Lithium battery formation and capacity grading test health monitoring and performance diagnosis method and system

Abstract

The invention relates to the technical field of lithium batteries, in particular to a lithium battery formation and capacity grading test health monitoring and performance diagnosis method and system. Comprising the following steps: acquiring voltage data, and identifying a target single cell according to the voltage data; a bypass current channel is gradually established for the target single battery cell, so that the bypass current is gradually increased from zero or an initial value according to the change speed of the bypass current; acquiring current change data of the bypass current channel in real time during the establishment period of the bypass current channel, and adjusting the establishment slope and / or the segmented switching time sequence of the bypass current according to the current change data; and when the bypass equalization operation is finished, gradually reducing the bypass current according to the corrected bypass current change speed until the bypass current channel is removed. The problems that in the lithium battery formation and capacity grading test process in the prior art, potential accumulative damage is caused by bypass equalization operation, and transient influences are difficult to accurately capture and evaluate by existing test equipment are solved.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and more specifically, to a method and system for lithium battery formation, capacity testing, health monitoring, and performance diagnosis. Background Technology

[0002] In the production and manufacturing of power batteries for new energy vehicles, the formation and capacity testing process, which involves activating electrode materials through multiple charge-discharge cycles, forming a stable solid electrolyte interphase (SEI) film, and measuring the actual capacity, is a crucial step in ensuring battery quality and performance. As market demands for battery life and consistency increase, and production lines expand, formation and capacity testing often involves long-term, high-intensity continuous operation. This process places even higher demands on cell consistency management in battery packs composed of multiple individual cells connected in series.

[0003] In existing tests, when a single battery cell reaches its voltage limit first during charging, the system typically diverts current by quickly closing a bypass equalization switch to protect that cell and allow other cells to continue charging. However, the rapid switching action of the bypass equalization switch causes abrupt changes in the current path within microseconds to milliseconds. Due to parasitic inductance in the battery pack connecting wires, busbars, and test circuitry, this rapid current switching can induce transient voltage spikes or drops in the series system, which propagate along the battery string and affect other cells that are not bypassed.

[0004] The problem is that conventional testing systems typically have low data acquisition frequencies (e.g., hundreds of milliseconds or seconds), sufficient to record slow changes in steady-state charging and discharging, but struggling to capture transient spikes at the microsecond / millisecond level. These spikes are either missed or averaged out as "noise," making them difficult to identify, assess, and trace. Despite their extremely short duration, transient overvoltages can still have a cumulative impact on the electrochemical health of other cells, especially during the SEI film formation stage, causing localized electrolyte decomposition or microscopic changes in the film structure, thereby reducing the density and uniformity of the SEI film and affecting subsequent cycle stability and lifetime consistency.

[0005] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0006] This application discloses a method and system for health monitoring and performance diagnosis of lithium battery formation and capacity testing. It aims to solve the problem that in the existing technology, transient voltage spikes caused by bypass equalization operation during lithium battery formation and capacity testing can cause potential cumulative damage to the electrochemical health of other cells that are not bypassed, and that existing testing equipment is unable to accurately capture and evaluate these transient effects.

[0007] The technical solution of this application is as follows:

[0008] In a first aspect, this application discloses a method for lithium battery formation, capacity testing, health monitoring, and performance diagnosis, the method comprising:

[0009] Obtain the voltage data of each individual cell in the battery pack, and identify the target individual cell that needs to be bypassed and balanced based on the voltage data.

[0010] In response to the identification of the target cell, a bypass balancing operation is performed: a bypass current channel is gradually established for the target cell at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, in order to suppress transient voltage spikes caused by the rapid switching interaction between the parasitic inductance and current of the internal connecting wires and test system circuits of the battery pack.

[0011] During the establishment of the bypass current channel, the current change data of the bypass current channel is acquired in real time, and the establishment slope of the bypass current and / or the segmented switching sequence are adjusted according to the current change data to ensure that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate.

[0012] At the end of the bypass balancing operation, the bypass current is gradually reduced according to the corrected rate of change of the bypass current until the bypass current channel is removed, and the rate of change of the bypass current during the gradual reduction of the bypass current does not exceed the safe threshold of the rate of change of the bypass current.

[0013] Furthermore, the establishment slope of the bypass current and / or the segmented switching sequence are adjusted based on the current change data to ensure that the rate of change of the bypass current does not exceed a preset safe threshold for the rate of change of the bypass current, including:

[0014] Obtain the voltage data of each individual battery cell;

[0015] Generate charging current adjustment instructions for each individual battery cell based on voltage data.

[0016] The charging current applied to the target cell is gradually reduced at a preset rate of change of charging current. During the gradual reduction of the charging current of the target cell, the slope of the bypass current establishment and / or the segmented switching sequence are adjusted in combination with the current change data. This ensures that the rate of change of bypass current meets the safety threshold of bypass current change rate while reducing the instantaneous fluctuations caused by the interaction between the switching edge of the bypass current channel and parasitic inductance, so as to suppress the superimposed fluctuation components of transient voltage spikes.

[0017] Furthermore, the method also includes:

[0018] During the bypass equalization operation, the voltage change rate signal across the power switching element in the bypass current path is acquired, and the deviation data of the switching transient characteristics of the power switching element from the preset characteristics is determined based on the voltage change rate signal.

[0019] Based on the deviation data, the performance drift data of the power switching element is obtained;

[0020] The drive signal parameters of the power switching element are adaptively adjusted based on the deviation data to compensate for the performance drift of the power switching element.

[0021] Based on the deviation data and drive signal parameters, the segmented switching timing of the bypass current channel is corrected;

[0022] Record performance drift data and update adaptive adjustment strategies and / or output maintenance alerts based on the performance drift data.

[0023] Furthermore, real-time current change data of the bypass current channel is acquired, and the establishment slope of the bypass current and / or the segmented switching timing are adjusted according to the current change data, including:

[0024] During the establishment of the bypass current channel, the current of the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain current change data. The transient component of the current change data is extracted to obtain instantaneous current fluctuation data reflecting the instantaneous current fluctuation of the bypass current channel.

[0025] Processing instantaneous current fluctuation data to identify instantaneous current fluctuation information;

[0026] The slope of bypass current establishment is adjusted based on instantaneous current fluctuation information, and / or the segmented switching sequence of bypass current is adjusted.

[0027] Furthermore, the current in the bypass current channel is sampled at a preset high-frequency sampling rate to obtain current change data. Transient component extraction is performed on the current change data to obtain instantaneous current fluctuation data reflecting the instantaneous current fluctuations in the bypass current channel, including:

[0028] The current of the bypass current channel is sampled in parallel using multiple independent sampling channels at a high frequency, and the current change data corresponding to each sampling channel is obtained.

[0029] Transient components are extracted from the current change data corresponding to each sampling channel to obtain the instantaneous current fluctuation data corresponding to each sampling channel.

[0030] Real-time data consistency verification is performed on instantaneous current fluctuation data acquired in parallel from multiple independent sampling channels to identify and remove abnormal data, thereby obtaining verified instantaneous current fluctuation data.

[0031] Adaptive filtering is applied to the verified instantaneous current fluctuation data to suppress noise, resulting in filtered instantaneous current fluctuation data.

[0032] Reference signals are periodically input into multiple sampling channels, and the performance drift of multiple sampling channels is evaluated based on the response of multiple sampling channels to the reference signals, thereby generating calibration parameters;

[0033] The corrected instantaneous current fluctuation data is obtained by correcting the filtered instantaneous current fluctuation data based on the calibration parameters.

[0034] Furthermore, the slope of the bypass current establishment is adjusted based on instantaneous current fluctuation information, and / or the segmented switching sequence of the bypass current is adjusted, including:

[0035] The electrochemical characteristic parameters of each individual cell were obtained, including internal resistance, capacity, and the formation rate of the solid electrolyte interface film.

[0036] Based on the electrochemical characteristic parameters, current fluctuation response thresholds are established for each individual cell. The current fluctuation response thresholds include peak thresholds and duration thresholds. The peak threshold is used to limit the peak value of instantaneous current fluctuations, and the duration threshold is used to limit the duration of instantaneous current fluctuations.

[0037] The process of establishing the bypass current channel is divided into multiple switching segments, and a switching interval and duration are set for each switching segment, thereby forming a segmented switching sequence.

[0038] When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation of the bypass current channel corresponding to any single cell exceeds its corresponding current fluctuation response threshold, the first adjustment is made to the establishment slope and / or segmented switching sequence of the bypass current corresponding to the single cell:

[0039] In response to the peak value of the instantaneous current fluctuation exceeding the peak threshold, the slope of the bypass current establishment is adjusted according to the formation rate of the solid electrolyte interface film. In response to the duration of the instantaneous current fluctuation exceeding the duration threshold, the conduction duration of the power switching element of the bypass current channel is adjusted according to the internal resistance and capacity, and the duration of each switching segment and / or the switching interval time of the segmented switching sequence are adjusted accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls back to the current fluctuation response threshold and the bypass current change rate does not exceed the bypass current change rate safety threshold.

[0040] Furthermore, adjusting the bypass current establishment slope and / or segmented switching timing based on current change data also includes:

[0041] Generate adjustment instructions, which are used to indicate the adjustment of the bypass current establishment slope and / or segmented switching timing, and the adjustment instructions include timestamp information and check code information;

[0042] The adjustment command is sent to the execution terminal of the bypass current channel corresponding to the target individual cell;

[0043] After receiving the adjustment instruction, the execution end verifies the adjustment instruction based on the check code information;

[0044] Upon successful verification, the timeliness of the adjustment instruction is determined based on the timestamp information, and the adjustment instruction is executed or discarded in response to its timeliness.

[0045] The system receives execution status feedback information from the execution end after executing the adjustment command, judges the execution status of the adjustment command based on the execution status feedback information, and resends the adjustment command and / or adjusts the subsequent adjustment strategy in response to the execution status.

[0046] Furthermore, prior to the first adjustment, it also includes:

[0047] Acquire historical operating data for each individual battery cell, including charge / discharge cycle count, cumulative operating time, and temperature change records;

[0048] Based on the current electrochemical characteristic parameters and historical operating data, assess the degree of drift of the electrochemical characteristic parameters of each individual cell, and predict the trend of the sensitivity change of each individual cell to instantaneous current fluctuations within a preset time window.

[0049] Based on the drift degree and sensitivity change trend, dynamically update the current fluctuation response threshold corresponding to each individual cell, and / or correct the initial setting value of the bypass current establishment slope, and / or correct the initial setting value of the conduction duration of the power switching element of the bypass current channel.

[0050] And when the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, a first adjustment is made based on the initial setting value of the corrected setup slope and / or the initial setting value of the corrected conduction duration.

[0051] Furthermore, the initial setting value of the bypass current establishment slope is corrected, including:

[0052] Obtain formation stage information for each individual cell, including the current state of charge of the individual cell and the thickness of the solid electrolyte interface film that has been formed.

[0053] Based on the formation stage information, drift degree and sensitivity change trend, a nonlinear slope adjustment curve that matches the state of the individual cell is selected from the preset set of nonlinear slope adjustment curves.

[0054] Based on the nonlinear slope adjustment curve, the target change law of the bypass current change rate with time during the bypass current channel establishment period is determined, and an adjustment amount is generated to correct the establishment slope of the bypass current.

[0055] The initial setting value of the bypass current establishment slope is corrected based on the adjustment amount.

[0056] Secondly, this application also discloses a lithium battery formation, capacity testing, health monitoring, and performance diagnosis system, comprising:

[0057] The voltage data acquisition module is used to acquire the voltage data of each individual cell in the battery pack and identify the target individual cell that needs to be bypassed and balanced based on the voltage data.

[0058] The bypass channel establishment module is used to perform bypass balancing operation in response to the identification of the target single cell: for the target single cell, a bypass current channel is gradually established at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, in order to suppress transient voltage spikes caused by the rapid switching interaction between the parasitic inductance and current of the internal connecting wires and test system circuits of the battery pack.

[0059] The current data acquisition module is used to acquire the current change data of the bypass current channel in real time during the establishment of the bypass current channel, and adjust the establishment slope of the bypass current and / or the segmented switching sequence according to the current change data, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate.

[0060] The bypass channel cancellation module is used to gradually reduce the bypass current until the bypass current channel is removed at the end of the bypass balancing operation, according to the corrected bypass current change rate, and to ensure that the bypass current change rate during the gradual reduction process does not exceed the bypass current change rate safety threshold.

[0061] Beneficial Effects: The method of this application can precisely control the establishment and removal process of bypass current. Through gradual current change and real-time adjustment mechanism, it significantly reduces the amplitude and duration of transient voltage spikes, thereby effectively avoiding potential cumulative damage to other unbypassed cells. Furthermore, by real-time monitoring and correction of the bypass current change rate, this application overcomes the shortcomings of existing testing equipment in accurately capturing and evaluating transient effects, providing a more refined and safer battery formation and capacity testing solution, which helps improve the long-term health and performance stability of batteries. Attached Figure Description

[0062] Figure 1 This is a flowchart illustrating a lithium battery formation, capacity testing, health monitoring, and performance diagnosis method provided in this application.

[0063] Figure 2 A flowchart of a lithium battery formation, capacity testing, health monitoring, and performance diagnosis system provided in this application.

[0064] In the diagram: 1. Voltage data acquisition module; 2. Bypass channel establishment module; 3. Current data acquisition module; 4. Bypass channel cancellation module. Detailed Implementation

[0065] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0066] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0067] Traditional lithium-ion battery formation and capacity testing methods have significant technical limitations when dealing with the consistency of individual cells within a battery pack, especially when initiating bypass equalization to protect overvoltage cells. Specifically, the rapid switching action of bypass equalization, due to the rapid interaction between the parasitic inductance and current switching of the internal connecting wires and test system circuitry, easily triggers transient voltage spikes. These short-term, high-amplitude voltage fluctuations cause potential, cumulative damage to the electrochemical health of other cells not bypassed. Existing testing equipment often struggles to accurately capture and assess these transient effects, resulting in an inability to effectively suppress these spikes, thus impacting the long-term performance and lifespan of the battery.

[0068] Reference Figure 1 In response, this application proposes a method for lithium battery formation, capacity testing, health monitoring, and performance diagnosis, the method comprising:

[0069] S1000: Acquires voltage data of each individual cell in the battery pack and identifies the target individual cell that needs to be bypassed for equalization based on the voltage data.

[0070] S2000: In response to the identification of the target single cell, a bypass balancing operation is performed: a bypass current channel is gradually established for the target single cell at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, in order to suppress transient voltage spikes caused by the rapid switching interaction between the parasitic inductance and current of the internal connecting wires and test system circuits of the battery pack.

[0071] S3000: During the establishment of the bypass current channel, the current change data of the bypass current channel is acquired in real time, and the establishment slope of the bypass current and / or the segmented switching sequence are adjusted according to the current change data to ensure that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate.

[0072] S4000: At the end of the bypass balancing operation, the bypass current is gradually reduced according to the corrected bypass current change rate until the bypass current channel is released, and the bypass current change rate during the gradual reduction process does not exceed the bypass current change rate safety threshold.

[0073] "Bypass balancing operation" refers to the process of diverting the charging current flowing to a cell when its voltage reaches a preset upper limit by establishing a bypass current channel. This prevents overcharging of the cell and allows other cells in the battery pack to continue charging, thus achieving a balance of charge state among the cells. "Bypass current change rate" refers to the rate at which the bypass current value changes over time during establishment or removal, typically expressed in amperes per second (A / s). "Transient voltage spike" refers to short-duration, high-amplitude voltage fluctuations caused by parasitic inductance in the circuit during rapid current switching (e.g., opening or closing of the bypass current channel). "Bypass current change rate safety threshold" is the maximum allowable value set for the bypass current change rate to ensure the safe and stable operation of the battery system.

[0074] The method proposed in this application first acquires the voltage data of each individual cell within the battery pack. Voltage data can be acquired in various ways, such as: independently measuring each individual cell using a high-precision voltage sensor and transmitting the measurement results to the processing unit via a data acquisition system; or periodically reading the voltage value of each individual cell using the voltage monitoring function built into the battery management system (BMS). Based on the acquired voltage data, the target individual cell requiring bypass equalization is identified; for example, when the voltage of a certain individual cell exceeds a preset overvoltage threshold, that individual cell is identified as the target individual cell.

[0075] In response to the identification of a target individual cell, a bypass balancing operation is performed: for the target individual cell, a bypass current path is gradually established at a preset bypass current change rate, causing the bypass current to gradually increase from zero or an initial value according to the preset bypass current change rate. The establishment of the bypass current path can be achieved in various ways, such as controlling the conduction level of one or more power switching elements (e.g., MOSFETs or IGBTs) to gradually increase the bypass current; or using a multi-stage bypass resistor network, switching resistors stepwise to increase the bypass current in a stepped manner to simulate the effect of gradual increase. This gradual establishment is used to reduce di / dt, thereby suppressing transient voltage spikes.

[0076] During the establishment of the bypass current channel, real-time current change data of the bypass current channel is acquired. This current change data can be obtained through real-time sampling using a high-frequency current sensor, such as a Hall effect current sensor, or by combining a shunt resistor with a high-precision sampling circuit for continuous monitoring of the bypass current. Based on the acquired current change data, the establishment slope of the bypass current and / or the segmented switching sequence are adjusted to ensure that the bypass current change rate does not exceed the safe threshold for the bypass current change rate, thereby correcting the bypass current change rate. For example, when the detected current change rate is too fast, the duty cycle of the drive signal of the power switching element can be reduced to slow down the current rise rate; when the bypass current channel adopts a segmented switching method, the interval time between each switching segment can be extended or the current increment of each segment can be reduced.

[0077] At the end of the bypass balancing operation, the bypass current is gradually reduced according to the corrected rate of change until the bypass current channel is removed. During this gradual reduction, the rate of change of the bypass current is continuously monitored to ensure it does not exceed the safe threshold for the rate of change of the bypass current. This gradual reduction can be achieved in various ways, such as gradually reducing the conduction level of the power switching elements to allow the bypass current to decrease smoothly, or progressively disconnecting the bypass resistors to achieve a step-by-step reduction, thereby avoiding the introduction of new transient voltage spikes when the bypass current channel is removed.

[0078] The overall technical solution of this application addresses the problem of transient voltage spikes caused by bypass equalization operations during traditional lithium battery formation and capacity testing. In conventional solutions, when a single cell reaches its voltage limit, the bypass equalization function quickly activates and shunts the current. Due to the parasitic inductance in the internal connecting wires of the battery pack and the circuitry of the test system, rapid switching generates transient voltage spikes according to the inductance law (V = L * di / dt). Although the spikes are short in duration, their instantaneous amplitude can be high, potentially causing cumulative damage to the electrochemical health of other cells that are not bypassed, such as accelerating the degradation of the solid electrolyte interphase (SEI) membrane, thereby affecting the long-term performance and lifespan of the battery.

[0079] The key point of this application lies in implementing refined control of the bypass current channel establishment and removal process using a "gradual + real-time feedback" approach: Gradual establishment is achieved through a preset bypass current change rate to reduce di / dt; during establishment, current change data is acquired in real time, and the establishment slope of the bypass current and / or segmented switching sequence are dynamically adjusted to ensure that the bypass current change rate is always controlled within the safe threshold of the bypass current change rate; during the removal phase, the bypass current change rate is also gradually reduced and continuously controlled according to the corrected rate. This minimizes the amplitude and probability of transient voltage spikes, reduces the potential cumulative impact on other individual cells in the battery pack (especially during the SEI film formation stage), and improves the stability and reliability of formation and capacity testing.

[0080] Another embodiment of this application further proposes adjusting the establishment slope of the bypass current and / or the segmented switching sequence based on current change data, so that the rate of change of the bypass current does not exceed a preset safe threshold for the rate of change of the bypass current, including:

[0081] S3001: Obtain the voltage data of each individual battery cell;

[0082] S3002: Generates charging current adjustment commands for each individual battery cell based on voltage data;

[0083] S3003: Gradually reduce the charging current applied to the target cell at a preset charging current change rate, and adjust the establishment slope of the bypass current and / or the segmented switching sequence in combination with the current change data during the gradual reduction of the charging current of the target cell, so that the bypass current change rate meets the safety threshold of the bypass current change rate, while reducing the instantaneous fluctuations caused by the interaction between the switching edge of the bypass current channel and the parasitic inductance, so as to suppress the superimposed fluctuation components of transient voltage spikes.

[0084] Specifically, during bypass balancing, the voltage data of each individual cell in the battery pack is first acquired. Based on this voltage data, charging current adjustment commands are generated for each individual cell. These charging current adjustment commands control the charging equipment to apply charging current to specific individual cells, thereby achieving fine-grained management of the charging state of individual cells.

[0085] In practical applications, for target cells that require bypass balancing, the charging current applied to them is gradually reduced at a preset rate of change to smooth the total current change of the target cell and reduce the current surge caused by the intervention of bypass current.

[0086] During the establishment of the bypass current channel, the current change data in the bypass current channel is acquired in real time, and the establishment slope and / or segmented switching sequence of the bypass current are dynamically adjusted in combination with the current change data to ensure that the bypass current change rate does not exceed the preset bypass current change rate safety threshold. At the same time, the dynamic adjustment reduces the instantaneous fluctuations caused by the interaction between the switching edge of the bypass current channel and the parasitic inductance, thereby suppressing the superimposed fluctuation components of transient voltage spikes.

[0087] In some preferred embodiments, the following specific example illustrates the situation:

[0088] Suppose that during the lithium battery formation and capacity testing process, the system detects that the voltage of a single cell is too high, requiring a bypass equalization operation. Before initiating the bypass equalization operation, the system first acquires the real-time voltage data of the target single cell. Based on this voltage data, the control system generates a charging current adjustment command, instructing the charging device to gradually reduce the charging current applied to the target single cell at a rate of, for example, 0.1A per second. Simultaneously, a bypass current channel is established, with the bypass current gradually increasing at a preset initial slope. During the establishment of the bypass current channel, a high-frequency current sensor monitors the current changes in the bypass current channel in real time. If the monitoring data shows unexpected instantaneous fluctuations at the switching edge of the bypass current, such as a slight oscillation at the rising edge of the current, the system immediately combines the current change data to dynamically adjust the establishment slope of the bypass current to make it smoother, or adjust the segmented switching sequence, such as extending the duration of a certain switching segment or adjusting the switching interval, to smooth the current transition. By gradually reducing the charging current and finely adjusting the bypass current, the instantaneous fluctuations caused by the interaction between the switching edge and the parasitic inductance can be effectively absorbed and suppressed, thereby avoiding the superposition of transient voltage spikes and ensuring the stability and safety of the bypass balancing process.

[0089] Another embodiment of this application further proposes that the lithium battery formation, capacity testing, health monitoring, and performance diagnosis method also includes:

[0090] S5000: During bypass equalization operation, acquire the voltage change rate signal across the power switching element in the bypass current path, and determine the deviation data of the switching transient characteristics of the power switching element from the preset characteristics based on the voltage change rate signal.

[0091] S6000: Based on the deviation data, obtain the performance drift data of the power switching element;

[0092] S7000: Adaptively adjusts the drive signal parameters of the power switching element based on the deviation data to compensate for the performance drift of the power switching element;

[0093] S8000: Corrects the segmented switching timing of the bypass current channel based on the deviation data and drive signal parameters;

[0094] S9000: Records performance drift data and updates adaptive adjustment strategies and / or outputs maintenance alerts based on the performance drift data.

[0095] In this context, a power switching element refers to a semiconductor device used to control the on / off state of current in a bypass current path, such as a MOSFET or IGBT. The voltage change rate signal across its terminals typically refers to the rate (dV / dt) change of the drain-source (or collector-emitter) voltage over time during the power switching element's turn-on or turn-off process, directly reflecting the switching speed and transient characteristics of the power switching element. Preset characteristics refer to the switching transient characteristics of the power switching element under ideal or initial calibration conditions. Deviation data refers to the difference between the actual measured voltage change rate signal and the preset characteristics, such as changes in rise or fall times, or variations in overshoot or undershoot amplitude.

[0096] Performance drift data refers to the changes in electrical characteristic parameters (such as on-resistance, threshold voltage, transconductance, etc.) of power switching elements caused by factors such as aging, temperature changes, and long-term operation. These changes are reflected or deduced from the deviation data and directly affect the switching transient characteristics. Drive signal parameters refer to the signal characteristics used to control the on and off states of the power switching elements, such as the amplitude of the gate drive voltage, pulse width, and the slope of the rising and falling edges. Adaptive adjustment refers to dynamically modifying the drive signal parameters based on real-time acquired deviation data to offset or compensate for the performance drift of the power switching elements, restoring their switching transient characteristics to the preset characteristics as much as possible. Segmented switching timing refers to the time sequence in which multiple power switching elements work together to phasedly engage or disengage the current path during the establishment or disengagement of the bypass current channel. Correcting the segmented switching timing ensures that the overall change curve of the bypass current conforms to the preset bypass current change rate requirement even when performance drift exists in the power switching elements. Record performance drift data and update adaptive adjustment strategies to optimize subsequent adjustment algorithms based on historical data, thereby improving adjustment accuracy and efficiency; output maintenance warning information to prompt operators to check or replace power switching components that may be faulty.

[0097] In some preferred embodiments, the following specific example illustrates the situation:

[0098] Assume a MOSFET is used as the power switching element in the bypass current path. During bypass equalization operation, the rate of change of voltage (dV / dt) across the drain-source of the MOSFET is monitored in real time using a high-speed oscilloscope or a dedicated voltage sensor. When the MOSFET is turned on or off, its dV / dt waveform reflects its switching speed. For example, if the rising or falling edge of the MOSFET's dV / dt waveform becomes flatter, it indicates a slower switching speed, which is identified as a deviation of the switching transient characteristics from the preset characteristics. Based on this deviation, the system infers MOSFET performance drift, such as increased gate capacitance or decreased transconductance. To compensate for the drift, the control unit adaptively adjusts the MOSFET's gate drive signal parameters, such as increasing the amplitude of the gate drive voltage or adjusting the width of the drive pulse, to accelerate the switching process. Simultaneously, if the bypass current path uses segmented switching, the system fine-tunes the duration and switching interval of each segment based on the adjusted MOSFET switching transient characteristics to ensure that the overall slope of the bypass current remains within the preset safe threshold for the rate of change of bypass current. The performance drift data and adjustment records are stored for subsequent analysis and optimization of adaptive adjustment strategies. When severe drift is detected, maintenance warnings are issued to operators, prompting them to replace or inspect the relevant power switching components.

[0099] Another embodiment of this application further proposes to acquire the current change data of the bypass current channel in real time, and adjust the establishment slope of the bypass current and / or the segmented switching sequence according to the current change data, including the following steps:

[0100] S3100: During the establishment of the bypass current channel, the current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain current change data. The transient component of the current change data is extracted to obtain instantaneous current fluctuation data reflecting the instantaneous current fluctuation in the bypass current channel.

[0101] S3200: Processes instantaneous current fluctuation data to identify instantaneous current fluctuation information;

[0102] S3300: Adjusts the slope of bypass current establishment based on instantaneous current fluctuation information, and / or adjusts the segmented switching sequence of bypass current.

[0103] Specifically, the current in the bypass current channel is sampled at a preset high-frequency sampling rate. The purpose is to capture the rapid and subtle current changes that may occur during the establishment of the bypass current. These changes are often closely related to transient voltage spikes caused by the interaction between the parasitic inductance in the internal connecting wires of the battery pack and the rapid switching of current. High-frequency sampling ensures accurate reconstruction of the current waveform, providing a detailed data foundation for subsequent analysis.

[0104] Extracting transient components from current change data can be understood as using digital signal processing techniques, such as high-pass filtering, wavelet transform, or differential operations, to remove DC or slowly changing components from the current change data, thereby highlighting and separating the instantaneous, rapidly changing current fluctuation components. These instantaneous current fluctuation data directly reflect the transient response of the bypass current channel during switch switching or changes in current slope, and are a key basis for identifying potential transient voltage spikes.

[0105] In practical applications, processing instantaneous current fluctuation data to identify instantaneous current fluctuation information can specifically include threshold comparison, peak detection, duration analysis, or frequency analysis of the extracted instantaneous current fluctuation data. For example, a peak current fluctuation threshold and a duration threshold can be set. When the peak value or duration of an instantaneous current fluctuation exceeds these thresholds, it is identified as instantaneous current fluctuation information that requires attention. The purpose is to transform the raw fluctuation data into actionable information with clear indicative meaning, so that the system can make decisions accordingly.

[0106] Furthermore, the establishment slope of the bypass current is adjusted based on the identified instantaneous current fluctuation information, and / or the segmented switching sequence of the bypass current is adjusted. For example, when excessive instantaneous current fluctuations are detected, the establishment slope of the bypass current can be reduced to make the current change smoother, thereby reducing the amplitude of transient voltage spikes; or, the segmented switching sequence of the bypass current channel can be adjusted, such as extending the switching interval or adjusting the duration of each switching segment, to avoid rapid switching at sensitive moments, thereby effectively suppressing the generation or superposition of transient voltage spikes.

[0107] This application's solution introduces mechanisms for high-frequency sampling, transient component extraction, and fluctuation information identification, enabling the system to perceive instantaneous current fluctuations generated during the establishment of the bypass current channel in real time and with precision. It is precisely because of the timely acquisition and analysis of these subtle current changes that the system can selectively adjust the bypass current establishment slope and / or segmented switching timing. This refined real-time adjustment capability effectively avoids transient voltage spikes caused by the interaction between rapid current switching and parasitic inductance, thus solving the problem of effectively suppressing transient voltage spikes in traditional solutions. Through precise monitoring and feedback control of instantaneous current fluctuations, the bypass current establishment process is optimized, ensuring that current changes always remain within the preset safe threshold for the bypass current change rate, thereby significantly improving the stability and safety of the equalization operation.

[0108] Another embodiment of this application further proposes sampling the current in the bypass current channel at a preset high-frequency sampling frequency to obtain current change data, and extracting transient components from the current change data to obtain instantaneous current fluctuation data reflecting instantaneous current fluctuations in the bypass current channel, including:

[0109] S3110: The current in the bypass current channel is sampled in parallel at a high frequency through multiple independent sampling channels to obtain the current change data corresponding to each sampling channel.

[0110] S3120: Extract transient components from the current change data corresponding to each sampling channel to obtain the instantaneous current fluctuation data corresponding to each sampling channel.

[0111] S3130: Performs real-time data consistency verification on instantaneous current fluctuation data acquired in parallel from multiple independent sampling channels to identify and remove abnormal data, and obtains verified instantaneous current fluctuation data.

[0112] S3140: Apply adaptive filtering to the verified instantaneous current fluctuation data to suppress noise and obtain filtered instantaneous current fluctuation data.

[0113] S3150: Periodically inputs reference signals to multiple sampling channels, evaluates the performance drift of multiple sampling channels based on the response of multiple sampling channels to the reference signals, and generates calibration parameters;

[0114] S3160: Correct the filtered instantaneous current fluctuation data according to the calibration parameters to obtain the corrected instantaneous current fluctuation data.

[0115] Specifically, parallel sampling of the current in the bypass current channel through multiple independent sampling channels refers to using at least two or more independent current sensors or sampling circuits to synchronously acquire the current signal in the bypass current channel at the same time point or within a very short time interval. Each sampling channel operates independently, acquiring its own current change data. The purpose is to provide data redundancy and cross-validation possibilities, thereby improving the reliability of the raw data acquisition. Transient component extraction of the current change data corresponding to each sampling channel involves using signal processing techniques (such as high-pass filtering, wavelet transform, or differential algorithms) to separate the rapidly changing, non-steady-state current components, i.e., instantaneous current fluctuation data, from the current data acquired by each independent sampling channel. This process aims to ensure that each channel can independently identify the instantaneous change characteristics of the current.

[0116] In practical applications, performing real-time data consistency verification on instantaneous current fluctuation data acquired in parallel from multiple independent sampling channels can be understood as comparing and analyzing instantaneous current fluctuation data from different sampling channels to determine whether there are significant differences or anomalies among them. For example, the mean, median, or standard deviation of the data from each channel can be calculated, and a threshold can be set. When the data from a certain channel deviates from the data from other channels or its statistical characteristics exceed the threshold, it is identified as abnormal data and discarded. The purpose is to eliminate erroneous data caused by single sensor failure, line interference, or transient errors, ensuring that the data processed subsequently has a high degree of reliability.

[0117] Furthermore, applying adaptive filtering to the verified instantaneous current fluctuation data to suppress noise refers to using algorithms that can automatically adjust filtering parameters based on signal characteristics or environmental changes, such as adaptive Kalman filtering, adaptive Wiener filtering, or machine learning-based filtering methods. This filtering process aims to remove random noise and interference from the data while preserving as much accurate instantaneous current fluctuation information as possible. Its purpose is to improve the signal-to-noise ratio of the data, providing clearer and more accurate input for subsequent adjustment decisions.

[0118] Furthermore, periodically inputting reference signals into multiple sampling channels and evaluating the performance drift of these channels based on their responses to the reference signals to generate calibration parameters involves injecting a standard current or voltage signal of known waveform and amplitude into all sampling channels at preset time intervals or under specific conditions. By comparing the difference between the output response of each sampling channel and the expected response of the reference signal, the performance drift of each channel, such as gain drift, zero-point drift, or response time deviation, can be quantified. Based on these evaluation results, a set of calibration parameters can be generated to compensate for the measurement errors of each channel. The purpose is to maintain the measurement accuracy of the sampling system over the long term and to offset performance degradation caused by component aging or environmental changes. Therefore, correcting the filtered instantaneous current fluctuation data based on the calibration parameters means applying the generated calibration parameters to the filtered instantaneous current fluctuation data to compensate and adjust the data. For example, additive or multiplicative corrections can be used to correct data offset or proportional errors, resulting in corrected instantaneous current fluctuation data that is closer to the true value. The purpose is to further improve the accuracy and consistency of the data, providing a solid foundation for precise control of the bypass current.

[0119] In some preferred embodiments, this application is implemented as follows:

[0120] Assume that the bypass current channel is configured with three independent Hall current sensors as sampling channels. During the establishment of the bypass current channel, these three Hall current sensors acquire current data in parallel at a high-frequency sampling frequency of 1MHz. The raw current data output by each sensor is first processed by a digital high-pass filter to extract transient components, obtaining their respective instantaneous current fluctuation data. Subsequently, the system performs real-time consistency verification on these three instantaneous current fluctuation data, for example, calculating the median of the three data and setting a deviation threshold (e.g., ±5%). If the deviation of any data from the median exceeds the threshold, the data is considered abnormal and discarded, and only the remaining valid data is used. Next, an adaptive Kalman filter is applied to the verified data. This filter can dynamically adjust the filter gain according to the real-time noise covariance and measurement covariance to effectively suppress noise and smooth the data. In addition, the system injects a known 1A square wave reference current signal into the bypass current channel every hour and records the response of the three Hall current sensors. By comparing the actual response with the ideal response, the gain error and zero-point drift of each sensor are evaluated, and corresponding calibration parameters are generated. Finally, these calibration parameters are applied to the Kalman-filtered instantaneous current fluctuation data for linear correction. For example, the corrected data = (filtered data - zero-point drift) / (1 + gain error) to obtain the final corrected instantaneous current fluctuation data. This high-precision, high-reliability instantaneous current fluctuation data will be used to precisely adjust the bypass current build-up slope and segmented switching timing.

[0121] In another embodiment of this application, S3300 specifically includes:

[0122] S3310: Obtain the electrochemical characteristic parameters of each individual cell, including internal resistance, capacity, and the formation rate of the solid electrolyte interface film;

[0123] S3320: Based on the electrochemical characteristic parameters, establish current fluctuation response thresholds for each individual cell. The current fluctuation response thresholds include peak thresholds and duration thresholds. The peak threshold is used to limit the peak value of instantaneous current fluctuations, and the duration threshold is used to limit the duration of instantaneous current fluctuations.

[0124] S3330: The process of establishing the bypass current channel is divided into multiple switching segments, and the switching interval and duration of each switching segment are set, thereby forming a segmented switching sequence.

[0125] S3340: When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation in the bypass current channel corresponding to any single cell exceeds its corresponding current fluctuation response threshold, the first adjustment is made to the establishment slope and / or segmented switching timing of the bypass current corresponding to the single cell:

[0126] S3350: In response to the peak value of the instantaneous current fluctuation exceeding the peak threshold, the slope of the bypass current establishment is adjusted according to the formation rate of the solid electrolyte interface film; in response to the duration of the instantaneous current fluctuation exceeding the duration threshold, the conduction duration of the power switching element in the bypass current channel is adjusted according to the internal resistance and capacity, and the duration of each switching segment and / or the switching interval time in the segmented switching sequence are adjusted accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls back to the current fluctuation response threshold and the bypass current change rate does not exceed the bypass current change rate safety threshold.

[0127] Specifically, electrochemical characteristic parameters refer to key indicators reflecting the internal chemical and physical properties of a single battery cell. Among them, internal resistance characterizes the degree to which the cell impedes current flow, capacity indicates the cell's ability to store charge, and the formation rate of the solid electrolyte interface film is closely related to the cell's cycle life and safety. These parameters can be obtained through online measurement, offline testing, or estimation based on historical data.

[0128] Furthermore, the current fluctuation response threshold is dynamically set based on the electrochemical characteristic parameters of each individual cell, aiming to provide personalized safety boundaries for instantaneous current fluctuations. The peak threshold is used to limit the maximum amplitude of instantaneous current fluctuations to prevent excessive current surges from damaging the cell. The duration threshold is used to limit the duration of instantaneous current fluctuations to avoid the cumulative impact of long-term fluctuations on cell performance. These thresholds can be finely configured according to the cell type, health status, and application scenario.

[0129] The process of establishing the bypass current channel is divided into multiple switching segments, meaning that the bypass current is not established all at once, but gradually increased through a series of step-by-step switching operations. Each switching segment has a preset switching interval and duration, which together constitute the segmented switching sequence to smooth the current establishment process and reduce transient impacts.

[0130] When instantaneous current fluctuation information indicates that the instantaneous current fluctuation in the bypass current channel corresponding to a single cell exceeds its preset current fluctuation response threshold, the first adjustment is triggered. Specifically, if the peak value of the instantaneous current fluctuation exceeds the peak value threshold, the establishment slope of the bypass current is adjusted according to the formation rate of the solid electrolyte interface film of the single cell. For example, if the formation rate of the solid electrolyte interface film is high, indicating that it is more sensitive to current surges, a gentler bypass current establishment slope is used to reduce the impact on the film. If the duration of the instantaneous current fluctuation exceeds the duration threshold, the conduction duration of the power switching element in the bypass current channel is adjusted according to the internal resistance and capacity of the single cell, and the duration of each switching segment and / or the switching interval time in the segmented switching sequence are adjusted accordingly. The purpose is to control the duration of the bypass current so that the instantaneous current fluctuation falls back to within the current fluctuation response threshold, while ensuring that the rate of change of the bypass current does not exceed the preset bypass current change rate safety threshold.

[0131] In some preferred embodiments, the following specific example illustrates the situation:

[0132] Suppose that during the lithium battery formation and capacity testing process, a bypass current channel is being established in a single cell. The system acquires real-time current change data in this channel and identifies instantaneous current fluctuations. For example, at a certain moment, the system detects that the peak value of the instantaneous fluctuation in the bypass current of this single cell exceeds its preset peak threshold. At this time, the system immediately acquires the formation rate of the solid electrolyte interface film of this single cell. Assuming that the solid electrolyte interface film formation rate of this single cell is high, it indicates that it is more sensitive to current surges. Based on this information, the system will perform the first adjustment, adjusting the bypass current establishment slope from the original 0.5A / ms to 0.3A / ms, establishing the bypass current at a more gradual rate, thereby effectively suppressing transient voltage spikes caused by rapid current rise.

[0133] For example, in another scenario, the system detects that the duration of a momentary fluctuation in the bypass current of a single battery cell exceeds its preset duration threshold, indicating that the current fluctuation has failed to decay rapidly. In this case, the system obtains the internal resistance and capacity of the single battery cell. Assuming the cell's internal resistance is slightly high and its capacity has decreased, this may result in a slower response to persistent fluctuations. Based on these parameters, the system adjusts the conduction duration of the power switching elements in the bypass current path. For example, the switching duration is shortened from 100 microseconds to 80 microseconds, and the switching interval is adjusted accordingly to increase the current switching frequency, thereby more quickly bringing the momentary current fluctuation back within the current fluctuation response threshold. Throughout the adjustment process, the system continuously monitors the bypass current change rate to ensure it never exceeds the preset bypass current change rate safety threshold, such as 1A / ms, to guarantee operational safety.

[0134] Another embodiment of this application further proposes a method for adjusting the establishment slope of the bypass current and / or the segmented switching timing based on current change data, which further includes:

[0135] S3400: Generate adjustment instructions. The adjustment instructions are used to indicate the adjustment of the bypass current establishment slope and / or segmented switching timing. The adjustment instructions include timestamp information and check code information.

[0136] S3500: Sends the adjustment command to the execution terminal of the bypass current channel corresponding to the target single cell;

[0137] S3600: After receiving the adjustment instruction, the execution end verifies the adjustment instruction based on the check code information;

[0138] S3700: When the verification passes, the timeliness of the adjustment instruction is determined based on the timestamp information, and the adjustment instruction is executed or discarded in response to the timeliness of the adjustment instruction;

[0139] S3800: Receives the execution status feedback information output by the execution end after executing the adjustment instruction, judges the execution status of the adjustment instruction based on the execution status feedback information, and resends the adjustment instruction and / or adjusts the subsequent adjustment strategy in response to the execution status.

[0140] Specifically, the adjustment command can be understood as a digital signal or data packet used to control the bypass current establishment slope and / or segmented switching timing. The timestamp information records the time the command was generated to ensure its timeliness and prevent the execution of outdated or invalid commands. Checksum information, such as a Cyclic Redundancy Check (CRC) code or hash value, is used to verify whether the command has been erroneous or tampered with during transmission, ensuring the integrity and accuracy of the command. The execution end can be understood as the hardware module or controller in the bypass current channel responsible for receiving and executing the adjustment command, such as a microcontroller, digital signal processor, or application-specific integrated circuit (ASIC). Execution status feedback information refers to the information returned by the execution end to the control system after attempting to execute the adjustment command, regarding the command execution result, such as successful execution, execution failure, parameter error, or equipment failure.

[0141] This application improves the reliability of adjustment instructions during transmission and execution by introducing mechanisms for the generation, transmission, verification, timeliness judgment, and execution feedback of adjustment instructions.

[0142] In some preferred embodiments, assuming that during the lithium battery formation and capacity testing process, the system detects current fluctuations in the bypass current channel exceeding a safety threshold, requiring immediate adjustment of the bypass current establishment slope, the control unit generates an adjustment command. This command includes not only the new establishment slope parameters but also the current timestamp information and a checksum calculated based on the command content. For example, the timestamp could be the current system time, and the checksum could be CRC-16. This adjustment command is then sent to the execution terminal of the bypass current channel corresponding to the target cell, which may be a dedicated power switch controller. Upon receiving the command, the execution terminal first verifies the received command using a built-in verification algorithm. If the checksum does not match, indicating a possible error during transmission, the execution terminal discards the command and sends a verification failure feedback message to the control unit. Upon receiving this feedback, the control unit regenerates and sends the adjustment command. If the verification passes, the execution terminal further checks the timestamp information in the command. If the timestamp indicates that the command has expired (e.g., exceeding a preset valid time window), the execution terminal also discards the command and sends an expiration feedback message. The executor will only adjust the bypass current establishment slope according to the instruction content if the verification passes and the instruction is within its valid timeframe. After execution, the executor will send feedback information indicating success or failure to the control unit. If the feedback information indicates failure, the control unit can, according to preset strategies, such as attempting to resend the instruction or adjusting subsequent adjustment strategies, to ensure effective control of the bypass current. In this way, even in the presence of communication interference or occasional malfunctions of the executor, the accuracy and reliability of bypass current adjustment can be ensured.

[0143] Another embodiment of this application further proposes that, prior to the aforementioned first adjustment, it also includes:

[0144] S3341: Obtain historical operating data for each individual battery cell. The historical operating data includes the number of charge / discharge cycles, cumulative operating time, and temperature change records.

[0145] S3342: Based on the current electrochemical characteristic parameters and historical operating data, evaluate the degree of drift of the electrochemical characteristic parameters of each individual cell, and predict the trend of the sensitivity change of each individual cell to instantaneous current fluctuations within a preset time window.

[0146] S3343: Based on the drift degree and sensitivity change trend, dynamically update the current fluctuation response threshold corresponding to each individual cell, and / or correct the initial setting value of the bypass current establishment slope, and / or correct the initial setting value of the conduction duration of the power switching element in the bypass current channel.

[0147] S3344: When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, a first adjustment is made based on the initial setting value of the corrected setup slope and / or the initial setting value of the corrected conduction duration.

[0148] Specifically, acquiring historical operating data for each individual battery cell refers to continuously recording and storing key operating parameters of each individual cell throughout its entire lifecycle through a battery management system (BMS) or testing system. Historical operating data may include, but is not limited to, the number of charge-discharge cycles for each individual cell (the total number of complete charge-discharge cycles the cell has undergone); cumulative operating time (the total time the cell has been in operation); and temperature change records (the temperature range and trend experienced by the cell at different operating stages). This data is used to assess the aging status and performance degradation of the cells.

[0149] The evaluation of the drift of electrochemical characteristic parameters of each individual cell based on current electrochemical characteristic parameters and historical operating data can be understood as comparing the cell's current electrochemical characteristic parameters, such as internal resistance, capacity, and solid electrolyte interphase (SIE) formation rate, with their initial or historical baseline values, and quantifying the degree of deviation by combining historical operating data (such as high cycle counts, prolonged high-temperature operation, etc.). For example, a significant increase in internal resistance or a significant decrease in capacity can be considered drift. Predicting the trend of sensitivity of each individual cell to instantaneous current fluctuations within a preset time window refers to using machine learning or empirical models, based on historical operating data and the degree of drift, to predict whether the cell's response characteristics to current fluctuations will become more sensitive in the future (e.g., more prone to voltage spikes or more sensitive to bypass current adjustments).

[0150] In practical applications, dynamically updating the current fluctuation response threshold for each individual battery cell based on the degree of drift and the trend of sensitivity changes means adjusting the threshold used to limit the peak value and duration of instantaneous current fluctuations in real time based on the cell's aging state and sensitivity prediction results. For example, for cells with a high degree of aging or predicted increased sensitivity, their current fluctuation response threshold is tightened to trigger adjustments under smaller fluctuations. And / or correcting the initial setting value of the bypass current build-up slope means adjusting the rate of increase of the bypass current in the initial build-up stage based on the cell's current state and predicted trend. For example, for cells with high sensitivity, the initial setting value of the build-up slope is reduced to decrease the initial impact. And / or correcting the initial setting value of the conduction duration of the power switching elements in the bypass current channel means adjusting the initial conduction time of the power switching elements in each switching segment to more finely control the duration of the bypass current.

[0151] Therefore, when the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, a first adjustment is made based on the initial setting value of the corrected establishment slope and / or the initial setting value of the corrected conduction duration. That is, the first adjustment takes the dynamically evaluated parameters as the starting point, rather than using the static initial setting value, so that the adjustment is more in line with the actual operating state and aging degree of the cell.

[0152] The solution proposed in this application assesses the drift of electrochemical characteristic parameters and predicts the trend of sensitivity to instantaneous current fluctuations by introducing historical operating data and combining it with current electrochemical characteristic parameters. This allows the initial settings of the current fluctuation response threshold, the slope of the bypass current build-up, and the conduction duration of the power switching element to be dynamically updated and corrected, avoiding threshold mismatch or improper parameter adjustment due to cell aging. When the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, the first adjustment is made based on the corrected initial settings, which makes the bypass equalization operation response more accurate and efficient, and continuously suppresses transient voltage spikes.

[0153] In some preferred embodiments, assuming that during the formation and capacity testing of a lithium battery pack, the internal resistance of a single cell increases by 20% after 500 charge-discharge cycles and 1000 hours of operation, and its temperature change records show that the cell was exposed to a high-temperature environment for an extended period. First, the system acquires historical operating data for the single cell, including the number of charge-discharge cycles, cumulative operating time, and temperature change records. Second, based on the current electrochemical characteristic parameters (such as internal resistance and capacity) and this historical operating data, the system assesses that the electrochemical characteristic parameters of the single cell exhibit significant drift and predicts that its sensitivity to instantaneous current fluctuations will further increase in the next 100 cycles. Based on this degree of drift and sensitivity trend, the system dynamically updates the current fluctuation response threshold corresponding to the single cell, for example, reducing the peak threshold from 50mA to 40mA and shortening the duration threshold from 100us to 80us. Simultaneously, the system also corrects the initial setting of the bypass current establishment slope, making it smoother when establishing the bypass current channel. For example, the initial slope is adjusted from 1A / ms to 0.8A / ms. If, during subsequent testing, a transient current fluctuation is detected in the bypass current channel of this single cell, and its peak value reaches 45mA (exceeding the updated 40mA threshold), the system will make its first adjustment based on the corrected 0.8A / ms establishment slope, instead of using the original 1A / ms slope. This proactive adjustment, based on historical data and predictions, allows the bypass equalization operation to respond earlier and more accurately to the actual state of the cell, thereby more effectively suppressing transient voltage spikes and avoiding damage to the cell.

[0154] Another embodiment of this application further proposes a method for correcting the initial setting value of the bypass current establishment slope, the specific steps of which include:

[0155] S3343-1: Obtain the formation stage information of each individual cell. The formation stage information includes the current state of charge of the individual cell and the thickness of the solid electrolyte interface film that has been formed.

[0156] S3343-2: Based on the formation stage information, drift degree and sensitivity change trend, select a nonlinear slope adjustment curve that matches the state of the individual cell from the preset set of nonlinear slope adjustment curves;

[0157] S3343-3: Based on the nonlinear slope adjustment curve, determine the target change law of the bypass current change rate with time during the bypass current channel establishment period, and generate the adjustment amount used to correct the establishment slope of the bypass current.

[0158] S3343-4: Correct the initial setting value of the bypass current establishment slope according to the adjustment amount.

[0159] Specifically, formation stage information refers to data related to the electrochemical activation process experienced by a single cell during its first charge cycle in lithium battery production. This information is used to understand and predict the cell's behavior during bypass equalization operations. Among these, the current state of charge (SOC) of a single cell reflects the available energy of the active materials within the cell; its level affects the cell's response speed to current changes and its internal impedance. The thickness of the formed solid electrolyte interphase (SEI) film is a key indicator of the formation process. The formation and stability of the SEI film significantly impact the cell's cycle life and safety. Different SEI film thicknesses alter the cell's interfacial impedance and ion transport characteristics, thus affecting the transient response during bypass current establishment.

[0160] The set of nonlinear slope adjustment curves is a pre-designed set of curves or curves obtained through experimental data and simulation models. Each curve represents the ideal or optimized law of the rate of change of bypass current over time under a specific cell state. These curves can be polynomial functions, exponential functions, or other nonlinear functions, designed to more precisely control the rise or fall of current to adapt to the electrochemical characteristics of the cell at different formation stages. By combining information on formation stages, drift degree, and sensitivity change trends, the nonlinear slope adjustment curve that best matches the current state of the individual cell can be selected from this set. For example, for cells with thin SEI films and low internal resistance, a curve with a gentle initial slope that gradually accelerates later can be selected to avoid impacting the newly formed SEI film; while for cells with stable SEI films and high internal resistance, a curve with a smoother overall slope can be selected.

[0161] Based on the selected nonlinear slope adjustment curve, the target variation law of the bypass current change rate with time during the bypass current channel establishment period can be determined. This law is no longer a simple linear slope but changes dynamically with time to match the transient response characteristics of the cell. Based on this target variation law, an adjustment amount is generated to correct the establishment slope of the bypass current. This adjustment amount can be an increment or decrement relative to the initial setting value, or it can be a direct specification of a new slope parameter. Finally, the initial setting value of the bypass current establishment slope is corrected accordingly, making the bypass current establishment process more refined and adaptive.

[0162] The proposed solution comprehensively assesses the real-time status of a single battery cell by incorporating information on the formation stage of the cell and combining it with the drift of electrochemical characteristic parameters and the changing trend of sensitivity to instantaneous current fluctuations. Compared to slope correction methods that rely solely on general parameters or linear models, this solution, based on formation stage information such as the current state of charge and the thickness of the formed solid electrolyte interface film, can more accurately characterize the cell's ability to withstand current surges. Furthermore, it selects a matching curve from a pre-set set of nonlinear slope adjustment curves, allowing the slope of the bypass current to dynamically change according to nonlinear laws during the initial, middle, and near-target current stages.

[0163] For example, when the cell is more sensitive to current changes in the early stages of SEI film formation, a curve with a smaller initial slope can be selected to avoid excessive current surges that could cause SEI film rupture or uneven growth. After the SEI film stabilizes, the slope can be appropriately increased to accelerate the equilibration process. Thus, the correction of the bypass current establishment slope is transformed from a "fixed value or simple adjustment value" to a nonlinear optimization based on the cell's "personalized" state. This more effectively reduces transient voltage spikes caused by the interaction between rapid bypass current switching and parasitic inductance, making it particularly suitable for the cell state-sensitive formation stage.

[0164] In some preferred embodiments, the following specific example illustrates the situation:

[0165] Suppose that during the lithium battery formation and capacity testing process, a single cell A is identified as the target cell requiring bypass equalization. When correcting the bypass current establishment slope, the formation stage information of cell A is first obtained. Specifically, through the battery management system (BMS) or dedicated sensors, it is determined that cell A's current state of charge is 80%, and the thickness of the formed solid electrolyte interface film is 50 nanometers. Simultaneously, combining historical operating data and evaluation of electrochemical characteristic parameters, it is determined that cell A's internal resistance drift is moderate, and its sensitivity to instantaneous current fluctuations gradually decreases. Based on this information, the system will select from a set of preset nonlinear slope adjustment curves. For example, the set includes curves designed for different stages such as "early stage of SEI film formation", "SEI film stabilization period" and "SEI film aging period". According to the state of charge, SEI film thickness, drift degree and sensitivity of cell A, the system selects a nonlinear slope adjustment curve with "moderate sensitivity during the SEI film stabilization period". This curve has a relatively gentle slope in the initial stage of bypass current establishment, and then the slope gradually increases. When it approaches the target current, the slope becomes gentle again. Based on this curve, the system calculates the target change law of the bypass current rate over time during the bypass current channel establishment period. For example, the bypass current rises at a rate of 50mA / ms in the first 100 milliseconds, at a rate of 100mA / ms in the next 200 milliseconds, and finally rises steadily at a rate of 20mA / ms before reaching the target current. Based on this, an adjustment amount is generated to correct the establishment slope of the bypass current. For example, if the initial setting is 70mA / ms and the average target slope calculated from the curve is 80mA / ms, then the adjustment amount is +10mA / ms. Finally, the initial setting of the bypass current establishment slope is adjusted from 70mA / ms to 80mA / ms, and the bypass current is established according to the dynamic slope indicated by the selected nonlinear curve, thereby achieving efficient and precise current control while protecting the battery cell.

[0166] Reference Figure 2 This application proposes a lithium battery formation, capacity testing, health monitoring, and performance diagnosis system, the system comprising:

[0167] Voltage data acquisition module 1 is used to acquire the voltage data of each individual cell in the battery pack, and identify the target individual cell that needs to be bypassed and balanced based on the voltage data.

[0168] Bypass channel establishment module 2 is used to perform bypass balancing operation in response to the identification of target single cell: for the target single cell, a bypass current channel is gradually established at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, in order to suppress transient voltage spikes caused by the rapid switching interaction between parasitic inductance and current in the internal connecting wires of the battery pack and the test system circuit.

[0169] The current data acquisition module 3 is used to acquire the current change data in the bypass current channel in real time during the establishment of the bypass current channel, and adjust the establishment slope of the bypass current and / or the segmented switching sequence according to the current change data, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate.

[0170] The bypass channel cancellation module 4 is used to gradually reduce the bypass current until the bypass current channel is removed at the end of the bypass balancing operation, according to the corrected bypass current change rate, and to ensure that the bypass current change rate during the gradual reduction of the bypass current does not exceed the bypass current change rate safety threshold.

[0171] This application modularizes the health monitoring and performance diagnosis functions in the formation and capacity testing of lithium batteries, forming a collaborative system.

[0172] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for lithium battery formation, capacity testing, health monitoring, and performance diagnosis, characterized in that, The method includes: Obtain the voltage data of each individual cell in the battery pack, and identify the target individual cell that needs to be bypassed and balanced based on the voltage data. In response to the identification of the target single cell, a bypass balancing operation is performed: a bypass current channel is gradually established for the target single cell at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, in order to suppress transient voltage spikes caused by the rapid switching interaction between parasitic inductance and current in the internal connecting wires of the battery pack and the test system circuit. During the establishment of the bypass current channel, the current change data in the bypass current channel is acquired in real time, and the establishment slope of the bypass current and / or the segmented switching sequence are adjusted according to the current change data to ensure that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate. When the bypass balancing operation ends, the bypass current is gradually reduced until the bypass current channel is removed according to the corrected bypass current change rate, and the bypass current change rate during the gradual reduction of the bypass current does not exceed the bypass current change rate safety threshold.

2. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 1, characterized in that, Adjusting the bypass current establishment slope and / or segmented switching timing based on the current change data to ensure that the bypass current change rate does not exceed a preset bypass current change rate safety threshold includes: Obtain the voltage data of each individual battery cell; Based on the voltage data, a charging current adjustment command is generated for each individual battery cell. The charging current applied to the target single cell is gradually reduced at a preset rate of change of charging current. During the gradual reduction of the charging current of the target single cell, the establishment slope of the bypass current and / or the segmented switching sequence are adjusted in combination with the current change data. This ensures that the rate of change of the bypass current meets the safety threshold of the bypass current change rate while reducing the instantaneous fluctuations caused by the interaction between the switching edge of the bypass current channel and the parasitic inductance, thereby suppressing the superimposed fluctuation components of the transient voltage spike.

3. The method for lithium battery formation, capacity testing, health monitoring, and performance diagnosis according to claim 1, characterized in that, The method further includes: During the bypass equalization operation, the voltage change rate signal across the power switching element in the bypass current channel is acquired, and the deviation data of the switching transient characteristics of the power switching element relative to the preset characteristics is determined based on the voltage change rate signal. Based on the deviation data, the performance drift data of the power switching element is obtained; The drive signal parameters of the power switching element are adaptively adjusted based on the deviation data to compensate for the performance drift of the power switching element. Based on the deviation data and the driving signal parameters, the segmented switching timing of the bypass current channel is corrected; Record the performance drift data, and update the adaptive adjustment strategy and / or output maintenance warning information based on the performance drift data.

4. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 1, characterized in that, Real-time acquisition of current change data in the bypass current channel, and adjustment of the bypass current establishment slope and / or segmented switching timing based on the current change data, including: During the establishment of the bypass current channel, the current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain the current change data. The transient component is extracted from the current change data to obtain instantaneous current fluctuation data reflecting the instantaneous current fluctuation in the bypass current channel. The instantaneous current fluctuation data is processed to identify instantaneous current fluctuation information; The slope of the bypass current establishment is adjusted based on the instantaneous current fluctuation information, and / or the segmented switching sequence of the bypass current is adjusted.

5. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 4, characterized in that, The current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain the current change data. Transient component extraction is performed on the current change data to obtain instantaneous current fluctuation data reflecting the instantaneous current fluctuations in the bypass current channel, including: The current in the bypass current channel is sampled in parallel using multiple independent sampling channels at the high-frequency sampling rate, and the current change data corresponding to each sampling channel is obtained respectively. Transient components are extracted from the current change data corresponding to each sampling channel to obtain the instantaneous current fluctuation data corresponding to each sampling channel. Real-time data consistency verification is performed on the instantaneous current fluctuation data acquired in parallel from multiple independent sampling channels to identify and remove abnormal data, thereby obtaining verified instantaneous current fluctuation data. Adaptive filtering is applied to the verified instantaneous current fluctuation data to suppress noise, resulting in filtered instantaneous current fluctuation data. Reference signals are periodically input into multiple sampling channels, and the performance drift of multiple sampling channels is evaluated based on the response of multiple sampling channels to the reference signals to generate calibration parameters; The corrected instantaneous current fluctuation data is obtained by correcting the filtered instantaneous current fluctuation data according to the calibration parameters.

6. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 4, characterized in that, Adjusting the establishment slope of the bypass current based on the instantaneous current fluctuation information, and / or adjusting the segmented switching sequence of the bypass current, including: The electrochemical characteristic parameters of each individual cell are obtained, including internal resistance, capacity, and the formation rate of the solid electrolyte interface film. Based on the electrochemical characteristic parameters, a current fluctuation response threshold is established for each individual cell. The current fluctuation response threshold includes a peak threshold and a duration threshold. The peak threshold is used to limit the peak value of the instantaneous current fluctuation, and the duration threshold is used to limit the duration of the instantaneous current fluctuation. The process of establishing the bypass current channel is divided into multiple switching segments, and a switching interval and a switching segment duration are set for each switching segment, thereby forming the segmented switching sequence. When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation in the bypass current channel corresponding to any single cell exceeds its corresponding current fluctuation response threshold, a first adjustment is made to the establishment slope and / or segmented switching timing of the bypass current corresponding to that single cell: In response to the peak value of the instantaneous current fluctuation exceeding the peak value threshold, the establishment slope of the bypass current is adjusted according to the formation rate of the solid electrolyte interface film. In response to the duration of the instantaneous current fluctuation exceeding the duration threshold, the conduction duration of the power switching element in the bypass current channel is adjusted according to the internal resistance and capacity, and the duration of each switching segment and / or the switching interval time in the segmented switching sequence are adjusted accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls back to within the current fluctuation response threshold, and the rate of change of the bypass current does not exceed the bypass current change rate safety threshold.

7. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 1, characterized in that, Adjusting the bypass current establishment slope and / or segmented switching timing based on the current change data also includes: An adjustment instruction is generated, which is used to indicate the adjustment of the establishment slope of the bypass current and / or the segmented switching timing, and the adjustment instruction includes timestamp information and check code information; The adjustment command is sent to the execution terminal of the bypass current channel corresponding to the target single cell; After receiving the adjustment instruction, the execution terminal verifies the adjustment instruction according to the check code information; Upon successful verification, the timeliness of the adjustment instruction is determined based on the timestamp information, and the adjustment instruction is executed or discarded in response to the timeliness of the adjustment instruction. The system receives execution status feedback information output by the execution terminal after executing the adjustment instruction, and determines the execution status of the adjustment instruction based on the execution status feedback information. In response to the execution status, the system resends the adjustment instruction and / or adjusts the subsequent adjustment strategy.

8. The lithium battery formation, capacity testing, health monitoring, and performance diagnosis method according to claim 6, characterized in that, Before making the first adjustment, it also includes: Acquire historical operating data for each individual battery cell, including charge / discharge cycle count, cumulative operating time, and temperature change records; Based on the current electrochemical characteristic parameters and the historical operating data, assess the degree of drift of the electrochemical characteristic parameters of each individual cell, and predict the trend of sensitivity change of each individual cell to the instantaneous current fluctuation within a preset time window. Based on the degree of drift and the trend of sensitivity change, the current fluctuation response threshold corresponding to each individual cell is dynamically updated, and / or the initial setting value of the establishment slope of the bypass current is corrected, and / or the initial setting value of the conduction duration of the power switching element in the bypass current channel is corrected. And when the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, the first adjustment is made based on the initial setting value of the corrected establishment slope and / or the initial setting value of the corrected conduction duration.

9. The method for lithium battery formation, capacity testing, health monitoring, and performance diagnosis according to claim 8, characterized in that, Correcting the initial setting value of the bypass current establishment slope includes: Obtain the formation stage information of each individual cell, including the current state of charge of the individual cell and the thickness of the solid electrolyte interface film formed. Based on the formation stage information, the degree of drift, and the sensitivity change trend, a nonlinear slope adjustment curve that matches the state of the individual cell is selected from a preset set of nonlinear slope adjustment curves. Based on the nonlinear slope adjustment curve, the target change law of the bypass current change rate with time during the establishment of the bypass current channel is determined, and an adjustment amount for correcting the establishment slope of the bypass current is generated accordingly. The initial setting value of the bypass current establishment slope is corrected according to the adjustment amount.

10. A lithium battery formation, capacity testing, health monitoring, and performance diagnosis system, characterized in that, include: The voltage data acquisition module is used to acquire the voltage data of each individual cell in the battery pack, and to identify the target individual cell that needs to be bypassed and balanced based on the voltage data. The bypass channel establishment module is used to perform bypass balancing operation in response to the identification of the target single cell: a bypass current channel is gradually established for the target single cell at a preset bypass current change rate, so that the bypass current gradually increases from zero or the initial value according to the bypass current change rate, so as to suppress transient voltage spikes caused by the rapid switching interaction of parasitic inductance and current in the internal connecting wires of the battery pack and the test system circuit. The current data acquisition module is used to acquire current change data in the bypass current channel in real time during the establishment of the bypass current channel, and adjust the establishment slope of the bypass current and / or the segmented switching sequence according to the current change data, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, so as to correct the bypass current change rate. The bypass channel cancellation module is used to gradually reduce the bypass current until the bypass current channel is removed at the end of the bypass balancing operation, according to the corrected bypass current change rate, and to ensure that the bypass current change rate during the gradual reduction of the bypass current does not exceed the bypass current change rate safety threshold.

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