Cell system

Abstract

To control fluctuation in current consumption in each battery module.SOLUTION: A battery system 1 includes a pair of output terminals 5 to be connected to a load 100, a plurality of battery modules 10 to be connected to the output terminals 5 and arranged in parallel, and a control device 60. The battery module 10 includes a battery unit 12 having single cells 11 connected in series, a main relay 20 provided at a first-side end portion of the battery unit 12, a unit relay 30 provided at a second-side end portion of the battery unit 12, and a pre-charge unit 40 provided in parallel to the main relay 20. The control device 60 includes a pre-charge processing execution unit 67. When the plurality of battery modules 10 is connected to the load 100, the control device 60 controls the plurality of battery modules 10 such that pre-charge processing is executed on each battery module 10 of the plurality of battery modules 10 one by one, and then the plurality of battery modules 10 is connected to the pair of output terminals 5.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] For example, Patent Document 1 discloses a power supply device equipped with a plurality of battery units connected in parallel. The battery unit has a plurality of battery blocks connected in series. Each battery unit is provided with a pre-connection circuit having a current limiting resistor and an equalization switch connected in series to the current limiting resistor. When the power supply device is connected to a load, the remaining capacity of the battery units is equalized by passing a current through the pre-connection circuit connected to each battery unit.

[0003] For example, Patent Document 2 discloses a method for adjusting the voltage of a battery pack in which a plurality of modules, each of which has a plurality of cells connected in series, are connected in parallel. A resistor is connected in series to each module. Since a plurality of modules are connected in parallel in this manner, a current flows from a module with a large remaining capacity to a module with a small remaining capacity, and the remaining capacities of the modules gradually become equal, allowing the voltage to be adjusted.

[0004] For example, Patent Document 3 discloses a turn-on operation control device in which multiple battery packs are connected in parallel. Each battery pack is provided with multiple battery cells connected in series and a switch unit directly connected to the multiple battery cells. Here, before charging or discharging is started, an integrated watt energy value in each battery pack is calculated, and the turn-on order of the switch units in the multiple battery packs is determined so that the integrated watt energy values ​​are in descending order. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 043723 [Patent Document 2] JP 2005-151679 A [Patent Document 3] Patent No. 7136424 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in the power supply device disclosed in Patent Document 1, for example, when current is passed through the pre-connection circuit for multiple battery units, the fluctuation in current consumption of the control device that controls the equalization switch and the like may become large. If the fluctuation in current consumption is large, it is considered that a load is placed on the power supply that supplies power to the control device, causing the voltage to fluctuate, and the operation of the power supply device may become unstable. Therefore, it is preferable to suppress the fluctuation in current consumption as much as possible. [Means for solving the problem]

[0007] The battery system disclosed herein includes a pair of output terminals connected to a load, a plurality of battery modules connected to the pair of output terminals and arranged in parallel, and a control device. The plurality of battery modules each include a battery unit having a plurality of single cells connected in series, a main relay provided at a first end of the battery unit, a unit relay provided at a second end of the battery unit, and a precharge unit provided in parallel to the main relay. The precharge unit includes a pre-resistor and a precharge relay connected in series to the pre-resistor. The control device includes a precharge process execution unit that controls the plurality of battery modules to be connected to the pair of output terminals after performing a precharge process on each of the plurality of battery modules when the plurality of battery modules are connected to the load through the pair of output terminals. The precharge process is a process in which, for the one target battery module, after turning off the main relay and turning on the unit relay and the precharge relay, if the difference between the main voltage acting across the pair of output terminals and the unit voltage of the battery unit in the one battery module is equal to or less than a predetermined threshold, the main relay of the one battery module is turned on and the precharge relay is turned off.

[0008] If the precharge relays are turned on simultaneously for a plurality of battery modules, the current consumption required to control the precharge relays temporarily increases, and as a result, the fluctuation in the current consumption of the control device that controls the precharge relays increases. If the fluctuation in the current consumption of the control device increases in this way, for example, a load may be applied to the power source that supplies power to the control device, causing the voltage to fluctuate. If the voltage fluctuation of the control device increases in this way, the operation of the power supply system may become unstable. However, according to the battery system described above, the precharge process is sequentially performed on one battery module out of the plurality of battery modules. Therefore, the precharge relays are not turned on simultaneously for a plurality of battery modules, and the timing at which the current consumption of each battery module increases can be dispersed. As a result, the fluctuation in the overall current consumption in the control device can be suppressed, and the operation of the battery system can be made less likely to become unstable. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a battery system according to an embodiment; [Diagram 2] 10 is a flowchart showing a procedure for executing a precharge process on the first to third battery modules. [Diagram 3] 10 is a timing chart showing a procedure for executing a precharge process on the first to third battery modules. [Figure 4] FIG. 11 is a diagram showing the transition of the voltage over time in each battery module when the first to third battery modules are simultaneously subjected to a precharge process. [Diagram 5] FIG. 11 is a diagram showing the transition of the voltage over time in each battery module when the precharge process is executed on the first to third battery modules in order. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. Note that the embodiment described herein is, of course, not intended to limit the present invention in particular. Each figure is a schematic diagram and does not necessarily faithfully reflect an actual product. Furthermore, the same reference numerals are appropriately used for members and parts that perform the same function, and duplicated explanations are appropriately omitted.

[0011] FIG. 1 is a schematic diagram showing a battery system 1 according to the present embodiment. As shown in FIG. 1, the battery system 1 is connected to a load 100. The load 100 is not particularly limited, but may be, for example, a drive device such as an electric motor of a vehicle, or an inverter. A smoothing capacitor for reducing abrupt changes in current may be connected to the load 100. Here, the battery system 1 is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, and is used as a power source for supplying power to an electric motor that drives the vehicle. However, the battery system 1 is not limited to use in a vehicle.

[0012] The battery system 1 includes a pair of output terminals 5, a plurality of battery modules 10, and a control device 60. The pair of output terminals 5 are connected to a load 100. Here, one of the pair of output terminals 5 is a positive terminal, and the other output terminal 5 is a negative terminal.

[0013] The battery modules 10 are connected to a pair of output terminals 5. In this embodiment, the battery modules 10 are connected to a main bus 8, and a pair of output terminals 5 is connected to the main bus 8. Therefore, the battery modules 10 are connected to the pair of output terminals 5 via the main bus 8. The battery modules 10 are indirectly connected to a load 100 via the pair of output terminals 5. The load 100 can convert the power of the battery modules 10 into motive power or supply regenerative power to the battery modules 10. The battery modules 10 are arranged (in other words, connected) in parallel. The number of battery modules 10 is not particularly limited, but is three in this embodiment. Here, the three battery modules 10 are appropriately referred to as a first battery module 10A, a second battery module 10B, and a third battery module 10C. The battery module 10 has a first battery module 10A, a second battery module 10B, and a third battery module 10C. In the following description, when the first battery module 10A to the third battery module 10C are commonly described, the term battery module 10 will be used.

[0014] In this embodiment, the first battery module 10A to the third battery module 10C have the same configuration. One battery module 10 includes a plurality of single cells 11, a main relay 20, a unit relay 30, a precharge unit 40, and a battery control device 50. The single cells 11 are chargeable and dischargeable. For example, a secondary battery that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (for example, a positive electrode and a negative electrode) via an electrolyte may be used as the single cell 11. For example, a lithium ion secondary battery or a nickel-hydrogen battery may be used as the single cell 11. The multiple single cells 11 are connected in series. Here, the multiple single cells 11 are connected in series via a bus bar (not shown). The number of single cells 11 in one battery module 10 is not particularly limited and is a predetermined number. In this embodiment, the number of single cells 11 in one battery module 10 is five. The numbers of single cells 11 in the first battery module 10A to the third battery module 10C are the same, but may be different. Here, the plurality of unit cells 11 connected in series is referred to as a battery unit 12. The battery unit 12 has the plurality of unit cells 11 connected in series.

[0015] The main relay 20 is connected in series to the multiple cells 11 (in other words, the battery unit 12). Here, the main relay 20 is provided at a first end of the battery unit 12. Here, the "first end" refers to the positive end of the battery unit 12 (in other words, the multiple cells 11). However, the first end may also refer to the negative end of the battery unit 12. In other words, the main relay 20 may be provided at the negative end of the battery unit 12. The main relay 20 is a relay that switches the connection between the first end of the battery unit 12 and the load 100 between ON and OFF.

[0016] In this embodiment, turning the relay ON refers to a connected state (e.g., a closed state), and turning the relay OFF refers to a disconnected state (e.g., an open state).

[0017] The unit relay 30 is connected in series to the plurality of single cells 11 (in other words, the battery unit 12). Here, the unit relay 30 is provided at the second end of the battery unit 12. The "second end" refers to the end opposite to the first end of the battery unit 12 (in other words, the plurality of single cells 11). Here, the "second end" refers to the negative end of the battery unit 12. However, the second end may also refer to the positive end of the battery unit 12. In other words, the unit relay 30 may be provided at the positive end of the battery unit 12. The unit relay 30 is a relay that switches ON and OFF the connection between the second end of the battery unit 12 and the load 100.

[0018] The precharge unit 40 is provided in parallel to the main relay 20. In other words, the precharge unit 40 is connected in parallel to the main relay 20. Here, the precharge unit 40 is provided at a first end (here, the positive end) of the battery unit 12 (for example, a plurality of single cells 11 connected in series). The precharge unit 40 is a circuit that suppresses an inrush current from flowing to the load 100 when power is supplied from the battery system 1 to the load 100. The configuration of the precharge unit 40 is not particularly limited. Here, the precharge unit 40 includes a pre-resistor 41 and a precharge relay 42 connected in series to the pre-resistor 41. The precharge relay 42 can be switched between ON and OFF connection.

[0019] The battery control device 50 is connected to the plurality of single cells 11. The battery control device 50 is configured with a board and is provided with a so-called register. The battery control device 50 may be configured with, for example, a microcontroller. The battery control device 50 has a single cell voltage detector 51, an equalizer 52, and a battery unit voltage detector 53.

[0020] The cell voltage detector 51 detects the cell voltage of each of the multiple cells 11 that make up the battery unit 12. The cell voltage detector 51 is realized, for example, by a circuit that can detect the voltage of each of the multiple cells 11. The cell voltage detector 51 may have, for example, multiple connection terminals that are connected to the positive and negative electrodes of each of the cells 11 that make up the battery unit 12.

[0021] The equalizer 52 equalizes the remaining capacity of the plurality of single cells 11 constituting the battery unit 12 based on the single cell voltages of the single cells 11 detected by the single cell voltage detector 51. The specific configuration of the equalizer 52 is not particularly limited as long as it can equalize the remaining capacity of the plurality of single cells 11. The equalizer 52 is realized by a so-called equalization circuit. Although not shown, the equalizer 52 may be realized by, for example, a plurality of discharge circuits connected between a plurality of connection terminals connected to the positive and negative electrodes of the single cells 11, and a control circuit. Each of the plurality of discharge circuits includes a discharge resistor and a switching element. The control circuit is configured to be able to acquire the single cell voltage of each of the plurality of single cells 11 from the single cell voltage detector 51. The control circuit acquires the single cell voltage of each of the plurality of single cells 11 from the single cell voltage detector 51 via, for example, a multiplexer not shown. The control circuit is configured to switch the switching element ON and OFF based on the acquired cell voltage, and to execute a process of appropriately discharging the cell voltage of the higher voltage cell 11 so as to match that of the lower voltage cell 11.

[0022] The battery unit voltage detector 53 detects the unit voltage of the multiple cells 11 (in other words, the battery unit 12) connected in series. The battery unit voltage detector 53 is realized, for example, by a circuit capable of detecting the unit voltage of the battery unit 12. The battery unit voltage detector 53 has multiple connection terminals connected to the positive and negative electrodes of the multiple cells 11 that constitute the battery unit 12. The battery unit voltage detector 53 may detect the unit voltage of the battery unit 12 by, for example, summing up the cell voltages of the individual cells 11 detected by the cell voltage detector 51.

[0023] The control device 60 is configured by, for example, a microcontroller. The control device 60 includes a communication interface, a central processing unit (CPU) that executes instructions of a control program, a read only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) that is used as a working area for expanding the program, and a storage device such as a memory that stores the program and various data. The control device 60 is electrically connected to the main relays 20, unit relays 30, and precharge relays 42 of the precharge unit 40 of the multiple battery modules 10 (here, the first battery module 10A to the third battery module 10C), and the battery control device 50. The control device 60 controls the switching between ON and OFF of the main relays 20, unit relays 30, and precharge relays 42 for each battery module 10. In this embodiment, as shown in FIG. 1, a power source 70 is connected to the control device 60. Power is supplied to the control device 60 from the power source 70.

[0024] 1, the control device 60 includes a main voltage acquiring section 61, a unit voltage acquiring section 63, an order determining section 65, a precharge processing executing section 67, and a storage section 69. The main voltage acquiring section 61, the unit voltage acquiring section 63, the order determining section 65, the precharge processing executing section 67, and the storage section 69 may be realized by one or more processors, or may be realized by a circuit.

[0025] The main voltage acquiring unit 61 acquires the overall main voltage of the multiple battery modules 10 connected in parallel. In other words, the main voltage acquiring unit 61 acquires the main voltage acting between a pair of output terminals 5. In further other words, the main voltage acquiring unit 61 acquires the main voltage between the main buses 8. Note that the configuration of the main voltage acquiring unit 61 is not particularly limited as long as it is possible to acquire the main voltage. For example, the main voltage acquiring unit 61 may be realized by a circuit capable of detecting the main voltage between the pair of output terminals 5. The main voltage acquiring unit 61 may be provided with connection terminals connected to, for example, the positive main bus 8 and the negative main bus 8 (or the pair of output terminals 5).

[0026] The unit voltage acquiring unit 63 acquires the unit voltage of the battery unit 12 for each of the multiple battery modules 10. Here, the unit voltage acquiring unit 63 acquires the unit voltages of the first battery module 10A to the third battery module 10C. In this embodiment, the unit voltage acquiring unit 63 acquires the unit voltage from the battery unit voltage detector 53 of the battery control device 50 of each battery module 10. Here, the battery unit voltage detector 53 detects the unit voltage of the battery unit 12 and transmits the detected unit voltage to the control device 60. The unit voltage acquiring unit 63 receives the unit voltage transmitted from the battery unit voltage detector 53 to acquire the unit voltage.

[0027] When the battery modules 10 are connected to the load 100 through a pair of output terminals 5, the precharge process execution unit 67 executes the precharge process for each of the battery modules 10. The precharge process execution unit 67 executes the precharge process for each of the battery modules 10. In this embodiment, the precharge process execution unit 67 executes the precharge process for the first battery module 10A, the second battery module 10B, and the third battery module 10C independently. For example, the precharge process execution unit 67 executes the precharge process for the first battery module 10A, and after the precharge process for the first battery module 10A is completed, the precharge process execution unit 67 executes the precharge process for the second battery module 10B. Then, after the precharge process for the second battery module 10B is completed, the precharge process execution unit 67 executes the precharge process for the third battery module 10C.

[0028] Here, the pre-charge process is a process for suppressing an inrush current from flowing to the load 100 by controlling a current to flow to the pre-charge unit 40 when the battery unit 12 of the battery module 10 is connected to the load 100 through a pair of output terminals 5. In the pre-charge process, a current is actively passed to the pre-charge unit 40 without passing a current to the main relay 20, thereby suppressing an inrush current from flowing to the load 100. In this embodiment, the pre-charge process is performed by turning off the main relay 20 for the target battery module 10 and turning on the unit relay 30 and the pre-charge relay 42, and then detecting whether the difference between the main voltage acting between the pair of output terminals 5 and the unit voltage of the battery unit 12 in one battery module 10 reaches a predetermined threshold value V thIn the following cases (see FIG. 2), the main relay 20 of one battery module 10 is turned ON and the pre-charge relay 42 is turned OFF. Here, the pre-charge process is performed when the main relay 20, the unit relay 30, and the pre-charge relay 42 are in the OFF state, the unit relay 30 is turned ON, and then the pre-charge relay 42 is turned ON until the difference between the main voltage and the unit voltage reaches the threshold value V th After the voltage drops below this level, the main relay 20 is turned ON and the pre-charge relay 42 is turned OFF.

[0029] The order determination unit 65 determines the order in which the precharge process is to be performed on the multiple battery modules 10 when the precharge process is performed by the precharge process execution unit 67. Here, the order determination unit 65 determines the order in which the precharge process is to be performed based on the unit voltage of each battery module 10. Here, the order determination unit 65 arranges the unit voltages of the multiple battery modules 10 acquired by the unit voltage acquisition unit 63 in descending order, and determines to perform the precharge process on the multiple battery modules 10 in the arranged order. The precharge process execution unit 67 performs the precharge process on the multiple battery modules 10 in the order determined by the order determination unit 65.

[0030] Next, a procedure for executing the precharge process on the first battery module 10A to the third battery module 10C will be described with reference to the flowchart of FIG. us In this case, s=1, 2, 3 are substituted in order. Therefore, the unit voltage V us is the unit voltage V u1 , V u2 , V u3 Fig. 3 is a timing chart showing the procedure for executing the precharge process on the first battery module 10A to the third battery module 10C. Here, before the flowchart in Fig. 2 starts, the main relays 20, unit relays 30 and precharge relays 42 in the first battery module 10A to the third battery module 10C are in the OFF state, as shown at time t0 in Fig. 3.

[0031] First, in step S101 of FIG. 2, the unit voltage acquisition unit 63 of FIG. 1 acquires the unit voltage V u1 , the unit voltage V of the second battery module 10B u2 , the unit voltage V of the third battery module 10C u3 Here, the unit voltage acquisition unit 63 acquires the unit voltage V from the battery unit voltage detectors 53 of the first battery module 10A to the third battery module 10C. u1 , V u2 , V u3 The unit voltage V acquired by the unit voltage acquisition unit 63 is acquired. u1 , V u2 , V u3 is stored in the storage unit 69 (see FIG. 1).

[0032] Next, in step S103 in FIG. 2, the order determination unit 65 in FIG. 1 determines the order in which the precharge process is to be performed on the first battery module 10A to the third battery module 10C. Here, the order determination unit 65 determines the order in which the precharge process is to be performed on the first battery module 10A to the third battery module 10C based on the unit voltage V u1 , V u2 , V u3 Based on the unit voltage V u1 , V u2 , V u3 In the present embodiment, the unit voltages V u1 , V u2 , V u3 In this case, the unit voltage V u1 , V u2 , V u3 In descending order, the precharge process is executed in the order of the first battery module 10A, the second battery module 10B, and the third battery module 10C.

[0033] Next, the precharge process is performed for the first battery module 10A by sequentially executing steps S105 to S117 in FIG. 2. As shown in FIG. 2, the precharge process execution unit 67 in FIG. 1 first turns on the unit relay 30 in step S105 for the first battery module 10A, and then turns on the precharge relay 42 in step S107. In FIG. 3, for the first battery module 10A, the unit relay 30 is turned on at time t11, and the precharge relay 42 is turned on at time t12. Note that the order of the processes in steps S105 and S107 may be reversed, and the unit relay 30 may be turned on after the precharge relay 42 is turned on. At time t12, the unit relay 30 and the precharge relay 42 are turned on, so that a current flows through the precharge unit 40, thereby increasing the unit voltage V u1 gradually becomes higher.

[0034] After that, as shown in FIG. 2, in step S109, the main voltage acquisition unit 61 in FIG. 1 acquires the main voltage V um In step S111, the unit voltage acquisition unit 63 in FIG. 1 acquires the unit voltage V u1 Then, in step S113 of FIG. 2, the precharge process execution unit 67 of FIG. 1 acquires the main voltage V um and unit voltage V u1 (here, |V um -V u1 |) is the threshold V th Here, it is determined whether the main voltage V um and unit voltage V u1 The difference between this and the threshold V th If it is greater than the main voltage V um and unit voltage V u1 The difference between this and the threshold V th In the following cases, the process proceeds to step S115.

[0035] The pre-charge process execution unit 67 in Fig. 1 turns ON the main relay 20 for the first battery module 10A in step S115, and turns OFF the pre-charge relay 42 in step S117. In Fig. 3, for the first battery module 10A, the main relay 20 is turned ON at time t13, and the pre-charge relay 42 is turned OFF at time t14. Here, the pre-charge process for the first battery module 10A is executed from time t11 to time t14.

[0036] After the precharge process is performed on the first battery module 10A in this manner, the precharge process is performed on the second battery module 10B by sequentially performing steps S105 to S117 in FIG. 2. Here, after the precharge process on the first battery module 10A is completed (after time t14 in FIG. 3), the precharge process execution unit 67 in FIG. 1 executes the precharge process on the second battery module 10B in the state where the precharge relay 42 is OFF and the main relay 20 and the unit relay 30 are ON in the first battery module 10A. Note that the processes of steps S105 to S117 on the second battery module 10B are substantially the same as those for the first battery module 10A, and therefore will not be described. In FIG. 3, the unit relay 30 is turned ON at time t21, which is later than time t14, and the precharge relay 42 is turned ON at time t22 for the second battery module 10B. After that, from time t22 to time t23, the unit voltage V u2 At time t23, the main voltage V um and unit voltage V u2 The difference between this and the threshold V th As a result, the main relay 20 turns ON at time t23, and the pre-charge relay 42 turns OFF at time t24. Here, the pre-charge process for the second battery module 10B is executed between time t21 and time t24.

[0037] After the precharge process is performed on the first battery module 10A and the second battery module 10B, the precharge process is performed on the third battery module 10C by sequentially performing steps S105 to S117 in FIG. 2. Here, the precharge process execution unit 67 in FIG. 1 executes the precharge process on the third battery module 10C in a state in which the precharge relay 42 is OFF and the main relay 20 and the unit relay 30 are ON in the first battery module 10A and the second battery module 10B. Note that the processes in steps S105 to S117 for the third battery module 10C are substantially the same as those in the first battery module 10A, and therefore will not be described here. In FIG. 3, for the third battery module 10C, the unit relay 30 is turned ON at time t31, which is later than time t24, and the precharge relay 42 is turned ON at time t32. After that, from time t32 to time t33, the unit voltage V u3 At time t33, the main voltage V um and unit voltage V u3 The difference between this and the threshold V th As a result, the main relay 20 turns ON at time t33, and the precharge relay 42 turns OFF at time t34. Here, the precharge process for the third battery module 10C is executed between time t31 and time t34. In this way, the first battery module 10A, the second battery module 10B, and the third battery module 10C are precharged independently in order, and the flow chart in FIG. 2 ends.

[0038] As described above, in this embodiment, as shown in FIG. 1, the battery system 1 includes a pair of output terminals 5 connected to the load 100, a plurality of battery modules 10 connected to the pair of output terminals 5 and arranged in parallel, and a control device 60. Each of the battery modules 10 includes a battery unit 12 having a plurality of single cells 11 connected in series, a main relay 20 provided at a first end (here, the positive end) of the battery unit 12, a unit relay 30 provided at a second end (here, the negative end) of the battery unit 12, and a pre-charge unit 40 provided in parallel to the main relay 20. The pre-charge unit 40 includes a pre-resistor 41 and a pre-charge relay 42 connected in series to the pre-resistor 41. The control device 60 includes a pre-charge process execution unit 67 that controls the battery modules 10 to be connected to the pair of output terminals 5 after performing a pre-charge process on each of the battery modules 10 when the battery modules 10 are connected to the load 100 through the pair of output terminals 5. In the pre-charge process, the main relay 20 is turned OFF and the unit relay 30 and the pre-charge relay 42 are turned ON for one of the target battery modules 10. Then, the difference between the main voltage acting between the pair of output terminals 5 and the unit voltage of the battery unit 12 in one of the battery modules 10 is checked to see if it exceeds a predetermined threshold value V th (See FIG. 2) In the following cases, the main relay 20 of one battery module 10 is turned ON and the pre-charge relay 42 is turned OFF.

[0039] If the precharge relays 42 are turned ON simultaneously for a plurality of battery modules 10, the current consumption required to control the precharge relays 42 temporarily increases, and as a result, the fluctuation in the current consumption of the control device 60 that controls the precharge relays 42 increases. If the fluctuation in the current consumption increases in this way, a load may be applied to the power source 70 (see FIG. 1) that supplies the control device 60, causing the voltage to fluctuate. If the voltage fluctuation for the control device 60 increases in this way, the operation of the battery system 1 may become unstable. However, in this embodiment, the precharge process is sequentially performed for one battery module 10 out of the plurality of battery modules 10. Therefore, the precharge relays 42 are not turned ON simultaneously for a plurality of battery modules 10, and the timing at which the current consumption for each battery module 10 increases can be dispersed. As a result, the fluctuation in the overall current consumption in the control device 60 can be suppressed, and the operation of the battery system 1 can be made less likely to become unstable.

[0040] FIG. 4 is a diagram showing the transition of voltage over time in each of the battery modules 10A, 10B, and 10C when the first battery module 10A to the third battery module 10C are simultaneously precharged and the precharge relay 42 is simultaneously turned ON. FIG. 5 is a diagram showing the transition of voltage over time in each of the battery modules 10A, 10B, and 10C when the first battery module 10A to the third battery module 10C are sequentially precharged. In FIGS. 4 and 5, the horizontal axis indicates time and the vertical axis indicates voltage. As shown in FIG. 4, if the first battery module 10A to the third battery module 10C are simultaneously precharged and the precharge relay 42 is simultaneously turned ON, the voltages of the battery modules 10 are equalized at time t101. On the other hand, as shown in Fig. 5, in the present embodiment, when the precharge process is performed on the first battery module 10A to the third battery module 10C in sequence and the precharge relays 42 are not simultaneously turned ON, the voltages of the battery modules 10A, 10B, and 10C can be equalized at time t100, which is before time t101. Therefore, in the present embodiment, the precharge process is performed on one battery module 10 out of the multiple battery modules 10 in sequence, so that the voltages of the battery modules 10 can be equalized in a short time. In this way, in the present embodiment, the voltages of the battery modules 10 can be equalized in a short time, so that the battery system 1 can be started up quickly.

[0041] In this embodiment, as shown in FIG. 3, in the pre-charge process, the main relay 20, the unit relay 30, and the pre-charge relay 42 are in the OFF state, and then the unit relay 30 is turned ON, and the difference between the main voltage and the unit voltage reaches the threshold value V thAfter the load 100 is discharged, the main relay 20 is turned ON and then the pre-charge relay 42 is turned OFF. In this manner, in the pre-charge process, by turning the main relay 20 ON and then turning the pre-charge relay 42 OFF, the battery module 10 can be kept in a state where it is always connected to the load 100, and therefore, it is possible to prevent the battery module 10 from being disconnected.

[0042] In this embodiment, as shown in Fig. 1, the battery modules 10 include a first battery module 10A, a second battery module 10B, and a third battery module 10C. As shown in Fig. 3, the precharge process execution unit 67 in Fig. 1 executes a precharge process on the first battery module 10A, and after the precharge process on the first battery module 10A is completed, executes a precharge process on the second battery module 10B. Then, after the precharge process on the second battery module 10B is completed, the precharge process execution unit 67 executes a precharge process on the third battery module 10C. This makes it possible to reliably execute the precharge processes on the first battery module 10A to the third battery module 10C independently.

[0043] In this embodiment, the precharge process execution unit 67 in Fig. 1 executes the precharge process for the second battery module 10B after the precharge process for the first battery module 10A is completed (after time t14 in Fig. 3) in a state where the precharge relay 42 is OFF and the main relay 20 and the unit relay 30 are ON in the first battery module 10A. In addition, the precharge process execution unit 67 executes the precharge process for the third battery module 10C after the precharge process for the second battery module 10B is completed (after time t24 in Fig. 3) in a state where the precharge relay 42 is OFF and the main relay 20 and the unit relay 30 are ON in both the first battery module 10A and the second battery module 10B. This ensures that the battery module 10 is connected to the load 100 after the precharge process is completed.

[0044] In this embodiment, as shown in FIG. 1, the control device 60 includes a unit voltage acquisition unit 63 and an order determination unit 65. In step S101 of FIG. 2, the unit voltage acquisition unit 63 acquires the unit voltage of the battery unit 12 for each of the plurality of battery modules 10. In step S103 of FIG. 2, the order determination unit 65 arranges the unit voltages of the plurality of battery modules 10 acquired by the unit voltage acquisition unit 63 in descending order, and determines to execute the precharge process for the plurality of battery modules 10 in the arranged order. The precharge process execution unit 67 of FIG. 1 executes the precharge process for the plurality of battery modules 10 in the order determined by the order determination unit 65. In this way, by executing the precharge process for the plurality of battery modules 10 in the order in which the unit voltages are descending, the potential difference between the main voltage and the unit voltage between the plurality of battery modules 10 can be reduced. Therefore, it is possible to suppress an overcurrent that may occur due to the precharge process.

[0045] The order determination unit 65 may arrange the unit voltages of the multiple battery modules 10 in ascending order and determine to execute the precharge process on the multiple battery modules 10 in the arranged order. Even in this case, the potential difference between the main voltage and the unit voltage among the multiple battery modules 10 can be reduced, thereby suppressing the occurrence of overcurrent.

[0046] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component or each process described herein can be omitted or combined as appropriate, unless a particular problem occurs.

[0047] As described above, this specification includes the disclosures set forth in the following sections. Section 1: A pair of output terminals connected to a load; a plurality of battery modules connected to the pair of output terminals and arranged in parallel; A control device; Equipped with The plurality of battery modules include a battery unit having a plurality of unit cells connected in series; a main relay provided at a first end of the battery unit; a unit relay provided at an end of the second side of the battery unit; a precharge unit provided in parallel with the main relay; Each of them has The precharge unit includes: Pre-resistor, A precharge relay connected in series to the pre-resistor; Equipped with the control device includes a precharge process execution unit that, when the plurality of battery modules are connected to the load through the pair of output terminals, performs a precharge process on each of the plurality of battery modules one by one, and then controls the plurality of battery modules to be connected to the pair of output terminals; The pre-charge process is a process of turning on the main relay of the one battery module in question and turning on the pre-charge relay when a difference between the main voltage acting across the pair of output terminals and the unit voltage of the battery unit in the one battery module is equal to or less than a predetermined threshold after turning off the main relay and turning on the unit relay and the pre-charge relay for the one battery module in question.

[0048] Section 2: Item 2. The battery system according to item 1, wherein in the precharge process, while the main relay, the unit relay, and the precharge relay are in an OFF state, the unit relay is turned ON, and then the precharge relay is turned ON; and after a difference between the main voltage and the unit voltage becomes equal to or less than the threshold, the main relay is turned ON, and then the precharge relay is turned OFF.

[0049] Section 3: The plurality of battery modules include a first battery module and a second battery module, The battery system described in item 1 or 2, wherein the precharge process execution unit executes the precharge process on the first battery module, and after the precharge process on the first battery module is completed, executes the precharge process on the second battery module.

[0050] Section 4: 4. The battery system described in item 3, wherein after the precharge process for the first battery module is completed, the precharge process execution unit executes the precharge process for the second battery module in a state in which the precharge relay is OFF and the main relay and the unit relay are ON in the first battery module.

[0051] Section 5: The control device includes: a unit voltage acquisition unit that acquires the unit voltage of the battery unit for each of the plurality of battery modules; an order determination unit that arranges the unit voltages of the plurality of battery modules acquired by the unit voltage acquisition unit in ascending or descending order and determines to execute the precharge process on the plurality of battery modules in the arranged order; Equipped with 5. The battery system according to any one of items 1 to 4, wherein the precharge process execution unit sequentially executes the precharge process on the plurality of battery modules in the order determined by the order determination unit. [Explanation of symbols]

[0052] 1 Battery System 5 Pair of Output Terminals 10 Battery module 10A 1st Battery Module 10B Second battery module 10C 3rd battery module 11 Battery 12 Battery unit 20 Main Relay 30 Unit Relay 40 Precharge Unit 41 Pre-resistor 42 Precharge relay 60 Control device 61 Main voltage acquisition section 63 Unit voltage acquisition section 65 Order Determination Section 67 Precharge processing execution unit

Claims

1. A pair of output terminals connected to a load; a plurality of battery modules connected to the pair of output terminals and arranged in parallel; A control device; Equipped with The plurality of battery modules include a battery unit having a plurality of unit cells connected in series; a main relay provided at a first end of the battery unit; a unit relay provided at an end of the second side of the battery unit; a precharge unit provided in parallel with the main relay; Each of them has The precharge unit includes: Pre-resistor, A precharge relay connected in series to the pre-resistor; Equipped with the control device includes a precharge process execution unit that performs a precharge process on each of the battery modules one by one when the battery modules are connected to the load through the pair of output terminals, and then controls the battery modules to be connected to the pair of output terminals; The pre-charge process is a process of turning ON the main relay of the one battery module of interest and turning OFF the pre-charge relay when a difference between the main voltage acting across the pair of output terminals and the unit voltage of the battery unit in the one battery module is equal to or less than a predetermined threshold after turning OFF the main relay and turning ON the unit relay and the pre-charge relay for the one battery module of interest.

2. 2. The battery system according to claim 1, wherein in the precharge process, while the main relay, the unit relay and the precharge relay are in an OFF state, the unit relay is turned ON, and then the precharge relay is turned ON; and after a difference between the main voltage and the unit voltage becomes equal to or less than the threshold value, the main relay is turned ON, and then the precharge relay is turned OFF.

3. The plurality of battery modules include a first battery module and a second battery module, 2. The battery system according to claim 1, wherein the precharge process execution unit executes the precharge process on the first battery module, and after the precharge process on the first battery module is completed, executes the precharge process on the second battery module.

4. 4. The battery system according to claim 3, wherein after the precharge process for the first battery module is completed, the precharge process execution unit executes the precharge process for the second battery module in a state in which the precharge relay is OFF and the main relay and the unit relay are ON in the first battery module.

5. The control device includes: a unit voltage acquisition unit that acquires the unit voltage of the battery unit for each of the plurality of battery modules; an order determination unit that arranges the unit voltages of the plurality of battery modules acquired by the unit voltage acquisition unit in ascending or descending order and determines to execute the precharge process on the plurality of battery modules in the arranged order; Equipped with 5. The battery system according to claim 1, wherein the precharge process execution unit sequentially executes the precharge process on the plurality of battery modules in the order determined by the order determination unit.

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