Power supply system

Abstract

This prevents malfunctions caused by switch failures in the voltage detection circuit. [Solution] The power supply system 1 disclosed herein comprises a battery unit 10, a voltage detection circuit 100 connected to the battery unit 10, a voltage detection means 20 connected to the battery unit 10 via the voltage detection circuit 100, a control unit 110 that controls the ON / OFF state of switches in the voltage detection circuit 100, and an external power supply 60 connected to the voltage detection means 20. The voltage detection circuit 100 of this power supply system 1 comprises a first switch S1 to a seventh switch S7, a first resistor R1 to a sixth resistor R6, a first capacitor C1 to a second capacitor C2, and a first parallel line 70 to a fourth parallel line 76. The voltage detection circuit 100 is configured to self-diagnose whether or not a fault has occurred in the first switch S1 to the seventh switch S7 within the voltage detection circuit 100. This prevents malfunctions due to faults.

Description

TECHNICAL FIELD

[0001] The technology disclosed herein relates to a power supply system.

BACKGROUND ART

[0002] Power supply systems in which various circuits are attached to a battery unit are used in various electrical devices (for example, electric vehicles and the like). For example, this type of power supply system may be equipped with a voltage detection circuit that measures the voltage of the battery unit. Japanese Patent Laid-Open No. 2013-73824 discloses a power supply device provided with a voltage detection circuit.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] Incidentally, the voltage detection circuit of the power supply system is provided with a plurality of switches. The voltage detection circuit detects the voltage of the battery unit by appropriately switching ON / OFF of these switches. However, this type of switch may suffer a failure in which it does not switch ON even though it receives a signal (connection signal) instructing it to switch ON (hereinafter referred to as "open failure"). An open failure of this switch can cause malfunction due to erroneous voltage detection. The technology disclosed herein has been made to solve such a problem.

MEANS FOR SOLVING THE PROBLEMS

[0005] The power supply system disclosed herein comprises a battery unit including a plurality of battery cells, a voltage detection circuit connected to the battery unit, a voltage detection means connected to the battery unit via the voltage detection circuit, a control unit that controls the ON / OFF state of a switch in the voltage detection circuit, and an external power supply connected to the voltage detection means.The voltage detection circuit of this power supply system comprises a first resistor connected to the positive terminal of the battery unit, a second resistor connected to the negative terminal of the battery unit, a first parallel line connecting the first and second resistors, a first switch connected to the first resistor on the first parallel line, a third resistor connected to the first switch on the first parallel line, a fourth resistor connected to the third resistor on the first parallel line, a second switch connected between the fourth and second resistors on the first parallel line, and a positive terminal having one end connected between the first resistor and the first switch on the first parallel line and the other end connected to a voltage detection means. A polarity connection wire, a third switch provided on the positive polarity connection wire, a negative polarity connection wire having one end connected between the second switch and the second resistor on the first parallel wire, and the other end connected to the second switch and the second resistor on the first parallel wire, a fourth switch provided on the negative polarity connection wire, a second parallel wire having one end connected to the positive polarity connection wire on the voltage detection means side of the third switch and the other end connected to the negative polarity connection wire on the voltage detection means side of the fourth switch, a first capacitor installed on the second parallel wire, a second capacitor installed on the second parallel wire and located on the negative polarity connection wire side of the first capacitor, and the positive polarity connection wire on the voltage detection means side of one end of the second parallel wire A third parallel line having one end connected to the polarity connection line and the other end connected to the negative polarity connection line on the voltage detection means side of the other end of the second parallel line; a fifth resistor installed on the third parallel line; a sixth resistor installed on the third parallel line and located on the negative polarity connection line side of the fifth resistor; an intermediate connection line having one end connected between the third resistor and the fourth resistor in the first parallel line, an intermediate point connected between the first capacitor and the second capacitor in the second parallel line, and the other end connected between the fifth resistor and the sixth resistor in the third parallel line; and a positive polarity connection line installed on the positive polarity connection line and located on the voltage detection means side of the other end of the third parallel line The system includes a fifth switch located on the pressure detection means side, a sixth switch installed on the negative electrode connection line and located on the voltage detection means side of the other end of the third parallel line, a fourth parallel line having one end connected to an external power supply, a first connection point connected between the fifth switch and the voltage detection means on the positive electrode connection line, a second connection point connected to the other end of the negative electrode connection line, and the other end connected to ground, a seventh switch installed on the fourth parallel line and located between the first connection point and the external power supply, and a seventh resistor installed on the fourth parallel line and located between the seventh switch and the first connection point.

[0006] The power supply system with the above configuration is designed to self-diagnose whether or not an open fault has occurred in the switches (switches 1 to 7) within the voltage detection circuit. This prevents malfunctions caused by open faults. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a power supply system according to one embodiment. [Figure 2] Figure 2 is a schematic diagram showing the voltage detection circuit in Figure 1. [Figure 3] Figure 3 is a flowchart illustrating the diagnosis of switches 5 through 7. [Figure 4] Figure 4 is a schematic diagram illustrating the first voltage acquisition process. [Figure 5] Figure 5 is a schematic diagram illustrating the second voltage acquisition process. [Figure 6] Figure 6 is a flowchart illustrating the diagnosis of the first and second switches. [Figure 7] Figure 7 is a schematic diagram illustrating the energy storage procedure in the third voltage acquisition process. [Figure 8] Figure 8 is a schematic diagram illustrating the voltage measurement procedure in each of the third to eighth voltage acquisition steps. [Figure 9] Figure 9 is a schematic diagram illustrating the energy storage procedure in the fourth voltage acquisition process. [Figure 10] Figure 10 is a schematic diagram illustrating the energy storage procedure in the fifth voltage acquisition process. [Figure 11] Figure 11 is a schematic diagram illustrating the energy storage procedure in the sixth voltage acquisition process. [Figure 12] Figure 12 is a flowchart illustrating the diagnosis of the third and fourth switches. [Figure 13] Figure 13 is a schematic diagram illustrating the energy storage procedure in the seventh voltage acquisition process. [Figure 14]Figure 14 is a schematic diagram illustrating the energy storage procedure in the eighth voltage acquisition process. [Modes for carrying out the invention]

[0008] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. Note that the following embodiment is not intended to limit the technology disclosed herein. Each drawing is a schematic diagram and does not necessarily faithfully reflect an actual product. Furthermore, components and parts that perform the same function are appropriately denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0009] <Power System Configuration> Figure 1 is a schematic diagram showing a power supply system 1 according to this embodiment. As shown in Figure 1, the power supply system 1 is a system that supplies power to an external load L. The type and structure of the external load L are not limited to the technology disclosed herein. Examples of external load L include motors and inverters of electric vehicles.

[0010] The power supply system 1 shown in Figure 1 comprises a battery unit 10, a main line 80, a contactor 90, a voltage detection circuit 100, a voltage detection means 20, an external power supply 60, and a control unit 110.

[0011] 1. Battery unit 10 The battery unit 10 includes a plurality of battery cells 12. The detailed configuration of the battery cells 12 is not limited to the technology disclosed herein. Specific examples of battery cells 12 include secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries. As shown in Figure 1, the plurality of battery cells 12 are connected in series. The positive electrode of the battery cell 12 located at one end of the battery unit 10 (the upper end in Figure 1) is connected to the positive electrode main line 80p as the total positive terminal 10p. The negative electrode of the battery cell 12 located at the other end of the battery unit 10 (the lower end in Figure 1) is connected to the negative electrode main line 80n as the total negative terminal 10n.

[0012] 2. Main Line 80 The main line 80 is a conductive path that connects the battery unit 10 and the external load L. The main line 80 in the present embodiment includes a positive main line 80p and a negative main line 80n. The positive main line 80p connects the total positive terminal 10p of the battery unit 10 and the external load L. On the other hand, the negative main line 80n connects the total negative terminal 10n of the battery unit 10 and the external load L.

[0013] 3. Contactor 90 The contactor 90 is an element that switches connection and disconnection between the battery unit 10 and the external load L. The positive contactor 90p is disposed on the positive main line 80p. By turning ON the positive contactor 90p, the total positive terminal 10p of the battery unit 10 and the external load L are connected. On the other hand, the negative contactor 90n is disposed on the negative main line 80n. By turning ON the negative contactor 90n, the total negative terminal 10n of the battery unit 10 and the external load L are connected.

[0014] 4. Voltage Detection Circuit 100 The voltage detection circuit 100 is a circuit connected to the battery unit 10. The voltage detection circuit 100 in the present embodiment is connected between the positive main line 80p and the negative main line 80n. Specifically, the power supply system 1 according to the present embodiment includes a first detection line 82p branched from the positive main line 80p on the external load L side relative to the positive contactor 90p. This first detection line 82p is connected to the first resistor R1 (see FIG. 2) in the voltage detection circuit 100. The power supply system 1 also includes a second detection line 82n branched from the negative main line 80n on the external load L side relative to the negative contactor 90n. This second detection line 82n is connected to the second resistor R2 (see FIG. 2) in the voltage detection circuit 100. As will be described in detail later, the voltage detection circuit 100 according to the present embodiment includes a plurality of switches (a first switch S1 to a seventh switch S7). The voltage detection circuit 100 in the present embodiment is configured to be capable of self-diagnosing open failures of the first switch S1 to the seventh switch S7.

[0015] 5. Voltage detection means 20 The voltage detection means 20 is connected to the battery unit 10 via the voltage detection circuit 100. The voltage detection means 20 can detect the voltage values of the battery unit 10 and the external power supply 60 by switching the switches in the voltage detection circuit 100. The configuration of the voltage detection means 20 is not particularly limited, and a conventionally known device configuration can be adopted without particular limitation. For example, the voltage detection means 20 shown in FIG. 1 includes an AD converter 22 that converts analog signals into digital signals. This AD converter 22 converts the voltage value acquired as an analog signal into a digital signal and then transmits the digital signal to the control unit 110.

[0016] 6. Control unit 110 The control unit 110 controls the overall operation of the power supply system 1, including the charging and discharging of the battery unit 10. Specifically, the control unit 110 can control the ON / OFF state of the switches in the voltage detection circuit 100 (the first switch S1 to the seventh switch S7, described later). The control unit 110 can also control the ON / OFF state of the contactor 90. Information acquired by various sensors in the power supply system 1 is transmitted to the control unit 110. As described above, the voltage value acquired by the voltage detection means 20 (AD converter 22) is also transmitted to the control unit 110. Furthermore, the control unit 110 may be connected to a control device of an external device (for example, an ECU of an electric vehicle). This makes it easy to synchronize the operation of the external device with that of the power supply system 1. Note that the configuration of the control unit 110 is not limited to the technology disclosed herein. For example, a microcomputer can be used in the control unit 110. Specifically, the control unit 110 may include an I / F, a CPU, ROM, and RAM. The control unit 110 may consist of a single computer or multiple computers.

[0017] 7. External power supply 60 The external power supply 60 is a power supply connected to the voltage detection means 20. As will be described in detail later, it is connected to the fourth parallel line 76 within the voltage detection means 20 (see Figure 2). As shown in Figure 1, the external power supply 60 is a power source different from the battery unit 10. This external power supply 60 is preferably a power supply of 1V to 10V (for example, about 5V). Although not limited to the technology disclosed herein, the external power supply 60 can be a power supply for operating the control unit 110, etc. Alternatively, an external power supply 60 for connecting to the voltage detection means 20 may be provided separately.

[0018] 8. Detailed structure of the voltage detection circuit 100 Figure 2 is a schematic diagram showing the voltage detection circuit 100 in Figure 1. As shown in Figure 2, the voltage detection circuit 100 in this embodiment includes a positive terminal connection wire 30 connected to the positive terminal (total positive terminal 10p) of the battery unit 10, and a negative terminal connection wire 40 connected to the negative terminal (total negative terminal 10n) of the battery unit 10. Between the positive terminal connection wire 30 and the negative terminal connection wire 40, four connection wires (first parallel wires 70 to fourth parallel wires 76) are provided, connected in parallel to the battery unit 10. The voltage detection circuit 100 also includes first resistors R1 to seventh resistors R7, first switches S1 to seventh switches S7, and first capacitors C1 to third capacitors C3. The specific structure of each of these will be described below.

[0019] As shown in Figure 2, the first resistor R1 is connected to the positive terminal of the battery unit 10. Specifically, the first resistor R1 is connected to the total positive terminal 10p of the battery unit 10 via the first detection line 82p and the positive terminal main line 80p (see Figure 1). On the other hand, the second resistor R2 is connected to the negative terminal of the battery unit 10. Specifically, the second resistor R2 is connected to the total negative terminal 10n of the battery unit 10 via the second detection line 82n and the negative terminal main line 80n. As shown in Figure 2, the first resistor R1 and the second resistor R2 are connected by the first parallel line 70. As described above, the first parallel line 70 is a connecting line connected in parallel to the battery unit 10. This first parallel line 70 is formed at the position closest to the battery unit 10 among the first parallel lines 70 to the fourth parallel lines 76.

[0020] As shown in Figure 2, the first parallel line 70 has the first switch S1, third resistor R3, fourth resistor R4, and second switch S2 arranged in the order from the first resistor R1 to the second resistor R2. Specifically, the first switch S1 is connected to the first resistor R1 in the first parallel line 70. In other words, the first switch S1 is installed in the position closest to the positive main line 80p in the first parallel line 70. Next, the third resistor R3 is connected to the first switch S1 in the first parallel line 70. This third resistor R3 is set between one end 52 of the intermediate connection line 50 (described later) and the first switch S1. The fourth resistor R4 is connected to the third resistor R3 in the first parallel line 70. The fourth resistor R4 is located on the side of the second resistor R2 (negative main line 80n side) from one end 52 of the intermediate connection line 50. The second switch S2 is connected between the fourth resistor R4 and the second resistor R2 in the first parallel line 70. The second switch S2 is installed in the position closest to the negative terminal main line 80n on the first parallel line 70.

[0021] Next, the positive electrode connection wire 30 is the positive electrode connection wire that connects the first parallel wire 70 and the voltage detection means 20. That is, one end 32 of the positive electrode connection wire 30 is connected between the first resistor R1 and the first switch S1 in the first parallel wire 70. The other end 34 of the positive electrode connection wire 30 is connected to the voltage detection means 20. In other words, the positive electrode connection wire 30 branches off from the first parallel wire 70 and extends toward the voltage detection means 20. This positive electrode connection wire 30 is connected to the positive electrode (total positive terminal 10p) of the battery unit 10 via the first detection line 82p and the positive electrode main line 80p (see Figure 1). A third switch S3 is provided on the positive electrode connection wire 30. This third switch S3 is positioned closest to the first parallel wire 70 on the positive electrode connection wire 30.

[0022] The negative electrode connection wire 40 is the negative electrode connection wire that connects the first parallel wire 70 and the fourth parallel wire 76. One end 42 of the negative electrode connection wire 40 is connected between the second switch S2 and the second resistor R2 on the first parallel wire 70. The other end 44 of the negative electrode connection wire 40 is connected to the fourth parallel wire 76, which will be described later. Similar to the positive electrode connection wire 30 described above, the negative electrode connection wire 40 is also a connection wire that branches off from the first parallel wire 70. The negative electrode connection wire 40 is also connected to the negative electrode (total negative terminal 10n) of the battery unit 10 via the second detection line 82n and the negative electrode main line 80n. A fourth switch S4 is provided on the negative electrode connection wire 40. This fourth switch S4 is positioned closest to the first parallel wire 70 on the negative electrode connection wire 40.

[0023] Next, the voltage detection circuit 100 in this embodiment includes a second parallel wire 72 that connects the positive electrode connection wire 30 and the negative electrode connection wire 40. One end 72a of this second parallel wire 72 is connected to the positive electrode connection wire 30 on the voltage detection means 20 side of the third switch S3. The other end 72b of the second parallel wire 72 is connected to the negative electrode connection wire 40 on the voltage detection means 20 side of the fourth switch S4. The second parallel wire 72 is the second parallel wire formed when viewed from the battery unit 10 side. A first capacitor C1 is installed on this second parallel wire 72. In other words, the first capacitor C1 is connected to the positive electrode connection wire 30 on the voltage detection means 20 side of the third switch S3 via the second parallel wire 72. Furthermore, a second capacitor C2 is also installed on the second parallel wire 72. The second capacitor C2 is located on the negative electrode connection wire 40 side of the first capacitor C1. In other words, the second capacitor C2 is connected to the negative terminal connection line 40 on the voltage detection means 20 side of the fourth switch S4 via the second parallel line 72. When current flows from the battery unit 10 to the second parallel line 72, the first capacitor C1 and the second capacitor C2 on the second parallel line 72 are charged.

[0024] Furthermore, a third parallel wire 74 is also formed between the positive electrode connection wire 30 and the negative electrode connection wire 40. One end 74a of this third parallel wire 74 is connected to the positive electrode connection wire 30 on the voltage detection means 20 side than one end 72a of the second parallel wire 72. The other end 74b of the third parallel wire 74 is connected to the negative electrode connection wire 40 on the voltage detection means 20 side than the other end 72b of the second parallel wire 72. The third parallel wire 74 is the third parallel wire formed when viewed from the battery unit 10 side. A fifth resistor R5 is installed on this third parallel wire 74. In other words, the fifth resistor R5 is connected to the positive electrode connection wire 30 on the voltage detection means 20 side than one end 72a of the second parallel wire 72 via the third parallel wire 74. A sixth resistor R6 is also installed on the third parallel wire 74. This sixth resistor R6 is located on the negative electrode connection wire 40 side than the fifth resistor R5. In other words, the sixth resistor R6 is connected via the third parallel wire 74 to the negative terminal connection wire 40 on the voltage detection means 20 side of the other end 72b of the second parallel wire 72.

[0025] Furthermore, the voltage detection circuit 100 in this embodiment includes an intermediate connecting wire 50 that connects the first parallel line 70, the second parallel line 72, and the third parallel line 74. This intermediate connecting wire 50 is a connecting wire parallel to the positive terminal connecting wire 30 and the negative terminal connecting wire 40. One end 52 of the intermediate connecting wire 50 is connected between the third resistor R3 and the fourth resistor R4 in the first parallel line 70. The intermediate connecting wire 50 also has an intermediate point 56 connected between the first capacitor C1 and the second capacitor C2 in the second parallel line 72. The other end 54 of the intermediate connecting wire 50 is connected between the fifth resistor R5 and the sixth resistor R6 in the third parallel line 74.

[0026] Next, the fifth switch S5 is installed on the positive terminal connection line 30. The fifth switch S5 is located on the voltage detection means 20 side of one end 74a of the third parallel line 74. Specifically, the fifth switch S5 is provided between one end 74a of the third parallel line 74 and the first connection point 76c of the fourth parallel line 76, which will be described later. On the other hand, the sixth switch S6 is installed on the negative terminal connection line 40. This sixth switch S6 is located on the voltage detection means 20 side of the other end 74b of the third parallel line 74. Specifically, the sixth switch S6 is provided between the other end 74b of the third parallel line 74 and the other end 44 of the negative terminal connection line 40.

[0027] Next, the voltage detection circuit 100 according to this embodiment includes a fourth parallel line 76 that connects the external power supply 60, the positive electrode connection line 30, the negative electrode connection line 40, and the ground GND. That is, one end 76a of the fourth parallel line 76 is connected to the external power supply 60. The fourth parallel line 76 also has a first connection point 76c connected between the fifth switch S5 on the positive electrode connection line 30 and the voltage detection means 20. Furthermore, the fourth parallel line 76 has a second connection point 76d connected to the other end 44 of the negative electrode connection line 40. The other end 76b of the fourth parallel line 76 is connected to the ground GND. This fourth parallel line 76 is the fourth parallel line formed when viewed from the battery unit 10 side.

[0028] Furthermore, the fourth parallel line 76 is connected to the seventh switch S7, the seventh resistor R7, and the third capacitor C3, extending from the external power supply 60 towards ground GND. Specifically, the seventh switch S7 is located between the first connection point 76c and the external power supply 60. More precisely, the seventh switch S7 is located in the position closest to the external power supply 60 on the fourth parallel line 76. Next, the seventh resistor R7 is located between the seventh switch S7 and the first connection point 76c. In other words, the seventh resistor R7 is connected via the fourth parallel line 76 between the fifth switch S5 on the positive terminal connection line 30 and the voltage detection means 20. Finally, the third capacitor C3 is located between the first connection point 76c and the second connection point 76d.

[0029] <Procedure for detecting open faults> The configuration of the power supply system 1 according to this embodiment has been described above. The control unit 110 of the power supply system 1 with the above configuration can self-diagnose whether or not an open fault has occurred in the switches (first switch S1 to seventh switch S7) in the voltage detection circuit 100. This prevents malfunction of the power supply system 1 due to false voltage detection. The control unit 110 is configured to perform "diagnosis of switches 5 to 7", "diagnosis of switches 1 and 2", and "diagnosis of switches 3 and 4" individually. The respective diagnostic procedures will be described below.

[0030] 1. Diagnosis of switches 5 through 7 First, the procedure for diagnosing switches S5 through S7 will be explained. Figure 3 is a flowchart illustrating the diagnosis of switches S5 through S7. As shown in Figure 3, in diagnosing switches S5 through S7, the control unit 110 performs the following steps: first voltage acquisition step S10, first determination step S12, second voltage acquisition step S14, and second determination step S16. Each step will be explained below.

[0031] (First voltage acquisition process S10) Figure 4 is a schematic diagram illustrating the first voltage acquisition step S10. In the first voltage acquisition step S10, current is passed from the external power supply 60 to the fourth parallel line 76, and the first voltage V1, which is the voltage value in the fourth parallel line 76, is measured. In this first voltage acquisition step S10, as shown in Figure 4, the seventh switch S7 is turned ON, and the first switches S1 to the sixth switches S6 are turned OFF. As a result, current flows from the external power supply 60 to the fourth parallel line 76 (see X1 in Figure 4). As a result, the voltage detection means 20 detects the first voltage V1, which is the voltage value when current is passed from the external power supply 60 to the fourth parallel line 76. The voltage detection means 20 transmits this first voltage V1 to the control unit 110.

[0032] (First judgment step S12) In the first determination step S12, it is determined whether or not the first voltage V1 was detected in the first voltage acquisition step S10. Specifically, if the voltage detection means 20 does not detect the first voltage V1, it is understood that no current is flowing from the external power supply 60 to the fourth parallel line 76. In this case, the control unit 110 determines that the seventh switch S7 has an open fault (i.e., it does not turn ON even when a connection signal is received) (NO in S12). At this time, the control unit 110 performs the seventh switch abnormality determination S12a and then terminates the process. On the other hand, if the first voltage V1 is detected, the control unit 110 determines that the seventh switch S7 is normal and proceeds to the second voltage acquisition step S14 (YES in S12). In this specification, "no voltage detected" means that the detected voltage value is below a predetermined threshold (preferably 0.5V, more preferably 0.1V).

[0033] (Second voltage acquisition process S14) Figure 5 is a schematic diagram illustrating the second voltage acquisition step S14. In the second voltage acquisition step S14, current is passed from the external power supply 60 to the third parallel line 74 and the fourth parallel line 76, and the second voltage V2, which is the voltage value in the fourth parallel line 76, is measured. In this second voltage acquisition step S14, as shown in Figure 5, the fifth switch S5 to the seventh switch S7 are turned ON, and the first switch S1 to the fourth switch S4 are turned OFF. This creates a conductive path through which current flows from the external power supply 60 to the third parallel line 74, and a conductive path through which current flows from the external power supply 60 to the fourth parallel line 76 (see X2 in Figure 5). Here, the third parallel line 74 is provided with a fifth resistor R5 and a sixth resistor R6. Therefore, the voltage value of the current flowing through the fourth parallel line 76 (second voltage V2) is the value obtained by dividing the voltage from the external power supply 60 by the fifth resistor R5 and the sixth resistor R6. The voltage detection means 20 transmits this second voltage V2 to the control unit 110.

[0034] (Second judgment step S16) In the second determination step S16, it is determined whether the second voltage V2 is less than the first voltage V1 (V1 > V2). As described above, the second voltage V2 is the value obtained by dividing the voltage from the external power supply 60 by the fifth resistor R5 and the sixth resistor R6. Therefore, normally, the second voltage V2 will be smaller than the first voltage V1. On the other hand, if the second voltage V2 is greater than or equal to the first voltage V1 (V1 ≤ V2), it can be assumed that no voltage division occurs by the fifth resistor R5 and the sixth resistor R6, and therefore no current flows through the third parallel line 74. Based on this, the control unit 110 determines that at least one of the fifth switch S5 and the sixth switch S6 is open fault (NO in S16). In this case, the control unit 110 performs abnormality determination S16b for the fifth and sixth switches and then terminates the process. On the other hand, if the second voltage V2 is less than the first voltage V1 (V1 > V2), current is flowing from the external power supply 60 to the third parallel line 74, so the fifth switch S5 and the sixth switch S6 can be considered to be functioning normally. In this case, the control unit 110 performs normal certification S16a for the fifth switch S5 to the seventh switch S7 and then terminates processing (YES in S16).

[0035] As described above, the power supply system 1 according to this embodiment can perform self-diagnosis of the 5th switch S5 to the 7th switch S7 according to the procedure shown in Figures 3 to 5.

[0036] 2. Diagnosis of the first and second switches Next, the procedure for diagnosing the first switch S1 and the second switch S2 will be described. Figure 6 is a flowchart illustrating the diagnosis of the first switch S1 and the second switch S2. As shown in Figure 6, in diagnosing the first switch S1 and the second switch S2, the control unit 110 executes the third voltage acquisition step S20, the fourth voltage acquisition step S21, the third determination step S22, the fifth voltage acquisition step S23, the fourth determination step S24, the sixth voltage acquisition step S25, and the fifth determination step S26. Each step will be described below.

[0037] (Third voltage acquisition process S20) First, in the third voltage acquisition step S20, current is passed from the battery unit 10 to the second parallel line 72 to store energy in the first capacitor C1 and the second capacitor C2. Then, the third voltage V3, which is the voltage value when current is passed from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76, is measured. This will be explained in detail below.

[0038] Figure 7 is a schematic diagram illustrating the energy storage procedure in the third voltage acquisition step S20. As shown in Figure 7, in the energy storage process of the third voltage acquisition step S20, the third switch S3 and the fourth switch S4 are turned ON, and the first switches S1 to the second switches S2 and the fifth switches S5 to the seventh switches S7 are turned OFF. As a result, a conductive path is formed in the voltage detection circuit 100 through which current flows from the battery unit 10 to the second parallel line 72 (see X3 in Figure 7). As a result, the first capacitor C1 and the second capacitor C2 on the second parallel line 72 are charged.

[0039] Figure 8 is a schematic diagram illustrating the voltage measurement procedure in each of the third to eighth voltage acquisition steps. As shown in Figure 8, in the voltage measurement in the third voltage acquisition step S20, the fifth switch S5 and the sixth switch S6 are turned ON, and the first switches S1 to the fourth switches S4 and the seventh switch S7 are turned OFF. As a result, a conductive path is formed through which current flows from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76 (see X4 in Figure 8). This allows the voltage detection means 20 to detect the voltage value (here, the third voltage V3) when current flows from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76. The voltage detection means 20 transmits this third voltage V3 to the control unit 110.

[0040] In addition, a defect may occur in the third voltage acquisition step S20 in which the third voltage V3 is not detected. In this case, it is possible that the first capacitor C1 and the second capacitor C2 were not charged (power was not supplied from the battery unit 10 to the second parallel line 72) due to a failure of at least one of the third switch S3 and the fourth switch S4. It is also possible that power was not supplied from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76 due to a failure of the fifth switch S5 or the sixth switch S6. Therefore, if a failure to detect the third voltage V3 occurs, it is preferable for the control unit 110 to stop the following diagnoses and perform the "diagnoses of the fifth to seventh switches" and the "diagnoses of the third and fourth switches".

[0041] (Fourth voltage acquisition process S21) Next, in the fourth voltage acquisition step S21, current is passed from the battery unit 10 through both the first parallel line 70 and the second parallel line 72 to store energy in the first capacitor C1 and the second capacitor C2. Then, the fourth voltage V4, which is the voltage value when current is passed from the first capacitor C1 and the second capacitor C2 through the fourth parallel line 76, is measured. This will be explained in detail below.

[0042] Figure 9 is a schematic diagram illustrating the energy storage process in the fourth voltage acquisition step S21. As shown in Figure 9, in the fourth voltage acquisition step S21, the first switches S1 to the fourth switches S4 are turned ON, and the fifth switches S5 to the seventh switches S7 are turned OFF. As a result, the voltage detection circuit 100 forms a conductive path through which current flows from the battery unit 10 to the first parallel line 70, and a conductive path through which current flows from the battery unit 10 to the second parallel line 72 (see X5 in Figure 9). Consequently, the first capacitor C1 and the second capacitor C2 on the second parallel line 72 are charged with the voltage divided by the third resistor R3 and the fourth resistor R4 on the first parallel line 70.

[0043] Next, in the fourth voltage acquisition step S21, the fourth voltage V4 is measured by passing current from the first capacitor C1 and the second capacitor C2 through the fourth parallel line 76. The procedure for voltage measurement in this fourth voltage acquisition step S21 is the same as the voltage measurement in the third voltage acquisition step S20 described above. That is, in the voltage measurement in the fourth voltage acquisition step S21, as shown in Figure 8, the fifth switch S5 and the sixth switch S6 are turned ON, and the first switches S1 to the fourth switches S4 and the seventh switch S7 are turned OFF. As a result, the voltage detection means 20 can detect the voltage value when current is passed from the first capacitor C1 and the second capacitor C2 through the fourth parallel line 76. Here, the fourth voltage V4 measured in this step is the voltage value when the voltage from the battery unit 10 is divided by the third resistor R3 and the fourth resistor R4. The voltage detection means 20 transmits this fourth voltage V4 to the control unit 110.

[0044] (Third judgment step S22) In the third determination step S22, it is determined whether the fourth voltage V4 is less than the third voltage V3 (V3 > V4). As described above, the third voltage V3 is the voltage when the battery unit 10 stores energy in the first capacitor C1 and the second capacitor C2 via the second parallel line 72. On the other hand, the fourth voltage V4 is the voltage value when the first capacitor C1 and the second capacitor C2 are stored with the voltage divided by the third resistor R3 and the fourth resistor R4 on the first parallel line 70. For this reason, normally the fourth voltage V4 will be smaller than the third voltage V3. Therefore, if the fourth voltage V4 is less than the third voltage V3 (V3 > V4), the control unit 110 determines that the first switch S1 and the second switch S2 are normal (YES in S22). In this case, the control unit 110 performs normal certification S22a for the first switch S1 and the second switch S2 and then terminates the process. On the other hand, if the fourth voltage V4 is greater than or equal to the third voltage V3 (V3 ≤ V4), then in the fourth voltage acquisition step S21, since no voltage division occurs due to the third resistor R3 and the fourth resistor R4, it can be assumed that no current flows through the first parallel line 70. Based on this, the control unit 110 determines that at least one of the first switch S1 and the second switch S2 is open fault (NO in S22). In this case, the control unit 110 proceeds to the fifth voltage acquisition step S23 to identify the fault location in more detail.

[0045] (5th voltage acquisition process S23) In the fifth voltage acquisition step S23, current is passed from the battery unit 10 through the third resistor R3 on the first parallel line 70 and the second parallel line 72 to store energy in the first capacitor C1 and the second capacitor C2. Then, the fifth voltage V5, which is the voltage value when current is passed from the first capacitor C1 and the second capacitor C2 through the fourth parallel line 76, is measured. This will be explained in detail below.

[0046] Figure 10 is a schematic diagram illustrating the energy storage process in the fifth voltage acquisition step S23. As shown in Figure 10, in the energy storage process of the fifth voltage acquisition step S23, the first switch S1 and the third switches S3 to the fourth switches S4 are turned ON, and the second switch S2 and the fifth switches S5 to the seventh switches S7 are turned OFF. As a result, a conductive path (see X6a in Figure 10) is formed in the voltage detection circuit 100 through which current flows from the battery unit 10 to the second parallel line 72. In addition, in this step, a conductive path is also formed in the voltage detection circuit 100 through which current flows between one end 32 of the positive electrode connection line 30 and one end 52 of the intermediate connection line 50 (the region of the first parallel line 70 on the positive electrode connection line 30 side) (see X6b in Figure 10). And only the third resistor R3 is provided in this region of the first parallel line 70 on the positive electrode connection line 30 side. Therefore, in the fifth voltage acquisition step S23, the voltage divided by only the third resistor R3 is used to charge the first capacitor C1 and the second capacitor C2.

[0047] Next, in the fifth voltage acquisition step S23, current is passed from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76 to measure the voltage value. The procedure for this voltage measurement is the same as the voltage measurement in the third voltage acquisition step S20 and the fourth voltage acquisition step S21 (see Figure 8), so a redundant explanation is omitted. The fifth voltage V5 measured in the fifth voltage acquisition step S23 is the voltage value obtained when the voltage from the battery unit 10 is divided by only the third resistor R3. The voltage detection means 20 transmits this fifth voltage V5 to the control unit 110.

[0048] (Fourth judgment step S24) In the fourth determination step S24, it is determined whether the fifth voltage V5 is less than the third voltage V3 (V3 > V5). As described above, the fifth voltage V5 is the voltage value obtained when the voltage from the battery unit 10 is divided by the third resistor R3. Therefore, under normal circumstances, the fifth voltage V5 will be smaller than the third voltage V3. If the fifth voltage V5 is less than the third voltage V3 (V3 > V5), the control unit 110 determines that the first switch S1 is normal because current is flowing appropriately in the region on the positive electrode connection line 30 side of the first parallel line 70 (YES in S24). In this case, after performing the normal certification S24b for the first switch S1, the control unit 110 proceeds to the sixth voltage acquisition step S25. On the other hand, if the fifth voltage V5 is greater than or equal to the third voltage V3 (V3 ≤ V5), then no voltage division occurs due to the third resistor R3, and it can be assumed that no current flows through the conductive path X6b via the first parallel line 70 and the intermediate connecting line 50. Based on this, the control unit 110 determines that the first switch S1 is open fault (No. in S24). In this case, after performing abnormality determination S24a for the first switch S1, the control unit 110 proceeds to the sixth voltage acquisition step S25.

[0049] (Sixth voltage acquisition process S25) In the sixth voltage acquisition step S25, current is passed from the battery unit 10 through the fourth resistor R4 on the first parallel line 70 and the second parallel line 72 to store energy in the first capacitor C1 and the second capacitor C2. Then, the sixth voltage V6 is measured, which is the voltage value when current is passed from the first capacitor C1 and the second capacitor C2 through the fourth parallel line 76. This will be explained in detail below.

[0050] Figure 11 is a schematic diagram illustrating the energy storage process in the sixth voltage acquisition step S25. As shown in Figure 11, in the energy storage process of the sixth voltage acquisition step S25, the second switches S2 to the fourth switches S4 are turned ON, and the first switch S1 and the fifth switches S5 to the seventh switches S7 are turned OFF. This creates a conductive path in the voltage detection circuit 100 through which current flows from the battery unit 10 to the second parallel line 72 (see X7a in Figure 11). In addition, in this step, the voltage detection circuit 100 also creates a conductive path through which current flows between one end 52 of the intermediate connection line 50 and one end 42 of the negative electrode connection line 40 (the region of the first parallel line 70 on the negative electrode connection line 40 side) (see X7b in Figure 10). Only the fourth resistor R4 is provided in this region of the first parallel line 70 on the negative electrode connection line 40 side. Therefore, the first capacitor C1 and the second capacitor C2 are charged with the voltage divided by the fourth resistor R4.

[0051] Next, in the sixth voltage acquisition step S25, current is passed from the first capacitor C1 and the second capacitor C2 to the fourth parallel line 76 and the voltage is measured. The procedure for this voltage measurement is the same as the voltage measurement in the third voltage acquisition step S20 to the fifth voltage acquisition step S23 (see Figure 8). The sixth voltage V6 measured in the sixth voltage acquisition step S25 is the voltage value obtained when the voltage from the battery unit 10 is divided by only the fourth resistor R4. The voltage detection means 20 transmits this sixth voltage V6 to the control unit 110.

[0052] (Fifth judgment step S26) In the fifth determination step S26, it is determined whether the sixth voltage V6 is less than the third voltage V3 (V3 > V6). As described above, the sixth voltage V6 is the voltage value obtained when the voltage from the battery unit 10 is divided by the fourth resistor R4. Normally, this sixth voltage V6 is also smaller than the third voltage V3. Therefore, if the sixth voltage V6 is less than the third voltage V3 (V3 > V6), the control unit 110 determines that the second switch S2 is normal (YES in S26). In this case, the control unit 110 performs the normal certification S26a for the second switch S2 and then terminates the process. On the other hand, if the sixth voltage V6 is greater than or equal to the third voltage V3 (V3 ≤ V6), it can be considered that no voltage division by the fourth resistor R4 has occurred, and therefore no current is flowing in the region on the negative terminal connection line 40 side of the first parallel line 70. Based on these points, the control unit 110 determines that the second switch S2 has an open fault (NO in S26). In this case, the control unit 110 terminates processing after performing abnormality determination S26a for the second switch S2.

[0053] As described above, the power supply system 1 according to this embodiment can perform self-diagnosis of the first switch S1 and the second switch S2 according to the procedure shown in Figures 6 to 11. As mentioned above, if the determination results of both the fourth determination step S24 and the fifth determination step S26 are YES, then both the first switch S1 and the second switch S2 are determined to be normal. This determination result contradicts the determination in the third determination step S22 that "at least one of the first switch S1 and the second switch S2 is faulty" (NO in S22). In this case, it is preferable for the control unit 110 to repeat the above-described diagnostic procedure for the first switch S1 and the second switch S2 (third voltage acquisition step S20 to fifth determination step S26). This helps to suppress the occurrence of false detections.

[0054] 3. Diagnosis of the third and fourth switches Next, the procedure for diagnosing the third switch S3 and the fourth switch S4 will be described. Figure 12 is a flowchart illustrating the diagnosis of the third switch S3 and the fourth switch S4. As shown in Figure 12, in diagnosing the third switch S3 and the fourth switch S4, the control unit 110 executes the seventh voltage acquisition step S30, the sixth determination step S31, the eighth voltage acquisition step S32, and the seventh determination step S33. Each step will be described below.

[0055] (Seventh voltage acquisition process S30) In the seventh voltage acquisition step S30, current is passed from the battery unit 10 only to the first capacitor on the second parallel line 72 to store energy in the first capacitor C1. Then, the seventh voltage V7, which is the voltage value when current is passed from the first capacitor C1 to the fourth parallel line 76, is measured. This will be explained in detail below.

[0056] Figure 13 is a schematic diagram illustrating the energy storage process in the seventh voltage acquisition step S30. As shown in Figure 13, in the energy storage process of the seventh voltage acquisition step S30, the first switches S1 to the third switches S3 are turned ON, and the fourth switches S4 to the seventh switches S7 are turned OFF. This creates a conductive path in the voltage detection circuit 100 through which current flows from the battery unit 10 to the first parallel line 70 (see X8a in Figure 13). In addition, in this step, the voltage detection circuit 100 also creates a conductive path through which current flows between one end 72a of the second parallel line 72 and the midpoint 56 of the intermediate connection line 50 (the region of the second parallel line 72 on the positive electrode connection line 30 side) (see X8b in Figure 13). Only the first capacitor C1 is provided in this region of the second parallel line 72 on the positive electrode connection line 30 side. As a result, the power from the battery unit 10 is divided by the third resistor R3 and the fourth resistor R4, and then stored only in the first capacitor C1.

[0057] Next, in the seventh voltage acquisition step S30, current is passed from the first capacitor C1 to the fourth parallel line 76 and the voltage is measured. The procedure for this voltage measurement is the same as the voltage measurement in the third voltage acquisition steps S20 to the sixth voltage acquisition steps S25 described above (see Figure 8). Here, the seventh voltage V7 measured in the seventh voltage acquisition step S30 is the voltage value when the voltage from the battery unit 10 is divided by the third resistor R3 and the fourth resistor R4, and then stored only in the first capacitor C1. The voltage detection means 20 transmits this seventh voltage V7 to the control unit 110.

[0058] (Sixth judgment step S31) In the sixth determination step S31, it is determined whether or not the seventh voltage V7 was detected in the seventh voltage acquisition step S30. Specifically, if the seventh voltage V7 is not detected in the seventh voltage acquisition step S30, it can be assumed that no charge has been stored in the first capacitor C1, and therefore no current is flowing in the region on the positive terminal connection line 30 side of the second parallel line 72. Based on this, the control unit 110 determines that the third switch S3 has an open fault (NO in S31). In this case, the control unit 110 performs abnormality determination S31a for the third switch S3 and then proceeds to the eighth voltage acquisition step S32. On the other hand, if the seventh voltage V7 is detected, the control unit 110 determines that the third switch S3 is normal (YES in S31). In this case, the control unit 110 performs normal determination S31b for the third switch S3 and then proceeds to the eighth voltage acquisition step S32.

[0059] (8th voltage acquisition process S32) Next, in the eighth voltage acquisition step S32, current is passed from the battery unit 10 to the second capacitor on the first parallel line and the second parallel line 72 to store energy in the second capacitor C2, and then the eighth voltage V8 is measured when current is passed from the second capacitor C2 to the fourth parallel line 76. This will be explained in detail below.

[0060] Figure 14 is a schematic diagram illustrating the energy storage process in the eighth voltage acquisition step S32. As shown in Figure 14, in the energy storage process of the eighth voltage acquisition step S32, the first switch S1 to the second switch S2 and the fourth switch S4 are turned ON, and the third switch S3 and the fifth switch S5 to the seventh switch S7 are turned OFF. This creates a conductive path in the voltage detection circuit 100 through which current flows from the battery unit 10 to the first parallel line 70 (see X9a in Figure 14). In addition, in this step, the voltage detection circuit 100 also creates a conductive path through which current flows between the midpoint 56 of the intermediate connection line 50 and the other end 72b of the second parallel line 72 (the region of the second parallel line 72 on the negative electrode connection line 40 side) (see X9b in Figure 14). Only the second capacitor C2 is provided in this region of the second parallel line 72 on the negative electrode connection line 40 side. Therefore, the power from the battery unit 10 is divided by the third resistor R3 and the fourth resistor R4, and then stored only in the second capacitor C2.

[0061] Next, in the eighth voltage acquisition step S32, current is passed from the second capacitor C2 to the fourth parallel line 76 and the voltage is measured. The procedure for this voltage measurement is the same as the voltage measurement in the third voltage acquisition step S20 to the seventh voltage acquisition step S30 (see Figure 8). Here, the eighth voltage V8 measured in the eighth voltage acquisition step S32 is the voltage value when the voltage from the battery unit 10 is divided by the third resistor R3 and the fourth resistor R4, and then stored only in the second capacitor C2. The voltage detection means 20 transmits this eighth voltage V8 to the control unit 110.

[0062] (Seventh judgment step S33) In the seventh determination step S33, it is determined whether or not the eighth voltage V8 was detected in the eighth voltage acquisition step S32. Specifically, if the eighth voltage V8 was not detected in the eighth voltage acquisition step S32, it can be assumed that no charge has been stored in the second capacitor C2, and therefore no current is flowing in the region on the negative terminal connection line 40 side of the second parallel line 72. Based on this, the control unit 110 determines that the fourth switch S4 has an open fault (NO in S33). In this case, the control unit 110 terminates the process after performing an abnormality determination S33a for the fourth switch S4. On the other hand, if the eighth voltage V8 is detected, the control unit 110 determines that the fourth switch S4 is normal (YES in S33). In this case, the control unit 110 terminates the process after performing a normal determination S33b for the fourth switch S4.

[0063] As described above, the power supply system 1 according to this embodiment can perform self-diagnosis of the third switch S3 and the fourth switch S4 according to the procedure shown in Figures 12 to 14.

[0064] The procedure for fault detection in the power supply system 1 according to this embodiment has been described above. As described above, the power supply system 1 according to this embodiment can self-diagnose whether or not an open fault has occurred in the switches (first switch S1 to seventh switch S7) in the voltage detection circuit 100. This prevents malfunction of the power supply system 1 due to open faults in the switches.

[0065] The processing after detecting a switch malfunction is not limited to the technology disclosed herein. For example, the control unit 110 may prompt the user to repair the malfunction by notifying them of the switch malfunction. Alternatively, the control unit 110 may notify the control device of an external device not to use the voltage value of the battery unit 10 measured after the switch malfunction was confirmed for controlling the device.

[0066] <Other Embodiments> Although one embodiment of the technology disclosed herein has been described above, the above-described embodiment is merely illustrative and does not limit the technology described in the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

[0067] For example, in the power supply system 1 with the above configuration, a third capacitor C3 is provided between the first connection point 76c and the second connection point 76d of the fourth parallel line 76. However, this third capacitor C3 is not an essential component in the power supply system disclosed herein. As described above, in the power supply system 1 according to the first embodiment, faults in each switch are diagnosed by passing current through the fourth parallel line 76 and detecting the voltage with the voltage detection means 20. And even if the third capacitor C3 is not installed, current can still be passed through the fourth parallel line 76. Therefore, even if the third capacitor C3 is not placed on the fourth parallel line 76, fault diagnosis of each switch in the voltage detection circuit 100 can be performed. However, as in the embodiment described above, if the third capacitor C3 is placed on the fourth parallel line 76, the voltage value to the voltage detection means 20 can be stabilized and malfunctions due to noise can be suppressed. For this reason, it is preferable to have the third capacitor C3 installed between the first connection point 76c and the second connection point 76d.

[0068] Furthermore, the technologies disclosed herein encompass the forms described in the following sections.

[0069] [Item 1] A battery unit containing multiple battery cells, A voltage detection circuit connected to the aforementioned battery unit, A voltage detection means connected to the battery unit via the voltage detection circuit, A control unit that controls the ON / OFF state of the switch in the voltage detection circuit, An external power supply connected to the voltage detection means, Equipped with, The voltage detection circuit is A first resistor connected to the positive terminal of the battery unit, A second resistor connected to the negative terminal of the aforementioned battery unit, A first parallel wire connecting the first resistor and the second resistor, A first switch connected to the first resistor in the first parallel line, A third resistor connected to the first switch in the first parallel line, A fourth resistor connected to the third resistor in the first parallel line, A second switch connected between the fourth resistor and the second resistor in the first parallel line, A positive terminal connection wire having one end connected between the first resistor and the first switch in the first parallel line, and the other end connected to the voltage detection means, A third switch is provided on the positive electrode connection line, A negative terminal connecting wire having one end and the other end connected between the second switch and the second resistor in the first parallel line, A fourth switch is provided on the negative terminal connection line, A second parallel wire having one end connected to the positive electrode connection wire on the voltage detection means side of the third switch, and the other end connected to the negative electrode connection wire on the voltage detection means side of the fourth switch, The first capacitor installed on the second parallel line, A second capacitor is installed on the second parallel line and is located on the negative terminal connection line side of the first capacitor, A third parallel line having one end connected to the positive electrode connection line on the voltage detection means side of one end of the second parallel line, and the other end connected to the negative electrode connection line on the voltage detection means side of the other end of the second parallel line, The fifth resistor installed on the third parallel line, A sixth resistor is installed on the third parallel line and is located on the negative terminal connection line side of the fifth resistor, An intermediate connecting wire having one end connected between the third resistor and the fourth resistor in the first parallel wire, an intermediate point connected between the first capacitor and the second capacitor in the second parallel wire, and the other end connected between the fifth resistor and the sixth resistor in the third parallel wire, A fifth switch is installed on the positive electrode connection line and is located on the voltage detection means side of one end of the third parallel line, A sixth switch is installed on the negative terminal connection line and is located on the voltage detection means side of the other end of the third parallel line, A fourth parallel wire having one end connected to the external power supply, a first connection point connected between the fifth switch and the voltage detection means on the positive electrode connection wire, a second connection point connected to the other end of the negative electrode connection wire, and the other end connected to ground, A seventh switch is installed on the fourth parallel line and is located between the first connection point and the external power supply, A seventh resistor is installed on the fourth parallel line and is located between the seventh switch and the first connection point, A power supply system equipped with this feature.

[0070] [Item 2] The power supply system according to item 1, wherein the voltage detection circuit is installed on the fourth parallel line and further comprises a third capacitor located between the first connection point and the second connection point.

[0071] [Item 3] The power supply system according to item 1 or 2, wherein the voltage detection means comprises an AD converter that converts an analog signal into a digital signal.

[0072] [Item 4] The control unit, A first voltage acquisition step involves flowing current from the external power supply to the fourth parallel line and measuring the first voltage V1, which is the voltage value in the fourth parallel line. A first determination step in which it is determined whether or not the first voltage V1 is detected in the first voltage acquisition step, and if the first voltage V1 is not detected, it is determined that the seventh switch is faulty. A power system configured to perform the following, as described in any one of items 1-3.

[0073] [Item 5] The control unit, A second voltage acquisition step involves flowing current from the external power supply through the third parallel line and the fourth parallel line, and measuring the second voltage V2, which is the voltage value in the fourth parallel line. A second determination step in which the second voltage V2 is determined to be less than the first voltage V1, and if the second voltage V2 is equal to or greater than the first voltage V1, the second determination step in which at least one of the fifth switch and the sixth switch is determined to be faulty. A power supply system as described in item 4, configured to perform the following actions.

[0074] [Item 6] The control unit, A third voltage acquisition step involves measuring a third voltage V3, which is the voltage value obtained when current is passed from the first capacitor and the second capacitor through the fourth parallel line after the first capacitor and the second capacitor have been charged by passing current through the second parallel line from the battery unit. A fourth voltage acquisition step involves measuring a fourth voltage V4, which is the voltage value obtained when current is passed from the first capacitor and the second capacitor through the fourth parallel line, after the battery unit has been used to store energy in the first and second capacitors by passing current through both the first and second capacitors. A third determination step in which the fourth voltage is determined to be less than the third voltage, and if the fourth voltage V4 is equal to or greater than the third voltage V3, it is determined that at least one of the first switch and the second switch is faulty. A power system configured to perform the following, as described in any one of items 1 through 5.

[0075] [Item 7] The control unit, A fifth voltage acquisition step is to measure the fifth voltage V5, which is the voltage value when current is passed from the first capacitor and the second capacitor through the fourth parallel line, after the battery unit has passed current through the third resistor and the second parallel line on the first parallel line to store energy in the first capacitor and the second capacitor. A fourth determination step in which the fifth voltage V5 is determined to be less than the third voltage V3, and if the fifth voltage V5 is equal to or greater than the third voltage V3, the first switch is determined to be faulty. A power supply system as described in item 6, configured to perform the following actions.

[0076] [Item 8] The control unit, A sixth voltage acquisition step is performed in which, after current is passed from the battery unit through the fourth resistor R4 on the first parallel line and through each of the second parallel lines to store energy in the first capacitor and the second capacitor, a sixth voltage V6 is measured, which is the voltage value when current is passed from the first capacitor and the second capacitor through the fourth parallel line. A fifth determination step in which the sixth voltage V6 is determined to be less than the third voltage V3, and if the sixth voltage V6 is equal to or greater than the third voltage V3, the second switch is determined to be faulty. A power supply system as described in item 6 or 7, configured to perform the following:

[0077] [Item 9] The control unit, A seventh voltage acquisition step is performed in which, after current is passed from the battery unit to the first capacitor of the second parallel line to store energy in the first capacitor, the voltage value of the seventh voltage V7 when current is passed from the first capacitor to the fourth parallel line is measured, A sixth determination step in which it is determined whether the seventh voltage V7 is detected in the seventh voltage acquisition step, and if the seventh voltage V7 is not detected, it is determined that the third switch is faulty. A power system configured to perform the following, as described in any one of items 1 through 8.

[0078] [Item 10] The control unit, An eighth voltage acquisition step is performed to measure the eighth voltage V8 when current is passed from the second capacitor to the fourth parallel line after current has been passed from the second capacitor to the fourth parallel line by passing current from the battery unit to the second capacitor to store energy in the second capacitor, A seventh determination step in which it is determined whether or not the eighth voltage V8 was detected in the eighth voltage acquisition step, and if the eighth voltage V8 was not detected, it is determined that the fourth switch is faulty. A power system configured to perform the following, as described in any one of items 1 through 9. [Explanation of Symbols]

[0079] 1. Power System 10 Battery Units 10n total negative terminal 10-pin total positive terminal 12 battery cells 22 AD Converter 30 Positive electrode connection wire 40 Negative electrode connection wire 50 Intermediate connection line 56 Midpoint 60 External power supply 70 First Parallel Line 72 Second Parallel Line 74 Third Parallel Line 76. Fourth Parallel Line 80 Mainline 90 Contactor 100 Voltage detection circuit 110 Control Unit C1 First capacitor C2 Second capacitor C3 Third capacitor GND (Ground) L External load R1 is the first resistor. R2 2nd resistor R3 3rd resistor R4 4th resistor R5 5th resistor R6 6th resistor R7 7th resistor S1 1st Switch S2 Second Switch S3 3rd switch S4 4th Switch S5 Switch 5 S6 6th Switch S7 Switch 7

Claims

1. A battery unit containing multiple battery cells, A voltage detection circuit connected to the aforementioned battery unit, A voltage detection means connected to the battery unit via the voltage detection circuit, A control unit that controls the ON / OFF state of the switch in the voltage detection circuit, An external power supply connected to the voltage detection means, Equipped with, The voltage detection circuit is A first resistor connected to the positive terminal of the battery unit, A second resistor connected to the negative terminal of the aforementioned battery unit, A first parallel wire connecting the first resistor and the second resistor, A first switch connected to the first resistor in the first parallel line, A third resistor connected to the first switch in the first parallel line, A fourth resistor connected to the third resistor in the first parallel line, A second switch connected between the fourth resistor and the second resistor in the first parallel line, A positive electrode connection wire having one end connected between the first resistor and the first switch in the first parallel line, and the other end connected to the voltage detection means, A third switch provided on the positive terminal connection line, A negative terminal connecting wire having one end and the other end connected between the second switch and the second resistor in the first parallel line, A fourth switch is provided on the negative terminal connection line, A second parallel wire having one end connected to the positive electrode connection wire on the voltage detection means side of the third switch, and the other end connected to the negative electrode connection wire on the voltage detection means side of the fourth switch, The first capacitor installed on the second parallel line, A second capacitor is installed on the second parallel line and is located on the negative terminal connection line side of the first capacitor, A third parallel line having one end connected to the positive electrode connection line on the voltage detection means side of one end of the second parallel line, and the other end connected to the negative electrode connection line on the voltage detection means side of the other end of the second parallel line, The fifth resistor installed on the third parallel line, A sixth resistor is installed on the third parallel line and is located on the negative terminal connection line side of the fifth resistor, An intermediate connecting wire having one end connected between the third resistor and the fourth resistor in the first parallel wire, an intermediate point connected between the first capacitor and the second capacitor in the second parallel wire, and the other end connected between the fifth resistor and the sixth resistor in the third parallel wire, A fifth switch is installed on the positive electrode connection line and is located on the voltage detection means side of one end of the third parallel line, A sixth switch is installed on the negative terminal connection line and is located on the voltage detection means side of the other end of the third parallel line, A fourth parallel line having one end connected to the external power supply, a first connection point connected between the fifth switch and the voltage detection means on the positive electrode connection line, a second connection point connected to the other end of the negative electrode connection line, and the other end connected to ground, A seventh switch is installed on the fourth parallel line and is located between the first connection point and the external power supply, A seventh resistor is installed on the fourth parallel line and is located between the seventh switch and the first connection point, A power supply system equipped with this feature.

2. The power supply system according to claim 1, wherein the voltage detection circuit is installed on the fourth parallel line and further comprises a third capacitor located between the first connection point and the second connection point.

3. The power supply system according to claim 1 or 2, wherein the voltage detection means includes an AD converter that converts an analog signal into a digital signal.

4. The control unit, A first voltage acquisition step involves flowing current from the external power supply to the fourth parallel line and measuring the first voltage V1, which is the voltage value in the fourth parallel line. A first determination step in which it is determined whether or not the first voltage V1 is detected in the first voltage acquisition step, and if the first voltage V1 is not detected, it is determined that the seventh switch is faulty. A power supply system according to claim 1 or 2, configured to perform the following:

5. The control unit, A second voltage acquisition step involves flowing current from the external power supply through the third parallel line and the fourth parallel line, and measuring the second voltage V2, which is the voltage value in the fourth parallel line. A second determination step of determining whether the second voltage V2 is less than the first voltage V1, and if the second voltage V2 is equal to or greater than the first voltage V1, determining that at least one of the fifth switch and the sixth switch is faulty. The power supply system according to claim 4, configured to perform the following:

6. The control unit, A third voltage acquisition step involves measuring a third voltage V3, which is the voltage value obtained when current is passed from the first capacitor and the second capacitor through the fourth parallel line after the first capacitor and the second capacitor have been charged by passing current through the second parallel line from the battery unit. A fourth voltage acquisition step involves measuring a fourth voltage V4, which is the voltage value obtained when current is passed from the first capacitor and the second capacitor through the fourth parallel line, after the battery unit has been used to store energy in the first and second capacitors by passing current through both the first and second capacitors. A third determination step in which the fourth voltage is determined to be less than the third voltage, and if the fourth voltage V4 is equal to or greater than the third voltage V3, it is determined that at least one of the first switch and the second switch is faulty. A power supply system according to claim 1 or 2, configured to perform the following:

7. The control unit, A fifth voltage acquisition step is to measure the fifth voltage V5, which is the voltage value when current is passed from the first capacitor and the second capacitor through the fourth parallel line, after the battery unit has passed current through the third resistor and the second parallel line on the first parallel line to store energy in the first capacitor and the second capacitor. A fourth determination step in which the fifth voltage V5 is determined to be less than the third voltage V3, and if the fifth voltage V5 is equal to or greater than the third voltage V3, the first switch is determined to be faulty. The power supply system according to claim 6, configured to perform the following:

8. The control unit, A sixth voltage acquisition step is performed in which, after current is passed from the battery unit through the fourth resistor R4 on the first parallel line and the second parallel line to store energy in the first capacitor and the second capacitor, a sixth voltage V6 is measured, which is the voltage value when current is passed from the first capacitor and the second capacitor through the fourth parallel line. A fifth determination step in which the sixth voltage V6 is determined to be less than the third voltage V3, and if the sixth voltage V6 is equal to or greater than the third voltage V3, the second switch is determined to be faulty. The power supply system according to claim 6, configured to perform the following:

9. The control unit, A seventh voltage acquisition step is performed in which, after current is passed from the battery unit to the first capacitor of the second parallel line to store energy in the first capacitor, a seventh voltage V7 is measured, which is the voltage value when current is passed from the first capacitor to the fourth parallel line. A sixth determination step in which it is determined whether or not the seventh voltage V7 was detected in the seventh voltage acquisition step, and if the seventh voltage V7 was not detected, it is determined that the third switch is faulty. A power supply system according to claim 1 or 2, configured to perform the following:

10. The control unit, An eighth voltage acquisition step is performed to measure the eighth voltage V8 when current is passed from the second capacitor to the fourth parallel line after current has been passed from the second capacitor to the fourth parallel line by passing current from the battery unit to the second capacitor to store energy in the second capacitor, A seventh determination step in which it is determined whether or not the eighth voltage V8 is detected in the eighth voltage acquisition step, and if the eighth voltage V8 is not detected, it is determined that the fourth switch is faulty. A power supply system according to claim 1 or 2, configured to perform the following:

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