Cell balancing control device and cell balancing control system

Abstract

Cell balancing control device (100), comprising: an execution section (130) that performs the cell balancing control of a battery (10) including several battery cells (11); and an execution condition setting section (130) that variably sets an execution condition of the cell balancing control to increase an execution frequency of the cell balancing control according to the deterioration of the battery (10), wherein: the execution condition is a threshold value used in comparison to a measured value relating to a voltage of the battery (10), the execution section (130) performs the cell balancing control in a case where the measured value is equal to or greater than the threshold value, and the execution condition setting section (130) reduces the threshold value as the battery (10) deteriorates.

Description

Technical field

[0001] The present disclosure relates to a cell balancing control device and a cell balancing control system. State of the art

[0002] A battery installed in a vehicle, such as an electric vehicle, comprises multiple battery cells. The overall performance of such a battery may be limited if there are voltage fluctuations within individual cells. Examples include a high-voltage cell reaching the upper voltage limit of the battery during charging, and a low-voltage cell reaching the lower voltage limit of the battery sooner due to discharge or similar factors as the battery's charge level decreases.

[0003] To limit such voltage fluctuations in the individual battery cells, it is known that cell balancing control is carried out to equalize the voltage values ​​of several battery cells (see, for example, patent literature (hereinafter referred to as "PTL") 1). In particular, in a case where the difference between a maximum voltage value and a minimum voltage value of the respective battery cells is greater than a predetermined threshold, the cell balancing control is carried out by discharging battery cells with a high voltage value. List of citations from patent literature

[0004] PTL 1 Japanese patent application publication no. 2013-5677 Brief description of the invention: Technical problem

[0005] However, cell balancing control generates an energy loss, as well as a discharge rate for battery cells with a high voltage. Therefore, from an energy efficiency perspective, the number of cell balancing control units is preferably reduced as much as possible.

[0006] However, since the internal resistance of the individual battery cells increases as a battery deteriorates, the magnitude of voltage fluctuations in the individual battery cells differs depending on whether the battery is deteriorating or not. Therefore, during charging and / or discharging, the frequency with which the battery cell voltages reach an upper or lower voltage limit of the battery fluctuates, depending on the battery's state of deterioration.

[0007] In the current state of the art, the deterioration state of a battery is not taken into account, meaning that cell balancing control is always performed when there is a significant change in the condition of the individual battery cells. Consequently, the problem arises that the number of cell balancing control cycles becomes excessive, which further leads to wasteful energy loss.

[0008] One objective of the present disclosure is to provide a cell balancing control device and a cell balancing control system that are capable of optimizing the number of cell balancing control executions and preventing the occurrence of wasteful energy loss. Solution to the problem

[0009] A cell balancing control device according to the present disclosure comprises: an execution section that performs the cell balancing control of a battery including multiple battery cells; and an execution condition setting section that variably sets an execution condition of the cell balancing control in order to increase the execution frequency of the cell balancing control according to the deterioration of the battery.

[0010] A cell balancing control system according to the present disclosure comprises: a battery including several battery cells; a cell balancing circuit that balances the voltage values ​​of several battery cells; and the cell balancing control device, which performs cell balancing control by controlling the cell balancing circuit. Advantageous effects of the invention

[0011] According to the present disclosure, it is possible to optimize the number of executions of the cell balancing control and to prevent the occurrence of wasteful energy loss. List of characters Fig. Figure 1 is a block diagram of a cell balancing control system according to an embodiment of the present invention; Fig. 2A illustrates the voltage values ​​of each battery cell before charging; Fig. 2B illustrates voltage values ​​of the respective battery cells after charging in a state where battery degradation does not progress; Fig. 2C illustrates voltage values ​​of the respective battery cells after charging in a state where battery degradation is progressing; and Fig. Figure 3 is a flowchart illustrating an operational example of control by a cell balancing control device. Description of embodiments

[0012] In the following, an embodiment of the present disclosure is described in detail with reference to the drawings. Fig. Figure 1 is a block diagram of a cell balancing control system. 1 according to one embodiment of the present invention.

[0013] As in Fig. As illustrated in Figure 1, the cell balancing control system is 1 a system that is mounted on a vehicle such as an electric vehicle and a hybrid vehicle and includes cell balancing control of the battery 10 executes. The cell balancing control system 1 closes the battery 10 , the cell balancing circuit 20 and the cell balancing control device 100 a.

[0014] The battery 10is a rechargeable battery that is charged by supplying electrical energy from an external AC power supply or the like, and consists of several battery cells connected in series. 11 includes the battery cell. 11 For example, a secondary battery such as a lithium-ion battery.

[0015] The cell balancing circuit 20 is a circuit that displays the voltage values ​​of several battery cells 11 the battery 10 balances and several resistors connected in series 21 and several switches 22 includes the cells between battery cells 11 and resistances 21 are provided.

[0016] Each of the multiple switches 22 is between an upper end section of each resistor 21 and a positive electrode section of each battery cell 11provided, and is controlled by the cell balancing control device 100 switched between on and off.

[0017] If the switch 22 When switched on, the voltage of the battery cell 11 , which are connected to the aforementioned switch 22 is connected by means of resistance 21 discharged. For example, if the battery cell 11A , which is located in the second position from the top, when the switch is discharged 22A , which is the aforementioned battery cell 11A corresponds to the control of the cell balancing control device 100 switched on. The voltage of the battery cell 11A will be via resistance 21A discharged, so that in a case where the voltage value of the battery cell 11A higher than the voltage values ​​of other battery cells 11 is the voltage value of the battery cell 11Ato the voltage values ​​of other battery cells 11 is equalized. As a result, the voltage values ​​of each battery cell are adjusted. 11 balanced.

[0018] The cell balancing control device 100 It includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output circuit, all of which are not illustrated, and controls each switch. 22 the cell balancing circuit 20 based on a predefined program, the cell balancing control device thus performs 100 the battery's cell balancing control 10 out of.

[0019] The cell balancing control device 100 includes the voltage detection section 110 , the deterioration status recording section 120 and the control section 130The control section 130 corresponds to the “Execution Section” and the “Execution Conditions Setting Section” of the present disclosure.

[0020] The voltage detection section 110 records the voltage values ​​of each battery cell 11 and sends each detected voltage value to the control section 130 off. The voltage detection section 110 can determine the voltage values ​​of each battery cell 11 directly or by means of another recognition section or the like.

[0021] The recording section 120 The deterioration state detects a deterioration state of the battery. 10 and reports the deterioration state to the control section 130 off. The battery's deteriorating condition 10 For example, a ratio of the battery's internal resistance 10at a predetermined time at an internal resistance of the battery 10 In its initial state. The acquisition section. 120 The deterioration state is capable of detecting the deterioration state that is monitored by another control device or the like.

[0022] The control section 130 variably defines an execution condition for the cell balancing control in order to determine the execution frequency of the cell balancing control according to the deterioration of the battery. 10 to increase. In particular, the control section determines 130 a threshold value to execute cell balancing control based on the deterioration state of the battery 10 The threshold is a value that is compared to the amount of voltage value change between each battery cell. 11is used, and the amount of the voltage value change is a measured value that relates to a voltage of the battery. 10 refers to the amount of voltage change between each battery cell. 11 For example, it is a difference value between a maximum voltage value and a minimum voltage value of the respective voltage values.

[0023] In particular, the control section reduces 130 the threshold when the battery deteriorates 10 progresses. In this way, as will be described later, it is possible to adjust the threshold according to the battery's state of deterioration. 10 to adjust.

[0024] The control section 130 The cell balancing control is carried out according to the voltage values ​​of each battery cell 11 and the specified threshold value. For example, the control section executes 130The cell balancing control switches off in a case where the difference between the maximum voltage value and the minimum voltage value of the voltage values ​​of each battery cell 11 is equal to or greater than the threshold value. In particular, the control section controls 130 switching each switch on and off 22 , to determine the voltage values ​​of other battery cells 11 to the voltage value of the battery cell 11 to adjust the minimum voltage value. This makes it possible to adjust the cell balancing control according to the battery's deterioration state. 10 to execute.

[0025] Next, the operation of the present embodiment will be described. Fig. 2A illustrates voltage values ​​of each battery cell 11 in front of the shop. Fig. 2B illustrates voltage values ​​of each battery cell 11 after charging in a state where the battery deteriorates10 does not progress. Fig. 2C illustrates voltage values ​​of each battery cell 11 after charging in a state where the battery deteriorates 10 progresses.

[0026] It should be noted that Fig. 2A to Fig. 2C, for example, the battery 10 with five battery cells 11 to illustrate (a first cell, a second cell, a third cell, a fourth cell, and a fifth cell). Furthermore, the vertical axis indicates Fig. 2A to Fig. 2C indicates the voltage value.

[0027] As the battery deteriorates 10 The internal resistance of the battery increases 10 In a case where the internal resistance of the battery 10If the internal resistance is large, the voltage value will be higher when the same electric current flows than in a case where the internal resistance is small, so that the fluctuations in the voltage values ​​of each battery cell are different. 11 to distinguish between the point in time when the battery deteriorates 10 progresses, and as the battery deteriorates 10 does not progress.

[0028] In particular, the frequency with which the voltages of one or more battery cells change increases. 11 the battery 10 to reach an upper voltage limit or a lower voltage limit that is suitable for the battery 10 is set when the battery 10 is charged and / or discharged when the battery deteriorates 10 progresses. The upper voltage limit is a voltage value above which battery charging ceases. 10This leads to overcharging. The lower voltage limit is a voltage value above which the battery begins to discharge. 10 leads to deep discharge.

[0029] As in Fig. As illustrated in 2A, it is assumed, for example, that the voltage values ​​are in a range between a first voltage value (the maximum voltage value) and a second voltage value (the minimum voltage value) before charging the battery. 10 fluctuate. In Fig. 2A to Fig. 2C is the voltage value of the second cell, the first voltage value, and the voltage value of the third cell is the second voltage value.

[0030] In the case of a condition where the battery deteriorates 10 does not progress, as in Fig. 2B illustrates, for example, that the battery 10only is it charged to such an extent that the voltage of the second cell, at its maximum voltage value, does not reach the upper voltage limit. However, as in Fig. 2C illustrates that even in a case where the charge amount is the same as in Fig. 2B is the amount of the increase in voltage values ​​in the state where the battery deteriorates. 10 progresses greater than those in the state of Fig. 2B. This is caused by an increased internal resistance of the battery. 10 caused. As a result, it is very likely that at least the second cell with the maximum voltage value exceeds the upper voltage limit.

[0031] That means if the battery 10 As the battery is charged, the frequency with which the voltages of the battery cells change increases. 11 with a high voltage value exceeding the upper voltage limit of the battery 10to reach, with progressive deterioration of the battery 10 It should be noted that even if the battery 10 as the battery cells are discharged, the frequency with which the voltages of the battery cells change. 11 with a low voltage value the lower voltage limit of the battery 10 to reach, with progressive deterioration of the battery 10 Similarly increased.

[0032] This assumes that the threshold for executing the cell balancing control is set to a fixed value (for example, a value less than the difference between the first voltage value and the second voltage value). At this point, when the cell balancing control is executed, battery cells are 11The battery is discharged at a high voltage, whereby the voltage of the second cell is adjusted to that of the third cell, which has the minimum voltage. Consequently, even in a case where the battery... 10 as in Fig. 2C deteriorates when the battery 10 When charged, the voltage value of the second cell is adjusted to the voltage value of the third cell, so that it is possible to configure the voltage values ​​of the respective cells to not exceed the upper voltage limit.

[0033] In a case where the battery deteriorates 10 not as in Fig. As 2B progresses, on the other hand the voltage value of one of the battery cells exceeds 11 not the upper voltage limit, even if the battery 10 is being charged. Since energy loss, as well as the amount of discharged battery cells, is a factor. 11If a high voltage value is generated in the cell balancing control, the cell balancing control is preferably not implemented as far as possible from an energy efficiency point of view. However, if the threshold is set to the fixed value described above, the cell balancing control is implemented in the same way as in the case of Fig. 2C executed.

[0034] That means even in a case where the battery deteriorates 10 If the deterioration does not progress, the cell balancing control is executed in the same way as if the battery were deteriorating. 10 As the process progresses, a problem arises in that the number of cell balancing control executions becomes excessive, which further leads to wasteful energy loss.

[0035] In the present embodiment, the threshold is reduced when the battery deteriorates. 10progresses. In other words, in the present embodiment, the threshold is higher the less the battery deteriorates. 10 progresses. Accordingly, in the case of Fig. 2B The cell balancing control is no longer executed by setting the threshold value to be greater than the difference between the first voltage value and the second voltage value. This prevents the cell balancing control from being executed excessively, which further limits the occurrence of wasteful energy loss.

[0036] It should be noted that it is possible to preset values ​​for each battery deterioration state. 10 to be used as a threshold value. Furthermore, the threshold value can be appropriately adjusted to such a value through experiments, simulations and / or the like, whereby the battery performance10 due to the amount of voltage value change between each battery cell 11 is not limited.

[0037] An operational example of control by a cell balancing control device 100 , which is configured as described above, is described. Fig. Figure 3 is a flowchart that provides an example of the operation of the cell balancing control device. 100 illustrated. Processing in Fig. 3 is executed, for example, when the cell balancing control system 1 commences operations.

[0038] As in Fig. As illustrated in section 3, the control section covers 130 a deterioration state of the battery 10 (Step S101 The control section 130 then determines a threshold value to execute the cell balancing control (step S102 In particular, the control section determines 130the threshold value such that the threshold value decreases with progressive deterioration of the battery 10 is reduced.

[0039] Next, the control section records 130 Voltage values ​​of each battery cell 11 (Step S103 The control section 130 It then assesses whether a difference between a maximum voltage value and a minimum voltage value of the respective voltage values ​​is equal to or greater than the threshold value (step S104 ).

[0040] As a result of the assessment, the control ends in a case where the difference value is less than the threshold value (step S104 , NO). In a case where the difference value is equal to or greater than the threshold value (step S104 , YES), the control section 130 on the other hand, the cell balancing control (step S105 The control ends after the step S105 .

[0041] It should be noted that the control system is active during the battery charging / discharging process. 10 can be executed or can be executed separately from the charging / unloading process.

[0042] According to the present embodiment configured as described above, the threshold for executing the cell balancing control is determined according to the deterioration state of the battery. 10 determined so that the number of cell balancing control executions depends on the deterioration state of the battery. 10 This can be adjusted. As a result, it is possible to optimize the number of cell balancing control executions and limit the occurrence of wasteful energy loss.

[0043] Furthermore, the threshold is set so that it increases with progressive deterioration of the battery. 10As the battery's performance decreases, it is possible to adjust the threshold according to its state of deterioration. 10 to determine.

[0044] It should be noted that, although in the embodiment described above the execution section and the execution condition setting section are referred to as the control section 130 The present disclosure is not limited to the example shown. The execution section and the execution condition setting section can be provided separately.

[0045] Furthermore, the present disclosure is not limited to, although the cell balancing control device 100 the deterioration state of the battery 10 through the recording section 120 the deterioration state is detected in the embodiment described above. For example, the cell balancing control device can 100(the execution condition setting section) the execution condition of the cell balancing control based on the internal resistance of the battery 10 The cell balancing control device can be set variably. Furthermore, the cell balancing control device can... 100 (the execution condition setting section) the execution condition of the cell balancing control can also be set variably based on the frequency of reaching the upper voltage limit or the lower voltage limit when the battery 10 is being loaded and / or unloaded.

[0046] Although the in Fig. Although the configuration illustrated in the embodiment described above was presented as an example of a cell balancing circuit in 1, the present disclosure is not limited to this. A configuration other than that illustrated in 1 is also possible. Fig. 1 can be used as a cell balancing circuit.

[0047] Furthermore, each of the embodiments described above is merely an exemplary embodiment for implementing the present disclosure, and the technical scope of the present disclosure must not be thereby restricted. That is to say, the present disclosure can be implemented in various forms without deviating from its core or main features.

[0048] This application is based on Japanese patent application No. 2018-041859, filed on March 8, 2018, the entire contents of which are incorporated herein by reference. Commercial applicability

[0049] The cell balancing control device of the present disclosure is useful as a cell balancing control device and as a cell balancing control system that is able to optimize the number of cell balancing control implementations and limit the occurrence of wasteful energy loss. Reference symbol list 1 Cell balancing control system 10 batteries 11 battery cell 20 cell balancing circuit 21 Resistance 22 switches 100 cell balancing control unit 110 Voltage detection section 120 Deterioration status recording section 130 Control section QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2018041859

[0048]

Claims

[1] Cell balancing control device comprising: an execution section that performs the cell balancing control of a battery including multiple battery cells; and an execution condition setting section that variably sets an execution condition of the cell balancing control in order to increase the execution frequency of the cell balancing control according to the deterioration of the battery. [2] Cell balancing control device according to claim 1, wherein: The execution condition is a threshold value that is used in comparison to a measured value relating to a battery voltage. the execution section performs the cell balancing control in a case where the measured value is equal to or greater than the threshold, and The execution condition setting section reduces the threshold as the battery deteriorates. [3] Cell balancing control device according to claim 2, wherein the measured value is a difference value between a maximum voltage value and a minimum voltage value of the voltage values ​​of each of the battery cells. [4] Cell balancing control device according to claim 1, wherein the execution condition setting section variably sets the execution condition of the cell balancing control based on an internal resistance of the battery. [5] Cell balancing control device according to claim 1, wherein the execution condition setting section variably sets the execution condition of the cell balancing control based on a frequency of reaching an upper voltage limit or a lower voltage limit when the battery is charged and / or discharged. [6] Cell balancing control system, comprising: a battery including several battery cells; a cell balancing circuit that balances the voltage values ​​of several battery cells; and the cell balancing control device according to claim 1, which performs cell balancing control by controlling the cell balancing circuit.