A battery active balancing and battery impedance spectroscopy detection system and method

Abstract

The application discloses a battery active balancing and battery impedance spectrum detection system and method, which comprises a control module, a plurality of battery modules and a passive device, wherein the control module is connected with each battery module and the passive device, each battery module is connected in series and then connected in parallel with the passive device, when the system works in a balancing mode, active balancing between each battery module and between each battery in the battery module can be realized; when the system works in an impedance spectrum detection mode, through controlling the exchange of electric energy between the battery module and the passive device, the excitation current required for impedance spectrum measurement is generated on the battery module, and then the impedance spectrum measurement and calculation are realized through a current collection unit, an impedance spectrum measurement unit and a control unit in the battery module. Through the battery active balancing and battery impedance spectrum detection system and method, time-sharing multiplexing can be realized to realize battery active balancing and battery impedance spectrum detection, and the performance of a battery management system is optimized.

Description

Technical Field

[0001] This invention belongs to the field of battery equalization and battery impedance spectrum detection, and more specifically, relates to a battery active equalization and battery impedance spectrum detection system and method. Background Technology

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

[0003] Differences in battery manufacturing and operating environments lead to inconsistencies between individual cells within a battery system. Typically, hundreds or thousands of cells are connected in series and parallel to construct a battery system to meet the voltage and capacity requirements of the load. However, these inconsistencies can cause voltage and capacity imbalances during charging and discharging. Charging or discharging cells outside their permissible voltage range can damage them and even cause safety incidents. Therefore, battery management systems (BMS) need to have battery balancing capabilities to compensate for voltage and capacity imbalances between cells, ensuring the full utilization of the battery system's energy.

[0004] Basic balancing topologies can be broadly categorized into two types: passive balancing and active balancing. Passive balancing, also known as energy-consuming balancing, refers to dissipating excess battery energy as heat. Active balancing, a non-energy-consuming type of balancing, involves transferring energy through circuit components to reduce inconsistencies between batteries or battery modules.

[0005] Compared to typical battery management systems that collect current and voltage data, electrochemical impedance spectroscopy (EIS) technology obtains impedance information over a wide frequency range by measuring the battery's terminal voltage response to an excitation current. EIS contains rich information about the battery's internal material properties, interfacial phenomena, and electrochemical reactions. By detecting the real and imaginary parts of the battery impedance online, an impedance spectrum can be plotted, allowing for the tracking and analysis of the battery's state. The battery impedance spectroscopy detection process includes generating the excitation current, measuring the excitation current and response voltage, and calculating the impedance spectrum.

[0006] While impedance spectrum analysis using specialized instruments offers high accuracy, these instruments are expensive and unsuitable for large-scale online engineering applications. Existing technologies employ passive equalization circuits, power converters, or specialized signal generation circuits to generate the excitation current required for impedance spectrum measurement. For example, DC / DC converters used for charging / discharging batteries, and DC / AC inverters used for driving motor loads, can generate the excitation current, but this often results in significant power consumption or allows impedance spectrum analysis only during battery charging and discharging. Existing technologies also combine passive equalization circuits with impedance spectrum detection, but both equalization and impedance spectrum detection functions rely on discharging the battery into a resistor to dissipate energy as heat.

[0007] Existing technologies lack a solution for using a single circuit system to achieve active battery balancing and impedance spectrum detection. It is difficult to achieve active balancing and impedance spectrum detection for each battery in the battery system through low-power energy exchange. Summary of the Invention

[0008] To address the shortcomings and improvement needs of existing technologies, this invention provides a battery active balancing and battery impedance spectrum detection system and method. Its purpose is to solve the problem that existing technologies cannot achieve battery active balancing and impedance spectrum detection functions through a low-power energy exchange method using a single circuit system in a time-division multiplexing manner.

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

[0010] When the battery active balancing and battery impedance spectrum detection system is operating in impedance spectrum detection mode, the control module sends an excitation control signal to the switch array in the passive device to control the path between the battery module and the passive device, realize the power exchange between the battery module and the passive device, generate the excitation current required for impedance spectrum measurement, and realize the impedance spectrum detection of the battery in the battery module. The switch array includes a first switch array bus and a second switch array bus.

[0011] Furthermore, the battery module includes a control unit, a current acquisition unit, multiple impedance spectrum measurement units, a passive unit, and multiple serially connected batteries. The control unit controls the switching unit in the passive unit via a first control signal. The current acquisition unit acquires the current flowing through the battery, and the acquired current includes excitation currents at different frequencies required for impedance spectrum measurement. The impedance spectrum measurement unit acquires the battery's terminal voltage and receives battery current data from the current acquisition unit. 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 based on the response voltage and the excitation current. The passive unit includes a switching unit, a first unit resistor, and a first unit capacitor. The first unit resistor and the first unit capacitor are connected in series and then in parallel with the switching unit. The switching unit includes a first switching unit bus and a second switching 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. 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. 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. The first array inductor group contains multiple parallel inductor and switch branches. The control module controls the change of the inductance value of the first array inductor group through a branch switching control signal. The first array capacitor group contains multiple parallel capacitor and switch branches. 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 active balancing method for the first and second battery modules among the plurality of battery modules is as follows:

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

[0016] The first set of array switches and the second set 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. The first set of array switches includes: a switch connected between the positive terminal of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative terminal of the first battery module and the second switch array bus. The second set of array switches includes: a switch connected between the positive terminal of the second battery module and the first switch array bus, a second array switch, and a switch connected between the negative terminal of the second battery module and the second switch array bus.

[0017] Furthermore, the method by which the first battery module and the second battery module in the plurality of battery modules generate excitation current through energy exchange is as follows:

[0018] The first set of array switches is turned on, and the other switches in the switch array are turned off. The positive terminal of the first battery module is connected to one end of the first array resistor, and the negative terminal of the first battery module is connected to one end of the first array capacitor group. Damped oscillations occur between the first battery module and the passive device to generate excitation current.

[0019] The third set of array switches is turned on, while the other switches in the switch array are turned off. The negative terminal of the second battery module is connected to one end of the first array resistor, and the positive terminal 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 an excitation current through damped oscillation.

[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 terminal of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative terminal of the first battery module and the second switch array bus; the third group of array switches includes: a switch connected between the negative terminal of the second battery module and the first switch array bus, a second array switch, and a switch connected between the positive terminal of the second battery module and the second switch array bus.

[0021] Furthermore, the active balancing method for the first and second batteries within the battery module is as follows:

[0022] The first set of unit switches is turned on, the other switches in the switch unit are turned off, the positive terminal of the first battery is connected to one end of the first unit resistor, and the negative terminal 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] The second set of unit switches is turned on, the other switches in the switching unit are turned off, the positive terminal of the second battery is connected to one end of the first unit resistor, and the negative terminal 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; and

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

[0025] This invention also discloses a method for detecting and calculating the battery impedance spectrum using a battery active equalization and battery impedance spectrum detection system, 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 let x = 1;

[0027] Step S2: Perform impedance spectrum measurement on battery module x in the battery module, and let j = 1;

[0028] Step S3: The control module sends excitation control signal and 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 switching frequency according to the requirement of generating the excitation current of the j-th characteristic frequency. The switching control is performed according to the first switching frequency to generate the excitation current on the battery module x.

[0029] Step S4: Within the battery module x, the impedance spectrum measurement unit measures the terminal voltage of each battery and obtains battery current data from the current acquisition unit, calculates the real and imaginary parts of the battery impedance at the j-th characteristic frequency point, and uploads the impedance data to the control unit within the battery module x.

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

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

[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, return to step S2; if x ≥ n, execute step S9.

[0034] Step S9: The control unit in all battery modules uploads the battery impedance spectrum data to the control module.

[0035] Furthermore, the method for detecting and calculating the battery impedance spectrum using the battery active balancing and battery impedance spectrum detection system also includes generating an excitation current between the first and second battery modules in multiple battery modules through energy exchange, as detailed below:

[0036] Turn on the first set of array switches and turn off the other switches in the switch array. Connect the positive terminal of the first battery module to one end of the first array resistor and connect the negative terminal of the first battery module to one end of the first array capacitor group. Damped oscillation occurs between the first battery module and the passive device to generate excitation current.

[0037] The third set of array switches is turned on, and the other switches in the switch array are turned off. The negative terminal of the second battery module is connected to one end of the first array resistor, and the positive terminal 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 an excitation current through damped oscillation.

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

[0039] This invention also discloses a method for achieving active battery balancing using a battery active balancing and battery impedance spectrum detection system, characterized by comprising the following steps:

[0040] Step S10: Set the second switch switching frequency, the first preset voltage for the equalization termination threshold between battery modules, and the second preset voltage for the equalization termination threshold between batteries in the battery module.

[0041] Step S11: Select the first battery module and the second battery module from the series-connected battery modules;

[0042] Step S12: Equalize the first battery module and the second battery module, and control the switch array to alternately conduct at the second switch switching frequency.

[0043] Step S13: Determine whether the voltage difference between the first battery module and the second battery module is less than the 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 balancing between the first battery module and the second battery module is completed, and step S14 is executed; otherwise, return to step S12.

[0044] Step S14: Determine whether the voltage difference between the series-connected battery modules is less than the first preset voltage. If yes, proceed to step S15; otherwise, return to step S11.

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

[0046] Step S16: Equalize the first battery and the second battery in the battery module, and control the switching unit to alternately conduct at the second switching frequency;

[0047] Step S17: Determine whether the voltage difference between the first battery and the second battery is less than the second preset voltage. If the voltage difference between the first battery and the second battery is less than the second preset voltage, execute step S18; otherwise, return to execute 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 between the first battery module and the second battery module are as follows:

[0050] Turn on the first set of array switches and turn off the 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] Turn on the second set of array switches, and turn off the 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; and

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

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

[0054] Turn on the first set of unit switches and turn off the other switches in the switching unit, so that the terminal voltage of the first unit capacitor is equal to the terminal voltage of the first battery;

[0055] The second set of unit switches is turned on, and the other switches in the switching unit are turned off, 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 switched on and off at the second 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 terminal of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative terminal of the first battery and the second switch unit bus; the second group of unit switches includes: a switch connected between the positive terminal of the second battery and the first switch unit bus, a second unit switch, and a switch connected between the negative terminal of the second battery and the second switch unit bus.

[0057] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following results.

[0058] Beneficial effects:

[0059] This invention provides a battery active balancing and battery impedance spectrum detection system and method. Compared with existing technologies, this solution can use a single circuit system in a time-division multiplexing configuration within a battery management system to achieve active battery balancing and impedance spectrum detection functions. It can achieve active balancing between battery modules and between individual cells within a battery module through a convenient and reliable control method. It can sequentially generate the excitation current required for impedance spectrum measurement on each cell within the battery system. Furthermore, this solution simplifies the impedance spectrum measurement circuit through an impedance spectrum measurement unit. Combined with an excitation current generation control method based on switch arrays and passive devices, it can achieve impedance spectrum detection and calculation for each cell within the battery system while significantly reducing system computing power, thus optimizing the performance of the battery management system. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of a battery active balancing and battery impedance spectrum detection system provided in one embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram of the internal structure of a battery module in a battery active balancing and battery impedance spectrum detection system according to an embodiment of the present invention;

[0062] Figure 3 This is a flowchart of the impedance spectrum detection method in a battery active equalization and battery impedance spectrum detection system and method provided in one embodiment of the present invention;

[0063] Figure 4 This is a flowchart of a battery equalization method in a battery active equalization and battery impedance spectrum detection system and method provided in an embodiment of the present invention;

[0064] 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 in an embodiment of the present invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

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

[0067] Figure 1This is a schematic diagram of a battery active balancing and battery impedance spectrum detection system provided in one embodiment of the present invention. Figure 1 As shown, the battery active balancing and battery impedance spectrum detection system includes battery modules 1, 2, ..., n connected in series, passive devices, and a control module. The control module is connected to each battery module and passive device, with the passive devices connected in parallel with the series-connected battery modules. Each battery module includes batteries 1, 2, ..., m connected in series, and each battery is connected to an impedance spectrum measurement unit, where m and n are 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 to the impedance spectrum measurement unit. The current acquisition unit measures the current flowing through each battery, and the impedance spectrum measurement unit measures the battery's terminal voltage and receives battery current data from the current acquisition unit. The control unit controls the switching on and off of switches in the passive unit via control signals. Specifically, the control signals here are used to achieve active balancing of the batteries within 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. The first array inductor group L and the first array varistor MOV0 are connected in parallel, and then connected in series with the first array resistor R and the first array capacitor group C. The series branch of R, L, and C is connected in parallel with the switch array. The first array resistor R is connected to the positive terminal of battery module 1 through switches K1 and K2. The first array capacitor group C is connected to the positive terminal of battery module 1 through switch K1. 2(n+1) It is connected to the negative terminal of battery module n. The switch array includes a first switch array bus 1 and a second switch array bus 2. Each battery module is connected to the first switch array bus 1 and the second switch array bus 2 via a switch. The first array inductor group L contains multiple parallel inductor and switch branches ( Figure 1 (Not shown in the image), 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 contains multiple parallel capacitors and switching branches ( Figure 1 (Not shown in the diagram) The capacitance value can be changed under the control of the branch switching control signal issued by the control module. During system operation, the varistor MOV0 can keep the voltage across the first array inductor group L within the safe rated voltage value, ensuring safe system operation.

[0069] Furthermore, the positive terminal of battery module 1 serves as the positive terminal of the series-connected battery module, and the negative terminal of battery module n serves as the negative terminal of the series-connected battery module. Let a be a variable representing each non-negative integer in the range 1 ≤ a ≤ n, indicating the a-th battery module; the positive terminal of battery module a is connected to switch K. 2a-1 Connected to the first switch array bus 1, the negative terminal of battery module a is connected to switch K.2a+1 Connected to the first switch array bus 1, the negative terminal of battery module a is connected to switch K. 2(a+1) Connected to the second switch array bus 2, except for battery module 1, the positive terminal of battery module a is connected to switch K. 2a Connected to the second switch array bus 2, each battery module is connected to each switch in this manner. Specifically, the control module controls the switches in the passive devices through control signals. Through power exchange, it enables active balancing between two battery modules, or generates the excitation current required for impedance spectrum detection. This process is repeated for n series-connected battery modules to achieve active balancing or generate excitation current sequentially. The control signals include balancing control signals, excitation control signals, and branch switching control signals. During impedance spectrum detection, the switch conduction frequency is the first switch switching frequency; during active balancing between battery modules and between batteries within a battery module, the switch conduction frequency is the second switch switching frequency.

[0070] When the battery active balancing and battery impedance spectrum detection system operates in balancing mode, the balancing process of this system is illustrated using the active balancing between the first battery module a and the second battery module b as an example. Let a be a variable that can take any non-negative integer value in the range 1 ≤ a ≤ n, and let b be a variable that can take any non-negative integer value in the range 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 other than the first battery module a. The control module sends a balancing control signal to the passive device, controlling the switch array outside the battery module, so that the two battery modules exchange energy with the R, L, C series branches in the passive device respectively within one switching cycle, realizing energy transfer and active balancing between the battery modules.

[0071] Specifically, turn on the first group of array switches K. 2a-1 K2, K 2(a+1) Then, all other switches in the switch array are turned off, connecting the positive terminal of the first battery module a to one end of the first array resistor R, and the negative terminal of the first battery module a 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 becomes equal to the terminal voltage of the first battery module a; then, the second array switch K is turned on. 2b-1 K2, K 2(b+1)And all other switches in the switch array are turned off. At this time, the positive terminal of the second battery module b is connected to one end of the first array resistor R, and the negative terminal 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 this invention is not a complete mathematical equivalence, but includes numerical similarity or closeness. By alternately turning on the first array switch and the second array switch, 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 the alternating conduction of the two sets of switches. Here, the frequency of alternating conduction is called the second switch switching frequency fs. Furthermore, 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 have achieved balance. 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 refer to any two battery modules in the series-connected battery modules of this invention. Preferably, the two battery modules with the largest voltage difference are selected to begin balancing. The first set of array switches consists of: a switch connected between the positive terminal of the first battery module and the first switch array bus 1, a second array switch K2, and a switch connected between the negative terminal of the first battery module and the second switch array bus 2; the second set of array switches consists of: a switch connected between the positive terminal of the second battery module and the first switch array bus 1, a second array switch K2, and a switch connected between the negative terminal 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 aforementioned pattern, energy transfer between any two battery modules can be achieved, thereby realizing active balancing among all battery modules.

[0073] When the battery active balancing and battery impedance spectrum detection system operates in impedance spectrum detection mode, the first step is to achieve current excitation between battery modules. Specifically, taking the mutual generation of excitation current between the first battery module a and the second battery module b as an example, this invention illustrates the process of achieving current excitation between battery modules through energy exchange, enabling mutual excitation currents between the first battery module a and the second battery module b. In an embodiment of this invention, during the positive half-cycle of a switching cycle, the control module controls the conduction of the first array switch K via an excitation control signal. 2a-1 K2, K 2(a+1)All other switches in the switch array are in the off state. The positive terminal of the first battery module a is connected to one end of the first array resistor R, and the negative terminal of the first battery module a is connected to one end of the first array capacitor group C. Damped oscillations occur between the first battery module a and the R, L, C series branch, generating an excitation current. In the negative half-cycle of the same switching cycle, the control module controls the third array switch K corresponding to the second battery module b through the excitation control signal. 2b+1 K2, K 2b When the circuit is turned on, all other switches in the switch array are in the off state. The negative terminal of the second battery module b is connected to one end of the first array resistor R, and the positive terminal 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 series branch of R, L, and C generate excitation current through damped oscillation. In one switching cycle, the first array switch K is alternately turned on. 2a-1 K2, K 2(a+1) and the third array switch K 2b+1 K2, K 2b The control module alternately generates excitation currents on the first battery module a and the second battery module b. By controlling the branch switching control signal, the control module changes the capacitance value of the first array capacitor group C and the inductance value of the first array inductor group L, thereby altering the frequency of the damped oscillation and generating excitation currents of different frequencies. This, in turn, alternately turns on the first array switch K at the first switching frequency. 2a-1 K2, K 2(a+1) and the third array switch K 2b+1 K2, K 2b The switching operation continues until all batteries in the first battery module a and the second battery module b have completed impedance spectrum measurements, at which point the alternating switching operation ends. The third set of array switches consists of: a switch connected between the negative terminal of the second battery module b and the first switch array bus 1; a second array switch K2; and a switch connected between the positive terminal of the second battery module b and the second switch array bus 2. By changing the switching frequency of the first set of array switches and the third set of array switches through the control module, the duration of the excitation current generated on the battery module within one switching cycle can be changed, thus meeting the requirements for impedance spectrum detection.

[0074] Furthermore, by changing the values ​​of variables a and b, and following the aforementioned pattern, energy exchange between any two battery modules can be achieved, thereby generating the excitation current required for battery impedance spectrum measurement on each battery module in sequence.

[0075] Figure 2This is a schematic diagram of the internal structure of a battery module in a battery active balancing and battery impedance spectrum detection system according to an embodiment of the present invention. The internal structures of battery modules 1 through n are identical; battery module 1 is used as an example for explanation. As shown in the figure, batteries 1, ..., m are connected in series within battery module 1, where m is a non-negative integer greater than 1. The positive terminal of battery 1 is connected in series with a current acquisition unit to serve as the positive terminal of battery module 1, and the negative terminal of battery m serves as the negative terminal of battery module 1. The control unit controls the opening and closing of the switch in switch unit 1 through a first control signal. Let g be a variable that can take any non-negative integer value within the range 1 ≤ g ≤ m, where g represents the g-th battery in battery module 1. The positive terminal of battery g is connected to switch Q. 2g-1 Connected to the first switching unit bus 1, the negative terminal of battery g is connected to switch Q. 2g+1 Connected to the first switching unit bus 1, the negative terminal of battery g is connected to switch Q. 2(g+1) Connected to the second switch unit bus 2, except for battery 1, the positive terminal of battery g is connected to switch Q. 2g Connected to the second switch unit bus 2, each battery and each switch are connected in this manner. 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 terminal of battery 1 through the first unit switch Q1 and the second unit switch Q2, and the first unit capacitor C1 is connected through switch Q... 2(m+1) It is connected to the negative terminal of battery m.

[0076] In one embodiment, the method for achieving active balancing among the individual cells within a battery module is similar to the method for achieving active balancing between battery modules. For example... Figure 2 As shown, the process of balancing between batteries in this invention is illustrated using the method of balancing between the first battery g and the second battery h within battery module 1 as an example. The method of balancing between batteries in other battery modules is the same, and will not be described in detail to avoid redundancy. Figure 2 As shown, in battery module 1, the first battery g and the second battery h are selected. Preferably, the two batteries with the largest voltage difference are selected to begin balancing, but the balancing concept of this invention is not limited to this. Specifically, the first group of unit switches Q is turned on. 2g-1 Q2, Q 2(g+1) When the other switches in switch unit 1 are turned off, the positive terminal of the first battery g is connected to one end of the first unit resistor R1, and the negative terminal 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 becomes equal to the terminal voltage of the first battery g. This equality is not a perfect mathematical equality, but includes cases where the values ​​are close or similar. Further, the second set of unit switches Q is turned on. 2h-1 Q2, Q 2(h+1)When the other switches in switch unit 1 are turned off, the positive terminal of the second battery h is connected to one end of the resistor R1 in the first unit, and the negative terminal of the second battery h is connected to one end of the capacitor C1 in the first unit. After a period of time, the voltage across the capacitor C1 in the first unit becomes equal to the voltage across the second battery h. This equality is not a perfect mathematical equality; it includes cases where the values ​​are close or similar. This is achieved by alternately turning on the first set of unit switches Q. 2g-1 Q2, Q 2(g+1) Second group unit switch Q 2h-1 Q2, Q 2(h+1) This process transfers energy from the first battery (g) with a higher terminal voltage to the second battery (h) with a lower terminal voltage, thus achieving active balancing between the two batteries. The balancing mechanism among other batteries in the battery module is similar. The frequency of alternating conduction 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 indicates that balancing between them is complete. 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 set of unit switches consists of: a switch connected between the positive terminal of the first battery (g) and the first switch unit bus 1, a second unit switch Q2, and a switch connected between the negative terminal of the first battery (g) and the second switch unit bus 2. The second set of unit switches follows the same connection pattern.

[0077] In one embodiment, to better obtain the battery's impedance spectrum information, the battery detection requirements in online battery status monitoring include safety warnings, state of charge estimation, and health status estimation. Based on actual engineering conditions and requirements, the selected impedance characteristic frequency points are determined according to the required battery status detection quantities. Specifically, the selected characteristic frequency points can only be the damped oscillation frequencies 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 application, the possible value points of the first array inductor group L and the first array capacitor group C can be pre-designed to make the possible impedance characteristic frequency points as rich as possible and the impedance spectrum characteristic frequency points most valuable for battery status detection. For example, estimating the battery's internal temperature is an effective method for battery operation safety warnings. Therefore, for battery internal temperature estimation, multiple characteristic frequency points can be selected for impedance detection using a logarithmic scale equidistant point selection method within the 1000Hz-1Hz frequency range, which is sensitive to changes in battery internal temperature. For example, p characteristic frequency points needing impedance measurement can be selected, with p being 9. Taking the detection of the impedance spectrum of each battery in battery module 1 as an example, after generating an excitation current at the j-th characteristic frequency (variable j takes the value of each natural number in the range 1≤j≤p) on battery module 1, the control module sends an impedance spectrum detection command to the control unit in battery module 1. Figure 1(Not shown in the diagram), the control unit sends control commands to the current acquisition unit and each impedance spectrum measurement unit. The current flowing through each battery in 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 used for impedance spectrum measurement. Each battery's two ends are 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. Based on the voltage measurement data and the current measurement data, the impedance spectrum measurement unit calculates the real and imaginary parts of the impedance of the corresponding battery at the j-th characteristic frequency point.

[0078] In an embodiment of the present invention, the impedance spectrum measurement units within the battery module form a ring topology communication with the control unit via a daisy-chain communication method. Each impedance spectrum measurement unit receives control commands from the control unit and transmits the calculated real and imaginary impedance values ​​of each battery at the j-th characteristic frequency point to the control unit. Specifically, according to the impedance spectrum detection requirements, the value of variable j is changed, i.e., 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 passive devices. The impedance spectrum measurement units and the control unit measure and calculate the real and imaginary impedance values ​​of each battery at different characteristic frequency points through their structure and operating mode, and transmit them 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 sequence 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 receiving the impedance real and imaginary parts of each battery in the battery module at multiple frequencies, the control unit in each battery module calculates and organizes the impedance spectrum data of each battery in the corresponding battery module and transmits it to the control module. The control module then obtains the impedance spectrum information of each battery in each battery module.

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

[0082] In a preferred embodiment, the impedance spectrum measurement unit may consist of a commercially available single-cell management chip with integrated impedance measurement function and its peripheral circuitry.

[0083] Figure 3 This is a flowchart of the impedance spectrum detection method in a battery active equalization and battery impedance spectrum detection system and method according to an embodiment of the present invention. Figure 3 Combining Figure 1 and Figure 2 The impedance spectroscopy 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, and the number of battery modules n, where the number of battery modules n is the actual number of battery modules. Let the variable x, and let x = 1.

[0085] S2: Perform impedance spectrum analysis on battery module x. Let variable j be 1. Specifically, starting from battery module 1 in the series-connected battery modules, perform impedance spectrum analysis on each battery module. Here, variable j represents the j-th characteristic frequency point, and x represents the x-th battery module.

[0086] S3: The control module sends excitation control signals and branch switching control signals to control passive devices. According to the requirement of generating the excitation current at the j-th characteristic frequency, it 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. It performs switch switching control according to the first switch switching frequency to generate an excitation current on battery module x. The switching control method refers to the conduction and closing method of the switch when generating an excitation current on battery module a.

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

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

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

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

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

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

[0093] Figure 4 This is a flowchart of a battery equalization method in a battery active equalization and battery impedance spectrum detection system and method according to an embodiment of the present invention. The steps for equalization between battery modules and between batteries within a battery module are as follows:

[0094] S10: Set the second switch switching frequency fs, the first preset voltage Vs for the equalization termination threshold between battery modules, and the second preset voltage Vr for the equalization termination threshold between batteries within a battery module. Specifically, when the voltage difference between any two battery modules is less than the first preset voltage Vs, the equalization between battery modules ends; when the voltage difference between any two batteries within each battery module is less than the second preset voltage Vr, the equalization within the battery module ends.

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

[0096] S12: The control module controls the switch array to alternately conduct at the second switching frequency fs to achieve equalization. For details on the equalization method between the two battery modules, please 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 difference between any two series-connected battery modules is less than the first preset voltage Vs. Specifically, determine whether the voltage difference between any two battery modules is less than the first preset voltage Vs. If yes, execute S15; otherwise, return to execute S11.

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

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

[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. If 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 have completed balancing. Otherwise, return to S15 and continue the balancing operation until each battery in each battery module meets the balancing criteria.

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

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

[0105] The battery active balancing and battery impedance spectrum detection system and method disclosed in this invention can achieve active balancing and impedance spectrum detection functions using a single circuit system in a time-division multiplexing manner in a battery management system. Based on the control of passive devices, each battery module can periodically exchange electrical energy with the passive devices, enabling mutual current excitation between battery modules. This generates excitation currents at different frequencies required for impedance spectrum measurement on each battery sequentially. Based on the current acquisition unit, impedance spectrum measurement unit, and control unit, impedance spectrum detection and calculation of each battery in the battery system can be achieved with significant savings in system computing power. Based on the control of passive devices and switching units within the battery modules, active balancing between battery modules and between individual batteries within a battery module can also be achieved.

[0106] Those skilled in the art will readily understand that the above description is merely 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 within the scope of protection of the present invention.

Claims

1. A battery active balancing and battery impedance spectroscopy detection system, characterized in that, It comprises: a control module, a plurality of battery modules and a passive device, wherein the control module is connected with each battery module and the passive device, and each battery module is connected in series and connected in parallel with the passive device, the passive device comprises a switch array, a first array resistor, a first array inductor group, a first array pressure sensitive resistor and a first array capacitor group, wherein the first array inductor group is connected in parallel with the first array pressure sensitive resistor, and then connected 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 connected in parallel with the switch array; the switch array comprises a first switch array bus and a second switch array bus; for the a-th battery module, wherein a is a natural number from 1 to n, and n is the total number of battery modules, the positive electrode is connected to the first switch array bus through a switch, the negative electrode is connected to the first switch array bus through a switch, and the negative electrode is also connected to the second switch array bus through a switch; the positive electrode of the a-th battery module is also connected to the second switch array bus through a switch except for the first battery module; one end of the first array resistor is connected to the positive electrode of the first battery module through a switch, and one end of the first array capacitor group is connected to the negative electrode of the n-th battery module through a switch; 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 passageway between the battery module and the passive device, and through controlling the frequency of switch conduction, active balancing between each battery module is realized, wherein the frequency of switch conduction is the second switch switching frequency; and when the battery active balancing and battery impedance spectrum detection system works in the impedance spectrum detection mode, the control module sends an excitation control signal to the switch array in the passive device to control the passageway between the battery module and the passive device, and through controlling the frequency of switch conduction, the exchange of electric energy between the battery module and the passive device is realized, the excitation current required for impedance spectrum measurement is generated, and the impedance spectrum detection of the battery in the battery module is realized, wherein the frequency of switch conduction is the first switch switching frequency.

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 collection unit, a plurality of impedance spectrum measurement units, a passive unit, and a plurality of serially connected batteries. The control unit controls the switch unit in the passive unit through a first control signal. The current collection unit is used to collect the current flowing through the battery, and the collected current includes excitation currents at different frequencies required for impedance spectrum measurement. The impedance spectrum measurement unit is used to collect the terminal voltage of the battery and receive the battery current data from the current collection unit. The terminal voltage includes the response voltage of the excitation current at different frequencies on the battery. 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. The passive unit includes a switch unit, a first unit resistor, and a first unit capacitor. The first unit resistor and the first unit capacitor are connected in series and are connected in parallel with the switch unit. The switch unit includes a first switch unit bus and a second switch unit bus.

3. The battery active balancing and battery impedance spectroscopy detection system of claim 1, wherein, The passive device further includes a plurality of parallel inductance and switch branches in the first array inductance group, and the control module controls the change of the inductance value of the first array inductance group through a branch switching control signal. The first array capacitor group includes a plurality of parallel capacitor 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 spectroscopy detection system of claim 1, wherein, The first battery module and the second battery module in the plurality of battery modules achieve active balancing in the following manner: Turn on the first group of array switches, turn off the other switches in the switch array, connect the positive electrode of the first battery module to one end of the first array resistor, and connect the negative electrode of the first 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 first battery module. Turn on the second group of array switches, turn off the other switches in the switch array, connect the positive electrode of the second battery module to one end of the first array resistor, and connect 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 Alternately turn on the first group of array switches and the second group of array switches, so that the voltage difference between the first battery module and the second battery module is less than a first preset voltage. The first group of array switches includes switches connected between the positive electrode of the first battery module and the first switch array bus, the second array switch, and switches connected between the negative electrode of the first battery module and the second switch array bus. The second group of array switches includes switches connected between the positive electrode of the second battery module and the first switch array bus, the second array switch, and switches connected between the negative electrode of the second battery module and the second switch array bus.

5. The battery active balancing and battery impedance spectroscopy detection system of claim 1, wherein, The first battery module and the second battery module in the plurality of battery modules generate excitation currents through electric energy exchange in the following manner: Turning on the first group of array switches, turning off other switches in the switch array, connecting the positive pole of the first battery module to one end of the first array resistor, connecting the negative pole of the first battery module to one end of the first array capacitor group, and generating excitation current through damped oscillation between the first battery module and the passive device; Turning on the third group of array switches, turning off other switches in the switch array, connecting the negative pole of the second battery module to one end of the first array resistor, connecting the positive pole of the second battery module to one end of the first array capacitor group, and generating excitation current through damped oscillation between the second battery module and the passive device; and Alternately turning on the first group of array switches and the third group of array switches, wherein the first group of array switches includes: a switch connected between the positive pole of the first battery module and the first switch array bus, a second array switch, and a switch connected between the negative pole of the first battery module and the second switch array bus; and the third group of array switches includes: a switch connected between the negative pole of the second battery module and the first switch array bus, the second array switch, and a switch connected between the positive pole of the second battery module and the second switch array bus.

6. The battery active balancing and battery impedance spectroscopy detection system of claim 2, wherein, The first battery and the second battery in the battery module are actively balanced in the following manner: Turning on the first group of unit switches, turning off other switches in the switch unit, connecting the positive pole of the first battery to one end of the first unit resistor, connecting the negative pole of the first battery to one end of the first unit capacitor, and making the terminal voltage of the first unit capacitor equal to the terminal voltage of the first battery; Turning on the second group of unit switches, turning off other switches in the switch unit, connecting the positive pole of the second battery to one end of the first unit resistor, connecting the negative pole of the second battery to one end of the first unit capacitor, and making the terminal voltage of the first unit capacitor equal to the terminal voltage of the second battery; and Alternately turning on the first group of unit switches and the second group of unit switches to make the voltage difference between the first battery and the second battery less than a second preset voltage, wherein the first group of unit switches includes: a switch connected between the positive pole of the first battery and the first switch unit bus, a second unit switch, and a switch connected between the negative pole of the first battery and the second switch unit bus; and the second group of unit switches includes: a switch connected between the positive pole of the second battery and the first switch unit bus, the second unit switch, and a switch connected between the negative pole of the second battery and the second switch unit bus.

7. A method for detecting and calculating the impedance spectrum of a battery based on the battery active balancing and battery impedance spectrum detection system according to any one of claims 1-6, characterized in that, The method comprises the following steps: Step S1: determining the impedance spectrum sweep characteristic frequency points and the number of battery modules, wherein the number of characteristic frequency points p, the number of battery modules n, and x=1; Step S2: performing impedance spectrum detection on the battery module x in the battery module, and j=1; Step S3: the control module sends excitation control signal and branch switching control signal to control 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, controls the switch switching according to the first switch switching frequency, and generates the 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, and 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 Step S7: the control unit calculates the impedance spectrum of each battery in the battery module x; Step S8: if x Step S9: the control unit in all battery modules uploads the battery impedance spectrum data to the control module.

8. The method of claim 7, wherein the battery active balancing and battery impedance spectroscopy detection system detects and calculates the battery impedance spectroscopy. Also includes the first battery module and the second battery module in the plurality of battery modules generate excitation current through electric energy exchange, the specific way is as follows: Turn on the first group of array switches, turn off the other switches in the switch array, the positive electrode of the first battery module is connected with one end of the first array resistor, the negative electrode of the first battery module is connected with one end of the first array capacitor group, and the first battery module and the passive device occur damping oscillation to generate excitation current; Turn on the third group of array switches, turn off the other switches in the switch array, the negative electrode of the second battery module is connected with one end of the first array resistor, the positive electrode of the second battery module is connected with one end of the first array capacitor group, and the second battery module and the passive device occur damping oscillation to generate excitation current; And Alternately turn on the first group of array switches and the third group of array switches, 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 battery active balancing based on the battery active balancing and battery impedance spectroscopy detection system of any one of claims 1-6, characterized in that, Including the following steps: Step S10: set the second switch switching frequency, the battery module inter-equalization end threshold first preset voltage, and the battery inter-equalization end threshold second preset voltage; Step S11: select the first battery module and the second battery module in the series connected battery modules; Step S12: equalizing the first battery module and the second battery module, the control module controls the switch array to alternately conduct 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 performed, otherwise, step S12 is performed again; Step S14: determining whether the voltage difference between the battery modules is less than the first preset voltage, if yes, step S15 is performed, otherwise, step S11 is performed again; Step S15: selecting a first battery and a second battery in the battery module; Step S16: equalizing the first battery and the second battery in the battery module, the control unit controls the switch unit to alternately conduct 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, when the voltage difference between the first battery and the second battery is less than the second preset voltage, step S18 is performed, otherwise, step S16 is performed again; Step S18: determining 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 equalization is completed; otherwise, step S15 is performed again.

10. The method of claim 9, wherein the battery active balancing and battery impedance spectroscopy detection system implements the battery active balancing. The equalization steps of the first battery module and the second battery module are as follows: conducting a first group of array switches and turning off other switches in the switch array, so that the terminal voltage of a first array capacitor group is equal to the terminal voltage of the first battery module; conducting a 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; alternately conducting the first group of array switches and the second group of array switches at the second switch switching frequency, so that the voltage difference between the first battery module and the second battery module is less than the first preset voltage, wherein the first group of array switches comprises a switch connected between the positive electrode of the first battery module and a first switch array bus, a second array switch, and a switch connected between the negative electrode of the first battery module and a second switch array bus; the second group of array switches comprises 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 equalization steps of the first battery and the second battery in the battery module are as follows: conducting a first group of unit switches and turning off other switches in the switch unit, so that the terminal voltage of a first unit capacitor is equal to the terminal voltage of the first battery; conducting a 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 switching frequency, so that a voltage difference between the first battery and the second battery is less than a second preset voltage, wherein the first group of unit switches comprises: a switch connected between a positive electrode of the first battery and a first switching unit bus, a second unit switch, and a switch connected between a negative electrode of the first battery and a second switching unit bus; and the second group of unit switches comprises: a switch connected between a positive electrode of the second battery and the first switching unit bus, the second unit switch, and a switch connected between a negative electrode of the second battery and the second switching unit bus.

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