Battery system

Abstract

This suppresses uneven degradation of the pre-resistor. [Solution] The battery system 1 comprises a plurality of battery modules 10 connected to a load 100 and a control device 60. Each battery module 10 includes a precharge unit 40 having a pre-resistor 41. The control device 60 includes a pre-charge processing execution unit 67 that performs pre-charge processing on one battery module 10 at a time from the plurality of battery modules 10. The control device 60 sets a cooling time T which is the elapsed time since the previous pre-charge processing of the battery module that was ranked first in the previous connection to the load 100 and was the first to have pre-charge processing performed on. C A time acquisition unit 64 acquires the time, and a cooling time T C The predetermined reference time T D The system further includes a sequence determination unit 65 that determines the order such that, in the following cases, the pre-charge process is not performed first on the battery module that was ranked first in the previous sequence.

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a battery system for supplying power to an external load. This battery system comprises multiple battery modules, each of which includes a precharge unit with a preresistor. The battery system is configured to perform a precharge process in which current flows from the battery module to the load via the preresistor when each battery module is connected to a load. This prevents inrush current exceeding the rated current from flowing to the load. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-170768 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, in the battery system described in Patent Document 1, the pre-resistor of a specific battery module sometimes deteriorated among multiple battery modules. The technology disclosed herein aims to suppress such uneven deterioration of pre-resistors. [Means for solving the problem]

[0005] The battery system disclosed herein comprises 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 comprises a battery unit having a plurality of single cells connected in series, a main relay provided at the first end of the battery unit, a unit relay provided at the second end of the battery unit, and a precharge unit provided in parallel with the main relay. The precharge unit comprises a pre-resistor and a precharge relay connected in series with the pre-resistor. The control device includes a pre-charge processing execution unit that, when the plurality of battery modules are connected to the load through the pair of output terminals, controls the plurality of battery modules to be connected to the pair of output terminals after performing a pre-charge process on one of the plurality of battery modules at a time. The pre-charge process involves, for one battery module, turning off the main relay and turning on the unit relay and the pre-charge relay, and then, if the difference between the main voltage acting between the pair of output terminals and the unit voltage of the battery unit in the one battery module is less than or equal to a predetermined threshold, turning on the main relay of the one battery module and turning off the pre-charge relay. In addition, the control device for the battery system disclosed herein includes a cooling time T, which is the elapsed time since the previous pre-charge process for the battery module that was ranked first in the previous connection to the load and for which the pre-charge process was first executed during the previous connection. C A time acquisition unit for acquiring the cooling time T C The predetermined reference time T D The system further includes an order determination unit that determines the order of the pre-charge processing so that, in the following cases, the pre-charge processing is not performed first on the battery module that was ranked first in the previous order when connecting to the load.

[0006] In conventional battery systems, pre-charging is performed sequentially on multiple battery modules. At this time, a very large current flows through the pre-resistor of the battery module that is pre-charged first (hereinafter also referred to as the "first-ranked battery module"). Therefore, the pre-resistor of the first-ranked battery module tends to overheat during pre-charging. If pre-charging is performed again on the same battery module without sufficient cooling time, the pre-resistor becomes extremely hot. Repeating pre-charging without sufficient cooling time in this way causes preferential degradation of only the pre-resistor of the first-ranked battery module. In contrast, the battery system disclosed herein has a cooling time T, which is the elapsed time since the previous pre-charging of the first-ranked battery module. C Obtain this. And this cooling time T C is the reference time T D If the following conditions are met, it is determined that the pre-resistor of the battery module that was ranked first in the previous sequence has not been sufficiently cooled, and the order of pre-charging is determined so that another battery module becomes ranked first in the next sequence. This prevents repeated pre-charging of high-temperature pre-resistors, thereby suppressing uneven degradation of pre-resistors among multiple battery modules. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing a battery system according to an embodiment. [Figure 2] This figure illustrates the elapsed time and cooling time in the technology disclosed herein. [Figure 3] This flowchart shows the procedure for performing a pre-charge process on the first to third battery modules. [Figure 4] This is a flowchart showing the detailed procedure for step S103 in Figure 3. [Figure 5] This is a timing chart showing the procedure for performing a pre-charge process on the first to third battery modules. [Modes for carrying out the invention]

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

[0009] Figure 1 is a schematic diagram showing a battery system 1 according to this embodiment. As shown in Figure 1, the battery system 1 is connected to a load 100. The load 100 is not particularly limited, but could be, for example, a drive device such as an electric motor of a vehicle, or an inverter. A smoothing capacitor may be connected to the load 100 to reduce sudden changes in current. Here, the battery system 1 is installed in a vehicle such as a hybrid car or an electric vehicle and used as a power source to supply power to an electric motor that drives the vehicle. However, the battery system 1 is not limited to use in a vehicle.

[0010] The battery system 1 comprises 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. In this case, one of the output terminals 5 is the positive terminal, and the other output terminal 5 is the negative terminal.

[0011] Multiple battery modules 10 are connected to a pair of output terminals 5. In this embodiment, the multiple battery modules 10 are connected to a main bus 8, and the main bus 8 is connected to a pair of output terminals 5. Therefore, the multiple battery modules 10 are connected to the pair of output terminals 5 via the main bus 8. In addition, the multiple 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 kinetic energy or supply regenerative power to the battery modules 10. The multiple battery modules 10 are arranged in parallel (in other words, connected). The number of battery modules 10 is not particularly limited, but in this embodiment there are three. Here, the three battery modules 10 will be appropriately referred to as the first battery module 10A, the second battery module 10B, and the third battery module 10C. The battery module 10 includes the first battery module 10A, the second battery module 10B, and the third battery module 10C. In the following explanation, the term "battery module 10" will be used when referring to a description common to the first battery module 10A through the third battery module 10C.

[0012] In this embodiment, the configuration of the first battery module 10A to the third battery module 10C is the same. One battery module 10 includes a plurality of single cells 11, a main relay 20, a unit relay 30, a pre-charge unit 40, and a battery control device 50. The single cells 11 are rechargeable and dischargeable. As single cells 11, for example, a secondary battery that can be repeatedly charged and discharged by the movement of a charge carrier between a pair of electrodes (e.g., a positive electrode and a negative electrode) via an electrolyte may be used. As single cells 11, for example, a lithium-ion secondary battery or a nickel-metal hydride battery may be used. The plurality of single cells 11 are connected in series. Here, the plurality of single cells 11 are connected in series via a busbar (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 5. The number of single cells 11 in the first battery module 10A to the third battery module 10C is the same, but may be different. Here, multiple single cells 11 connected in series are referred to as a battery unit 12. The battery unit 12 has multiple single cells 11 connected in series.

[0013] The main relay 20 is connected in series to multiple individual cells 11 (in other words, the battery unit 12). Here, the main relay 20 is located at the first end of the battery unit 12. Here, "first end" refers to the positive terminal end of the battery unit 12 (in other words, the multiple individual cells 11). However, the first end may also refer to the negative terminal end of the battery unit 12. That is, the main relay 20 may be located at the negative terminal 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 ON and OFF.

[0014] In this embodiment, turning the relay ON means that it is connected (e.g., closed). Turning the relay OFF means that it is not connected (e.g., open).

[0015] The unit relay 30 is connected in series to multiple single cells 11 (in other words, the battery unit 12). Here, the unit relay 30 is located at the second end of the battery unit 12. The "second end" refers to the end of the battery unit 12 (in other words, the multiple single cells 11) opposite to the first end. Here, the "second end" refers to the negative terminal end of the battery unit 12. However, the second end may also refer to the positive terminal end of the battery unit 12. That is, the unit relay 30 may be located at the positive terminal end of the battery unit 12. The unit relay 30 is a relay that switches the connection between the second end of the battery unit 12 and the load 100 ON and OFF.

[0016] The precharge unit 40 is provided in parallel with the main relay 20. In other words, the precharge unit 40 is connected in parallel with the main relay 20. Here, the precharge unit 40 is provided at the first end (in this case, the positive terminal end) of the battery unit 12 (for example, multiple single cells 11 connected in series). The precharge unit 40 is a circuit that suppresses the inrush current 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 comprises a pre-resistor 41 and a precharge relay 42 connected in series with the pre-resistor 41. The precharge relay 42 can be switched ON and OFF.

[0017] The battery control device 50 is connected to a plurality of individual cells 11. The battery control device 50 is made up of a circuit board and has so-called registers. The battery control device 50 may be made up of, for example, a microcontroller. The battery control device 50 has an individual cell voltage detector 51, an equalizer 52, and a battery unit voltage detector 53.

[0018] The single-cell voltage detector 51 detects the voltage of each of the multiple single cells 11 that make up the battery unit 12. The single-cell voltage detector 51 is implemented, for example, by a circuit capable of detecting the voltage of each of the multiple single cells 11. The single-cell voltage detector 51 may have, for example, multiple connection terminals connected to the positive and negative terminals of each single cell 11 that make up the battery unit 12.

[0019] The equalizer 52 equalizes the remaining capacities of the multiple single cells 11 that make up the battery unit 12 based on the single cell voltage of each single cell 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 capacities of the multiple single cells 11. The equalizer 52 is implemented by a so-called equalization circuit. Although not shown in the figures, the equalizer 52 may be implemented by a control circuit and, for example, a plurality of discharge circuits connected between a plurality of connection terminals connected to the positive and negative electrodes of the single cell 11. Each of the plurality of discharge circuits comprises a discharge resistor and a switching element. The control circuit is configured 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, for example, via 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 discharge the cell 11 with a higher voltage to match the cell voltage of the cell 11 with a lower voltage as needed.

[0020] The battery unit voltage detector 53 detects the unit voltage of multiple single cells 11 (in other words, the battery unit 12) connected in series. The battery unit voltage detector 53 is implemented, 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 terminals of the multiple single cells 11 that make up the battery unit 12. The battery unit voltage detector 53 may also detect the unit voltage of the battery unit 12 by, for example, summing the single cell voltages of each single cell 11 detected by the single cell voltage detector 51.

[0021] The control device 60 is configured, for example, by a microcontroller. The control device 60 includes a communication interface, a central processing unit (CPU) that executes instructions for the control program, a read-only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as memory that stores the program and various data. The control device 60 is electrically connected to the main relays 20 and unit relays 30 of the multiple battery modules 10 (here, the first battery module 10A to the third battery module 10C), the precharge relay 42 of the precharge unit 40, and the battery control device 50. For each battery module 10, the control device 60 controls the ON and OFF switching of the main relay 20, unit relay 30, and precharge relay 42. In this embodiment, as shown in Figure 1, a power supply 70 is connected to the control device 60. Power is supplied to the control device 60 from the power supply 70.

[0022] In this embodiment, as shown in Figure 1, the control device 60 includes a main voltage acquisition unit 61, a unit voltage acquisition unit 63, a time acquisition unit 64, a sequence determination unit 65, a precharge processing execution unit 67, and a storage unit 69. The main voltage acquisition unit 61, the unit voltage acquisition unit 63, the sequence determination unit 65, the precharge processing execution unit 67, and the storage unit 69 may be implemented by one or more processors or by circuits.

[0023] The main voltage acquisition unit 61 acquires the total main voltage of multiple battery modules 10 connected in parallel. In other words, the main voltage acquisition unit 61 acquires the main voltage acting between a pair of output terminals 5. To put it another way, the main voltage acquisition unit 61 acquires the main voltage between the main buses 8. The configuration of the main voltage acquisition unit 61 is not particularly limited as long as it can acquire the main voltage. For example, the main voltage acquisition unit 61 may be implemented by a circuit capable of detecting the main voltage between a pair of output terminals 5. The main voltage acquisition unit 61 may be provided with connection terminals that are connected to, for example, the positive terminal side main bus 8 and the negative terminal side main bus 8 (or the pair of output terminals 5).

[0024] The unit voltage acquisition unit 63 acquires the unit voltage, which is the voltage of the battery unit 12, for each of the multiple battery modules 10. In this embodiment, the unit voltage acquisition unit 63 acquires the unit voltages of the first battery module 10A to the third battery module 10C. In this embodiment, the unit voltage acquisition unit 63 acquires the unit voltage from the battery unit voltage detector 53 of the battery control device 50 for 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 acquisition unit 63 acquires the unit voltage by receiving the unit voltage transmitted from the battery unit voltage detector 53.

[0025] The pre-charge processing execution unit 67 performs pre-charge processing on each of the multiple battery modules 10 when the multiple battery modules 10 are connected to the load 100 through a pair of output terminals 5. The pre-charge processing execution unit 67 performs pre-charge processing on one battery module 10 at a time from among the multiple battery modules 10. In this embodiment, the pre-charge processing execution unit 67 performs pre-charge processing independently on the first battery module 10A, the second battery module 10B, and the third battery module 10C. For example, the pre-charge processing execution unit 67 performs pre-charge processing on the first battery module 10A, and after the pre-charge processing on the first battery module 10A is completed, the pre-charge processing execution unit 67 performs pre-charge processing on the second battery module 10B. Then, after the pre-charge processing on the second battery module 10B is completed, the pre-charge processing execution unit 67 performs pre-charge processing on the third battery module 10C.

[0026] Here, pre-charge processing is a process to suppress inrush current flowing to the load 100 by controlling the flow of current 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 pre-charge processing, inrush current flowing to the load 100 can be suppressed by actively flowing current to the pre-charge unit 40 without flowing current to the main relay 20. In this embodiment, pre-charge processing is performed on the target battery module 10 by turning OFF the main relay 20 and turning ON the unit relay 30 and pre-charge relay 42, and 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 battery module 10 is set to a predetermined threshold V thIn the case described below (see FIG. 2), this is a process of turning on the main relay 20 of one battery module 10 and turning off the precharge relay 42. Here, the precharge process is performed such that after turning on the unit relay 30 while the main relay 20, the unit relay 30, and the precharge relay 42 are all off, the precharge relay 42 is turned on, and when the difference between the main voltage and the unit voltage reaches a threshold V th or less, the main relay 20 is turned on and the precharge relay 42 is turned off.

[0027] The time acquisition unit 64 acquires a cooling time T, which is the elapsed time ΔT from the previous precharge process of the battery module 10 ranked first in the previous order, for which the precharge process was first executed when connected to the load last time C . Hereinafter, the elapsed time ΔT and the cooling time T in the present specification C will be described. FIG. 2 is a diagram explaining the elapsed time and the cooling time in the technology disclosed herein. First, "elapsed time ΔT" as used herein refers to the time from when the precharge process was first most recently executed. Specifically, in the example shown in FIG. 2, the first battery module 10A is ranked first in the (n-1)th precharge process. In this case, the elapsed time ΔT of the first battery module 10A u1 is the time from the start of the (n-1)th precharge process to the start of the n-th precharge process. Further, the second battery module 10B is ranked first in the (n-3)th precharge process. In this case, the elapsed time ΔT of the second battery module 10B u2 is the time from the start of the (n-3)th precharge process to the start of the n-th precharge process. Then, the third battery module 10C is ranked first in the (n-2)th precharge process. In this case, the elapsed time ΔT of the third battery module 10C u3This represents the time from the start of the (n-2)th pre-charge process to the start of the (n)th pre-charge process. In the example shown in Figure 2, the first battery module 10A is the "battery module ranked first in the previous order" for which the previous (n-1) pre-charge process was performed. In this case, the time acquisition unit 64 receives the elapsed time ΔT of the first battery module 10A. u1 "Cooling time T" C It is considered as follows. The time acquisition unit 64 then determines the elapsed time ΔT of the first battery module 10A. u1 "Cooling time T" C This is transmitted to the sequence determination unit 65 as . In addition, in this embodiment, the elapsed time ΔT of the other battery module 10 u2 ΔT u3 This is also transmitted to the order determination unit 65.

[0028] The sequence determination unit 65 determines the order in which to perform the pre-charge process on the multiple battery modules 10. In this embodiment, the sequence determination unit 65 determines the order in which to perform the pre-charge process on the multiple battery modules 10. C The predetermined reference time T D If the following conditions are met, the order of pre-charging is determined so that the pre-charging process is not performed first on the battery module that was ranked first in the previous connection to the load 100. This prevents the pre-charging process from being repeated on a battery module whose pre-resistor 41 is not sufficiently cooled (in this case, the first battery module 10A), thereby suppressing uneven degradation of the pre-resistor 41 in multiple battery modules 10.

[0029] The following describes the detailed control by the sequence determination unit 65. Figure 3 is a flowchart showing the procedure for performing a pre-charge process on the first to third battery modules. Figure 4 is a flowchart showing the detailed procedure for step S103 in Figure 3. Figure 5 is a timing chart showing the procedure for performing a pre-charge process on the first to third battery modules. Here, before the flowchart in Figure 3 starts, the main relay 20, unit relay 30, and pre-charge relay 42 in the first to third battery modules 10A to 10C are in the OFF state, as shown at time t0 in Figure 5.

[0030] First, in step S101 in Figure 3, the unit voltage acquisition unit 63 in Figure 1 acquires the unit voltage V of the first battery module 10A. u1 , Unit voltage V of the second battery module 10B u2 , Unit voltage V of the third battery module 10C u3 Here, the unit voltage acquisition unit 63 obtains the unit voltage V from each battery unit voltage detector 53 of the first battery module 10A to the third battery module 10C. u1 , V u2 , V u3 The unit voltage V obtained by the unit voltage acquisition unit 63 is acquired. u1 , V u2 , V u3 This is stored in the memory unit 69 (see Figure 1).

[0031] Next, in step S102, the time acquisition unit 64 records the cooling time T of the battery module that was ranked first in the previous step. C Specifically, the time acquisition unit 64 in this embodiment acquires the elapsed time ΔT from the time the most recent pre-charge process was first performed for each of the multiple battery modules 10A to 10C. u1 ~ΔT u3 The time acquisition unit 64 then obtains the elapsed time ΔT. u1 ~ΔT u3 The battery module 10 with the shortest time is considered the battery module that ranked first last time, and the elapsed time of that battery module is used as the cooling time T.C This is considered to be the elapsed time ΔT. u1 ~ΔT u3 and cooling time T C The measurement procedure has already been explained, so we will omit any redundant explanations. In the following explanation, we will use the case where the first battery module 10A was the battery module ranked first in the previous test (see Figure 2) as an example.

[0032] Next, in step S103 of Figure 3, the sequence determination unit 65 of Figure 1 determines the order in which the pre-charge process will be performed on the first battery module 10A to the third battery module 10C. In the battery system 1 according to this embodiment, the order in which the pre-charge process will be performed is determined according to the procedure shown in Figure 4.

[0033] First, as shown in step S10 in Figure 4, the sequence determination unit 65 determines the unit voltage V acquired in step S101. u1 , V u2 , V u3 Based on this, multiple battery modules 10A to 10C are arranged in descending order. For example, in this embodiment, the unit voltage V u1 , V u2 , V u3 Assume the values ​​decrease in this order. In this case, the execution order of the next (nth) pre-charge process is set as follows: first battery module 10A, second battery module 10B, third battery module 10C.

[0034] Next, in step S20, the sequence determination unit 65 determines the cooling time T C (That is, the elapsed time ΔT of the first battery module 10A) u1 ) is the reference time T D Determine whether the following conditions are met. Here, the cooling time T C is the reference time T D If it exceeds (No. in step S20), it is understood that the pre-resistor 41 of the battery module that was ranked first in the previous sequence (first battery module 10A) is sufficiently cooled. For this reason, the sequence determination unit 65 determines the unit voltage V u1 , V u2 , V u3The process proceeds to step S30 without changing the execution order set based on the above. Then, in step S30, after determining the execution order of the precharge process, the process proceeds to S105 in Figure 3.

[0035] On the other hand, cooling time T C is the reference time T D If the following is the case (Yes in step S20), it is determined that the pre-resistor 41 of the battery module that was ranked first in the previous step is still hot. In this case, the order of the pre-charge processes is changed so that the pre-charge process is not performed first on the battery module that was ranked first in the previous step during the next (n-th) pre-charge process.

[0036] Specifically, the sequence determination unit 65 determines the elapsed time ΔT of all of the multiple battery modules 10A to 10C. u1 ~ΔT u3 is the reference time T D It is determined whether the following conditions are met (step S40). Then, the elapsed time ΔT of the multiple battery modules 10A to 10C is determined. u1 ~ΔT u3 Within the reference time T D If there is a value exceeding this (No. in step S40), it is understood that there is a battery module 10 whose pre-resistor 41 has been sufficiently cooled. In this case, the sequence determination unit 65 proceeds to step S50 in Figure 4, and changes the order of the pre-charge process for the battery module that was ranked first in the previous sequence (first battery module 10A) to second place or later when connecting to the load 100 next time. For example, in the example shown in Figure 2, the sequence determination unit 65 shifts the order of the first battery module 10A to second place in the next (nth) pre-charge process. Then, the elapsed time ΔT u2 is the reference time T D The second battery module 10B, which was exceeding the order, is moved up to first place in the sequence. After this change in order, the sequence determination unit 65 proceeds to step S30 to determine the execution order, and then proceeds to S105 in Figure 3. This prevents the first pre-charge process, which is likely to cause heat generation of the pre-resistor 41 due to inrush current, from being performed on the first battery module 10A, whose pre-resistor 41 is not sufficiently cooled.

[0037] Furthermore, in step S40, the elapsed time ΔT of all battery modules 10A to 10C is measured. u1 ~ΔT u3 is the reference time T D If the following is the case (Yes in step S40), it is understood that the pre-resistors 41 of all battery modules 10A to 10C are not sufficiently cooled. In this case, the control device 60 performs a predetermined error processing (S60). For example, the battery system 1 according to this embodiment performs a process to prohibit the main relay 20, the unit relay 30, and the pre-charge relay 42 from being turned ON as the error processing. This prevents the pre-charge process from starting when all pre-resistors 41 are at a high temperature, and thus more effectively suppresses thermal degradation of the pre-resistors 41.

[0038] As described above, after determining the execution order of the pre-charge process in step S103 in Figure 3, the control device 60 executes steps S105 to S117 in order according to that execution order. For example, in the example shown in Figure 2, the order determination unit 65 determines the execution order to be second battery module 10B, first battery module 10A, and third battery module 10C. In this case, the nth pre-charge process is performed according to the following procedure.

[0039] First, in the nth pre-charge process, steps S105 to S117 in Figure 3 are executed sequentially for the second battery module 10B, which is ranked first. First, in step S105, the pre-charge process execution unit 67 turns on the unit relay 30 of the second battery module 10B. Next, in step S107, the pre-charge relay 42 of the second battery module 10B is turned on. In Figure 5, for the second battery module 10B, the unit relay 30 is turned on at time t11, and the pre-charge relay 42 is turned on at time t12. Note that the order of processing in steps S105 and S107 may be reversed, and the unit relay 30 may be turned on after the pre-charge relay 42 is turned on. At time t12, since the unit relay 30 and the pre-charge relay 42 are turned on, current flows to the pre-charge unit 40, causing the main voltage V acting between the pair of output terminals 5 to increase. um The value gradually increases.

[0040] Subsequently, in step S109, the main voltage acquisition unit 61 acquires the main voltage V um In step S111, the unit voltage acquisition unit 63 acquires the unit voltage V of the second battery module 10B. u2 The main voltage V is obtained. Then, in step S113 of Figure 3, the pre-charge processing execution unit 67 of Figure 1 obtains the main voltage V. um And, the unit voltage V uS (Here, V u2 The difference between (|V) um -V u2 |) is threshold V th Determine whether the following is true. Here, the main voltage V um and unit voltage V u2 The difference between this and the threshold V th If it is greater, return to step S109. Meanwhile, the main voltage V um and unit voltage V u2 The difference between this and the threshold V th In the following cases, proceed to step S115.

[0041] In step S115, the pre-charge processing unit 67 turns on the main relay 20 for the second battery module 10B. Also, in step S117, the pre-charge processing unit 67 turns off the pre-charge relay 42. In Figure 5, the main relay 20 is turned on for the second battery module 10B at time t13, and the pre-charge relay 42 is turned off at time t14. Here, the pre-charge processing for the second battery module 10B is performed between time t11 and time t14.

[0042] After the pre-charge process is performed on the first-ranked second battery module 10B, the pre-charge process is then performed on the second-ranked first battery module 10A by sequentially executing steps S105 to S117 in Figure 3. Here, the pre-charge process execution unit 67 performs the pre-charge process on the first battery module 10A after the pre-charge process for the second battery module 10B is completed (after time t14 in Figure 5). At this time, the pre-charge relay 42 of the first-ranked second battery module 10B is OFF, and the main relay 20 and unit relay 30 are ON. In this state, the pre-charge process for the first battery module 10A is executed. Note that the processes in steps S105 to S117 for the first battery module 10A are substantially the same as those for the second battery module 10B, so their explanation is omitted. In Figure 5, for the first battery module 10A, the unit relay 30 turns ON at time t21, which is later than time t14, and the precharge relay 42 turns ON at time t22. Subsequently, from time t22 to time t23, the precharge process for the first battery module 10A is performed. Then, the main voltage V um and unit voltage V u1 The difference between this and the threshold V th At time t23, the main relay 20 turns ON, and at time t24, the precharge relay 42 turns OFF. Here, the precharge process for the first battery module 10A is performed between time t21 and time t24.

[0043] After pre-charging is performed on the first-ranked second battery module 10B and the second-ranked first battery module 10A, pre-charging is performed on the third-ranked third battery module 10C by sequentially executing steps S105 to S117. Here, pre-charging is performed on the third battery module 10C with both the first battery module 10A and the second battery module 10B's pre-charge relays 42 OFF, and the main relay 20 and unit relay 30 ON. Note that the processes in steps S105 to S117 for the third battery module 10C are substantially the same as those for the second battery module 10B and the first battery module 10A, so their explanation is omitted here. In Figure 5, for the third battery module 10C, the unit relay 30 turns ON at time t31, which is after time t24, and the pre-charge relay 42 turns ON at time t32. Subsequently, a pre-charge process is performed on the third battery module 10C between time t32 and time t33. Then, the main voltage V um and unit voltage V u3 The difference between this and the threshold V th At time t33, the main relay 20 turns ON, and at time t34, the precharge relay 42 turns OFF. Here, the precharge process for the third battery module 10C is performed between time t31 and time t34. As described above, the precharge process execution unit 67 independently executes the precharge process for each battery module 10A to 10C according to the execution order determined by the sequence determination unit 65. After these precharge processes are performed, each battery module 10A to 10C is connected to the load 100. This prevents inrush current from flowing into the load 100.

[0044] As described above, in the present embodiment, as shown in FIG. 1, the battery system 1 includes a pair of output terminals 5 connected to a 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 plurality of battery modules 10 comprises: a battery unit 12 having a plurality of single cells 11 connected in series; a main relay 20 provided at an end on a first side of the battery unit 12 (here, an end on a positive electrode side); a unit relay 30 provided at an end on a second side of the battery unit 12 (here, an end on a negative electrode side); and a precharge unit 40 provided in parallel with the main relay 20. The precharge unit 40 includes a precharging resistor 41 and a precharging relay 42 connected in series to the precharging resistor 41. When the plurality of battery modules 10 are connected to the load 100 via the pair of output terminals 5, the control device 60 executes precharge processing for each one of the plurality of battery modules 10, and then includes a precharge processing execution unit 67 that controls the plurality of battery modules 10 to be connected to the pair of output terminals 5. The precharge processing is performed as follows: for one target battery module 10, after the main relay 20 is turned off, and the unit relay 30 and the precharge relay 42 are turned on, the difference between the main voltage applied between the pair of output terminals 5 and the unit voltage of the battery unit 12 in the one battery module 10 is equal to a predetermined threshold value V th (see FIG. 2) When the difference is equal to or less than the threshold value, the precharge processing is processing for turning on the main relay 20 of the one battery module 10 and turning off the precharge relay 42. In addition, the control device 60 of the battery system 1 calculates the elapsed time ΔT from the previous precharge processing of the battery module that was ranked first in the previous order (the first battery module 10A in FIG. 2) on which the precharge processing was first performed in the previous connection to the load 100 th 9>which is the cooling time T C a time acquisition unit 64 that acquires the cooling time T, and the cooling time T C is a predetermined reference time T Dwhen it is equal to or less than the reference time, further comprising an order determining unit (65) that determines the order of precharge processing such that the precharge processing is not first performed on the battery module that was first in the order in the previous time (the first battery module (10A)) when connecting to the load (100) next time.

[0045] In a general battery system, a very large current flows through the pre-charge resistor of the battery module that is first in the order, so the pre-charge resistor is prone to heat generation. If precharge processing is performed again without leaving sufficient cooling time, the pre-charge resistor will reach a very high temperature, which accelerates the deterioration of the pre-charge resistor. In contrast, the battery system 1 according to the present embodiment calculates the elapsed time ΔT from the precharge processing of the battery module that was first in the previous order (the first battery module 10A in FIG. 2) u1 as the cooling time T C for acquisition. Then, this cooling time T C is equal to or less than the reference time T D when the above condition is satisfied, it is determined that the pre-charge resistor 41 of the battery module 10A that was first in the previous order is at a high temperature, and the order of precharge processing is determined such that the other battery modules 10B and 10C become first in the order next time. This can prevent precharge processing from being repeatedly performed on a high-temperature pre-charge resistor 41, thereby suppressing uneven deterioration of the pre-charge resistors 41 among the plurality of battery modules 10A to 10C.

[0046] Note that in the battery system 1 according to the present embodiment, the temperature of the pre-charge resistor 41 is not measured, and the elapsed time ΔT U1 to ΔT U3 the order of precharge processing is determined based on the above. This provides the following advantages. First, in order to measure the temperature of the pre-charge resistor 41, it is necessary to attach a temperature sensor to the battery module 10. In this case, a large number of temperature sensors equal in number to the battery modules 10 are required, which causes an increase in component cost. In contrast, the elapsed time ΔT U1 to ΔT U3This can be measured simply by setting the timer in the control device 60. Furthermore, temperature measurement using a temperature sensor is difficult because a delay occurs due to heat conduction from the pre-resistor 41 to the temperature sensor, making it difficult to accurately reflect the internal temperature of the pre-resistor 41. In contrast, the amount of heat generated by the pre-resistor 41 due to the pre-charge process can be calculated, allowing for the time (reference time T) required for the pre-resistor to cool sufficiently. D ) can also be easily calculated. Therefore, the elapsed time ΔT U1 ~ΔT U3 Control based on this method allows for more precise timing than control based on temperature sensor detection results.

[0047] Furthermore, the control device 60 in this embodiment sets the unit voltage V, which is the voltage of the battery unit 12, for each of the multiple battery modules 10A to 10C. u1 ~V u3 The unit voltage acquisition unit 63 is included to acquire the unit voltages V acquired by the unit voltage acquisition unit 63. The sequence determination unit 65 then selects the multiple unit voltages V acquired by the unit voltage acquisition unit 63. u1 ~V u3 Based on this, multiple battery modules 10A to 10C are arranged in descending order. The order determination unit 65 then determines that the first battery module in the arranged order is the battery module that was ranked first in the previous order, and that the cooling time T C is the reference time T D If the following conditions are met, a different battery module from the one previously ranked first will be promoted to the battery module 10 that will be the first to undergo pre-charge processing when connected to the next load 100. First, by sequentially performing pre-charge processing on multiple battery modules 10 in an order that results in descending unit voltages, the potential difference between the main voltage and the unit voltage among the multiple battery modules 10 can be reduced. Therefore, overcurrents that may occur due to pre-charge processing can be suppressed. Furthermore, if the battery module that was previously ranked first is not sufficiently cooled, the order of pre-charge processing is changed. This allows for more effective suppression of the degradation of the pre-resistor 41.

[0048] Furthermore, the time acquisition unit 64 in this embodiment acquires the elapsed time ΔT from the time the most recent pre-charge process was first performed for each of the multiple battery modules 10A to 10C. u1 ~ΔT u3 The control device 60 then obtains the elapsed time ΔT of all the battery modules 10A to 10C. u1 ~ΔT u3 is the reference time T D If the following conditions are met, a predetermined error handling procedure is performed. This effectively suppresses the degradation of battery modules other than the battery module that was ranked first in the previous sequence. In this embodiment, the error handling procedure prohibits the main relay 20, the unit relay 30, and the precharge relay 42 from being turned ON. This prevents the precharge process from being performed when all pre-resistors 41 are at a high temperature. As a result, thermal degradation of the pre-resistors 41 can be suppressed more reliably.

[0049] An embodiment of the battery system disclosed herein has been described above. However, the above-described embodiment is not intended to limit the technology disclosed herein, and various modifications can be made.

[0050] For example, the error handling in the above embodiment prohibits the main relay 20, unit relay 30, and precharge relay 42 from being turned ON. However, the specific content of the error handling is not limited to the above embodiment and can be appropriately changed depending on the configuration and purpose of the battery system 1. For example, the error handling may be performed when the elapsed time ΔT of the multiple battery modules 10A to 10C has elapsed. u1 ~ΔT u3 The longest elapsed time for a battery module is shown (in Figure 2, the elapsed time ΔT for the second battery module 10B). u2 ) is the reference time T D Alternatively, the process may involve prohibiting the start of the pre-charge process until a certain threshold is exceeded. In this case, there will be a slight delay in the start of the pre-charge process, but the thermal degradation of the pre-resistors 41 of battery modules other than the battery module that was ranked first in the previous ranking can be more effectively suppressed.

[0051] Furthermore, error handling is performed using the elapsed time ΔT among multiple battery modules 10A to 10C. u1 ~ΔT u3 The order of pre-charging processes may be determined so that the pre-charging process is performed first on the battery module with the longest time (the second battery module 10B in Figure 2). In other words, in this error handling, the elapsed time ΔT u1 ~ΔT u3 All of these are reference time T D If the threshold is not exceeded, the pre-charge process starts with the battery module 10 that has cooled the most. When such error processing is set, the degradation of the pre-resistor 41 can be minimized as much as possible in order to start the pre-charge process without delay. The control device 60 may store all of the above-mentioned error processing methods. In this case, it is preferable that the control device 60 is configured so that the user can select the appropriate error processing method from among the multiple error processing methods.

[0052] Furthermore, in the above-described embodiment, first, the unit voltage V u1 ~V u3 The order of pre-charging is set based on this. Then, the elapsed time ΔT of the battery module 10A, which was ranked first in the previous sequence. u1 (Cooling time T C Based on this, the pre-resistor 41 rearranges the order of pre-charging processes so that the pre-charging process for the high-temperature battery module 10 is not performed first. However, the order of pre-charging processes is determined by the unit voltage V of the battery modules 10A~10C. u1 ~V u3 Without considering the elapsed time ΔT u1 ~ΔT u3 It may be determined solely based on the elapsed time ΔT of the multiple battery modules 10A to 10C. u1 ~ΔT u3 Based on this, the order of the second and subsequent components in the pre-charge process can also be determined. For example, as shown in Figure 2, the order of the second battery module 10B, the third battery module 10C, and the first battery module 10A is determined by the elapsed time ΔT. u1 ~ΔT u3If the time is long, the pre-charging process may be performed in this order. This allows each of the multiple battery modules 10A to 10C to be cooled more efficiently.

[0053] Furthermore, in the above embodiment, the elapsed time ΔT of each of the multiple battery modules 10A to 10C u1 ~ΔT u3 The following is obtained. The battery module 10 with the shortest elapsed time among these (the first battery module 10 in Figure 2) is designated as the "battery module that was ranked first in the previous ranking," and the elapsed time of the battery module that was ranked first in the previous ranking (elapsed time ΔT of the first battery module 10) is determined. u1 ) to "cooling time T C " is considered to be "cooling time T C " represents the total elapsed time ΔT of multiple battery modules 10A~10C u1 ~ΔT u3 It is possible to measure without obtaining the data. For example, if the memory unit 69 of the control device 60 stores the history of the battery module that was ranked first in the previous ranking, the battery module that was ranked first in the previous ranking can be determined without measuring the elapsed time of all battery modules. Then, by measuring the elapsed time of the battery module that was ranked first in the previous ranking, determined based on this history, the cooling time T can be determined. C It allows for selective measurement of only certain parameters.

[0054] Furthermore, in the above-described embodiment, as shown in step S10 in Figure 4, the unit voltage V acquired in step S101 is u1 , V u2 , V u3 Based on this, multiple battery modules 10A to 10C are arranged in descending order. However, the order in which the multiple battery modules are arranged based on their unit voltage is not limited to descending order; it may also be in ascending order. Even when the pre-charge process is performed sequentially with the units arranged in ascending order of their unit voltage, the potential difference between the main voltage and the unit voltage between the multiple battery modules 10 can be reduced. As a result, overcurrents that may occur due to the pre-charge process can be suppressed.

[0055] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments and other details 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 and each process mentioned herein can be omitted or combined as appropriate, unless no particular problems arise.

[0056] As described above, this specification includes the disclosures set forth in the following sections. Section 1: A pair of output terminals connected to the load, Multiple battery modules connected to the aforementioned pair of output terminals and arranged in parallel, Control device and Equipped with, The aforementioned plurality of battery modules A battery unit having multiple single cells connected in series, A main relay is provided at the first end of the aforementioned battery unit, A unit relay is provided at the second end of the aforementioned battery unit, A pre-charge unit is provided in parallel with the main relay, Each is equipped with, The aforementioned pre-charge unit is Pre-resistor and, A pre-charge relay connected in series with the aforementioned pre-resistor, Equipped with, The control device includes a pre-charge processing execution unit that, when the plurality of battery modules are connected to the load through the pair of output terminals, performs a pre-charge process on each of the plurality of battery modules before controlling the plurality of battery modules to be connected to the pair of output terminals. The pre-charge process involves, for one battery module, turning off the main relay and turning on the unit relay and the pre-charge relay, and then, if the difference between the main voltage acting between the pair of output terminals and the unit voltage of the battery unit in the one battery module is less than or equal to a predetermined threshold, turning on the main relay of the one battery module and turning off the pre-charge relay. The control device is Cooling time T is the elapsed time since the previous pre-charge process for the battery module that was ranked first in the previous sequence when the pre-charge process was first performed upon connection to the load. C A time acquisition unit that acquires the time, The cooling time T C The predetermined reference time T D If the following conditions are met, an order determination unit determines the order of the pre-charge processing so that the pre-charge processing is not performed first on the battery module that was ranked first in the previous order when connecting to the load, A battery system that also includes additional features.

[0057] Section 2: The control device includes a unit voltage acquisition unit that acquires a unit voltage, which is the voltage of the battery unit, for each of the plurality of battery modules. The order determination unit arranges the plurality of battery modules in ascending or descending order based on the plurality of unit voltages obtained by the unit voltage acquisition unit, and the first battery module in the arranged order is the battery module that was ranked first in the previous order, and the cooling time T C The aforementioned reference time T D The battery system according to item 1, wherein, if the following conditions are met, another battery module different from the previously ranked first battery module is promoted to the battery module in which the pre-charge process is performed first when the next connection to the load is made.

[0058] Section 3: The battery system according to item 1 or 2, wherein the time acquisition unit acquires the elapsed time for each of the plurality of battery modules from the time the pre-charge process was first performed most recently.

[0059] Section 4: The control device determines that the elapsed time of all of the plurality of battery modules is the reference time T. D The battery system described in item 3 performs predetermined error handling if any of the following conditions are met:

[0060] Section 5: The battery system according to item 4, wherein the error handling is a process that prohibits turning on the main relay, the unit relay, and the precharge relay, respectively.

[0061] Item 6: The battery system according to item 4, wherein the error handling is a process of prohibiting the start of the pre-charge process until the elapsed time of the battery module with the longest elapsed time among the plurality of battery modules exceeds the reference time.

[0062] Section 7: The battery system according to paragraph 4, wherein the error handling is a process that determines the order of the pre-charge processes so that the battery module with the longest elapsed time among the plurality of battery modules is the first to be connected to the load the next time the pre-charge process is performed.

[0063] Section 8: The battery system according to any one of claims 1 to 7, wherein the sequence determination unit determines the order of the second and subsequent batteries in the pre-charge process based on the elapsed time of the plurality of battery modules. [Explanation of Symbols]

[0064] 1. Battery System 5 pairs of output terminals 10 Battery Modules 10A First Battery Module 10B Second Battery Module 10C Third Battery Module 11 single batteries 12 Battery Units 20 Main Relay 30 Unit Relays 40 Precharge Unit 41 Pre-resistor 42 Pre-charge relay 60 Control device 61 Main voltage acquisition unit 63 Unit voltage acquisition section 64-hour acquisition unit 65. Order Determination Section 67 Precharge Processing Execution Unit

Claims

1. A pair of output terminals connected to the load, Multiple battery modules connected to the aforementioned pair of output terminals and arranged in parallel, Control device and Equipped with, The aforementioned plurality of battery modules A battery unit having multiple single cells connected in series, A main relay is provided at the first end of the aforementioned battery unit, A unit relay is provided at the second end of the aforementioned battery unit, A pre-charge unit is provided in parallel with the main relay, Each is equipped with, The aforementioned pre-charge unit is Pre-resistor and, A pre-charge relay connected in series with the aforementioned pre-resistor, Equipped with, The control device includes a pre-charge processing execution unit that, when the plurality of battery modules are connected to the load through the pair of output terminals, performs a pre-charge process on each of the plurality of battery modules before controlling the plurality of battery modules to be connected to the pair of output terminals. The pre-charge process involves, for one battery module, turning off the main relay and turning on the unit relay and the pre-charge relay, and then, if the difference between the main voltage acting between the pair of output terminals and the unit voltage of the battery unit in the one battery module is less than or equal to a predetermined threshold, turning on the main relay of the one battery module and turning off the pre-charge relay. The control device is The cooling time T is the elapsed time since the previous pre-charge process for the battery module that was ranked first in the previous sequence when the pre-charge process was first performed upon connection to the load. Ｃ A time acquisition unit that acquires the time, The cooling time T Ｃ The predetermined standard time T Ｄ If the following conditions are met, an order determination unit determines the order of the pre-charge processing so that the pre-charge processing is not performed first on the battery module that was ranked first in the previous order when connecting to the load, A battery system that also includes additional features.

2. The control device includes a unit voltage acquisition unit that acquires a unit voltage, which is the voltage of the battery unit, for each of the plurality of battery modules. The order determination unit arranges the plurality of battery modules in ascending or descending order based on the plurality of unit voltages obtained by the unit voltage acquisition unit, and the first battery module in the arranged order is the battery module that was ranked first in the previous order, and the cooling time T Ｃ that is the aforementioned reference time T Ｄ The battery system according to claim 1, wherein, in the following cases, another battery module different from the previously ranked first battery module is promoted to the battery module in which the pre-charge process is performed first when the next connection to the load is made.

3. The battery system according to claim 1, wherein the time acquisition unit acquires the elapsed time for each of the plurality of battery modules from the time the pre-charge process was first performed most recently.

4. The control device determines that the elapsed time of all of the plurality of battery modules is the reference time T. Ｄ The battery system according to claim 3, wherein a predetermined error handling procedure is performed in the following cases.

5. The battery system according to claim 4, wherein the error handling is a process that prohibits turning on the main relay, the unit relay, and the precharge relay, respectively.

6. The battery system according to claim 4, wherein the error handling is a process of prohibiting the start of the pre-charge process until the elapsed time of the battery module with the longest elapsed time among the plurality of battery modules exceeds the reference time.

7. The battery system according to claim 4, wherein the error handling is a process that determines the order of the pre-charge processes so that the battery module with the longest elapsed time among the plurality of battery modules is the first to be connected to the load the next time the pre-charge process is performed.

8. The battery system according to claim 1, wherein the sequence determination unit determines the order of the second and subsequent pre-charge processes based on the elapsed time of the plurality of battery modules.

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