A battery management system based on electrochemical impedance spectroscopy test

Abstract

The utility model discloses a kind of battery management system based on electrochemical impedance spectroscopy test.BMU battery management module includes MCU micro control unit, power supply and gateway unit;Gateway unit is connected with MCU micro control unit communication;BJB battery junction box is used to measure the current of battery pack, including BJB chip module and DC-DC module;BJB chip module is connected with gateway unit;DC-DC module is electrically connected with MCU micro control unit, power supply respectively by first MOS tube;BJB chip module includes first DFT discrete fourier transform unit;CMU battery monitoring unit is used to measure the voltage of battery monomer, including multiple AFE chip unit;AFE chip unit includes second DFT discrete fourier transform unit;MCU micro control unit is connected with the second MOS tube in external excitation module, and MCU micro control unit output PWM excitation signal to drive second MOS tube start.

Description

Technical Field

[0001] This utility model belongs to the field of battery management system technology, specifically relating to a battery management system based on electrochemical impedance spectroscopy testing. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) is an important research area in electrochemistry, showing great potential for application in battery state monitoring. EIS can detect key parameters such as changes in internal impedance, state of health (SOH), internal temperature, and electrode anomalies leading to lithium deposition. Real-time EIS measurement is also crucial in Battery Monitoring and Management Systems (BMS). EIS measurements can not only detect thermal runaway early but also provide internal impedance state information related to battery health throughout the battery's lifespan, providing a scientific basis for the rational use and maintenance of the battery. For example, Chinese Patent CN107076801B discloses an electrochemical impedance spectroscopy method for use in a battery management system, mentioning the use of EIS measurements in the system to determine the SOH of rechargeable batteries during use.

[0003] However, limited by current technology, implementing EIS measurements in a BMS faces numerous technical challenges and shortcomings. The measurement results obtained by existing technologies are far from ideal, and a series of problems remain to be solved, such as local Discrete Fourier Transform (DFT), communication data load rate, and synchronization of voltage and current measurements. Furthermore, existing technologies also have the following incompatibilities in BMS applications:

[0004] 1) Excessive communication load. To ensure the accuracy of EIS measurement results, the Analog Front End (AFE) needs to transmit a large amount of time-domain data to the Microcontroller Unit (MCU) so that the EIS measurement can obtain the correct frequency-domain results to plot the Nyquist curve. However, this will increase the load on the communication bus.

[0005] 2) Voltage and current measurements are difficult to synchronize. Frequency domain EIS measurement results include amplitude and phase information, with the magnitude of phase error primarily depending on the synchronization of voltage and current measurements. However, in practical systems, voltage and current measurements are typically located on different PCBs. Due to factors such as signal transmission delays and clock differences between different PCBs, achieving synchronization of voltage and current measurements is extremely difficult. If voltage and current measurements are not synchronized, it will lead to an increase in the phase error in the EIS measurement results, thereby affecting the accurate judgment of parameters such as the battery's internal impedance.

[0006] 3) Adverse effects of EIS excitation. EIS measurements require applying sinusoidal excitation to the battery; therefore, when a sinusoidal current is input to the battery, sinusoidal voltage feedback is obtained. Existing technologies generally employ two excitation schemes, both of which have significant shortcomings. Scheme one uses onboard excitation. Since the battery generates heat during operation, and onboard excitation devices have limitations in heat dissipation, the excitation current is restricted. Scheme two uses external excitation. This external excitation can come from a sinusoidal generator, such as in vehicle chargers or power conversion systems in industrial applications. While external excitation can provide a stronger excitation signal, it requires complex control logic to coordinate with the battery system, which undoubtedly increases the system's complexity and cost.

[0007] Therefore, how to effectively implement EIS measurement in BMS and overcome the difficulties such as excessively high communication load rate, difficulty in synchronizing voltage and current measurements, and adverse effects caused by EIS excitation has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the problems in related technologies, this invention proposes a battery management system based on electrochemical impedance spectroscopy (EIS) testing to overcome the aforementioned technical issues in existing technologies. Based on an AFE chip unit, a BJB chip module, and a gateway unit, this invention achieves real-time EIS measurement in the BMS and includes an easily implemented external excitation source. This excitation source is locally controlled by an MCU microcontroller unit, enabling this invention to overcome difficulties such as excessively high communication load, difficulty in synchronizing voltage and current measurements, and adverse effects caused by EIS excitation.

[0009] The technical solution of this utility model is implemented as follows: a battery management system based on electrochemical impedance spectroscopy, comprising:

[0010] A battery pack, comprising multiple battery cells connected in series;

[0011] The BMU battery management module includes an MCU microcontroller unit, a power supply, and a gateway unit connected in sequence; the gateway unit communicates with the MCU microcontroller unit through an SPI serial peripheral interface.

[0012] The BJB battery junction box is used to measure the current of the battery pack. It includes a BJB chip module and a DC-DC module that are electrically connected in sequence. The BJB chip module is connected to the gateway unit. The DC-DC module is electrically connected to the MCU microcontroller and the power supply through a first MOS transistor.

[0013] The DC-DC module is used to convert the high voltage output by the first MOSFET into a low voltage for use by the BJB chip module.

[0014] Furthermore, the DC-DC module is used to convert the 25V voltage output by the first MOSFET into a 9V voltage;

[0015] The BJB chip module includes a first DFT discrete Fourier transform unit, which is connected to the gateway unit via a TPL daisy chain. The first DFT discrete Fourier transform unit is used to convert the measured battery pack current signal into current DFT parameters. The individual cell current signal is transformed by the first DFT discrete Fourier transform unit to obtain current DFT parameters and then sent to the gateway unit.

[0016] Furthermore, the power supply outputs 12V to the first MOSFET, and also outputs 5V or 3.3V to the gateway unit and the MCU microcontroller unit, respectively.

[0017] The CMU (Cellular Unit) is used to measure the voltage of the individual battery cells. It includes multiple AFE (Automatic External Filter) chip units connected in series. Each AFE chip unit is connected to a corresponding individual battery cell. Each AFE chip unit includes a second DFT (Discrete Fourier Transform) unit, which is communicatively connected to a gateway unit via a TPL (Through-Purpose Layer) daisy chain. The second DFT unit converts the measured battery cell voltage signal into voltage DFT parameters. After transformation by the second DFT unit, the voltage parameters are obtained and sent to the gateway unit.

[0018] The external excitation module includes an excitation circuit, which includes a second MOSFET; the MCU microcontroller unit is connected to the second MOSFET, and the MCU microcontroller unit outputs a PWM excitation signal to drive the second MOSFET to start; the external excitation module is connected to the positive and negative terminals of the battery pack respectively.

[0019] The gateway unit is used to distribute a synchronization clock signal to the AFE chip unit, and at the same time, it is used to receive current DFT parameters and voltage DFT parameters and forward them to the MCU microcontroller unit.

[0020] Furthermore, the current sampling operation of the BJB chip module is triggered by a synchronization signal from the gateway unit or an instruction from the MCU microcontroller unit, ensuring synchronization with the voltage sampling time of the CMU;

[0021] Preferably, in this invention, the time deviation between the voltage sampling time and the current sampling time is ≤150 nanoseconds;

[0022] The MCU microcontroller unit calculates the electrochemical impedance spectrum of a single cell based on synchronized voltage DFT and current DFT parameters.

[0023] Furthermore, it also includes a shunt, a main negative contact switch, and a main positive contact switch; the battery pack, shunt, main negative contact switch, external excitation module, and main positive contact switch are connected in sequence to form a battery circuit;

[0024] It also includes a pre-charge contact switch and a fourth load resistor connected in series, wherein the pre-charge contact switch and the fourth load resistor are connected in parallel across the main positive contact switch;

[0025] Furthermore, the main positive contact switch is connected to the positive terminal of the battery pack, and the main negative contact switch is connected to the negative terminal of the battery pack.

[0026] Furthermore, the BJB chip module is connected in parallel across the two ends of the shunt, and the battery pack is communicatively connected to the PRMADC interface of the BJB chip module.

[0027] Furthermore, the excitation circuit also includes a fuse, a first load resistor, a second load resistor, and a third load resistor;

[0028] The second MOS transistor is an OPTO-MOS transistor, and an optocoupler unit is integrated within the second MOS transistor; the optocoupler unit includes a photodiode and a phototransistor; one end of the photodiode is connected to the MCU microcontroller unit, and the other end is grounded;

[0029] It should be noted that the OPTO-MOS transistor is a device that integrates or combines an optocoupler (OPTO) with a power MOSFET transistor; in this invention, the optocoupler unit is an optocoupler.

[0030] One end of the fuse is connected to the main positive contact switch, and the other end is connected to the first load resistor; the first load resistor is connected to the source of the second MOSFET, and the drain of the second MOSFET is connected to the main negative contact switch; one end of the third load resistor is connected to the gate of the second MOSFET, and the other end is connected to the main negative contact switch; one end of the second load resistor is connected to the first load resistor, and the other end is connected to the phototransistor.

[0031] The MCU microcontroller unit sends a PWM excitation signal to the photodiode, and the PWM excitation signal is a sine wave signal; under the drive of the PWM excitation signal, the first load resistor in the excitation circuit generates the target current;

[0032] It should be further noted that the external excitation module in this utility model is locally controlled by the MCU microcontroller unit, and the excitation circuit includes an OPTO-MOS transistor and a first load resistor, which can support a maximum excitation current of 10A.

[0033] Furthermore, the DC-DC module is connected to the drain of the first MOS transistor, the MCU microcontroller is connected to the gate of the first MOS transistor, and the source of the first MOS transistor is connected to the power supply.

[0034] Furthermore, the BJB chip module includes a BJB chip of model ADBMS2970.

[0035] Furthermore, each of the AFE chip units includes an AFE chip of model ADBMS6843; the battery cell is correspondingly connected to the ADC interface of the AFE chip unit.

[0036] Furthermore, the gateway unit includes a first transceiver, and the MCU microcontroller unit includes a second transceiver, with the first transceiver and the second transceiver being communicatively connected; each of the transceivers is an ADBMS6821 or an ADBMS6822.

[0037] Furthermore, the BJB chip module integrates a first register for storing current DFT parameters; the AFE chip unit integrates a second register for storing voltage DFT parameters.

[0038] Furthermore, the MCU microcontroller unit integrates a verification unit, which is used to verify the AAF parameters (anti-aliasing filter parameters) and CIC parameters (combing filter parameters).

[0039] The beneficial effects of this utility model are:

[0040] (1) The AFE chip unit and BJB battery junction box of this utility model adopt the local DFT discrete Fourier transform technology, that is, by setting the first DFT discrete Fourier transform unit and the second DFT discrete Fourier transform unit, the communication bus load is effectively reduced.

[0041] (2) In this invention, the time deviation between the voltage sampling time and the current sampling time is ≤150 nanoseconds, which realizes a high degree of synchronization between voltage and current measurement.

[0042] (3) In the battery management system of this utility model, the amplitude accuracy of the frequency domain measurement result obtained by EIS measurement is <1%, the phase accuracy of the frequency domain measurement result is <±0.4°, and the external excitation module can support excitation frequency of 0.1~1kHz, which can cover the application range of EIS.

[0043] (4) Based on the AFE chip unit, BJB chip module and gateway unit, this utility model realizes the real-time measurement of EIS in BMS and includes an easy-to-implement external excitation source; the external excitation module is locally controlled by the MCU microcontroller unit, and the excitation circuit includes an OPTO-MOS transistor and a first load resistor, which can support a maximum excitation current of 10A. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the system structure of the battery management system of this utility model;

[0045] Figure 2 This is a system block diagram of the battery management system of this utility model;

[0046] Figure 3 This is a flowchart of the EIS measurement software for the battery management system of this utility model;

[0047] Figure 4 This is a graph showing the accuracy error of the EIS measurement results for a 100Ah lithium iron phosphate battery according to this invention. Detailed Implementation

[0048] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0049] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0050] like Figure 1-3 As shown, this embodiment provides a battery management system based on electrochemical impedance spectroscopy, including:

[0051] A battery pack, comprising multiple battery cells connected in series;

[0052] The BMU battery management module includes an MCU microcontroller unit, a power supply, and a gateway unit connected in sequence; the gateway unit communicates with the MCU microcontroller unit through an SPI serial peripheral interface.

[0053] The BJB battery junction box is used to measure the current of the battery pack. It includes a BJB chip module and a DC-DC module that are electrically connected in sequence. The BJB chip module is connected to the gateway unit. The DC-DC module is electrically connected to the MCU microcontroller and the power supply through a first MOS transistor.

[0054] The DC-DC module is used to convert the high voltage output by the first MOSFET into a low voltage for use by the BJB chip module.

[0055] More specifically, the DC-DC module is used to convert the 25V voltage output by the first MOSFET into a 9V voltage;

[0056] More specifically, the power supply outputs 12V to the first MOSFET, and outputs 5V or 3.3V to the gateway unit and the MCU microcontroller unit, respectively.

[0057] The BJB chip module includes a first DFT (Discrete Fourier Transform) unit, which is connected to the gateway unit via a TPL daisy chain. The first DFT unit is used to convert the measured battery pack current signal into current DFT parameters (i.e., to convert the time-domain signal of the current into the frequency-domain signal of the current). The individual cell current signal is transformed by the first DFT unit to obtain the current DFT parameters and then sent to the gateway unit.

[0058] The CMU (Battery Monitoring Unit) is used to measure the voltage of the individual battery cells. It includes multiple AFE (Automatic Factor Transfer) chip units connected in series. Each AFE chip unit is connected to a corresponding individual battery cell. Each AFE chip unit includes a second DFT (Discrete Fourier Transform) unit, which is connected to a gateway unit via a TPL (Telematics Propagation Layer) daisy chain. The second DFT unit converts the measured battery cell voltage signal into voltage DFT parameters (i.e., transforms the time-domain voltage signal into a frequency-domain voltage signal). After the battery cell voltage signal is transformed by the second DFT unit, the voltage DFT parameters are obtained and sent to the gateway unit.

[0059] This embodiment can effectively reduce the communication bus load by setting the first DFT discrete Fourier transform unit and the second DFT discrete Fourier transform unit.

[0060] The external excitation module includes an excitation circuit, which includes a second MOSFET; the MCU microcontroller unit is connected to the second MOSFET, and the MCU microcontroller unit outputs a PWM excitation signal to drive the second MOSFET to start; the external excitation module is connected to the positive and negative terminals of the battery pack respectively.

[0061] The gateway unit is used to distribute a synchronization clock signal to the AFE chip unit, and at the same time, it is used to receive current DFT parameters and voltage DFT parameters and forward them to the MCU microcontroller unit.

[0062] More specifically, the current sampling operation of the BJB chip module is triggered by a synchronization signal from the gateway unit or an instruction from the MCU microcontroller unit to ensure synchronization with the voltage sampling time of the CMU;

[0063] Preferably, in this embodiment, the time deviation between the voltage sampling time and the current sampling time is ≤150 nanoseconds;

[0064] The MCU microcontroller unit calculates the electrochemical impedance spectrum of a single cell based on synchronized voltage DFT and current DFT parameters.

[0065] Specifically, it also includes a shunt, a main negative contact switch, and a main positive contact switch; the battery pack, shunt, main negative contact switch, external excitation module, and main positive contact switch are connected in sequence to form a battery circuit;

[0066] It also includes a pre-charge contact switch and a fourth load resistor connected in series, wherein the pre-charge contact switch and the fourth load resistor are connected in parallel across the main positive contact switch;

[0067] More specifically, the main positive contact switch is connected to the positive terminal of the battery pack, and the main negative contact switch is connected to the negative terminal of the battery pack.

[0068] Specifically, the BJB chip module is connected in parallel across the two ends of the shunt, and the battery pack is communicatively connected to the PRMADC interface of the BJB chip module.

[0069] Specifically, the excitation circuit further includes a fuse, a first load resistor, a second load resistor, and a third load resistor;

[0070] The second MOS transistor is an OPTO-MOS transistor, and an optocoupler unit is integrated within the second MOS transistor; the optocoupler unit includes a photodiode and a phototransistor; one end of the photodiode is connected to the MCU microcontroller unit, and the other end is grounded;

[0071] It should be noted that the OPTO-MOS transistor is a device that integrates or combines an optocoupler (OPTO) with a power MOSFET transistor; in this embodiment, the optocoupler unit is an optocoupler.

[0072] One end of the fuse is connected to the main positive contact switch, and the other end is connected to the first load resistor; the first load resistor is connected to the source of the second MOSFET, and the drain of the second MOSFET is connected to the main negative contact switch; one end of the third load resistor is connected to the gate of the second MOSFET, and the other end is connected to the main negative contact switch; one end of the second load resistor is connected to the first load resistor, and the other end is connected to the phototransistor.

[0073] The MCU microcontroller unit sends a PWM excitation signal to the photodiode, and the PWM excitation signal is a sine wave signal; under the drive of the PWM excitation signal, the first load resistor in the excitation circuit generates the target current;

[0074] It should be further noted that the external excitation module in this embodiment is locally controlled by the MCU microcontroller unit, and the excitation circuit includes an OPTO-MOS transistor and a first load resistor, which can support a maximum excitation current of 10A.

[0075] Specifically, the DC-DC module is connected to the drain of the first MOS transistor, the MCU microcontroller is connected to the gate of the first MOS transistor, and the source of the first MOS transistor is connected to the power supply.

[0076] Specifically, the BJB chip module includes a BJB chip with model number ADBMS2970.

[0077] Specifically, each of the AFE chip units includes an AFE chip of model ADBMS6843; the battery cell is connected to the ADC interface of the AFE chip unit.

[0078] Specifically, the gateway unit includes a first transceiver, and the MCU microcontroller unit includes a second transceiver. The first transceiver and the second transceiver are communicatively connected. The transceiver is either an ADBMS6821 or an ADBMS6822.

[0079] Specifically, the BJB chip module integrates a first register for storing current DFT parameters; the AFE chip unit integrates a second register for storing voltage DFT parameters.

[0080] Specifically, the MCU microcontroller unit integrates a verification unit, which is used to verify the AAF parameters (anti-aliasing filter parameters) and CIC parameters (combing filter parameters).

[0081] The specific operation process of the battery management system based on electrochemical impedance spectroscopy is as follows:

[0082] Step 1: The MCU (Microcontroller Unit) performs system initialization, which means configuring and starting some basic functions after the entire system is powered on.

[0083] Step 2: Enable the synchronous acquisition function of voltage and current for the CMU battery monitoring unit and BJB battery junction box, with an acquisition time of 50-100ms.

[0084] Step 3: Check whether enabling and disabling the voltage and current synchronous acquisition function is normal; and disable the voltage and current synchronous acquisition function.

[0085] Step 4: After a 5ms delay, configure the waiting time required for all nodes on the two TPL daisy chains (generally 3.84ms), and then enable the voltage and current synchronization acquisition function again.

[0086] Step 5: Based on the target's test frequency (the number of test frequency sampling points is not limited), set the number of sampling test frequency points used when performing EIS measurement, and configure the parameters of the Discrete Fourier Transform (i.e., set the frequency of the Discrete Fourier Transform).

[0087] Step 6: Based on the parameters of the Discrete Fourier Transform (i.e. the frequency of the Discrete Fourier Transform) obtained in Step 5, configure the frequency of the Discrete Fourier Transform in the first DFT Discrete Fourier Transform unit of the BJB chip module, and configure the frequency of the Discrete Fourier Transform in the second DFT Discrete Fourier Transform unit of the AFE chip unit to ensure that the Discrete Fourier Transform frequency of voltage and current sampling is consistent with the target test frequency.

[0088] Step 7: Enable the external stimulus module;

[0089] Step 8: Verify whether the external excitation frequency is consistent with the target test frequency (i.e., verify the AAF parameters and CIC parameters);

[0090] Step 9: If the external excitation frequency is inconsistent with the target test frequency, then perform correction (that is, correct the discrete Fourier transform frequency of the external excitation to be consistent with the target test frequency).

[0091] Step 10: After the external excitation configuration is completed (i.e., after confirming the external excitation frequency), wait for one sampling period (usually 0.1s);

[0092] Step 11: The AFE chip unit performs voltage measurement, obtains the time-domain measurement result V(t) of the voltage, and performs Discrete Fourier Transform through the second DFT Discrete Fourier Transform unit to finally obtain the frequency-domain measurement result V(f) of the voltage and store it in the second register; at the same time, the BJB chip module performs current measurement, obtains the time-domain measurement result I(t) of the current, and performs Discrete Fourier Transform through the first DFT Discrete Fourier Transform unit to finally obtain the frequency-domain measurement result I(f) of the current and store it in the first register;

[0093] Step 12: Each memory transmits the frequency domain measurement results to the gateway unit via a TPL daisy chain; the gateway unit uploads the frequency domain measurement results of voltage and current to the MCU microcontroller unit via the first transceiver and the second transceiver unit; the MCU microcontroller unit performs filtering, shaping and compensation processing on the data;

[0094] Step 13: Calculate the AC impedance of each battery cell in the MCU microcontroller unit using the formula Z(f)=V(f) / I(f) and plot the corresponding Nyquist curve;

[0095] Step 14: Correct and compensate the measurement results using EIS measurement software, mainly to correct and compensate for measurement errors caused by wiring harnesses and connectors;

[0096] Step 15: Correction complete, EIS test finished.

[0097] In the battery management system of this embodiment, the amplitude accuracy of the frequency domain measurement results obtained by EIS measurement is <1%, the phase accuracy of the frequency domain measurement results is <±0.4°, and the external excitation module can support an excitation frequency of 0.1 to 1 kHz (even if an external excitation of 0.1 Hz is applied, excitation can be detected).

[0098] An external excitation current of 2.5A was applied as a preset value, and then an EIS measurement was performed on a 100Ah lithium iron phosphate battery. The measurement results are as follows: Figure 4 As shown; where the real and imaginary parts of the AC impedance displayed by the EIS measurement results were selected from multiple test frequencies, namely 1 Hz, 8 Hz, 10 Hz, 40 Hz, 80 Hz, 100 Hz, 250 Hz, and 450 Hz.

[0099] Specifically, taking a test frequency of 1 Hz as an example, when the test frequency is 1 Hz, the measurement error of the real part of the AC impedance displayed by the EIS measurement result is smaller than the measurement error of its imaginary part.

[0100] And in Figure 4 In the EIS measurement results, the measurement errors of the real and imaginary parts of the AC impedance are both below 2 μOhm (i.e., 2 microohms), which proves that the battery management system of this embodiment has good EIS measurement performance.

[0101] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, this utility model is not limited to the specific embodiments disclosed and described above, and some modifications and changes to this utility model should also fall within the protection scope of the claims of this utility model. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on this utility model.

Claims

1. A battery management system based on electrochemical impedance spectroscopy, characterized in that, include: A battery pack, comprising multiple battery cells connected in series; The BMU battery management module includes an MCU microcontroller unit, a power supply, and a gateway unit that are connected in sequence. The gateway unit communicates with the MCU microcontroller unit via an SPI serial peripheral interface. The BJB battery junction box is used to measure the current of the battery pack. It includes a BJB chip module and a DC-DC module that are electrically connected in sequence. The BJB chip module is connected to the gateway unit. The DC-DC module is electrically connected to the MCU microcontroller and the power supply through a first MOS transistor. The DC-DC module is used to convert the high voltage output by the first MOSFET into a low voltage. The BJB chip module includes a first DFT discrete Fourier transform unit, which is connected to the gateway unit via a TPL daisy chain; the first DFT discrete Fourier transform unit is used to convert the measured battery pack current signal into current DFT parameters. The CMU (Cellular Unit) is used to measure the voltage of the individual battery cells. It includes multiple AFE (Automatic Factor Transfer) chip units connected in series. Each AFE chip unit is connected to each individual battery cell. Each AFE chip unit includes a second DFT (Discrete Fourier Transform) unit, which is connected to a gateway unit via a TPL (Through a daisy chain). The second DFT unit is used to convert the measured battery cell voltage signal into voltage DFT parameters. The external excitation module includes an excitation circuit, which includes a second MOSFET; the MCU microcontroller unit is connected to the second MOSFET, and the MCU microcontroller unit outputs a PWM excitation signal to drive the second MOSFET to start; the external excitation module is connected to the positive and negative terminals of the battery pack respectively.

2. The battery management system according to claim 1, characterized in that, It also includes a shunt, a main negative contact switch, and a main positive contact switch; the battery pack, shunt, main negative contact switch, external excitation module, and main positive contact switch are connected in sequence to form a battery circuit; It also includes a pre-charge contact switch and a fourth load resistor connected in series, wherein the pre-charge contact switch and the fourth load resistor are connected in parallel across the main positive contact switch.

3. The battery management system according to claim 2, characterized in that, The BJB chip module is connected in parallel across the two ends of the shunt, and the battery pack is communicatively connected to the PRMADC interface of the BJB chip module.

4. The battery management system according to claim 2, characterized in that, The excitation circuit also includes a fuse, a first load resistor, a second load resistor, and a third load resistor; The second MOS transistor is an OPTO-MOS transistor, and an optocoupler unit is integrated within the second MOS transistor; the optocoupler unit includes a photodiode and a phototransistor; one end of the photodiode is connected to the MCU microcontroller unit, and the other end is grounded; One end of the fuse is connected to the main positive contact switch, and the other end is connected to the first load resistor; the first load resistor is connected to the source of the second MOSFET, and the drain of the second MOSFET is connected to the main negative contact switch. One end of the third load resistor is connected to the gate of the second MOS transistor, and the other end is connected to the main negative contact switch; One end of the second load resistor is connected to the first load resistor, and the other end is connected to the phototransistor.

5. The battery management system according to claim 1, characterized in that, The DC-DC module is connected to the drain of the first MOS transistor, the MCU microcontroller is connected to the gate of the first MOS transistor, and the source of the first MOS transistor is connected to the power supply.

6. The battery management system according to claim 1, characterized in that, The BJB chip module includes a BJB chip of model ADBMS2970.

7. The battery management system according to claim 1, characterized in that, Each of the AFE chip units includes an AFE chip of model ADBMS6843; the battery cell is connected to the ADC interface of the AFE chip unit.

8. The battery management system according to claim 1, characterized in that, The gateway unit includes a first transceiver, and the MCU microcontroller unit includes a second transceiver. The first transceiver and the second transceiver are communicatively connected. The transceiver is either ADBMS6821 or ADBMS6822.

9. The battery management system according to claim 1, characterized in that, The BJB chip module integrates a first register for storing current DFT parameters; the AFE chip unit integrates a second register for storing voltage DFT parameters.

10. The battery management system according to claim 1, characterized in that, The MCU microcontroller unit integrates a verification unit, which is used to verify the AAF parameter and the CIC parameter.

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