Battery system

Abstract

The battery system includes a battery, a first main relay, and a second main relay. The battery has a positive electrode and a negative electrode. The first main relay is connected in series with the positive electrode side of the battery. The second main relay is connected in series with the negative electrode side of the battery. At least one of the first main relay and the second main relay includes a relay group in which a plurality of relays are connected in parallel.

Description

Technical Field

[0001] The present invention relates to a battery system. Background Art

[0002] A battery system including a plurality of battery modules and a plurality of switches is disclosed in Japanese Unexamined Patent Application Publication No. 2019-129568. The plurality of battery modules can switch between a series-connected state (i.e., a series state) and a parallel-connected state (i.e., a parallel state) through the plurality of switches. In the battery system, the series state and the parallel state of the plurality of battery modules are switched according to the degree of deterioration of the battery modules. According to this battery system, it is possible to appropriately prevent the battery system from becoming unusable due to the inability to control the opening and closing of the switches.

[0003] A charging control device for a power supply device capable of switching the connection mode of a plurality of power storage elements to series and parallel is disclosed in Japanese Unexamined Patent Application Publication No. 2013-081316. The charging control device selects the connection mode at the start of charging based on the temperature and SOC of the power supply device. The charging control device controls the charging current in parallel using an upper limit value larger than the upper limit value of the charging current in series input to the power supply device. According to this charging control device, deterioration of battery performance can be suppressed and the power supply device can be charged and discharged in a short time.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-129568

[0007] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2013-081316 Summary of the Invention

[0008] The inventors of the present application considered improving the convenience of the battery system.

[0009] The battery system disclosed herein includes a battery, a first main relay, and a second main relay. The battery has a positive electrode and a negative electrode. The first main relay is connected in series with the positive electrode side of the battery. The second main relay is connected in series with the negative electrode side of the battery. At least one of the first main relay and the second main relay includes a relay group in which a plurality of relays are connected in parallel. The plurality of relays are individually controlled to switch between a closed state and an open state. In this battery system, the convenience of the battery system is improved. Brief Description of the Drawings

[0010] Figure 1 is a schematic diagram showing the battery system 100.

[0011] Figure 2 is a flowchart showing the processing executed in the controller 40.

[0012] Figure 3 It is a graph showing the changes in current and voltage during charging and the states of relays 21, 22, 31, and 32.

[0013] Figure 4 It is a schematic diagram showing the battery system 100A. Detailed implementation

[0014] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiments described herein are of course not intended to particularly limit the present invention. Each drawing is a schematic illustration and does not reflect the actual object. In addition, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repeated descriptions are appropriately omitted. In this specification, expressions such as "X to Y" indicating a numerical range mean "X or more and Y or less" unless otherwise specified.

[0015] <Battery system 100>

[0016] Figure 1 It is a schematic diagram showing the battery system 100. As Figure 1 shown, the battery system 100 includes a battery 10, a first main relay 20, and a second main relay 30. The battery system 100 includes a controller 40. The controller 40 individually controls the opening and closing of each of the relays included in the first main relay 20 and the second main relay 30. The battery system 100 is an aggregate that includes not only a battery also known as a battery pack but also a configuration for controlling the battery. Connection parts 101 to 103 are provided in the battery system 100. The connection parts 101 to 103 are parts configured to be connectable to an external charger 80 and a load 70.

[0017] In the present embodiment, the battery system 100 is connected to the load 70 via the connection part 101. Electric power is supplied from the battery 10 of the battery system 100 to the load 70. In the present embodiment, the load 70 is a load of an electric vehicle and may be composed of an electric motor and an inverter of the vehicle. It is not limited to this mode, and the battery system 100 can also be applied to cases other than the battery system mounted on an electric vehicle.

[0018] <Battery 10>

[0019] The battery 10 has a positive electrode and a negative electrode. The battery 10 is a power storage device capable of extracting electric energy. Electric power supplied from the charger 80 is stored in the battery 10. The battery 10 is connected to the load 70 via the connection part 101. The battery 10 supplies electric power to the load 70.

[0020] The battery 10 in the battery system includes a secondary battery that can be repeatedly charged and discharged by allowing charge carriers to move between a pair of electrodes (a positive electrode and a negative electrode) via an electrolyte. For example, the battery 10 includes a lithium-ion secondary battery, a nickel-metal hydride battery, etc. The battery 10 can be a single cell 10a or a battery pack 10A in which a plurality of single cells 10a are electrically connected to each other via a bus bar. In the present embodiment, as the battery 10, two battery packs 10A are included. The two battery packs 10A are connected in series. The single cells constituting the battery pack can be connected in series, in parallel, or in a combination of series and parallel. In the present embodiment, in the battery pack 10A, a plurality of single cells 10a are connected in series.

[0021] The battery 10 of the battery system 100 is charged by a charger 80. The battery 10 is connected to the charger 80 via connection portions 102 and 103. The battery system 100 is configured to be connectable to either a normal charger (hereinafter also referred to as "normal charger") 82 for normal charging and a rapid charger (hereinafter also referred to as "rapid charger") 83 for rapid charging. The battery system 100 can be connected to the normal charger 82 via the connection portion 102. The battery system 100 can be connected to the rapid charger 83 via the connection portion 103. The normal charger 82 and the rapid charger 83 can also be connected to a common connection portion.

[0022] In the normal charger 82 for in-vehicle batteries, the output of the normal charger 82 can be about 1 kW to 6 kW. The current flowing through the battery 10 during charging by the normal charger 82 can be about 5 A to 15 A. The rapid charger 83 is a charger for charging with an output higher than that of the normal charger 82. In the rapid charger 83 for in-vehicle batteries, the output of the rapid charger 83 can be about 50 kW to 350 kW. The current flowing through the battery 10 during charging by the rapid charger 83 can be about 100 A to 400 A. In addition, the output and current during normal charging and rapid charging are not limited to the above values. The output and current during normal charging and rapid charging can vary depending on the usage form of the battery system 100, etc. For example, when the battery system 100 is used in mobile terminals such as laptop computers, smartphones, and tablet terminals, the output and current during normal charging and rapid charging are lower than the above values.

[0023] The battery 10 and the connection part 101 are connected via connection lines 101a and 101b. The connection line 101a is connected to the positive electrode side of the battery 10. The connection line 101b is connected to the negative electrode side of the battery 10. The connection lines 102a and 102b extending from the connection part 102 are respectively connected to the connection lines 101a and 101b. The connection lines 103a and 103b extending from the connection part 103 are respectively connected to the connection lines 101a and 101b. At one end of the connection lines 101a and 101b extending from the connection part 101, a first main relay 20 and a second main relay 30 are respectively provided.

[0024] A first main relay 20 and a second main relay 30 are provided between the battery 10 and the connection part 101. The connection and disconnection with the load 70 and the charger 80 are switched by the first main relay 20 and the second main relay 30.

[0025] <The first main relay 20>

[0026] The first main relay 20 is connected in series with the positive electrode side of the battery 10. The first main relay 20 switches the connection state between the battery 10, the load 70, and the charger 80 on the positive electrode side of the battery 10. The first main relay 20 includes relay groups 21 and 22 (a plurality of relays 21 and 22). In the relay groups 21 and 22, the plurality of relays 21 and 22 are connected in parallel. The plurality of relays 21 and 22 are each configured to be able to individually switch between an open state and a closed state.

[0027] <The second main relay 30>

[0028] The second main relay 30 is connected in series with the negative electrode side of the battery 10. The second main relay 30 switches the connection state between the battery 10, the load 70, and the charger 80 on the negative electrode side of the battery 10. Similar to the first main relay 20, the second main relay 30 includes relay groups 31 and 32 (a plurality of relays 31 and 32). In the relay groups 31 and 32, the plurality of relays 31 and 32 are connected in parallel. The plurality of relays 31 and 32 are each configured to be able to individually switch between an open state and a closed state. There is no particular limitation as long as the relays 21, 22, 31, and 32 can switch the connection and disconnection of the battery 10, the load 70, and the charger 80. As the relays 21, 22, 31, and 32, an electromechanical relay or a semiconductor relay can be used.

[0029] In the battery system 100, both the first main relay 20 and the second main relay 30 include relay groups in which a plurality of relays (relays 21 and 22 in the first main relay 20, and relays 31 and 32 in the second main relay 30) are connected in parallel.

[0030] In the first main relay 20, a pre-charge circuit 25 that prevents inrush current from flowing into the load 70 and the battery 10 is connected in parallel.

[0031] <Pre-charge circuit 25>

[0032] The pre-charge circuit 25 is provided on the positive electrode side of the battery 10. The pre-charge circuit 25 is a circuit in which a pre-charge resistor 26 and a pre-charge relay 27 are connected in series. The pre-charge circuit 25 is a circuit that prevents inrush current from flowing when power is supplied from the battery system 100 to the load 70, when power is supplied from the charger 80 to the battery system 100, and so on.

[0033] Before the load 70 is started, the first main relay 20, the second main relay 30, and the pre-charge relay 27 are set to the open state. When the load 70 is started, the second main relay 30 and the pre-charge relay 27 are switched to the closed state. The switching of the pre-charge relay 27 is controlled by the controller 40. The load 70 is connected to the battery system 100 via the pre-charge circuit 25. At this time, by providing the pre-charge resistor 26 in the pre-charge circuit 25, power is supplied from the battery 10 to the load 70 with a low current. Then, with the potential of the load 70 raised, the first main relay 20 is set to the closed state, and then the pre-charge relay 27 is set to the open state. Thereby, a large current can be prevented from flowing when the load 70 is started.

[0034] In addition, before the battery 10 is charged, the first main relay 20, the second main relay 30, and the pre-charge relay 27 are set to the open state. When the battery 10 is charged, the second main relay 30 and the pre-charge relay 27 are switched to the closed state. The load 70 is connected to the charger 80 via the pre-charge circuit 25. At this time, by providing the pre-charge resistor 26 in the pre-charge circuit 25, power is supplied from the charger 80 to the battery 10 with a low current. Then, with the potential of the battery 10 raised, the first main relay 20 is set to the closed state, and then the pre-charge relay 27 is set to the open state. Thereby, a large current can be prevented from flowing at the start of charging of the battery 10. The opening and closing of the above pre-charge relay 27 is also referred to as a pre-charge series operation.

[0035] However, when charging a battery, in order to shorten the charging time, the battery is sometimes rapidly charged. When rapidly charging the battery, it is necessary to charge the battery with a large output. In addition, in order to achieve long-term operation with a single charge, a battery with a large capacity is sometimes used. In this case, in order to shorten the charging time, the battery is sometimes rapidly charged. Furthermore, when supplying (discharging) the electric energy charged in the battery to an external load, a large current may flow to the external load depending on the usage pattern of the battery system. Thus, a large current sometimes flows in the charge and discharge circuit of the battery. When a current flows, heat is generated due to the resistance of the components constituting the circuit in the charge and discharge circuit. For example, in a relay that switches the connection between the battery and the load, heat is generated depending on the contact resistance in the closed state. This heat becomes greater as the current flowing through the circuit becomes larger. In addition, in order to reduce the contact resistance in the relay to reduce heat generation, a large relay designed according to the charge and discharge current is sometimes used as the main relay.

[0036] In the above-described embodiment, the battery system 100 includes a battery 10, a first main relay 20, and a second main relay 30. The battery 10 has a positive electrode and a negative electrode. The first main relay 20 is connected in series with the positive electrode side of the battery 10. The second main relay 30 is connected in series with the negative electrode side of the battery 10. The first main relay 20 includes a relay group 21, 22 in which a plurality of relays 21, 22 are connected in parallel. According to this configuration, in the first main relay 20, the current flowing to the relays 21, 22 is divided. Thus, the heat generation of each of the relays 21, 22 becomes smaller. As a result, in the relays 21, 22, it is difficult for problems (such as thermal welding) caused by deterioration of the relays 21, 22 due to heat to occur. This battery system 100 can also easily cope with rapid charge and discharge in which a large current flows through the battery 10, and the convenience of the battery system 100 is improved.

[0037] In addition, compared with the case where a large relay is used as the main relay, the battery system 100 can reduce the weight of the relay. As a result, the energy for driving the relay can be reduced. In the battery system 100, since a small relay can be used, the options for component selection increase, and the manufacturing cost can be reduced.

[0038] In the above-described embodiment, similar to the first main relay 20, the second main relay 30 includes a relay group 31, 32 in which a plurality of relays 31, 32 are connected in parallel. Both the first main relay 20 and the second main relay 30 include relay groups in which a plurality of relays are connected in parallel. According to this configuration, on both the positive electrode side and the negative electrode side of the battery 10, the heat generation of each of the relays 21, 22, 31, 32 becomes smaller. In addition, since the relay groups are provided on both the positive electrode side and the negative electrode side of the battery 10, the reliability of the battery system 100 can be improved due to redundancy.

[0039] In addition, the relay group does not necessarily have to be provided in both the first main relay 20 and the second main relay 30. The relay group may be provided only in the first main relay 20 or only in the second main relay 30. Further, in the above-described embodiment, the first main relay 20 and the second main relay 30 each include two relays. However, the form is not limited thereto, and the first main relay 20 and the second main relay 30 may each include three or more relays. The number of relays may also be determined based on the value of the current that can flow in the charge and discharge circuit.

[0040] In the battery system 100, the switching between the open state and the closed state of the plurality of relays 21, 22, 31, 32 is controlled by the controller 40.

[0041] <Controller 40>

[0042] The controller 40 individually switches the closed state and the open state of the plurality of relays 21, 22, 31, 32 according to a predetermined condition. The controller 40 may be, for example, a computer such as an ECU (Electronic Control Unit), a microcomputer-mounted circuit board, etc. The computer performs the required functions according to a predetermined program, for example. Each function of the computer is processed through the cooperation of an arithmetic device (also referred to as a processor, CPU (Central Processing Unit), MPU (Micro-Processing Unit)) of the computer, a storage device (memory or hard disk, etc.), and software.

[0043] The controller 40 includes a communication unit 41, a mode determination unit 42, a mode setting unit 43, a permissible current determination unit 44, an instruction unit 45, a voltage determination unit 46, a current determination unit 47, an end determination unit 48, and a storage unit 49. Each part 41 to 49 of the controller 40 may be implemented by one or more processors or may be assembled into a circuit. The communication unit 41 of the controller 40 is configured to be able to communicate with the current sensor 50, the voltage sensor 60, and the upper controller 75.

[0044] The battery system 100 includes a current sensor 50. The current sensor 50 measures the charge and discharge current flowing through the battery 10. In the present embodiment, the current sensor 50 is provided between the battery 10 and the first main relay 20. The position of the current sensor 50 is not particularly limited. The charge and discharge current measured by the current sensor 50 is sent to the controller 40.

[0045] The battery system 100 includes a voltage sensor 60. The voltage sensor 60 measures the voltage of the battery 10. In the present embodiment, the voltage sensors 60 are respectively provided for the battery packs 10A connected in series. The voltage sensor 60 can measure the voltage of the corresponding battery pack 10A respectively, and can also measure the voltages of the individual cells 10a that make up the battery pack 10A. The voltages of the battery packs 10A measured by the voltage sensors 60 respectively are sent to the controller 40.

[0046] The controller 40 is configured to communicate with the upper controller 75. In the present embodiment, the upper controller 75 is the controller of an electric vehicle equipped with the battery system 100 and the load 70, and is also referred to as the in-vehicle ECU.

[0047] Hereinafter, the control of the switching of the open and closed states of the plurality of relays 21, 22, 31, and 32 by the controller 40 will be described. Figure 2 It is a flowchart showing the processing executed in the controller 40. When the battery system 100 is started, charging / discharging and the control of the relays 21, 22, 31, and 32 start. When the battery system 100 is started, the relays 21, 22, 31, and 32 and the pre-charge relay 27 are in the open state.

[0048] In Figure 2 In step S1, the mode determination unit 42 of the controller 40 determines the charge / discharge mode. Here, as the charge / discharge mode, a rapid charge mode, a normal charge mode, and a load charge / discharge mode are set. The rapid charge mode is the mode when the rapid charger 83 is connected to the connection part 103. The normal charge mode is the mode when the normal charger 82 is connected to the connection part 102. The load charge / discharge mode is the mode when the charger 80 is not connected to the connection parts 102 and 103, but power is supplied from the battery 10 to the load 70 via the connection part 101. In the present embodiment, when the vehicle is not connected to the charger 80 and is driving or parked, the load charge / discharge mode is set. In the load charge / discharge mode, power can also be supplied from the load 70 to the battery system 100 side.

[0049] The upper controller 75 recognizes the connection states of the connection parts 101 to 103, and sends a signal corresponding to the mode to be set to the controller 40. The controller 40 receives the signal sent from the upper controller 75. In step S1, the mode determination unit 42 determines the charge / discharge mode based on the signal from the upper controller 75. In step S1, if the mode determination unit 42 determines that it is the rapid charge mode, it proceeds to step S21.

[0050] <Rapid charge mode>

[0051] In Figure 2In step S21, the mode setting unit 43 sets the control of the controller 40 to the rapid charging mode. Next, in Figure 2 In step S22, the allowable current determination unit 44 determines the allowable current during charging of the battery 10. The allowable current can be determined based on the remaining capacity (SOC) of the battery, the degradation state (SOH) of the battery, the temperature of the battery, etc. The allowable current can also be determined considering the thermal boundary characteristics of the components (relays 21, 22, 31, 32 in this embodiment) in the charge and discharge circuit. The allowable current can also be determined based on the resistance of the components, the current flowing through the components, and the predetermined time for which the current flows.

[0052] Figure 3 is a graph showing the changes in current and voltage during charging and the states of relays 21, 22, 31, 32. In this embodiment, the battery 10 is charged by so-called CCCV (Constant Current, Constant Voltage) charging. As Figure 3 shown, before the voltage of the battery 10 reaches a predetermined threshold Vth1, the battery 10 is charged with a constant current. If the voltage of the battery 10 reaches above the predetermined threshold Vth1, the battery 10 is charged with a constant voltage. In addition, the charging of the battery 10 is not limited to CCCV charging, and it can also be charged by other known charging methods.

[0053] In Figure 2 In step S23, the indication unit 45 controls the main relay group (relays 21, 22 of the first main relay 20 and relays 31, 32 of the second main relay 30) to the closed state. Thus, during rapid charging, a plurality of relays (relays 21, 22 of the first main relay 20 and relays 31, 32 of the second main relay 30) are switched to the closed state. In addition, relays 21, 22 can be set to the closed state after the pre-charging series operation.

[0054] In Figure 2 In step S24, the charging of the battery 10 starts. During charging, the current Ibat1 of the battery 10 measured by the current sensor 50 and the voltage Vbat1 of the battery 10 measured by the voltage sensor 60 are appropriately sent to the controller 40. The battery 10 is charged according to the allowable current determined in step S22.

[0055] In Figure 2 In step S25, the voltage determination unit 46 determines whether the voltage Vbat1 of the battery 10 is above the threshold Vth1. When the voltage Vbat1 of the battery 10 is smaller than the threshold Vth1 (No), it returns to step S24 and continues charging. At this time, the battery 10 continues to be charged with a constant current, and the voltage Vbat1 rises (refer toFigure 3 )。When the voltage Vbat1 of the battery 10 becomes equal to or higher than the threshold value Vth1, step S26 is entered. After a while when the voltage Vbat1 becomes equal to or higher than the threshold value Vth1, the charging method of the battery 10 is switched from constant current charging to constant voltage charging.

[0056] In Figure 2 In step S26, the current determination unit 47 determines whether the current Ibat1 of the battery 10 is equal to or lower than the threshold value Ith1. When the current Ibat1 of the battery 10 is greater than the threshold value Ith1 (No), the process returns to step S24 to continue charging. If the battery 10 is charged at a constant voltage, the current Ibat1 decreases (see Figure 3 ). When the current Ibat1 of the battery 10 becomes equal to or lower than the threshold value Ith1 (Yes), step S27 is entered.

[0057] In Figure 2 In step S27, the instruction unit 45 controls some of the relays among the relays 21 and 22 of the first main relay 20 and the relays 31 and 32 of the second main relay 30 to the open state. In the present embodiment, the instruction unit 45 controls the relay 22 of the first main relay 20 and the relay 32 of the second main relay 30 to the open state. In this way, when the controller 40 performs rapid charge and discharge, when the voltage Vbat1 is equal to or higher than a predetermined value and the current Ibat1 is equal to or lower than a predetermined value, at least one of the relays 22 and 32 among the plurality of relays 21, 22, 31, and 32 is switched to the open state. Thereby, when the current Ibat1 is low, it is possible to suppress defective conditions of the relay due to heat and reduce the power consumption of driving the relays 22 and 32.

[0058] In Figure 2 In step S28, the end determination unit 48 determines whether the charging of the battery 10 is completed. The determination condition for the completion of charging is not particularly limited. The determination condition for the completion of charging can be set according to whether the target power has been fully charged. The determination condition for the completion of charging can be set according to, for example, the battery remaining amount, voltage, current, charging time, etc. When it is determined that the charging is not completed (No), the charging continues. When it is determined that the charging is completed (Yes), the charging of the battery 10 is completed, and the power supply from the rapid charger 83 is stopped. The instruction unit 45 can control the relays 21, 22, 31, and 32 to the open state.

[0059] In the above-described embodiment, when the controller 40 performs rapid charge and discharge, the plurality of relays 21, 22, 31, and 32 are switched to the closed state. Thereby, it is difficult to occur defective conditions caused by deterioration of the relays 21, 22, 31, and 32 due to heat generated during rapid charge and discharge.

[0060] <Normal charging mode>

[0061] In Figure 2 step S1 of Figure 2 if the mode determination unit 42 determines it is the normal charging mode, it proceeds to step S31. In Figure 2 step S31 of

[0062] In Figure 2 step S32 of

[0063] In Figure 2 step S33 of Figure 2 step S34 of

[0064] In Figure 2 step S34 of

[0065] Herein, the case of rapid charging or normal charging of the battery 10 of the battery system 100 has been described, but it is not limited to this method. The processing of the above-mentioned controller 40 can also be applied to the case of supplying power (discharging) from the battery 10 of the battery system 100 to the load 70 or the like. For example, when rapid discharging or normal discharging is set as the usage form of the battery system 100, the above-mentioned "rapid charging" and "normal charging" can be appropriately renamed as "rapid discharging" and "normal discharging".

[0066] <Load charge and discharge mode>

[0067] In Figure 2 In step S1, if the mode determination unit 42 determines that it is the load charge and discharge mode, it proceeds to step S41. In Figure 2 In step S41 of Figure 2 the mode setting unit 43 sets the control of the controller 40 to the load charge and discharge mode. Next, in

[0068] In Figure 2 In step S42 of

[0069] the allowable current determination unit 44 determines the allowable current during charging and discharging of the battery 10.

[0070] In Figure 2In step S46, the charging and discharging of the battery 10 is started. During the charging and discharging, the current determination unit 47 may also perform the determination of whether the above-mentioned permissible current is below the threshold value Ith2. For example, the determination of the permissible current and the determination of whether the permissible current is below the threshold value Ith2 may be performed at predetermined time intervals. The closed state and the open state of the relays 21, 22, 31, 32 may also be appropriately switched according to the relationship between the permissible current and the threshold value Ith2. For example, the processing of the above-mentioned steps S42 to S46 may be repeated.

[0071] In the load charge and discharge mode, the allowable current will vary greatly depending on the driving conditions of the vehicle. Therefore, the magnitude relationship between the threshold value Ith2 and the allowable current will also change over time. The allowable current may be below the threshold value Ith2 at times, and may be greater than the threshold value Ith2 at times. If the allowable current changes from a state greater than the threshold value Ith2 to a state less than the threshold value Ith2, the indicator unit 45 may switch the relays 22 and 32 among the plurality of relays 21, 22, 31, and 32 to an open state. The storage unit 49 stores information that the relays 22 and 32 are switched to an open state. Then, if the allowable current changes from a state less than the threshold value Ith2 to a state greater than the threshold value Ith2, the indicator unit 45 may switch the relays 22 and 32 in the open state to a closed state. Then, if the allowable current changes from a state greater than the threshold value Ith2 to a state less than the threshold value Ith2 again, the indicator unit 45 may switch at least one of the plurality of relays 21, 22, 31, and 32 to an open state. The storage unit 49 stores information indicating that the relays 22 and 32 were switched from the closed state to the open state last time. The instruction unit 45 switches the relays 21 and 31 other than the relays 22 and 32 that were switched from the closed state to the open state last time to the open state.

[0072] As described above, the controller 40 may also switch the relay that was not switched from the closed state to the open state from the closed state to the open state preferentially when switching at least one of the plurality of relays 21, 22, 31, 32 from the closed state to the open state. By switching the relay that was not switched from the closed state to the open state preferentially from the closed state to the open state, the deviation of the time when the plurality of relays 21, 22, 31, 32 are in the closed state can be suppressed. As a result, it is difficult for the relays 21, 22, 31, 32 to be welded (a short circuit fault between the energized lines in the case of semiconductor relays) due to the heat generated by the charge and discharge current to occur.

[0073] When the use of the vehicle ends, the battery system 100 is shut down. When the battery system 100 is shut down, the instruction unit 45 may control the relays 21, 22, 31, 32 to be in an open state.

[0074] However, a mechanism that can ensure safety even in the case of relay welding can also be provided in the battery system.

[0075] <Battery system 100A>

[0076] Figure 4 is a schematic diagram showing the battery system 100A. In Figure 4 the components and parts that perform the same functions are appropriately marked with the same reference numerals, and repeated descriptions are appropriately omitted. As Figure 1 shown, the battery system 100A includes a battery 10, a first main relay 20, a second main relay 30, and a pyro-fuse 90. The pyro-fuse 90 is provided in the conduction path through which the battery 10 flows. The pyro-fuse 90 is a pyrotechnic current interrupter. The pyro-fuse 90 contains gunpowder and interrupts the conduction path by igniting the gunpowder. The pyro-fuse 90 is configured to receive a signal from the controller 40. In the present embodiment, the pyro-fuse 90 is provided on the connection line 11 that connects the two battery packs 10A1 and 10A2. Figure 4

[0077] The controller 40 includes a welding diagnostic unit 40a. The welding diagnostic unit 40a diagnoses whether at least one of the first main relay 20 and the second main relay 30 is welded. The welding diagnostic unit 40a can perform the diagnosis by detecting the current flowing through each of the relays 21, 22, 31, 32 or the voltage applied to each of the relays 21, 22, 31, 32. For example, when the relays 21, 22, 31, 32 are controlled to the open state, if the detected current or voltage is equal to or higher than the threshold value, it can be detected that the relay with the current or voltage equal to or higher than the threshold value is welded. If the welding diagnostic unit 40a detects that at least one of the first main relay 20 and the second main relay 30 is welded, it sends a cut-off signal to the pyro-fuse 90. The pyro-fuse 90 that receives the cut-off signal breaks the conduction path (the connection line 11 in the present embodiment).

[0078] There is a possibility that the first main relay 20 and the second main relay 30 may be thermally welded due to rapid charge and discharge, long-term use, etc. When any one of the parallel-connected relays 21, 22, relays 31, 32 is thermally welded, the resistance of the relay that is not thermally welded is low, and there is a possibility that the charge and discharge current may be biased. If the charge and discharge current is biased towards one relay, there is a concern that unexpected heating may occur in the relay through which a large amount of current flows.

[0079] In the above-described embodiment, if the welding diagnostic device 40a detects welding in at least any one of the first main relay 20 and the second main relay 30, the conductive path is broken by the explosive fuse 90. When the relay is welded, by breaking the conductive path with the explosive fuse 90, unexpected heating in the first main relay 20 and the second main relay 30 can be prevented. In addition, when one relay is provided for each of the first main relay 20 and the second main relay 30, unexpected heating can also be prevented.

[0080] In the above-described embodiment, the explosive fuse 90 is provided between the battery packs 10A1 and 10A2. Thus, when the relay is welded, the connection between the battery packs 10A1 and 10A2 is physically interrupted. Thereby, the safety of the operation during the inspection of the battery system 100A after the interruption of the path can be improved. In addition, the explosive fuse 90 does not have to be provided between the battery packs 10A1 and 10A2, and the explosive fuse 90 can also be provided in the conductive paths of the battery 10, the load 70, and the charger 80.

[0081] As described above, various explanations have been made for the technology disclosed herein. Unless otherwise specified, the embodiments listed herein do not limit the present invention. In addition, the technology disclosed herein can be variously modified, and as long as no special problems occur, each component or each process mentioned herein can be appropriately omitted or appropriately combined. In addition, this specification includes the disclosure described in the following items.

[0082] Item 1:

[0083] A battery system, wherein,

[0084] The above battery system includes:

[0085] A battery having a positive electrode and a negative electrode;

[0086] A first main relay serially connected to the positive electrode side of the above battery; and

[0087] A second main relay serially connected to the negative electrode side of the above battery,

[0088] At least any one of the above first main relay and the above second main relay includes a relay group in which a plurality of relays are connected in parallel,

[0089] The above plurality of relays are individually controlled to switch between a closed state and an open state.

[0090] Item 2:

[0091] The battery system according to Item 1, wherein,

[0092] The above battery system also includes a controller that controls the switching between the closed state and the open state of the above-mentioned multiple relays.

[0093] During rapid charge and discharge, the above controller switches the above-mentioned multiple relays to the closed state.

[0094] Item 3:

[0095] The battery system according to item 2, wherein

[0096] The above battery system further includes:

[0097] a voltage sensor that measures the voltage of the above battery; and a current sensor that measures the charge and discharge current flowing through the above battery.

[0098] During rapid charge and discharge, when the above voltage is equal to or higher than a predetermined value and the above charge and discharge current is equal to or lower than a predetermined value, the above controller switches at least one of the above-mentioned multiple relays to the open state.

[0099] Item 4:

[0100] The battery system according to any one of items 1 to 3, wherein

[0101] The above battery system further includes:

[0102] a controller that controls the switching between the closed state and the open state of the above-mentioned multiple relays; and

[0103] a current sensor that measures the charge and discharge current flowing through the above battery.

[0104] The above controller switches the closed state and the open state of the above-mentioned multiple relays included in the above relay group according to the allowable current.

[0105] Item 5:

[0106] The battery system according to any one of items 1 to 4, wherein

[0107] The above battery system also includes a controller that controls the switching between the closed state and the open state of the above-mentioned multiple relays.

[0108] When the above controller switches at least one of the above-mentioned multiple relays from the closed state to the open state, it preferentially switches the relay that was not switched from the closed state to the open state last time from the closed state to the open state.

[0109] Item 6:

[0110] The battery system according to any one of items 1 to 5, wherein

[0111] Both the first main relay and the second main relay described above include a relay group in which a plurality of relays are connected in parallel.

[0112] Item 7:

[0113] The battery system according to any one of Items 1 to 6, wherein

[0114] The battery system further includes an explosion fuse provided in a conduction path of a charge / discharge current flowing through the battery.

[0115] The controller includes a welding diagnostic unit that detects a situation in which at least one of the first main relay and the second main relay is welded.

[0116] If the welding diagnostic unit detects that at least one of the first main relay and the second main relay is welded, the conduction path is broken by the explosion fuse.

Claims

1. A battery system, wherein: The battery system has: A battery having a positive electrode and a negative electrode; a first main relay connected in series with the positive electrode side of the battery; and a second main relay connected in series with the negative electrode side of the battery, At least one of the first main relay and the second main relay includes a relay group including a plurality of relays connected in parallel. The switching between the closed state and the open state of the plurality of relays is controlled individually.

2. The battery system according to claim 1, wherein: The battery system further includes a controller, which controls the switching between the closed state and the open state of the plurality of relays. During rapid charging and discharging, the controller switches the plurality of relays to a closed state.

3. The battery system according to claim 2, wherein: The battery system also includes: a voltage sensor for measuring a voltage of the battery; and a current sensor for measuring a charge and discharge current flowing in the battery, During rapid charge and discharge, when the voltage is equal to or higher than a predetermined value and the charge and discharge current is equal to or lower than a predetermined value, the controller switches at least one of the plurality of relays to an open state.

4. The battery system according to any one of claims 1 to 3, wherein: The battery system also includes: A controller that controls switching between a closed state and an open state of the plurality of relays; and a current sensor for measuring a charge and discharge current flowing in the battery, The controller switches the plurality of relays included in the relay group between a closed state and an open state according to an allowable current.

5. The battery system according to any one of claims 1 to 3, wherein: The battery system further includes a controller, which controls the switching between the closed state and the open state of the plurality of relays. When the controller switches at least one of the plurality of relays from a closed state to an open state, the controller preferentially switches a relay that was not switched from a closed state to an open state last time from a closed state to an open state.

6. The battery system according to any one of claims 1 to 3, wherein: The first main relay and the second main relay both include a relay group in which a plurality of relays are connected in parallel.

7. The battery system according to any one of claims 1 to 3, wherein: The battery system further comprises an explosive fuse provided in a conductive path of a charge and discharge current flowing in the battery. The controller includes a welding diagnostic device for detecting a welding condition of at least one of the first main relay and the second main relay. When the welding diagnostic device detects that at least one of the first main relay and the second main relay is welded, the conductive path is broken by the exploding fuse.

Images