Battery management system

Abstract

The invention relates to the technical field of batteries, and discloses a battery management system. The battery management system comprises a switch module, a charging and discharging module, an internal resistance detection module, an insulation detection module and a control module, the switch module is connected with a plurality of battery monomers which are connected in series in the battery pack and has various conduction states; the charging and discharging module can perform active equalization or pulse heating on the corresponding single batteries when the switch module is in a corresponding conducting state; the internal resistance detection module can perform internal resistance detection on the corresponding single battery when the switch module is in a corresponding conduction state; the insulation detection module can perform insulation detection on the corresponding single battery when the switch module is in the corresponding conduction state; and the control module is configured to set the conducting state of the switch module so as to enable the charging and discharging module, the internal resistance detection module or the insulation detection module to be connected with the corresponding single batteries. According to the embodiment of the invention, multi-dimensional monitoring and management can be carried out on the single battery in the battery pack.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery management system. Background Technology

[0002] Vehicle-mounted power battery packs are typically composed of multiple battery cells.

[0003] Due to the complex operating conditions of power battery packs, the manufacturing processes of individual battery cells vary, and their cycle life also differs. Therefore, it is essential to manage the individual battery cells within the battery pack in a targeted manner.

[0004] However, the battery management system in the relevant technology does not perform multi-dimensional monitoring and management of individual battery cells based on factors such as differences in manufacturing processes and lifespans. This leads to increased performance inconsistencies among individual battery cells in the power battery pack, affecting the overall performance of the power battery pack. Summary of the Invention

[0005] The purpose of this application is to provide a battery management system that can perform multi-dimensional monitoring and management of individual battery cells in a battery pack, thereby preventing the performance inconsistencies among battery cells in a power battery pack from worsening.

[0006] This application provides a battery management system, including: The switch module connects multiple battery cells connected in series in the battery pack and has multiple conduction states; The charging and discharging module is connected to the switching module and can perform active equalization or pulse heating on the corresponding battery cells when the switching module is in the corresponding on state. An internal resistance detection module, connected to the switch module, can detect the internal resistance of the corresponding battery cell when the switch module is in the corresponding on state. An insulation detection module, connected to the switch module, can perform insulation detection on the corresponding battery cell when the switch module is in the corresponding on state. The control module, connected to the switch module, the charge / discharge module, the internal resistance detection module, and the insulation detection module, is configured to set the conduction state of the switch module so that the charge / discharge module, the internal resistance detection module, or the insulation detection module is connected to the corresponding battery cell.

[0007] In some embodiments, the switching module includes multiple sets of first branches and multiple sets of second branches; The positive terminal of the battery cell is connected to the first end of one of its first branches and the first end of one of its second branches, respectively. The negative terminal of the battery cell is connected to the first end of another first branch and the first end of another second branch, respectively. The second end of the first branch is connected to the first end of the charging and discharging module, and the second end of the second branch is connected to the second end of the charging and discharging module. The control module, connected to the first branch and the second branch, is configured to set the first branch and the second branch to be turned on or off, and the direction of the current when turned on.

[0008] In some embodiments, both the first branch and the second branch are obtained by connecting two field-effect transistors back to back in series. The control module, connected to the gate of the field-effect transistor, is configured to set the conduction state of the field-effect transistor to set the current direction of the circuit formed by the battery cell, the switching module, and the charging / discharging module.

[0009] In some embodiments, the charging and discharging module includes a first switch, a one-way conduction unit, a first charging and discharging unit, and a second charging and discharging unit; The first switch, the first charging / discharging unit, and the second charging / discharging unit are connected in series. The unidirectional conduction unit is connected across the bypass of the second charging / discharging unit. When the first switch is closed and the switch module is in the corresponding conducting state, the first charging / discharging unit and the corresponding battery cell form a circuit, or the first charging / discharging unit, the second charging / discharging unit, and the corresponding battery cell form a circuit.

[0010] In some embodiments, the control module is configured to set the conduction state of the first switch and set the current direction of the current in the circuit formed by the battery cell, the switch module and the charge / discharge module, so that the first charge / discharge unit and the second charge / discharge unit jointly perform active balancing on the corresponding battery cell or the first charge / discharge unit performs active balancing on the corresponding battery cell alone.

[0011] In some embodiments, the internal resistance detection module includes a second switch, an internal resistance detection unit, and an energy release unit; The second switch and the internal resistance detection unit are connected in series. When the second switch is closed and the switch module is in the corresponding on state, the internal resistance detection unit and the corresponding battery cell form a circuit. The energy release unit is connected in parallel with the internal resistance detection unit.

[0012] In some embodiments, the control module is configured to set the conduction state of the second switch so that the internal resistance detection unit performs internal resistance detection on the corresponding battery cell, and the energy release unit releases the charge in the internal resistance detection unit, and the charge / discharge module pulses heat the battery cell with the largest internal resistance value.

[0013] In some embodiments, the control module is configured to calculate the internal resistance value of the battery cell based on the impedance of the internal resistance detection unit and the minimum total impedance of the circuit formed by the internal resistance detection unit and the corresponding battery cell.

[0014] In some embodiments, the insulation detection module includes a third switch, a fourth switch, a first current limiting unit, a second current limiting unit, a first voltage sampling unit, and a second voltage sampling unit; The first end of the first current limiting unit is connected to the switch module through the third switch, and the second end of the first current limiting unit is connected to the battery pack chassis. When the third switch is closed and the switch module is in the corresponding conducting state, the first current limiting unit forms a circuit with the corresponding battery cell. The first end of the second current limiting unit is connected to the switch module through the fourth switch, and the second end of the second current limiting unit is connected to the battery pack chassis. When the fourth switch is closed and the switch module is in the corresponding conducting state, the second current limiting unit forms a circuit with the corresponding battery cell. The first voltage sampling unit is connected in parallel with the first current limiting unit and the second current limiting unit, and the second voltage sampling unit is connected in parallel with the second current limiting unit.

[0015] In some embodiments, the control module is configured to set the conduction state of both the third switch and the fourth switch, and the operating state of both the first current limiting unit and the second current limiting unit, so that the first voltage sampling unit and the second voltage sampling unit respectively sample the voltage of the battery cell, and observe the resistance and equivalent Y capacitance of the battery cell based on the voltage waveform data sampled by the first voltage sampling unit and the second voltage sampling unit.

[0016] The beneficial effects of this application are as follows: It is equipped with a switch module, a charge / discharge module, an internal resistance detection module, an insulation detection module, and a control module. The control module sets the conduction state of the switch module so that the charge / discharge module, internal resistance detection module, or insulation detection module can be connected to the corresponding battery cell. It can perform active balancing, pulse heating, internal resistance detection, and insulation detection on the corresponding battery cell. It can perform multi-dimensional monitoring and management of individual battery cells in the battery pack, and avoid aggravating the performance inconsistencies of battery cells in the power battery pack. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the battery management system provided in the first embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the battery management system provided in the second embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and drawings are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0022] This application provides a battery management system. See also... Figure 1 In some embodiments, the battery management system includes a switching module 100, a charging / discharging module 200, an internal resistance detection module 300, an insulation detection module 400, and a control module 500.

[0023] The switch module 100 connects multiple battery cells connected in series in the battery pack, and the switch module 100 has multiple conduction states. Specifically, the switch module 100 connects to multiple battery cells in the battery pack, and by being configured to different conduction states, one or more battery cells can be connected to an external circuit through the switch module 100. For example, when the switch module 100 is set to the first conduction state, the first battery cell can be connected to the external circuit while the other battery cells are not connected; when the switch module 100 is set to the second conduction state, the second battery cell can be connected to the external circuit while the other battery cells are not connected; and when the switch module 100 is set to the nth conduction state, all battery cells can be connected to the external circuit.

[0024] The charge / discharge module 200 is connected to the switch module 100. When the switch module 100 is in the corresponding on state, the charge / discharge module 200 can actively balance or pulse-heat the corresponding battery cells. Specifically, the charge / discharge module 200 has two charging / discharging states: external discharge and external charging. When the switch module 100 is in the corresponding on state, the charge / discharge module 200 is connected to the corresponding battery cell. In the external discharge state, the charge / discharge module 200 discharges the corresponding battery cell and stores the released electrical energy. In the external charging state, the charge / discharge module 200 uses the pre-stored electrical energy to charge the corresponding battery cell. Active balancing is achieved by discharging and / or charging the corresponding battery cells, and pulse heating is achieved by alternating charge and discharge of the corresponding battery cells.

[0025] The internal resistance detection module 300 is connected to the switch module 100. The internal resistance detection module 300 can detect the internal resistance of the corresponding battery cell when the switch module 100 is in the corresponding on state. Specifically, the internal resistance detection module 300 is based on Ohm's law and calculates the internal resistance value of the battery cell by measuring the voltage and current response of the battery cell under AC or DC conditions.

[0026] The insulation detection module 400 is connected to the switch module 100. The insulation detection module 400 can perform insulation detection on the corresponding battery cells when the switch module 100 is in the corresponding on state. Specifically, the insulation detection module 400 periodically samples the voltage of the battery cells in the battery pack using an unbalanced bridge method. After multiple sampling cycles, voltage sampling data is obtained, and insulation detection is performed by identifying the obtained voltage sampling data.

[0027] The control module 500 connects to the switch module 100, the charge / discharge module 200, the internal resistance detection module 300, and the insulation detection module 400. The control module 500 is configured to set the conduction state of the switch module 100 so that the charge / discharge module 200, internal resistance detection module 300, or insulation detection module 400 connects to the corresponding battery cell. The battery management system has an active balancing mode, a temperature control mode, and an insulation detection mode. When the battery management system operates in active balancing mode, the control module 500 sets the conduction state of the switch module 100 according to the charge capacity of each battery cell. When the number of battery cells with the highest charge capacity and the number of battery cells with the lowest charge capacity reach corresponding threshold numbers, the control module 500, by setting the conduction state of the switch module 100, causes the charge / discharge module 200 to discharge and store the released energy from several battery cells, including the battery cell with the highest charge capacity. Then, the charge / discharge module 200 uses the stored energy to charge several battery cells, including the battery cell with the lowest charge capacity. When the battery management system is operating in temperature control mode, the control module 500 sets the conduction state of the switch module 100 based on the battery temperature parameters and internal resistance values ​​of the individual battery cells. When the battery temperature parameters of the individual battery cells do not reach the preset temperature threshold parameters, the control module 500 determines the battery cell with the largest current internal resistance value and sets the conduction state of the switch module 100 to enable the charge / discharge module 200 to alternately charge and discharge the battery cell with the largest internal resistance value. The charge / discharge module 200 first stores the electrical energy released by the battery cell when discharging the battery cell with the largest internal resistance value, and then uses the stored electrical energy to charge the battery cell with the largest internal resistance value. When the battery management system operates in insulation detection mode, each battery cell is treated as an insulation resistor and a Y capacitor. The control module 500 sets the conduction state of the switch module 100, causing the insulation detection module 400 to periodically sample the voltage of each battery cell in the battery pack using an unbalanced bridge method. A variable forgetting factor recursive least squares algorithm is used to perform waveform identification processing on the voltage sampling data to obtain waveform identification results for non-abnormal or abnormal waveforms. When obtaining waveform identification results for non-abnormal waveforms, a variable forgetting factor recursive least squares algorithm is used to perform parameter identification processing on the voltage sampling data to obtain a first parameter identification result. When obtaining waveform identification results for abnormal waveforms, parameter identification processing is performed on the steady-state region of the voltage sampling data to obtain a second parameter identification result. Using the first parameter identification result or the second parameter identification result as the observation, state quantity estimation processing is performed on the state space model with the resistance value of the insulation resistor and the capacitance value of the Y capacitor as the state quantities to obtain the estimated resistance value of the insulation resistor and the estimated capacitance value of the Y capacitor.

[0028] See also Figure 1 and Figure 2In one specific embodiment, the switching module 100 includes multiple sets of first branches 110 and multiple sets of second branches 120. The positive terminal of a battery cell is connected to the first end of one first branch 110 and the first end of one second branch 120, respectively. The negative terminal of a battery cell is connected to the first end of another first branch 110 and the first end of another second branch 120, respectively. The second end of the first branch 110 is connected to the first end of the charging / discharging module 200, and the second end of the second branch 120 is connected to the second end of the charging / discharging module 200. The control module 500 is connected to the first branch 110 and the second branch 120, and the control module 500 is configured to set the first branch 110 and the second branch 120 to be turned on or off, and the direction of the current when turned on. When charging a single battery cell, the control module 500 activates the second branch 120 connected to the positive terminal of the battery cell to be charged at the end and the first branch 110 connected to the negative terminal of the battery cell to be charged at the end. For example, when charging the first battery cell, the control module 500 activates the first group of second branches 120 and the second group of first branches 110 so that the charge-discharge module 200 charges the first battery cell. When charging all battery cells, the control module 500 activates the first group of second branches 120 and the last group of first branches 110 so that the charge-discharge module 200 charges all battery cells. When discharging a single battery cell, the control module 500 turns on the first branch 110 connected to the positive terminal of the battery cell to be charged at the end and the second branch 120 connected to the negative terminal of the battery cell to be charged at the end, or the control module 500 turns on the second branch 120 connected to the positive terminal of the battery cell to be charged at the end and the first branch 110 connected to the negative terminal of the battery cell to be charged at the end. For example, when discharging all battery cells, the control module 500 turns on the first group of second branches 120 and the last group of second branches 120, so that all battery cells discharge to the charge-discharge module 200, or the control module 500 turns on the first group of first branches 110 and the last group of second branches 120, so that all battery cells discharge to the charge-discharge module 200.

[0029] More specifically, both the first branch 110 and the second branch 120 are formed by connecting two field-effect transistors back-to-back in series. The control module 500 is connected to the gate of the field-effect transistor and is configured to set the conduction state of the field-effect transistor to set the current direction of the circuit formed by the battery cell, the switching module 100 and the charging / discharging module 200.

[0030] See also Figure 1 and Figure 2In one specific embodiment, the charge / discharge module 200 includes a first switch 210, a unidirectional conduction unit 220, a first charge / discharge unit 230, and a second charge / discharge unit 240. The first switch 210, the first charge / discharge unit 230, and the second charge / discharge unit 240 are connected in series. The unidirectional conduction unit 220 is connected across the bypass of the second charge / discharge unit 240. When the first switch 210 is closed and the switch module 100 is in the corresponding conducting state, the first charge / discharge unit 230 forms a circuit with the corresponding battery cell, or the first charge / discharge unit 230, the second charge / discharge unit 240, and the corresponding battery cell form a circuit. The unidirectional conduction unit 220 is a diode, the first charge / discharge unit 230 is an inductor, and the second charge / discharge unit 240 is a capacitor.

[0031] In some embodiments, the control module 500 is configured to set the conduction state of the first switch 210 and set the current direction of the current in the circuit formed by the battery cell, the switch module 100 and the charge / discharge module 200, so that the first charge / discharge unit 230 and the second charge / discharge unit 240 jointly perform active balancing on the corresponding battery cell or the first charge / discharge unit 230 performs active balancing on the corresponding battery cell alone.

[0032] When the number of battery cells with the largest charge has not reached the first threshold number, the switch module 100 is turned on and the battery cell with the largest charge forms a circuit with the charge-discharge module 200, so that the first charge-discharge unit 230 discharges the battery cell with the largest charge and stores the electrical energy released by the battery cell. When the number of battery cells with the largest charge reaches the first threshold number, the switch module 100 is turned on and each battery cell forms a circuit with the charge-discharge module 200, so that the first charge-discharge unit 230 and the second charge-discharge unit 240 discharge each battery cell together and store the electrical energy released by the battery cell. Specifically, the control module 500 acquires the charge of each battery cell in real time and compares the charge of each battery cell to determine the number of battery cells with the largest charge. The number of battery cells with the largest charge is compared with a preset first threshold number. When the number of battery cells with the largest charge has not reached the first threshold number, the control module 500 sets the conduction state of the switch module 100 to enable the battery cells with the largest charge to form a circuit with the charge-discharge module 200, and enables the first charge-discharge unit 230 to discharge the battery cells with the largest charge individually and store the released energy. When the number of battery cells with the largest charge reaches the first threshold number, the control module 500 sets the conduction state of the switch module 100 to enable each battery cell to form a circuit with the charge-discharge module 200, and enables the first charge-discharge unit 230 and the second charge-discharge unit 240 to discharge each battery cell and store the released energy. For example, if the first threshold number is set to 2, when the number of battery cells with the largest charge is less than 2 (i.e., the number of battery cells with the largest charge is 1), the control module 500 sets the conduction state of the switch module 100 to enable the battery cell with the largest charge to form a circuit with the charge / discharge module 200 and configures the current direction, so that the first charge / discharge unit 230 discharges the battery cell with the largest charge alone and stores the electrical energy released by the battery cell. When the number of battery cells with the largest charge reaches 2 (i.e., the number of battery cells with the largest charge is 2 or more), the control module 500 sets the conduction state of the switch module 100 to enable each battery cell to form a circuit with the charge / discharge module 200 and configures the current direction, so that the first charge / discharge unit 230 and the second charge / discharge unit 240 jointly discharge each battery cell and store the electrical energy released by the battery cell.

[0033] When the number of battery cells with the lowest charge has not reached the second threshold number, the switch module 100 is turned on and the battery cell with the lowest charge forms a circuit with the charge / discharge module 200, so that the charge / discharge module 200 can use the pre-stored electrical energy to charge the battery cell with the lowest charge. When the number of battery cells with the lowest charge reaches the second threshold number, the switch module 100 is turned on and each battery cell forms a circuit with the charge / discharge module 200, so that the charge / discharge module 200 can use the pre-stored electrical energy to charge each battery cell. Specifically, the control module 500 acquires the charge of each battery cell in real time and compares the charge of each battery cell. It then determines the number of battery cells with the lowest charge and compares this number with a preset second threshold. After the charging / discharging module 200 discharges the battery cell with the highest charge, if the number of battery cells with the lowest charge has not reached the second threshold, the control module 500 sets the switch module 100 to be on, allowing the battery cells with the lowest charge to form a circuit with the charging / discharging module 200. This allows the charging / discharging module 200 to use the energy obtained from the battery cells with the highest charge to charge the battery cells with the lowest charge. When the number of battery cells with the lowest charge reaches the second threshold, the control module 500 sets the switch module 100 to be on, allowing each battery cell to form a circuit with the charging / discharging module 200. This allows the charging / discharging module 200 to use the energy obtained from the battery cells with the highest charge to charge each battery cell. For example, if the second threshold number is set to 2, when the number of battery cells with the smallest charge is less than 2 (i.e., the number of battery cells with the smallest charge is 1), the control module 500 sets the conduction state of the switch module 100 to make the battery cell with the smallest charge form a circuit with the charging and discharging module 200, so that the charging and discharging module 200 charges the battery cell with the smallest charge alone. When the number of battery cells with the smallest charge reaches 2 (i.e., the number of battery cells with the smallest charge is 2 or more), the control module 500 sets the conduction state of the switch module 100 to make each battery cell form a circuit with the charging and discharging module 200, so that the charging and discharging module 200 charges each battery cell.

[0034] In some embodiments, the control module 500 is configured to perform fuzzy reasoning based on a first charge difference and a second charge difference to obtain an equalization current, so that the charge-discharge module 200 discharges a number of battery cells, including the battery cell with the largest charge, and charges a number of battery cells, including the battery cell with the smallest charge, with the equalization current.

[0035] Specifically, the control module 500 presets a fuzzy control table and performs fuzzy inference based on the fuzzy control quantities corresponding to the first charge difference and the second charge difference in the fuzzy control table to obtain a balanced current. Then, by configuring the charging and discharging module 200, the switching module 100, and the battery cells, the charging and discharging module 200 discharges several battery cells, including the battery cell with the largest charge, and charges several battery cells, including the battery cell with the smallest charge, with a balanced current.

[0036] The first charge difference is the difference between the charge of the battery cell with the largest charge and the average charge of all battery cells. The second charge difference is the difference between the average charge of all battery cells and the charge of the battery cell with the largest charge. The formulas for calculating the first and second charge differences are as follows: , , in, This is the first charge difference. This is the second charge difference. This refers to the charge capacity of the battery cell with the largest charge capacity. The charge of the battery cell with the smallest charge capacity. This represents the average charge capacity of each individual battery cell.

[0037] Specifically, the first charge difference Second charge difference The membership ranges for both are 0% to 100%, divided into three intervals: small (S), medium (M), and large (L). The maximum charging and discharging current of the equalization current I is set to 0 to 2A, divided into five intervals: extremely small (VS), small (S), medium (M), large (L), and extremely large (VL). The fuzzy control rules are shown in Table 1 below.

[0038] Table 1 <![CDATA[SOCΔ2(S)]]> <![CDATA[SOCΔ2(M)]]> <![CDATA[SOCΔ2(L) <!-- 6 -->]]> <![CDATA[SOCΔ1(S)]]> I(VS) I(S) I(M) <![CDATA[SOCΔ1(M)]]> I(S) I(L) I(L) <![CDATA[SOCΔ1(L)]]> I(M) I(L) I(VL) The formula for calculating the balancing current is: , in, To achieve accurate equalization of the current after defuzzification, For the fuzzy set obtained through reasoning, is the membership function of the fuzzy set obtained through reasoning.

[0039] In some embodiments, the control module 500 is configured to, when the third charge difference reaches a threshold charge level, cause the charge / discharge module 200 to discharge or charge the battery cells with an equalization current. At the end of the equalization cycle, it determines whether the third charge difference has reached the threshold charge level. If it has, it resets the conduction state of the switch module 100 based on the number of battery cells with the highest charge level and the number of battery cells with the lowest charge level, and enters the next equalization cycle. The third charge difference is the difference between the charge level of the battery cell with the highest charge level and the charge level of the battery cell with the lowest charge level. Specifically, within one balancing cycle, the control module 500 acquires the charge capacity of each battery cell in real time and calculates the third charge difference. It then determines whether the third charge difference reaches a threshold charge capacity. When the third charge difference reaches the threshold charge capacity, the controller sets the conduction state of the switch module 100 based on the number of battery cells with the highest and lowest charge capacities. This allows the charge / discharge module 200 to discharge several battery cells, including those with the highest charge capacity and those with the lowest charge capacity, using a balancing current. Then, it again determines whether the third charge difference has reached the threshold charge capacity. If the threshold charge level is reached, the next balancing cycle begins. The control module 500 reacquires the charge level of each battery cell and calculates the third charge difference. Based on the number of battery cells with the highest charge level and the number of battery cells with the lowest charge level, the switch module 100 is set to conduct, so that the charge / discharge module 200 discharges several battery cells, including the battery cell with the highest charge level and several battery cells, including the battery cell with the lowest charge level, with a balancing current. If the threshold charge level is not reached, the active balancing ends, until the third charge difference reaches the threshold charge level again.

[0040] See also Figure 1 and Figure 2 In one specific embodiment, the internal resistance detection module 300 includes a second switch 310, an internal resistance detection unit 320, and an energy release unit 330. The second switch 310 and the internal resistance detection unit 320 are connected in series. When the second switch 310 is closed and the switch module 100 is in the corresponding on state, the internal resistance detection unit 320 forms a circuit with the corresponding battery cell. The energy release unit 330 is connected in parallel with the internal resistance detection unit 320. The internal resistance detection unit 320 is composed of a resistor, a capacitor, and an inductor connected in series, and the energy release unit 330 is a switching device.

[0041] In some embodiments, the control module 500 is configured to set the second switch 310 to an on state, so that the internal resistance detection unit 320 detects the internal resistance of the corresponding battery cell, the energy release unit 330 releases the charge in the internal resistance detection unit 320, and the charge / discharge module 200 pulse-heats the battery cell with the largest internal resistance. Specifically, the control module 500 acquires the battery temperature parameters and internal resistance values ​​of each battery cell, calculates the average battery temperature parameter based on the battery temperature parameters of each battery cell, and sets the switch module 100 to an on state when the average battery temperature parameter has not reached the temperature threshold parameter, so that the battery cell with the largest internal resistance value forms a circuit with the charge / discharge module 200, and the charge / discharge module 200 alternately charges and discharges the battery cell with the largest internal resistance value to pulse-heat the battery cell with the largest internal resistance value. Before the average battery temperature parameter reaches the temperature threshold parameter, the control module 500 periodically alternately charges and discharges the battery cell with the largest internal resistance value until the average battery temperature parameter reaches the temperature threshold parameter. Therefore, the battery cells with the highest internal resistance in the battery pack can be heated in a targeted manner, so that the battery temperature parameters of the battery cells with the lowest temperature and / or more severe aging in the battery pack tend to be close to the battery temperature parameters of other battery cells in the battery pack. Specifically, during the current heating cycle, the temperature acquisition module acquires the temperature of each battery cell and obtains the battery temperature parameters of each battery cell. The internal resistance detection module 300 detects the internal resistance of each battery cell and obtains the internal resistance value of each battery cell. The control module 500 obtains the battery temperature parameters and internal resistance values ​​of each battery cell through the temperature acquisition module and the internal resistance detection module 300. It calculates the average battery temperature parameter by averaging the battery temperature parameters of each battery cell and obtains the average battery temperature parameter. The average battery temperature parameter is compared with the temperature threshold parameter. If the average battery temperature parameter reaches the temperature threshold parameter, the current heating cycle ends and the next heating cycle begins. If the average battery temperature parameter does not reach the temperature threshold parameter, the switch module 100 is set to be on so that the battery cell with the largest current internal resistance value forms a circuit with the charge / discharge module 200. The current direction of the circuit formed by the battery cell with the largest current internal resistance value and the charge / discharge module 200 is controlled so that the charge / discharge module 200 alternately charges and discharges the battery cell with the largest current internal resistance value within a preset charge / discharge duration. The next heating cycle begins when the preset charge / discharge duration ends.

[0042] In some embodiments, the control module 500 is further configured to cause the charge / discharge module 200 to discharge the battery cell with the largest internal resistance at a first pulse heating frequency and to charge the battery cell with the largest internal resistance at a second pulse heating frequency. The first and second pulse heating frequencies are positively correlated with the battery temperature parameters of the battery cell when the battery temperature parameters are within a first temperature range, and negatively correlated with the battery temperature parameters of the battery cell when the battery temperature parameters are within a second temperature range. The maximum critical value of the first temperature range is not greater than the minimum critical value of the second temperature range. It is understandable that charging or discharging a battery cell at excessively low temperatures can lead to low charging efficiency and reduced battery life, with these problems becoming more pronounced at lower temperatures. Therefore, in relatively low-temperature environments, making the first and second pulse heating frequencies positively correlated with the battery cell's temperature parameters, reducing the charging and discharging intensity, allows the battery cell to slowly heat up to a relatively higher low-temperature environment, thus reducing damage to the battery cell caused by charging and discharging at low temperatures. Conversely, in relatively high-temperature environments, making the first and second pulse heating frequencies positively correlated with the battery cell's temperature parameters, increasing the charging and discharging intensity, allows the battery cell to heat up to the target temperature quickly, thus improving the heating rate of the battery cell. Specifically, a first temperature range and a second temperature range are preset. The temperature parameters in the first temperature range represent a relatively lower low-temperature environment, and the temperature parameters in the second temperature range represent a relatively higher low-temperature environment. It is determined whether the battery cell with the largest internal resistance value is in the first temperature range or the second temperature range. If it is in the first temperature range, the corresponding first pulse heating frequency and second pulse heating frequency are determined based on the battery cell with the largest internal resistance value, so that the first pulse heating frequency and second pulse heating frequency are positively correlated with the battery temperature parameters of the battery cell. If it is in the second temperature range, the corresponding first pulse heating frequency and second pulse heating frequency are determined based on the battery cell with the largest internal resistance value, so that the first pulse heating frequency and second pulse heating frequency are negatively correlated with the battery temperature parameters of the battery cell. Then, the charging and discharging module 200 discharges the battery cell with the largest internal resistance value at the first pulse heating frequency and charges the battery cell with the largest internal resistance value at the second pulse heating frequency, and alternately charges and discharges the battery cell with the largest internal resistance value.

[0043] In some embodiments, the control module 500 is further configured to set the conduction state of the switch module 100 based on the degree of deviation between the internal resistance value of the battery cell with the largest internal resistance value and the internal resistance values ​​of other battery cells, so that the charge / discharge module 200 alternately charges and discharges several battery cells, including the battery cell with the largest internal resistance value. It can be understood that by selecting battery cells from among the other battery cells whose internal resistance value deviates from the internal resistance value of the battery cell with the largest internal resistance value within a preset deviation range, and then alternately charging and discharging the battery cell with the largest internal resistance value and the selected battery cell, the equalization efficiency of the battery cells can be further improved. Specifically, before alternating charging and discharging the battery cell with the largest internal resistance value, the control module 500 first determines the degree of deviation between the internal resistance value of the battery cell with the largest internal resistance value and the internal resistance values ​​of other battery cells. The internal resistance deviation value between the internal resistance value of the battery cell with the largest internal resistance value and the internal resistance values ​​of other battery cells is compared with a preset deviation value to determine whether the internal resistance deviation value between the internal resistance value of the battery cell with the largest internal resistance value and the internal resistance values ​​of other battery cells is within the preset deviation range. If it is, the battery cell is selected, and by setting the conduction state of the switch module 100, the charging and discharging module 200 alternately charges and discharges the battery cell with the largest internal resistance value and the selected battery cell.

[0044] In some embodiments, the control module 500 is further configured to set the conduction state of the switch module 100 according to the battery temperature parameters of the individual battery cells, so that the charge / discharge module 200 alternately charges and discharges each battery cell to perform pulse self-heating on each battery cell. Specifically, the control module 500 sets the conduction state of the switch module 100 according to the battery temperature parameters of the individual battery cells. When the battery temperature parameters of the individual battery cells do not reach the preset temperature threshold parameter, the control module 500 sets the conduction state of the switch module 100 to allow the charge / discharge module 200 to alternately charge and discharge each battery cell. The charge / discharge module 200 first stores the electrical energy released by each battery cell during discharge, and then uses the stored electrical energy to charge each battery cell. In this way, by repeatedly alternatingly charging and discharging each battery cell, heat energy is generated through the internal resistance of the battery cells, which can raise the internal temperature of each battery cell, thereby generating heat energy.

[0045] In some embodiments, the control module 500 is further configured to acquire the battery temperature parameters of each individual battery cell, calculate the average battery temperature parameter based on the battery temperature parameters of each individual battery cell, determine whether the average battery temperature parameter has reached a temperature threshold parameter, and if not, set the switching module 100 to an on state and form a circuit between each battery cell and the charging / discharging module 200, so that the charging / discharging module 200 alternately charges and discharges each battery cell. It can be understood that before the average battery temperature parameter reaches the temperature threshold parameter, the control module 500 periodically alternately charges and discharges each battery cell until the average battery temperature parameter reaches the temperature threshold parameter. Therefore, all battery cells in the battery pack can be heated simultaneously, causing the battery temperature parameters of all battery cells in the battery pack to approach the temperature threshold parameter. Specifically, during the current heating cycle, the temperature acquisition module acquires the temperature of each battery cell and obtains the battery temperature parameters of each battery cell. The control module 500 acquires the battery temperature parameters of each battery cell through the temperature acquisition module, calculates the average battery temperature parameter by averaging the battery temperature parameters of each battery cell, and compares the average battery temperature parameter with the temperature threshold parameter. If the average battery temperature parameter reaches the temperature threshold parameter, the current heating cycle ends and the next heating cycle begins. If the average battery temperature parameter does not reach the temperature threshold parameter, the switch module 100 is set to be in the on state so that each battery cell forms a circuit with the charge / discharge module 200. The current direction of the circuit formed by each battery cell and the charge / discharge module 200 is controlled so that the charge / discharge module 200 alternately charges and discharges each battery cell within a preset charge / discharge duration. The next heating cycle begins when the preset charge / discharge duration ends.

[0046] In some embodiments, the control module 500 is configured to calculate the internal resistance value of a battery cell based on the impedance of the internal resistance detection unit 320 and the minimum total impedance of the circuit formed by the internal resistance detection unit 320 and the corresponding battery cell.

[0047] The formula for calculating the internal resistance of a single battery cell is: , , in, This refers to the internal resistance value of a single battery cell. The minimum total impedance for the circuit formed by the internal resistance detection unit 320 and the battery cell. The impedance of the topology outside the battery cell in the circuit formed by the internal resistance detection unit 320 and the battery cell. This represents the maximum value of the oscillation current passing through the internal resistance detection unit 320. This is the voltage across the capacitor in the internal resistance detection unit 320 when the oscillation current is at its maximum. This is the stable value of the voltage across the capacitor in the internal resistance detection unit 320.

[0048] See also Figure 1 and Figure 2 In one specific embodiment, the insulation detection module 400 includes a third switch 410, a fourth switch 420, a first current limiting unit 430, a second current limiting unit 440, a first voltage sampling unit 450, and a second voltage sampling unit 460. The first end of the first current limiting unit 430 is connected to the switch module 100 via the third switch 410, and the second end of the first current limiting unit 430 is connected to the battery pack's chassis. When the third switch 410 is closed and the switch module 100 is in the corresponding conducting state, the first current limiting unit 430 forms a circuit with the corresponding battery cell. The first end of the second current limiting unit 440 is connected to the switch module 100 via the fourth switch 420, and the second end of the second current limiting unit 440 is connected to the battery pack's chassis. When the fourth switch 420 is closed and the switch module 100 is in the corresponding conducting state, the second current limiting unit 440 forms a circuit with the corresponding battery cell. The first voltage sampling unit 450 is connected in parallel with the first current limiting unit 430 and the second current limiting unit 440, and the second voltage sampling unit 460 is connected in parallel with the second current limiting unit 440. The first current limiting unit 430 and the second current limiting unit 440 are each composed of a current limiting resistor and a switching device, and the first voltage sampling unit 450 and the second voltage sampling unit 460 are each composed of a voltage divider resistor and a voltage sampling resistor.

[0049] In some embodiments, the control module 500 is configured to set the conduction state of both the third switch 410 and the fourth switch 420 and the operating state of both the first current limiting unit 430 and the second current limiting unit 440, so that the first voltage sampling unit 450 and the second voltage sampling unit 460 respectively sample the voltage of the battery cells, and observe the resistance and equivalent Y capacitance of the battery cells based on the voltage waveform data sampled by the first voltage sampling unit 450 and the second voltage sampling unit 460.

[0050] First, the control module 500 closes the third switch 410 and connects the first current limiting unit 430 to the battery cell. The first voltage sampling unit 450 and the second voltage sampling unit 460 sample the voltage of the battery cell to obtain the first voltage waveform data. This is because the equivalent Y capacitance of the positive and negative terminals of the series-connected battery cell to ground... and Its existence can be represented using an exponential function that changes over time. The expression for the first voltage waveform data is as follows: , in, This is the first voltage waveform data. This represents the stationary value of the first voltage waveform data. The difference between the voltage value of the first voltage waveform data and the stable value of the first voltage waveform data when the first current limiting unit 430 is connected. for The time constant, e is the natural constant. .

[0051] Then, the control module 500 closes the fourth switch 420 and connects the second current limiting unit 440 to the battery cell. The first voltage sampling unit 450 and the second voltage sampling unit 460 sample the voltage of the battery cell to obtain the second voltage waveform data, which can be represented by an exponential function that changes with time. The expression for the second voltage waveform data is as follows: , in, This is the second voltage waveform data. This represents the stationary value of the first voltage waveform data. The difference between the voltage value of the second voltage waveform data and the stable value of the second voltage waveform data when the second current limiting unit 440 is connected. for The time constant.

[0052] The first voltage waveform data was analyzed using the Gauss-Newton iteration method. , and and the second voltage waveform data , and Parameter identification is performed and the corresponding parameter identification results are obtained. Then, the resistance and equivalent Y capacitance of the battery cells are observed based on the parameter identification results.

[0053] In summary, the battery management system provided in this application embodiment is configured with a switching module, a charging / discharging module, an internal resistance detection module, an insulation detection module, and a control module. The control module sets the conduction state of the switching module to connect the charging / discharging module, the internal resistance detection module, or the insulation detection module to the corresponding battery cell. It can perform active balancing, pulse heating, internal resistance detection, and insulation detection on the corresponding battery cell. It can perform multi-dimensional monitoring and management of individual battery cells in the battery pack, and avoid exacerbating the performance inconsistencies among battery cells in the power battery pack.

[0054] Equipped with a switching module, temperature acquisition module, charging / discharging module, internal resistance detection module, and control module, it can collect the battery temperature parameters and internal resistance values ​​of each battery cell in real time. The control module sets the conduction state of the switching module based on the battery temperature parameters and internal resistance values ​​of each battery cell, so that the charging / discharging module alternately charges and discharges the battery cell with the highest internal resistance value to perform pulse self-heating on that battery cell. It can flexibly configure the battery cells to be temperature controlled based on their battery temperature parameters and internal resistance values, and perform pulse self-heating on the battery cell with the highest internal resistance value to improve battery temperature control efficiency.

[0055] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0056] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A battery management system, characterized in that, include: The switch module connects multiple battery cells connected in series in the battery pack and has multiple conduction states; The charging and discharging module is connected to the switching module and can perform active equalization or pulse heating on the corresponding battery cells when the switching module is in the corresponding on state. An internal resistance detection module, connected to the switch module, can detect the internal resistance of the corresponding battery cell when the switch module is in the corresponding on state. An insulation detection module, connected to the switch module, can perform insulation detection on the corresponding battery cell when the switch module is in the corresponding on state. The control module, connected to the switch module, the charge / discharge module, the internal resistance detection module, and the insulation detection module, is configured to set the conduction state of the switch module so that the charge / discharge module, the internal resistance detection module, or the insulation detection module is connected to the corresponding battery cell.

2. The battery management system according to claim 1, characterized in that, The switch module includes multiple sets of first branches and multiple sets of second branches; The positive terminal of the battery cell is connected to the first end of one of its first branches and the first end of one of its second branches, respectively. The negative terminal of the battery cell is connected to the first end of another first branch and the first end of another second branch, respectively. The second end of the first branch is connected to the first end of the charging and discharging module, and the second end of the second branch is connected to the second end of the charging and discharging module. The control module, connected to the first branch and the second branch, is configured to set the first branch and the second branch to be turned on or off, and the direction of the current when turned on.

3. The battery management system according to claim 2, characterized in that, Both the first branch and the second branch are obtained by connecting two field-effect transistors back to back in series. The control module, connected to the gate of the field-effect transistor, is configured to set the conduction state of the field-effect transistor to set the current direction of the circuit formed by the battery cell, the switching module, and the charging / discharging module.

4. The battery management system according to claim 1, characterized in that, The charging and discharging module includes a first switch, a unidirectional conduction unit, a first charging and discharging unit, and a second charging and discharging unit; The first switch, the first charging / discharging unit, and the second charging / discharging unit are connected in series. The unidirectional conduction unit is connected across the bypass of the second charging / discharging unit. When the first switch is closed and the switch module is in the corresponding conducting state, the first charging / discharging unit and the corresponding battery cell form a circuit, or the first charging / discharging unit, the second charging / discharging unit, and the corresponding battery cell form a circuit.

5. The battery management system according to claim 4, characterized in that, The control module is configured to set the conduction state of the first switch and the current direction of the circuit formed by the battery cell, the switch module and the charge / discharge module, so that the first charge / discharge unit and the second charge / discharge unit jointly perform active balancing on the corresponding battery cell or the first charge / discharge unit performs active balancing on the corresponding battery cell alone.

6. The battery management system according to claim 1, characterized in that, The internal resistance detection module includes a second switch, an internal resistance detection unit, and an energy release unit; The second switch and the internal resistance detection unit are connected in series. When the second switch is closed and the switch module is in the corresponding on state, the internal resistance detection unit and the corresponding battery cell form a circuit. The energy release unit is connected in parallel with the internal resistance detection unit.

7. The battery management system according to claim 6, characterized in that, The control module is configured to set the conduction state of the second switch so that the internal resistance detection unit can detect the internal resistance of the corresponding battery cell, the energy release unit can release the charge in the internal resistance detection unit, and the charge / discharge module can pulse heat the battery cell with the largest internal resistance value.

8. The battery management system according to claim 6, characterized in that, The control module is configured to calculate the internal resistance value of the battery cell based on the impedance of the internal resistance detection unit and the minimum total impedance of the circuit formed by the internal resistance detection unit and the corresponding battery cell.

9. The battery management system according to claim 1, characterized in that, The insulation detection module includes a third switch, a fourth switch, a first current limiting unit, a second current limiting unit, a first voltage sampling unit, and a second voltage sampling unit; The first end of the first current limiting unit is connected to the switch module through the third switch, and the second end of the first current limiting unit is connected to the battery pack chassis. When the third switch is closed and the switch module is in the corresponding conducting state, the first current limiting unit forms a circuit with the corresponding battery cell. The first end of the second current limiting unit is connected to the switch module through the fourth switch, and the second end of the second current limiting unit is connected to the battery pack chassis. When the fourth switch is closed and the switch module is in the corresponding conducting state, the second current limiting unit forms a circuit with the corresponding battery cell. The first voltage sampling unit is connected in parallel with the first current limiting unit and the second current limiting unit, and the second voltage sampling unit is connected in parallel with the second current limiting unit.

10. The battery management system according to claim 9, characterized in that, The control module is configured to set the conduction state of the third switch and the fourth switch, as well as the operating state of the first current limiting unit and the second current limiting unit, so that the first voltage sampling unit and the second voltage sampling unit respectively sample the voltage of the battery cell, and observe the resistance and equivalent Y capacitance of the battery cell based on the voltage waveform data sampled by the first voltage sampling unit and the second voltage sampling unit.

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