground wiring portion W2 connected to the connector 10.

[0087] (4) Operation of the In-Vehicle Power Supply System In the in-vehicle power supply system 101, when a current flows through the power ground wiring portion W2, a voltage drop occurs across the inductor Lp1, causing a potential difference between the power ground wiring portion W2 and the signal ground wiring portion W3. As a result, the potential difference between the power ground wiring portion W2 and the signal ground wiring portion W3 increases the errors in the detected voltages of the first voltage detection circuit 71, the second voltage detection circuit 72, and the third voltage detection circuit 73.

[0088] For example, if a short circuit occurs in battery 1, a rush current is generated by the charge stored in capacitor C1, and the rush current passes through battery 1, passes through a part of power ground wiring section W2, and returns to capacitor C1. As a result, the potential of power ground wiring section W2 drops below the potential of signal ground wiring section W3, and the errors in the detected voltages of first voltage detection circuit 71, second voltage detection circuit 72, and third voltage detection circuit 73 increase.

[0089] In contrast, in this embodiment, the control circuit 4 corrects the detected voltages of the first voltage detection circuit 71, the second voltage detection circuit 72, and the third voltage detection circuit 73 using the detected potential difference of the potential difference detection circuit 13, and controls the DC-DC converter 30.

[0090] In this embodiment, assuming that the potential of the power ground wiring portion W2 is Vpg, the potential of the signal ground wiring portion W3 is Vsg, and the potential difference between the power ground wiring portion W2 and the signal ground wiring portion W3 is Ve, Ve is expressed by the following equation (1): Ve=Vpg-Vsg Equation (1) Transforming equation (1) yields the following equation (2): Vsg=Vpg-Ve Equation (2) The control circuit 4 corrects the detected voltage (V11-Vsg) of the first voltage detection circuit 71 using the detected potential difference Ve of the potential difference detection circuit 13. When equation (3) below is not satisfied, the control circuit 4 controls the switch SW1 to the ON state and causes the DC-DC converter 30 to operate in the charge mode, and when equation (3) below is satisfied, the control circuit 4 controls the switch SW1 to the OFF state and causes the DC-DC converter 30 to operate in the discharge mode. V11-Vsg-Ve<Vth (3) In equation (3), "V11" is the potential of node N11 on first power supply wiring W11, and "Vth" is the threshold value. Also, in equation (3), "V11-Vsg" is the voltage detected by first voltage detection circuit 71, and "Ve" is the potential difference detected by potential difference detection circuit 13.

[0091] Substituting equation (2) into equation (3) yields the following equation (4): V11 - Vpg < Vth Equation (4) Therefore, the control circuit 4 controls the switch SW1 to the off state when the value (V11 - Vpg) obtained by correcting the detected voltage (V11 - Vsg) of the first voltage detection circuit 71 using the detected potential difference Ve of the potential difference detection circuit 13 is less than the threshold value Vth. In contrast, as described above, the control circuit 4 controls the switch SW1 to the on state when the value (V11 - Vpg) obtained by correcting the detected voltage (V11 - Vsg) of the first voltage detection circuit 71 using the detected potential difference Ve of the potential difference detection circuit 13 is equal to or greater than the threshold value Vth.

[0092] (4.1) Operation of DC-DC Converter in Charging Mode The control circuit 4 controls the DC-DC converter 30 based on the following equation (5): V13 - Vsg - Ve = Vo2 Equation (5) In equation (5), "V13" is the potential of node N13 on the third power supply wiring W13, and "Vo2" is the desired voltage (e.g., 24 V) to be output from the DC-DC converter 30 when charging the power storage device 2 from the battery 1. Also in equation (5), "V13 - Vsg" is the voltage detected by the third voltage detection circuit 73, and "Ve" is the potential difference detected by the potential difference detection circuit 13.

[0093] Substituting equation (2) into equation (5) yields the following equation (6): V13-Vpg=Vo2 equation (6) Therefore, in vehicle power supply system 101, it is possible to cause DC-DC converter 30 to output the desired voltage Vo2.

[0094] (4.2) Operation of Bidirectional DC-DC Converter in Discharge Mode The control circuit 4 controls the DC-DC converter 30 based on the following equation (7): V12 - Vsg - Ve = Vo1 Equation (7) In equation (7), "V12" is the potential of node N12 on second power supply wiring W12, and "Vo1" is the desired voltage to be output from the DC-DC converter 30 when power is supplied from the power storage device 2 to the load 16. Also, in equation (7), "V12 - Vsg" is the voltage detected by the second voltage detection circuit 72, and "Ve" is the potential difference detected by the potential difference detection circuit 13.

[0095] Substituting equation (2) into equation (7) yields the following equation (8): V12-Vpg=Vo1 equation (8) Therefore, in vehicle power supply system 101, it is possible to cause DC-DC converter 30 to output the desired voltage Vo1.

[0096] (5) Advantages In the in-vehicle power supply system 101 according to the first embodiment, the power conversion circuit 3 is connected to the power supply wiring section W1 and the power ground wiring section W2 between the battery 1 and the power storage device 2. The signal ground wiring section W3 is connected to the connection point J1 of the power ground wiring section W2. At least one voltage detection circuit 7 detects the voltage between the power supply wiring section W1 and the signal ground wiring section W3. The potential difference detection circuit 13 detects the potential difference between the power ground wiring section W2 and the signal ground wiring section W3. The control circuit 4 controls the power conversion circuit 3 based on values ​​obtained by correcting the detected voltages of the plurality of voltage detection circuits 7 using the detected potential difference of the potential difference detection circuit 13.

[0097] The above configuration makes it possible to suppress propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3 while improving the control accuracy of the control circuit 4. More specifically, the above configuration makes it possible to suppress propagation of noise (switching noise) generated in the power conversion circuit 3 to the signal ground wiring portion W3 while maintaining the same potential as the power ground wiring portion W2 near the connection point J1, since the signal ground wiring portion W3 is connected to the connection point J1 of the power ground wiring portion W2. Furthermore, the above configuration makes it possible for the control circuit 4 to control the power conversion circuit 3 based on values ​​obtained by correcting the detected voltages of the plurality of voltage detection circuits 7 using the detected potential difference of the potential difference detection circuit 13, thereby improving the control accuracy of the control circuit 4.

[0098] Furthermore, in comparison with a configuration in which the power ground wiring section and the signal ground wiring section are completely separated, the in-vehicle power supply system 101 does not require an isolator. That is, the in-vehicle power supply system 101 does not need to employ a circuit configuration that includes multiple voltage detection circuits that detect the voltage between each of multiple nodes in the power supply wiring section and the power ground wiring section, and multiple isolators that are provided between each of the multiple voltage detection circuits and the control circuit.

[0099] Furthermore, in the in-vehicle power supply system 101 according to the first embodiment, when the power storage device 2 is to be charged, the control circuit 4 controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the third voltage detection circuit 73 using the detected potential difference of the potential difference detection circuit 13. When the power storage device 2 is to be discharged, the control circuit 4 controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the second voltage detection circuit 72 using the detected potential difference of the potential difference detection circuit 13.

[0100] According to the above configuration, it is possible to improve the control accuracy with which the control circuit 4 controls the output voltage of the bidirectional DC-DC converter 30 to a desired voltage.

[0101] The onboard power supply system 101 according to the first embodiment includes a multilayer substrate 8, a power storage device 2, a power conversion circuit 3, a control circuit 4, multiple voltage detection circuits 7, and a potential difference detection circuit 13. The multilayer substrate 8 has a power supply wiring section W1 connected to a positive electrode 11 of a battery 1 of an electric vehicle, a power ground wiring section W2 connected to a negative electrode 12 of the battery 1, and a signal ground wiring section W3 connected to a connection point J1 of the power ground wiring section W2. The power storage device 2 is connected between the power supply wiring section W1 and the power ground wiring section W2. The power conversion circuit 3 is connected to the power supply wiring section W1 and the power ground wiring section W2 between the battery 1 and the power storage device 2. The control circuit 4 controls the power conversion circuit 3. The multiple voltage detection circuits 7 detect the voltage between the power supply wiring section W1 and the signal ground wiring section W3. The potential difference detection circuit 13 detects the potential difference between the power ground wiring section W2 and the signal ground wiring section W3. The control circuit 4 controls the power conversion circuit 3 based on values ​​obtained by correcting the detected voltages of the plurality of voltage detection circuits 7 using the detected potential difference of the potential difference detection circuit 13 .

[0102] According to the above configuration, it is possible to improve the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3.

[0103] The onboard power supply system 101 according to the first embodiment further includes a connector 10, a capacitor C1, and a switch SW1. The connector 10 is disposed on a multilayer substrate 8. The connector 10 has a first terminal T1 connected to a positive electrode 11 of the battery 1, a second terminal T2 connected to a negative electrode 12 of the battery 1, and a third terminal T3 connected to a load 16 of the electric vehicle. The switch SW1 has a first end and a second end. The power conversion circuit 3 is a bidirectional DC-DC converter 30 having a first input / output terminal 31, a second input / output terminal 32, and a ground terminal 33. The power supply wiring section W1 includes a first power supply wiring W11, a second power supply wiring W12, and a third power supply wiring W13. The first power supply wiring W11 connects the first terminal T1 and a first end of the switch SW1. The second power supply wiring W12 connects a second end of the switch SW1 and a first input / output terminal 31 of the bidirectional DC-DC converter 30. The third power supply wiring W13 connects the second input / output terminal 32 of the bidirectional DC-DC converter 30 and the positive electrode 21 of the power storage device 2. The power ground wiring section W2 connects the second terminal T2 and the negative electrode 22 of the power storage device 2, and is connected to the ground terminal 33 of the bidirectional DC-DC converter 30. The capacitor C1 is connected between the second power supply wiring W12 and the power ground wiring section W2. The third terminal T3 is connected to the second power supply wiring W12. The signal ground wiring section W3 is connected to the connection point J1 of the power ground wiring section W2 between the second terminal T2 and a node N20 to which the capacitor C1 is connected in the power ground wiring section W2. The multiple voltage detection circuits 7 include a first voltage detection circuit 71, a second voltage detection circuit 72, and a third voltage detection circuit 73. The first voltage detection circuit 71 detects the voltage between the first power supply wiring W11 and the signal ground wiring section W3. The second voltage detection circuit 72 detects the voltage between the second power supply wiring W12 and the signal ground wiring portion W3. The third voltage detection circuit 73 detects the voltage between the third power supply wiring W13 and the signal ground wiring portion W3. The control circuit 4 corrects the detected voltage of the first voltage detection circuit 71 based on the detected potential difference of the potential difference detection circuit 13. The control circuit 4 corrects the detected voltage of the second voltage detection circuit 72 based on the detected potential difference of the potential difference detection circuit 13. The control circuit 4 corrects the detected voltage of the third voltage detection circuit 73 based on the detected potential difference of the potential difference detection circuit 13.

[0104] According to the above configuration, it is possible to improve the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3.

[0105] (6) Modifications of Embodiment 1 (6.1) Modification 1 An on-board power supply system 102 according to Modification 1 of Embodiment 1 will be described with reference to Fig. 10 and Figs. 11A to 11D. With regard to the on-board power supply system 102 according to Modification 1 of Embodiment 1, components that are the same as those in the on-board power supply system 101 according to Embodiment 1 (see Figs. 1, 8, and 9A to 9D) are given the same reference numerals and descriptions thereof will be omitted. The circuit diagram of the on-board power supply system 102 is the same as the circuit diagram of the on-board power supply system 101 according to Embodiment 1 (see Figs. 1 and 2), and therefore will not be shown or described here.

[0106] In the in-vehicle power supply system 102, the shapes of the first power supply wiring W11, the second power supply wiring W12, the third power supply wiring W13 (see FIG. 1), the power ground wiring portion W2, the signal ground wiring portion W3, the power ground conductor portion PG1 (see FIG. 11C), and the signal ground conductor portion SG1 (see FIG. 11C) in the multilayer substrate 8 are different from those of the multilayer substrate 8 of the in-vehicle power supply system 101.

[0107] The multilayer substrate 8 of the in-vehicle power supply system 102 differs from the multilayer substrate 8 of the first embodiment in that the power ground conductor portion PG1 does not surround the signal ground conductor portion SG1.

[0108] The in-vehicle power supply system 102 according to the first variant of the first embodiment, like the in-vehicle power supply system 101 according to the first embodiment, is capable of improving the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3.

[0109] (6.2) Modification 2 An on-board power supply system 103 according to Modification 2 of Embodiment 1 will be described with reference to Fig. 12. With regard to the on-board power supply system 103 according to Modification 2 of Embodiment 1, components that are the same as those in the on-board power supply system 101 according to Embodiment 1 (see Figs. 1, 8, and 9A to 9D) are given the same reference numerals and descriptions thereof will be omitted. The circuit configuration of the on-board power supply system 103 is the same as the circuit configuration of the on-board power supply system 101 according to Embodiment 1 (see Figs. 1 and 2), and therefore will not be illustrated or described.

[0110] The in-vehicle power supply system 103 includes a first circuit board 80A and a second circuit board 80B instead of the multilayer board 8 of the in-vehicle power supply system 101. Each of the first circuit board 80A and the second circuit board 80B is, for example, a printed wiring board. The first circuit board 80A is larger than the second circuit board 80B. The in-vehicle power supply system 103 also includes an inter-board connector 91 disposed on the first circuit board 80A and an inter-board connector 92 disposed on the second circuit board 80B.

[0111] In the in-vehicle power supply system 103, the connector 10, the DC-DC converter 30, the capacitor C1, the switch SW1, the power storage device 2, the power supply circuit 5, the current detection units 111 and 112 are arranged on a first circuit board 80A. In the in-vehicle power supply system 103, the control circuit 4, the communication circuit 6, the plurality of voltage detection circuits 7, and the potential difference detection circuit 13 are arranged on a second circuit board 80B.

[0112] The signal ground wiring portion W3 includes a first portion W31 included in the first circuit board 80A, a second portion W32 included in the second circuit board 80B, and a portion W33 extending from the inter-board connector 91 to the inter-board connector 92. One end of the first portion W31 of the signal ground wiring portion W3 is connected to the third terminal T3 (see FIG. 1 ) of the connector 10. The other end of the first portion W31 and one end of the second portion W32 of the signal ground wiring portion W3 are connected via the inter-board connector 91 arranged on the first circuit board 80A and the inter-board connector 92 arranged on the second circuit board 80B.

[0113] The communication line portion W5 includes a first portion W51 included in the first circuit board 80A, a second portion W52 included in the second circuit board 80B, and a portion W53 extending from the inter-board connector 91 to the inter-board connector 92. One end of the first portion W51 of the communication line portion W5 is connected to the fourth terminal T4 (see FIG. 1 ) of the connector 10. The other end of the first portion W51 of the communication line portion W5 and one end of the second portion W52 are connected via the inter-board connector 91 arranged on the first circuit board 80A and the inter-board connector 92 arranged on the second circuit board 80B. The other end of the second portion W52 of the communication line portion W5 is connected to the communication circuit 6.

[0114] Each of the multiple control lines W6 that connect the control circuit 4 to the switch SW1 and the switching elements Q1 to Q4 of the DC-DC converter 30 includes a first portion W61 that is provided on the first circuit board 80A, a second portion W62 that is provided on the second circuit board 80B, and a portion W63 that extends from the inter-board connector 91 to the inter-board connector 92, and the first portion W61 and the second portion W62 are connected via the inter-board connector 91 and the inter-board connector 92.

[0115] The in-vehicle power supply system 103 according to the second modification of the first embodiment, like the in-vehicle power supply system 101 according to the first embodiment, is capable of improving the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3.

[0116] (Embodiment 2) An on-board power supply system 104 according to embodiment 2 will be described with reference to Figures 13 and 14. With regard to the on-board power supply system 104 according to embodiment 2, components that are the same as those in the on-board power supply system 101 according to embodiment 1 (see Figures 1 and 2) are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0117] (1) Configuration In the in-vehicle power supply system 104 according to the second embodiment, the number of voltage detection circuits 7 and the number of potential difference detection circuits 13 are greater than the number of voltage detection circuits 7 and the number of potential difference detection circuits 13 in the in-vehicle power supply system 101 according to the first embodiment, respectively.

[0118] The in-vehicle power supply system 104 includes four voltage detection circuits 7 and four potential difference detection circuits 13. The four voltage detection circuits 7 and the four potential difference detection circuits 13 are in one-to-one correspondence.

[0119] The four voltage detection circuits 7 include a first voltage detection circuit 71 , a second voltage detection circuit 72 , a third voltage detection circuit 73 , and a fourth voltage detection circuit 74 .

[0120] The fourth voltage detection circuit 74 is connected between a node N14 of the third power supply wiring W13 and a node N34 of the signal ground wiring portion W3. The fourth voltage detection circuit 74 is a circuit for detecting the voltage of the power storage device 2.

[0121] The four potential difference detection circuits 13 include a first potential difference detection circuit 131 , a second potential difference detection circuit 132 , a third potential difference detection circuit 133 , and a fourth potential difference detection circuit 134 .

[0122] The first potential difference detection circuit 131 detects the potential difference between the connection point J1 of the power ground wiring portion W2 and a node N31 to which the first voltage detection circuit 71 is connected in the signal ground wiring portion W3.

[0123] The second potential difference detection circuit 132 detects the potential difference between a node N22 to which the ground terminal 33 of the bidirectional DC-DC converter 30 is connected in the power ground wiring section W2 and a node N32 to which the second voltage detection circuit 72 is connected in the signal ground wiring section W3.

[0124] The third potential difference detection circuit 133 detects the potential difference between a node N23 to which the ground terminal 33 of the bidirectional DC-DC converter 30 is connected in the power ground wiring section W2 and a node N33 to which the third voltage detection circuit 73 is connected in the signal ground wiring section W3.

[0125] The fourth potential difference detection circuit 134 detects the potential difference between a node N24 to which the negative electrode 22 of the storage device 2 is connected in the power ground wiring section W2 and a node N34 to which the fourth voltage detection circuit 74 is connected in the signal ground wiring section W3.

[0126] The control circuit 4 corrects the detected voltage of the first voltage detection circuit 71 using the detected potential difference of the first potential difference detection circuit 131. The control circuit 4 also corrects the detected voltage of the second voltage detection circuit 72 using the detected potential difference of the second potential difference detection circuit 132. The control circuit 4 also corrects the detected voltage of the third voltage detection circuit 73 using the detected potential difference of the third potential difference detection circuit 133. The control circuit 4 also corrects the detected voltage of the fourth voltage detection circuit 74 using the detected potential difference of the fourth potential difference detection circuit 134.

[0127] When the value obtained by correcting the detected voltage of the first voltage detection circuit 71 using the detected potential difference of the first potential difference detection circuit 131 is equal to or greater than the threshold value, the control circuit 4 controls the switch SW1 to the ON state, causing the storage device 2 to be charged from the battery 1 via the DC-DC converter 30. When the value obtained by correcting the detected voltage of the first voltage detection circuit 71 using the detected potential difference of the first potential difference detection circuit 131 is less than the threshold value, the control circuit 4 controls the switch SW1 to the OFF state, causing the storage device 2 to be discharged via the DC-DC converter 30.

[0128] Furthermore, when the control circuit 4 charges the power storage device 2, it controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the third voltage detection circuit 73 using the detected potential difference of the third potential difference detection circuit 133. Furthermore, when the control circuit 4 discharges the power storage device 2, it controls the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the second voltage detection circuit 72 using the detected potential difference of the second potential difference detection circuit 132.

[0129] Furthermore, the control circuit 4 controls the charging and discharging of the power storage device 2 via the bidirectional DC-DC converter 30 based on a value obtained by correcting the detected voltage of the fourth voltage detection circuit 74 using the detected potential difference of the fourth potential difference detection circuit 134. For example, when the power storage device 2 is being charged, if the value obtained by correcting the detected voltage of the fourth voltage detection circuit 74 using the detected potential difference of the fourth potential difference detection circuit 134 reaches the full charge voltage of the power storage device 2, the control circuit 4 stops the operation of the bidirectional DC-DC converter 30 and stops the charging of the power storage device 2.

[0130] (2) Equivalent Circuit In the equivalent circuit shown in Fig. 14, the parasitic inductance component between the connection point J1 and the node N20 in the power ground wiring section W2 is represented by inductor Lp1. Also in Fig. 14, the parasitic inductance component between the nodes N21 and N22 in the power ground wiring section W2 is represented by inductor Lp2. Also in Fig. 14, the parasitic inductance component between the nodes N22 and N24 in the power ground wiring section W2 is represented by inductor Lp3.

[0131] (3) Operation of the Vehicle Power Supply System The operation of the vehicle power supply system 104 according to the second embodiment is substantially the same as the operation of the vehicle power supply system 101 according to the first embodiment, and therefore, a description of the same operations as those in the first embodiment will be omitted.

[0132] In the following, for example, when power is supplied from the storage device 2 to the load 16, the currents flowing through the inductors Lp1, Lp2, and Lp3 will be I1, I2, and I3, respectively, the potential at the connection point J1 will be VJ1, and the potentials at the nodes N21, N22, N23, and N24 will be V21, V22, V23, and V24, respectively.

[0133] The potential difference between connection point J1 and node N21 is expressed by the following equation (9), the potential difference between connection point J1 and node N22 is expressed by the following equation (10), the potential difference between connection point J1 and node N23 is expressed by the following equation (11), and the potential difference between connection point J1 and node N24 is expressed by the following equation (12). VJ1-V21=jωLp1×I1 Equation (9) VJ1-V22=jωLp1×I1+jωLp2×I2 Equation (10) VJ1-V23=jωLp1×I1+jωLp2×I2 Equation (11) VJ1-V24=jωLp1×I1+jωLp2×I2+jωLp3×I3 Equation (12) In equations (9) to (11), j is the imaginary unit, and ω is the angular frequency.

[0134] As can be seen from equations (9) to (11), the potential varies depending on the position of the node on the power ground wiring section W2.

[0135] In this embodiment, the control circuit 4 corrects the detected voltage of the first voltage detection circuit 71 using the detected potential difference of the first potential difference detection circuit 131. Specifically, the difference obtained by subtracting the detected potential difference of the first potential difference detection circuit 131 from the detected voltage of the first voltage detection circuit 71 is used as a correction value for the detected voltage of the first voltage detection circuit 71 to obtain the voltage of the battery 1. Therefore, the control circuit 4 can improve the detection accuracy of the voltage of the battery 1.

[0136] Furthermore, in this embodiment, the control circuit 4 corrects the voltage detected by the second voltage detection circuit 72 using the potential difference detected by the second potential difference detection circuit 132. Specifically, the difference obtained by subtracting the potential difference detected by the second potential difference detection circuit 132 from the voltage detected by the second voltage detection circuit 72 is used as a correction value for the voltage detected by the second voltage detection circuit 72 to obtain the voltage on the battery 1 side of the DC-DC converter 30 (the voltage between the first input / output terminal 31 and the ground terminal 33). Therefore, the control circuit 4 can improve the detection accuracy of the voltage on the battery 1 side of the DC-DC converter 30 (the voltage between the first input / output terminal 31 and the ground terminal 33).

[0137] Furthermore, in this embodiment, the control circuit 4 corrects the detected voltage of the third voltage detection circuit 73 using the detected potential difference of the third potential difference detection circuit 133. Specifically, the difference obtained by subtracting the detected potential difference of the third potential difference detection circuit 133 from the detected voltage of the third voltage detection circuit 73 is used as a correction value for the detected voltage of the third voltage detection circuit 73 to obtain the voltage on the power storage device 2 side of the DC-DC converter 30 (the voltage between the second input / output terminal 32 and the ground terminal 33). Therefore, the control circuit 4 can improve the detection accuracy of the voltage on the power storage device 2 side of the DC-DC converter 30 (the voltage between the second input / output terminal 32 and the ground terminal 33).

[0138] Furthermore, in this embodiment, the control circuit 4 corrects the detected voltage of the fourth voltage detection circuit 74 based on the detected potential difference of the fourth potential difference detection circuit 134. Therefore, the control circuit 4 can improve the detection accuracy of the voltage of the storage device 2.

[0139] (4) Advantages In the in-vehicle power supply system 104 according to the second embodiment, the power conversion circuit 3 is connected to the power supply wiring portion W1 and the power ground wiring portion W2 between the battery 1 and the power storage device 2. The signal ground wiring portion W3 is connected to the connection point J1 of the power ground wiring portion W2. At least one voltage detection circuit 7 detects the voltage between the power supply wiring portion W1 and the signal ground wiring portion W3. The potential difference detection circuit 13 detects the potential difference between the power ground wiring portion W2 and the signal ground wiring portion W3. The control circuit 4 controls the power conversion circuit 3 based on a value obtained by correcting the detected voltage of each of the plurality of voltage detection circuits 7 based on the detected potential difference of the corresponding potential difference detection circuit 13 among the plurality of potential difference detection circuits 13 that correspond one-to-one to the plurality of voltage detection circuits 7. Specifically, the difference obtained by subtracting the detected potential difference of the corresponding potential difference detection circuit 13 among the plurality of potential difference detection circuits 13 that correspond one-to-one to the plurality of voltage detection circuits 7 from the detected voltage of each of the plurality of voltage detection circuits 7 is used as a correction value for the detected voltage, and the power conversion circuit 3 is controlled based on this correction value.

[0140] The above configuration makes it possible to improve the control accuracy of the control circuit 4 while suppressing the propagation of noise generated in the power conversion circuit 3 to the signal ground wiring portion W3. More specifically, the above configuration makes it possible to suppress the propagation of noise (switching noise) generated in the power conversion circuit 3 to the signal ground wiring portion W3 while maintaining the same potential as the power ground wiring portion W2 near the connection point J1, since the signal ground wiring portion W3 is connected to the connection point J1 of the power ground wiring portion W2. Furthermore, the above configuration makes it possible for the control circuit 4 to control the power conversion circuit 3 based on values ​​obtained by correcting the detected voltages of the plurality of voltage detection circuits 7 based on the detected potential differences of the corresponding potential difference detection circuits 13 among the plurality of potential difference detection circuits 13 that correspond one-to-one to the plurality of voltage detection circuits 7, thereby improving the control accuracy of the control circuit 4.

[0141] (Other Modifications) The above-described first and second embodiments are merely examples of various embodiments of the present disclosure. The above-described first and second embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0142] For example, the in-vehicle power supply system 101 may include at least one voltage detection circuit 7 out of the plurality of voltage detection circuits 7 .

[0143] Furthermore, the in-vehicle power supply system 104 may be configured without the fourth voltage detection circuit 74 and the fourth potential difference detection circuit 134 .

[0144] Furthermore, the circuit configuration of the voltage detection circuit 7 may be different from that of the resistive voltage divider circuit 70 .

[0145] Furthermore, the power conversion circuit 3 is not limited to the bidirectional DC-DC converter 30, and may have a circuit configuration including a first unidirectional DC-DC converter that boosts or lowers the voltage of the battery 1, and a second unidirectional DC-DC converter that boosts or lowers the voltage of the storage device 2.

[0146] Furthermore, the circuit configuration of the potential difference detection circuit 13 may be different from the amplifier circuit 130 using the operational amplifier OP1.

[0147] Furthermore, the switch SW1 is not limited to a MOSFET, but may be, for example, a bipolar transistor, an insulated gate bipolar transistor (IGBT), a GaN-based gate injection transistor (GIT), or a bidirectional switch.

[0148] Furthermore, the on-board power supply systems 101, 102, 103, and 104 may include a relay instead of the switch SW1.

[0149] The bidirectional DC-DC converter 30 may also be a bidirectional isolated DC-DC converter, such as an LCC type bidirectional isolated DC-DC converter having a transformer, a CLLC type bidirectional isolated converter having a transformer, a DAB converter, or an FSFB converter.

[0150] Furthermore, the in-vehicle power supply systems 101, 102, 103, and 104 may further include a second switch that is different from the first switch SW1 and is connected between the node N14 and the third terminal T3.

[0151] (Aspects) The present specification discloses the following aspects.

[0152] An on-board power supply system (101; 102; 103; 104) according to a first aspect includes a power supply wiring section (W1), a power ground wiring section (W2), a power storage device (2), a power conversion circuit (3), a control circuit (4), a signal ground wiring section (W3), at least one voltage detection circuit (7), and at least one potential difference detection circuit (13). The power supply wiring section (W1) is connected to a positive electrode (11) of a battery (1) of an electric vehicle. The power ground wiring section (W2) is connected to a negative electrode (12) of the battery (1). The power storage device (2) is connected between the power supply wiring section (W1) and the power ground wiring section (W2). The power conversion circuit (3) is connected to the power supply wiring section (W1) and the power ground wiring section (W2) between the battery (1) and the power storage device (2). The control circuit (4) controls the power conversion circuit (3). The signal ground wiring portion (W3) is connected to a connection point (J1) of the power ground wiring portion (W2). At least one voltage detection circuit (7) detects a voltage between the power supply wiring portion (W1) and the signal ground wiring portion (W3). At least one potential difference detection circuit (13) detects a potential difference between the power ground wiring portion (W2) and the signal ground wiring portion (W3). The control circuit (4) controls the power conversion circuit (3) based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit (7) using the detected potential difference of the at least one potential difference detection circuit (13).

[0153] According to this aspect, it is possible to improve the control accuracy of the control circuit (4) while suppressing the propagation of noise generated in the power conversion circuit (3) to the signal ground wiring portion (W3).

[0154] The on-board power supply system (101; 102; 103; 104) according to the second aspect is the same as the on-board power supply system (101; 102; 103; 104) according to the first aspect, and further includes a first terminal (T1), a second terminal (T2), a third terminal (T3), a capacitor (C1), and a switch (SW1). The first terminal (T1) is connected to a positive electrode (11) of a battery (1). The second terminal (T2) is connected to a negative electrode (12) of the battery (1). The third terminal (T3) is connected to a load (16) of the electric vehicle. The switch (SW1) has a first end and a second end. The power conversion circuit (3) is a bidirectional DC-DC converter (30) having a first input / output terminal (31), a second input / output terminal (32), and a ground terminal (33). The power supply wiring section (W1) includes a first power supply wiring (W11), a second power supply wiring (W12), and a third power supply wiring (W13). The first power supply wiring (W11) connects the first terminal (T1) and the first end of the switch (SW1). The second power supply wiring (W12) connects the second end of the switch (SW1) and the first input / output terminal (31) of the bidirectional DC-DC converter (30). The third power supply wiring (W13) connects the second input / output terminal (32) of the bidirectional DC-DC converter (30) and the positive electrode (21) of the power storage device (2). The power ground wiring section (W2) connects the second terminal (T2) and the negative electrode (22) of the power storage device (2), and is connected to the ground terminal (33) of the bidirectional DC-DC converter (30). The capacitor (C1) is connected between the second power supply wiring (W12) and the power ground wiring portion (W2). The third terminal (T3) is connected to the second power supply wiring (W12). The signal ground wiring portion (W3) is connected to a connection point (J1) of the power ground wiring portion (W2) between the second terminal (T2) and a node (N21) in the power ground wiring portion (W2) to which the capacitor (C1) is connected. The at least one voltage detection circuit (7) includes a first voltage detection circuit (71), a second voltage detection circuit (72), and a third voltage detection circuit (73). The first voltage detection circuit (71) detects the voltage between the first power supply wiring (W11) and the signal ground wiring portion (W3). The second voltage detection circuit (72) detects the voltage between the second power supply wiring (W12) and the signal ground wiring portion (W3). The third voltage detection circuit (73) detects the voltage between the third power supply wiring (W13) and the signal ground wiring portion (W3).

[0155] According to this aspect, it is possible to improve the control accuracy of the bidirectional DC-DC converter (30) by the control circuit (4).

[0156] The on-board power supply system (101; 102; 103; 104) according to the third aspect is the second aspect, further comprising a power supply circuit (5). The control circuit (4) has a power input terminal (41) and a ground terminal (42). The power supply circuit (5) is connected between the second power supply wiring (W12) and the power input terminal (41) of the control circuit (4). The ground terminal (42) of the control circuit (4) is connected to the signal ground wiring portion (W3).

[0157] In the on-board power supply system (101; 102; 103; 104) according to a fourth aspect, in the second or third aspect, the control circuit (4) controls the switch (SW1) to an on state when a value obtained by correcting the detected voltage of the first voltage detection circuit (71) using a detected potential difference of at least one potential difference detection circuit (13) is equal to or greater than a threshold value, thereby charging the power storage device (2) from the battery (1) via the bidirectional DC-DC converter (30). When a value obtained by correcting the detected voltage of the first voltage detection circuit (71) using a detected potential difference of at least one potential difference detection circuit (13) is less than a threshold value, the control circuit (4) controls the switch (SW1) to an off state, thereby discharging the power storage device (2) via the bidirectional DC-DC converter (30).

[0158] According to this aspect, even if the battery (1) is short-circuited, it is possible to continue supplying power from the storage device (2) to the load (16) of the electric vehicle via the bidirectional DC-DC converter (30).

[0159] In the on-board power supply system (101; 102; 103; 104) according to the fifth aspect, in the fourth aspect, when the power storage device (2) is being charged, the control circuit (4) controls the bidirectional DC-DC converter (30) based on a value obtained by correcting the detected voltage of the third voltage detection circuit (73) with a detected potential difference of at least one potential difference detection circuit (13). When the power storage device (2) is being discharged, the control circuit (4) controls the bidirectional DC-DC converter (30) based on a value obtained by correcting the detected voltage of the second voltage detection circuit (72) with a detected potential difference of at least one potential difference detection circuit (13).

[0160] According to this aspect, it is possible to improve the control accuracy with which the control circuit (4) controls the output voltage of the bidirectional DC-DC converter (30) to a desired voltage.

[0161] In an on-board power supply system (104) according to a sixth aspect, in any one of the second to fifth aspects, the at least one potential difference detection circuit (13) includes a first potential difference detection circuit (131), a second potential difference detection circuit (132), and a third potential difference detection circuit (133). The first potential difference detection circuit (131) detects a potential difference between a connection point (J1) of the power ground wiring section (W2) and a node (N31) to which the first voltage detection circuit (71) is connected in the signal ground wiring section (W3). The second potential difference detection circuit (132) detects a potential difference between a node (N22) to which a ground terminal (33) of the bidirectional DC-DC converter (30) is connected in the power ground wiring section (W2) and a node (N32) to which the second voltage detection circuit (72) is connected in the signal ground wiring section (W3). The third potential difference detection circuit (133) detects a potential difference between a node (N23) to which the ground terminal (33) of the bidirectional DC-DC converter (30) is connected in the power ground wiring section (W2) and a node (N33) to which the third voltage detection circuit (73) is connected in the signal ground wiring section (W3). The control circuit (4) corrects the detected voltage of the first voltage detection circuit (71) based on the detected potential difference of the first potential difference detection circuit (131). The control circuit (4) corrects the detected voltage of the second voltage detection circuit (72) based on the detected potential difference of the second potential difference detection circuit (132). The control circuit (4) corrects the detected voltage of the third voltage detection circuit (73) based on the detected potential difference of the third potential difference detection circuit (133).

[0162] According to this aspect, it is possible to improve the control accuracy of the control circuit (4).

[0163] In the on-board power supply system (104) according to a seventh aspect, in the sixth aspect, the at least one voltage detection circuit (7) further includes a fourth voltage detection circuit (74) that detects a voltage between the positive electrode (21) of the power storage device (2) and the signal ground wiring portion (W3). The at least one potential difference detection circuit (13) further includes a fourth potential difference detection circuit (134) that detects a potential difference between a node (N24) in the power ground wiring portion (W2) to which the negative electrode (22) of the power storage device (2) is connected and a node (N34) in the signal ground wiring portion (W3) to which the fourth voltage detection circuit (74) is connected. The control circuit (4) corrects the detected voltage of the fourth voltage detection circuit (74) based on the detected potential difference of the fourth potential difference detection circuit (134).

[0164] According to this aspect, it is possible to improve the accuracy of control of the voltage of the electricity storage device (2) by the control circuit (4).

[0165] In an on-board power supply system (101; 102; 103; 104) according to an eighth aspect, in any one of the first to seventh aspects, the power storage device (2) includes a plurality of power storage elements (20). In the power storage device (2), the plurality of power storage elements (20) are connected in series, in parallel, or in series-parallel.

[0166] In the on-board power supply system (101; 102; 103; 104) according to the ninth aspect, in the eighth aspect, each of the plurality of storage elements (20) includes an electric double layer capacitor or a lithium ion capacitor.

[0167] According to this aspect, the capacity of the electricity storage device (2) can be increased.

[0168] In an on-board power supply system (101; 102; 103; 104) according to a tenth aspect, in any one of the first to ninth aspects, at least one voltage detection circuit (7) is a resistive voltage divider circuit (70) including a plurality of resistors connected in series.

[0169] In an on-board power supply system (101; 102; 103; 104) according to an eleventh aspect, in any one of the first to tenth aspects, at least one potential difference detection circuit (13) is an amplifier circuit (130) including an operational amplifier (OP1).

[0170] A vehicle power supply system (101; 102; 104) according to a twelfth aspect includes a multilayer substrate (8), a power storage device (2), a power conversion circuit (3), a control circuit (4), at least one voltage detection circuit (7), and at least one potential difference detection circuit (13). The multilayer substrate (8) has a power supply wiring section (W1) connected to a positive electrode (11) of a battery (1) of an electric vehicle, a power ground wiring section (W2) connected to a negative electrode (12) of the battery (1), and a signal ground wiring section (W3) connected to a connection point (J1) of the power ground wiring section (W2). The power storage device (2) is connected between the power supply wiring section (W1) and the power ground wiring section (W2). The power conversion circuit (3) is connected to the power supply wiring section (W1) and the power ground wiring section (W2) between the battery (1) and the power storage device (2). The control circuit (4) controls the power conversion circuit (3). At least one voltage detection circuit (7) detects a voltage between a power supply wiring section (W1) and a signal ground wiring section (W3). At least one potential difference detection circuit (13) detects a potential difference between a power ground wiring section (W2) and a signal ground wiring section (W3). A control circuit (4) controls a power conversion circuit (3) based on a value obtained by correcting a detected voltage of the at least one voltage detection circuit (7) by a detected potential difference of the at least one potential difference detection circuit (13).

[0171] According to this aspect, it is possible to improve the control accuracy of the control circuit (4) while suppressing the propagation of noise generated in the power conversion circuit (3) to the signal ground wiring portion (W3).

[0172] A vehicle power supply system (101; 102; 104) according to a thirteenth aspect is the twelfth aspect, further comprising a connector (10), a capacitor (C1), and a switch (SW1). The connector (10) is disposed on a multilayer substrate (8). The connector (10) has a first terminal (T1) connected to a positive electrode (11) of the battery (1), a second terminal (T2) connected to a negative electrode (12) of the battery (1), and a third terminal (T3) connected to a load (16) of the electric vehicle. The switch (SW1) has a first end and a second end. The power conversion circuit (3) is a bidirectional DC-DC converter (30) having a first input / output terminal (31), a second input / output terminal (32), and a ground terminal (33). The power supply wiring section (W1) includes a first power supply wiring (W11), a second power supply wiring (W12), and a third power supply wiring (W13). The first power supply wiring (W11) connects the first terminal (T1) and the first end of the switch (SW1). The second power supply wiring (W12) connects the second end of the switch (SW1) and the first input / output terminal (31) of the bidirectional DC-DC converter (30). The third power supply wiring (W13) connects the second input / output terminal (32) of the bidirectional DC-DC converter (30) and the positive electrode (21) of the power storage device (2). The power ground wiring section (W2) connects the second terminal (T2) and the negative electrode (22) of the power storage device (2), and is connected to the ground terminal (33) of the bidirectional DC-DC converter (30). The capacitor (C1) is connected between the second power supply wiring (W12) and the power ground wiring portion (W2). The third terminal (T3) is connected to the second power supply wiring (W12). The signal ground wiring portion (W3) is connected to a connection point (J1) of the power ground wiring portion (W2) between the second terminal (T2) and a node (N20) in the power ground wiring portion (W2) to which the capacitor (C1) is connected. The at least one voltage detection circuit (7) includes a first voltage detection circuit (71), a second voltage detection circuit (72), and a third voltage detection circuit (73). The first voltage detection circuit (71) detects the voltage between the first power supply wiring (W11) and the signal ground wiring portion (W3). The second voltage detection circuit (72) detects the voltage between the second power supply wiring (W12) and the signal ground wiring portion (W3).The third voltage detection circuit (73) detects the voltage between the third power supply wiring (W13) and the signal ground wiring portion (W3). The control circuit (4) corrects the detected voltage of the first voltage detection circuit (71) based on the detected potential difference of at least one potential difference detection circuit (13). The control circuit (4) corrects the detected voltage of the second voltage detection circuit (72) based on the detected potential difference of at least one potential difference detection circuit (13). The control circuit (4) corrects the detected voltage of the third voltage detection circuit (73) based on the detected potential difference of at least one potential difference detection circuit (13).

[0173] According to this aspect, it is possible to improve the control accuracy of the control circuit (4).

[0174] The on-board power supply system (101; 102; 104) according to a fourteenth aspect is the twelfth aspect, further comprising a connector (10), a capacitor (C1), and a switch (SW1). The connector (10) is disposed on a multilayer substrate (8). The connector (10) has a first terminal (T1) connected to a positive electrode (11) of the battery (1), a second terminal (T2) connected to a negative electrode (12) of the battery (1), and a third terminal (T3) connected to a load (16) of the electric vehicle. The switch (SW1) has a first end and a second end. The power conversion circuit (3) is a bidirectional DC-DC converter (30) having a first input / output terminal (31), a second input / output terminal (32), and a ground terminal (33). The power supply wiring section (W1) includes a first power supply wiring (W11), a second power supply wiring (W12), and a third power supply wiring (W13). The first power supply wiring (W11) connects the first terminal (T1) and the first end of the switch (SW1). The second power supply wiring (W12) connects the second end of the switch (SW1) and the first input / output terminal (31) of the bidirectional DC-DC converter (30). The third power supply wiring (W13) connects the second input / output terminal (32) of the bidirectional DC-DC converter (30) and the positive electrode (21) of the power storage device (2). The power ground wiring section (W2) connects the second terminal (T2) and the negative electrode (22) of the power storage device (2), and is connected to the ground terminal (33) of the bidirectional DC-DC converter (30). The capacitor (C1) is connected between the second power supply wiring (W12) and the power ground wiring portion (W2). The third terminal (T3) is connected to the second power supply wiring (W12). The signal ground wiring portion (W3) is connected to a connection point (J1) of the power ground wiring portion (W2) between the second terminal (T2) and a node (N20) in the power ground wiring portion (W2) to which the capacitor (C1) is connected. The at least one voltage detection circuit (7) includes a first voltage detection circuit (71), a second voltage detection circuit (72), and a third voltage detection circuit (73). The first voltage detection circuit (71) detects the voltage between the first power supply wiring (W11) and the signal ground wiring portion (W3). The second voltage detection circuit (72) detects the voltage between the second power supply wiring (W12) and the signal ground wiring portion (W3).The third voltage detection circuit (73) detects the voltage between the third power supply wiring (W13) and the signal ground wiring section (W3). At least one potential difference detection circuit (13) includes a first potential difference detection circuit (131), a second potential difference detection circuit (132), a third potential difference detection circuit (133), and a fourth potential difference detection circuit (134). The first potential difference detection circuit (131) detects the potential difference between a connection point (J1) of the power ground wiring section (W2) and a node (N31) to which the first voltage detection circuit (71) is connected in the signal ground wiring section (W3). The second potential difference detection circuit (132) detects the potential difference between a node (N22) to which a ground terminal (33) of the bidirectional DC-DC converter (30) is connected in the power ground wiring section (W2) and a node (N32) to which the second voltage detection circuit (72) is connected in the signal ground wiring section (W3). The third potential difference detection circuit (133) detects a potential difference between a node (N23) to which the ground terminal (33) of the bidirectional DC-DC converter (30) is connected in the power ground wiring section (W2) and a node (N33) to which the third voltage detection circuit (73) is connected in the signal ground wiring section (W3). The control circuit (4) corrects the detected voltage of the first voltage detection circuit (71) based on the detected potential difference of the first potential difference detection circuit (131). The control circuit (4) corrects the detected voltage of the second voltage detection circuit (72) based on the detected potential difference of the second potential difference detection circuit (132). The control circuit (4) corrects the detected voltage of the third voltage detection circuit (73) based on the detected potential difference of the third potential difference detection circuit (133).

[0175] According to this aspect, it is possible to improve the control accuracy of the control circuit (4).

[0176] In the on-board power supply system (101; 102; 104) according to the fifteenth aspect, in the fourteenth aspect, the control circuit (4) controls the switch (SW1) to an on state when a value obtained by correcting the detected voltage of the first voltage detection circuit (71) using the detected potential difference of the first potential difference detection circuit (131) is equal to or greater than a threshold value, thereby charging the power storage device (2) from the battery (1) via the bidirectional DC-DC converter (30). When a value obtained by correcting the detected voltage of the first voltage detection circuit (71) using the detected potential difference of the first potential difference detection circuit (131) is less than the threshold value, the control circuit (4) controls the switch (SW1) to an off state, thereby discharging the power storage device (2) via the bidirectional DC-DC converter (30).

[0177] In the in-vehicle power supply system (101; 102; 103; 104) according to the sixteenth aspect, in the fourteenth aspect, when the power storage device (2) is being charged, the control circuit (4) controls the bidirectional DC-DC converter (30) based on a value obtained by correcting the detected voltage of the third voltage detection circuit (73) with a detected potential difference of at least one potential difference detection circuit (13). When the power storage device (2) is being discharged, the control circuit (4) controls the bidirectional DC-DC converter (30) based on a value obtained by correcting the detected voltage of the second voltage detection circuit (72) with a detected potential difference of at least one potential difference detection circuit (13).

[0178] According to this aspect, it is possible to improve the control accuracy with which the control circuit (4) controls the output voltage of the bidirectional DC-DC converter (30) to a desired voltage.

[0179] The on-board power supply system (101; 102; 104) according to a seventeenth aspect is any one of the thirteenth to sixteenth aspects, further including a communication circuit (6) that communicates with an ECU (18) of the electric vehicle. The connector (10) further includes a fourth terminal (T4) connected to the ECU (18). The communication circuit (6) is connected between the fourth terminal (T4) and the control circuit (4), and is connected to the signal ground wiring portion (W3).

[0180] REFERENCE SIGNS LIST 1 battery 11 positive electrode 12 negative electrode 2 power storage device 20 power storage element 21 positive electrode 22 negative electrode 3 power conversion circuit 30 bidirectional DC-DC converter 31 first input / output terminal 32 second input / output terminal 33 ground terminal 4 control circuit 41 power supply input terminal 42 ground terminal 5 power supply circuit 6 communication circuit 7 voltage detection circuit 70 resistive voltage divider circuit 71 first voltage detection circuit 72 second voltage detection circuit 73 third voltage detection circuit 74 fourth voltage detection circuit 8 multilayer substrate 81 first insulating layer 82 second insulating layer 83 third insulating layer 84 fourth insulating layer 10 connector 16 load 111 current detection unit 112 current detection unit 13 potential difference detection circuit 130 amplifier circuit 131 first potential difference detection circuit 132 second potential difference detection circuit 133 Third potential difference detection circuit 134 Fourth potential difference detection circuit 18 ECU 101, 102, 103, 104 In-vehicle power supply system C1 Capacitor N10, N11, N12, N13, N14 Nodes N20, N21, N22, N23, N24 Nodes N30, N31, N32, N33, N34 Nodes SW1 Switch T1 First terminal T2 Second terminal T3 Third terminal T4 Fourth terminal W1 Power supply wiring section W11 First power supply wiring W12 Second power supply wiring W13 Third power supply wiring W2 Power ground wiring section W3 Signal ground wiring section

Claims

1. An on-board power supply system comprising: a power supply wiring section connected to the positive electrode of a battery of an electric vehicle; a power ground wiring section connected to the negative electrode of the battery; a power storage device connected between the power supply wiring section and the power ground wiring section; a power conversion circuit connected to the power supply wiring section and the power ground wiring section between the battery and the power storage device; a control circuit for controlling the power conversion circuit; a signal ground wiring section connected to a connection point of the power ground wiring section; at least one voltage detection circuit for detecting a voltage between the power supply wiring section and the signal ground wiring section; and at least one potential difference detection circuit for detecting a potential difference between the power ground wiring section and the signal ground wiring section, wherein the control circuit controls the power conversion circuit based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

2. A power conversion circuit further comprising: a first terminal connected to the positive electrode of the battery; a second terminal connected to the negative electrode of the battery; a third terminal connected to a load of the electric vehicle; a capacitor; and a switch having a first end and a second end, wherein the power conversion circuit is a bidirectional DC-DC converter having a first input / output terminal, a second input / output terminal, and a ground terminal, and the power supply wiring unit includes: a first power supply wiring connecting the first terminal and the first end of the switch; a second power supply wiring connecting the second end of the switch and the first input / output terminal of the bidirectional DC-DC converter; and a third power supply wiring connecting the second input / output terminal of the bidirectional DC-DC converter and the positive electrode of the power storage device, and the power ground wiring unit connects the second terminal and the negative electrode of the power storage device and is connected to the ground terminal of the bidirectional DC-DC converter, the capacitor is connected between the second power supply wiring and the power ground wiring unit, and the third terminal is connected to the second power supply wiring, 2. The in-vehicle power supply system according to claim 1, wherein the signal ground wiring section is connected to the connection point of the power ground wiring section between the second terminal and a node to which the capacitor is connected in the power ground wiring section, and the at least one voltage detection circuit includes: a first voltage detection circuit that detects a voltage between the first power supply wiring and the signal ground wiring section; a second voltage detection circuit that detects a voltage between the second power supply wiring and the signal ground wiring section; and a third voltage detection circuit that detects a voltage between the third power supply wiring and the signal ground wiring section.

3. The on-board power supply system according to claim 2, further comprising a power supply circuit, wherein the control circuit has a power supply input terminal and a ground terminal, the power supply circuit being connected between the second power supply wiring and the power supply input terminal of the control circuit, and the ground terminal of the control circuit being connected to the signal ground wiring section.

4. The automotive power supply system according to claim 2 or 3, wherein the control circuit controls the switch to an on state to charge the storage device from the battery via the bidirectional DC-DC converter when a value obtained by correcting the detected voltage of the first voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit is equal to or greater than a threshold value, and controls the switch to an off state to discharge the storage device via the bidirectional DC-DC converter when a value obtained by correcting the detected voltage of the first voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit is less than the threshold value.

5. The automotive power supply system according to claim 4, wherein the control circuit, when charging the storage device, controls the bidirectional DC-DC converter based on a value obtained by correcting the detected voltage of the third voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit, and when discharging the storage device, controls the bidirectional DC-DC converter based on a value obtained by correcting the detected voltage of the second voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

6. The automotive power supply system according to any one of claims 2 to 5, wherein the at least one potential difference detection circuit includes: a first potential difference detection circuit that detects a potential difference between the connection point of the power ground wiring section and a node to which the first voltage detection circuit is connected in the signal ground wiring section; a second potential difference detection circuit that detects a potential difference between a node to which the ground end of the bidirectional DC-DC converter is connected in the power ground wiring section and a node to which the second voltage detection circuit is connected in the signal ground wiring section; and a third potential difference detection circuit that detects a potential difference between the node to which the ground end of the bidirectional DC-DC converter is connected in the power ground wiring section and a node to which the third voltage detection circuit is connected in the signal ground wiring section; and wherein the control circuit corrects the detected voltage of the first voltage detection circuit by the detected potential difference of the first potential difference detection circuit, corrects the detected voltage of the second voltage detection circuit by the detected potential difference of the second potential difference detection circuit, and corrects the detected voltage of the third voltage detection circuit by the detected potential difference of the third potential difference detection circuit.

7. The automotive power supply system according to claim 6, wherein the at least one voltage detection circuit further includes a fourth voltage detection circuit that detects a voltage between the positive electrode of the power storage device and the signal ground wiring section, the at least one potential difference detection circuit further includes a fourth potential difference detection circuit that detects a potential difference between a node in the power ground wiring section to which the negative electrode of the power storage device is connected and a node in the signal ground wiring section to which the fourth voltage detection circuit is connected, and the control circuit corrects the detected voltage of the fourth voltage detection circuit using the detected potential difference of the fourth potential difference detection circuit.

8. The in-vehicle power supply system according to any one of claims 1 to 7, wherein the power storage device includes a plurality of power storage elements, and in the power storage device, the plurality of power storage elements are connected in series, in parallel, or in a series-parallel configuration.

9. The in-vehicle power supply system according to claim 8, wherein each of the plurality of power storage elements includes an electric double layer capacitor or a lithium ion capacitor.

10. The in-vehicle power supply system according to any one of claims 1 to 9, wherein the at least one voltage detection circuit is a resistive voltage divider circuit including a plurality of resistors connected in series.

11. The in-vehicle power supply system according to any one of claims 1 to 10, wherein the at least one potential difference detection circuit is an amplifier circuit including an operational amplifier.

12. An on-board power supply system comprising: a multilayer substrate having a power supply wiring section connected to the positive electrode of a battery of an electric vehicle, a power ground wiring section connected to the negative electrode of the battery, and a signal ground wiring section connected to a connection point of the power ground wiring section; a power storage device connected between the power supply wiring section and the power ground wiring section; a power conversion circuit connected to the power supply wiring section and the power ground wiring section between the battery and the power storage device; a control circuit for controlling the power conversion circuit; at least one voltage detection circuit for detecting a voltage between the power supply wiring section and the signal ground wiring section; and at least one potential difference detection circuit for detecting a potential difference between the power ground wiring section and the signal ground wiring section, wherein the control circuit controls the power conversion circuit based on a value obtained by correcting the detected voltage of the at least one voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

13. A power conversion circuit further comprises: a connector disposed on the multilayer substrate and having a first terminal connected to the positive electrode of the battery, a second terminal connected to the negative electrode of the battery, and a third terminal connected to a load of the electric vehicle; a capacitor; and a switch having a first end and a second end, wherein the power conversion circuit is a bidirectional DC-DC converter having a first input / output terminal, a second input / output terminal, and a ground terminal, the power supply wiring unit includes: a first power supply wiring connecting the first terminal and the first end of the switch, a second power supply wiring connecting the second end of the switch and the first input / output terminal of the bidirectional DC-DC converter, and a third power supply wiring connecting the second input / output terminal of the bidirectional DC-DC converter and the positive electrode of the power storage device, the power ground wiring unit connects the second terminal and the negative electrode of the power storage device and is connected to the ground terminal of the bidirectional DC-DC converter, the capacitor is connected between the second power supply wiring and the power ground wiring unit, and the third terminal is connected to the second power supply wiring, 13. The in-vehicle power supply system according to claim 12, wherein the signal ground wiring section is connected to the connection point of the power ground wiring section between the second terminal and a node to which the capacitor is connected in the power ground wiring section, and the at least one voltage detection circuit includes: a first voltage detection circuit that detects a voltage between the first power supply wiring and the signal ground wiring section; a second voltage detection circuit that detects a voltage between the second power supply wiring and the signal ground wiring section; and a third voltage detection circuit that detects a voltage between the third power supply wiring and the signal ground wiring section, and the control circuit corrects the detected voltage of the first voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit, corrects the detected voltage of the second voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit, and corrects the detected voltage of the third voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

14. A power conversion circuit further comprises: a connector disposed on the multilayer substrate and having a first terminal connected to the positive electrode of the battery, a second terminal connected to the negative electrode of the battery, and a third terminal connected to a load of the electric vehicle; a capacitor; and a switch having a first end and a second end, wherein the power conversion circuit is a bidirectional DC-DC converter having a first input / output end, a second input / output end, and a ground end, the power supply wiring unit includes: a first power supply wiring connecting the first terminal and the first end of the switch, a second power supply wiring connecting the second end of the switch and the first input / output end of the bidirectional DC-DC converter, and a third power supply wiring connecting the second input / output end of the bidirectional DC-DC converter and the positive electrode of the power storage device, the power ground wiring unit connects the second terminal and the negative electrode of the power storage device and is connected to the ground end of the bidirectional DC-DC converter, the capacitor is connected between the second power supply wiring and the power ground wiring unit, and the third terminal is connected to the second power supply wiring, the signal ground wiring section is connected to the connection point of the power ground wiring section between the second terminal and a node to which the capacitor is connected in the power ground wiring section, and the at least one voltage detection circuit includes: a first voltage detection circuit that detects a voltage between the first power supply wiring and the signal ground wiring section; a second voltage detection circuit that detects a voltage between the second power supply wiring and the signal ground wiring section; and a third voltage detection circuit that detects a voltage between the third power supply wiring and the signal ground wiring section, and the at least one potential difference detection circuit includes: a first potential difference detection circuit that detects a potential difference between the connection point of the power ground wiring section and a node to which the first voltage detection circuit is connected in the signal ground wiring section; and a second potential difference detection circuit that detects a potential difference between a node to which the ground end of the bidirectional DC-DC converter is connected in the power ground wiring section and a node to which the second voltage detection circuit is connected in the signal ground wiring section.and a third potential difference detection circuit that detects a potential difference between a node to which the ground end of the bidirectional DC-DC converter is connected in the power ground wiring section and a node to which the third voltage detection circuit is connected in the signal ground wiring section, wherein the control circuit corrects the detected voltage of the first voltage detection circuit by the detected potential difference of the first potential difference detection circuit, corrects the detected voltage of the second voltage detection circuit by the detected potential difference of the second potential difference detection circuit, and corrects the detected voltage of the third voltage detection circuit by the detected potential difference of the third potential difference detection circuit.

15. The automotive power supply system according to claim 14, wherein the control circuit controls the switch to an ON state to charge the power storage device from the battery via the bidirectional DC-DC converter when a value obtained by correcting the detected voltage of the first voltage detection circuit by the detected potential difference of the first potential difference detection circuit is equal to or greater than a threshold value, and controls the switch to an OFF state to discharge the power storage device via the bidirectional DC-DC converter when a value obtained by correcting the detected voltage of the first voltage detection circuit by the detected potential difference of the first potential difference detection circuit is less than the threshold value.

16. The automotive power supply system according to claim 14 or 15, wherein the control circuit, when charging the power storage device, controls the bidirectional DC-DC converter based on a value obtained by correcting the detected voltage of the third voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit, and when discharging the power storage device, controls the bidirectional DC-DC converter based on a value obtained by correcting the detected voltage of the second voltage detection circuit by the detected potential difference of the at least one potential difference detection circuit.

17. The on-board power supply system according to any one of claims 13 to 16, further comprising a communication circuit that communicates with an ECU (Electronic Control Unit) of the electric vehicle, the connector further having a fourth terminal connected to the ECU, the communication circuit being connected between the fourth terminal and the control circuit and also connected to the signal ground wiring portion.

Images