Electrical storage system

Abstract

Electrical storage system with: an electrical storage device (10); a load (20); a line (PL) configured to connect the electrical storage device (10) and the load (20); a relay (SMR-G) that is provided in the line (PL); a capacitor (C11) which has one end connected to the electrical storage device (10) and the other end connected to a ground; a voltage sensor (21) configured to detect a voltage value of the capacitor (C11); a first insulation resistance (RB) which is set up between the electrical storage device (10) and the ground; a second insulation resistor (RL) which is installed between the load (20) and the ground; a first current path (L1) which includes the first insulation resistance (RB); a second current path (L2) comprising the conductor (PL) and the second insulation resistance (RL); and a control unit (50) that is configured to (a) Controlling ON and OFF of the relay (SMR-G), and (b) Determine that the relay (SMR-G) is blocked in an ON state if the voltage value is substantially equal to a second voltage value in a case where control to turn off the relay (SMR-G) is carried out, where a first resistance value is higher than a second resistance value, the second voltage value is higher than a first voltage value, the first resistance value is a resistance value of the first insulation resistance (RB), the second resistance value is a resistance value of the second insulation resistance (RL), the first voltage value is a voltage value when a discharge current of the electrical storage device (10) flows to the capacitor (C11) in the first current path (L1), the second voltage value is a voltage value when the discharge current of the electrical storage device (10) flows to the capacitor (C11) in the second current path (L2).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to an electrical storage system or power storage system that is capable of determining whether a relay for connecting an electrical storage device or power storage device to a load is blocked in an ON state or not. 2. Description of the related technology

[0002] In Japanese patent application disclosure no. 08-226950 (JP H08-226 950 A), a capacitor is connected to main circuit wiring connected to a power supply, and an insulation resistance between the main circuit wiring and a ground (GND) potential is calculated based on the capacitor's voltage rating. One end of the capacitor is connected to the main circuit wiring on its positive side, and the other end of the capacitor is grounded.

[0003] When the insulation resistance between the main circuit wiring on one side and the ground potential is reduced, a discharge current from the power supply flows in this order to the main circuit wiring on the positive side, the capacitor, the ground potential, and the main circuit wiring on the negative side, thereby charging the capacitor. Accordingly, it is possible to determine the insulation state between the main circuit wiring on the negative side and the ground potential by detecting the voltage across the capacitor. Patent JP 2012-202723A describes a power supply device for driving a motor to power an electric vehicle, and a power supply device for charging a solar battery and supplying current to a load.US Patent 2012 / 0262183A1 describes an insulation condition detection unit designed for fault detection in switches that connect a flying capacitor to a sample-and-hold circuit for detecting a charging voltage and a ground potential, using a fault-determining threshold dependent on a variable quantity. US Patent 2014 / 0021961A1 describes a leakage current detection device that detects electrical leakage currents in a battery using a voltage divider, leakage current measurement, and dark current suppression.Patent US 2015 / 0054516A1 describes a relay welding diagnostic device that establishes a threshold based on resistance values, measures the peak value of a voltage provided by an AC signal output circuit, and assesses the condition of relays by comparing the peak value and the threshold value to diagnose whether the relays are welded. SUMMARY OF THE INVENTION

[0004] The JP-08-226950 A only determines the insulation status of the main circuit wiring (e.g., leakage or stray / creep losses in the power supply). As described in the JP-08-226950 A, a relay is used to connect the power supply to the load (in the JP-08-226950 A, a charging circuit and a motor) and to disconnect the power supply from the load. The relay consists of a movable contact and a fixed contact. If the movable contact is stuck against the fixed contact, there are cases in which the relay will remain ON. To control this, it is necessary to determine whether the relay is stuck or not.

[0005] According to one aspect of the invention, an electrical storage system comprises an electrical storage device, a load, a line, a relay, a capacitor, a voltage sensor, a first insulation resistor, a second insulation resistor, a first current path, a second current path, and a control unit. The line is configured to connect the electrical storage device and the load. The relay is provided in the line. The capacitor has one end connected to the electrical storage device and the other end connected to ground (GND). The voltage sensor is configured to detect a voltage value across the capacitor. The first insulation resistor is connected between the electrical storage device and GND. The second insulation resistor is connected between the load and GND. The first current path includes the first insulation resistor. The second current path includes the line and the second insulation resistor.

[0006] The control unit is configured to control the ON and OFF states of the relay. The control unit is configured to determine that the relay is locked in an ON state when the capacitor voltage value is substantially equal to a second voltage value in a case where control to switch the relay OFF is performed. Here, the first resistance value is higher than the second resistance value, and the second voltage value is higher than the first voltage value. The first resistance value is the resistance value of the first insulation resistance. The second resistance value is the resistance value of the second insulation resistance. The first voltage value is the voltage value when a discharge current from the electrical storage device flows to the capacitor in the first current path. The second voltage value is the voltage value when the discharge current from the electrical storage device flows to the capacitor in the second current path.

[0007] According to the aforementioned aspect, it is determined whether the relay is blocked in the ON state by paying attention to the magnitude ratio between the resistance values ​​of the first insulation resistance and the second insulation resistance.

[0008] If the resistance value of the first insulation resistor is higher than the resistance value of the second insulation resistor, the first and second voltage values ​​will have the aforementioned ratio. If the relay is blocked in the ON state despite being controlled to OFF, the discharge current of the electrical storage device will flow in the second current path, charging the capacitor. In this case, the voltage value detected by the voltage sensor is essentially equal to the second voltage value, and it can therefore be determined that the relay is blocked in the ON state.

[0009] The capacitor's voltage value is essentially equal to the first voltage value when the relay is OFF, and the capacitor's voltage value is essentially equal to the second voltage value when the relay is ON. Since the first and second voltage values ​​have the aforementioned magnitude ratio, it is possible to determine whether the relay is blocked in the ON state, while distinguishing between the OFF and ON states.

[0010] According to another aspect of the invention, an electrical storage system comprises an electrical storage device, a load, a line, a relay, a capacitor, a voltage sensor, a first insulation resistor, a second insulation resistor, a first current path, a second current path, and a control unit. The line is configured to connect the electrical storage device and the load. The relay is provided in the line. The capacitor has one end connected to the electrical storage device and the other end connected to ground (GND). The voltage sensor is configured to detect a voltage value across the capacitor. The first insulation resistor is connected between the electrical storage device and GND. The second insulation resistor is connected between the load and GND. The first current path includes the first insulation resistor.The second current path includes the conductor and the second insulation resistance. The control unit is configured to control the ON and OFF positions of the relay, and to determine that the relay is locked in an ON state when the voltage difference, in a case where control to switch the relay between ON and OFF is performed, is less than the difference between a first voltage value and a second voltage value.

[0011] Here, the first resistance value is higher than the second resistance value, and the first voltage value is lower than the second voltage value. The first resistance value is the resistance value of the first insulation resistance. The second resistance value is the resistance value of the second insulation resistance. The first voltage value is the voltage value when a discharge current from the electrical storage device flows to the capacitor in the first current path. The second voltage value is the voltage value when the discharge current from the electrical storage device flows to the capacitor in the second current path. The voltage difference is the voltage difference between the capacitor voltage detected by the voltage sensor when a control signal is executed to switch the relay ON, and the capacitor voltage detected by the voltage sensor when a control signal is executed to switch the relay OFF.

[0012] If the relay is stuck in the ON state, the voltage values ​​detected by the voltage sensor are essentially the same, even when the control signal to switch the relay ON or OFF is applied. The voltage difference at this point is smaller than the difference between the first and second voltage values. Therefore, it can be determined that the relay is stuck in the ON state if the voltage difference is smaller than the difference between the first and second voltage values.

[0013] Additionally, by calculating the voltage difference, it is possible to determine whether the relay is locked in the ON state, even when changes in the capacitor's capacitance are not considered or verified. If changes in the capacitor's capacitance occur, the voltage value detected by the voltage sensor will be shifted relative to either the first or second voltage value. In this case, it becomes difficult to determine whether the capacitor's voltage value is essentially equal to the second voltage value, and consequently, whether the relay is locked in the ON state.

[0014] When changes in the capacitor's capacitance occur, the voltage across the capacitor shifts relative to either the first or second voltage value in the same direction (towards the higher or lower end of the voltage value). Accordingly, the voltage difference at this point corresponds to the difference between the first and second voltage values ​​when the relay is not locked in the ON state. Conversely, the voltage difference at this point is smaller than the difference between the first and second voltage values ​​when the relay is locked in the ON state. Therefore, even when changes in the capacitor's capacitance are not being considered or verified, it is possible to determine whether the relay is locked in the ON state by observing the voltage difference.

[0015] In the aforementioned aspect, the capacitor can comprise a first capacitor and a second capacitor. The second capacitor is connected in parallel to the first capacitor. The capacitance of the second capacitor is smaller than the capacitance of the first capacitor. A first switching element can be connected in series with the first capacitor. A second switching element can be connected in series with the second capacitor and in parallel with the first capacitor and the first switching element.

[0016] The control unit can be configured to switch the first switching element ON and the second switching element OFF when it detects a leakage or stray / creep loss resulting from a decrease in the first resistance value. The control unit can also be configured to determine that the leakage or stray / creep loss resulting from the decrease in the first resistance value has occurred when the voltage value detected by the voltage sensor is higher than or equal to a third voltage value.

[0017] The third voltage value is higher than the second voltage value. Additionally, the control unit can be configured to switch the first switching element OFF and the second switching element ON when the control unit determines that the relay is blocked.

[0018] This means that the first capacitor is charged with the discharge current of the electrical storage device when the occurrence of leakage or stray / creep loss is determined, and the second capacitor is charged with the discharge current of the electrical storage device when the relay is blocked. Thus, by appropriately using the first or second capacitor, as the situation requires, it is possible to determine the occurrence of leakage or stray / creep loss, and it becomes easier to determine whether the relay is blocked in the ON state or not.

[0019] If the resistance of the first insulation resistor is reduced, the current in the first current path increases. Therefore, it is preferable to use a capacitor with a larger capacitance than the second capacitor. This allows you to determine whether a leak has occurred based on whether the voltage across the first capacitor is less than or equal to the third voltage. Since both the first and second voltages are lower than the third, it becomes difficult to distinguish between them using only the first capacitor. To overcome this, it is easier to differentiate between the first and second voltages by using a second capacitor with a smaller capacitance than the first.This makes it easier to determine, based on the voltage value of the second capacitor, whether the relay is blocked in the ON state or not.

[0020] Regarding the aforementioned aspect, the control unit can be configured to determine that the first switching element is faulty in an OFF state when a control action is performed to switch the first switching element ON and a control action is performed to switch the second switching element OFF, and when the voltage value detected by the voltage sensor is essentially 0; and to determine that the second switching element is faulty in an ON state when the voltage value detected by the voltage sensor is lower than a fourth voltage value. The fourth voltage value is the voltage value when the discharge current of the electrical storage device flows to the first capacitor in either the first current path or the second current path.Therefore, if the control to switch the first switching element ON and the control to switch the second switching element OFF is carried out, it is possible to determine, based on the voltage value detected by the voltage sensor, whether the first switching element or the second switching element is faulty or not.

[0021] Specifically, the control unit determines that the first switching element is faulty in the OFF state when the voltage value detected by the voltage sensor is essentially zero (0 [V]). When the first switching element is controlled to ON and operates according to this control, the first capacitor is charged by the discharge current of the electrical storage device. If the voltage value detected by the voltage sensor (the voltage value of the first capacitor) is essentially zero (0 [V]), the first capacitor is not charged. Therefore, it can be determined that the first switching element is faulty in the OFF state.

[0022] Additionally, the control unit determines that the second switching element is faulty in the ON state if the voltage value detected by the voltage sensor is lower than the voltage value when the discharge current of the electrical storage device flows to the first capacitor in either the first or second current path. If the second switching element is controlled to OFF and operates according to this control as described above, only the first capacitor will be charged by the discharge current of the electrical storage device. If the voltage value detected by the voltage sensor is lower than the voltage value when only the first capacitor is charged, it can be determined that the second capacitor is also being charged. This indicates that the second switching element is faulty in the ON state.

[0023] Regarding the aforementioned aspect, the control unit can be configured to determine that the second switching element is faulty in the OFF state when a control action is performed to switch the first switching element OFF and a control action is performed to switch the second switching element ON, and when the voltage value detected by the voltage sensor is essentially 0; and to determine that the first switching element is faulty in the ON state when the voltage value detected by the voltage sensor is lower than a fifth voltage value. The fifth voltage value is the voltage value when the discharge current of the electrical storage device flows to the second capacitor in either the first current path or the second current path.When the control is performed to switch the first switching element OFF and the control is performed to switch the second switching element ON, it is possible, similar to the case described above, to determine whether the first or the second switching element is faulty or not, based on the voltage value detected by the voltage sensor. Specifically, the control unit determines that the second switching element is faulty in the OFF state if the voltage value detected by the voltage sensor is essentially 0 [V]. Additionally, the control unit determines that the first switching element is faulty in the ON state if the voltage value detected by the voltage sensor is lower than the voltage value when the discharge current of the electrical storage device flows to the second capacitor in either the first or second current path. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and for which the following applies: Fig. 1 is a representation showing a configuration of a battery system; Fig. Figure 2 is a diagram showing a configuration of a circuit that controls the system's main relays; Fig. Figure 3 is a representation to illustrate a path along which a discharge current from a battery pack flows to a first leak detection circuit in a first embodiment; Fig. Figure 4 is a representation to illustrate a path along which the discharge current of the battery pack flows to a second leak detection circuit in the first embodiment; Fig. Figure 5 is a flowchart showing a process for determining a battery pack leak and a system main relay blockage in the first embodiment; Fig. Figure 6 is a representation showing a relationship between a voltage value of the battery pack and a voltage value of a capacitor; Fig. 7 is a diagram to illustrate the path along which the discharge current of the battery pack flows to the first leak detection circuit in a second embodiment; Fig. Figure 8 is a diagram illustrating the path along which the discharge current of the battery pack flows to the second leak detection circuit in the second embodiment; Fig. Figure 9 is a flowchart showing a process for determining battery pack leakage in the second embodiment; Fig. 10 is a flowchart showing a process for determining the blocking of the system main relay in the second embodiment; Fig. Figure 11 is a flowchart showing a process for determining a fault of a switching element included in the first leak detection circuit in a third embodiment; Fig. Figure 12 is a representation to illustrate that the correspondence between the voltage value of the battery pack and the voltage value of the capacitor is shifted due to a change in the capacitance of the capacitor; and Fig. Figure 13 is a flowchart showing a process for determining the blocking of the system main relay in a fourth embodiment. DETAILED DESCRIPTION OF EXAMPLES OF EXECUTION

[0025] Exemplary embodiments of the invention are described below.

[0026] A battery system of the exemplary embodiment (which corresponds to an electrical storage system or an energy storage system of the invention) is operated by using Fig. 1 described. A battery pack or set 10 (corresponding to an electrical storage device or an energy storage device of the invention) has a plurality (any number) of individual cells 11 connected in series. It is possible to use a secondary battery or accumulator, such as a nickel-metal hydride battery or a lithium-ion battery, as the individual cell 11. It is also possible to use an electrical double-layer capacitor instead of the secondary battery or accumulator. It should be noted that a plurality of the individual cells 11 connected in parallel can be included in the battery pack or set 10.

[0027] The battery pack 10 is configured in a state where it is isolated from GND. A resistive element RB defines an insulation resistance (corresponding to a first insulation resistance of the invention) between the battery pack 10 and GND. For example, when the battery pack 10 is installed on a vehicle, the vehicle body to which the battery pack 10 is attached serves as GND.

[0028] A positive electrode lead PL is connected to a positive electrode terminal of the battery pack 10, and a negative electrode lead NL is connected to a negative electrode terminal of the battery pack 10. The battery pack 10 is connected to a load 20 via the positive electrode lead PL and the negative electrode lead NL. The load 20 is configured in a state where it is isolated from GND. A resistive element RL defines an insulation resistance (corresponding to a second insulation resistance of the invention) between the load 20 and GND. For example, if the load 20 is installed on the vehicle, the vehicle body to which the load 20 is attached serves as GND.

[0029] The resistance value of resistor RB is higher than the resistance value of resistor RL. For example, the resistance values ​​of resistors RB and RL differ in the number of decimal places. The load 20 includes an electronic component connected to GND, and therefore the resistance value of resistor RL tends to be low. On the other hand, the battery pack 10 serves as a high-voltage power supply, and therefore it is necessary to ensure isolation between the battery pack 10 and GND, and therefore the resistance value of resistor RB tends to be high. Consequently, the resistance value of resistor RB is higher than the resistance value of resistor RL. In the embodiment described below, a reduction in the resistance value of resistor RB is considered.On the other hand, the resistance value of the resistance element RL is considered a fixed value.

[0030] When the battery pack 10 is installed on the vehicle, a motor generator is connected to the battery pack 10. Additionally, there are cases where an inverter and a boost converter are provided in a current path between the battery pack 10 and the motor generator. In these cases, the load 20 includes the motor generator, the inverter, and the boost converter. On the other hand, some vehicles with battery packs 10 installed can charge the battery packs 10 using electrical energy from an external power supply. In this case, a charging device is installed on the vehicle, and the load 20 also includes the charging device. The charging device converts the AC energy / power supplied by the external power supply into DC energy.DC energy / power and delivers the DC current or DC voltage energy / power to the battery pack 10.

[0031] A system main relay SMR-B, provided in the positive electrode line PL, receives a control signal from a control unit 50 and switches between ON and OFF. A system main relay SMR-G, provided in the negative electrode line NL, also receives the control signal from the control unit 50 and switches between ON and OFF. A voltage sensor 21 detects a voltage value Vb of the battery pack 10 and outputs the detection result to the control unit 50. The control unit 50 has a memory 51, and information for the execution of the predetermined processes by the control unit 50 is stored in the memory 51.

[0032] One end of a first leak detection circuit 30 is connected to GND, and the other end is connected via a detection line DL1 to the negative electrode line NL. The first leak detection circuit 30 is used to determine whether a decrease in the insulation resistance (the resistance value of the resistive element RB) of the battery pack 10, i.e., a leak or stray / creep loss of the battery pack 10, has occurred. Additionally, the first leak detection circuit 30 is used to determine whether the system main relay SMR-B is blocked in an ON state.

[0033] One end of a second leak detection circuit 40 is connected to GND, and the other end is connected via a detection line DL2 to the positive electrode line PL. The second leak detection circuit 40 is used to determine whether a decrease in the insulation resistance (the resistance value of the resistive element RB) of the battery pack 10, i.e., whether or not leakage or stray / creep loss of the battery pack 10 has occurred. Additionally, the second leak detection circuit 40 is used to determine whether the system main relay SMR-G is blocked in the ON state. Hereinafter, the blocking of the system main relay SMR-B or the system main relay SMR-G in the ON state is simply referred to as "blocking." The specific configuration of each of the first leak detection circuit 30 and the second leak detection circuit 40 is described below.

[0034] Next, a circuit for controlling the system's main relays SMR-B and SMR-G will be described using... Fig. 2 described.

[0035] Each of the system main relays SMR-B and SMR-G has a movable contact MC and a fixed contact FC. When each of the system main relays SMR-B and SMR-G is OFF, the movable contact MC receives a bias force from a biasing element (not shown) and is spaced apart from the fixed contact FC. When the control unit 50 switches a switching element 61 from OFF to ON, a current flows from a power supply 62 to a coil 63, thereby generating an electromagnetic force in the coil 63. The electromagnetic force causes the movable contact to come into contact with the fixed contact FC against the bias force of the biasing element described above. This switches each of the system main relays SMR-B and SMR-G to ON. If the battery pack 10 is installed on the vehicle, it is possible to use an auxiliary or additional battery installed on the vehicle as the power supply 62.Additionally, it is also possible to use the battery pack 10 as the energy source 62.

[0036] In the Fig. In the configuration shown in Figure 2, it is possible to cause the movable contacts MC of the dual-system main relays SMR-B and SMR-G to operate simultaneously by switching between excitation and de-excitation of coil 63. It should be noted that it is possible to provide the switching element 61 and the coil 63 in each of the dual-system main relays SMR-B and SMR-G. In this case, it is possible to cause the movable contacts MC of the dual-system main relays SMR-G and SMR-G to operate individually by switching between excitation and de-excitation of each coil 63.

[0037] Next, the configuration of the first leak detection circuit 30 will be carried out using Fig. 3 described.

[0038] One end of the first leak detection circuit 30 is connected to GND, and the other end is connected via the detection line DL1 and the negative electrode line NL to the negative electrode terminal of the battery pack 10. A cathode of diode D1 is connected via the detection line DL1 and the negative electrode line NL to the negative electrode terminal of the battery pack 10. An anode of diode D1 is connected to one end of switching element SW10. One end of capacitor C11 is connected to the other end of switching element SW10, and the other end of capacitor C11 is connected to GND.

[0039] A switching element SWR1 and a resistor R1 are electrically connected in parallel to capacitor C11. Switching element SWR1 and resistor R1 are connected in series. Each of the switching elements SW10 and SWR1 receives the control signal from the control unit 50 and is switched between ON and OFF. A voltage sensor 31 detects a voltage value Vc across capacitor C11 and outputs the detection result to the control unit 50.

[0040] When determining whether or not the battery pack 10 has leaked, a current path L1 (corresponding to a first current path of the invention) is used, which is located in Fig. 3 is indicated by a dashed line. If the battery pack 10 has leaked, the resistance of the resistor element RB decreases. When the switching element SW10 is switched ON, the discharge current of the battery pack 10 flows in the current path L1, and charge accumulates in the capacitor C11. This makes it more likely that the voltage value Vc of the capacitor C11 will increase.

[0041] On the other hand, if the battery pack 10 is not leaking, even if the switching element SW10 is switched ON, it is less likely that the discharge current of the battery pack 10 will flow in the current path L1, and it is less likely that the charge will accumulate in the capacitor C11. Therefore, it is less likely that the voltage value Vc of the capacitor C11 will increase. As described above, the voltage value Vc of the capacitor C11 differs depending on whether the battery pack 10 is leaking or not. Consequently, it is possible to determine whether the battery pack 10 is leaking or not by detecting the voltage value Vc of the capacitor C11.

[0042] When determining whether the system main relay SMR-B is blocked or not, a current path L2 (corresponding to a second current path of the invention) is used, which is in Fig. 3 is indicated by a dashed line. If there is no leakage from battery pack 10 and the system main relay SMR-B is blocked, the discharge current from battery pack 10 flows in current path L2 when switching element SW10 is switched ON. Since the resistance value of resistor element RL is lower than the resistance value of resistor element RB, the discharge current from battery pack 10 flows in current path L2. As the current flows in current path L2, charge accumulates in capacitor C11, and the voltage value Vc of capacitor C11 increases.

[0043] If the system main relay SMR-B is not blocked and is OFF, even if the switching element SW10 is ON, the discharge current of battery pack 10 is less likely to flow in current path L2. This means that the discharge current of battery pack 10 flows in current path L1 when the system main relay SMR-B is OFF. In this case, as described above, it is less likely that charge will accumulate in capacitor C11, and the voltage value Vc of capacitor C11 will be less likely to increase.

[0044] As described above, the voltage value Vc of capacitor C11 differs depending on whether the system main relay SMR-B is blocked or not. Therefore, by detecting the voltage value Vc of capacitor C11, it is possible to determine whether the system main relay SMR-B is blocked or not.

[0045] It is possible to define the resistance value of the resistive element RB, when it is determined that the leakage of battery pack 10 has occurred, as a threshold value R. RB _th is preset. Normally, the threshold is R. RB _th is set to a value lower than the resistance value of the resistive element RL. Therefore, the current value is [value missing] when the resistance value of the resistive element RB equals the threshold value R. RB _th becomes and the current in the current path L1 flows, greater than the current value when the system main relay SMR-B is blocked and the current in the current path L2 flows.

[0046] Therefore, the voltage value Vc of capacitor C11 is higher when it is determined that battery pack 10 has leaked than the voltage value Vc of capacitor C11 when the system main relay SMR-B is blocked. This makes it possible to distinguish between the case where battery pack 10 has leaked and the case where the system main relay SMR-B is blocked, based on the voltage value Vc of capacitor C11.

[0047] By switching off switching element SW10 and switching on switching element SWR1 after the charge has accumulated in capacitor C11, it is possible to discharge capacitor C11 via resistor element R1. In a state where the voltage value Vc of capacitor C11 is 0 [V], it is then possible to repeat the determination of whether or not battery pack 10 has leaked and whether or not the system main relay SMR-B is blocked.

[0048] Next, the configuration of the second leak detection circuit 40 will be carried out using Fig. 4 described.

[0049] One end of the second leak detection circuit 40 is connected to GND, and the other end is connected via the detection line DL2 and the positive electrode line PL to the positive electrode terminal of the battery pack 10. The anode of diode D2 is connected via the detection line DL2 and the positive electrode line PL to the positive electrode terminal of the battery pack 10. The cathode of diode D2 is connected to one end of switching element SW20. One end of capacitor C21 is connected to the other end of switching element SW20, and the other end of capacitor C21 is connected to GND. It is possible to use a capacitor with the same capacitance as capacitor C11 or with a different capacitance than capacitor C11.

[0050] A switching element SWR2 and a resistor R2 are electrically connected in parallel to capacitor C21. Switching element SWR2 and resistor R2 are also connected in series. Each of the switching elements SW20 and SWR2 receives the control signal from control unit 50 and is switched between ON and OFF. A voltage sensor 41 detects the voltage value Vc of capacitor C21 and outputs the detection result to control unit 50.

[0051] When determining whether or not the battery pack 10 is leaking, a current path L3 (corresponding to the first current path of the invention) is used, which is located in Fig. 4 is indicated by a dashed line. When the system main relays SMR-B and SMR-G are OFF, if the switching element SW20 is ON, the discharge current of battery pack 10 flows in current path L3, and the charge is accumulated in capacitor C21. This is similar to the case where, by using Fig. As described in section 3, the voltage value Vc of capacitor C21 differs depending on whether or not the battery pack 10 has leaked. Therefore, it is possible to determine whether or not the battery pack 10 has leaked by detecting the voltage value Vc of capacitor C21.

[0052] When determining whether the system main relay SMR-G is blocked or not, a current path L4 (corresponding to the second current path of the invention) is used, which is in Fig. 4 is indicated by a dashed line. If there is no leakage from battery pack 10 and the system main relay SMR-G is blocked, the discharge current of battery pack 10 flows in current path L4 when switching element SW20 is ON, and the charge is accumulated in capacitor C21. This is similar to the case where, by using Fig. As described in section 3, the voltage value Vc of capacitor C21 differs depending on whether the system main relay SMR-G is blocked or not. Accordingly, it is possible to determine whether the system main relay SMR-G is blocked or not by detecting the voltage value Vc of capacitor C21.

[0053] On the other hand, similar to the case that arises from the use of Fig. As described in section 3, the voltage value Vc of capacitor C21, when it is determined that battery pack 10 has leaked, is higher than the voltage value Vc of capacitor C21 when the system main relay SMR-G is blocked. This makes it possible to distinguish between the case where battery pack 10 has leaked and the case where the system main relay SMR-G is blocked, based on the voltage value Vc of capacitor C21.

[0054] By switching off switching element SW20 and switching on switching element SWR2 after the charge has accumulated in capacitor C21, it is possible to discharge capacitor C21 via resistor element R2. In a state where the voltage value Vc of capacitor C21 is 0 [V], it is then possible to repeat the determination of whether or not battery pack 10 has leaked and whether or not the system main relay SMR-G is blocked.

[0055] Next, a process for determining whether battery pack 10 has leaked or system main relay SMR-B has jammed is described using a flowchart shown in Fig. 5 is shown. That in Fig. The flowchart shown in section 5 is executed by control unit 50.

[0056] It should be noted that the in Fig. The process shown in Figure 5 uses the first leak detection circuit 30, but a similar process can be performed using the second leak detection circuit 40. Therefore, the detailed description of the process using the second leak detection circuit 40 is omitted. When using the second leak detection circuit 40, it is possible to determine whether or not the battery pack 10 has leaked and whether or not the system main relay SMR-G has been blocked.

[0057] If the process, which is similar to the one in Fig. In the process shown in Figure 5, the second leak detection circuit 40 is used, switching elements SW20 and SWR2 are used instead of switching elements SW10 and SWR1, and the voltage value Vc is detected by the voltage sensor 41. Here, the voltage value Vc is set to each of the threshold values ​​Vth1 and Vth2 described below, corresponding to the capacitance of capacitor C21.

[0058] In step S101, control unit 50 outputs the control signal to switch off the system main relays SMR-B and SMR-G. It should be noted that it is only necessary to output the control signal to switch off the system main relay SMR-B if the system main relays SMR-B and SMR-G can be operated individually.

[0059] In step S102, the control unit 50 switches the switching element SW10 ON and the switching element SWR1 OFF. In step S103, the control unit 50 remains stationary or waits until a predetermined time has elapsed since the end of the process in step S102. The capacitor C11 is charged for the duration of the predetermined time with the current flowing in current path L1 or current path L2, which are located in Fig. 3 are shown.

[0060] When the predetermined time has elapsed in the process in step S103, the control unit 50 detects the voltage value Vb in step S104 using voltage sensor 21, and also detects the voltage value Vc of capacitor C11 using voltage sensor 31. In step S105, the control unit 50 determines whether the voltage value Vc detected in the process in step S104 is less than the threshold value Vth1.

[0061] The threshold value Vth1 (corresponding to a third voltage value of the invention) is a threshold value (the voltage value Vc) for determining whether or not the battery pack 10 has leaked and can be preset. Specifically, as described above, it is possible to set the threshold value Vth1 based on the threshold value R. RB to set _th when the resistance value (threshold) R RB The threshold value Vth of the resistive element RB is preset when it is determined that a leakage from battery pack 10 has occurred. The voltage value Vc of capacitor C11 depends on the voltage value Vb of battery pack 10, and therefore the threshold value Vth1 can be changed according to the voltage value Vb.

[0062] Specifically, how it is in Fig. As shown in Figure 6, it is possible to determine the threshold value Vth1, which corresponds to the voltage value Vb, by detecting the voltage value Vb, provided that a correspondence (a characteristic map or an arithmetic expression) between the threshold value (the voltage value Vc) Vth1 and the voltage value Vb has been prepared or created in advance. It should be noted that there are cases in which the voltage value Vc of capacitor C11 is less likely to change, even if the voltage value Vc changes. In these cases, it is not necessary to change the threshold value Vth1 according to the voltage value Vb, and it is possible to set a fixed value as the threshold value Vth1.

[0063] If the voltage value Vc is not less than the threshold value Vth1, the control unit 50 determines in step S106 that a leakage of the battery pack 10 has occurred. If a leakage of the battery pack 10 has occurred, the resistance value of the resistor element RB is normally equal to the threshold value R described above. RB _th. Therefore, it can be determined that the leakage of battery pack 10 occurred when the voltage value Vc corresponds to the threshold value Vth1.

[0064] Taking into account a detection error of the voltage sensor 31, it can be determined that the leakage of the battery pack 10 has occurred if the voltage value Vc falls within the detection error range, which uses the threshold value Vth1 as a reference value. The detection error range, which uses the threshold value Vth1 as a reference value, defines a range between a value (upper limit) obtained by adding a predetermined detection error to the threshold value Vth1 and a value (lower limit) obtained by subtracting the predetermined detection error from the threshold value Vth1.

[0065] On the other hand, depending on the leakage or stray / creep (loss) condition of the battery pack, there are 10 cases in which the resistance value of the resistance element RB becomes lower than the threshold value R described above. RBIn these cases, the stress value Vc is higher than the threshold value Vth1. Considering this, step S105 of the process determines whether the stress value Vc is lower than the threshold value Vth1 or not.

[0066] In the process in step S106, the control unit 50 can, for example, set a flag regarding the occurrence of leakage (leakage flag). On the other hand, in the process in step S105, the control unit 50 determines that the battery pack 10 is not leaking if the voltage value Vc is lower than the threshold value Vth1.

[0067] Subsequently, in step S107, the control unit 50 determines whether the voltage value Vc detected in the process in step S104 is equal to the threshold value Vth2 (which corresponds to a second voltage value of the invention) or not. Considering the detection error of the voltage sensor 31, it is also possible in step S107 to determine whether the voltage value Vc falls within the range of the detection error, which uses the threshold value Vth2 as a reference value. That is, it is possible to determine whether the voltage value Vc is essentially equal to the threshold value Vth2 or not.The detection error range, which has the threshold Vth2 as a reference value, defines a range between a value (upper limit) obtained by adding a predetermined detection error to the threshold Vth2 and a value (lower limit) obtained by subtracting the predetermined detection error from the threshold Vth2.

[0068] The threshold value Vth2 is a threshold (the voltage value Vc) used to determine whether the system main relay SMR-B is blocked or not, and can be preset. If the system main relay SMR-B is blocked and ON, the discharge current of battery pack 10 flows into the Fig. The current path L2 shown in Figure 3 determines the threshold value Vth2, which is set based on the resistance value of the resistor element RL. Since the voltage value Vc of capacitor C11 depends on the voltage value Vb of battery pack 10, it is possible to change the threshold value Vth2 according to the voltage value Vb.

[0069] Specifically, how it is in Fig. As shown in Figure 6, it is possible to determine the threshold value Vth2, which corresponds to the voltage value Vb, by detecting the voltage value Vb, provided that a correspondence (a characteristic map or an arithmetic expression) between the threshold value (the voltage value Vc) Vth2 and the voltage value Vb has been created or prepared in advance. It should be noted that there are cases in which the voltage value Vc of capacitor C11 is less likely to change, even if the voltage value Vb changes. In these cases, it is not necessary to change the threshold value Vth2 according to the voltage value Vb, and it is possible to set a fixed value as the threshold value Vth2.

[0070] As described above, the resistance value of resistor element RL is higher than the resistance value of resistor element RB when it is determined that battery pack 10 has leaked. Accordingly, the voltage value Vc of capacitor C11 when the system main relay SMR-B is blocked is lower than the voltage value Vc of capacitor C11 when it is determined that battery pack 10 has leaked. Therefore, as described in Fig. As shown in Figure 6, the threshold Vth2 is lower than the threshold Vth1.

[0071] If, in step S107 of the process, the voltage value Vc equals the threshold value Vth2, the control unit 50 determines in step S108 that the system main relay SMR-B has been blocked. At this point, the control unit 50 can, for example, set a flag indicating the occurrence of the blocking (blocking flag).

[0072] If the battery pack 10 is not leaking, the system main relay SMR-B is not blocked, and the system main relay SMR-B is OFF, the voltage value Vc of the capacitor C11 denotes a voltage value Vc_n (corresponding to a first voltage value of the invention) at the time of a normal state, which in Fig. Figure 6 shows that if there is no leakage from battery pack 10 and the system main relay SMR-B is OFF, the discharge current from battery pack 10 is less likely to flow to capacitor C11, and the voltage value Vc of capacitor C11 is less likely to increase. Accordingly, as shown in Fig. As shown in Figure 6, the voltage value Vc_n at the time of normal conditions is lower than the threshold value Vth2.

[0073] If, in step S107 of the process, the voltage value Vc is equal to the voltage value Vc_n, the control unit 50 determines that the voltage value Vc and the threshold value Vth2 are different from each other. At this point, the control unit 50 determines that the system main relay SMR-B is not blocked and terminates the process. Fig. The process shown in Figure 5. Since the voltage value Vc of capacitor C11 depends on the voltage value Vb, the voltage value Vc_n changes according to the voltage value Vb during the normal state.

[0074] If the leak flag is set in step S106 of the process, it is possible, for example, to send an alarm to a user. The alarm can be triggered by sound or a visual signal. Additionally, even if the leak flag is set, control unit 50 can prevent, for example, the system's main relays SMR-B and SMR-G from being switched ON.

[0075] On the other hand, if the blocking flag is set in step S108 of the process, it is possible, for example, to send an alarm to the user. Additionally, if the system main relay SMR-G is not blocked, the control unit 50 can prevent it from being switched ON. If the system main relays SMR-B and SMR-G are blocked, the control unit 50 can prevent the charging / discharging of the battery pack 10 by preventing the operation of the load 20.

[0076] According to the exemplary embodiment, it is possible to determine, using the first leak detection circuit 30 or the second leak detection circuit 40, whether or not leakage or stray / creep loss of the battery pack 10 has occurred. Additionally, if leakage or stray / creep loss of the battery pack 10 is not present, it is possible, using the first leak detection circuit 30 or the second leak detection circuit 40, to determine whether the system main relay SMR-B or the system main relay SMR-G has been blocked, by monitoring the difference in resistance value between the resistance elements RB and RL.

[0077] As it is in Fig. As shown in Figure 2, in the configuration where a coil 63 switches between excitation and de-excitation, the movable contacts MC of the system main relays SMR-B and SMR-G operate simultaneously. By detecting the voltage supplied from the battery pack 10 to the load 20, it is possible to determine whether the system main relays SMR-B and SMR-G are blocked or not. That is, if the detected voltage value corresponds to the voltage Vb of the battery pack 10, it can be determined that both system main relays SMR-B and SMR-G are blocked.

[0078] However, in such a method it is not possible to determine whether either of the system main relays SMR-B and SMR-G is blocked or not. According to the exemplary embodiment, it is possible to determine whether the system main relay SMR-B has been blocked or not by using the first leak detection circuit 30. Additionally, it is possible to determine whether the system main relay SMR-G has been blocked or not by using the second leak detection circuit 40. Thus, it is possible to determine whether each of the system main relays SMR-B and SMR-G has been blocked or not by using the first leak detection circuit 30 and the second leak detection circuit 40.

[0079] A second embodiment of the invention is described. In this embodiment, the same components as those described in the first embodiment are designated by the same reference numerals, and their detailed description is omitted. The following section mainly describes points that differ from the first embodiment.

[0080] In the first embodiment, if the battery pack 10 leaks, the current value increases when the current in the Fig. 3 shown power line L1 or the one in Fig. Current flows along the current path L3 shown in Figure 4. This makes it more likely that the voltage values ​​Vc of capacitors C11 and C21 will increase, and therefore it is necessary to increase the capacitances of capacitors C11 and C21. In the case where the capacitances of capacitors C11 and C21 are set to large capacitances, it is possible to determine, based on the voltage values ​​Vc of capacitors C11 and C21, whether or not the battery pack 10 has leaked, while between the threshold values ​​Vth1 and Vth2, which are shown in Figure 4, the voltage values ​​Vth1 and Vth2 are determined. Fig. The 6 are shown, and a distinction is made.

[0081] However, if the capacitances of capacitors C11 and C21 are increased / have been increased, as described below, there are cases where it becomes difficult to distinguish between the threshold value Vth2 and the voltage value Vc_n at the time of normal conditions, which is in Fig. As shown in section 6, it is possible to distinguish between them.

[0082] Even if a predetermined amount of charge accumulates in each of capacitors C11 and C21, the behavior (slope rate) of the voltage value Vc across each of capacitors C11 and C21 changes according to their respective capacitances. Specifically, the slope of the voltage value Vc is smaller when the capacitance of each capacitor is larger. As shown in Fig. As shown in Figure 6, there are cases where it becomes difficult to distinguish between the threshold value Vth2 and the voltage value Vc_n, because the threshold value Vth2 and the voltage value Vc_n are lower than the threshold value Vth1 when the capacitance of each of the capacitors C11 and C21 is increased. In these cases, it becomes difficult to determine, based on the voltage value Vc, whether each of the system's main relays SMR-B and SMR-G has been blocked or not.

[0083] In light of this point, different capacitors are used in the embodiment, such that the capacitor used to determine whether or not a leak has occurred in battery pack 10 differs from the capacitor used to determine whether or not each of the system's main relays SMR-B and SMR-G has been blocked. That is to say, in the embodiment, the configuration of the first leak detection circuit 30 and the configuration of the second leak detection circuit 40 are modified compared to those in the first embodiment.

[0084] The configuration of the first leak detection circuit 30 in the exemplary embodiment is achieved by using Fig. As described in section 7, a switching element SW11 (corresponding to a first switching element of the invention) is provided between the switching element SW10 and the capacitor C11 (which corresponds to a first switching element of the invention). A switching element SW12 (corresponding to a second switching element of the invention) and a capacitor C12 (corresponding to a second capacitor of the invention) are electrically connected in parallel with the switching element SW11 and the capacitor C11. The switching element SW12 and the capacitor C12 are electrically connected in series with each other. The switching element SWR1 and the resistor R1 are electrically connected in parallel with the switching element SW11 and the capacitor C11, and are also electrically connected in parallel with the switching element SW12 and the capacitor C12.

[0085] Capacitor C11 is used to determine whether or not battery pack 10 has leaked. Capacitor C12 is used to determine whether or not the system's main relay, SMR-B, has jammed. The capacitance of capacitor C12 is smaller than the capacitance of capacitor C11.

[0086] The configuration of the second leak detection circuit 40 in the exemplary embodiment is achieved by using Fig. As described in section 8. A switching element SW21 (corresponding to the first switching element of the invention) is provided between the switching element SW20 and the capacitor C21 (which corresponds to the first capacitor of the invention). A switching element SW22 (corresponding to the second switching element of the invention) and a capacitor C22 (corresponding to the second capacitor of the invention) are electrically connected in parallel with the switching element SW21 and the capacitor C21. The switching element SW22 and the capacitor C22 are electrically connected in series with each other. The switching element SWR2 and the resistor R2 are electrically connected in parallel with the switching element SW21 and the capacitor C21 and are also electrically connected in parallel with the switching element SW22 and the capacitor C22.

[0087] Capacitor C21 (corresponding to the first capacitor of the invention) is used to determine whether or not battery pack 10 has leaked. Capacitor C22 (corresponding to the second capacitor of the invention) is used to determine whether or not the system main relay SMR-G has jammed. The capacitance of capacitor C22 is smaller than the capacitance of capacitor C21.

[0088] Next, a process for determining whether or not battery pack 10 has leaked will be described, using the methods described in Fig. The first leak detection circuit 30 shown in Figure 7 is described using a flowchart that is shown in Figure 7. Fig. 9 is shown. The one in Fig. The process shown in Figure 9 is executed by control unit 50.

[0089] It should be noted that the in Fig. The process shown in 9 is the process that is in Fig. The first leak detection circuit 30 shown in section 7 is used, but a similar process can also be carried out by using the circuit shown in section 30. Fig. The second leak detection circuit 40 shown in Figure 8 is used. Therefore, the detailed description of the process using the second leak detection circuit 40 is omitted. If the process is similar to the one shown in Figure 8, the following applies: Fig. In the process shown in Figure 9, which is carried out using the second leak detection circuit 40, the switching elements SW20, SW21, SW22, and SWR2 are used instead of the switching elements SW10, SW11, SW12, and SWR1. Additionally, the voltage value Vc is detected by the voltage sensor 41. Furthermore, the voltage value Vc, which corresponds to the capacitance of capacitor C21, is set as the threshold value Vth1, as described below.

[0090] In step S201, control unit 50 switches off the system main relays SMR-B and SMR-G. It should be noted that switching off the system main relay SMR-B is only necessary if the system main relays SMR-B and SMR-G can be operated individually.

[0091] In step S202, the control unit 50 switches the switching elements SW10 and SW11 ON, and switches the switching elements SWR1 and SW12 OFF. This allows the discharge current of the battery pack 10 to flow via current path L1 or current path L2, which are located in Fig. Figure 7 shows the capacitor C11 being charged. The processes from step S203 to step S206 are identical to the processes from step S103 to step S106, which are related to... Fig. 5 are described. In the process in step S205, the control unit 50 determines that the battery pack 10 is not leaking if the voltage value Vc is lower than the threshold value Vth1, and terminates the process described in Fig. 9 process shown.

[0092] After capacitor C11 is charged, it is possible to discharge it via resistor R1 by switching switches SW10 and SW12 OFF and switching switches SW11 and SWR1 ON. This allows the voltage value Vc of capacitor C11 to be set to 0 [V] and the in Fig. Repeat the process shown in 9.

[0093] Next, a process is described to determine whether the system's main relay, SMR-B, has been blocked or not, using the parameters described in Fig. The first leak detection circuit 30 shown in Figure 7 is described using a flowchart that is shown in Figure 7. Fig. 10 is shown. The one in Fig. The process shown in 10 is executed by control unit 50. After the process in Fig. If the process shown in 9 determines that the battery pack 10 is not leaking, it is possible to determine the process shown in Fig. to carry out the process shown in 10.

[0094] It should be noted that the in Fig. The process shown in 10 is the process that is in Fig. The first leak detection circuit shown in section 7 uses 30, but a similar process can be achieved by using the circuit shown in section 7. Fig. The second leak detection circuit 40 shown in Figure 8 can be used. Therefore, a detailed description of the process using the second leak detection circuit 40 is omitted. When the second leak detection circuit 40 is used, it is possible to determine whether the system main relay SMR-G has been blocked or not.

[0095] If the process, which is similar to the one in Fig. In the process shown in Figure 10, which is carried out using the second leak detection circuit 40, the switching elements SW20, SW21, SW22, and SWR2 are used instead of the switching elements SW10, SW11, SW12, and SWR1. Additionally, the voltage value Vc is detected by the voltage sensor 41. Furthermore, the voltage value Vc, which corresponds to the capacitance of capacitor C22, is set to the voltage value Vth2, as described below.

[0096] In step S301, control unit 50 outputs the control signal to switch off the system main relays SMR-B and SMR-G. It should be noted that it is only necessary to output the control signal to switch off the system main relay SMR-B if the system main relays SMR-B and SMR-G can be operated individually.

[0097] In step S302, the control unit 50 switches the switching elements SW10 and SW12 ON, and switches the switching elements SWR1 and SW11 OFF. This allows the discharge current of the battery pack 10 to flow via current path L1 or current path L2, which are located in Fig. 7 are shown, connected to capacitor C12, and capacitor C12 is charged.

[0098] In step S303, the control unit 50 stands or waits until a predetermined time has elapsed since the end of the process in step S302. When the predetermined time has elapsed, in step S304, the control unit 50 detects the voltage value Vb using voltage sensor 21, and it also detects the voltage value Vc of capacitor C12 using voltage sensor 31.

[0099] In step S305, the control unit 50 determines whether the voltage value Vc detected in the process in step S304 is equal to the threshold value Vth2 or not. The process in step S305 is the same as the process in step S107, which is in Fig. Figure 5 shows that since the capacitance of capacitor C12 is smaller than the capacitance of capacitor C11, the threshold value Vth2 used in step S305 and the threshold value Vth2 used in step S107 are different. This means that the threshold value Vth2 used in step S305 is higher than the threshold value Vth2 used in step S107, due to the reduction in the capacitance of capacitor C12.

[0100] If, in step S305, the voltage value Vc is equal to the threshold value Vth2, control unit 50 determines in step S306 that the system main relay SMR-B has been blocked. The process in step S306 is the same as the process in step S108, which is described in Fig. 5 is shown. On the other hand, if there is no leakage from battery pack 10 and no blockage of the system main relay SMR-B, the voltage value Vc denotes the voltage value Vc_n at the time of normal conditions. As can be seen by using Fig. As described in section 6, in step S305 of the process, it is determined that the voltage value Vc is different from the threshold value Vth2, since the voltage value Vc_n is lower than the threshold value Vth2 during normal operation. In this case, the control unit 50 determines that the system main relay SMR-B is not blocked and terminates the process described in section 6. Fig. 10 shown process.

[0101] After capacitor C12 is charged, it can be discharged via resistor R1 by switching switches SW10 and SW11 OFF and switches SW12 and SWR1 ON. This allows the voltage value Vc of capacitor C12 to be set to 0 [V] and the Fig. Repeat the process shown in 10.

[0102] According to the exemplary embodiment, by appropriately using capacitor C11 or C12, as required by the situation, it is possible in the first leak detection circuit 30 to enable or facilitate the determination of the occurrence of leakage or stray / creep loss of the battery pack 10 and the determination of the occurrence of blocking of the system main relay SMR-B. The same effect as in the first leak detection circuit 30 can also be achieved in the second leak detection circuit 40.

[0103] A third embodiment of the invention is described. In this embodiment, the same components as those described in the first and second embodiments are designated by the same reference numerals, and their detailed descriptions are omitted. The following section mainly describes points that differ from the second embodiment.

[0104] In the second embodiment, capacitor C11 or C12 is used appropriately, as required by the situation, to determine whether battery pack 10 has leaked or system main relay SMR-B has jammed, using the first leak detection circuit 30. Similarly, capacitor C21 or C22 is used appropriately, as required by the situation, to determine whether battery pack 10 has leaked or system main relay SMR-G has jammed, using the second leak detection circuit 40. To use capacitor C11 or C12 appropriately, switching elements SW11 and SW12 must operate normally, respectively. Additionally, to use capacitor C21 or C22 appropriately, switching elements SW21 and SW22 must operate normally, respectively.

[0105] In this embodiment, it is determined whether the switching elements SW11 and SW12 are functioning normally or not, i.e., whether they are faulty or malfunctioning. Additionally, the embodiment determines whether the switching elements SW21 and SW22 are functioning normally or not, i.e., whether they are faulty or malfunctioning. The malfunction of each of the switching elements SW11, SW12, SW21, and SW22 includes a malfunction in which the switching element does not switch from ON to OFF and remains ON (referred to as the ON malfunction), and a malfunction in which the switching element does not switch from OFF to ON and remains OFF (referred to as the OFF malfunction).

[0106] A process for determining the fault of each of the switching elements SW11 and SW12, which are included in the first leak detection circuit 30, is described by using a flowchart shown in Fig. 11 is shown. The one in Fig. The process shown in Figure 11 is executed by the control unit 50. It should be noted that in this embodiment, the process for determining the fault of each of the switching elements SW11 and SW12 is described, and it is also possible to perform a similar process if the fault of each of the switching elements SW21 and SW22, which are included in the second leak detection circuit 40, is determined. Therefore, the detailed description of the process for determining the fault of each of the switching elements SW21 and SW22 is omitted.

[0107] If the process is similar to the one in Fig. In the process shown in Figure 11, which is carried out using the second leak detection circuit 40, the switching elements SW20, SW21, SW22, and SWR2 are used instead of the switching elements SW10, SW11, SW12, and SWR1. Additionally, the voltage value Vc is detected by the voltage sensor 41. Furthermore, the voltage values ​​Vc, corresponding to the capacitances of capacitors C21 and C22, are set as threshold values ​​Vth3 and Vth4, which are described below.

[0108] In step S401, control unit 50 switches on the system main relays SMR-B and SMR-G. It should be noted that it may only be necessary to switch on the system main relay SMR-B if the system main relays SMR-B and SMR-G can be operated individually.

[0109] In step S402, control unit 50 outputs the control signal to switch switching elements SW10 and SW11 ON and the control signal to switch switching elements SW12 and SWR1 OFF. In step S403, control unit 50 remains stationary or waits until a predetermined time has elapsed since the end of the process in step S402. Since the system main relay SMR-B is ON, the current flows in the relay that was previously in operation. Fig. 7 current path L2 shown, when the switching elements SW10 and SW11 are switched ON, and the capacitor C11 is thereby charged.

[0110] When the predetermined time has elapsed in step S403 of the process, the control unit 50 detects the voltage value Vb in step S404 using voltage sensor 21, and also detects the voltage value Vc using voltage sensor 31. In step S405, the control unit 50 determines whether the voltage value Vc detected in step S404 is equal to 0 V. Considering the detection error of voltage sensor 31, it is also possible in step S405 to determine whether the voltage value Vc falls within the detection error range, which has 0 V as the reference value. That is, it is possible to determine whether the voltage value Vc is essentially equal to 0 V.

[0111] If the voltage value Vc is 0 [V], the control unit 50 determines in step S406 that the switching element SW11 has an OFF fault. If, despite the fact that the control signal to switch the switching element SW11 ON is output in the process in step S402, the capacitor C11 is not charged and the voltage value Vc is 0 [V], it can be determined that the switching element SW11 has an OFF fault. In the process in step S406, it is possible, for example, to set a flag that indicates the fault of the switching element SW11 (fault flag). When the process in step S406 has been carried out, the control unit 50 terminates the process described in step S402. Fig. 11 shown process.

[0112] If the voltage value is not equal to 0 [V], the control unit 50 determines that the switching element SW11 does not exhibit the OFF fault. Subsequently, in step S407, the control unit 50 determines whether the voltage value Vc detected in the process in step S404 is not less than the threshold value Vth3. The threshold value Vth3 is the voltage value Vc when the capacitor C11 is charged with the current flowing in the current path L2. That is, the threshold value Vth3 corresponds to the voltage value Vc detected in step S404. Fig. The threshold Vth2 shown in section 6 corresponds to this.

[0113] Depending on the detection error of the voltage sensor, there are 31 cases in which the voltage value Vc falls below the threshold value Vth2. Considering this, it is possible to set a value lower than the threshold value Vth2 as the threshold value Vth3. Since the voltage value Vc of capacitor C11 depends on the voltage value Vb, it is possible to determine the threshold value Vth3, which corresponds to the voltage value Vb, by detecting the voltage value Vb, provided that a correspondence (a characteristic map or an arithmetic expression) between the threshold value (the voltage value Vc) Vth3 and the voltage value Vb has been predefined.

[0114] If, in step S407 of the process, the voltage value Vc is lower than the threshold value Vth3, the control unit 50 determines in step S408 that the switching element SW12 has the ON fault. According to the process in step S402, a control is performed to switch ON only the switching elements SW10 and SW11. If only the switching elements SW10 and SW11 are switched ON according to the control of the control unit 50, the capacitor C11 is charged with the current flowing in the current path L2, and thus the voltage value Vc of the capacitor C11 does not become lower than the threshold value Vth3.

[0115] However, if not only switching element SW11 but also switching element SW12 is ON, capacitors C11 and C12 are charged, and some of the charge that would otherwise accumulate in capacitor C11 is stored in capacitor C12. Therefore, the voltage value Vc of capacitor C11 does not rise to the threshold value Vth3, and the voltage value Vc detected by voltage sensor 31 is lower than the threshold value Vth3. If the voltage value Vc is lower than the threshold value Vth3, it can be determined that switching element SW12 is experiencing an ON fault. In the process in step S408, it is possible, for example, to set a flag that indicates the fault of switching element SW12 (fault flag). Once the process in step S408 has been carried out, the controller 50 terminates the process described in [the following text is incomplete and requires context to be translated accurately]. Fig. 11 shown process.

[0116] If, in step S407 of the process, the voltage value Vc is not less than the threshold value Vth3, the control unit 50 determines that the switching element SW12 does not exhibit the ON fault. Subsequently, in step S409, the control unit 50 switches the switching element SW10 OFF and switches the switching element SWR1 ON. This allows the capacitor C11 to be discharged via the resistor element R1.

[0117] In step S410, the control unit 50 stands or waits until a predetermined time has elapsed since the end of the process in step S409. During the process in step S410, capacitor C11 is discharged, so that the voltage value Vc of capacitor C11 becomes 0 [V]. It is possible to preset the predetermined time in consideration of this point.

[0118] When the predetermined time in the process in step S410 has elapsed, the control unit 50 outputs the control signal to switch the switching elements SW10 and SW12 ON and the control signal to switch the switching elements SW11 and SWR1 OFF in step S411. In step S412, the control unit 50 remains stationary or waits until a predetermined time has elapsed since the end of the process in step S411. Since the system main relay SMR-B is switched ON by the process in step S410, the capacitor C12 is charged with the current that was in the Fig. The current path L2 shown in section 7 flows when the switching elements SW10 and SW12 are ON.

[0119] When the predetermined time in the process in step S412 has elapsed, the control unit 50 detects the voltage value Vb in step S413 using voltage sensor 21, and also detects the voltage value Vc using voltage sensor 31. In step S414, the control unit 50 determines whether the voltage value Vc detected in the process in step S413 is equal to 0 [V] or not. Considering the detection error of voltage sensor 31, it can be determined whether the voltage value Vc falls within the range of the detection error, which has 0 [V] as the reference value. That is, it is possible to determine whether the voltage value Vc is essentially equal to 0 [V] or not.

[0120] If the voltage value Vc is 0 [V], the control unit 50 determines in step S415 that the switching element SW12 has an OFF fault. If, despite the fact that the switching element SW12 is controlled to ON by the process in step S411, the capacitor C12 is not charged and the voltage value Vc is 0 [V], it can be determined that the switching element SW12 has an OFF fault. In the process in step S415, it is possible, for example, to set a flag that indicates the fault of the switching element SW12 (fault flag). Once the process in step S415 has been carried out, the control unit 50 terminates the process described in [S411]. Fig. 11 shown process.

[0121] If the voltage value Vc in the process in step S414 is not equal to 0 [V], the control unit 50 determines that the switching element SW12 does not exhibit the OFF fault. Subsequently, the control unit 50 determines whether the voltage value Vc detected in the process in step S413 is not less than the threshold value Vth4 or not.

[0122] The threshold value Vth4 is the voltage value Vc when capacitor C12 is charged with the current flowing in current path L2. Specifically, the threshold value Vth4 corresponds to that in Fig. The threshold Vth2 shown in Figure 6 is shown. However, the threshold Vth4 is the voltage value Vc of capacitor C12, which has a capacitance smaller than that of capacitor C11. Therefore, the threshold Vth4 is higher than the threshold Vth2. Depending on the detection error of the voltage sensor 31, there are cases where the voltage value Vc becomes lower than the voltage value corresponding to the threshold Vth2. Considering this, it is possible to set a value lower than the voltage value corresponding to the threshold Vth2 as the threshold Vth4.

[0123] Since the voltage value Vc of capacitor C12 depends on the voltage value Vb, it is possible to determine the threshold value Vth4, which corresponds to the voltage value Vb, by detecting the voltage value Vb, if a correspondence (a characteristic map or an arithmetic expression) between the threshold value (the voltage value Vc) Vth4 and the voltage value Vb has been created or prepared in advance.

[0124] If, in step S416 of the process, the voltage value Vc is lower than the threshold value Vth4, the control unit 50 determines in step S417 that the switching element SW11 has the ON fault. According to the process in step S411, a control is performed to switch ON only the switching elements SW10 and SW12. If only the switching elements SW10 and SW12 are switched ON according to the control of the control unit 50, the capacitor C12 is charged with the current flowing in the current path L2, and thus the voltage value Vc of the capacitor C12 does not become lower than the threshold value Vth4.

[0125] However, if not only switching element SW12 but also switching element SW11 is ON, capacitors C11 and C12 are charged, and some of the charge that would otherwise accumulate in capacitor C12 is stored in capacitor C11. Therefore, the voltage value Vc of capacitor C12 does not rise to the threshold value Vth4, and the voltage value Vc detected by voltage sensor 31 is lower than the threshold value Vth4. If the voltage value Vc is lower than the threshold value Vth4, it can be determined that switching element SW11 is experiencing an ON fault. In the process in step S417, it is possible, for example, to set a flag that indicates the fault of switching element SW11 (fault flag). Once the process in step S417 has been carried out, the control unit 50 terminates the process described in Fig. 11 shown process.

[0126] If, in step S416 of the process, the voltage value Vc is not less than the threshold value Vth4, the control unit 50 can determine that the switching element SW11 does not have the ON fault. Subsequently, the control unit 50 terminates the process. Fig. 11 shown process.

[0127] According to the embodiment, it is possible to determine the fault (the ON fault or the OFF fault) of each of the switching elements SW11 and SW12 by monitoring the voltage value Vc while the control for switching the switching elements SW11 and SW12 between ON and OFF is being carried out. If the switching elements SW11 and SW12 are faulty or malfunctioning, even in the case where the Fig. 9 or Fig. The process shown in section 10 is carried out, but incorrect determinations are made. To control this, it is possible to modify the execution of the procedure shown in the document. Fig. 9 or Fig. To prevent the process shown in 10 if it is determined that the switching elements SW11 and SW12 are faulty or malfunctioning. If the fault flag in the Fig. If the process shown in 11 is set, it is possible, for example, to send the alarm to the user, as described in the first embodiment.

[0128] It should be noted that the order in which a fault is determined for each of the switching elements SW11 and SW12 does not depend on the process in Fig. The sequence shown in step 11 is restricted. For example, it is possible to perform the processes from step S402 to step S408 after the processes from step S411 to step S417 have been performed. Furthermore, it is possible to perform the process in step S407 before the process in step S405, and it is possible to perform the process in step S416 before the process in step S414.

[0129] Additionally, in the Fig. In the process shown in Figure 11, the system main relays SMR-B and SMR-G are switched ON in step S401, but the invention is not limited thereto. In particular, it is possible to carry out the processes in and after step S402 in a state in which the system main relays SMR-B and SMR-G are OFF.

[0130] In this case, it is possible to use the voltage value Vc as the threshold value Vth3 used in step S407 of the process, when capacitor C11 is charged with the current flowing in current path L1. The threshold value Vth3 at this point corresponds to the one in Fig. The threshold value Vth1 shown in step 6 is also possible. It is also possible to set a value lower than the threshold value Vth1, namely the threshold value Vth3.

[0131] Additionally, it is possible to use the voltage value Vc as the threshold value Vth4 used in step S416 of the process when capacitor C12 is charged by the current flowing in current path L1. The threshold value Vth4 at this point corresponds to the one in Fig. The threshold value Vth1 shown in Figure 6 is used. However, since the capacitance of capacitor C12 is smaller than the capacitance of capacitor C11, the threshold value Vth4 is higher than the threshold value Vth1. It is also possible to set a value lower than the voltage value Vc of capacitor C12, which corresponds to the threshold value Vth1, as the threshold value Vth4.

[0132] The malfunction of each of the switching elements SW11 and SW12 is indicated in the Fig. The process shown in Figure 11 determines the fault, and it is also possible to determine the fault of each of the switching elements SW10 and SWR1. Specifically, it is possible to determine the fault of each of the switching elements SW10 and SWR1 based on the voltage value Vc detected by the voltage sensor 31. The procedure (an example) for determining the fault of each of the switching elements SW10 and SWR1 is briefly described below.

[0133] If the control to switch normal switching elements SW11 and SW10 ON is performed after it has been determined that switching element SW11 is not faulty or malfunctioning, it can be determined that switching element SW10 is faulty in the OFF state if the voltage value Vc equals 0 [V]. Conversely, if the control to switch normal switching element SW11 ON and switching switching element SW10 OFF is performed after the voltage value Vc of capacitor C11 is set to 0 [V], it can be determined that switching element SW10 is faulty in the ON state if the voltage value Vc is higher than 0 [V].

[0134] If the control signal to switch the switching element SWR1 ON is executed and capacitor C11 or capacitor C12 is discharged, it can be determined that the switching element SWR1 is faulty in the OFF state if the voltage value Vc does not decrease. Conversely, it can be determined that the switching element SWR1 is faulty in the ON state if, despite the fact that the control signal to switch the switching element SWR1 OFF is executed, the voltage value Vc continues to decrease.

[0135] A fourth embodiment of the invention is described. In this embodiment, the same components as those described in the first three embodiments are designated by the same reference numerals, and their detailed descriptions are omitted. The following section mainly describes points that differ from the first three embodiments.

[0136] In the first embodiment, there are cases in which changes or fluctuations in capacitance occur in capacitor C11, which is included in the first leak detection circuit 30. Additionally, in the second embodiment, there are cases in which changes or fluctuations in capacitance occur in each of capacitors C11 and C12, which are included in the first leak detection circuit 30. There are also cases in which changes or fluctuations in capacitance occur in capacitors C21 and C22, which are also included in the second leak detection circuit 40. For example, there are cases in which changes or fluctuations in capacitance occur due to individual differences between capacitors C11, C12, C21, and C22. Furthermore, there are cases in which changes or fluctuations in capacitance occur due to temperature changes in the individual capacitors C11, C12, C21, and C22.

[0137] The following describes the case in which changes occur in the capacitance of capacitor C11. It should be noted that the same description applies to the case in which changes occur in the capacitance of each of capacitors C12, C21, and C22.

[0138] When changes occur in the capacitance of capacitor C11, changes also occur in the voltage value Vc of capacitor C11. Thus, as described in Fig. As shown in Figure 12, there are cases in which the voltage value Vc, which is detected by the voltage sensor 31 when the system main relay SMR-B has been blocked, is shifted from the threshold value Vth2 within the range of a displacement amount ΔVd1.

[0139] Similarly, there are cases in which the voltage value Vc, detected by the voltage sensor 31 when the battery pack 10 is not leaking and the system main relay SMR-B is not jammed, is shifted from the voltage value Vc_n during normal operation by a displacement amount ΔVd2. The threshold value Vth2 and the voltage value Vc_n, which are in Fig. The values ​​shown in 12 are equal to the threshold value Vth2 and the voltage value Vc_n, which are in Fig. Figure 6 shows that the displacement values ​​ΔVd1 and ΔVd2 change according to the individual difference and the temperature of condenser C11.

[0140] For example, if the voltage value Vc detected by the voltage sensor 31 is in Fig. The voltage value shown in Figure 12, Vc_cur, lies outside the threshold value Vth2 and the voltage value Vc_n during normal operation. Therefore, it is difficult to determine when the system main relay SMR-B will lock, even if the voltage value Vc_cur is detected.

[0141] In this embodiment, even if changes in the capacitance of capacitor C11 occur, it is possible to determine whether the system main relay SMR-B has been blocked or not in a state where changes in capacitance are not taken into account or checked.

[0142] When changes occur in the capacitance of capacitor C11, the direction of the shift in the voltage value Vc of capacitor C11 is the same, regardless of whether or not the system main relay SMR-B is locked. For example, if the voltage value Vc becomes higher than the threshold value Vth2 when the system main relay SMR-B is not locked, the voltage value Vc will be higher than the voltage value Vc_n at the time of normal operation when the system main relay SMR-B is not locked. That is, a curve (one in Fig. 6 curve shown), which is indicative of the correspondence between the threshold value Vth2 and the stress value Vb, and a curve (one in Fig. 6 (curve shown), which is indicative of the correspondence between the stress value Vc_n and the stress value Vb, are shifted by the same amount to the high or upper side of the stress value Vc.

[0143] On the other hand, if the voltage value Vc falls below the threshold value Vth2 when the system main relay SMR-B is blocked, then the voltage value Vc will be lower than the voltage value Vc_n during normal operation when the system main relay SMR-B is not blocked. This means that the curve (which is shown in Fig. 6 curve shown), which is indicative of the correspondence between the threshold value Vth2 and the stress value Vb, and the curve (which in Fig. 6 (curve shown), which is indicative of the correspondence between the voltage value Vc_n and the voltage value Vb, are shifted by the same amount to the lower side of the voltage value Vc.

[0144] As described above, the difference between the threshold value Vth2 and the voltage value Vc_n does not change at any given voltage value Vb, even if changes occur in the capacitance of capacitor C11. Based on this, it becomes easy to determine whether the system's main relay SMR-B has been blocked or not, even if changes occur in the capacitance of capacitor C11.

[0145] Specifically, under the condition that the voltage value Vb is unlikely to change, the voltage value Vc is detected when the system main relay SMR-B is switched ON, and the voltage value Vc when the system main relay SMR-B is switched OFF. It can then be determined that the system main relay SMR-B is not blocked if the difference (voltage difference) ΔVc between these voltage values ​​Vc corresponds to the difference between the threshold value Vth2 and the voltage value Vc_n.

[0146] On the other hand, if the system main relay SMR-B is blocked, the voltage value Vc when the system main relay SMR-B is switched OFF will be equal to the voltage value Vc when the system main relay SMR-B is switched ON. This means that the difference (voltage difference) ΔVc between these voltage values ​​Vc is equal to "0". Subsequently, even taking into account the detection error of the voltage sensor 31, the voltage difference ΔVc is smaller than the difference between the threshold value Vth2 and the voltage value Vc_n. Thus, it can be detected that the system main relay SMR-B is blocked.

[0147] The following describes a process for determining whether the system main relay SMR-B has been blocked or not, using the procedure described in Fig. The first leak detection circuit 30 shown in section 3 is described using a flowchart that is shown in Fig. 13 is shown. The one in Fig. The process shown in Figure 13 is executed by the control unit 50.

[0148] It should be noted that it is possible to implement a process similar to the one in Fig. The process shown in 13 is, by using the in Fig. The second leak detection circuit 40 shown in Figure 4 is to be carried out when the blockage of the system main relay SMR-G is determined, and therefore a detailed description of it is omitted. If the process, which is similar to the one in Fig. The process shown in 13 is, by using the in Fig. In the second leak detection circuit 40 shown in Figure 4, switching elements SW20 and SWR2 are used instead of switching elements SW10 and SWR1. Additionally, the voltage value Vc is detected by the voltage sensor 41.

[0149] In step S501, control unit 50 outputs the control signal to switch on the system main relays SMR-B and SMR-G. It should be noted that it is also possible to output the control signal to switch on only the system main relay SMR-B if the system main relays SMR-B and SMR-G can be operated individually.

[0150] In step S502, the control unit 50 switches the switching element SW10 ON and switches the switching element SWR1 OFF. In step S503, the control unit 50 remains stationary or waits until a predetermined time has elapsed since the end of the process in step S502. Since the switching element SW10 is ON, the current flows in the circuit described in Fig. 3 current path L2 shown, when the system main relay SMR-B is ON, and the capacitor C11 is charged.

[0151] When the predetermined time in the process in step S503 has elapsed, the control unit 50 detects the voltage value Vc (which is assumed to be a voltage value Vc1) in step S04 using the voltage sensor 31, and stores information regarding the voltage value Vc1 in the memory 51. In step S505, the control unit 50 switches the switching element SW10 OFF and switches the switching element SWR1 ON. This makes it possible to discharge the capacitor C11 via the resistor element R1.

[0152] In step S506, the control unit 50 stands or waits until a predetermined time has elapsed since the end of the process in step S505. During the process in step S506, capacitor C11 is discharged, so that the voltage value Vc of capacitor C11 becomes 0 [V]. It is possible to adjust the predetermined time appropriately in consideration of this point.

[0153] When the predetermined time in process step S506 has elapsed, control unit 50 outputs the control signal to switch off the system main relays SMR-B and SMR-G in step S507. It should be noted that it is possible to output the control signal to switch off only the system main relay SMR-B in process step S507 if the control signal to switch on only the system main relay SMR-B is / was output in process step S501.

[0154] In step S508, the control unit 50 switches the switching element SW10 ON and switches the switching element SWR1 OFF. In step S509, the control unit 50 detects the voltage value Vc (which is assumed to be a voltage value Vc2) by the voltage sensor 31 and stores information regarding the voltage value Vc2 in the memory 51.

[0155] In step S510, the control unit 50 calculates a voltage difference ΔVc based on the voltage values ​​Vc1 and Vc2, which were stored in memory 51 during the processes in steps S504 and S509. Specifically, the voltage difference ΔVc is calculated by subtracting the voltage value Vc2 from the voltage value Vc1. Subsequently, in step 510, the control unit 50 determines whether the calculated voltage difference ΔVc is less than the threshold value ΔVth. As described above, the threshold value ΔVth is the difference between the threshold value Vth2 and the voltage value Vc_n, and it can be determined in advance.

[0156] In the process in step S511, the control unit 50 determines that the system main relay SMR-B has been blocked if, in the process in step S510, the voltage value ΔVc is less than the threshold value ΔVth. In this case, the control unit 50 can set the flag regarding the occurrence of the blocking (the blocking flag described above). On the other hand, if, in the process in step S510, the voltage difference ΔVc is not less than the threshold value ΔVth, the control unit 50 determines that the system main relay SMR-B is not blocked and terminates the process in step S510. Fig. 13 shown process.

[0157] Although the in Fig. 3 shown first leak detection circuit 30 in the in Fig. Using the process shown in 13, it is also possible to carry out the process which is similar to the one in Fig. 13 process shown, if the in Fig. The first leak detection circuit 30 shown in section 7 is used, or the one in Fig. The second leak detection circuit 40 shown in Figure 8 is used. If the Fig. When the first leak detection circuit 30 shown in Figure 7 is used, capacitor C12 can be charged. In this case, the voltage value Vc of capacitor C12 is detected when the system main relay SMR-B is switched ON, and the voltage value Vc of capacitor C12 is detected when the system main relay SMR-B is switched OFF. Subsequently, it is possible to determine whether the system main relay SMR-B has been blocked or not by calculating the difference ΔVc between these voltage values ​​Vc and comparing the voltage difference ΔVc with the threshold value ΔVth.

[0158] If the in Fig.When the second leak detection circuit 40 shown in Figure 8 is used, capacitor C22 can be charged. In this case, the voltage value Vc of capacitor C22 is detected when the system main relay SMR-G is switched ON, and the voltage value Vc of capacitor C22 is detected when the system main relay SMR-G is switched OFF. Subsequently, it is possible to determine whether the system main relay SMR-G has been blocked or not by calculating the difference ΔVc between these voltage values ​​Vc and comparing the voltage difference ΔVc with the threshold value ΔVth.

[0159] According to the exemplary embodiment, by calculating the voltage difference ΔVc using the same capacitor C11, it is possible to determine whether the system main relay SMR-B has been blocked or not, even in a state where the individual difference of capacitor C11 is not considered or checked. Additionally, it is possible to suppress or reduce changes in the voltage value Vc resulting from temperature changes in capacitor C11 by detecting the voltage values ​​Vc1 and Vc2 within a short time period. Thus, it is possible to determine whether the system main relay SMR-B has been blocked or not, even in a state where the temperature change of capacitor C11 is not considered or checked. Therefore, in this exemplary embodiment, it is possible to determine whether changes in the capacitance of capacitor C11 have been blocked or not, even in a state where changes in the capacitance of capacitor C11 are not considered or checked.to be checked / verified to determine whether the system main relay SMR-B has been blocked or not.

Claims

[1] Electrical storage system with: an electrical storage device (10); a load (20); a line (PL) configured to connect the electrical storage device (10) and the load (20); a relay (SMR-G) that is provided in the line (PL); a capacitor (C11) which has one end connected to the electrical storage device (10) and the other end connected to a ground; a voltage sensor (21) configured to detect a voltage value of the capacitor (C11); a first insulation resistance (RB) which is set up between the electrical storage device (10) and the ground; a second insulation resistor (RL) which is installed between the load (20) and the ground; a first current path (L1) which includes the first insulation resistance (RB); a second current path (L2) comprising the conductor (PL) and the second insulation resistance (RL); and a control unit (50) that is configured to (a) Controlling ON and OFF of the relay (SMR-G), and (b) Determine that the relay (SMR-G) is blocked in an ON state if the voltage value is substantially equal to a second voltage value in a case where control to turn off the relay (SMR-G) is carried out, where a first resistance value is higher than a second resistance value, the second voltage value is higher than a first voltage value, the first resistance value is a resistance value of the first insulation resistance (RB), the second resistance value is a resistance value of the second insulation resistance (RL), the first voltage value is a voltage value when a discharge current of the electrical storage device (10) flows to the capacitor (C11) in the first current path (L1), the second voltage value is a voltage value when the discharge current of the electrical storage device (10) flows to the capacitor (C11) in the second current path (L2). [2] Electrical storage system with: an electrical storage device (10); a load (20); a line (PL) configured to connect the electrical storage device (10) and the load (20); a relay (SMR-G) that is provided in the line (PL); a capacitor (C11) which has one end connected to the electrical storage device (10) and the other end connected to a ground; a voltage sensor (21) configured to detect a voltage value of the capacitor (C11); a first insulation resistance (RB) which is set up between the electrical storage device (10) and the ground; a second insulation resistor (RL) which is installed between the load (20) and the ground; a first current path (L1) which includes the first insulation resistance (RB); a second current path (L2) comprising the conductor (PL) and the second insulation resistance (RL); and a control unit (50) that is configured to (a) Controlling ON and OFF of the relay (SMR-G), and (b) Determine that the relay (SMR-G) is blocked in an ON state if, in a case where control to switch the relay (SMR-G) between ON and OFF is performed, a voltage difference is less than a difference between a first voltage value and a second voltage value, where a first resistance value is higher than a second resistance value, the first voltage value is lower than the second voltage value, the first resistance value is a resistance value of the first insulation resistance (RB), the second resistance value is a resistance value of the second insulation resistance (RL), the first voltage value is a voltage value when a discharge current of the electrical storage device (10) flows to the capacitor (C11) in the first current path (L1), the second voltage value is a voltage value when the discharge current of the electrical storage device (10) flows to the capacitor (C11) in the second current path (L2), the voltage difference is a voltage difference between the voltage value detected by the voltage sensor (21) when a control to switch on the relay (SMR-G) is performed and the voltage value detected by the voltage sensor (21).when a control is performed to switch off the relay (SMR-G), it is. [3] Electrical storage system according to claim 1 or 2, wherein the capacitor (C11, C12) comprises: a first capacitor (C11), and a second capacitor (C12) connected in parallel to the first capacitor (C11), wherein the capacitance of the second capacitor (C12) is less than the capacitance of the first capacitor (C11), a first switching element connected in series with the first capacitor (C11), a second switching element connected in series with the second capacitor (C12) and in parallel with the first capacitor (C11) and the first switching element, and the control unit (50) is configured to Switching ON the first switching element and switching OFF the second switching element when the control unit (50) determines that a leak has occurred as a result of a decrease in the first resistance value, Determine that the leakage resulting from the reduction of the first resistance value has occurred if the voltage value detected by the voltage sensor (21) is higher than or equal to a third voltage value, where the third voltage value is a value higher than the second voltage value, and Switching OFF the first switching element and ON the second switching element when the control unit (50) determines that the relay (SMR-G) is blocked. [4] Electrical storage system according to claim 3, wherein the control unit (50) is configured to (a) Determine that the first switching element is faulty in an OFF state when a control is performed to turn the first switching element ON and a control is performed to turn the second switching element OFF, and when the voltage value detected by the voltage sensor (21) is substantially 0, and (b) Determine that the second switching element is faulty in an ON state if the voltage value detected by the voltage sensor (21) is lower than a fourth voltage value, the fourth voltage value being a voltage value when the discharge current of the electrical storage device (10) flows to the first capacitor (C11) in the first current path (L1) or the second current path (L2). [5] Electrical storage system according to claim 3 or 4, wherein the control unit (50) is configured to (a) Determine that the second switching element is faulty in the OFF state when control is performed to switch the first switching element OFF and control is performed to switch the second switching element ON, and when the voltage value detected by the voltage sensor (21) is substantially 0, and (b) Determine that the first switching element is faulty in the ON state if the voltage value detected by the voltage sensor (21) is lower than a fifth voltage value, the fifth voltage value being a voltage value when the discharge current of the electrical storage device (10) flows to the second capacitor (C12) in the first current path (L1) or the second current path (L2). [6] Electrical storage system with: an electrical storage device (10); a load (20); a line (PL) configured to connect the electrical storage device (10) and the load (20); a relay (SMR-G) that is provided in the line (PL); a capacitor (C11) which has one end connected to the electrical storage device (10) and the other end connected to a ground; a voltage sensor (21) configured to detect a voltage value of the capacitor (C11); a first insulation resistance (RB) which is set up between the electrical storage device (10) and the ground; a second insulation resistance (RL) which is installed between the load (20) and earth and has a resistance value that differs from a resistance value of the first insulation resistance (RB); a first current path (L1) which includes the first insulation resistance (RB); a second current path (L2) comprising the conductor (PL) and the second insulation resistance (RL); and a control unit (50) that is configured to Determine that the relay (SMR-G) is blocked in an ON state when a voltage value is substantially equal to a predetermined voltage value in a case where a signal to switch the relay (SMR-G) OFF is output. wherein the predetermined voltage value is a voltage value of the capacitor (C11) which is detected by the voltage sensor (21) when a discharge current of the electrical storage device (10) flows to the capacitor (C11) in the second current path (L2). [7] Electrical storage system with: an electrical storage device (10); a load (20); a line (PL) configured to connect the electrical storage device (10) and the load (20); a relay (SMR-G) that is provided in the line (PL); a capacitor (C11) which has one end connected to the electrical storage device (10) and the other end connected to a ground; a voltage sensor (21) configured to detect a voltage value of the capacitor (C11); a first insulation resistance (RB) which is set up between the electrical storage device (10) and the ground; a second insulation resistor (RL) which is installed between the load (20) and the ground; a first current path (L1) which includes the first insulation resistance (RB); a second current path (L2) comprising the conductor (PL) and the second insulation resistance (RL); and a control unit (50) that is configured to Determine that the relay (SMR-G) is blocked in an ON state when a predetermined voltage difference is less than a difference between a first voltage value and a second voltage value in a case where a signal to switch the relay (SMR-G) between ON and OFF is output. wherein the first voltage value is a voltage value of the capacitor (C11) which is detected by the voltage sensor (21) when a discharge current of the electrical storage device (10) flows to the capacitor (C11) in the first current path (L1), wherein the second voltage value is a voltage value of the capacitor (C11) which is detected by the voltage sensor (21) when the discharge current of the electrical storage device (10) flows to the capacitor (C11) in the second current path (L2), where the predetermined voltage difference is a voltage difference between a voltage value of the capacitor (C11) detected by the voltage sensor (21) when a signal to switch the relay (SMR-G) ON is output, and a voltage value of the capacitor (C11) detected by the voltage sensor (21) when a signal to switch the relay (SMR-G) OFF is output.

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