Battery management system

Abstract

The application relates to the technical field of batteries and discloses a battery management system. The battery management system comprises a switching module, a charging and discharging module, an internal resistance detection module, an insulation detection module and a control module; the switching module is connected with a plurality of battery monomers in series in a battery pack and has a plurality of conduction states; the charging and discharging module can actively balance or pulse heat the corresponding battery monomers when the switching module is in the corresponding conduction state; the internal resistance detection module can detect the internal resistance of the corresponding battery monomers when the switching module is in the corresponding conduction state; the insulation detection module can detect the insulation of the corresponding battery monomers when the switching module is in the corresponding conduction state; and the control module is configured to set the conduction state of the switching module so that the charging and discharging module, the internal resistance detection module or the insulation detection module is connected with the corresponding battery monomers. The embodiment of the application can perform multi-dimensional monitoring and management on single battery monomers in the battery pack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and in particular to a battery management system. BACKGROUND

[0002] A vehicle-mounted power battery pack is usually composed of multiple battery monomers.

[0003] Due to the complex working conditions of the power battery pack, process differences exist in the manufacturing process of the battery monomers, and there are also differences in the cycle life of the battery monomers. Therefore, the battery monomers in the battery pack must be managed in a targeted manner.

[0004] However, the battery management system in the related art does not monitor and manage the battery monomers in multiple dimensions according to factors such as process differences and life differences of each battery monomer, which leads to an exacerbation of the uneven performance of the battery monomers of the power battery pack and affects the overall performance of the power battery pack. SUMMARY

[0005] The purpose of the present application is to provide a battery management system that can monitor and manage individual battery monomers in a battery pack in multiple dimensions, thereby avoiding an exacerbation of the uneven performance of the battery monomers of the power battery pack.

[0006] Embodiments of the present application provide a battery management system, comprising:

[0007] A switch module connected to multiple battery monomers in series in a battery pack, having multiple conduction states;

[0008] A charge-discharge module connected to the switch module, capable of actively balancing or pulse heating the corresponding battery monomers when the switch module is in the corresponding conduction state;

[0009] An internal resistance detection module connected to the switch module, capable of detecting the internal resistance of the corresponding battery monomers when the switch module is in the corresponding conduction state;

[0010] An insulation detection module connected to the switch module, capable of detecting the insulation of the corresponding battery monomers when the switch module is in the corresponding conduction state;

[0011] A control module connected to the switch module, the charge-discharge module, the internal resistance detection module, and the insulation detection module, configured to set the conduction state of the switch module to connect the charge-discharge module, the internal resistance detection module, or the insulation detection module to the corresponding battery monomers.

[0012] In some embodiments, the switch module includes multiple groups of first branches and multiple groups of second branches;

[0013] The positive electrode of the battery cell is connected to the first end of one of the first branches and the first end of one of the second branches, and the negative electrode of the battery cell is connected to the first end of the other first branch and the first end of the other second branch, the second end of the first branch is connected to the first end of the charge-discharge module, and the second end of the second branch is connected to the second end of the charge-discharge module.

[0014] The control module is connected to the first branch and the second branch and is configured to set the first branch and the second branch to be turned on or turned off and the current direction when turned on.

[0015] In some embodiments, the first branch and the second branch are both obtained by connecting two back-to-back series field effect tubes in series;

[0016] The control module is connected to the gate of the field effect tube and is configured to set the conduction state of the field effect tube to set the current direction of the current in the loop formed by the battery cell, the switch module, and the charge-discharge module.

[0017] In some embodiments, the charge-discharge module includes a first switch, a unidirectional conduction unit, a first charge-discharge unit, and a second charge-discharge unit;

[0018] The first switch, the first charge-discharge unit, and the second charge-discharge unit are connected in series, the unidirectional conduction unit is connected in parallel to the bypass of the second charge-discharge unit, and the first charge-discharge unit forms a loop with the corresponding battery cell or the first charge-discharge unit, the second charge-discharge unit, and the corresponding battery cell form a loop when the first switch is closed and the switch module is in the corresponding conduction state.

[0019] 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 loop 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 actively balance the corresponding battery cell or the first charge-discharge unit actively balances the corresponding battery cell.

[0020] In some embodiments, the internal resistance detection module includes a second switch, an internal resistance detection unit, and an energy release unit;

[0021] The second switch and the internal resistance detection unit are connected in series, the internal resistance detection unit forms a loop with the corresponding battery cell when the second switch is closed and the switch module is in the corresponding conduction state, and the energy release unit is connected in parallel to the internal resistance detection unit.

[0022] In some embodiments, the control module is configured to set the on state of the second switch, so that the internal resistance detection unit detects the internal resistance of the corresponding battery monomer, the energy release unit releases the charge in the internal resistance detection unit, and the charge-discharge module performs pulse heating on the battery monomer with the largest internal resistance.

[0023] In some embodiments, the control module is configured to calculate the internal resistance of the battery monomer according to the impedance of the internal resistance detection unit and the minimum total impedance of the internal resistance detection unit and the corresponding battery monomer forming a loop.

[0024] In some embodiments, the insulation detection module comprises 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.

[0025] The first end of the first current limiting unit is connected to the switch module through the third switch, the second end of the first current limiting unit is connected to the battery pack, the first current limiting unit forms a loop with the corresponding battery monomer when the third switch is closed and the switch module is in the corresponding on state, the first end of the second current limiting unit is connected to the switch module through the fourth switch, the second end of the second current limiting unit is connected to the battery pack, the second current limiting unit forms a loop with the corresponding battery monomer when the fourth switch is closed and the switch module is in the corresponding on state, 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.

[0026] In some embodiments, the control module is configured to set the on state of the third switch and the fourth switch and the running 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 monomer, and observe the resistance and equivalent Y capacitor value of the battery monomer according to the voltage waveform data obtained by the first voltage sampling unit and the second voltage sampling unit.

[0027] The application has the following advantages: the switch module, the charge-discharge module, the internal resistance detection module, the insulation detection module and the control module are configured, the on state of the switch module is set by the control module to connect the charge-discharge module, the internal resistance detection module or the insulation detection module to the corresponding battery monomer, the corresponding battery monomer can be actively balanced, pulse heated, internally resistance detected and insulation detected, the single battery monomer in the battery pack can be monitored and managed in multiple dimensions, and the performance difference of the battery monomers in the power battery pack is avoided from being aggravated. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of a battery management system provided by a first embodiment of the present application.

[0029] Figure 2 is a structural schematic diagram of a battery management system provided by a second embodiment of the present application. DETAILED DESCRIPTION

[0030] For the purpose of the present application, technical solutions and advantages, the following will be further described in detail in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not intended to limit the present application.

[0031] It should be noted that although the functional modules are divided in the device schematic diagram, and the logical order is shown in the flowchart, in some cases, the steps shown can be performed in a manner different from the module division in the device or the order in the flowchart. The terms "first", "second", etc. in the description and claims and drawings are used to distinguish similar objects, and are not intended to describe a specific order or sequence.

[0032] 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 the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application, and are not intended to limit the present application.

[0033] The embodiments of the present application provide a battery management system. Referring to Figure 1 In some embodiments, the battery management system includes a switching module 100, a charging and discharging module 200, an internal resistance detection module 300, an insulation detection module 400 and a control module 500.

[0034] The switching module 100 connects a plurality of battery cells in series in a battery pack, and the switching module 100 has a plurality of conduction states. Specifically, the switching module 100 connects a plurality of battery cells in the battery pack, respectively, and by being configured as different conduction states, one or more battery cells can be connected to an external circuit through the switching module 100. For example, when the switching module 100 is set to a first conduction state, the first battery cell can be connected to the external circuit while the other battery cells are not connected to the external circuit, when the switching module 100 is set to a second conduction state, the second battery cell can be connected to the external circuit while the other battery cells are not connected to the external circuit, and when the switching module 100 is set to an n-th conduction state, all battery cells can be connected to the external circuit.

[0035] The charge-discharge module 200 is connected to the switch module 100, and the charge-discharge module 200 can actively balance or pulse heat the corresponding battery cell when the switch module 100 is in the corresponding conduction state. Specifically, the charge-discharge module 200 has two charge-discharge states of external discharge and external charging. When the switch module 100 is in the corresponding conduction state, the charge-discharge module 200 is connected to the corresponding battery cell. The charge-discharge module 200 in the external discharge state discharges the corresponding battery cell and stores the electrical energy released by the battery cell. The charge-discharge module 200 in the external charging state charges the corresponding battery cell using the pre-stored electrical energy. The corresponding battery cell is discharged and / or charged to actively balance, and the corresponding battery cell is alternately charged and discharged to pulse heat.

[0036] The internal resistance detection module 300 is connected to the switch module 100, and 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 conduction state. Specifically, the internal resistance detection module 300 calculates the internal resistance of the battery cell based on Ohm's law by measuring the voltage and current response of the battery cell under alternating current (AC) or direct current (DC) conditions.

[0037] The insulation detection module 400 is connected to the switch module 100, and the insulation detection module 400 can detect the insulation of the corresponding battery cell when the switch module 100 is in the corresponding conduction state. Specifically, the insulation detection module 400 periodically samples the voltage of the battery cell in the battery pack using the unbalanced bridge method. After a plurality of sampling periods, voltage sampling data is obtained. The insulation detection is performed by identifying the voltage sampling data obtained by sampling.

[0038] The control module 500 is connected with 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 to connect the charge-discharge module 200, the internal resistance detection module 300 or the insulation detection module 400 with the corresponding battery monomer. 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 the active balancing mode, the control module 500 sets the conduction state of the switch module 100 according to the state of charge of each battery monomer. When the number of battery monomers with the maximum state of charge and the number of battery monomers with the minimum state of charge respectively reach a corresponding threshold number, the control module 500 sets the conduction state of the switch module 100 to make the charge-discharge module 200 discharge a plurality of battery monomers including the battery monomer with the maximum state of charge and store the electrical energy released by the battery monomers, and then make the charge-discharge module 200 charge a plurality of battery monomers including the battery monomer with the minimum state of charge by using the stored electrical energy. When the battery management system operates in the temperature control mode, the control module 500 sets the conduction state of the switch module 100 according to the battery temperature parameter and the internal resistance value of the battery monomer. When the battery temperature parameter of the battery monomer does not reach a preset temperature threshold parameter, the control module 500 determines the battery monomer with the maximum internal resistance value and sets the conduction state of the switch module 100 to make the charge-discharge module 200 alternately charge and discharge the battery monomer with the maximum internal resistance value. The charge-discharge module 200 first discharges the battery monomer with the maximum internal resistance value to store the electrical energy released by the battery monomer, and then charges the battery monomer with the maximum internal resistance value by using the stored electrical energy. When the battery management system operates in the insulation detection mode, the battery monomer is regarded as an insulation resistor and a Y capacitor. The control module 500 sets the conduction state of the switch module 100 to make the insulation detection module 400 periodically sample the voltage of the battery monomer in the battery pack by using the non-balance bridge method. The variable forgetting factor recursive least squares algorithm is used to process the waveform recognition of the voltage sampling data to obtain a waveform recognition result of a non-abnormal waveform or an abnormal waveform. When the waveform recognition result of the non-abnormal waveform is obtained, the variable forgetting factor recursive least squares algorithm is used to process the parameter recognition of the voltage sampling data to obtain a first parameter recognition result. When the waveform recognition result of the abnormal waveform is obtained, the parameter recognition of the steady-state region of the voltage sampling data is processed to obtain a second parameter recognition result. The first parameter recognition result or the second parameter recognition result is used as an observation quantity to estimate the state quantity of the state space model with the resistance value of the insulation resistor and the capacitance value of the Y capacitor as the state quantity to obtain the resistance estimation value of the insulation resistor and the capacitance estimation value of the Y capacitor.

[0039] By referring to Figure 1 and Figure 2In one embodiment, the switch module 100 comprises a plurality of first branches 110 and a plurality of second branches 120. The positive poles of the battery cells are connected to the first ends of the first branches 110 and the first ends of the second branches 120, respectively, and the negative poles of the battery cells are connected to the first ends of the other first branches 110 and the first ends of the other second branches 120, respectively. The second ends of the first branches 110 are connected to the first end of the charge-discharge module 200, and the second ends of the second branches 120 are connected to the second end of the charge-discharge module 200. The control module 500 is connected to the first branches 110 and the second branches 120, and is configured to set the first branches 110 and the second branches 120 to be on or off, and the current direction when the first branches 110 and the second branches 120 are on. When charging the battery cells, the control module 500 sets the second branches 120 connected to the positive poles of the battery cells at the end to be charged and the first branches 110 connected to the negative poles of the battery cells at the end to be charged to be on. For example, when charging the first battery cell, the control module 500 sets the first group of second branches 120 and the second group of first branches 110 to be on, so that the charge-discharge module 200 charges the first battery cell. When charging all the battery cells, the control module 500 sets the first group of second branches 120 and the last group of first branches 110 to be on, so that the charge-discharge module 200 charges all the battery cells. When discharging the battery cells, the control module 500 sets the first branches 110 connected to the positive poles of the battery cells at the end to be charged and the second branches 120 connected to the negative poles of the battery cells at the end to be charged to be on, or sets the second branches 120 connected to the positive poles of the battery cells at the end to be charged and the first branches 110 connected to the negative poles of the battery cells at the end to be charged to be on. For example, when discharging all the battery cells, the control module 500 sets the first group of second branches 120 and the last group of second branches 120 to be on, so that all the battery cells discharge to the charge-discharge module 200, or sets the first group of first branches 110 and the last group of second branches 120 to be on, so that all the battery cells discharge to the charge-discharge module 200.

[0040] More specifically, the first branches 110 and the second branches 120 are each obtained by connecting two field effect tubes in series back to back. The control module 500 is connected to the gates of the field effect tubes, and is configured to set the conduction state of the field effect tubes to set the current direction of the current in the loop formed by the battery cells, the switch module 100 and the charge-discharge module 200.

[0041] For further understanding of the present application, reference is made to the following Figure 1 and Figure 2In a specific embodiment, the charge-discharge module 200 comprises a first switch 210, a unidirectional conducting 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 conducting unit 220 is connected in parallel to the second charge-discharge unit 240, and the first charge-discharge unit 230 forms a loop with the corresponding battery cell or the first charge-discharge unit 230 and the second charge-discharge unit 240 form a loop with the corresponding battery cell when the first switch 210 is closed and the switch module 100 is in the corresponding conducting state. The unidirectional conducting unit 220 is a diode, the first charge-discharge unit 230 is an inductor, and the second charge-discharge unit 240 is a capacitor.

[0042] In some embodiments, the control module 500 is configured to set the conducting state of the first switch 210 and set the current direction of the current in the loop 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 actively equalize the corresponding battery cell or the first charge-discharge unit 230 actively equalizes the corresponding battery cell alone.

[0043] When the number of the battery monomers with the maximum charge level does not reach the first threshold number, the on-off state of the switch module 100 is set and the battery monomers with the maximum charge level form a loop with the charge-discharge module 200, so that the first charge-discharge unit 230 discharges the battery monomers with the maximum charge level alone and stores the electric energy released by the battery monomers. When the number of the battery monomers with the maximum charge level reaches the first threshold number, the on-off state of the switch module 100 is set and each battery monomer forms a loop with the charge-discharge module 200, so that the first charge-discharge unit 230 and the second charge-discharge unit 240 discharge each battery monomer together and store the electric energy released by the battery monomers. Specifically, the control module 500 obtains the charge level of each battery monomer in real time and compares the charge level of each battery monomer. The number of the battery monomers with the maximum charge level is determined, and the number of the battery monomers with the maximum charge level is compared with the first threshold number. When the number of the battery monomers with the maximum charge level does not reach the first threshold number, the control module 500 sets the on-off state of the switch module 100 to form a loop between the battery monomers with the maximum charge level and the charge-discharge module 200, and the first charge-discharge unit 230 discharges the battery monomers with the maximum charge level alone and stores the electric energy released by the battery monomers. When the number of the battery monomers with the maximum charge level reaches the first threshold number, the control module 500 sets the on-off state of the switch module 100 to form a loop between each battery monomer and the charge-discharge module 200, and the first charge-discharge unit 230 and the second charge-discharge unit 240 discharge each battery monomer together and store the electric energy released by the battery monomers. For example, the first threshold number is set to 2. When the number of the battery monomers with the maximum charge level does not reach 2 (i.e., the number of the battery monomers with the maximum charge level is 1), the control module 500 sets the on-off state of the switch module 100 to form a loop between the battery monomer with the maximum charge level and the charge-discharge module 200 and configures the current direction, so that the first charge-discharge unit 230 discharges the battery monomer with the maximum charge level alone and stores the electric energy released by the battery monomer. When the number of the battery monomers with the maximum charge level reaches 2 (i.e., the number of the battery monomers with the maximum charge level is 2 or more), the control module 500 sets the on-off state of the switch module 100 to form a loop between each battery monomer and 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 discharge each battery monomer together and store the electric energy released by the battery monomers.

[0044] When the number of the battery cells with the minimum charge level does not reach the second threshold number, the switch module 100 is set to the on state and the battery cells with the minimum charge level are connected to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges the battery cells with the minimum charge level using the pre-stored electrical energy. When the number of the battery cells with the minimum charge level reaches the second threshold number, the switch module 100 is set to the on state and each battery cell is connected to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges each battery cell using the pre-stored electrical energy. Specifically, the control module 500 obtains the charge levels of each battery cell in real time and compares the charge levels of each battery cell, determines the number of the battery cells with the minimum charge level, compares the number of the battery cells with the minimum charge level with the pre-set second threshold number, and after the charge-discharge module 200 discharges the battery cell with the maximum charge level, when the number of the battery cells with the minimum charge level does not reach the second threshold number, the control module 500 sets the switch module 100 to the on state to connect the battery cells with the minimum charge level to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges the battery cells with the minimum charge level using the electrical energy obtained from the battery cell with the maximum charge level. When the number of the battery cells with the minimum charge level reaches the second threshold number, the control module 500 sets the switch module 100 to the on state to connect each battery cell to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges each battery cell using the electrical energy obtained from the battery cell with the maximum charge level. For example, the second threshold number is set to 2, when the number of the battery cells with the minimum charge level does not reach 2 (i.e., the number of the battery cells with the minimum charge level is 1), the control module 500 sets the switch module 100 to the on state to connect the battery cell with the minimum charge level to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges the battery cell with the minimum charge level alone. When the number of the battery cells with the minimum charge level reaches 2 (i.e., the number of the battery cells with the minimum charge level is 2 or more), the control module 500 sets the switch module 100 to the on state to connect each battery cell to the charge-discharge module 200 to form a loop, so that the charge-discharge module 200 charges each battery cell.

[0045] In some embodiments, the control module 500 is configured to perform fuzzy inference on the first charge difference value and the second charge difference value to obtain the equalization current, and the charge-discharge module 200 discharges the battery cells including the battery cell with the maximum charge level and charges the battery cells including the battery cell with the minimum charge level using the equalization current.

[0046] Specifically, the control module 500 presets a fuzzy control table and performs fuzzy reasoning on the corresponding fuzzy control quantity in the fuzzy control table according to both the first charge difference value and the second charge difference value, so as to obtain the equalization current, and then configures the charge-discharge module 200, the switch module 100 and the battery monomers, so that the charge-discharge module 200 discharges a plurality of battery monomers including the battery monomer with the largest charge and charges a plurality of battery monomers including the battery monomer with the smallest charge at the equalization current.

[0047] wherein the first charge difference value is the difference between the charge of the battery monomer with the largest charge and the average charge of each battery monomer, and the second charge difference value is the difference between the average charge of each battery monomer and the charge of the battery monomer with the largest charge. The calculation formulae of the first charge difference value and the second charge difference value are as follows:

[0048] ,

[0049] ,

[0050] wherein, the first charge difference value, the second charge difference value, the charge of the battery monomer with the largest charge, the charge of the battery monomer with the smallest charge, the average charge of each battery monomer.

[0051] Specifically, the first charge difference value and the second charge difference value have membership intervals of 0%-100% respectively, and are divided into three intervals of small (S), medium (M) and large (L), and the maximum charge-discharge current of the equalization current I is set to 0-2A, which is divided into five intervals of very small (VS), small (S), medium (M), large (L) and very large (VL). The fuzzy control rules are shown in Table 1 below.

[0052] Table 1

[0053] [SOcΔ2(S)] [SOCA2(M)] [SOCA2(L) <!-- 6 -->]]> [SOCA1(S)] I(VS) I(S) I(M) [SOCA1(M)] I(S) I(L) I(L) [SOCL1(L)] I(M) I(L) I(VL)

[0054] The calculation formula of the equalization current is as follows:

[0055] ,

[0056] wherein, the accurate equalization current after de-fuzzification, the fuzzy set obtained by reasoning, the membership function of the fuzzy set obtained by reasoning.

[0057] In some embodiments, the control module 500 is configured to cause the charge-discharge module 200 to discharge or charge the battery cells with the equalization current when the third difference in charge reaches the threshold charge, determine whether the third difference in charge reaches the threshold charge at the end of the equalization period, and reset the on-off states of the switch module 100 according to the number of battery cells with the maximum charge and the number of battery cells with the minimum charge and enter the next equalization period if the third difference in charge reaches the threshold charge. Specifically, in one equalization period, the control module 500 obtains the charge of each battery cell in real time and calculates the third difference in charge, determines whether the third difference in charge reaches the threshold charge, and causes the charge-discharge module 200 to discharge or charge the battery cells with the equalization current when the third difference in charge reaches the threshold charge. Then, the control module 500 determines whether the third difference in charge reaches the threshold charge again, and enters the next equalization period if the third difference in charge reaches the threshold charge, and the control module 500 obtains the charge of each battery cell again and calculates the third difference in charge, and sets the on-off states of the switch module 100 according to the number of battery cells with the maximum charge and the number of battery cells with the minimum charge, so that the charge-discharge module 200 discharges or charges the battery cells with the equalization current. If the third difference in charge does not reach the threshold charge, the active equalization ends until the third difference in charge reaches the threshold charge again.

[0058] With reference to 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 a discharge unit 330. The second switch 310 and the internal resistance detection unit 320 are connected in series, and the internal resistance detection unit 320 forms a loop with the corresponding battery cell when the second switch 310 is closed and the switch module 100 is in the corresponding on-off state. The discharge unit 330 is connected in parallel with the internal resistance detection unit 320. The internal resistance detection unit 320 is formed by connecting a resistor, a capacitor, and an inductor in series, and the discharge unit 330 is a switching device.

[0059] In some embodiments, the control module 500 is configured to set the on state of the second switch 310 to enable the internal resistance detection unit 320 to detect the internal resistance of the corresponding battery cell, to enable the capacity release unit 330 to release the capacity in the internal resistance detection unit 320, and to enable the charge-discharge module 200 to pulse heat the battery cell with the largest internal resistance. Specifically, the control module 500 acquires the battery temperature parameters and the internal resistance values of the battery cells, calculates the average battery temperature parameter according to the battery temperature parameters of the battery cells, sets the on state of the switch module 100 when the average battery temperature parameter does not reach the temperature threshold parameter, and enables the battery cell with the largest internal resistance to form a loop with the charge-discharge module 200, so that the charge-discharge module 200 alternately charges and discharges the battery cell with the largest internal resistance to pulse heat the battery cell with the largest internal resistance. 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 until the average battery temperature parameter reaches the temperature threshold parameter. In this way, the battery cell with the largest internal resistance in the battery pack can be heated specifically, and the battery temperature parameter of the battery cell with the lowest temperature and / or the most severe aging in the battery pack can tend to be close to the battery temperature parameters of other battery cells in the battery pack. Specifically, in the current heating period, the temperature acquisition module acquires the battery temperature parameters of the battery cells, the internal resistance detection module 300 detects the internal resistance values of the battery cells, the control module 500 acquires the battery temperature parameters and the internal resistance values of the battery cells through the temperature acquisition module and the internal resistance detection module 300, calculates the average battery temperature parameter by averaging the battery temperature parameters of the battery cells, compares the average battery temperature parameter with the temperature threshold parameter, ends the current heating period and enters the next heating period if the average battery temperature parameter reaches the temperature threshold parameter, and sets the on state of the switch module 100 to enable the battery cell with the largest internal resistance to form a loop with the charge-discharge module 200 if the average battery temperature parameter does not reach the temperature threshold parameter, and controls the current direction of the loop formed by the battery cell with the largest internal resistance and the charge-discharge module 200 to enable the charge-discharge module 200 to alternately charge and discharge the battery cell with the largest internal resistance for a preset charging and discharging time, and enters the next heating period when the preset charging and discharging time ends.

[0060] 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 charge the battery cell with the largest internal resistance at a second pulse heating frequency. Wherein the first pulse heating frequency and the second pulse heating frequency are positively correlated with the battery temperature parameter of the battery cell when the battery temperature parameter of the battery cell is in a first temperature range, the first pulse heating frequency and the second pulse heating frequency are negatively correlated with the battery temperature parameter of the battery cell when the battery temperature parameter of the battery cell is in a second temperature range, and the maximum critical value of the first temperature range is not greater than the minimum critical value of the second temperature range. It can be understood that when the temperature is too low, charging or discharging the battery cell will have the problems of low charging efficiency and reducing the life of the battery, and the lower the temperature, the more obvious the above problems, so when the temperature is relatively lower in the low temperature environment, the first pulse heating frequency and the second pulse heating frequency are positively correlated with the battery temperature parameter of the battery cell, the charging intensity and the discharging intensity are reduced, the battery cell is slowly heated to a relatively higher temperature in the low temperature environment, which can reduce the damage to the battery cell caused by charging and discharging in the low temperature environment, and when the temperature is relatively higher in the low temperature environment, the first pulse heating frequency and the second pulse heating frequency are positively correlated with the battery temperature parameter of the battery cell, the charging intensity and the discharging intensity are increased, the battery cell is quickly heated to the target temperature, which can improve the heating speed of the battery cell. Specifically, a first temperature range and a second temperature range are preset, the temperature parameter in the first temperature range represents a relatively lower temperature in the low temperature environment, and the temperature parameter in the second temperature range represents a relatively higher temperature in the low temperature environment. It is determined whether the battery cell with the largest internal resistance 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 according to the battery cell with the largest internal resistance, so that the first pulse heating frequency and the second pulse heating frequency are positively correlated with the battery temperature parameter 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 according to the battery cell with the largest internal resistance, so that the first pulse heating frequency and the second pulse heating frequency are negatively correlated with the battery temperature parameter of the battery cell. Then the charge-discharge module 200 discharges the battery cell with the largest internal resistance at the first pulse heating frequency and charges the battery cell with the largest internal resistance at the second pulse heating frequency, and the battery cell with the largest internal resistance is alternately charged and discharged.

[0061] In some embodiments, the control module 500 is further configured to set the on state of the switch module 100 according to 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 the other battery cells, so that the charge-discharge module 200 performs alternating charging and discharging on the battery cells including the battery cell with the largest internal resistance value. It can be understood that, according to 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 the other battery cells, the battery cell with the deviation between the internal resistance value and the internal resistance value of the battery cell with the largest internal resistance value within the preset deviation interval is selected from the other battery cells, and then the battery cell with the largest internal resistance value and the selected battery cell are alternately charged and discharged, which can further improve the balancing efficiency of the battery cells. Specifically, before the battery cell with the largest internal resistance value is alternately charged and discharged, 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 the other battery cells, compares 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 the other battery cells with the 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 the other battery cells is within the preset deviation interval, if it is, the battery cell is selected, and the on state of the switch module 100 is set to make the charge-discharge module 200 alternately charge and discharge the battery cell with the largest internal resistance value and the selected battery cell.

[0062] In some embodiments, the control module 500 is further configured to set the on state of the switch module 100 according to the battery temperature parameter of the battery cell, 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 on state of the switch module 100 according to the battery temperature parameter of the battery cell, and when the battery temperature parameter of the battery cell does not reach the preset temperature threshold parameter, the control module 500 sets the on state of the switch module 100, so that the charge-discharge module 200 alternately charges and discharges each battery cell. The charge-discharge module 200 first discharges each battery cell to release the electrical energy stored in the battery cell, and then charges each battery cell using the stored electrical energy. In this way, by alternately charging and discharging each battery cell multiple times, heat energy can be generated through the internal resistance of the battery cell, so that the temperature inside each battery cell can be increased to generate heat energy.

[0063] In some embodiments, the control module 500 is further configured to obtain the battery temperature parameters of each battery cell, calculate an average battery temperature parameter according to the battery temperature parameters of each battery cell, determine whether the average battery temperature parameter reaches a temperature threshold parameter, set the on state of the switch module 100 and form a loop between each battery cell and the charge-discharge module 200 if the average battery temperature parameter does not reach the temperature threshold parameter, and make the charge-discharge module 200 perform alternating charging and discharging on each battery cell. It can be understood that the control module 500 periodically performs alternating charging and discharging on each battery cell until the average battery temperature parameter reaches the temperature threshold parameter before the average battery temperature parameter reaches the temperature threshold parameter. Thus, all battery cells in the battery pack can be heated at the same time, and the battery temperature parameters of all battery cells in the battery pack tend to approach the temperature threshold parameter. Specifically, in the current heating period, 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 obtains 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, compares the average battery temperature parameter with the temperature threshold parameter, ends the current heating period and enters the next heating period if the average battery temperature parameter reaches the temperature threshold parameter, and sets the on state of the switch module 100 to form a loop between each battery cell and the charge-discharge module 200 if the average battery temperature parameter does not reach the temperature threshold parameter, and controls the current direction of the loop formed by each battery cell and the charge-discharge module 200 to make the charge-discharge module 200 perform alternating charging and discharging on each battery cell within a preset charging and discharging time, and enters the next heating period when the preset charging and discharging time ends.

[0064] In some embodiments, the control module 500 is configured to calculate the internal resistance value of the battery cell according to the impedance of the internal resistance detection unit 320 and the minimum total impedance of the loop formed by the internal resistance detection unit 320 and the corresponding battery cell.

[0065] The formula for calculating the internal resistance value of the battery cell is:

[0066] ,

[0067] ,

[0068] wherein, R is the internal resistance value of the battery cell, Z is the minimum total impedance of the loop formed by the internal resistance detection unit 320 and the battery cell, Z0 is the impedance of the topology other than the battery cell in the loop formed by the internal resistance detection unit 320 and the battery cell, I0 is the maximum value of the oscillating current passing through the internal resistance detection unit 320, a voltage for the voltage across the capacitor in the internal resistance detection unit 320 at the time of the maximum oscillation current, a steady value for the voltage across the capacitor in the internal resistance detection unit 320.

[0069] In combination with reference to 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 through the third switch 410, the second end of the first current limiting unit 430 is connected to the electrical chassis of the battery pack, and the first current limiting unit 430 forms a loop with the corresponding battery cell when the third switch 410 is closed and the switch module 100 is in the corresponding conduction state. The first end of the second current limiting unit 440 is connected to the switch module 100 through the fourth switch 420, the second end of the second current limiting unit 440 is connected to the electrical chassis of the battery pack, and the second current limiting unit 440 forms a loop with the corresponding battery cell when the fourth switch 420 is closed and the switch module 100 is in the corresponding conduction state. 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. Among them, 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 dividing resistor and a voltage sampling resistor.

[0070] In some embodiments, the control module 500 is configured to set the conduction states of both the third switch 410 and the fourth switch 420 and the operating states 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 cell, and observe the resistance and equivalent Y capacitor value of the battery cell according to the voltage waveform data obtained by both the first voltage sampling unit 450 and the second voltage sampling unit 460.

[0071] First, the control module 500 closes the third switch 410 and connects the first current limiting unit 430 to the battery cell, and the first voltage sampling unit 450 and the second voltage sampling unit 460 sample the voltage of the battery cell to obtain first voltage waveform data. Since the equivalent Y capacitor of the positive and negative electrodes of the battery cell in series to the ground and exists, which can be represented by an exponential function that changes over time, and the expression of the first voltage waveform data is:

[0072] ,

[0073] wherein, is the first voltage waveform data, is a stable value of the first voltage waveform data, is a difference between a voltage value of the first voltage waveform data when the first current limiting unit 430 is connected and the stable value of the first voltage waveform data, is a time constant of the exponential function, and e is a natural constant, .

[0074] Then the control module 500 makes the fourth switch 420 closed and the second current limiting unit 440 connected to the battery monomer, and the first voltage sampling unit 450 and the second voltage sampling unit 460 sample the voltage of the battery monomer to obtain the second voltage waveform data, which can be expressed by an exponential function changing with time, and the expression of the second voltage waveform data is:

[0075] ,

[0076] wherein, is the second voltage waveform data, is a stable value of the first voltage waveform data, is a difference between a voltage value of the second voltage waveform data when the second current limiting unit 440 is connected and the stable value of the second voltage waveform data, is a time constant of the exponential function.

[0077] The parameters of the first voltage waveform data , and and the second voltage waveform data , and are identified by using the Gauss-Newton iterative method to obtain the corresponding parameter identification results, and then the resistance and the equivalent Y capacitor value of the battery monomer are observed according to the parameter identification results.

[0078] In summary, the battery management system provided by the embodiment of the application is configured with a switch module, a charge-discharge module, an internal resistance detection module, an insulation detection module and a control module, the on-off state of the switch module is set by the control module to connect the charge-discharge module, the internal resistance detection module or the insulation detection module to the corresponding battery monomer, the corresponding battery monomer can be actively balanced, pulsed heated, internally resistance detected and insulation detected, the single battery monomer in the battery pack can be monitored and managed in multiple dimensions, and the performance difference of the battery monomers of the power battery pack is avoided from being aggravated.

[0079] The switch module, the temperature acquisition module, the charge-discharge module, the internal resistance detection module and the control module are configured, the battery temperature parameters and the internal resistance values of each battery monomer can be collected in real time, the control module sets the conduction state of the switch module according to the battery temperature parameters and the internal resistance values of the battery monomer, the charge-discharge module alternately charges and discharges the battery monomer with the largest internal resistance value, the battery monomer is self-heated by pulse, the battery monomer to be controlled in temperature can be flexibly configured according to the battery temperature parameters and the internal resistance values of the battery monomer, the battery monomer with the largest internal resistance value is self-heated by pulse, and the battery temperature control efficiency is improved.

[0080] It should be understood that, in the present application, "at least one" refers to one or more, and "multiple" refers to two or more. "And / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, "A and / or B" can represent three cases of only A, only B and A and B existing at the same time, wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after are in an "or" relationship. "At least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, at least one 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", wherein a, b and c can be single or multiple.

[0081] The preferred embodiments of the embodiments of the present application are described above with reference to the accompanying drawings, and the scope of the rights of the embodiments of the present application is not limited by this. Any modifications, equivalent replacements and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall be within the scope of the rights of the embodiments of the present application.

Claims

1. A battery management system, characterized by, The application relates to a battery pack, which comprises the following modules: a switch module connected with a plurality of battery cells in series in a battery pack, having a plurality of conducting states; a charge-discharge module connected with the switch module, capable of actively balancing or pulse heating the corresponding battery cell when the switch module is in the corresponding conducting state; an internal resistance detection module connected with the switch module, capable of detecting the internal resistance of the corresponding battery cell when the switch module is in the corresponding conducting state; an insulation detection module connected with the switch module, capable of detecting the insulation of the corresponding battery cell when the switch module is in the corresponding conducting state; and a control module connected with the switch module, the charge-discharge module, the internal resistance detection module and the insulation detection module, configured to set the conducting state of the switch module so as to connect the charge-discharge module, the internal resistance detection module or the insulation detection module with the corresponding battery cell. The insulation detection module comprises 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 with the switch module through the third switch, the second end of the first current-limiting unit is connected with the electric chassis of the battery pack, the first current-limiting unit forms a loop with the corresponding battery cell when the third switch is closed and the switch module is in the corresponding conducting state, the first end of the second current-limiting unit is connected with the switch module through the fourth switch, the second end of the second current-limiting unit is connected with the electric chassis of the battery pack, the second current-limiting unit forms a loop with the corresponding battery cell when the fourth switch is closed and the switch module is in the corresponding conducting state, 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. The switch module comprises a plurality of groups of first branches and a plurality of groups of second branches. The positive electrode of the battery cell is connected with the first end of one of the first branches and the first end of one of the second branches, the negative electrode of the battery cell is connected with the first end of another of the first branches and the first end of another of the second branches, the second end of the first branch is connected with the first end of the charge-discharge module, and the second end of the second branch is connected with the second end of the charge-discharge module. The control module is connected with the first branch and the second branch, and is configured to set the on or off of the first branch and the second branch and the current direction when the first branch and the second branch are on. The first branch and the second branch are obtained by connecting two back-to-back series field effect tubes in series. The control module is connected with the gate of the field effect tube, and is configured to set the conducting state of the field effect tube so as to set the current direction of the current in the loop formed by the battery cell, the switch module and the charge-discharge module.

2. The battery management system of claim 1, wherein, The charge-discharge module comprises a first switch, a unidirectional conducting unit, a first charge-discharge unit and a second charge-discharge unit. ​ ​ 3. The battery management system of claim 2, wherein, ​ ​ 4. The battery management system of claim 1, wherein, ​ The first switch, the first charge-discharge unit and the second charge-discharge unit are connected in series, and the unidirectional conducting unit is connected in parallel with the bypass of the second charge-discharge unit; when the first switch is closed and the switch module is in the corresponding conducting state, the first charge-discharge unit forms a loop with the corresponding battery cell or the first charge-discharge unit, the second charge-discharge unit and the corresponding battery cell form a loop.

5. The battery management system of claim 4, wherein, The control module is configured to set the conducting state of the first switch and the current direction of the current in the loop 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 of claim 1, wherein, The internal resistance detection module comprises 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 conducting state, the internal resistance detection unit forms a loop with the corresponding battery cell, and the energy release unit is connected in parallel with the internal resistance detection unit.

7. The battery management system of claim 6, wherein, The control module is configured to set the conducting state of the second switch, so that the internal resistance detection unit performs internal resistance detection on the corresponding battery cell, the energy release unit releases the charge in the internal resistance detection unit, and the charge-discharge module performs pulse heating on the battery cell with the largest internal resistance.

8. The battery management system of claim 6, wherein, The control module is configured to calculate the internal resistance of the battery cell according to the impedance of the internal resistance detection unit and the minimum total impedance of the loop formed by the internal resistance detection unit and the corresponding battery cell.

9. The battery management system of claim 1, wherein, The control module is configured to set the conducting state of both the third switch and the fourth switch and the running 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 perform voltage sampling on the battery cell, and observe the resistance and equivalent Y capacitor capacitance value of the battery cell according to the voltage waveform data obtained by both the first voltage sampling unit and the second voltage sampling unit.

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