Battery active equalization and battery impedance spectrum detection system and method

Abstract

The invention discloses a battery active equalization and battery impedance spectrum detection system and method, the system comprises a control module, a plurality of battery modules and a passive device, the control module is connected with each battery module and the passive device, each battery module is connected in series and then is connected with the passive device in parallel, and when the system works in an equalization mode, the passive device is connected with the control module. Active equalization among the battery modules and among the batteries in the battery modules can be realized; when the system works in an impedance spectrum detection mode, excitation current required by impedance spectrum measurement is generated on the battery module by controlling electric energy exchange between the battery module and the passive device, and then measurement and calculation of the impedance spectrum are realized through a current acquisition unit, an impedance spectrum measurement unit and a control unit in the battery module. According to the battery active equalization and battery impedance spectrum detection system and method disclosed by the invention, battery active equalization and battery impedance spectrum detection can be realized through time division multiplexing, and the performance of a battery management system is optimized.

Description

Technical Field

[0001] The present invention belongs to the field of battery balancing and battery impedance spectrum detection, and more specifically, relates to a battery active balancing and battery impedance spectrum detection system and method. Background Art

[0002] The battery management system (BMS) is crucial to the overall performance and safety of the battery system. The main functions of the existing battery management system include battery voltage and current data monitoring, balancing management, status monitoring and safety protection.

[0003] Differences in battery manufacturing and operating environments lead to inconsistencies between individual batteries in a battery system. Typically, hundreds or thousands of batteries are connected in series and in parallel to build a battery system to meet the voltage and capacity requirements of the load. However, battery inconsistency can lead to an imbalance in battery voltage and capacity during the charging and discharging process of the battery system, and charging or discharging batteries outside the battery's allowed voltage range can cause battery damage or even lead to safety accidents. Therefore, the battery management system needs to have a battery balancing function to compensate for the voltage and capacity imbalance between batteries so that the energy of the battery system can be fully utilized.

[0004] The basic balancing topology can be divided into two categories: passive balancing and active balancing. Passive balancing, also known as energy-consuming balancing, means that all excess battery energy is consumed in the form of heat. Active balancing, as a non-energy-consuming balancing, means that energy is transferred through circuit components to reduce the inconsistency between batteries or battery modules.

[0005] Compared with the typical battery management system that collects current and voltage data, the electrochemical impedance spectroscopy (EIS) technology obtains impedance information in a wide frequency range by measuring the response of the battery terminal voltage to the excitation current. The electrochemical impedance spectrum contains rich information such as the internal material properties of the battery, interface phenomena, and electrochemical reactions. By online detecting the real and imaginary parts of the battery impedance, the battery impedance spectrum can be drawn to track and analyze the battery status. The battery impedance spectrum detection steps include the generation of excitation current, the measurement of excitation current and response voltage, and the calculation of impedance spectrum.

[0006] The accuracy of impedance spectrum detection using specific instruments is higher, but these instruments are expensive and not suitable for large-scale engineering online applications. In the prior art, there are solutions that use passive balancing circuits, power converters or special signal generating circuits to generate the excitation current required for impedance spectrum measurement. For example, a DC / DC converter for charging / discharging the battery and a DC / AC inverter for driving the motor load can be used to generate excitation current, but this often results in large power consumption or impedance spectrum detection can only be performed during the battery charging and discharging process. In the prior art, there are also solutions that reuse passive balancing circuits and impedance spectrum detection functions, but the balancing and impedance spectrum detection functions are both based on the method of causing the battery to discharge to a resistor to consume energy in the form of heat.

[0007] The prior art lacks a solution to use a circuit system for time-sharing multiplexing to realize active battery balancing and impedance spectrum detection functions, and it is difficult to realize active balancing and impedance spectrum detection of each battery in the battery system through low-power energy exchange. Summary of the invention

[0008] In view of the defects and improvement needs of the prior art, the present invention provides a battery active balancing and battery impedance spectrum detection system and method, which aims to solve the problem that the prior art cannot use a low-power mode of energy exchange to achieve battery active balancing and impedance spectrum detection functions using a set of circuit systems in time-sharing multiplexing.

[0009] To achieve the above-mentioned purpose, the present invention provides a battery active balancing and battery impedance spectrum detection system, characterized in that it includes: a control module, a plurality of battery modules and passive devices, wherein the control module is connected to each battery module and the passive device, each battery module is connected in series and then connected in parallel with the passive device, and when the battery active balancing and battery impedance spectrum detection system works in a balancing mode, the control module sends a balancing control signal to a switch array in the passive device to control the path between the battery module and the passive device, thereby realizing active balancing between each battery module; and

[0010] When the battery active balancing and battery impedance spectrum detection system operates in the impedance spectrum detection mode, the control module sends an excitation control signal to the switch array in the passive device, controls the path between the battery module and the passive device, realizes the exchange of electric energy between the battery module and the passive device, generates the excitation current required for impedance spectrum measurement, and realizes the impedance spectrum detection of the battery in the battery module, wherein the switch array includes a first switch array bus and a second switch array bus.

[0011] Further, the battery module includes a control unit, a current acquisition unit, a plurality of impedance spectrum measurement units, a passive unit, and a plurality of batteries connected in series, wherein the control unit controls the switch unit in the passive unit through a first control signal, wherein the current acquisition unit is used to acquire the current flowing through the battery, and the acquired current includes the excitation current at different frequencies required for impedance spectrum measurement; wherein the impedance spectrum measurement unit is used to acquire the terminal voltage of the battery and receive battery current data from the current acquisition unit, wherein the terminal voltage includes the response voltage generated on the battery by the excitation current at different frequencies; the impedance spectrum measurement unit and the control unit calculate the impedance spectrum of the battery according to the response voltage and the excitation current. Wherein, the passive unit includes a switch unit, a first unit resistor, and a first unit capacitor, wherein the first unit resistor and the first unit capacitor are connected in series and connected in parallel with the switch unit, wherein the switch unit includes a first switch unit bus and a second switch unit bus.

[0012] Furthermore, the passive device also includes: a first array resistor, a first array inductor group, a first array varistor and a first array capacitor group, wherein the first array inductor group is connected in parallel with the first array varistor and then in series with the first array resistor and the first array capacitor group, and the first array resistor, the first array capacitor group and the first array inductor group are connected in series and then in parallel with the switch array, wherein the first array inductor group includes a plurality of parallel inductors and switch branches, and the control module controls the change of the inductance value of the first array inductor group through a branch switching control signal, and the first array capacitor group includes a plurality of parallel capacitors and switch branches, and the control module controls the change of the capacitance value of the first array capacitor group through a branch switching control signal.

[0013] Furthermore, the first battery module and the second battery module in the plurality of battery modules implement active balancing in the following manner:

[0014] The first group of array switches is turned on, and the other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, and the negative electrode of the first battery module is connected to one end of the first array capacitor group, so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the first battery module;

[0015] Turning on the second group of array switches, while turning off the other switches in the switch array, connecting the positive electrode of the second battery module to one end of the first array resistor, and connecting the negative electrode of the second battery module to one end of the first array capacitor group, so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the second battery module; and

[0016] The first group of array switches and the second group of array switches are alternately turned on so that the voltage difference between the first battery module and the second battery module is less than a first preset voltage, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the second group of array switches includes: a switch connected between the positive electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the negative electrode of the second battery module and the second switch array bus.

[0017] Furthermore, the manner in which the excitation current is generated by the electric energy exchange between the first battery module and the second battery module in the plurality of battery modules is as follows:

[0018] The first group of array switches is turned on, and other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, the negative electrode of the first battery module is connected to one end of the first array capacitor group, and a damped oscillation occurs between the first battery module and the passive device to generate an excitation current;

[0019] The third group of array switches is turned on, and other switches in the switch array are turned off. The negative electrode of the second battery module is connected to one end of the first array resistor, and the positive electrode of the second battery module is connected to one end of the first array capacitor group. The second battery module and the passive device generate damped oscillation to generate excitation current.

[0020] The first group of array switches and the third group of array switches are alternately turned on, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the third group of array switches includes: a switch connected between the negative electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the positive electrode of the second battery module and the second switch array bus.

[0021] Furthermore, the first battery and the second battery in the battery module are actively balanced in the following manner:

[0022] The first group of unit switches is turned on, and the other switches in the switch unit are turned off, the positive electrode of the first battery is connected to one end of the first unit resistor, and the negative electrode of the first battery is connected to one end of the first unit capacitor, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the first battery;

[0023] Turning on the second group of unit switches, while turning off the other switches in the switch unit, connecting the positive electrode of the second battery to one end of the first unit resistor, and connecting the negative electrode of the second battery to one end of the first unit capacitor, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the second battery; and

[0024] The first group of unit switches and the second group of unit switches are alternately turned on so that the voltage difference between the first battery and the second battery is less than a second preset voltage. The first group of unit switches includes: a switch connected between the positive electrode of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the first battery and the second switch unit bus; the second group of unit switches includes: a switch connected between the positive electrode of the second battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the second battery and the second switch unit bus.

[0025] The present invention also discloses a method for detecting and calculating a battery impedance spectrum by a battery active equalization and battery impedance spectrum detection system, which is characterized by comprising the following steps:

[0026] Step S1: Determine the characteristic frequency points of the impedance spectrum sweep and the number of battery modules, where the number of characteristic frequency points is p, the number of battery modules is n, and x=1;

[0027] Step S2: performing impedance spectrum measurement on the battery module x in the battery module, assuming that j=1;

[0028] Step S3: The control module sends an excitation control signal and a branch switching control signal to control the passive device, and determines and controls the capacitance value of the first array capacitor group, the inductance value of the first array inductor group and the first switch switching frequency according to the requirement of generating the jth characteristic frequency excitation current, performs switch switching control according to the first switch switching frequency, and generates an excitation current on the battery module x;

[0029] Step S4: In the battery module x, the impedance spectrum measurement unit measures the terminal voltage of each battery and obtains the battery current data from the current acquisition unit, calculates the real part and imaginary part of the impedance of the battery at the jth characteristic frequency point, and uploads the impedance data to the control unit in the battery module x;

[0030] Step S5: the control unit receives the impedance of each battery in the battery module x at the jth characteristic frequency point;

[0031] Step S6: if j<p, then j=j+1, and the process returns to step S3; if j≥p, the impedance spectrum detection of all batteries in the battery module x is completed, and step S7 is executed;

[0032] Step S7: the control unit calculates the impedance spectrum of each battery in the battery module x;

[0033] Step S8: If x<n, then x=x+1, and return to step S2; if x≥n, execute step S9;

[0034] Step S9: the control units in all battery modules upload the battery impedance spectrum data to the control module.

[0035] Furthermore, the method for detecting and calculating the battery impedance spectrum by the battery active balancing and battery impedance spectrum detection system also includes generating an excitation current by exchanging electric energy between a first battery module and a second battery module in the plurality of battery modules, specifically in the following manner:

[0036] The first group of array switches is turned on, and other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, the negative electrode of the first battery module is connected to one end of the first array capacitor group, and a damped oscillation occurs between the first battery module and the passive device to generate an excitation current;

[0037] Turning on the third group of array switches, disconnecting other switches in the switch array, connecting the negative electrode of the second battery module to one end of the first array resistor, connecting the positive electrode of the second battery module to one end of the first array capacitor group, and generating an excitation current by damped oscillation between the second battery module and the passive device; and

[0038] The first group of array switches and the third group of array switches are alternately turned on, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the third group of array switches includes: a switch connected between the negative electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the positive electrode of the second battery module and the second switch array bus.

[0039] The present invention also discloses a method for realizing active battery equalization by using a battery active equalization and battery impedance spectrum detection system, which is characterized by comprising the following steps:

[0040] Step S10: setting a second switch switching frequency, a first preset voltage as a threshold for ending balancing between battery modules, and a second preset voltage as a threshold for ending balancing between batteries in the battery module;

[0041] Step S11: selecting a first battery module and a second battery module from the battery modules connected in series;

[0042] Step S12: balancing the first battery module and the second battery module, and the control module controls the switch array to be alternately turned on at a second switch switching frequency;

[0043] Step S13: determining whether the voltage difference between the first battery module and the second battery module is less than a first preset voltage; when the voltage difference between the first battery module and the second battery module is less than the first preset voltage, the equalization between the first battery module and the second battery module is completed, and step S14 is executed; otherwise, the process returns to step S12;

[0044] Step S14: determining whether the voltage difference between the battery modules connected in series is less than a first preset voltage, if yes, executing step S15, otherwise, returning to executing step S11;

[0045] Step S15: selecting a first battery and a second battery in the battery module;

[0046] Step S16: balancing the first battery and the second battery in the battery module, and the control unit controls the switch unit to be alternately turned on at a second switch switching frequency;

[0047] Step S17: determining whether the voltage difference between the first battery and the second battery is less than a second preset voltage; if the voltage difference between the first battery and the second battery is less than the second preset voltage, executing step S18; otherwise, returning to executing step S16;

[0048] Step S18: Determine whether the voltage difference between any two batteries in each battery module is less than the second preset voltage. When the voltage difference between any two batteries in each battery module is less than the second preset voltage, the balancing is completed; otherwise, return to step S15.

[0049] Furthermore, the balancing steps of the first battery module and the second battery module are as follows:

[0050] Turning on the first group of array switches and disconnecting other switches in the switch array so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the first battery module;

[0051] Turning on the second group of array switches and turning off other switches in the switch array, so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the second battery module group; and

[0052] The first group of array switches and the second group of array switches are alternately turned on at the second switch switching frequency, so that the voltage difference between the first battery module and the second battery module is less than a first preset voltage, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the second group of array switches includes: a switch connected between the positive electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the negative electrode of the second battery module and the second switch array bus;

[0053] The steps of balancing the first battery and the second battery in the battery module are as follows:

[0054] Turning on the first group of unit switches and disconnecting other switches in the switch unit so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the first battery;

[0055] Turning on the second group of unit switches and turning off other switches in the switch unit, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the second battery; and

[0056] The first group of unit switches and the second group of unit switches are alternately turned on at the second switch switching frequency, so that the voltage difference between the first battery and the second battery is less than a second preset voltage. The first group of unit switches includes: a switch connected between the positive electrode of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the first battery and the second switch unit bus; the second group of unit switches includes: a switch connected between the positive electrode of the second battery and the first switch unit bus, the second unit switch, and a switch connected between the negative electrode of the second battery and the second switch unit bus.

[0057] Compared with the prior art, the above technical solutions conceived by the present invention can achieve the following

[0058] Beneficial effects:

[0059] The present invention provides a battery active balancing and battery impedance spectrum detection system and method. Compared with the prior art, this solution can use a set of circuit systems in a battery management system to realize the battery active balancing and impedance spectrum detection functions in a time-sharing multiplexing manner, and can realize active balancing between battery modules and active balancing between batteries in a battery module through a convenient and reliable control method, and can generate the excitation current required for impedance spectrum measurement on each battery in the battery system in turn. Secondly, this solution simplifies the impedance spectrum measurement circuit through an impedance spectrum measurement unit, and combines the excitation current generation control method based on a switch array and passive devices, which can realize the impedance spectrum detection calculation of each battery in the battery system while greatly saving the system computing power, and optimize the performance of the battery management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a module schematic diagram of a battery active balancing and battery impedance spectrum detection system provided by an embodiment of the present invention;

[0061] Figure 2 It is a schematic diagram of the structure inside a battery module in a battery active balancing and battery impedance spectrum detection system provided by an embodiment of the present invention;

[0062] Figure 3 It is a flow chart of a method for impedance spectrum detection in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention;

[0063] Figure 4 It is a flow chart of a method for battery balancing in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention;

[0064] Figure 5 It is a waveform diagram of an excitation current generated on a battery in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0066] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0067] Figure 1FIG. 1 is a schematic diagram of a module of a battery active balancing and battery impedance spectrum detection system provided by an embodiment of the present invention. Figure 1 As shown, the battery active balancing and battery impedance spectrum detection system includes battery modules 1, battery modules 2...battery modules n, passive devices and control modules connected in series in sequence. The control module is connected to each battery module and passive device, wherein the passive device is connected in parallel with the battery modules connected in series. Each battery module includes battery 1, battery 2...battery m connected in series in sequence. Each battery is connected to an impedance spectrum measurement unit, wherein m and n are both natural numbers greater than 1. Further, each battery module also includes a control unit, a current acquisition unit and a passive unit. The current acquisition unit is connected in series with each battery and connected to the impedance spectrum measurement unit. The current acquisition unit is used to measure the current flowing through each battery. The impedance spectrum measurement unit is used to measure the terminal voltage of the battery and receive the battery current data from the current acquisition unit. The control unit controls the conduction and closure of the switch in the passive unit through a control signal. Specifically, the control signal here is used to realize active balancing of each battery in the battery module.

[0068] Specifically, the passive device includes a switch array, a first array resistor R, a first array inductor group L, a first array varistor MOV0 and a first array capacitor group C, wherein the first array inductor group L is connected in parallel with the first array varistor MOV0 and then connected in series with the first array resistor R and the first array capacitor group C, and the series-connected R, L, and C series branches are connected in parallel with the switch array, the first array resistor R is connected to the positive electrode of the battery module 1 through switches K1 and K2, and the first array capacitor group C is connected through switch K 2(n+1) The switch array includes a first switch array bus 1 and a second switch array bus 2, and each battery module is connected to the first switch array bus 1 and the second switch array bus 2 through a switch. The first array inductor group L includes a plurality of parallel inductors and switch branches ( Figure 1 The inductance value can be changed under the control of the branch switching control signal issued by the control module. The first array capacitor group C includes a plurality of parallel capacitors and switch branches ( Figure 1 The capacitance value can be changed under the control of the branch switching control signal sent by the control module. When the system is working, the varistor MOV0 can make the voltage across the first array inductor group L always within the safe rated voltage value to ensure the safe operation of the system.

[0069] Furthermore, the positive electrode of battery module 1 is used as the positive electrode of the series battery module, and the negative electrode of battery module n is used as the negative electrode of the series battery module. Let a be a variable of each non-negative integer in the range of 1≤a≤n, representing the ath battery module; the positive electrode of battery module a is connected through switch K 2a-1 Connected to the first switch array bus 1, the negative electrode of battery module a is connected through switch K2a+1 Connected to the first switch array bus 1, the negative electrode of battery module a is connected through switch K 2(a+1) Connected to the second switch array bus 2, except for battery module 1, the positive electrode of battery module a is connected through switch K 2a Connected to the second switch array bus 2, each battery module and each switch are connected in this way. Specifically, the control module controls the switch in the passive device through the control signal, and through the exchange of electric energy, realizes active balancing between the two battery modules, or generates the excitation current required for impedance spectrum detection, and then realizes active balancing of the n series battery modules in turn, or generates excitation current in turn. The control signal here includes a balancing control signal, an excitation control signal and a branch switching control signal. When the impedance spectrum is detected, the frequency of the switch conduction is the first switch switching frequency; when the battery modules and the batteries in the battery module are actively balanced, the frequency of the switch conduction is the second switch switching frequency.

[0070] When the battery active balancing and battery impedance spectrum detection system works in the balancing mode, the active balancing between the first battery module a and the second battery module b is taken as an example to illustrate the balancing process of the system. Let a be a variable that can take values ​​of non-negative integers in the range of 1≤a≤n, let b be a variable that can take values ​​of non-negative integers in the range of 2≤b≤n, where b≠a, in other words, the first battery module a can be any battery module from battery module 1 to battery module n, and the second battery module b can be any battery module from battery module 2 to battery module n except the first battery module a. The control module sends a balancing control signal to the passive device, controls the switch array outside the battery module, and enables the two battery modules to exchange energy with the R, L, and C series branches in the passive device respectively within one switching cycle, thereby realizing energy transfer and active balancing between battery modules.

[0071] Specifically, the first group of array switches K is turned on. 2a-1 , K2, K 2(a+1) , and all other switches in the switch array are in the closed state, so that the positive electrode of the first battery module a is connected to one end of the first array resistor R, and the negative electrode of the first battery module a is connected to one end of the first array capacitor group C. After a period of time, the terminal voltage of the first array capacitor group C is equal to the terminal voltage of the first battery module a; then the second group of array switches K is turned on 2b-1 , K2, K 2(b+1), and all other switches in the switch array are closed. At this time, the positive electrode of the second battery module b is connected to one end of the first array resistor R, and the negative electrode of the second battery module b is connected to one end of the first array capacitor group C. After a period of time, the terminal voltage of the first array capacitor group C is equal to the terminal voltage of the second battery module b. The equality in the present invention is not completely identical in a mathematical sense, and equality includes similar or close values. By alternately turning on the first group of array switches and the second group of array switches, the energy of the battery module with a relatively high terminal voltage can be transferred to the battery module with a relatively low terminal voltage. The speed of energy transfer can be changed by changing the frequency of alternating conduction of the two groups of switches. The frequency of alternating conduction is referred to as the second switch switching frequency fs. Further, when the voltage difference between the first battery module a and the second battery module b is less than the first preset voltage Vs, it indicates that the first battery module a and the second battery module b are balanced. Here, the first preset voltage Vs is the absolute value of the voltage difference between the first battery module a and the second battery module b. The first battery module and the second battery module here are any two battery modules in the series battery module of the present invention. Preferably, the two battery modules with the largest voltage difference are selected to start balancing. The first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus 1, a second array switch K2, and a switch connected between the negative electrode of the first battery module and the second switch array bus 2; the second group of array switches includes: a switch connected between the positive electrode of the second battery module and the first switch array bus 1, a second array switch K2, and a switch connected between the negative electrode of the second battery module and the second switch array bus 2.

[0072] Furthermore, by changing the values ​​of variables a and b and following the above rule, energy transfer between any two battery modules can be achieved, thereby achieving active balancing between all battery modules.

[0073] When the battery active balancing and battery impedance spectrum detection system works in the impedance spectrum detection mode, it is first necessary to realize the current excitation between the battery modules. Specifically, the process of realizing current excitation between the battery modules of the present invention through the exchange of electric energy is explained by taking the mutual generation of excitation current between the first battery module a and the second battery module b as an example, so that the mutual generation of excitation current between the first battery module a and the second battery module b is achieved. In the embodiment of the present invention, in the positive half cycle of a switching cycle, the control module controls the conduction of the first group of array switches K through the excitation control signal 2a-1 , K2, K 2(a+1), all other switches in the switch array are in the off state, the positive electrode of the first battery module a is connected to one end of the first array resistor R, the negative electrode of the first battery module a is connected to one end of the first array capacitor group C, and a damped oscillation occurs between the first battery module a and the R, L, C series branch to generate an excitation current; in the negative half cycle of the same switching cycle, the control module controls the third group of array switches K corresponding to the second battery module b through the excitation control signal 2b+1 , K2, K 2b The negative electrode of the second battery module b is connected to one end of the first array resistor R, and the positive electrode of the second battery module b is connected to one end of the first array capacitor group C. The second battery module b and the R, L, C series branch generate damped oscillation to generate excitation current. In one switching cycle, the first group of array switches K are alternately turned on. 2a-1 , K2, K 2(a+1) And the third set of array switches K 2b+1 , K2, K 2b The first battery module a and the second battery module b are alternately provided with excitation currents. The control module controls the capacitance value of the first array capacitor group C and the inductance value of the first array inductor group L through the branch switching control signal, so as to change the frequency of the damped oscillation, thereby generating excitation currents of different frequencies, and alternately turning on the first array switch K at the first switch switching frequency. 2a-1 , K2, K 2(a+1) And the third set of array switches K 2b+1 , K2, K 2b , until all batteries in the first battery module a and the second battery module b complete the impedance spectrum measurement, the switch alternating conduction operation is ended. The third group of array switches here are: the switch connected between the negative electrode of the second battery module b and the first switch array bus 1, the second array switch K2, and the switch connected between the positive electrode of the second battery module b and the second switch array bus 2. By changing the first switch switching frequency of the alternating conduction of the first group of array switches and the third group of array switches by the control module, the duration of the excitation current generated on the battery module in one switching cycle can be changed, thereby meeting the needs of impedance spectrum detection.

[0074] Furthermore, by changing the values ​​of variables a and b and following the above rule, the power exchange between any two battery modules can be achieved, and then the excitation current required for battery impedance spectrum measurement can be generated on each battery module in turn.

[0075] Figure 2It is a schematic diagram of the structure inside the battery module in a battery active balancing and battery impedance spectrum detection system provided by an embodiment of the present invention. The internal structures of battery module 1...battery module n are the same, and battery module 1 is taken as an example for explanation. As shown in the figure, batteries 1, ..., and batteries m in battery module 1 are connected in series in sequence, where m is a non-negative integer greater than 1. The positive electrode of battery 1 is connected in series with the current collection unit as the positive electrode of battery module 1, and the negative electrode of battery m is used as the negative electrode of battery module 1. The control unit controls the conduction and closure of the switch in switch unit 1 through a first control signal. Let g be a variable that can take values ​​of non-negative integers in the range of 1≤g≤m, g represents the gth battery in battery module 1, and the positive electrode of battery g is connected through switch Q 2g-1 Connected to the first switch unit bus 1, the negative electrode of battery g is connected through switch Q 2g+1 Connected to the first switch unit bus 1, the negative electrode of battery g is connected through switch Q 2(g+1) Connected to the second switch unit bus 2, in addition to battery 1, the positive electrode of battery g is connected through switch Q 2g The passive unit 1 also includes a first unit resistor R1 and a first unit capacitor C1, wherein the first unit resistor R1 and the first unit capacitor C1 are connected in series, the first unit resistor R1 is connected to the positive electrode of the battery 1 through the first unit switch Q1 and the second unit switch Q2, and the first unit capacitor C1 is connected to the positive electrode of the battery 1 through the switch Q1. 2(m+1) Connected to the negative terminal of battery m.

[0076] In one embodiment, the method of achieving active balancing between batteries within a battery module is similar to the method of achieving active balancing between battery modules. Figure 2 As shown, the method of achieving balancing between the first battery g and the second battery h in the battery module 1 is used as an example to illustrate the process of balancing between batteries in the present invention. The methods of achieving balancing between batteries in other battery modules are the same, and will not be described in detail to avoid redundancy. Figure 2 As shown, a first battery g and a second battery h are selected in the battery module 1. Preferably, two batteries with the largest voltage difference are selected to start balancing. The balancing concept of the present invention is not limited. Specifically, the first group of unit switches Q 2g-1 , Q2, Q 2(g+1) , the other switches in the switch unit 1 are disconnected, the positive electrode of the first battery g is connected to one end of the first unit resistor R1, and the negative electrode of the first battery g is connected to one end of the first unit capacitor C1. After a period of time, the terminal voltage of the first unit capacitor C1 is equal to the terminal voltage of the first battery g. The equality here is not completely equal in the mathematical sense, including situations where the values ​​are close or similar; further, the second group of unit switches Q is turned on 2h-1 , Q2, Q 2(h+1), the other switches in the switch unit 1 are disconnected, the positive electrode of the second battery h is connected to one end of the first unit resistor R1, and the negative electrode of the second battery h is connected to one end of the first unit capacitor C1. After a period of time, the terminal voltage of the first unit capacitor C1 is equal to the terminal voltage of the second battery h. The equality here is not completely equal in the mathematical sense, including situations where the values ​​are close or similar. By alternately turning on the first group of unit switches Q 2g-1 , Q2, Q 2(g+1) And the second group of unit switches Q 2h-1 , Q2, Q 2(h+1) , so that the energy of the first battery g with a higher terminal voltage is transferred to the second battery h with a lower terminal voltage, thereby realizing active balancing between the two batteries. The balancing method between other batteries in the battery module is similar. The frequency of alternating conduction here is called the second switch switching frequency fs. Specifically, when the voltage difference between the first battery g and the second battery h is less than the second preset voltage Vr, it means that the first battery g and the second battery h are balanced. Here, the second preset voltage Vr is the absolute value of the voltage difference between the first battery g and the second battery h. The first group of unit switches here are: the switch connected between the positive electrode of the first battery g and the first switch unit bus 1, the second unit switch Q2, and the switch connected between the negative electrode of the first battery g and the second switch unit bus 2. The second group of unit switches have the same connection rules.

[0077] In one embodiment, in order to better obtain the impedance spectrum information of the battery, in the online detection of the battery status, the battery detection requirements are safety warning, charge state estimation, health state estimation, etc. In combination with the actual engineering situation and requirements, the selected impedance characteristic frequency point to be measured is determined according to the required battery status detection amount. Specifically, the selected characteristic frequency point can only be the damped oscillation frequency that can be generated by changing the inductance value of the first array inductor group L and the capacitance value of the first array capacitor group C. In the application, the first array inductor group L and the first array capacitor group C can be reasonably designed in advance to make the impedance characteristic frequency points that can be taken as rich as possible and the impedance spectrum characteristic frequency points that are most valuable for battery status detection. For example, the estimation of the temperature inside the battery is an effective method for battery operation safety warning. Then, for the estimation of the temperature inside the battery, a logarithmic scale equidistant interval point selection method can be used in the 1000hz-1hz frequency range that is more sensitive to the temperature change inside the battery to select multiple characteristic frequency points for impedance detection, such as selecting p characteristic frequency points that need to be measured for impedance, and p is 9. Taking the detection of the impedance spectrum of each battery in the battery module 1 as an example, after the excitation current of the jth characteristic frequency (the variable j takes the value of each natural number in the range of 1≤j≤p) is generated on the battery module 1, the control module sends an impedance spectrum detection instruction to the control unit in the battery module 1 ( Figure 1(not shown), the control unit sends control instructions to the current acquisition unit and each impedance spectrum measurement unit. The current flowing through each battery in the battery module 1 is measured by the current acquisition unit. The current acquisition unit collects the current flowing through each battery in real time and sends the current data to the corresponding impedance spectrum measurement unit. The current data includes the excitation current data for impedance spectrum measurement. Both ends of each battery are respectively connected to the voltage measurement port of the corresponding impedance spectrum measurement unit. The impedance spectrum measurement unit measures the terminal voltage of the corresponding battery in real time. The terminal voltage data includes the response voltage data generated by the excitation current on the battery. The impedance spectrum measurement unit calculates the real and imaginary impedance of the corresponding battery at the jth characteristic frequency point based on the voltage measurement data and the current measurement data.

[0078] In an embodiment of the present invention, each impedance spectrum measurement unit in the battery module forms a ring topology communication with the control unit through a daisy chain communication mode, and each impedance spectrum measurement unit receives the control instruction of the control unit and transmits the calculated impedance real and imaginary values ​​of each battery at the jth characteristic frequency point to the control unit. Specifically, according to the impedance spectrum detection requirements, the value of the variable j is changed, that is, the characteristic frequency point is changed. According to the aforementioned control method, the control module generates excitation currents of different frequencies on the battery module 1 by controlling the passive devices, and the impedance real and imaginary values ​​of each battery at different characteristic frequency points are measured and calculated through the impedance spectrum measurement unit and the control unit structure and working mode and transmitted to the control unit.

[0079] According to the impedance spectrum detection requirements and the aforementioned control method, the control module generates excitation currents of different frequencies on each battery module in turn by controlling passive devices. The impedance spectrum measurement unit measures and calculates the real and imaginary impedance values ​​of each battery in each battery module at different characteristic frequencies and transmits them to the corresponding control unit.

[0080] Therefore, after the control unit in each battery module receives the real and imaginary impedance data results of each battery in the battery module at multiple frequencies, the control unit calculates and organizes the impedance spectrum data of each battery in the corresponding battery module and transmits it to the control module, and the control module obtains the impedance spectrum information of each battery in each battery module.

[0081] Specifically, the control unit in the battery module controls the switch unit by sending a first control signal to the passive unit to achieve active balancing between the batteries in the battery module; the control module sends a balancing control signal to the passive device to achieve active balancing between the battery modules, or sends an excitation control signal and a branch switching control signal to generate excitation currents of different frequencies on each battery module in turn, and perform impedance spectrum detection.

[0082] In a preferred embodiment, the impedance spectrum measurement unit may be composed of a single-cell management chip with integrated impedance measurement function available on the market and its peripheral circuits.

[0083] Figure 3 is a flow chart of a method for impedance spectrum detection in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention, Figure 3 Will combine Figure 1 and Figure 2 To explain, the impedance spectrum detection steps are as follows:

[0084] S1: Determine the characteristic frequency points of the impedance spectrum sweep and the number of battery modules, the number of characteristic frequency points p, the number of battery modules n, where the number of battery modules n is the actual number of battery modules, set the variable x, let x=1.

[0085] S2: Perform impedance spectrum detection on battery module x, set variable j, and set j = 1. Specifically, starting from battery module 1 in the series battery modules, perform impedance spectrum detection on each battery module, where variable j represents the jth characteristic frequency point, and x represents the xth battery module.

[0086] S3: The control module sends an excitation control signal and a branch switching control signal to control the passive components. According to the requirement of generating the j-th characteristic frequency excitation current, the capacitance value of the first array capacitor group, the inductance value of the first array inductor group and the first switch switching frequency are determined and controlled. The switch switching control is performed according to the first switch switching frequency to generate an excitation current on the battery module x. The switching control method refers to the on and off mode of the switch when the excitation current is generated on the above-mentioned battery module a.

[0087] S4: In the battery module x, the impedance spectrum measurement unit measures the terminal voltage of each battery and obtains the battery current data from the current acquisition unit, calculates the real and imaginary impedance parts of the battery at the jth characteristic frequency point, and uploads the impedance data to the control unit in the battery module x.

[0088] S5: The control unit receives the impedance of each battery in the battery module x at the jth characteristic frequency point;

[0089] S6: If j<p, then j=j+1, and return to S3; if j≥p, the impedance spectrum detection of all batteries in the battery module x is completed, and execute S7.

[0090] S7: The control unit calculates the impedance spectrum of each battery in the battery module x.

[0091] S8: If x<n, then x=x+1, and return to S2; if x≥n, the impedance spectrum detection of all batteries in battery module 1 ... battery module n is completed, and S9 is executed.

[0092] S9: The control units in all battery modules upload the battery impedance spectrum data to the control module to complete the battery impedance spectrum detection. The entire detection process can be carried out without affecting the normal charging and discharging operation of the battery system, realizing in-situ online detection.

[0093] Figure 4 This is a flow chart of a method for battery balancing in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention. The steps of balancing between battery modules and between batteries in a battery module are as follows:

[0094] S10: Set the second switch switching frequency fs, the first preset voltage Vs as the threshold for balancing between battery modules, and the second preset voltage Vr as the threshold for balancing between batteries in the battery module. Specifically, when the voltage difference between any two battery modules is less than the first preset voltage Vs, the balancing between the battery modules is terminated, and when the voltage difference between any two batteries in each battery module is less than the second preset voltage Vr, the battery balancing in the battery module is terminated.

[0095] S11: Select the first battery module a and the second battery module b from the battery modules connected in series. In one embodiment of the present invention, two battery modules with the largest voltage difference are selected for balancing. The selection method is not unique, and the battery modules with the largest voltage difference are preferably balanced.

[0096] S12: The control module controls the switch array to alternately conduct at the second switch switching frequency fs to achieve balancing. For a specific method of balancing between two battery modules, refer to the above Figure 1 The balancing process between the first battery module a and the second battery module b.

[0097] S13: Determine whether the voltage difference between the first battery module a and the second battery module b is less than the first preset voltage Vs. When the voltage difference between the first battery module a and the second battery module b is less than the first preset voltage Vs, the first battery module a and the second battery module b are balanced and S14 is executed. Otherwise, return to execute S12.

[0098] S14: Determine whether the voltage differences between the battery modules connected in series are all less than the first preset voltage Vs. Specifically, determine whether the voltage differences between any two battery modules are all less than the first preset voltage Vs. If yes, execute S15, otherwise, return to execute S11.

[0099] S15: Select a first battery g and a second battery h in the battery module. Preferably, two batteries with the largest voltage difference in the battery module are selected for balancing.

[0100] S16: The control unit controls the switch unit to be alternately turned on at the second switch switching frequency fs to achieve a balancing effect. Specifically, the balancing process between the first battery g and the second battery h is as described above. Figure 2 Description in .

[0101] S17: Determine whether the voltage difference between the first battery g and the second battery h is less than the second preset voltage Vr. When the voltage difference between the first battery g and the second battery h is less than the second preset voltage Vr, the balancing between the first battery g and the second battery h is completed, and S18 is executed. Otherwise, return to execute S16.

[0102] S18: Determine whether the voltage difference between any two batteries in each battery module is less than the second preset voltage Vr. When the voltage difference between any two batteries in each battery module is less than the second preset voltage Vr, it means that the batteries in the battery module are balanced. Otherwise, return to execute S15 and continue the balancing operation until each battery in each battery module reaches the judgment standard of balanced completion.

[0103] Those skilled in the art should understand that the first preset voltage Vs of the voltage difference between the battery modules and the second preset voltage Vr of the voltage difference between the batteries can be set based on experience or usage scenarios and are not unique values.

[0104] Figure 5 This is a waveform diagram of the excitation current generated on the battery in a battery active balancing and battery impedance spectrum detection system and method provided by an embodiment of the present invention. As shown in the figure, by controlling the passive components, the current waveform of the battery module can quickly enter a stable state, providing excitation current conditions for impedance spectrum measurement. The value and change of the specific frequency can be determined and adjusted according to the impedance spectrum detection requirements.

[0105] Through the battery active balancing and battery impedance spectrum detection system and method disclosed in the present invention, a set of circuit systems can be used in a battery management system to realize active balancing and impedance spectrum detection functions by time-sharing multiplexing; based on the control of passive devices, each battery module periodically exchanges electric energy with the passive devices, so that current excitation between each battery module can be realized, and excitation currents at different frequencies required for measuring impedance spectrum are generated on each battery in turn; based on the current acquisition unit, the impedance spectrum measurement unit and the control unit, the impedance spectrum detection calculation of each battery in the battery system can be realized while greatly saving the system computing power; based on the control of passive devices and the switch unit in the battery module, active balancing between each battery module and between each battery in the battery module can also be realized.

[0106] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery active balancing and battery impedance spectrum detection system, characterized in that: include: A control module, a plurality of battery modules and passive devices, wherein the control module is connected to each battery module and the passive device, and each battery module is connected in series and then in parallel with the passive device. When the battery active balancing and battery impedance spectrum detection system works in the balancing mode, the control module sends a balancing control signal to the switch array in the passive device to control the path between the battery module and the passive device to achieve active balancing between the battery modules; as well as When the battery active balancing and battery impedance spectrum detection system operates in the impedance spectrum detection mode, the control module sends an excitation control signal to the switch array in the passive device, controls the path between the battery module and the passive device, realizes the exchange of electric energy between the battery module and the passive device, generates the excitation current required for impedance spectrum measurement, and realizes the impedance spectrum detection of the battery in the battery module, wherein the switch array includes a first switch array bus and a second switch array bus.

2. The battery active balancing and battery impedance spectrum detection system according to claim 1, characterized in that: The battery module includes a control unit, a current acquisition unit, a plurality of impedance spectrum measurement units, a passive unit, and a plurality of batteries connected in series, wherein the control unit controls the switch unit in the passive unit through a first control signal, wherein the current acquisition unit is used to acquire the current flowing through the battery, and the acquired current includes the excitation current at different frequencies required for impedance spectrum measurement; wherein the impedance spectrum measurement unit is used to acquire the terminal voltage of the battery and receive the battery current data from the current acquisition unit, wherein the terminal voltage includes the response voltage generated on the battery by the excitation current at different frequencies; the impedance spectrum measurement unit and the control unit calculate the impedance spectrum of the battery according to the response voltage and the excitation current. Wherein, the passive unit includes a switch unit, a first unit resistor, and a first unit capacitor, wherein the first unit resistor and the first unit capacitor are connected in series and connected in parallel with the switch unit, wherein the switch unit includes a first switch unit bus and a second switch unit bus.

3. The battery active balancing and battery impedance spectrum detection system according to claim 1, characterized in that: The passive device also includes: a first array resistor, a first array inductor group, a first array varistor and a first array capacitor group, wherein the first array inductor group is connected in parallel with the first array varistor and then in series with the first array resistor and the first array capacitor group, and the first array resistor, the first array capacitor group and the first array inductor group are connected in series and then in parallel with the switch array, wherein the first array inductor group includes a plurality of parallel inductors and switch branches, and the control module controls the change of the inductance value of the first array inductor group through a branch switching control signal, and the first array capacitor group includes a plurality of parallel capacitors and switch branches, and the control module controls the change of the capacitance value of the first array capacitor group through a branch switching control signal.

4. The battery active balancing and battery impedance spectrum detection system according to claim 1, characterized in that: The first battery module and the second battery module in the plurality of battery modules implement active balancing in the following manner: The first group of array switches is turned on, and the other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, and the negative electrode of the first battery module is connected to one end of the first array capacitor group, so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the first battery module; The second group of array switches is turned on, and the other switches in the switch array are turned off, the positive electrode of the second battery module is connected to one end of the first array resistor, and the negative electrode of the second battery module is connected to one end of the first array capacitor group, so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the second battery module; as well as The first group of array switches and the second group of array switches are alternately turned on so that the voltage difference between the first battery module and the second battery module is less than a first preset voltage, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the second group of array switches includes: a switch connected between the positive electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the negative electrode of the second battery module and the second switch array bus.

5. The battery active balancing and battery impedance spectrum detection system according to claim 1, characterized in that: The manner in which the first battery module and the second battery module in the plurality of battery modules generate an excitation current through electric energy exchange is as follows: The first group of array switches is turned on, and other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, the negative electrode of the first battery module is connected to one end of the first array capacitor group, and a damped oscillation occurs between the first battery module and the passive device to generate an excitation current; The third group of array switches is turned on, and other switches in the switch array are turned off, the negative electrode of the second battery module is connected to one end of the first array resistor, the positive electrode of the second battery module is connected to one end of the first array capacitor group, and the second battery module and the passive device generate damped oscillation to generate excitation current; as well as The first group of array switches and the third group of array switches are alternately turned on, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the third group of array switches includes: a switch connected between the negative electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the positive electrode of the second battery module and the second switch array bus.

6. The battery active balancing and battery impedance spectrum detection system according to claim 2, characterized in that: The method for achieving active balancing of the first battery and the second battery in the battery module is as follows: The first group of unit switches is turned on, and the other switches in the switch unit are turned off, the positive electrode of the first battery is connected to one end of the first unit resistor, and the negative electrode of the first battery is connected to one end of the first unit capacitor, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the first battery; The second group of unit switches is turned on, and the other switches in the switch unit are turned off, the positive electrode of the second battery is connected to one end of the first unit resistor, and the negative electrode of the second battery is connected to one end of the first unit capacitor, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the second battery; as well as The first group of unit switches and the second group of unit switches are alternately turned on so that the voltage difference between the first battery and the second battery is less than a second preset voltage. The first group of unit switches includes: a switch connected between the positive electrode of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the first battery and the second switch unit bus; the second group of unit switches includes: a switch connected between the positive electrode of the second battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the second battery and the second switch unit bus.

7. A method for detecting and calculating a battery impedance spectrum by a battery active balancing and battery impedance spectrum detection system, characterized in that: The following steps are involved: Step S1: Determine the characteristic frequency points of the impedance spectrum sweep and the number of battery modules, where the number of characteristic frequency points is p, the number of battery modules is n, and x=1; Step S2: performing impedance spectrum detection on the battery module x in the battery module, assuming that j=1; Step S3: The control module sends an excitation control signal and a branch switching control signal to control the passive device, and determines and controls the capacitance value of the first array capacitor group, the inductance value of the first array inductor group and the first switch switching frequency according to the requirement of generating the jth characteristic frequency excitation current, performs switch switching control according to the first switch switching frequency, and generates an excitation current on the battery module x; Step S4: In the battery module x, the impedance spectrum measurement unit measures the terminal voltage of each battery and obtains the battery current data from the current acquisition unit, calculates the real part and imaginary part of the impedance of the battery at the jth characteristic frequency point, and uploads the impedance data to the control unit in the battery module x; Step S5: the control unit receives the impedance of each battery in the battery module x at the jth characteristic frequency point; Step S6: if j<p, then j=j+1, and the process returns to step S3; if j≥p, the impedance spectrum detection of all batteries in the battery module x is completed, and step S7 is executed; Step S7: the control unit calculates the impedance spectrum of each battery in the battery module x; Step S8: If x<n, then x=x+1, and return to step S2; if x≥n, execute step S9; Step S9: the control units in all battery modules upload the battery impedance spectrum data to the control module.

8. The method for detecting and calculating the battery impedance spectrum by the battery active equalization and battery impedance spectrum detection system according to claim 7, characterized in that: The method further includes generating an excitation current by exchanging electric energy between a first battery module and a second battery module in the plurality of battery modules, and the specific method is as follows: The first group of array switches is turned on, and other switches in the switch array are turned off, the positive electrode of the first battery module is connected to one end of the first array resistor, the negative electrode of the first battery module is connected to one end of the first array capacitor group, and a damped oscillation occurs between the first battery module and the passive device to generate an excitation current; The third group of array switches is turned on, and other switches in the switch array are turned off, the negative electrode of the second battery module is connected to one end of the first array resistor, the positive electrode of the second battery module is connected to one end of the first array capacitor group, and the second battery module and the passive device generate damped oscillation to generate excitation current; as well as The first group of array switches and the third group of array switches are alternately turned on, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the third group of array switches includes: a switch connected between the negative electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the positive electrode of the second battery module and the second switch array bus.

9. A method for realizing active battery balancing by using a battery active balancing and battery impedance spectrum detection system, characterized in that: The following steps are involved: Step S10: setting a second switch switching frequency, a first preset voltage as a threshold for ending balancing between battery modules, and a second preset voltage as a threshold for ending balancing between batteries in the battery module; Step S11: selecting a first battery module and a second battery module from the battery modules connected in series; Step S12: balancing the first battery module and the second battery module, and the control module controls the switch array to be alternately turned on at a second switch switching frequency; Step S13: determining whether the voltage difference between the first battery module and the second battery module is less than a first preset voltage; when the voltage difference between the first battery module and the second battery module is less than the first preset voltage, the equalization between the first battery module and the second battery module is completed, and step S14 is executed; otherwise, the process returns to step S12; Step S14: determining whether the voltage difference between the battery modules connected in series is less than a first preset voltage, if yes, executing step S15, otherwise, returning to executing step S11; Step S15: selecting a first battery and a second battery in the battery module; Step S16: balancing the first battery and the second battery in the battery module, and the control unit controls the switch unit to be alternately turned on at a second switch switching frequency; Step S17: determining whether the voltage difference between the first battery and the second battery is less than a second preset voltage; if the voltage difference between the first battery and the second battery is less than the second preset voltage, executing step S18; otherwise, returning to executing step S16; Step S18: determining whether the voltage difference between any two batteries in each battery module is less than a second preset voltage, and when the voltage difference between any two batteries in each battery module is less than the second preset voltage, the balancing is completed; Otherwise, the process returns to step S15.

10. The method for realizing active battery balancing by using the battery active balancing and battery impedance spectrum detection system according to claim 9, characterized in that: The steps of balancing the first battery module and the second battery module are as follows: Turning on the first group of array switches and disconnecting other switches in the switch array so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the first battery module; Turning on the second group of array switches and disconnecting other switches in the switch array so that the terminal voltage of the first array capacitor group is equal to the terminal voltage of the second battery module; The first group of array switches and the second group of array switches are alternately turned on at the second switch switching frequency, so that the voltage difference between the first battery module and the second battery module is less than a first preset voltage, wherein the first group of array switches includes: a switch connected between the positive electrode of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and the second switch array bus; the second group of array switches includes: a switch connected between the positive electrode of the second battery module and the first switch array bus, the second array switch, and a switch connected between the negative electrode of the second battery module and the second switch array bus; The steps of balancing the first battery and the second battery in the battery module are as follows: Turning on the first group of unit switches and disconnecting other switches in the switch unit so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the first battery; Turning on the second group of unit switches and turning off other switches in the switch unit, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the second battery; and The first group of unit switches and the second group of unit switches are alternately turned on at the second switch switching frequency, so that the voltage difference between the first battery and the second battery is less than a second preset voltage, wherein the first group of unit switches includes: a switch connected between the positive electrode of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative electrode of the first battery and the second switch unit bus; the second group of unit switches includes: a switch connected between the positive electrode of the second battery and the first switch unit bus, the second unit switch, and a switch connected between the negative electrode of the second battery and the second switch unit bus.

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