Broadband-domain EIS excitation-acquisition fusion architecture for battery pack

Abstract

The invention discloses a wide-frequency-domain EIS excitation-acquisition fusion framework for a battery pack, and belongs to the technical field of battery testing. The problems that an existing EIS test depends on a laboratory special instrument, is only suitable for a single battery offline test, is insufficient in excitation signal stability, and is high in high-frequency measurement cost are solved. Based on a closed-loop dynamic steady-current control technology and a direct-current bias dynamic zero setting technology, the system comprises an excitation injection and power conditioning module, a signal acquisition and front-end conditioning module, an isolation and channel switching module and a digital control and signal processing module. Through collaborative design of closed-loop dynamic steady-current control and a direct-current bias dynamic zeroing technology, high-resolution acquisition of weak impedance signals under a low-precision and high-speed ADC condition is realized while the stability of excitation signals is ensured; in combination with the isolation and channel switching module, parallel online EIS testing of multiple single batteries is realized, connection between a battery pack and an original power utilization system does not need to be disconnected in the testing process, and system hardware cost and integration difficulty are effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery testing technology, specifically relating to a wideband EIS excitation-acquisition fusion architecture for battery packs, which is suitable for online impedance monitoring of battery packs in engineering scenarios such as electric vehicles and energy storage systems. Background Technology

[0002] EIS, as a non-destructive testing technology, can effectively analyze the internal resistance, interface reaction and internal electrochemical characteristics of batteries. It is an important technical means to study the internal dynamic behavior of batteries and assess the state of health (SOH) and abnormal states of batteries. It has important value in the entire process of battery research and development, production and engineering application.

[0003] With the rapid development of electric vehicles, grid-scale energy storage systems, and other fields, the engineering application of large-capacity battery packs is becoming increasingly widespread, making the demand for online condition monitoring and health assessment of battery packs more and more urgent. As a detection method that can provide rich frequency domain information, EIS technology has great potential for application in the engineering monitoring of battery packs. However, existing EIS testing technologies still have many bottlenecks, which seriously limit their engineering implementation.

[0004] Existing EIS testing technologies mainly rely on laboratory-specific instruments, which are bulky, expensive, and only suitable for offline testing of individual cells. During testing, the battery pack must be disconnected from the operating system, making it impossible to acquire impedance information online when the battery pack is running normally and the load is dynamically changing. This makes it difficult to meet the needs of real-time monitoring of engineered battery packs. At the same time, large-capacity batteries and battery packs in electric vehicles and energy storage systems have characteristics such as low internal resistance (usually in the micro-ohm range), weak impedance response signals (in the micro-volt range), and complex operating conditions (alternating charging and discharging states, frequent load fluctuations). To achieve wide-frequency domain EIS testing, especially impedance measurement in the high-frequency range, it is often necessary to rely on high-speed, high-precision ADCs for synchronous acquisition. However, high-speed, high-precision ADCs are not only expensive but also consume a lot of power, making it difficult to achieve multi-channel large-scale deployment in large-scale battery pack systems. This significantly increases the hardware cost and integration difficulty of battery pack online monitoring systems.

[0005] Furthermore, existing EIS testing systems struggle to stably superimpose AC disturbance signals onto the real-time charge and discharge current of batteries in online operation scenarios. The amplitude and waveform of the excitation signal are prone to drift with changes in load conditions, resulting in low impedance measurement accuracy. Simultaneously, the battery has a large DC operating point during real-time charge and discharge, and weak AC response signals are easily masked by DC bias components. In the acquisition link of low-cost, high-speed ADCs, it is difficult to achieve high-resolution acquisition of weak signals, further limiting the promotion of wideband EIS technology in battery pack engineering applications.

[0006] Therefore, there is an urgent need for a wide-frequency domain EIS excitation-acquisition technology solution that can realize parallel online testing of multiple cells in a battery pack, balance test accuracy and cost control, and adapt to complex operating conditions, so as to provide reliable technical support for the engineering deployment of online impedance monitoring systems for battery packs. Summary of the Invention

[0007] The purpose of this invention is to address the technical problems of existing EIS testing technologies in battery pack engineering applications, such as difficulties in online testing, unstable excitation signals, low accuracy of weak signal acquisition, high hardware costs, and difficulty in parallel testing of multiple individual cells. Based on closed-loop dynamic current stabilization control technology and DC bias dynamic zeroing technology, this invention provides a wideband EIS excitation-acquisition fusion architecture for battery packs, enabling parallel online wideband EIS testing of multiple individual cells, reducing system hardware costs, improving testing accuracy and stability, and meeting the application requirements of engineering scenarios such as electric vehicles and energy storage systems.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A wideband EIS excitation-acquisition fusion architecture for battery packs is constructed based on closed-loop dynamic current stabilization control technology and DC bias dynamic zeroing technology, including an excitation injection and power conditioning module, a signal acquisition and front-end conditioning module, an isolation and channel switching module, and a digital control and signal processing module.

[0010] One end of the excitation injection and power conditioning module is electrically connected to the digital control and signal processing module to receive its control commands, and the other end is electrically connected to the isolation and channel switching module to transmit the conditioned stable excitation signal to this module. The excitation injection and power conditioning module integrates closed-loop dynamic current stabilization control technology to generate multi-frequency AC excitation or composite excitation signals. Subsequently, the excitation signal is converted from voltage to current and the phase calibration and amplitude shaping are performed. Finally, the excitation signal is amplified to a suitable size through power amplification. Under the action of closed-loop dynamic current stabilization control, the excitation signal is injected into the battery under test to achieve a stable excitation output with controllable amplitude, frequency and waveform.

[0011] The signal acquisition and front-end conditioning module is electrically connected to the isolation and channel switching module at one end, acquiring the voltage and current signals of the battery pack under test transmitted by the module, and performing buffering, instrument amplification, and common-mode suppression on the battery voltage and current signals; the other end is electrically connected to the digital control and signal processing module, transmitting the pre-processed signal, and eliminating the DC bias component under the action of DC bias dynamic zero adjustment, realizing high-precision acquisition of weak AC response signals;

[0012] The isolation and channel switching module is connected to the battery pack under test at one end and electrically connected to the excitation injection and power conditioning module and the signal acquisition and front-end conditioning module at the other end. The isolation and channel switching module is used to selectively connect the excitation channel and the acquisition channel among multiple battery cells and provide electrical isolation to avoid crosstalk between channels and high common-mode interference.

[0013] The digital control and signal processing module is electrically connected to the isolation and channel switching module, the excitation injection and power conditioning module, and the signal acquisition and front-end conditioning module, respectively. The digital control and signal processing module is used to control excitation generation and injection, synchronously acquire signals and perform frequency domain analysis, calculate and output the EIS results of the battery cells.

[0014] Furthermore, the closed-loop dynamic current stabilization control technology monitors the excitation waveform in real time, dynamically adjusts the digital-to-analog converter (DAC) output based on sampling feedback, and combines phase calibration and power amplification loops with the closed-loop dynamic current stabilization control module to achieve closed-loop adaptive control of the excitation amplitude and waveform, ensuring that the excitation current remains stable under changes in external load or fluctuations in battery pack operating status. The excitation injection and power conditioning module sequentially includes a DAC signal generation module, a V / I conversion module, a phase calibration module, a power amplification module, and a closed-loop dynamic current stabilization control module. The DAC signal generation module is used to generate single-frequency, composite-frequency, swept-frequency, or other wide-frequency domain excitation signals containing AC forms to meet the requirements of... Wideband EIS measurement requirements; a V / I conversion module is used to convert the calibrated excitation voltage signal into a current signal; a phase calibration module is used to correct the phase deviation between the voltage signal and the current signal; a power amplification module is used to boost the power of the generated current excitation signal to adapt to the battery pack EIS testing requirements; a closed-loop dynamic current stabilization control module is used to monitor and stabilize the excitation current in real time; the closed-loop dynamic current stabilization control module samples the excitation waveform injected into the battery pack in real time, generates a feedback signal and transmits it to the excitation injection and power conditioning module, dynamically adjusts the output parameters of the DAC signal generation module, suppresses the drift of the excitation current with load or operating conditions, and ensures that each cell obtains a stable and accurate excitation signal.

[0015] Furthermore, the signal acquisition and front-end conditioning module includes a buffer amplification module, an instrumentation amplification module, a common-mode rejection module, a DC bias dynamic zeroing module, and an ADC acquisition module. Through the buffer amplification module, instrumentation amplification module, and common-mode rejection structure, combined with DC bias dynamic zeroing technology, high-precision acquisition of weak AC response signals is achieved, reducing the impact of operational amplifier drift, bias error, and ADC quantization noise on the measurement results. Specifically, the buffer amplification module performs impedance matching and preliminary amplification on the raw voltage and current signals output from individual battery cells, improving signal driving capability; the instrumentation amplification module performs high-gain, low-noise amplification of the signal, increasing the amplitude of the weak AC response signal; the amplification factor can be adjusted programmatically through the digital control and signal processing module; the common-mode rejection module suppresses system common-mode interference and crosstalk, improving the signal-to-noise ratio; the DC bias dynamic zeroing module detects and eliminates the DC bias component caused by the battery's DC operating point and operational amplifier drift in real time, highlighting the weak AC impedance response signal; and the ADC acquisition module converts the conditioned analog signal into a digital signal and transmits it to the digital control and signal processing module.

[0016] Furthermore, the isolation and channel switching module includes a switch matrix and an isolation matrix. The switch matrix is ​​used to select the corresponding channel of the battery cell under test according to the control command, realizing the channel switching and selection of the excitation path and the acquisition path. The isolation matrix is ​​used to achieve electrical isolation between each channel and between the excitation path and the acquisition path, suppressing common-mode interference and inter-channel crosstalk, supporting the collaborative or parallel testing of multiple battery cells, realizing system-level expansion, and avoiding inter-channel crosstalk and high common-mode interference.

[0017] Furthermore, the digital control and signal processing module uses an MCU as the core control unit to coordinate the collaborative work of the entire architecture, and receives digital signals transmitted by the signal acquisition and front-end conditioning module; the digital control and signal processing module is used to perform frequency domain analysis and impedance calculation of the acquired signals, generate EIS test results, and output data to the terminal control platform to complete the transmission of test results and the reception of control commands.

[0018] Furthermore, the specific implementation of the DC bias dynamic zeroing technology is as follows: based on the instrument amplification module and buffer amplification module of the signal acquisition and front-end conditioning module, the DC bias component in the voltage and current measurement channels is acquired in real time, and a compensation signal with the same amplitude and opposite direction as the DC bias component is generated to cancel the influence of DC bias, so that the weak AC response signal can be adapted to the acquisition range of the low-precision high-speed ADC in the analog-to-digital conversion acquisition module.

[0019] Furthermore, the closed-loop dynamic current stabilization control technology monitors the excitation waveform in real time, dynamically adjusts the DAC output based on sampling feedback, and combines power amplification and phase calibration loops to achieve closed-loop adaptive control of the excitation amplitude and waveform, so that the excitation current remains stable under changes in external load or fluctuations in the battery pack's operating status.

[0020] Furthermore, the excitation injection and power conditioning module can generate single-frequency, composite-frequency, swept-frequency, or other excitation signals containing AC forms to meet the wideband EIS measurement requirements.

[0021] Furthermore, the isolation and channel switching module uses a multi-channel analog switch to construct a switching matrix for channel switching, supporting channel selection for multiple battery cells. Each test channel is independently powered and not grounded, effectively suppressing grounding interference of series battery packs and supporting system-level channel expansion.

[0022] Furthermore, when applied to battery pack testing, a four-wire detection method (Kelvin connection method) is adopted. Two test wires are used to inject excitation signals, and the other two test wires are used to acquire response signals. The excitation channel and response channel are transmitted separately to reduce the influence of wire resistance and contact resistance on the measurement results.

[0023] Furthermore, the four functional modules of this architecture strictly implement dual isolation between signal channels and power channels, and the modules are electrically connected through shielded cables to ensure high-precision signal transmission and system anti-interference capability. Among them, the isolation and channel switching module integrates a switch matrix and an isolation matrix to realize the switching and selection of multiple individual channels of the battery pack under test and electrical isolation.

[0024] Furthermore, the DC bias dynamic zeroing technology is based on the instrument amplification and buffer amplification structure, which estimates and eliminates the DC bias component in the voltage and current measurement channels in real time.

[0025] Furthermore, the isolation and channel switching module ensures that the core acquisition units of each test channel are independent and do not share a common ground, thus avoiding common ground interference caused by the battery series structure.

[0026] Furthermore, the digital control and signal processing module enables parallel testing or rapid polling testing of multiple battery cells by controlling the channel selection logic of the isolation and channel switching module.

[0027] Furthermore, the digital control and signal processing module, excitation injection and power conditioning module, signal acquisition and front-end conditioning module, and isolation and channel switching module strictly implement physical and electrical isolation between signal channels and power channels at the structural design and electrical connection levels to avoid mutual interference between different functional modules. The system integrates a power matrix, switch matrix, power matrix, and isolation matrix. Depending on the application scenario, these matrices will be integrated into different modules. Among them, the switch matrix and isolation matrix belong to the isolation and channel switching module. The switch matrix is ​​used to realize flexible configuration and switching of multiple signal channels, and the isolation matrix is ​​used to provide electrical isolation between signal channels, power channels, and control channels, thereby ensuring the stability, safety, and reliability of the system under multi-channel, high-precision measurement and complex working conditions. The power matrix is ​​used to realize the unified allocation and management of multiple power supplies, and the power matrix is ​​used to complete the power matching and output conditioning of excitation signals.

[0028] This invention proposes an EIS multi-channel parallel sampling device based on the above architecture, which integrates the digital control and signal processing module, excitation injection and power conditioning module, signal acquisition and front-end conditioning module, and isolation and channel switching module. Each module is deployed according to the connection relationship defined by the architecture, and is used for online, wide-frequency domain, high-precision EIS testing of multiple cells in a battery pack. It can be directly integrated into existing battery management systems (BMS) or energy storage systems.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. Supports online EIS testing: Without interrupting battery pack operation or disconnecting electrical connections, stable excitation injection is achieved under complex operating conditions through closed-loop dynamic current stabilization control technology. EIS testing can be carried out in real time while the battery pack is running, meeting online monitoring requirements.

[0031] 2. High-precision acquisition of weak signals: Based on DC bias dynamic zeroing technology, combined with buffer amplification, instrument amplification and common-mode rejection processing, it can realize high-precision acquisition of microvolt-level impedance response signals, significantly improve the measurement accuracy of impedance amplitude and phase, and especially improve the measurement effect in high-frequency and low-impedance scenarios.

[0032] 3. Parallel testing capability of multiple battery cells: Through the modular design of isolation and channel switching modules, parallel or rapid polling testing of multiple battery cells can be achieved, which significantly improves testing efficiency and is suitable for large-scale battery pack application scenarios.

[0033] 4. Excellent system scalability and integration: DC bias dynamic zeroing technology reduces the accuracy requirements of ADC, enabling high-precision acquisition using low-cost, high-speed ADCs, significantly reducing hardware costs; the system structure adopts a modular design, which is low-cost and can flexibly expand the number of test channels according to the size of the battery pack, and is easy to integrate into existing battery management systems (BMS) or energy storage systems, meeting the actual needs of electric vehicles and large-scale energy storage systems for battery status monitoring, and has strong engineering deployment capabilities. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a wideband EIS excitation-acquisition fusion architecture for battery packs.

[0035] Figure 2 This is an EIS multi-channel parallel sampling device built on a wide-frequency domain EIS excitation-acquisition fusion architecture for battery packs.

[0036] Figure 3 The data are the raw EIS data, where (a) is the current excitation and voltage response obtained from the EIS test, and (b) is the EIS data calculated from the EIS test. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that these embodiments are only for explaining the present invention and are not intended to limit the scope of protection of the present invention. Conventional technical means not described in detail are all common knowledge to those skilled in the art; all hardware selections are merely specific examples adapted to this solution and can be replaced according to actual engineering needs. The replaced technical solutions still fall within the scope of protection of the present invention.

[0038] This invention provides a detailed description of the wideband EIS excitation-acquisition fusion architecture, multi-channel parallel sampling device, and testing process and results for battery packs. This embodiment is adapted to the online EIS monitoring scenario of 13-cell energy storage battery packs (single cell specifications: 3.2V, 314Ah, internal resistance ~200μΩ) in energy storage systems, realizing multi-cell parallel online wideband EIS testing, taking into account the requirements of testing accuracy, stability and low cost.

[0039] Example 1: Wideband EIS Excitation-Acquisition Fusion Architecture for Battery Packs

[0040] This embodiment applies the wideband EIS excitation-acquisition fusion architecture of the present invention to the online testing scenario of battery packs in an energy storage system, demonstrating the specific implementation of the overall system architecture and core technologies.

[0041] 1. Battery pack structure and testing methods

[0042] The batteries inside an energy storage system are usually in the form of battery packs and are encapsulated as a standard battery pack structure. The individual cells in the battery pack are mostly connected in series. Therefore, when conducting EIS testing, it is necessary to effectively suppress the influence of wire resistance, contact resistance and grounding interference on the measurement results.

[0043] In this embodiment, two test leads are drawn from the positive and negative terminals of each battery cell, and a four-wire detection method (Kelvin connection method) is used for battery EIS measurement: two test leads are used to inject excitation signals; the other two test leads are used to acquire response signals; the excitation channel and response channel are transmitted separately, which effectively reduces the influence of wire resistance, contact resistance, signal crosstalk and external interference on the measurement results, ensures high-fidelity transmission of excitation and response signals, and improves impedance measurement accuracy, especially in high-frequency and low-impedance measurement scenarios.

[0044] 2. System Integration Method

[0045] The wideband EIS excitation-acquisition fusion architecture for battery packs in this embodiment integrates various functional modules in an orderly manner, including: an excitation injection and power conditioning module; a signal acquisition and front-end conditioning module; an isolation and channel switching module; and a digital control and signal processing module. The core is designed to address the technical pain points of existing EIS test architectures, such as low efficiency in multi-cell testing, unstable excitation signals, weak resolution of weak impedance signals, and poor anti-interference capabilities. It is suitable for engineering online monitoring scenarios such as energy storage systems and electric vehicles. The overall architecture is as follows: Figure 1 As shown, the modules are logically laid out and tightly connected. The specific integration method is as follows:

[0046] The isolation and channel switching module is directly connected to the battery pack under test, serving as the core for channel transfer and isolation. The digital control and signal processing module is electrically connected to the other three functional modules, leading the collaborative work of the entire system. The excitation injection and power conditioning module and the signal acquisition and front-end conditioning module are both electrically connected to the isolation and channel switching module, respectively responsible for the generation and injection of excitation signals and the acquisition and preprocessing of response signals, ensuring the reliability of the test link closed loop.

[0047] The isolation and channel switching module serves as the core of the entire architecture for channel relay and isolation. It integrates a switch matrix and an isolation matrix. One end is directly connected to the 13-cell battery pack under test (this number can be adjusted by modifying the switching module), and the other end is electrically connected to the excitation injection and power conditioning module and the signal acquisition and front-end conditioning module, respectively. This enables selective switching and reliable electrical isolation of excitation and acquisition channels for multiple individual cells, supporting parallel or polling testing of multiple cells. The switch matrix is ​​used to select the corresponding channel for the individual cell under test according to the instructions of the digital control and signal processing module, realizing the separation and switching of the excitation path and the acquisition path. The isolation matrix is ​​used to achieve electrical isolation between test channels and between the excitation path and the acquisition path, suppressing common-mode voltage and crosstalk between channels, ensuring the purity and reliability of the test signal, and adapting to the high common-mode voltage scenario caused by series connection of battery packs.

[0048] The excitation injection and power conditioning module, serving as the core of excitation signal generation, conditioning, and output, sequentially includes a DAC signal generation module, a V / I conversion module, a phase calibration module, a power amplification module, and a closed-loop dynamic current stabilization control module. One end is electrically connected to the digital control and signal processing module to receive its control commands, while the other end is electrically connected to the isolation and channel switching module, transmitting the conditioned and stable excitation signal to this module, which is then injected into the target cell of the battery pack under test, achieving a wide-frequency, highly stable excitation signal output. The DAC signal generation module, with a DAC as its core, generates wide-frequency excitation signals such as single-frequency, composite-frequency, and swept-frequency signals. The power amplification module increases the excitation signal power to meet the battery pack testing requirements. The V / I conversion module converts voltage excitation into current excitation to meet the low internal resistance testing of battery packs. The phase calibration module corrects the phase deviation of the excitation signal to ensure phase accuracy. The closed-loop dynamic current stabilization control module stabilizes the excitation current in real time, suppressing signal drift.

[0049] The signal acquisition and front-end conditioning module, serving as the core of the response signal acquisition-preprocessing-conversion process, sequentially includes a buffer amplification module, an instrumentation amplification module, a common-mode rejection module, a DC bias dynamic zeroing module, and an ADC acquisition module. One end is electrically connected to the isolation and channel switching module, acquiring the voltage response signal and current excitation signal of the battery pack under test transmitted through this module. The other end is electrically connected to the digital control and signal processing module, transmitting the preprocessed digital signal to this module, achieving high-precision acquisition of weak AC response signals and adapting to the acquisition link of a low-cost, high-speed ADC. The buffer amplification module performs impedance matching and initial signal amplification; the instrumentation amplification module amplifies the weak AC signal with high gain and low noise; the common-mode rejection module filters interference signals and improves the signal-to-noise ratio; the DC bias dynamic zeroing module cancels out the DC bias component, highlighting the weak AC signal; and the ADC acquisition module converts the analog signal into a digital signal and transmits it to the digital control and signal processing module.

[0050] The digital control and signal processing module, serving as the core control and data processing hub of the entire architecture, employs an MCU as its core control unit. It includes a signal processing unit, a control command output unit, a data interaction unit, and a frequency domain analysis unit. These are electrically connected to the isolation and channel switching module, the excitation injection and power conditioning module, and the signal acquisition and front-end conditioning module, respectively. The module coordinates the entire system's collaborative operation, performing signal processing, impedance calculation, command issuance, and data interaction functions, supporting system engineering integration. The control command output unit issues control commands to each module. The signal processing unit filters, reduces noise, and synchronizes the acquired signals. The frequency domain analysis unit performs frequency domain analysis using the FFT algorithm, calculates battery impedance parameters, and generates EIS test results. The data interaction unit enables data interaction with the BMS and the host computer, completing test result transmission and command reception.

[0051] The core of the device integrates four major functional modules: excitation injection and power conditioning module, signal acquisition and front-end conditioning module, isolation and channel switching module, and digital control and signal processing module. Each module adopts a standardized and modular design, which facilitates assembly, debugging, and subsequent maintenance and upgrades. The device also integrates core functional units such as switching matrix, power matrix, and isolation matrix. Among them, the switching matrix and isolation matrix are the core components of the isolation and channel switching module. The matrices work together to not only support the device's multi-channel switching, electrical isolation, and stable excitation output functions, but also optimize the power supply to achieve independent power supply isolation for each module and each channel, ensuring power supply stability and anti-interference capability.

[0052] Each module is connected via shielded cabling, and the signal and power channels are strictly isolated to ensure high-precision signal transmission and anti-interference capabilities. The core acquisition units of each test channel are independent and do not share a common ground within the system, effectively avoiding grounding interference caused by the battery series structure and improving data consistency and reliability during multi-channel parallel testing. In addition, the excitation closed-loop current stabilization control and the acquisition DC bias dynamic zeroing technology work together to achieve parallel EIS measurement of multiple individual cells, while ensuring high-precision measurement over a wide frequency range and improving the ability to resolve weak impedance signals. This device supports multi-channel parallel testing and system expansion, facilitating engineering deployment and online monitoring of energy storage systems. It also has advantages such as high impedance acquisition accuracy, strong system scalability, and multi-cell parallel testing, providing a means for real-time and online monitoring of multi-cell parallel EIS in battery packs and providing reliable technical support for battery online status monitoring and health assessment.

[0053] Furthermore, the device fully leverages the synergistic advantages of its core technologies, combining the closed-loop dynamic current stabilization control technology of the excitation injection and power conditioning module with the DC bias dynamic zeroing technology of the signal acquisition and front-end conditioning module. The two technologies work together to achieve synergistic effects: the closed-loop dynamic current stabilization control technology ensures that the excitation signal injected into each individual cell is stable and drift-free, while the DC bias dynamic zeroing technology effectively counteracts the influence of the DC bias component, highlighting the weak AC impedance response signal. Together, they enable parallel EIS measurement of multiple individual cells, while ensuring high-precision measurement requirements over a wide frequency range, significantly improving the resolution capability of weak impedance signals, and accurately capturing micro-ohm impedance changes in individual cells.

[0054] This embodiment presents a wideband EIS excitation-acquisition fusion architecture for battery packs. Through the collaborative work of four modules, it possesses the following core advantages: First, it achieves dual isolation between the signal channel and the power channel, providing strong anti-interference capabilities and adapting to complex electromagnetic environments; second, it employs closed-loop dynamic current stabilization and DC bias dynamic zeroing technology to ensure high-precision measurement over a wideband frequency range and improve the ability to resolve weak impedance signals; third, it supports parallel testing of multiple individual cells, significantly improving testing efficiency; and fourth, it uses a low-cost, high-speed ADC, balancing testing accuracy and hardware cost, facilitating engineering deployment and expansion.

[0055] Example 2: EIS Multi-channel Parallel Sampling Device

[0056] like Figure 2 As shown, this embodiment provides an EIS multi-channel parallel sampling device based on the fusion architecture described in Embodiment 1. This device standardizes and modularizes the digital control and signal processing module, excitation injection and power conditioning module, signal acquisition and front-end conditioning module, and isolation and channel switching module in Embodiment 1. By optimizing the internal layout design and connection method, it realizes parallel sampling of multi-channel EIS signals. It is suitable for the online monitoring needs of multiple individual cells in energy storage system battery packs and has good engineering adaptability, maintainability, and system expansion capabilities.

[0057] The device mainly includes a power supply (such as...) Figure 2 The diagram shows key components such as battery-powered EIS, EIS detection matrix, isolation and channel switching matrix, and EIS test operation screen. The EIS detection matrix integrates the excitation injection and power conditioning module, signal acquisition and front-end conditioning module, and digital control and signal processing module under the fusion architecture. It can independently complete the EIS excitation, signal acquisition, and data processing of a single battery cell, and realize the direct measurement of battery EIS.

[0058] The isolation and channel switching matrix includes functional units such as a power matrix, a switching matrix, a power matrix, and an isolation matrix. It is used to realize power supply management, channel switching, power conditioning, and electrical isolation between different battery cells and the EIS detection matrix. It is an expandable EIS isolation and channel switching module. The functional units are designed with strict signal channel and power channel isolation to ensure high-precision signal transmission and good anti-interference capability. The core acquisition units of each test channel (i.e., the EIS detection matrix part) are independent and do not share a ground within the system. This effectively avoids grounding interference caused by battery series structure and safety hazards caused by high voltage isolation, thereby improving data consistency and system reliability under multi-channel parallel testing conditions.

[0059] This device supports multi-channel parallel testing and system scaling, enabling parallel EIS measurements of multiple individual cells within a battery pack. While ensuring wide-frequency and high-precision impedance measurement capabilities, it improves the acquisition quality of weak impedance signals, making it suitable for engineering deployment and online monitoring applications in energy storage systems. The device boasts advantages such as high impedance acquisition accuracy, strong system scalability, and robust multi-cell parallel testing capabilities, providing effective support for real-time, online EIS monitoring of multiple individual cells in battery packs and offering a reliable technical foundation for online battery status monitoring and health assessment.

[0060] It should be noted that the number of EIS detection matrices can be flexibly configured according to application requirements; for example, such as Figure 2 As shown, the EIS detection matrix is ​​set to 8 blocks. In application scenarios with a large number of batteries and high requirements for device size and portability, the number of EIS detection matrices can be reduced to 1 block, and the isolation and channel switching matrix can be configured to correspond to the number of individual battery cells, thereby realizing individual EIS testing of each individual battery cell in the battery pack. Correspondingly, in scenarios with high requirements for testing efficiency, the number of EIS detection matrices can be increased and matched with the isolation and channel switching matrix to realize rapid parallel EIS testing of multiple individual battery cells in the battery pack.

[0061] Example 3: Testing Process and Results

[0062] To verify the technical effectiveness of the fusion architecture described in Example 1 and the multi-channel parallel sampling device described in Example 2, the device constructed in Example 2 was used to conduct electrochemical impedance spectroscopy (EIS) tests on the cells within the battery pack. The test results are as follows: Figure 3 As shown. The battery type under test is a 314Ah high-capacity lithium-ion battery, which is widely used in current energy storage power stations.

[0063] From the perspective of current excitation and voltage response, under AC signal excitation conditions, the excitation current amplitude of each test channel is stable and the phase consistency is good. The voltage response signal noise level is low, and no obvious crosstalk or inter-channel coupling phenomenon is observed. This indicates that the fusion architecture and multi-channel parallel sampling device can achieve stable and reliable excitation injection and signal acquisition under multi-unit parallel testing conditions.

[0064] Analysis of EIS characteristics revealed clear, continuous, and physically meaningful impedance features in the low-frequency, mid-frequency, and high-frequency regions: in the high-frequency region, the real intercept of the impedance spectrum curve was clear, stably reflecting the ohmic internal resistance characteristics of the battery; in the mid-frequency region, the impedance spectrum exhibited a typical charge transfer impedance characteristic arc, with a complete arc shape and good repeatability, indicating that the system has high phase and amplitude measurement accuracy; in the low-frequency region, the impedance spectrum showed obvious diffusion correlation characteristics, effectively reflecting the internal electrochemical processes and mass transfer behavior of the battery; no significant shift or distortion was observed in the test results, verifying the stability and reliability of the device under EIS sampling conditions.

[0065] In summary, the test results show that the wideband EIS excitation-acquisition fusion architecture proposed in Embodiment 1 of this invention is reasonable, and the EIS multi-channel parallel sampling device described in Embodiment 2 is stable and reliable in operation, with each functional module working well in coordination. It can realize parallel, online, wideband EIS testing of multiple individual cells in the battery pack, and has the advantages of high stability, high measurement accuracy, low system cost and high testing efficiency. It can provide effective technical support for online status monitoring and health assessment of batteries in energy storage systems.

[0066] This device boasts excellent scalability and engineering adaptability, supporting multi-channel parallel testing. The number of channels can be cascaded to meet the testing needs of energy storage systems of different scales, based on the actual number of battery cells under test. Its modular integrated design and standardized interfaces facilitate integration and deployment with energy storage systems, adapting to online monitoring scenarios. In summary, this device possesses core advantages such as high impedance acquisition accuracy, strong system scalability, high efficiency in multi-cell parallel testing, and excellent anti-interference capabilities. It provides a reliable means for real-time, online EIS monitoring of multiple battery cells in parallel, accurately acquiring the impedance parameters of each cell. This provides solid technical support for online battery status monitoring, health assessment, and fault early warning, making it suitable for various engineering applications such as energy storage systems and electric vehicles.

[0067] The hardware selection and parameter settings in the above embodiments are only specific examples. According to actual engineering needs (number of battery packs, test accuracy, excitation frequency range), the corresponding hardware devices can be replaced and the parameter settings can be adjusted. As long as the four functional modules, core connection relationships and core technologies of the present invention are used, the replaced technical solutions are within the protection scope of the present invention.

Claims

1. A wideband EIS excitation-acquisition fusion architecture for battery packs, characterized in that, Based on closed-loop dynamic current stabilization control technology and DC bias dynamic zeroing technology, it is used to realize parallel online wide-frequency domain electrochemical impedance spectroscopy (EIS) testing of multiple cells in the battery pack. It includes an excitation injection and power conditioning module, a signal acquisition and front-end conditioning module, an isolation and channel switching module, and a digital control and signal processing module. One end of the excitation injection and power conditioning module is electrically connected to the digital control and signal processing module, and the other end is electrically connected to the isolation and channel switching module. This module is used to generate a wide frequency domain AC excitation signal, which is then power conditioned and transmitted to the isolation and channel switching module before being injected into the battery pack under test. The excitation injection and power conditioning module integrates closed-loop dynamic current stabilization control technology to achieve stable output of the excitation signal amplitude, frequency and waveform. The signal acquisition and front-end conditioning module is electrically connected to the isolation and channel switching module at one end and to the digital control and signal processing module at the other end. This module is used to acquire the voltage and current response signals of the battery pack under test, and to perform preprocessing of the acquired signals and transmission of the preprocessed signals. The signal acquisition and front-end conditioning module integrates DC bias dynamic zero adjustment technology to eliminate DC bias components and achieve high-precision acquisition of weak AC response signals. The isolation and channel switching module is connected to the battery pack under test at one end and electrically connected to the excitation injection and power conditioning module and the signal acquisition and front-end conditioning module at the other end, respectively. It is used to achieve selective switching of the excitation channel and acquisition channel of multiple battery cells and to provide electrical isolation to suppress crosstalk and common-mode interference between channels. The digital control and signal processing module is electrically connected to the excitation injection and power conditioning module, the signal acquisition and front-end conditioning module, and the isolation and channel switching module, respectively. It is used to coordinate and control the collaborative work of each module, perform frequency domain analysis and impedance calculation on the acquired signal, and generate and output EIS test results.

2. The wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, The closed-loop dynamic current stabilization control technology monitors the excitation waveform in real time, dynamically adjusts the DAC output based on sampling feedback, and combines phase calibration and power amplification loops with the closed-loop dynamic current stabilization control module to achieve closed-loop adaptive control of the excitation amplitude and waveform, ensuring that the excitation current remains stable under changes in external load or fluctuations in battery pack operating status. The excitation injection and power conditioning module sequentially includes a DAC signal generation module, a V / I conversion module, a phase calibration module, a power amplification module, and a closed-loop dynamic current stabilization control module. The DAC signal generation module generates single-frequency, composite-frequency, swept-frequency, or other wide-frequency excitation signals containing AC forms to meet the wide-frequency EIS measurement requirements. The closed-loop dynamic current stabilization control module samples the excitation waveform injected into the battery pack in real time, generates a feedback signal, and transmits it to the excitation injection and power conditioning module, dynamically adjusting the output parameters of the DAC signal generation module to suppress excitation current drift.

3. The wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, The signal acquisition and front-end conditioning module, through buffer amplification, instrumentation amplification, and common-mode rejection modules, combined with DC bias dynamic zeroing technology, achieves high-precision acquisition of weak AC response signals and reduces the impact of operational amplifier drift, bias error, and ADC quantization noise on measurement results. The signal acquisition and front-end conditioning module sequentially includes a buffer amplification module, a DC bias dynamic zeroing module, an instrumentation amplification module, a common-mode rejection module, and an ADC acquisition module. The buffer amplification module is used for impedance matching and initial signal amplification; the instrumentation amplification module is used for high-gain, low-noise amplification of weak AC response signals; and the DC bias dynamic zeroing module is used to detect and eliminate DC bias components caused by the battery's DC operating point and operational amplifier drift in real time, generating a compensation signal to counteract the DC bias effect.

4. The wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, The isolation and channel switching module supports collaborative or parallel testing of multiple individual battery cells, enabling system-level expansion and avoiding crosstalk and high common-mode interference between channels. The isolation and channel switching module includes a switch matrix and an isolation matrix. The switch matrix is ​​used to select the excitation channel and acquisition channel of the battery cell under test according to the instructions of the digital control and signal processing module. The isolation matrix is ​​used to achieve electrical isolation between each test channel and between the excitation path and the acquisition path. Each test channel is independently powered and does not share a common ground.

5. A wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 4, characterized in that, The switch matrix is ​​constructed using multi-channel analog switch chips, which supports the selection of multiple battery cell channels and can expand the number of channels through cascading to achieve collaborative or parallel testing of multiple battery cells and system-level expansion.

6. The wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, The digital control and signal processing module performs frequency domain analysis, impedance calculation, and result output of the acquired signals. It also interacts with the battery management system via software or hardware interfaces to enable engineering applications. The module uses a microcontroller unit as its core control unit, comprising a signal processing unit, a frequency domain analysis unit, and a data interaction unit. The frequency domain analysis unit performs frequency domain analysis on the acquired signals using a fast Fourier transform algorithm to calculate the impedance parameters of individual battery cells. The data interaction unit interacts with the battery management system and the host computer, transmitting test results and receiving control commands.

7. A wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, The digital control and signal processing module, excitation injection and power conditioning module, signal acquisition and front-end conditioning module, and isolation and channel switching module achieve dual isolation at the signal channel level and the power channel level. The modules are connected by shielded cables and internally integrate a power matrix, a switching matrix, a power matrix, and an isolation matrix. The power matrix provides independent power supply allocation for each module and test channel.

8. A wideband EIS excitation-acquisition fusion architecture for battery packs according to claim 1, characterized in that, When applied to battery pack testing, a separate detection connection method is adopted, which transmits signals through independent excitation and acquisition paths to reduce the impact of various interference factors on the measurement results during transmission.

9. An EIS multi-channel parallel sampling device, characterized in that, The system integrates the wideband EIS excitation-acquisition fusion architecture for battery packs as described in any one of claims 1-8. Each module is modularly deployed and packaged into a single unit. It is equipped with various interfaces adapted to engineering applications and can be integrated into various battery management and energy storage related systems to achieve online, wideband, and high-precision EIS testing of multiple individual cells in the battery pack.

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