Charge capacity adjustment controller

Abstract

To continue cell balancing control while considering ON fixation of a semiconductor switching element for performing the cell balancing control when detecting the ON fixation.SOLUTION: A charge capacity adjustment controller 104 for controlling a cell controller 103 comprising a semiconductor switching element 102 for short-cutting a battery cell 100 via a resistor 101 comprises: an ON fixation detection unit 105 for detecting ON fixation of the semiconductor switching element; and a cell balancing controlling unit 106 for calculating and creating an instruction for ON / OFF of the semiconductor switching element for executing cell balancing control for reducing variation of charge capacities of a plurality of battery cells. When the ON fixation of the semiconductor switching element is detected, the cell balancing controlling unit creates the instruction in executing the cell balancing control so as to execute the cell balancing control by controlling a semiconductor switching element other than the semiconductor switching element where the ON fixation is detected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charge capacity adjustment control device. [Background technology]

[0002] Conventionally, cell balancing control is known in which a secondary battery composed of multiple battery cells is monitored, the charge capacity of each battery cell is calculated, and if there is a variation in the charge capacity of each battery cell, the semiconductor switching elements connected to each battery cell are controlled to suppress the variation in the charge capacity of each battery cell.

[0003] Cell balancing control is a control that reduces variations in the charge capacity of each battery cell by turning on semiconductor switching elements and discharging specific battery cells.

[0004] For example, Patent Document 1 discloses a method of cell balancing control in which a battery cell with the maximum charge capacity is targeted for cell balancing, and the targeted cell is individually discharged. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-299122 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional cell balancing control does not take into consideration the control that would occur if a semiconductor switching element connected to a specific battery cell fails and becomes stuck in the ON state.

[0007] If control for when the semiconductor switching element becomes stuck ON is not taken into consideration, there is a problem that, depending on the cell balancing control algorithm, the intended cell balancing control may not be able to be performed if the semiconductor switching element becomes stuck ON.

[0008] Therefore, when a semiconductor switching element is detected as stuck-ON, it is possible to stop the cell balancing control (not to perform the cell balancing control) including the battery cells connected to the semiconductor switching element that is not stuck-ON. However, in this case, only the battery cells connected to the semiconductor switching element that is stuck-ON continue to discharge, which causes a problem that the variation in charge capacity between the battery cells connected to the semiconductor switching element that is stuck-ON and the other battery cells becomes large. As a result of the large variation in charge capacity, the output of the secondary battery is limited or stopped, which causes a problem that the running of the vehicle equipped with the secondary battery is restricted.

[0009] The problem that the present invention aims to solve is to provide a charge capacity adjustment control device that, when it detects that a semiconductor switching element used for performing cell balancing control is stuck in the ON state, can continue cell balancing control while taking the stuck-on state into consideration. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the charge capacity adjustment control device of the present invention is a charge capacity adjustment control device that controls a cell controller provided with a semiconductor switching element that shorts out a corresponding battery cell among a plurality of battery cells that constitute a secondary battery via a resistor when turned ON, and has an ON fixation detection unit that detects whether the semiconductor switching element is stuck ON, and a cell balancing control unit that calculates and creates an ON / OFF command for the semiconductor switching element to execute cell balancing control that reduces variation in charge capacity of the plurality of battery cells, and is characterized in that when a semiconductor switching element is detected to be stuck ON, the cell balancing control unit creates the command to control the semiconductor switching elements other than the semiconductor switching element that is stuck ON when executing the cell balancing control. Effect of the Invention

[0011] According to the charge capacity adjustment control device of the present invention, when a stuck-ON state of a semiconductor switching element for performing cell balancing control is detected, the cell balancing control can be continued while taking the stuck-ON state into consideration. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a functional block diagram illustrating an overall configuration of an embodiment. [Diagram 2] 4 is a diagram illustrating a discharge path when a semiconductor switching element connected to a battery cell is turned ON. FIG. [Diagram 3] 1 is a flowchart illustrating an overall flow of cell balancing control in an embodiment. [Figure 4] 4 is a flowchart illustrating the operation of a cell balancing control unit in the charge capacity adjustment control device of the embodiment. [Diagram 5] 5 is a flowchart illustrating details of step S404 in FIG. 4. [Figure 6]10 is a diagram illustrating a discharge path when a semiconductor switching element adjacent to a semiconductor switching element that is stuck ON is turned ON. FIG. [Figure 7] FIG. 13 is a diagram showing the charge capacity of each battery cell when a semiconductor switching element is stuck ON and cell balancing control is stopped in a comparative example in which cell balancing control is stopped when a semiconductor switching element is stuck ON. [Figure 8] 11 is a diagram showing the charge capacity of each battery cell in a case where cell balancing control is continued even if a semiconductor switching element is stuck ON in the charge capacity adjustment control device of the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing and each embodiment, the same or similar components are designated by the same reference numerals, and duplicated explanations will be omitted.

[0014] In the embodiment, an example will be described assuming that cell balancing control is performed on a secondary battery mounted on an electric vehicle, but the present invention is not limited to this.

[0015] FIG. 1 is a functional block diagram illustrating the overall configuration of the embodiment.

[0016] The secondary battery is composed of a number of battery cells 100 (S1 to Sn) connected in series to each other. Resistors 101 (R1 to Rn+1) and capacitors C1 to Cn corresponding to the battery cells 100 (S1 to Sn) are connected to the battery cells 100 (S1 to Sn), respectively.

[0017] The cell controller 103 has a plurality of semiconductor switching elements 102 (BSW1 to BSWn) connected in series with each other.

[0018] The semiconductor switching element BSW1 and capacitor C1 corresponding to the battery cell S1 are connected in parallel via resistors R1 and R2. Similarly, the semiconductor switching elements BSW2 to BSWn and capacitors C2 to Cn corresponding to the battery cells S2 to Sn are connected in parallel via resistors R2 to Rn and R3 to Rn+1.

[0019] The cell controller 103 is connected to the charge capacity adjustment control device 104 so as to be able to communicate with it, and is controlled by commands from the charge capacity adjustment control device 104. Specifically, the cell controller 103 has a communication unit (not shown) and a drive unit (not shown), and receives ON / OFF commands for the semiconductor switching element 102 from the charge capacity adjustment control device 104 via the communication unit (not shown), and applies a control signal corresponding to this ON / OFF command to the semiconductor switching element 102 via the drive unit (not shown), thereby controlling the ON / OFF of the semiconductor switching element 102.

[0020] By turning on the semiconductor switching element 102, the corresponding battery cell 100 can be short-circuited and discharged via the resistor 101. The resistor 101 serves as a discharge resistor.

[0021] FIG. 2 is a diagram illustrating a discharge path when a semiconductor switching element connected to a battery cell is turned on.

[0022] 2, when the semiconductor switching element BSW1 connected to the battery cell S1 is turned ON, the battery cell S1 is discharged via resistors R1 and R2. The same applies to the discharge of the other battery cells 100; for example, when the semiconductor switching element BSWn connected to the battery cell Sn is turned ON, the battery cell Sn is discharged via resistors Rn and Rn+1.

[0023] The charge capacity adjustment control device 104 of this embodiment includes a stuck-ON detection unit 105 and a cell balancing control unit 106. The charge capacity adjustment control device 104 also includes a communication unit (not shown) and the like.

[0024] The charging capacity adjustment control device 104 can be constructed by executing a program on a computer system having, for example, an arithmetic processing device such as a CPU or MPU, a memory, an auxiliary storage device, an input unit, and an output unit, to realize various functional units such as an ON sticking detection unit 105, a cell balancing control unit 106, and a communication unit (not shown).

[0025] The stuck-ON detector 105 detects whether the semiconductor switching element 102 is stuck-ON.

[0026] The cell balancing control unit 106 calculates and creates ON / OFF commands for the semiconductor switching elements 102 to execute cell balancing control that reduces variation in charge capacity among the multiple battery cells 100. If a semiconductor switching element 102 is detected as stuck ON, a command is created to execute cell balancing control by controlling the semiconductor switching elements 102 other than the semiconductor switching element 102 that is stuck ON.

[0027] Even when the charge capacity adjustment control device 104 for performing cell balancing control detects that the semiconductor switching element 102 used for performing cell balancing control is stuck ON, it does not stop the cell balancing control but continues the cell balancing control taking the stuck ON into consideration, so that it is possible to reduce variation in charge capacity compared to a case in which the cell balancing control is stopped when the stuck ON state of the semiconductor switching element 102 is detected. If variation in charge capacity becomes large, there is a problem that the output of the secondary battery is limited or output is stopped, restricting the travel of the vehicle equipped with the secondary battery, but according to this embodiment, the time until the output of the secondary battery is limited or output is stopped is extended, and the travel distance of the vehicle can be increased.

[0028] FIG. 3 is a flowchart illustrating the overall flow of cell balancing control in the embodiment.

[0029] In step S301, the stuck-ON detection unit 105 and the cell controller 103 diagnose and detect the stuck-ON state of the semiconductor switching element 102. Specifically, the stuck-ON detection unit 105 transmits a command for diagnosis to the cell controller 103. The cell controller 103 turns off the semiconductor switching element 102, measures the voltage applied to the semiconductor switching element 102, and transmits the measurement result. The stuck-ON detection unit 105 detects the stuck-ON state of the semiconductor switching element 102 based on the received measurement result. For example, when the semiconductor switching element BSW1 is turned off, if the voltage across both ends of the semiconductor switching element BSW1 is 0 V, the same as when the semiconductor switching element BSW1 is turned on, it can be determined that the semiconductor switching element BSW1 is stuck-ON and short-circuited.

[0030] In step S302, the cell balancing control unit 106 determines whether or not cell balancing control is required, and calculates and creates an ON / OFF command for the semiconductor switching element 102. If cell balancing control is required, the ON / OFF command for performing cell balancing control is created taking into consideration the stuck-ON detection result. If cell balancing control is not required, a command to turn the semiconductor switching element 102 OFF is created.

[0031] In step S303, the charge capacity adjustment control device 104 transmits the command created in step S302 to the cell controller 103 via a communication unit (not shown).

[0032] In step S304, the cell controller 103 drives the semiconductor switching element 102 by a drive unit (not shown) in accordance with a command received via a communication unit (not shown).

[0033] 4 is a flowchart illustrating the operation of the cell balancing control unit in the charge capacity adjustment control device of the embodiment, showing details of the operation of step S302 in FIG.

[0034] In step S401, the cell balancing control unit 106 calculates the charge capacity of each battery cell 100. Specifically, the cell balancing control unit 106 calculates the charge capacity of each battery cell 100 based on the voltage of each battery cell 100 measured by the cell controller 103. Note that, although only one operation like this step S401 is shown in FIG. 4, it is executed appropriately as necessary, for example, before step S406.

[0035] In step S402, the cell balancing control unit 106 determines whether the variation in charge capacity is equal to or greater than the cell balancing start threshold. Specifically, the charge capacity of each battery cell 100 calculated in step S401 is analyzed to check whether there is variation in the charge capacity. The variation in charge capacity is found, for example, by calculating the difference between the maximum and minimum values ​​of the charge capacity of each battery cell 100. If the variation in charge capacity is smaller than the cell balancing start threshold, the process proceeds to step S403 and the cell balancing control is not executed. If the variation in charge capacity is equal to or greater than the cell balancing start threshold, the process proceeds to step S404 to execute the cell balancing control.

[0036] In step S403, since the cell balancing control is not executed, the cell balancing control unit 106 generates a command to turn off all the semiconductor switching elements 102. Then, the flow ends.

[0037] In step S404, in order to execute the cell balancing control, the cell balancing control unit 106 sets the discharge amount of each battery cell 100. Specifically, the cell balancing control unit 106 sets the discharge amount of each battery cell 100 when performing the cell balancing control based on the charge capacity of each battery cell 100 so as to reduce the variation in charge capacity. At this time, the target battery cell 100 and its discharge amount are set taking into consideration the detection result of the stuck-ON state. Details will be described later with reference to FIG. 5.

[0038] In step S405, in order to execute cell balancing control, the cell balancing control unit 106 generates a command to turn on the semiconductor switching element 102 of the battery cell 100 to be discharged, based on the discharge amount of each battery cell 100 set in step S405.

[0039] In step S406, the cell balancing control unit 106 determines whether the variation in charge capacity is smaller than the cell balancing stop threshold. If the variation in charge capacity is smaller than the cell balancing stop threshold, the process proceeds to step S407 and stops the cell balancing control. If the variation in charge capacity is equal to or greater than the cell balancing stop threshold, the process returns to step S404 to continue the cell balancing control.

[0040] In step S407, in order to stop the cell balancing control, the cell balancing control unit 106 generates a command to turn off all of the semiconductor switching elements 102. Then, the flow ends.

[0041] Through the above flow, when the variation in charge capacity of the multiple battery cells 100 becomes equal to or greater than the cell balancing start threshold, the cell balancing control unit 106 generates a command to start cell balancing control in step S405. Also, when the variation in charge capacity of the multiple battery cells 100 becomes smaller than the cell balancing stop threshold, the cell balancing control unit 106 generates a command to stop cell balancing control in step S407.

[0042] The commands created in steps S403, S405, and S407 are stored in a storage unit (not shown) by the cell balancing control unit 106. Then, in step S303 shown in FIG. 3, a communication unit (not shown) of the charging capacity adjustment control device 104 transmits the commands stored in the storage unit (not shown) to the cell controller 103.

[0043] A series of processes including command creation in step S302 (command creation in any of step S403, step S405, or step S407), transmission in step S303, and driving in step S304 are executed, for example, at a predetermined cycle of 100 ms. Note that this is not limited to this, and some of the cycles may be different, for example, by executing command creation in step S302 at a predetermined cycle of 1000 ms, and executing transmission in step S303 and driving in step S304 at a predetermined cycle of 100 ms, so that transmission and driving are executed 10 times for one command creation.

[0044] FIG. 5 is a flowchart illustrating the details of step S404 in FIG.

[0045] In step S501, the cell balancing control unit 106 checks whether any of the semiconductor switching elements 102 is stuck on ON based on the detection result in step S301 by the stuck-ON detection unit 105. If it is determined that there is no semiconductor switching element 102 in a stuck-ON state, the process proceeds to step S502 to perform normal cell balancing control. If it is determined that there is a semiconductor switching element 102 in a stuck-ON state, the process proceeds to step S503 to perform cell balancing control that takes the stuck-ON state into consideration.

[0046] In step S502, since there is no semiconductor switching element 102 in a stuck-ON state, the cell balancing control unit 106 performs normal cell balancing control by setting the discharge amount of each battery cell 100 so that the charge capacity of each battery cell 100 is equal. In this case, the cell balancing stop threshold described in step S406 in Fig. 4 is a small value close to 0 so that the variation in charge capacity is very small.

[0047] In step S503, the cell balancing control unit 106 checks the stuck-ON diagnosis results in order from the first semiconductor switching element BSW1 to the n-th semiconductor switching element BSWn, and obtains the number of the semiconductor switching element 102 that is stuck-ON.

[0048] In step S504, the battery cell 100 connected to the semiconductor switching element 102 adjacent to the semiconductor switching element 102 in the stuck-ON state having the number acquired in step S503 is excluded from the cell balancing target. The reason for excluding this battery cell 100 will be described later.

[0049] In step S505, the cell balancing control unit 106 sets the discharge amount of the battery cells 100 other than the battery cells 100 excluded from the cell balancing target in step S504. As described above, the battery cells 100 connected to the semiconductor switching element 102 stuck on ON continue to discharge because the discharge path shown in FIG. 2 is always available. Therefore, if the battery cells 100 are discharged so that the charge capacity of each battery cell 100 is equal, as in step S502 when the semiconductor switching element 102 is not stuck on ON, there is a problem that the discharge amount of the battery cells 100 becomes large. Therefore, in step S505, the discharge amount of each battery cell 100 is set so that the variation in charge capacity is within an allowable range. Here, "within an allowable range of the variation in charge capacity" refers to a state in which the charge capacity of each battery cell 100 is maintained so that the running of a vehicle equipped with a secondary battery is not restricted due to the variation in charge capacity (for example, the output of the secondary battery is not restricted or the output is not stopped due to the variation in charge capacity). In this case, the cell balancing stop threshold described in step S406 of Fig. 4 is almost synonymous with the range in which the variation in charge capacity described above is allowed, and a value larger than that used when the stuck-ON state of the semiconductor switching element is not detected is used. This makes it possible to prevent the amount of discharge of the battery cell 100 in the cell balancing control from becoming too large even when the stuck-ON state is detected. Then, by setting the cell balancing start threshold described in step S402 of Fig. 4 and the cell balancing stop threshold described in step S406 of Fig. 4 to values ​​that do not restrict the traveling of a vehicle equipped with a secondary battery, the distance that the vehicle can travel can be increased.

[0050] FIG. 6 is a diagram for explaining a discharge path when a semiconductor switching element adjacent to a semiconductor switching element in a stuck-ON state is turned ON.

[0051] The discharge path 600 shown in FIG. 6 is a discharge path when the third semiconductor switching element BSW3 corresponding to the third battery cell S3 is fixed ON and the semiconductor switching element BSW2 connected to the second battery cell S2 adjacent to the third battery cell S3 is turned ON. The battery cells S2 and S3 are discharged through resistors R2 and R4. At this time, the discharge amount of the battery cell S2 is greater than that when the semiconductor switching element BSW3 is not fixed ON because the voltage is doubled with the same resistance compared to when the semiconductor switching element BSW3 is not fixed ON. Furthermore, since the battery cells S3 and S2 are discharged at the same time, the variation in the charge capacity of the battery cells S3 and S2 cannot be eliminated even if the cell balancing control is performed. The same applies to the battery cell S4 adjacent to the battery cell S3 and its corresponding semiconductor switching element BSW4.

[0052] Therefore, in this embodiment, as explained in step S504 of Fig. 5, battery cells S2 and S4 adjacent to battery cell S3 are excluded from cell balancing. Specifically, in step S505, battery cells S2 and S4 excluded from cell balancing are excluded from targets for setting the discharge amount, and are not allowed to discharge. As a result, in step S405 of Fig. 4, a command to turn off semiconductor switching elements BSW2 and BSW4 is generated.

[0053] In this way, when the cell balancing control unit 106 of this embodiment detects that a semiconductor switching element 102 is stuck ON, it creates a command to execute cell balancing control while fixing, in the OFF state, the semiconductor switching elements 102 adjacent to the semiconductor switching element 102 that is stuck ON, among the semiconductor switching elements 102 connected in series to the semiconductor switching element 102 that is stuck ON. This makes it possible to reduce the amount of discharge in cell balancing control when a semiconductor switching element 102 is stuck ON.

[0054] Fig. 7 is a diagram showing the charge capacity of each battery cell when the semiconductor switching element is stuck on and the cell balancing control is stopped in a comparative example in which the cell balancing control is stopped when the semiconductor switching element is stuck on. In Fig. 7, the vertical axis is the charge capacity.

[0055] Fig. 7 shows the charge capacity 700 of each of the battery cells S1 to S4 and Sn. The battery cells 100 are used so that the charge capacity 700 of the battery cells falls within the range between the maximum usable charge capacity and the minimum usable charge capacity indicated by the dotted lines in Fig. 7. In Fig. 7, the charge capacity 700 of the battery cells is the smallest for battery cell S3 and the largest for battery cell Sn, so the variation 701 in the charge capacities corresponds to the difference between the two.

[0056] If the cell balancing control is stopped when the semiconductor switching element BSW3 is stuck ON as in the comparative example, only the battery cell S3 connected to the semiconductor switching element BSW3 in the stuck ON state continues to discharge, as shown in FIG. 7, resulting in large variation 701 in the charge capacity.

[0057] Fig. 8 is a diagram showing the charge capacity of each battery cell in the case where the cell balancing control is continued even if the semiconductor switching element is stuck ON in the charge capacity adjustment control device of the embodiment. Fig. 8 is a diagram corresponding to Fig. 7.

[0058] In contrast to the comparative example shown in Fig. 7, in the embodiment shown in Fig. 8, by performing cell balancing control even when the semiconductor switching element 102 is in a stuck-ON state, it is possible to reduce the variation 701 in the charge capacity of the battery cells 100 as shown in Fig. 8. Furthermore, by making the range in which the variation 701 in the charge capacity is allowed wider than in normal balancing control in which there is no stuck-ON state (for example, making the cell balancing stop threshold higher when the stuck-ON state of the semiconductor switching element 102 is detected than when the stuck-ON state of the semiconductor switching element 102 is not detected), it is possible to reduce the amount of discharge of the battery cells 100 compared to normal balancing control in which the amount of discharge of each battery cell 100 is set so that the charge capacity of each battery cell 100 is equal, and it is possible to increase the distance that the vehicle can travel without restrictions.

[0059] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical concept of the present invention. In addition, some or all of the configurations described in each embodiment may be combined and applied. [Explanation of symbols]

[0060] 100, S1~Sn battery cells 101, R1~Rn+1 resistor 102, BSW1 to BSWn semiconductor switching elements 103 Cell Controller 104 Charge capacity adjustment control device 105 Stuck ON detection unit 106 Cell balancing control unit 200, 600 Discharge path 700 Battery cell charge capacity 701 Charging capacity variation

Claims

1. A charge capacity adjustment control device that controls a cell controller provided with a semiconductor switching element that shorts a corresponding battery cell among a plurality of battery cells that constitute a secondary battery by switching the cell controller ON via a resistor, an ON-stuck detection unit for detecting an ON-stuck state of the semiconductor switching element; a cell balancing control unit that calculates and generates ON / OFF commands for the semiconductor switching elements to execute cell balancing control that reduces variations in charge capacity of the plurality of battery cells, The charge capacity adjustment control device is characterized in that, when it is detected that the semiconductor switching element is stuck ON, the cell balancing control unit creates the command to execute the cell balancing control by controlling the semiconductor switching elements other than the semiconductor switching element that is stuck ON.

2. In claim 1, The cell balancing control unit creates the command to execute the cell balancing control when a semiconductor switching element stuck on ON is detected, while fixing, in the OFF state, the semiconductor switching element adjacent to the semiconductor switching element stuck on ON among the semiconductor switching elements connected in series to the semiconductor switching element stuck on ON.

3. In claim 1, A charge capacity adjustment control device characterized in that the cell balancing control unit creates the command to start the cell balancing control when the variation in charge capacity of the multiple battery cells becomes equal to or greater than a cell balancing start threshold.

4. In claim 3, The cell balancing control unit generates the command to stop the cell balancing control when the variation in charge capacity of the multiple battery cells becomes smaller than a cell balancing stop threshold.

5. In claim 4, the cell balancing start threshold and the cell balancing stop threshold are values ​​at which traveling of a vehicle equipped with the secondary battery is not restricted, The cell balancing stop threshold is greater when the semiconductor switching element is detected as being stuck ON than when the semiconductor switching element is not detected as being stuck ON.

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