Lithium battery cell impedance measurement method and device based on module impedance switching, and storage medium

Abstract

According to the lithium battery monomer impedance measurement method and device based on module impedance switching and the storage medium provided by the invention, the module impedance switching technology is implemented on the battery string, and the impedance of each lithium battery monomer can be accurately measured, so that the safety and reliability of a battery system are improved. According to the method, the equalization resistor and the control switch are connected in parallel, and the impedance is flexibly switched on the battery string, so that the impedance of a single target battery cell can be accurately isolated and measured in the measurement process. Meanwhile, through the preset measurement time and the control signal of the PWM mode, the measurement process is further optimized, the accuracy and stability of measurement are ensured, and the battery cell is prevented from being burnt out due to the fact that large current passes through the battery cell for a long time.

Description

Technical Field

[0001] The present invention relates to the technical field of battery cell impedance measurement, and in particular to a lithium battery cell impedance measurement method, device and storage medium based on module impedance switching. Background Art

[0002] Lithium-ion batteries are commonly used in electric vehicles and energy storage power stations. However, their safety can deteriorate due to internal physical and chemical changes. It is crucial to monitor the condition of the battery, such as temperature, state of health (SOH), state of charge (SOC), and faults. Electrochemical impedance spectroscopy (EIS) can reflect the key status information of LIBs. Recently, many efforts have been made to realize electrochemical impedance spectroscopy (EIS) measurements of batteries. From the implementation point of view, they can be divided into three categories, namely offline, quasi-online and true online schemes, and the true online scheme can be implemented on-site in a real system. Typically, a low-amplitude excitation signal is injected into the battery, and the corresponding response signal is used to calculate the impedance. Nowadays, converter-based schemes have attracted widespread attention because the interface converter can easily modulate the excitation signal and the existing control sampling circuit can be directly used for response signal measurement. However, it can only measure the entire battery module or battery string, such as Figure 2 (a) Given the inconsistencies between individual cells, the EIS of an entire string / module cannot accurately reflect the state of a single cell. Fires and / or explosions in electric vehicles and ESPs typically begin in a single cell, subsequently igniting the entire module or string. Performing EIS measurements on individual cells is crucial to ensure safe battery system operation. Summary of the Invention

[0003] The present invention aims to at least solve the technical problem in the prior art that measuring the electrochemical impedance spectroscopy (EIS) of the entire string / module cannot accurately reflect the state of a certain battery cell. In particular, it innovatively proposes a lithium battery cell impedance measurement method, device and storage medium based on module impedance switching.

[0004] In order to achieve the above-mentioned object of the present invention, the present invention provides a lithium battery monomer impedance measurement method based on module impedance switching, the method comprising: S1, connect the excitation source in series at one end of the battery string; connect the balancing resistor in parallel to the target cell in the battery string , and the balancing resistor One end of the series control switch ; Each other battery cell in the battery string is connected in parallel with a balancing resistor , and each of the balancing resistors In series, the balancing resistors in each One end of the series control switch and an interface converter in parallel on the battery string; S2, opening the control switch , the balancing resistance is in the open state, the total impedance of the battery string and the impedance of the battery string except the target cell are collected; S3, closing the control switch , the balancing resistance is in the access state, the total impedance of the battery string and the impedance of the battery string except the target cell are collected again; S4, based on the total impedance of the battery string and the impedance of the battery string except the target cell collected in step S2, the impedance of the target cell is calculated according to the total impedance of the battery string and the impedance of the battery string except the target cell collected in step S3.

[0005] As an optional embodiment of the present application, optionally, the expression for calculating the impedance of the target cell is: wherein, represents the total impedance of the battery string collected after opening the control switch , represents the impedance of the battery string except the target cell collected after opening the control switch , represents the total impedance of the battery string collected after closing the control switch , represents the impedance of the battery string except the target cell collected after closing the control switch , represents the balancing resistance in parallel with the target cell on the battery string, represents and the difference between them.

[0006] As an optional embodiment of the present application, optionally, the method further comprises: the balancing resistance in series with the control switch is disconnected in the normal operation stage of the battery string, the control switch is closed in the stage of measuring the impedance of the target cell, and the control switch is disconnected within a preset measurement time, the control switch is closed, and the balancing resistance is controlled by a PWM mode control signal The control is performed.

[0007] As an optional embodiment of the present application, the measurement time is less than 5 seconds.

[0008] As an optional embodiment of the present application, the method further comprises: parallel low-resistance auxiliary equalization circuits on the battery string, and adjusting the resistance value at the target cell by using the low-resistance auxiliary equalization circuits.

[0009] As an optional embodiment of the present application, the low-resistance auxiliary equalization circuit comprises a group of regulation units, each of which is connected in parallel to each cell of the battery string, including a target cell, and each of which is connected in series to each other.

[0010] As an optional embodiment of the present application, the regulation unit comprises a regulation switch and a regulation resistance, and the regulation switch is connected in series to the regulation resistance.

[0011] As an optional embodiment of the present application, the resistance value of the regulation resistance is much smaller than the resistance value of each cell on the battery string.

[0012] In another aspect, the present application also provides a computer device, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to implement the above-mentioned lithium battery monomer impedance measurement method based on module impedance switching when executing the executable instructions.

[0013] In another aspect, the present application further provides a computer-readable storage medium, comprising: a memory having a computer program stored thereon; a processor for executing the program in the memory to implement the above-mentioned lithium battery monomer impedance measurement method based on module impedance switching.

[0014] The present application has the following advantages: the present application can accurately measure the impedance of each lithium battery monomer by implementing the module impedance switching technology on the battery string, thereby improving the safety and reliability of the battery system. The method can accurately isolate and measure the impedance of a single target cell during the measurement process by flexibly switching the impedance on the battery string through parallel equalization resistance and control switch. At the same time, the measurement process is further optimized by the pre-set measurement time and the control signal of the PWM mode, ensuring the accuracy and stability of the measurement and preventing the cell from being burned out due to long-time passing of large current.

[0015] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 This is a flow chart of a lithium battery cell impedance measurement method based on module impedance switching of the present invention; Figure 2 This is a schematic diagram of an impedance measurement method for a lithium battery cell based on module impedance switching of the present invention; Figure 3 This is a schematic diagram of electrochemical impedance spectroscopy (EIS) measurement of a lithium battery cell impedance measurement method based on module impedance switching of the present invention; Figure 4 The present invention is a lithium battery monomer impedance measurement method based on module impedance switching. Example schematic diagram; Figure 5 This is a schematic diagram of an example of verifying the electrochemical impedance spectroscopy (EIS) data of different batteries in a lithium battery cell impedance measurement method based on module impedance switching of the present invention.

[0017] Figure 6 This is a schematic diagram of an experimental device for measuring the impedance of a lithium battery cell based on module impedance switching of different batteries, using the LFP33135 battery as an example.

[0018] Figure 7 This is a schematic diagram of the measured EIS results of a lithium battery cell impedance measurement method based on module impedance switching for different batteries, taking LFP33135 batteries as an example, and a target battery cell in series. DETAILED DESCRIPTION

[0019] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0020] Example 1 like Figure 2As shown, currently, some cell-level electrochemical impedance spectroscopy (EIS) measurement schemes have been proposed. From the implementation point of view, these schemes can be divided into three categories, namely, multiplexer (MUX) based scheme, active balancing (AB) based scheme and analog front end (AFE) based scheme, as shown in Table 1. Figure 2 As shown in (b) to (d), it is known that the amplitude of the voltage excitation for EIS measurement is relatively small (usually in the order of millivolt). Therefore, additional hardware or specially designed circuits are usually required to implement cell-level EIS measurement, as shown in Table 1.

[0021] Comparison of typical EIS measurement schemes The purpose of the present application is that although the schemes in the literature can achieve cell-level measurement, additional hardware costs are generally required. According to market share reports, AFE chips have great application potential, but there are few commercially available at present. Meanwhile, passive balancing is still the main method in current industrial applications, such as chips from TI, ADI, etc. Considering the cost and other issues, passive balancing is generally used within a module, and active balancing is used between modules.

[0022] As shown in Figure 1 , a lithium battery cell impedance measurement method based on module impedance switching is used to solve the above technical problems.

[0023] The method comprises: S1, connecting an excitation source in series at one end of a battery string; connecting an equalization resistor in parallel on a target cell on the battery string , and connecting a control switch in series at one end of the equalization resistor ; connecting an equalization resistor in parallel on each cell on the battery string , and connecting a control switch in series at one end of each equalization resistor ; connecting a controller and an interface converter in parallel on the battery string . As shown in Figure 3 , it is necessary to explain that the control switch is used to control the connection and disconnection of the equalization resistor . When measuring the impedance of the target cell, the controller controls the control switch to be closed, so that the equalization resistor is connected to the circuit, thereby changing the impedance distribution of the battery string.

[0024] S2, open the control switch the balancing resistor is in the open state, the total impedance of the battery string and the impedance of the battery string excluding the target cell are collected; As Figure 3 shown in step S2, it needs to be explained that by opening the control switch , the balancing resistor is removed from the circuit, and other control switches are in the normally closed state, at which time the collected total impedance of the battery string and the impedance of the battery string excluding the target cell provide basic data for subsequent calculation. During this process, the interface converter is responsible for collecting impedance data and transmitting it to the controller for processing.

[0025] S3, close the control switch , so that the balancing resistor is in the access state, and the total impedance of the battery string and the impedance of the battery string excluding the target cell are collected again; As Figure 3 shown in step S3, it needs to be explained that by closing the control switch , the balancing resistor is connected to the circuit, and other control switches are in the normally closed state, at which time the impedance distribution of the battery string changes, and the impedance of the target cell is effectively isolated. The total impedance of the battery string and the impedance of the battery string excluding the target cell are collected again through the interface converter, and these data will be used for subsequent target cell impedance calculation.

[0026] S4, based on the total impedance of the battery string and the impedance of the battery string excluding the target cell collected in step S2, and the total impedance of the battery string and the impedance of the battery string excluding the target cell collected in step S3, the impedance of the target cell is calculated.

[0027] As Figure 3 shown in step S4, it needs to be explained that by comparing the impedance data collected in steps S2 and S3, the impedance value of the target cell can be accurately obtained using the impedance calculation formula provided below. This method not only improves the accuracy of measurement, but also realizes efficient and safe measurement of single cell impedance through flexible impedance switching technology.

[0028] The principle of the lithium battery cell impedance measurement method based on module impedance switching in this embodiment is: by connecting a balancing resistor and a control switch And flexibly switching the states of these impedance elements during the measurement process, precise measurement of the impedance of a single target cell can be achieved. During the measurement, first, the control switch corresponding to the target cell is disconnected, and the equalization resistor is in an open circuit state. At this time, the total impedance of the battery string and the impedance of the battery string excluding the target cell are collected as reference data. Subsequently, the control switch corresponding to the target cell is closed , the equalization resistor is connected to the circuit, the impedance distribution of the battery string is changed, and the total impedance of the battery string and the impedance of the battery string excluding the target cell are collected again. By comparing the impedance data collected twice, the impedance value of the target cell can be obtained by combining a specific impedance calculation formula. This method not only improves the accuracy of the measurement, but also avoids the cumbersome steps of disconnecting the battery string connection or adding additional measurement equipment in the traditional method, and realizes efficient and safe measurement of the impedance of a lithium battery cell.

[0029] As an optional embodiment of the present application, optionally, the expression for calculating the impedance of the target cell is: wherein, represents the total impedance of the battery string collected after the control switch is opened represents the impedance of the battery string excluding the target cell collected after the control switch is opened represents the total impedance of the battery string collected after the control switch is closed represents the impedance of the battery string excluding the target cell collected after the control switch is closed represents the equalization resistor in parallel with the target cell in the battery string, represents and the difference between them.

[0030] As an optional embodiment of the present application, optionally, the method further comprises: the equalization resistor the control switch connected in series at one end of the equalization resistor is disconnected during the normal operation stage of the battery string, the control switch is closed during the stage of measuring the impedance of the target cell, and the control switch is disconnected within a preset measurement time, and after the control switch is closed, a control signal in PWM mode is used to control the equalization resistor ​​​​Control is performed.

[0031] As Figure 3 shown, the PWM mode control signal can effectively adjust the access degree of the balancing resistance , thereby achieving fine adjustment of the battery string impedance. By presetting the measurement time, it can be ensured that the battery cell will not be burned out due to passing through a large current for a long time during the measurement process, further improving the safety and reliability of the measurement. In addition, the use of the PWM mode control signal can also reduce noise interference during the measurement process, improving the accuracy of the measurement. The specific resistance value of the balancing resistance needs to be much smaller than the resistance value of the target battery cell, so as to ensure that the influence of the balancing resistance on the overall impedance of the battery string can be accurately calculated and compensated during the measurement process. In this way, the accuracy and stability of the measurement can be further improved. In actual application, appropriate balancing resistance values and control switch types can be flexibly selected according to specific battery string configurations and measurement requirements to meet the measurement requirements in different scenarios.

[0032] As an optional embodiment of the present application, the measurement time is less than 5 seconds.

[0033] It should be noted that in the above embodiment, less than 5 seconds is selected as the measurement time, which is based on the comprehensive consideration of the accuracy and safety of the lithium battery single impedance measurement. This time range can not only ensure that the battery cell will not be burned out due to passing through a large current for a long time during the measurement process, but also can fully reflect the impedance change of the battery string, so as to obtain accurate measurement results. Of course, in actual application, the measurement time can be appropriately adjusted according to specific requirements and battery characteristics to achieve the best measurement effect.

[0034] As an optional embodiment of the present application, the method further comprises: parallelly connecting a low-resistance auxiliary balancing circuit on the battery string, and adjusting the resistance value at the target battery cell by using the low-resistance auxiliary balancing circuit.

[0035] It should be noted that the low-resistance auxiliary balancing circuit connected in parallel on the battery string can further optimize the measurement process. The low-resistance auxiliary balancing circuit can adjust the resistance value at the target battery cell during the measurement of the target battery cell impedance, so that the measurement process is more stable, and the measurement accuracy is improved. This design not only enhances the flexibility of the measurement, but also further improves the overall performance of the battery system.

[0036] As an optional embodiment of the present application, the low-resistance auxiliary balancing circuit comprises a group of adjusting units, each adjusting unit being connected in parallel on each battery cell of the battery string, including the target battery cell, and each adjusting unit being connected in series with each other.

[0037] As Figure 3 shown, it should be noted that each set of adjustment units includes a low resistance and a control switch. By controlling the closing and opening of the control switch , the resistance value at each cell can be flexibly adjusted. When measuring the impedance of the target cell, the corresponding control switch of the target cell is closed to connect the low resistance to the circuit, thereby reducing the resistance value at the target cell and optimizing the measurement process. This design not only improves the accuracy of the measurement, but also enhances the flexibility and stability of the battery system.

[0038] As an optional embodiment of the present application, optionally, the adjustment unit includes an adjustment switch and an adjustment resistance, and the adjustment switch is connected in series with the adjustment resistance.

[0039] As an optional embodiment of the present application, optionally, the resistance value of the adjustment resistance is much smaller than the resistance value of each cell on the battery string.

[0040] It should be noted that selecting the resistance value of the adjustment resistance to be much smaller than the resistance value of each cell on the battery string can ensure that the adjustment resistance has a greater impact on the overall impedance of the battery string during the measurement process, thereby more accurately reflecting the impedance change of the target cell. This design improves the accuracy of the measurement. Through the designed low-resistance auxiliary equalization circuit, the present application realizes efficient and accurate measurement of the impedance of the lithium battery cell.

[0041] As Figures 2 to 5 shown, the present embodiment can switch the impedance of the battery string with the equalization resistance and switch in the passive equalization circuit, and estimate the impedance of the target cell by analyzing the impedance difference before and after switching.

[0042] The specific principle is as follows: Figure 3 (a) shows a typical structure of a battery string with a passive equalization circuit, wherein - Ri and Ri+1 respectively represent equalization resistances, - Si and Si+1 respectively represent equalization switches, and V and I respectively represent the voltage and current of the battery string. The proposed method adjusts the impedance of the battery string by switching the parallel equalization resistances, so as to estimate the cell-level impedance based on the obtained change in the series impedance.

[0043] Let be the target cell that needs to be measured online by EIS, Figure 3 (b) shows the state when is closed (i.e., state I), then: wherein, represents the total impedance of the battery string, Represents node 0 and node -1 impedance, for The impedance, Figure 3 (c) shows The state when conducting (i.e. state II), here and In parallel, the total impedance of the battery string for: According to formulas (1) and (2), we can conclude that: in, for and By solving equation (3), It can be calculated as: It is worth noting that the calculated There are two solutions. The one with both real and imaginary parts being positive is selected as the true solution. The true solution is the estimated target cell. impedance.

[0044] Specific implementation process Figure 4 (d) shows the implementation flow chart of the proposed method. According to the basic principle of parallel impedance, the smaller The value can make the impedance difference between state I and state II more obvious, which is beneficial for impedance estimation. However, during measurement and normal equalization, power loss increases with In addition, when When conducting, low resistance will cause the battery current to be very large, which will affect the safety of the battery. To address this problem, two implementation solutions are proposed, namely a solution based on balancing resistors and a solution based on auxiliary balancing.

[0045] Solution based on balancing resistor: Figure 3 (e) shows the structure and control timing of the solution based on balancing resistors. This solution uses low-resistance balancing resistors, switches It is disconnected in state I or normal operation and closed in state II. It is worth noting that the fast impedance spectrum measurement method is used to avoid Long-term conduction leads to adverse effects on the battery, such as XXX (measurement time t mabout 5 seconds). In addition, considering that a low resistance is used, in order to avoid the adverse effects of large current discharging for a long time on the battery, The PWM mode needs to be controlled during the normal balancing state.

[0046] The auxiliary balancing-based scheme: Figure 3 (f) shows the structure of the auxiliary balancing-based scheme, which has a similar idea to the low-resistance balancing circuit scheme. This scheme adds a low-resistance auxiliary balancing circuit to the conventional balancing circuit and does not affect the normal balancing circuit design. During state II, the low-resistance auxiliary balancing circuit works, and by parallel connection , a smaller balancing resistance value is achieved (a smaller balancing resistance value can make the impedance difference between state I and state II more obvious, which is beneficial to impedance estimation), where - The resistance of - is much smaller than that of .

[0047] Switching resistance design: taking the balancing resistance-based scheme as an example, the design criteria for are given.

[0048] Assume that the number of cells in a battery string is , the impedance of each cell is , and only one cell is measured at a time. The balancing resistance during state II can be calculated as: where represents the change rate before and after impedance switching, i.e. ( - ) / .

[0049] During state II, the current of the cell must not exceed the specified maximum discharge current . Therefore, we have: where represents the battery voltage during state II.

[0050] Figure 4 (a) shows the EIS of PL7874172 (i.e. ) and IFR26650PE (i.e. ). It can be seen that the values of the direct current resistance and the maximum real impedance are similar. Therefore, in the calculation process, the To express (use To approximate ). On the other hand, taking IFR26650PE as an example, Figure 3 (a) The right side gives =2%, 5% and 10%, it can be found that a 2% change in impedance will lead to a difference in EIS, and the difference increases with increases with the increase of increases with the increase of ).

[0051] Table 3 Examples of typical commercial batteries for EVE Furthermore, taking EVE Energy Company as an example, Table 3 lists the parameters of its typical products, among which C 、 、 Represent capacity, maximum discharge current, and operating voltage respectively. It can be found that the internal resistance of the battery increases with the increase of its capacity. The maximum allowable discharge current of the power battery is relatively large. Based on formulas (5) and (6), Figure 4 (b)~4(d) show the three batteries at different battery voltages R n The calculation results of the figure show that the red area indicates that the current exceeds the maximum operating current, and the markings in the figure indicate ( , , ) value.

[0052] refer to Figure 4 (b)-4(c), The design guidelines can be summarized as follows: (1) The maximum value by and Reference Figure 4 (b) The top, when =1, NCM18650 is 11. However, when =2.3, Equal to 5.

[0053] (2) also by Decision. Reference Figure 2 (b) at the bottom, it can be seen that when =4.2V, is 7.

[0054] (3) Figure 4(c) as shown, the large capacity battery has a large resistance (e.g. LFPA41), leading to very low (e.g. 3.4 Ω), the current is large during measurement, thus the large capacity battery prefers to use active balancing, which is not suitable for this scheme.

[0055] (4) As shown in Figure 4 (d), the proposed scheme is suitable for LFP33135. However, there is a trade-off between , and .

[0056] (5) In general, this scheme is suitable for small and medium capacity batteries using passive balancing. In addition, since the power battery has a higher discharge rate than the energy storage battery, it is more suitable for this scheme.

[0057] EIS data validation: Take IFR26650PE battery as an example, Figure 5 (a) shows the EIS of 8 cells under different temperature and SOC conditions, where the blue dot represents the battery under test (BUT). Assuming that the 8 cells are connected in series, Figure 5 the gray line in (b) shows their total impedance. Assuming that a 0.2Ω resistor is connected in parallel with the BUT, Figure 5 the red line in (b) gives the total impedance. It can be seen that there is a difference in total impedance after the parallel resistor is enabled. In addition, the impedance at different frequencies can be solved based on equation (4).

[0058] Take LFP33135 battery as a case study, Figure 6 (a) shows the experimental setup built. In this setup, three cells are connected in series. The balancing circuit consists of a resistor Rb and a MOSFET, both of which are connected in parallel with the target cell. The circuit structure is shown in Figure 6 (a) at the bottom, where , and represent the series voltage, cell voltage and series / cell current, respectively.

[0059] Using an electrochemical impedance spectroscopy (EIS) measurement sequence, Figure 6 (b) shows the experimental waveforms under two conditions, i.e. vs、 and under condition I (balancing circuit not working) and condition II (balancing circuit enabled). Here, the length of a sequence is set to 1 second and five repeated injections are used to quickly measure EIS (i.e. total measurement time is 5 seconds). The measured EIS frequency range is 3Hz to 1000Hz.

[0060] Figure 7 (a) shows a battery pack (i.e. ) and the target cell (i.e. ) measured EIS results, where and Represent the real and imaginary parts of the impedance respectively. It can be seen that when the balancing circuit is enabled, the impedance of the series group and the cell both decreases. Based on the proposed estimation method, Figure 7 (b) shows the estimated EIS results of the target cell. The results show that the estimated EIS is almost consistent with the measured results.

[0061] In addition, taking six measurements as an example, Figure 7 (c) shows the normalized root mean square error (NRMSE) results for the estimated EIS amplitude and phase. It can be seen that the phase estimation error is relatively small, less than 1%. In the low- and mid-frequency range (i.e., 3 Hz-500 Hz), the amplitude error is less than 1.2%. However, due to the influence of line impedance, the amplitude error in the high-frequency range is larger.

[0062] Example 2 A computer device comprising: processor; a memory for storing processor-executable instructions; The processor is configured to implement a lithium battery cell impedance measurement method based on module impedance switching in Example 1 when executing the executable instructions.

[0063] It should be noted that the computer device includes: a processor, a memory, and may further include one or more of a multimedia component, an input / output (I / O) interface, and a communication component.

[0064] The processor is used to control the overall operation of the computer device to complete all or part of the steps in the above-mentioned lithium battery cell impedance measurement method based on module impedance switching.

[0065] The memory is used to store various types of data to support the operation of the computer device, which can include, for example, instructions for operating any application or method on the computer device, and application-related data; the memory can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0066] The multimedia component can include a screen, which can be a touch screen, for example, and an audio component for outputting and / or inputting audio signals; for example, the audio component can include a microphone for receiving external audio signals, and the received audio signals can be further stored in the memory or transmitted through the communication component; the audio component also includes at least one speaker for outputting audio signals.

[0067] The I / O interface provides an interface between the processor and other interface modules, which can be a keyboard, a mouse, a button, etc.; these buttons can be virtual buttons or physical buttons.

[0068] The communication component is used for wired or wireless communication between the computer device and other devices; wireless communication, such as Wi-Fi, Bluetooth, near field communication (NFC), 2G, 3G, 4G or 5G, or a combination of one or more of them, so the corresponding communication component can include a Wi-Fi module, a Bluetooth module, an NFC module, and a mobile communication module.

[0069] As a preferred scheme of the embodiment, the computer device can be implemented by one or more Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor or other electronic elements, for executing the above-mentioned lithium battery cell impedance measurement method based on module impedance switching.

[0070] Embodiment 3 A computer readable storage medium, comprising: a memory having a computer program stored thereon; a processor configured to execute the program in the memory to implement the lithium battery cell impedance measurement method based on module impedance switching in any one of the above-mentioned embodiments.

[0071] It should be noted that the electronic device of the embodiment of the present disclosure includes a processor and a memory for storing processor-executable instructions. Wherein, the processor is configured to execute the executable instructions to implement any one of the above-mentioned lithium battery cell impedance measurement methods based on module impedance switching.

[0072] It should be noted that the number of processors can be one or more. At the same time, the electronic device of the embodiment of the present disclosure can also include an input device and an output device. Wherein, the processor, the memory, the input device and the output device can be connected through a bus, or can be connected through other ways, which is not limited here.

[0073] The memory as a computer readable storage medium can be used to store software programs, computer executable programs and various modules, such as programs or modules corresponding to the lithium battery cell impedance measurement method based on module impedance switching of the embodiment of the present disclosure. The processor executes the software programs or modules stored in the memory, thereby executing various functional applications and data processing of the electronic device.

[0074] The input device can be used to receive input numbers or signals. Wherein, the signal can be a key signal related to the user settings and function control of the device / terminal / server. The output device can include a display device such as a display screen.

[0075] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the application. The scope of the application is not to be limited by the embodiments shown and described, but only by the claims and their equivalents.

Claims

1. A lithium battery cell impedance measurement method based on module impedance switching, characterized in that: The method comprises: S1, connect the excitation source in series at one end of the battery string; connect the balancing resistor in parallel to the target cell in the battery string , and the balancing resistor One end of the series control switch ; Each other battery cell in the battery string is connected in parallel with a balancing resistor , and each of the balancing resistors In series, the balancing resistors in each One end of the series control switch , and connecting a controller and an interface converter in parallel to the battery string; S2, turn on the control switch , so that the equalizing resistor In an open circuit state, collecting the total impedance of the battery string and the impedance of the battery string excluding the target battery cell; S3, turn on the control switch Close to make the equalizing resistor In the connected state, the total impedance of the battery string and the impedance of the battery string excluding the target battery cell are collected again; S4. Calculate the impedance of the target cell based on the total impedance of the battery string and the impedance of the battery string excluding the target cell acquired in step S2 and the total impedance of the battery string and the impedance of the battery string excluding the target cell acquired in step S3.

2. The lithium battery cell impedance measurement method based on module impedance switching according to claim 1, characterized in that: The expression for calculating the impedance of the target cell is: in, Indicates turning on the control switch Then collect the total impedance of the battery string, Indicates turning on the control switch Then, the impedance of the battery string except the target cell is calculated. express The impedance, Indicates that the switch will be controlled The total impedance of the battery string collected after closing, Indicates that the switch will be controlled The impedance of the battery string except the target cell collected after closing, Indicates the balancing resistor connected in parallel to the target cell in the battery string. express and The difference between .

3. The lithium battery cell impedance measurement method based on module impedance switching according to claim 1, characterized in that: The method further comprises: Equalizing resistor A control switch connected in series at one end The battery string is disconnected during normal operation, and the control switch is turned on during the impedance measurement of the target battery cell. Close and control the switch within the preset measurement time disconnect, in the control switch After closing, the balancing resistor is controlled by the PWM mode control signal. Take control.

4. The lithium battery cell impedance measurement method based on module impedance switching according to claim 3, characterized in that: The measurement time is less than 5 seconds.

5. The lithium battery cell impedance measurement method based on module impedance switching according to claim 1, characterized in that: The method further comprises: A low-resistance auxiliary balancing circuit is connected in parallel to the battery string, and the resistance value at the target battery cell is lowered by using the low-resistance auxiliary balancing circuit.

6. The lithium battery cell impedance measurement method based on module impedance switching according to claim 5, characterized in that: The low resistance auxiliary equalization circuit includes Groups of regulating units are respectively connected in parallel to each battery cell of the battery string, including the target battery cell, and each group of regulating units is connected in series.

7. The lithium battery cell impedance measurement method based on module impedance switching according to claim 6, characterized in that: The regulating unit includes a regulating switch and a regulating resistor, and the regulating switch is connected in series with the regulating resistor.

8. The lithium battery cell impedance measurement method based on module impedance switching according to claim 7, characterized in that: The resistance value of the regulating resistor is much smaller than the resistance value of each battery cell in the battery string.

9. A computer device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to implement the lithium battery cell impedance measurement method based on module impedance switching according to any one of claims 1 to 8 when executing the executable instructions.

10. A computer-readable storage medium, characterized in that include: a memory having a computer program stored thereon; A processor is used to execute the program in the memory to implement the lithium battery cell impedance measurement method based on module impedance switching according to any one of claims 1 to 8.

Images