Distribution device

Abstract

To provide a distribution device which can be further improved in reliability.SOLUTION: A distribution device includes: terminals 60a, 60b connected to a first battery 11; terminals 60c, 60d connected to a second battery 12; terminals 60e, 60f connected to a quick charger 30; first to fifth lines L1 to L5 connecting sections; a first switch SW1 on the third line L3; a second switch SW2 on the fourth line L4; a third switch SW3 on the fifth line L5; and a control unit 63 that controls the first to third switches SW1 to SW3. The control unit 63 includes: a voltage measurement unit 63c that measures the voltages of the first line L1 and the second line L2; a current measurement unit 63a that measures the current on the fourth line L4; and a failure determining unit 63d that determines a failure in the first to third switches SW1 to SW3 on the basis of the measurement results obtained by the voltage measurement unit 63c and the current measurement unit 63a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to power distribution devices. [Background technology]

[0002] In recent years, with consideration for the environment, electric vehicles equipped with high-voltage batteries such as EVs (Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles) have appeared. The voltage of these electric vehicles is increasing year by year, for example from about 400V to about 800V. As the voltage of electric vehicles increases, the standard voltage of chargers for electric vehicles is also increasing, making them compatible with vehicles equipped with high-voltage batteries. However, chargers with higher standards require a lot of power, making them difficult to install in areas with poor power conditions, and it is also difficult to replace all currently installed chargers so that they can handle a voltage of, for example, 800V.

[0003] In response to this, a power distribution device has been proposed that allows switching between direct connection and parallel connection of secondary batteries mounted on electric vehicles (see, for example, Patent Document 1). With this power distribution device, by switching to a parallel connection during charging, the voltage during charging can be made lower than when the batteries are connected in series. Therefore, a high-voltage electric vehicle can be charged even with a low voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-63722 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the power distribution device disclosed in Patent Document 1, if a failure occurs in the switch that switches between series connection and parallel connection, a short circuit or the like occurs in the secondary battery, reducing reliability. In particular, when multiple switches are used, identifying which switch has failed leads to improved reliability.

[0006] Therefore, an object of the present invention is to provide a power distribution device that can further improve reliability. [Means for solving the problem]

[0007] In order to solve the above problem, a power distribution device according to an embodiment of the present disclosure includes a first battery positive terminal and a first battery negative terminal connected to a positive electrode and a negative electrode of a first battery, respectively, a second battery positive terminal and a second battery negative terminal connected to a positive electrode and a negative electrode of a second battery, respectively, a charger positive terminal and a charger negative terminal connected to a positive electrode and a negative electrode of a charger, respectively, a first line connecting the first battery positive terminal and the charger positive terminal, a second line connecting the second battery negative terminal and the charger negative terminal, a third line connecting the second battery positive terminal and the first battery negative terminal, a first switch controlling conduction and interruption in the third line, and a second line connecting the second battery positive terminal and the first line. the first battery negative terminal and a second switch configured to control the conduction and interruption of the fourth line; a fifth line configured to connect the second line and the first battery negative terminal; a third switch configured to control the conduction and interruption of the fifth line; and control means configured to control the conduction and interruption states of the first switch, the second switch, and the third switch, wherein the control means has a voltage measurement means configured to measure a voltage between the first line and the second line, a current measurement means configured to measure a current in one of the fourth line and the fifth line, and a failure determination means configured to determine a failure of the first switch, the second switch, and the third switch based on the voltage measured by the voltage measurement means and the current measured by the current measurement means. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a power distribution device that can achieve further improved reliability. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a secondary battery system including a power distribution device according to an embodiment of the present invention. [Diagram 2] 2 is a first state diagram showing a control state by a SW control unit shown in FIG. 1. [Diagram 3] 1. FIG. 4 is a second state diagram showing a control state by the SW control unit shown in FIG. [Figure 4] 4 is a first table showing a failure determination method performed by the failure determination unit shown in FIG. 1; [Diagram 5] 10 is a second diagram showing a failure determination method performed by the failure determination unit shown in FIG. [Figure 6] FIG. 1 is a first state diagram illustrating current flow under each fault condition. [Figure 7] FIG. 4 is a second state diagram illustrating current flow under each fault condition. [Figure 8] FIG. 4 is a third state diagram illustrating current flow under each fault condition. [Figure 9] FIG. 4 is a fourth state diagram showing current flow under each fault condition. [Figure 10] FIG. 5 is a fifth state diagram showing current flow under each fault condition. [Figure 11] FIG. 6 is a sixth state diagram showing current flow under each fault condition. [Figure 12] FIG. 7 is a seventh state diagram showing current flow under each fault condition. [Figure 13] FIG. 13 is an eighth state diagram showing current flow under each fault condition. [Figure 14] FIG. 2 is a configuration diagram showing a secondary battery system showing a first modified example of the present embodiment. [Figure 15] FIG. 11 is a configuration diagram showing a secondary battery system showing a second modified example of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be modified as appropriate within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are appropriately applied to the details of the omitted technologies within the scope of the contents described below.

[0011] Fig. 1 is a configuration diagram showing a secondary battery system including a power distribution device according to an embodiment of the present invention. The secondary battery system 1 shown in Fig. 1 includes a high-voltage battery 10, a charging junction box (hereinafter referred to as J / B) 20, a quick charger (charger) 30, a high-voltage J / B 40, a high-voltage load 50, and a power distribution device 60.

[0012] The high-voltage battery 10 includes a first battery 11, a second battery 12, a first monitoring unit 13, a second monitoring unit 14, and a battery ECU (Electronic Control Unit) 15.

[0013] The first battery 11 and the second battery 12 are configured by secondary batteries such as chargeable and dischargeable lithium ion batteries. The first battery 11 and the second battery 12 are each capable of supplying a high voltage such as 400V in order to drive a high voltage load 50 in an electric vehicle, for example. In this embodiment, the first battery 11 and the second battery 12 are assumed to have the same voltage.

[0014] The first monitoring unit 13 monitors the voltage, current, and temperature of the first battery 11. The second monitoring unit 14 monitors the voltage, current, and temperature of the second battery 12. The battery ECU 15 calculates the charging rates of the first battery 11 and the second battery 12 based on information from the first monitoring unit 13 and the second monitoring unit 14. The battery ECU 15 may also calculate the deterioration levels and detect abnormalities of the first battery 11 and the second battery 12.

[0015] The charging J / B 20 is a relay device interposed between the power distribution device 60 and the rapid charger 30. The charging J / B 20 includes a first charging relay 21 and a second charging relay 22. The first charging relay 21 controls the connection between the positive electrode side of the rapid charger 30 and the power distribution device 60. The second charging relay 22 controls the connection between the negative electrode side of the rapid charger 30 and the power distribution device 60. The first charging relay 21 and the second charging relay 22 may be either of a mechanical contact type or a semiconductor type. The same applies to first and second high-voltage relays 41, 42 and first to third switches SW1 to SW3 described later.

[0016] The quick charger 30 supplies power for charging the first battery 11 and the second battery 12 through the charging J / B 20 and the power distribution device 60. The quick charger 30 may supply power with a voltage of 400V, for example, or may supply power with a voltage of 800V. The power distribution device 60 determines whether the first battery 11 and the second battery 12 are connected in series or in parallel according to the supply power, and charges the first battery 11 and the second battery 12 in that connection state. Note that the secondary battery system 1 according to this embodiment is assumed to be charged by the quick charger 30, but is not limited thereto, and may be charged by a general charger that is not quick.

[0017] The high voltage J / B 40 is a relay device interposed between the power distribution device 60 and the high voltage load 50. The high voltage J / B 40 includes a first high voltage relay 41 and a second high voltage relay 42. The first high voltage relay 41 controls the connection between the positive electrode side of the high voltage load 50 and the power distribution device 60. The second high voltage relay 42 controls the connection between the negative electrode side of the high voltage load 50 and the power distribution device 60. The high voltage load 50 is a motor or the like that generates driving force for a vehicle.

[0018] The power distribution device 60 switches the connection state of the first battery 11 and the second battery 12 between a series state and a parallel state when charging from the quick charger 30 via the charging J / B 20, or when discharging to the high-voltage load 50 via the high-voltage J / B 40.

[0019] The power distribution device 60 has a plurality of terminals 60a to 60h. The first battery positive terminal 60a and the first battery negative terminal 60b are terminals connected to the positive and negative electrodes of the first battery 11, respectively. The second battery positive terminal 60c and the second battery negative terminal 60d are terminals connected to the positive and negative electrodes of the second battery 12, respectively. The charger positive terminal 60e and the charger negative terminal 60f are terminals connected to the positive and negative electrodes of the quick charger 30, respectively. The load positive terminal 60g and the load negative terminal 60h are terminals connected to the positive and negative electrodes of the high-voltage load 50, respectively.

[0020] Furthermore, the power distribution device 60 includes a plurality of lines L1 to L7, a plurality of switches SW1 to SW3, a current sensor 61, a voltage sensor 62, and a control unit (control means) 63.

[0021] The first line L1 connects the first battery positive terminal 60a and the charger positive terminal 60e. The second line L2 connects the second battery negative terminal 60d and the charger negative terminal 60f. The third line L3 connects the second battery positive terminal 60c and the first battery negative terminal 60b. As described later, one end of the third line L3 (from the terminal 60c to the connection point P1 in FIG. 1) is shared with the fourth line L4, and the other end (from the terminal 60b to the connection point P2 in FIG. 1) is shared with the fifth line L5. The third line L3 connects the first battery negative terminal 60b and the second battery positive terminal 60c through the shared parts L34 and L35. The first switch SW1 controls the conduction and cutoff of the third line L3, and is provided at a position of the third line L3 excluding the shared parts L34 and L35.

[0022] The fourth line L4 connects the second battery positive terminal 60c and the first line L1. One end of the fourth line L4 is a common portion L34 with the third line L3. The second switch SW2 controls the conduction and cutoff of the fourth line L4, and is provided at a position of the fourth line L4 excluding the common portion L34 with the third line L3.

[0023] The fifth line L5 connects the second line L2 and the first battery negative terminal 60b. The other end of the fifth line L5 is a common portion L35 with the third line L3. The third switch SW3 controls the conduction and cutoff of the fifth line L5, and is provided at a position of the fifth line L5 excluding the common portion L35 with the third line L3.

[0024] The sixth line L6 connects a connection point P4 of the first line L1, which is located closer to the charger positive terminal 60e than the connection point P3 with the fourth line L4, to the load positive terminal 60g. The seventh line L7 connects a connection point P6 of the second line L2, which is located closer to the charger negative terminal 60f than the connection point P5 with the fifth line L5, to the load negative terminal 60h.

[0025] The current sensor 61 is provided on the fourth line L4 and outputs a signal corresponding to the current in the fourth line L4. In this embodiment, the current sensor 61 is provided in a common portion L34 of the fourth line L4 with the third line L3.

[0026] The voltage sensor 62 outputs a signal corresponding to the potential difference between the first line L1 and the second line L2. More specifically, the voltage sensor 62 outputs a signal corresponding to the potential difference between a connection point P7 located between the connection points P3 and P4 on the first line L1 and a connection point P8 located between the connection points P5 and P6 on the second line L2.

[0027] The control unit 63 controls the entire power distribution device 60, and includes a current measurement unit (current measurement means) 63a, a SW control unit 63b, a voltage measurement unit (voltage measurement means) 63c, and a fault determination unit (fault determination means) 63d.

[0028] The current measurement unit 63a measures the current in the fourth line L4 (particularly the common portion L34) in response to a signal from the current sensor 61. The voltage measurement unit 63c measures a voltage corresponding to the potential difference between the first line L1 and the second line L2 in response to a signal from the voltage sensor 62.

[0029] The SW control unit 63b controls the conductive state (ON) and the cut-off state (OFF) of the first switch SW1, the second switch SW2, and the third switch SW3. FIG. 2 and FIG. 3 are state diagrams showing the control state by the SW control unit 63b shown in FIG. 1. First, as shown in FIG. 2, when the SW control unit 63b wants to connect the first battery 11 and the second battery 12 in series, the SW control unit 63b turns on the first switch SW1 and turns off the second switch SW2 and the third switch SW3. As a result, for example, during charging, a route (see the thick line) of the first line L1, the first battery 11, the third line L3, the second battery 12, and the second line L2 is formed. Therefore, the first battery 11 and the second battery 12 are in a series state. On the other hand, as shown in FIG. 3, when the SW control unit 63b wants to connect the first battery 11 and the second battery 12 in parallel, the SW control unit 63b turns off the first switch SW1 and turns on the second switch SW2 and the third switch SW3. As a result, during charging, a route (see thick line) of the first line L1, the first battery 11, the fifth line L5, and the second line L2, and a route (see thick line) of the first line L1, the fourth line L4, the second battery 12, and the second line L2 are formed. Therefore, the first battery 11 and the second battery 12 are in a parallel state.

[0030] The failure determination unit 63d determines whether or not there is a failure in the first switch SW1, the second switch SW2, or the third switch SW3. The failure determination unit 63d determines whether or not there is a failure in the first switch SW1, the second switch SW2, or the third switch SW3, based on the voltage measured by the voltage measurement unit 63c and the current measured by the current measurement unit 63a.

[0031] For example, the first switch SW1, the second switch SW2, and the third switch SW3 may have an ON failure where the switches are always on, and an OFF failure where the switches are always off. When an ON failure or an OFF failure occurs in these switches SW1 to SW3, the location of the failure can be identified to some extent based on the voltage. However, for example, it may be difficult to determine which of the second switch SW2 and the third switch SW3 used in parallel connection has a failure based only on the voltage. However, the power distribution device 60 according to this embodiment can determine which of the second switch SW2 and the third switch SW3 has a failure by further measuring the current of one of the fourth line L4 and the fifth line L5.

[0032] A detailed description will be given below of the failure determination method of the failure determination unit 63d. Figures 4 and 5 are diagrams showing the failure determination method by the failure determination unit 63d shown in Figure 1, and Figures 6 to 13 are state diagrams showing the current flow in each failure state.

[0033] First, as shown in FIG. 4, when neither charging from the quick charger 30 nor discharging to the high voltage load 50 is performed, the SW control unit 63b turns off all of the switches SW1 to SW3 as shown in FIG. 1. Therefore, the voltage measurement unit 63c should measure a voltage of 0V. Therefore, when the voltage measurement unit 63c measures 0V, the failure determination unit 63d can determine that the first switch SW1, the second switch SW2, and the third switch SW3 are all off and normal (see FIGS. 1 and 4). Also, when the sum of the voltages of the first battery 11 and the second battery 12 is detected (for example, when 800V is measured), the failure determination unit 63d can determine that the first switch SW1 has an ON failure (see FIGS. 4 and 6). However, when the voltages of the first battery 11 and the second battery 12 are the same, for example, when either one of the voltages is detected (for example, when 400V is measured), the failure determination unit 63d cannot identify the failure location. That is, in this case, the failure determination unit 63d can only determine that at least one of the second switch SW2 and the third switch SW3 has an ON failure.

[0034] Therefore, the failure determination unit 63d identifies the failure location based on the current measured by the current measurement unit 63a. Here, the current sensor 61 is provided so as to be able to measure the current in the fourth line L4. Therefore, as shown in FIG. 5, when the current measurement unit 63a detects a current larger than normal (current in parallel connection), the failure determination unit 63d can determine that the second switch SW2 has an ON failure (see FIGS. 5 and 7). Furthermore, when the current measurement unit 63a does not detect a current (when the measured value is 0 A), the failure determination unit 63d can determine that the third switch SW3 has an ON failure (see FIGS. 5 and 8). Furthermore, when the current measurement unit 63a detects the same current as in normal times, the failure determination unit 63d can determine that both the second switch SW2 and the third switch SW3 have an ON failure (see FIGS. 5 and 9).

[0035] Referring again to FIG. 4, when all the switches SW1 to SW3 transition from an OFF state to a serial state, the SW control unit 63b turns on the first switch SW1 as shown in FIG. 2. The SW control unit 63b maintains the second and third switches SW2 and SW3 OFF. In this case, the voltage measurement unit 63c should measure the sum of the voltage of the first battery 11 and the voltage of the second battery 12 (e.g., 800V). Therefore, when the voltage measurement unit 63c measures the sum, the failure determination unit 63d can determine that the first switch SW1, the second switch SW2, and the third switch SW3 are normal (see FIGS. 2 and 4). In particular, the failure determination unit 63d can determine that the failure is not an OFF failure because the first switch SW1 has transitioned to ON. On the other hand, when 0V is measured by the voltage measurement unit 63c, it can be said that the first switch SW1 did not turn on even though the SW control unit 63b executed control to turn on the first switch SW1 (see FIGS. 4 and 10). Therefore, the failure determination unit 63d determines that the first switch SW1 has an OFF failure.

[0036] Also, when all the switches SW1 to SW3 move from the OFF state to the parallel state, the SW control unit 63b turns on the second switch SW2 and the third switch SW3 as shown in FIG. 3. The SW control unit 63b maintains the first switch SW1 OFF. In this case, the voltage measurement unit 63c should measure a voltage of, for example, 400V due to the ON of the second and third switches SW2 and SW3. Therefore, when the voltage measurement unit 63c measures 0V, the failure determination unit 63d can determine that both the second and third switches SW2 and SW3 are in an OFF failure (see FIG. 4 and FIG. 11). Also, when the voltage of the first battery 11 and the voltage of the second battery 12 are the same, even if 400V, which is the voltage of one of the switches, is measured, both the second and third switches SW2 and SW3 may be normal. Furthermore, there is a possibility that either one of the second and third switches SW2 and SW3 is in an OFF failure.

[0037] Therefore, the failure determination unit 63d identifies the failure location based on the current measured by the current measurement unit 63a. Here, the current sensor 61 is provided so as to be able to measure the current in the fourth line L4. Therefore, as shown in FIG. 5, when the current measurement unit 63a detects a current larger than normal (current in parallel connection), the failure determination unit 63d can determine that the third switch SW3 has an OFF failure (see FIGS. 5 and 12). Furthermore, when the current measurement unit 63a does not detect a current (when the measured value is 0 A), the failure determination unit 63d can determine that the second switch SW2 has an OFF failure (see FIGS. 5 and 13). Furthermore, when the current measurement unit 63a detects the same current as in normal times, the failure determination unit 63d can determine that both the second switch SW2 and the third switch SW3 are normal (see FIGS. 3 and 5).

[0038] In this embodiment, the current sensor 61 is provided so as to be able to measure a current in a common portion L34 of the fourth line L4 with the third line L3. For this reason, the failure determination unit 63d may determine whether or not a current is measured by the current measurement unit 63a in order to improve the accuracy of determining an ON failure when, for example, an ON failure of the first switch SW1 shown in FIG.

[0039] In this way, according to the power distribution device 60 of the present embodiment, the voltages of the first line L1 and the second line L2 and the current in the fourth line L4 are measured to determine the failure of the first switch SW1, the second switch SW2, and the third switch SW3. Here, the first switch SW1, the second switch SW2, and the third switch SW3 may have an ON failure in which the switch is always on, and an OFF failure in which the switch is always off. When an ON failure or an OFF failure occurs in these switches SW1 to SW3, the location of the failure can be identified to some extent based on the voltage. However, it may be difficult to determine which of the switches SW2 and SW3, which are used in particular for parallel connection, has failed based only on the voltage. Therefore, the control unit 63 can determine which of the second switch SW2 and the third switch SW3 has failed by further measuring the current in the fourth line L4. Therefore, when a plurality of switches SW1 to SW3 are provided to switch between series connection and parallel connection for the batteries 11 and 12, it is possible to provide a power distribution device 60 that can identify the failed switches SW1 to SW3 and improve reliability.

[0040] In addition, since the current measurement unit 63a measures the current in the common portion L34 of the fourth line L4 with the third line L3, it is also possible to measure the current in the third line L3, thereby improving the accuracy of fault determination.

[0041] The present invention has been described above based on an embodiment, but the present invention is not limited to the above embodiment, and modifications may be made without departing from the spirit of the present invention, and if possible, known or well-known technologies may be combined.

[0042] FIG. 14 is a configuration diagram showing a secondary battery system 1 showing a first modified example according to the present embodiment. As shown in FIG. 14, the current sensor 61 may be provided in the fifth line L5, and the current measurement unit 63a may measure the current in the fifth line L5. In this case, the failure determination unit 63d determines a failure by reversing "current detection (higher than normal)" and "no current" shown in FIG. 5. For example, it is assumed that all the switches SW1 to SW3 are off, and the failure determination result based on the voltage value is an OFF failure of the second switch SW2 or the third switch SW3. In this case, when a current higher than normal is detected by the current measurement unit 63a, the failure determination unit 63d determines that an ON failure of the third switch SW3 has occurred. On the other hand, when no current is detected by the current measurement unit 63a, the failure determination unit 63d determines that an ON failure of the second switch SW2 has occurred. The same applies to the case where the first switch SW1 is off, and the second switch SW2 and the third switch SW3 are on.

[0043] In this case, it is preferable that the current sensor 61 is provided in a common portion L35 of the fifth line L5 with the third line L3, and the current measurement unit 63a measures the current in the common portion L35. This is because, in this case, the current measurement in the third line L3 can also be performed, and the accuracy of the fault determination can be improved.

[0044] FIG. 15 is a configuration diagram showing a secondary battery system 1 showing a second modified example according to the present embodiment. As shown in FIG. 15, the current sensor 61 may be provided in both the fourth line L4 (particularly the common part L34) and the fifth line L5 (particularly the common part L35). In this case, the control unit 63 further includes a second current measurement unit (second current measurement means) 63e. In this case, the current measurement unit 63a measures the current in one of the fourth line L4 and the fifth line L5, and the second current measurement unit 63e measures the current in the other of the fourth line L4 and the fifth line L5. The failure determination unit 63d determines the failure of the first switch SW1, the second switch SW2, and the third switch SW3 based on the current measured by the second current measurement unit 63e in addition to the measurement results of the voltage measurement unit 63c and the current measurement unit 63a. According to the second modification, of the second switch SW2 and the third switch SW3, one that does not conduct electricity when turned on can be determined to have an OFF failure, and one that conducts electricity when turned off can be determined to have an ON failure. [Explanation of symbols]

[0045] 1: Secondary battery system 11: First battery 12: Second battery 30: Rapid charger (charger) 50: High pressure load 60: Power distribution equipment 60a: First battery positive terminal 60b: First battery negative terminal 60c: Second battery positive terminal 60d: Second battery negative terminal 60e: Charger positive terminal 60f: Charger negative terminal 60g: Load positive terminal 60h: Load negative terminal 61: Current sensor 62: Voltage sensor 63: Control unit (control means) 63a: Current measurement unit (current measurement means) 63b: SW control section 63c: Voltage measurement unit (voltage measurement means) 63d: Failure determination unit (failure determination means) 63e: second current measuring unit (second current measuring means) L1: First line L2: Second line L3: Third line L34:Common part L35:Common part L4: 4th line L5: 5th line L6: 6th line L7: 7th line P3: Connection point P5: Connection point SW1: First switch SW2: Second switch SW3: Third switch

Claims

1. a first battery positive terminal and a first battery negative terminal connected to the positive and negative electrodes of the first battery, respectively; a second battery positive terminal and a second battery negative terminal connected to the positive and negative electrodes of the second battery, respectively; a charger positive terminal and a charger negative terminal connected to the positive and negative electrodes of the charger, respectively; a first line connecting the first battery positive terminal and the charger positive terminal; a second line connecting the second battery negative terminal and the charger negative terminal; a third line connecting the second battery positive terminal and the first battery negative terminal; a first switch that controls conduction and interruption in the third line; a fourth line connecting the second battery positive terminal and the first line; a second switch that controls the connection and disconnection of the fourth line; a fifth line connecting the second line and the first battery negative terminal; a third switch that controls the conduction and interruption of the fifth line; a control unit for controlling a conductive state and a cut-off state of the first switch, the second switch, and the third switch, The control means a voltage measuring means for measuring a voltage between the first line and the second line; a current measuring means for measuring a current in one of the fourth line and the fifth line; and a fault determination means for determining faults in the first switch, the second switch, and the third switch based on the voltage measured by the voltage measurement means and the current measured by the current measurement means. A power distribution device comprising:

2. the control means further includes a second current measuring means for measuring a current in the other of the fourth line and the fifth line, The failure determination means further determines failures in the first switch, the second switch, and the third switch based on the current measured by the second current measurement means. The power distribution device according to claim 1 .

3. The fourth line has one end shared with the third line and connected to the second battery positive terminal, The current measuring means measures a current in the fourth line and in a portion shared with the third line. The power distribution device according to claim 1 .

4. The fifth line has one end shared with the third line and connected to the negative terminal side of the first battery, The current measuring means measures a current in the fifth line and measures a current in a portion shared with the third line. The power distribution device according to claim 1 .

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