A lithium battery formation and capacity test health monitoring and performance diagnosis method and system

Abstract

The application relates to the technical field of lithium batteries, in particular to a lithium battery formation and capacity test health monitoring and performance diagnosis method and system. The method comprises the following steps: acquiring voltage data and identifying a target single battery cell according to the voltage data; gradually establishing a bypass current channel for the target single battery cell, so that the bypass current gradually increases at a bypass current change speed from zero or an initial value; during the establishment of the bypass current channel, acquiring current change data of the bypass current channel in real time, and adjusting the establishment slope and / or segmented switching timing of the bypass current according to the current change data; and when the bypass equalization operation is completed, gradually reducing the bypass current at the corrected bypass current change speed until the bypass current channel is removed. The method solves the problem that, in the prior art, the bypass equalization operation in the lithium battery formation and capacity test process causes potential cumulative damage, and the existing test equipment cannot accurately capture and evaluate these transient influences.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium batteries, in particular to a lithium battery formation and capacity test health monitoring and performance diagnosis method and system. BACKGROUND

[0002] In the production and manufacturing of new energy automobile power batteries, the formation and capacity test activates the electrode material through multiple charge and discharge cycles, forms a stable solid electrolyte interface film (SEI film), and measures the actual capacity, which is a key process to ensure battery quality and performance. With the market's increasing demand for battery life and consistency and the expansion of production lines, the formation and capacity test is often long-term and high-intensity continuous operation. The battery pack composed of multiple single cells in series has higher requirements for cell consistency management during this process.

[0003] In existing tests, when a single cell first reaches the voltage upper limit during charging, the system usually closes the switch quickly to shunt the current through bypass equalization to protect the cell and allow other cells to continue charging. However, the rapid switching action of the bypass equalization switch will cause the current path to change abruptly in microseconds to milliseconds. Due to the parasitic inductance of the battery pack connection wires, busbars, and test lines, the rapid switching of current will induce transient voltage spikes or drops in the series system and propagate along the battery string, affecting other cells not bypassed.

[0004] The problem is that the data acquisition frequency of conventional test systems is usually low (such as hundreds of milliseconds or seconds), which is sufficient to record the slow changes of steady-state charge and discharge, but it is difficult to capture the microsecond / millisecond-level transient spikes. These spikes are either missed or averaged as "noise", making it difficult to identify, evaluate, and trace. Although the duration is extremely short, transient overvoltage can still have cumulative effects on the electrochemical health of other cells, especially during the SEI film formation stage, causing local electrolyte decomposition or film structure changes, which in turn reduces the density and uniformity of the SEI film, affecting the subsequent cycle stability and life consistency.

[0005] The existing technology needs to be improved to address the above problems. SUMMARY

[0006] The present application discloses a lithium battery formation and capacity test health monitoring and performance diagnosis method and system, aiming to solve the problem of potential cumulative damage to the electrochemical health of other cells not bypassed by transient voltage spikes caused by bypass equalization operation during the lithium battery formation and capacity test process in the prior art, and the difficulty of existing test equipment to accurately capture and evaluate these transient effects.

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

[0008] In a first aspect, the application discloses a lithium battery formation and capacity test health monitoring and performance diagnosis method, which comprises:

[0009] Obtaining voltage data of each single battery cell in the battery pack, and identifying a target single battery cell requiring bypass equalization operation according to the voltage data;

[0010] In response to identifying the target single battery cell, performing the bypass equalization operation: gradually establishing a bypass current channel for the target single battery cell at a preset bypass current change rate, and gradually increasing the bypass current from zero or an initial value at the bypass current change rate, so as to suppress transient voltage spikes caused by the interaction of the parasitic inductance of the internal connection wire of the battery pack and the test system line and the rapid switching of the current;

[0011] During the establishment of the bypass current channel, real-time acquisition of current change data of the bypass current channel is performed, and the establishment slope and / or segmented switching timing of the bypass current are adjusted 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;

[0012] At the end of the bypass equalization operation, the bypass current is gradually reduced until the bypass current channel is removed, and the bypass current change rate of the bypass current gradual reduction process does not exceed the bypass current change rate safety threshold.

[0013] Further, adjusting the establishment slope and / or segmented switching timing of the bypass current according to the current change data, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, comprises:

[0014] Obtaining voltage data of each single battery cell;

[0015] Generating a charging current adjustment instruction corresponding to each single battery cell according to the voltage data;

[0016] Gradually reducing the charging current applied to the target single battery cell at a preset charging current change rate, and adjusting the establishment slope and / or segmented switching timing of the bypass current in combination with the current change data during the gradual reduction process of the charging current of the target single battery cell, so that the bypass current change rate meets the bypass current change rate safety threshold while reducing the instantaneous fluctuation caused by the interaction of the switching edge of the bypass current channel and the parasitic inductance, so as to suppress the superimposed fluctuation component of the transient voltage spikes.

[0017] Further, the method further comprises:

[0018] During the bypass equalization operation, obtaining a voltage change rate signal across the power switch element of the bypass current channel, and determining deviation data of the switching transition characteristics of the power switch element relative to the preset characteristics according to the voltage change rate signal;

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

[0020] According to the deviation data, the driving signal parameters of the power switching element are adaptively adjusted to compensate for the performance drift of the power switching element;

[0021] According to the deviation data and the driving signal parameters, the segment switching timing of the bypass current channel is corrected;

[0022] The performance drift data is recorded, and the adaptive adjustment strategy is updated based on the performance drift data and / or output maintenance warning information.

[0023] Further, real-time current change data of the bypass current channel is obtained, and the establishment slope of the bypass current and / or the segment switching timing is 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, and the transient component of the current change data is extracted to obtain transient current fluctuation data reflecting the transient current fluctuation of the bypass current channel;

[0025] The transient current fluctuation data is processed to identify transient current fluctuation information;

[0026] Based on the transient current fluctuation information, the establishment slope of the bypass current is adjusted, and / or the segment switching timing of the bypass current is adjusted.

[0027] Further, the current of the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain current change data, and the transient component of the current change data is extracted to obtain transient current fluctuation data reflecting the transient current fluctuation of the bypass current channel, including:

[0028] Through a plurality of mutually independent sampling channels, the current of the bypass current channel is sampled in parallel at a high-frequency sampling frequency to obtain current change data corresponding to each sampling channel;

[0029] The transient component of the current change data corresponding to each sampling channel is extracted to obtain transient current fluctuation data corresponding to each sampling channel;

[0030] The real-time data consistency of the transient current fluctuation data obtained by the plurality of mutually independent sampling channels in parallel is checked to identify and eliminate abnormal data, to obtain checked transient current fluctuation data;

[0031] The adaptive filtering is applied to the checked transient current fluctuation data to suppress noise to obtain filtered transient current fluctuation data;

[0032] Periodically input a reference signal to a plurality of sampling channels, and evaluate performance drift of the plurality of sampling channels according to responses of the plurality of sampling channels to the reference signal, to generate a calibration parameter;

[0033] According to the calibration parameter, correct the filtered instantaneous current fluctuation data to obtain corrected instantaneous current fluctuation data.

[0034] Further, based on the instantaneous current fluctuation information, adjust the establishment slope of the bypass current and / or adjust the segment switching timing of the bypass current, including:

[0035] Obtain the electrochemical characteristic parameters of each single battery cell, including internal resistance, capacity and formation rate of solid electrolyte interface film;

[0036] According to the electrochemical characteristic parameters, establish a current fluctuation response threshold for each single battery cell, including a peak threshold and a duration threshold, wherein 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;

[0037] Divide the establishment process of the bypass current channel into a plurality of switching segments, and set switching interval time and switching segment duration for each switching segment, thereby forming a segmented switching timing;

[0038] When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation of the bypass current channel corresponding to any single battery cell exceeds its corresponding current fluctuation response threshold, the establishment slope and / or the segmented switching timing of the bypass current corresponding to the single battery cell are adjusted:

[0039] In response to the peak value of the instantaneous current fluctuation exceeding the peak 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 on duration of the power switch element of the bypass current channel is adjusted according to the internal resistance and the capacity, and the duration and / or the switching interval time of each switching segment of the segmented switching timing are adjusted accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls within the current fluctuation response threshold, and the change speed of the bypass current does not exceed the bypass current change rate safety threshold.

[0040] Further, adjusting the establishment slope and / or the segmented switching timing of the bypass current according to the current change data further includes:

[0041] Generate an adjustment instruction, the adjustment instruction being used to indicate adjustment of the establishment slope and / or the segmented switching timing of the bypass current, and the adjustment instruction containing timestamp information and check code information;

[0042] Send the adjustment instruction to the execution end of the bypass current channel corresponding to the target single battery cell.

[0043] The execution end receives the adjustment instruction, and checks the adjustment instruction according to the check code information;

[0044] When the check is passed, the timeliness of the adjustment instruction is judged according to the timestamp information, and the adjustment instruction is executed or discarded in response to the timeliness of the adjustment instruction;

[0045] The execution end receives the execution state feedback information output after executing the adjustment instruction, judges the execution of the adjustment instruction according to the execution state feedback information, and re-sends the adjustment instruction and / or adjusts the subsequent adjustment strategy in response to the execution.

[0046] Further, before the first adjustment, further comprising:

[0047] Obtain the historical running data of each single battery cell, the historical running data including the charge-discharge cycle number, the cumulative working time and the temperature change record;

[0048] According to the current electrochemical characteristic parameter and the historical running data, the drift degree of the electrochemical characteristic parameter of each single battery cell is evaluated, and the sensitivity change trend of each single battery cell to the instantaneous current fluctuation in a preset time window is predicted;

[0049] According to the drift degree and the sensitivity change trend, the current fluctuation response threshold corresponding to each single battery 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 switch element of the bypass current channel is corrected;

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

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

[0052] Obtain the formation stage information of each single battery cell, the formation stage information including the current state of charge of the single battery cell and the thickness of the formed solid-state electrolyte interface film;

[0053] According to the formation stage information, the drift degree and the sensitivity change trend, a nonlinear slope adjustment curve matched with the state of the single battery cell is selected from a preset nonlinear slope adjustment curve set;

[0054] According to the nonlinear slope adjustment curve, the target change law of the bypass current change speed 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;

[0055] An initial setting value of a build-up slope of the bypass current is corrected according to the adjustment amount.

[0056] In a second aspect, the application further discloses a lithium battery formation and capacity test health monitoring and performance diagnosis system, comprising:

[0057] A voltage data acquisition module is configured to acquire voltage data of each single battery cell in the battery pack, and identify a target single battery cell that needs to be subjected to a bypass equalization operation according to the voltage data;

[0058] A bypass channel establishment module is configured to, in response to the identification of the target single battery cell, perform the bypass equalization operation: gradually establishing a bypass current channel for the target single battery cell at a preset bypass current change rate, and gradually increasing the bypass current from zero or an initial value at the bypass current change rate, so as to suppress a transient voltage spike caused by the interaction of the parasitic inductance of the internal connection wire of the battery pack and the test system line and the rapid switching of the current.

[0059] A current data acquisition module is configured to acquire current change data of the bypass current channel in real time during the establishment of the bypass current channel, and adjust a build-up slope of the bypass current and / or a segmented switching timing according to the current change data, so as to correct the bypass current change rate, and make the bypass current change rate not exceed a preset bypass current change rate safety threshold.

[0060] A bypass channel revocation module is configured to, when the bypass equalization operation ends, gradually decrease the bypass current at the corrected bypass current change rate until the bypass current channel is removed, and make the bypass current change rate in the gradual decrease process of the bypass current not exceed the bypass current change rate safety threshold.

[0061] Beneficial effects: The method of the application can accurately control the establishment and revocation process of the bypass current, significantly reduce the amplitude and duration of the transient voltage spike through the gradual current change and real-time adjustment mechanism, and effectively avoid the potential cumulative damage to other single battery cells that are not bypassed. In addition, through real-time monitoring and correction of the bypass current change rate, the application overcomes the deficiency that the existing test equipment is difficult to accurately capture and evaluate the transient influence, and provides a more accurate and safe battery formation and capacity test solution, which is helpful to improve the long-term health status and performance stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 A flowchart of a lithium battery formation and capacity test health monitoring and performance diagnosis method provided by the application.

[0063] Figure 2 A program block diagram of a lithium battery formation and capacity test health monitoring and performance diagnosis system provided by the application.

[0064] In the figure: 1, voltage data acquisition module; 2, bypass channel establishment module; 3, current data acquisition module; 4, bypass channel revocation module. DETAILED DESCRIPTION

[0065] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0066] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0067] The conventional existing lithium battery formation and capacity test method has significant technical limitations when dealing with the consistency problem of single battery cells inside the battery pack, especially when starting the bypass equalization operation to protect the overvoltage battery cell. Specifically, the rapid switching action of the bypass equalization operation, due to the interaction of the parasitic inductance of the battery pack internal connection wire and the rapid switching of the current, is prone to cause transient voltage spikes. These short-time high-amplitude voltage fluctuations cause potential and cumulative damage to the electrochemical health status of other battery cells that are not bypassed, and existing test equipment often cannot accurately capture and evaluate these transient effects, resulting in the inability to effectively suppress these spikes, thereby affecting the long-term performance and life of the battery.

[0068] Reference Figure 1 To this end, the present application proposes a lithium battery formation and capacity test health monitoring and performance diagnosis method, the method comprising:

[0069] S1000: acquiring voltage data of each single battery cell in the battery pack, and identifying target single battery cells that need to be bypassed and equalized according to the voltage data;

[0070] S2000: In response to identifying the target monomer battery cell, a bypass equalization operation is performed: a bypass current channel is gradually established for the target monomer battery cell at a preset bypass current change rate, and the bypass current is gradually increased from zero or an initial value at the bypass current change rate, so as to suppress the transient voltage spike caused by the interaction of the parasitic inductance of the internal connection wire of the battery pack and the test system line and the rapid switching of the current;

[0071] S3000: During the establishment of the bypass current channel, the current change data of the bypass current channel is obtained in real time, and the establishment slope and / or segmented switching timing of the bypass current is adjusted 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.

[0072] S4000: At the end of the bypass equalization operation, the bypass current is gradually reduced until the bypass current channel is removed, and the bypass current change rate of the bypass current gradual reduction process does not exceed the bypass current change rate safety threshold.

[0073] Wherein, the "bypass equalization operation" refers to when the voltage of a certain monomer battery cell of the battery pack reaches a preset upper limit, a bypass current channel is established to shunt the charging current flowing to the cell, so as to avoid overcharging of the cell, and to allow other cells of the battery pack to continue charging, thereby achieving the balance of the state of charge among the cells. The "bypass current change rate" refers to the rate of change of the current value with time during the establishment or removal process of the bypass current, which is usually expressed in amperes per second (A / s). The "transient voltage spike" refers to the short-time, high-amplitude voltage fluctuation caused by the existence of circuit parasitic inductance when the current is rapidly switched (for example, the opening or closing of the bypass current channel). The "bypass current change rate safety threshold" refers to the maximum allowed value of the bypass current change rate set to ensure the safe and stable operation of the battery system.

[0074] The method proposed in the present application first obtains the voltage data of each monomer battery cell in the battery pack. The voltage data can be obtained in various ways, for example: using a high-precision voltage sensor to independently measure each monomer battery cell, and transmitting the measurement results to the processing unit through the data acquisition system; or using the voltage monitoring function built-in the battery management system (BMS) to periodically read the voltage values of each monomer battery cell. Based on the obtained voltage data, the target monomer battery cell that needs to be bypassed and equalized is identified, for example, when the voltage of a certain monomer battery cell exceeds a preset overvoltage threshold, the monomer battery cell is identified as the target monomer battery cell.

[0075] In response to identifying the target monomer battery cell, a bypass equalization operation is performed: for the target monomer battery 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 an initial value at the preset bypass current change rate. The establishment of the bypass current channel can be achieved in various ways, for example: controlling the conduction degree of one or more power switching elements (such as MOSFET or IGBT) to gradually increase the bypass current; or using a multi-stage bypass resistance network to gradually increase the bypass current by gradually switching resistors to simulate the effect of gradual increase. The gradual establishment is used to reduce di / dt, thereby suppressing transient voltage spikes.

[0076] During the establishment of the bypass current channel, the current change data of the bypass current channel is obtained in real time. The current change data can be obtained by real-time sampling of a high-frequency current sensor, for example, using a Hall effect current sensor, or continuously monitoring the bypass current by combining a shunt resistor with a high-precision sampling circuit. Based on the obtained current change data, the establishment slope and / or the segmented switching timing of the bypass current are adjusted to ensure that the bypass current change rate does not exceed the safety threshold, so as to correct the bypass current change rate. For example, when the current change rate is monitored to be too fast, the drive signal duty cycle of the power switching element can be reduced to slow down the current rise rate; when the bypass current channel uses a segmented switching method, the interval time of each switching segment can be extended or the current increment of each segment can be reduced.

[0077] At the end of the bypass equalization operation, the bypass current is gradually reduced until the bypass current channel is removed at the corrected bypass current change rate, and the bypass current change rate is continuously monitored during the gradual reduction of the bypass current to ensure that it does not exceed the safety threshold. The gradual reduction of the bypass current can also be achieved in various ways, for example, gradually reducing the conduction degree of the power switching element to smoothly decrease the bypass current, or gradually cutting off the bypass resistance to achieve stepwise reduction, thereby avoiding introducing new transient voltage spikes when the bypass current channel is removed.

[0078] The overall technical solution of the present application aims to solve the problem of transient voltage spikes caused by bypass equalization operation in traditional lithium battery formation and capacity test. In the traditional scheme, when a certain monomer battery cell reaches the upper limit of voltage, the bypass equalization function will be quickly started and the current will be shunted; due to the parasitic inductance of the internal connection wires of the battery pack and the test system circuit, the rapid switching will generate a transient voltage spike according to the inductance law (V = L * di / dt). Although the duration of the spike is short, the instantaneous amplitude can be high, and it can cause potential and cumulative damage to the electrochemical health state of other cells that are not bypassed, such as accelerating the degradation of the solid-state electrolyte interface film (SEI film), thereby affecting the long-term performance and life of the battery.

[0079] The essence of the present application is to implement "progressive + real-time feedback" fine control on the bypass current channel establishment and cancellation process: the progressive establishment is realized by the preset bypass current change speed to reduce di / dt; the current change data is obtained in real time during the establishment, and the establishment slope and / or segmented switching timing of the bypass current are dynamically adjusted, so that the bypass current change speed is always controlled within the bypass current change rate safety threshold; in the cancellation stage, the bypass current is also gradually reduced at the modified bypass current change speed and continuously controlled. In this way, the amplitude and occurrence probability of transient voltage spikes are minimized, the potential cumulative effects on other single cells in the battery pack (especially in the SEI film formation stage) are reduced, and the stability and reliability of the formation and capacity test are improved.

[0080] In another embodiment of the present application, the establishment slope and / or segmented switching timing of the bypass current are adjusted according to the current change data to ensure that the bypass current change speed does not exceed the preset bypass current change rate safety threshold, including:

[0081] S3001: Obtain voltage data of each single cell;

[0082] S3002: Generate charging current adjustment instructions corresponding to each single cell according to the voltage data;

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

[0084] Specifically, when performing bypass equalization operation, first, the voltage data of each single cell in the battery pack is obtained. Based on these voltage data, charging current adjustment instructions for each single cell are generated. The charging current adjustment instructions are used to control the charging device to apply a charging current to a specific single cell, so as to realize fine management of the charging state of the single cell.

[0085] In actual application, for the target single cell that needs to perform bypass equalization operation, the charging current applied thereto is gradually reduced at a preset charging current change speed, so as to smooth the total current change of the target single cell and reduce the current impact caused by the intervention of the bypass current.

[0086] During the bypass current channel establishment, real-time current change data in the bypass current channel is acquired, and the establishment slope of the bypass current and / or the segmented switching timing is dynamically adjusted in combination with the current change data, so that the bypass current change speed does not exceed the preset bypass current change rate safety threshold; at the same time, the instantaneous fluctuation caused by the interaction of the switching edge of the bypass current channel and the parasitic inductance is reduced through the dynamic adjustment, so that the superimposed fluctuation component of the transient voltage peak is suppressed.

[0087] In some preferred embodiments, the following is described by a specific example:

[0088] Suppose that during the lithium battery formation and capacity test process, the system identifies that the voltage of a certain single cell is too high and needs to be bypassed for equalization. Before starting the bypass equalization operation, the system first acquires the real-time voltage data of the target single cell. Based on these voltage data, the control system generates a charging current adjustment instruction, instructing the charging device to gradually reduce the charging current applied to the target single cell at a speed of, for example, 0.1A per second. At the same time, the bypass current channel begins to establish, and the bypass current gradually increases at a preset initial slope. During the establishment of the bypass current channel, the high-frequency current sensor monitors the current change data in the bypass current channel in real time. If the monitoring data shows that the switching edge of the bypass current produces an unexpected instantaneous fluctuation, for example, a slight oscillation occurs on the current rising edge, the system immediately dynamically adjusts the establishment slope of the bypass current to be more gentle or adjusts the segmented switching timing, for example, extends the duration of a certain switching segment or adjusts the switching interval, in combination with the current change data, to smooth the current transition. Through the coordinated action of the gradual reduction of the charging current and the fine adjustment of the bypass current, the instantaneous fluctuation caused by the interaction of the switching edge and the parasitic inductance can be effectively absorbed and suppressed, so that the superimposed fluctuation component of the transient voltage peak is avoided, and the stability and safety of the bypass equalization process are ensured.

[0089] In another embodiment of the present application, it is further proposed that the lithium battery formation and capacity test health monitoring and performance diagnosis method further comprises:

[0090] S5000: During the bypass equalization operation, the voltage change rate signal of the power switch element in the bypass current channel is acquired, and the deviation data of the switching transition characteristic of the power switch element relative to the preset characteristic is determined according to the voltage change rate signal;

[0091] S6000: According to the deviation data, the performance drift data of the power switch element is obtained;

[0092] S7000: The driving signal parameters of the power switch element are adaptively adjusted according to the deviation data to compensate for the performance drift of the power switch element;

[0093] S8000: Correct the segment switching timing of the bypass current channel according to the deviation data and the drive signal parameters.

[0094] S9000: Record the performance drift data, and update the adaptive adjustment strategy and / or output the maintenance warning information based on the performance drift data.

[0095] Wherein, the power switching element refers to a semiconductor device used for controlling the on-off of the current in the bypass current channel, such as MOSFET, IGBT, etc. The voltage rate of change signal at both ends usually refers to the rate of change of the drain-source (or collector-emitter) voltage with time (dV / dt) during the turn-on or turn-off process of the power switching element, which is used to directly reflect the switching speed and switching transition characteristics of the power switching element. The preset characteristics refer to the switching transition characteristics of the power switching element in the ideal state or initial calibration state. The deviation data refers to the difference between the switching transition characteristics reflected by the actually measured voltage rate of change signal and the preset characteristics, such as the change of the switching rise or fall time, the amplitude change of the overshoot or undershoot, etc.

[0096] The performance drift data refers to the change of the electrical characteristic parameters (such as on-resistance, threshold voltage, transconductance, etc.) of the power switching element caused by factors such as aging, temperature change, long-term work, etc., which is reflected or derived by the deviation data, and the change will directly affect the switching transition characteristics. The drive signal parameters refer to the signal characteristics used to control the turn-on and turn-off of the power switching element, such as the amplitude of the gate drive voltage, the pulse width, the slope of the rising edge and the falling edge, etc. The adaptive adjustment refers to dynamically modifying the drive signal parameters according to the real-time obtained deviation data, in order to offset or compensate the performance drift of the power switching element, so that its switching transition characteristics can be restored to the preset characteristics as much as possible. The segment switching timing refers to the time sequence of the current path through the coordinated work of multiple power switching elements in the establishment or revocation process; the correction of the segment switching timing is to make the overall change curve of the bypass current meet the preset bypass current change speed requirement when the power switching element has performance drift. Recording the performance drift data and updating the adaptive adjustment strategy aims to optimize the subsequent adjustment algorithm based on historical data, improve the adjustment accuracy and efficiency; outputting the maintenance warning information is used to prompt the operator to check or replace the power switching element that may have a fault.

[0097] In some preferred embodiments, the following is described by a specific example:

[0098] Assuming MOSFET is used as the power switching element in the bypass current channel. During the bypass equalization operation, the voltage rate of change (dV / dt) signal across the MOSFET drain-source is monitored in real time by 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 is detected to become flat, indicating that its switching speed has slowed down, this phenomenon is identified as a deviation of the switching transition characteristic from the preset characteristic. According to this deviation, the system infers the performance drift of the MOSFET, such as an increase in gate capacitance or a decrease in transconductance. To compensate for the drift, the control unit adaptively adjusts the gate drive signal parameters of the MOSFET, such as increasing the amplitude of the gate drive voltage or adjusting the width of the drive pulse, to speed up its switching process. At the same time, if the bypass current channel uses segmented switching, the system adjusts the duration and switching interval time of each segment according to the adjusted MOSFET switching transition characteristics to ensure that the overall slope of the bypass current remains within the preset bypass current rate of change safety threshold. The performance drift data and adjustment records are stored for subsequent analysis and optimization of the adaptive adjustment strategy, and a maintenance warning is sent to the operator when a serious drift is detected, prompting the replacement or inspection of the relevant power switching element.

[0099] In another embodiment of the present application, it is further proposed to obtain 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 timing 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, and the transient current fluctuation data reflecting the transient current fluctuation in the bypass current channel is obtained by extracting the transient component from the current change data;

[0101] S3200: Process the transient current fluctuation data to identify the transient current fluctuation information;

[0102] S3300: Adjust the establishment slope of the bypass current based on the transient current fluctuation information, and / or adjust the segmented switching timing of the bypass current.

[0103] Specifically, the current in the bypass current channel is sampled at a preset high-frequency sampling frequency, which aims 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 the transient voltage spikes caused by the interaction of the parasitic inductance in the battery pack internal connection wires and the test system lines with the rapid current switching. High-frequency sampling can ensure accurate reconstruction of the current waveform, providing a detailed data basis for subsequent analysis.

[0104] The transient component extraction on the current change data can be understood as removing the direct current or slow change component in the current change data by digital signal processing technology, such as high-pass filtering, wavelet transform or differential operation, so as to highlight and separate the instantaneous and rapid change current fluctuation component. These instantaneous current fluctuation data directly reflect the transient response generated by the bypass current channel when the switch is switched or the current slope is changed, and are the key basis for identifying potential transient voltage peaks.

[0105] In actual application, the instantaneous current fluctuation data is processed to identify the instantaneous current fluctuation information, which can specifically include threshold comparison, peak detection, duration analysis or frequency analysis on the extracted instantaneous current fluctuation data. For example, a current fluctuation peak threshold and a duration threshold can be set, and when the peak or duration of the instantaneous current fluctuation exceeds these thresholds, it is identified as the instantaneous current fluctuation information that needs to be paid attention to. The purpose is to convert the original fluctuation data into operable information with clear indication, so that the system can make decisions accordingly.

[0106] Further, the establishment slope of the bypass current is adjusted based on the identified instantaneous current fluctuation information, and / or the segment switching timing of the bypass current is adjusted. For example, when the identified instantaneous current fluctuation is too large, the establishment slope of the bypass current can be reduced to make the current change more gentle, thereby reducing the amplitude of the transient voltage peak; or the segment switching timing of the bypass current channel can be adjusted, such as extending the switching interval time or adjusting the duration of each switching segment, to avoid rapid switching at sensitive moments, thereby effectively suppressing the generation or superposition of the transient voltage peak.

[0107] The scheme of the present application introduces the mechanism of high-frequency sampling, transient component extraction and fluctuation information identification, so that the system can accurately perceive the instantaneous current fluctuation generated by the bypass current channel during the establishment process in real time. It is precisely because these subtle current changes can be obtained and analyzed in time that the system can adjust the establishment slope and / or segment switching timing of the bypass current. This fine real-time adjustment capability effectively avoids the transient voltage peak caused by the interaction of rapid current switching and parasitic inductance, thereby solving the problem that the traditional scheme cannot effectively suppress the transient voltage peak. Through accurate monitoring and feedback control of the instantaneous current fluctuation, the establishment process of the bypass current is optimized, ensuring that the current change is always within the preset bypass current change rate safety threshold, thereby significantly improving the stability and safety of the balancing operation.

[0108] In another embodiment of the present application, the current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain current change data, and the current change data is subjected to transient component extraction to obtain instantaneous current fluctuation data reflecting instantaneous current fluctuation in the bypass current channel, comprising:

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

[0110] S3120: The current change data corresponding to each sampling channel is subjected to transient component extraction to obtain instantaneous current fluctuation data corresponding to each sampling channel;

[0111] S3130: Real-time data consistency verification is performed on the instantaneous current fluctuation data obtained in parallel by the plurality of mutually independent sampling channels to identify and eliminate abnormal data, to obtain verified instantaneous current fluctuation data;

[0112] S3140: Adaptive filtering is applied to the verified instantaneous current fluctuation data to suppress noise to obtain filtered instantaneous current fluctuation data;

[0113] S3150: A reference signal is periodically input to the plurality of sampling channels, and the performance drift of the plurality of sampling channels is evaluated according to the response of the plurality of sampling channels to the reference signal to generate calibration parameters;

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

[0115] Specifically, the current in the bypass current channel is sampled in parallel through a plurality of mutually independent sampling channels, which means that at least two or more independent current sensors or sampling circuits are used to synchronously collect the current signal in the bypass current channel at the same time point or in a very short time interval. Each sampling channel works independently to obtain its own current change data, and its purpose is to provide data redundancy and cross-validation possibility to improve the reliability of original data acquisition. Among them, the current change data corresponding to each sampling channel is subjected to transient component extraction, which means that for the current data obtained by each independent sampling channel, signal processing techniques (such as high-pass filtering, wavelet transform or difference algorithm) are respectively used to separate the rapidly changing, non-steady-state current component, i.e. instantaneous current fluctuation data. 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 check on the instantaneous current fluctuation data acquired by multiple independent sampling channels in parallel can be understood as comparing and analyzing the instantaneous current fluctuation data from different sampling channels to determine whether there is a significant difference or abnormality between them. For example, the average, median or standard deviation of the data of each channel can be calculated, and a threshold can be set. When the data of a certain channel deviates from the data or statistical characteristics of other channels by more than the threshold, it is identified as abnormal data and is rejected. The purpose is to exclude false data caused by single sensor failure, line interference or transient error, and to ensure that the data for subsequent processing has high reliability.

[0117] Further, applying adaptive filtering to the verified instantaneous current fluctuation data to suppress noise means using an algorithm that can automatically adjust filtering parameters according to signal characteristics or environmental changes, such as adaptive Kalman filtering, adaptive Wiener filtering or machine learning-based filtering methods. The filtering process aims to remove random noise and interference present in the data while preserving as much real instantaneous current fluctuation information as possible, and its purpose is to improve the signal-to-noise ratio of the data and provide clearer and more accurate input for subsequent adjustment decisions.

[0118] In addition, periodically inputting a reference signal to multiple sampling channels and evaluating the performance drift of multiple sampling channels according to the response of multiple sampling channels to the reference signal to generate calibration parameters means injecting a standard current or voltage signal with a known waveform and amplitude into all sampling channels at a predetermined time interval or under certain conditions. By comparing the difference between the output response of each sampling channel and the expected response of the reference signal, the gain drift, zero drift or response time deviation of each channel 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. Its purpose is to maintain the measurement accuracy of the sampling system in the long term and offset the performance degradation caused by component aging or environmental changes. Therefore, correcting the filtered instantaneous current fluctuation data according to the calibration parameters means applying the calibration parameters generated above to the filtered instantaneous current fluctuation data for compensation and adjustment. For example, offset or proportional error of the data can be corrected by addition or multiplication correction, so as to obtain corrected instantaneous current fluctuation data closer to the true value. Its purpose is to further improve the accuracy and consistency of the data and provide a solid foundation for accurate control of the bypass current.

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

[0120] Suppose three mutually independent Hall current sensors are configured as sampling channels in the bypass current channel. During the establishment of the bypass current channel, the three Hall current sensors collect current data in parallel at a high sampling frequency of 1 MHz. The raw current data output by each sensor is first subjected to a digital high-pass filter to extract transient components, obtaining respective instantaneous current fluctuation data. Subsequently, the system performs real-time consistency checking on the three channels of instantaneous current fluctuation data, for example, calculates the median of the three channels of data, and sets a deviation threshold (for example, ±5%). If the deviation of a certain channel of data from the median exceeds the threshold, it is considered that the channel of data is abnormal and is discarded, and only the remaining valid data is used. Next, an adaptive Kalman filter is applied to the checked data, which can dynamically adjust the filtering gain according to the real-time noise covariance and measurement covariance to effectively suppress noise and smooth the data. In addition, the system will inject a known 1A square wave reference current signal into the bypass current channel every 1 hour, and record the responses of the three Hall current sensors. By comparing the actual response with the ideal response, the gain error and zero drift of each sensor are evaluated, and the corresponding calibration parameters are generated. Finally, these calibration parameters are applied to the instantaneous current fluctuation data after Kalman filtering to perform linear correction, for example, corrected data = (filtered data - zero drift) / (1 + gain error), thereby obtaining the final corrected instantaneous current fluctuation data. These high-precision and high-reliability instantaneous current fluctuation data will be used to accurately adjust the establishment slope and segmented switching timing of the bypass current.

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

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

[0123] S3320: Establish a current fluctuation response threshold for each single battery cell according to the electrochemical characteristic parameters, including a peak threshold and a duration threshold, wherein 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;

[0124] S3330: Divide the establishment process of the bypass current channel into multiple switching segments, and set a switching interval time and a switching segment duration for each switching segment, thereby forming a segmented switching timing;

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

[0126] S3350: in response to the peak value of the instantaneous current fluctuation exceeding a peak value threshold, performing the establishment slope adjustment of the bypass current according to the formation rate of the solid-state electrolyte interface film; in response to the duration of the instantaneous current fluctuation exceeding a duration threshold, performing the on duration adjustment of the power switching element in the bypass current channel according to the internal resistance and the capacity, and adjusting the duration of each switching segment and / or the switching interval time in the segmented switching timing accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls within the current fluctuation response threshold, and the bypass current change rate does not exceed the bypass current change rate safety threshold.

[0127] Specifically, the electrochemical characteristic parameter refers to a key indicator reflecting the internal chemical and physical properties of the single battery. Among them, the internal resistance characterizes the degree of hindering the flow of current inside the battery, the capacity indicates the ability of the battery to store charge, and the formation rate of the solid-state electrolyte interface film is closely related to the cycle life and safety of the battery. These parameters can be obtained by online measurement, offline test or estimation based on historical data.

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

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

[0130] When the instantaneous current fluctuation information indicates that the instantaneous current fluctuation in the bypass current channel corresponding to a certain single battery 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-state electrolyte interface film of the single battery cell. For example, if the formation rate of the solid-state electrolyte interface film is relatively high, indicating that it is relatively sensitive to current impact, a more moderate bypass current establishment slope is adopted 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 battery cell, and the duration of each switching segment and / or the switching interval time in the segmented switching timing is adjusted accordingly. The purpose is to control the duration of the bypass current, so that the instantaneous current fluctuation falls within the current fluctuation response threshold, while ensuring that the bypass current change rate does not exceed the preset bypass current change rate safety threshold.

[0131] In some preferred embodiments, the following is described by a specific example:

[0132] Assuming that during the lithium battery formation and capacity test process, the bypass current channel of a certain single battery cell is being established. The system obtains the current change data in the channel in real time and identifies the instantaneous current fluctuation information. For example, at a certain time, it is detected that the peak value of the instantaneous fluctuation of the bypass current of the single battery cell exceeds its preset peak value threshold. At this time, the system will immediately obtain the formation rate of the solid-state electrolyte interface film of the single battery cell. Assuming that the formation rate of the solid-state electrolyte interface film of the single battery cell is relatively high, indicating that it is relatively sensitive to current impact. Based on this information, the system will perform the first adjustment, adjusting the establishment slope of the bypass current from the original 0.5A / ms to 0.3A / ms, to establish the bypass current at a slower rate, thereby effectively suppressing the transient voltage spike caused by rapid rise of current.

[0133] For another example, in another scenario, the system detects that the duration of the instantaneous fluctuation of the bypass current of the single battery cell exceeds its preset duration threshold, indicating that the current fluctuation has not decayed rapidly. At this time, the system will obtain the internal resistance and capacity of the single battery cell. Assuming that the internal resistance of the single battery cell is slightly high and the capacity has decreased, which may cause it to respond slowly to persistent fluctuations. Based on these parameters, the system will adjust the conduction duration of the power switching element in the bypass current channel. For example, the switching segment duration is shortened from 100 microseconds to 80 microseconds, and the switching interval time is adjusted accordingly to increase the on-off frequency of the current, thereby more quickly falling the instantaneous current fluctuation within the current fluctuation response threshold. During the entire adjustment process, the system will continuously monitor the bypass current change rate to ensure that it always does not exceed the preset bypass current change rate safety threshold, for example, 1A / ms, to ensure the safety of the operation.

[0134] In another embodiment of the present application, the method for adjusting the establishment slope of the bypass current and / or the segment switching timing according to the current change data further comprises:

[0135] S3400: generating an adjustment instruction, the adjustment instruction being used to instruct adjustment of the establishment slope of the bypass current and / or the segment switching timing, and the adjustment instruction containing timestamp information and check code information;

[0136] S3500: sending the adjustment instruction to an execution end of a bypass current channel corresponding to the target single battery cell;

[0137] S3600: after the execution end receives the adjustment instruction, checking the adjustment instruction according to the check code information;

[0138] S3700: when the check passes, judging the timeliness of the adjustment instruction according to the timestamp information, and executing or discarding the adjustment instruction in response to the timeliness of the adjustment instruction;

[0139] S3800: receiving execution state feedback information output by the execution end after the execution of the adjustment instruction, judging the execution of the adjustment instruction according to the execution state feedback information, and re-sending the adjustment instruction and / or adjusting a subsequent adjustment strategy in response to the execution.

[0140] Specifically, the adjustment instruction can be understood as a digital signal or a data packet used to control the establishment slope of the bypass current and / or the segment switching timing. The timestamp information is used to record the time of generation of the instruction, so as to ensure the timeliness of the instruction and prevent the execution of outdated or invalid instructions. The check code information, such as a cyclic redundancy check code (CRC) or a hash value, is used to verify whether the instruction has errors or has been tampered with in the transmission process, so as to guarantee the integrity and accuracy of the instruction. The execution end can be understood as a hardware module or a controller, such as a microcontroller, a digital signal processor or an application-specific integrated circuit, which is responsible for receiving and executing the adjustment instruction in the bypass current channel. The execution state feedback information refers to information returned by the execution end to the control system about the execution result of the instruction after the execution of the adjustment instruction, such as successful execution, execution failure, parameter error or device failure, etc.

[0141] The present application introduces the generation, transmission, check, timeliness judgment and execution feedback mechanism of the adjustment instruction, thereby improving the reliability of the adjustment instruction in the transmission and execution process.

[0142] In some preferred embodiments, in case the system detects that the current fluctuation in the bypass current channel exceeds the safety threshold during the lithium battery formation and capacity test, the establishment slope of the bypass current needs to be adjusted immediately. At this time, the control unit will generate an adjustment instruction, which not only contains the new establishment slope parameter, but also carries the current timestamp information and the verification code calculated according to the content of the instruction. For example, the timestamp can be the current system time, and the verification code can be CRC-16. The adjustment instruction is then sent to the execution end of the bypass current channel corresponding to the target single cell, which can be a dedicated power switch controller. When the execution end receives the instruction, it will first verify the received instruction according to the built-in verification algorithm. If the verification code does not match, it means that the instruction may have been wrong during transmission, and the execution end will discard the instruction and send feedback information to the control unit indicating that the verification has failed. After receiving the feedback, the control unit will re-generate and send the adjustment instruction. If the verification is passed, the execution end will further check the timestamp information in the instruction. If the timestamp indicates that the instruction has expired (e.g., exceeds the preset valid time window), the execution end will also discard the instruction and send a feedback indicating that the timeliness has expired. Only when the verification is passed and the instruction is within the valid timeliness, the execution end will adjust the establishment slope of the bypass current according to the content of the instruction. After the execution is completed, the execution end will send feedback information to the control unit indicating the success or failure of the execution. If the feedback information indicates that the execution has failed, the control unit can adjust the subsequent adjustment strategy according to the preset strategy, such as trying to send the instruction again, or adjusting the subsequent adjustment strategy, to ensure the effective control of the bypass current. In this way, even in the case of communication interference or occasional failure of the execution end, the accuracy and reliability of the bypass current adjustment can be ensured.

[0143] In another embodiment of the present application, before the above-mentioned first adjustment, further comprising:

[0144] S3341: obtaining historical running data of each single cell, the historical running data including charge-discharge cycle number, cumulative working time and temperature change record;

[0145] S3342: evaluating the drift degree of the electrochemical characteristic parameter of each single cell according to the current electrochemical characteristic parameter and the historical running data, and predicting the sensitivity change trend of each single cell to instantaneous current fluctuation within a preset time window;

[0146] S3343: dynamically updating the current fluctuation response threshold corresponding to each single cell according to the drift degree and the sensitivity change trend, and / or correcting the initial setting value of the establishment slope of the bypass current, and / or correcting the initial setting value of the conduction duration of the power switch element in the bypass current channel;

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

[0148] Specifically, obtaining the historical operation data of each single battery cell refers to continuously recording and storing the key operation parameters of each single battery cell throughout its entire life cycle through the battery management system (BMS) or test system. The historical operation data can include but is not limited to the number of charge-discharge cycles of the single battery cell, i.e. the total number of complete charge-discharge cycles experienced by the battery cell; the cumulative working time, i.e. the total time of the battery cell in the working state; and the temperature change record, i.e. the temperature range and change trend experienced by the battery cell in different working stages. These data are used to evaluate the aging state and performance degradation of the battery cell.

[0149] Among them, according to the current electrochemical characteristic parameters and the historical operation data, the drift degree of the electrochemical characteristic parameters of each single battery cell can be understood as comparing the current electrochemical characteristic parameters of the battery cell, such as internal resistance, capacity, and formation rate of solid-state electrolyte interface film, with its initial value or historical benchmark value, and quantifying the deviation degree combined with the historical operation data (such as high cycle number, long time high temperature operation, etc.). For example, significant increase in internal resistance or significant capacity degradation can be considered as drift. Predicting the sensitivity change trend of each single battery cell to instantaneous current fluctuation within a preset time window refers to using a machine learning model or an empirical model to predict whether the response characteristics of the battery cell to current fluctuation will tend to be sensitive in the future (for example, in the next 100 cycles or 1000 hours), such as being more prone to voltage spikes or being more sensitive to bypass current adjustment, based on historical operation data and drift degree.

[0150] In practical application, dynamically updating the current fluctuation response threshold corresponding to each single battery cell according to the drift degree and the sensitivity change trend refers to adjusting the threshold for limiting the peak value and duration of instantaneous current fluctuation in real time according to the aging state of the battery cell and the sensitivity prediction result. For example, for a battery cell with high aging degree or predicted increased sensitivity, the current fluctuation response threshold is tightened so that it triggers adjustment under smaller fluctuation. And / or correcting the initial setting value of the establishment slope of the bypass current refers to adjusting the increase speed of the bypass current in the initial establishment stage according to the current state and prediction trend of the battery cell, for example, reducing the initial setting value of the establishment slope for a battery cell with high sensitivity to reduce the initial impact. And / or correcting the initial setting value of the conduction duration of the power switching element in the bypass current channel refers to adjusting the initial conduction time of the power switching element in each switching section to more finely control the duration of the bypass current.

[0151] Thus, when the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, the first adjustment is performed based on the corrected initial setting value of the establishment slope and / or the corrected initial setting value of the conduction duration, that is, the first adjustment starts from the dynamically evaluated parameters instead of using static initial setting values, so that the adjustment is more suitable for the actual operating state and aging degree of the battery cell.

[0152] The scheme of the present application evaluates the drift degree of the electrochemical characteristic parameters and predicts the trend of the sensitivity change to the instantaneous current fluctuation by introducing historical operating data and combining the current electrochemical characteristic parameters, so that the current fluctuation response threshold, the initial setting value of the establishment slope of the bypass current, and the initial setting value of the conduction duration of the power switching element can be dynamically updated and corrected, avoiding the mismatch of the threshold or improper adjustment of the parameters due to the aging of the battery cell; when the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, the first adjustment is performed based on the corrected initial setting value, which can make the response of the bypass balancing operation more accurate and efficient, and continuously suppress the transient voltage peak.

[0153] In some preferred embodiments, assuming that during the formation and capacity test of a lithium battery pack, the internal resistance of a certain single battery cell increases by 20% compared to the initial value after 500 charge and discharge cycles and 1000 hours of cumulative work, and the temperature change record of the battery cell shows that the battery cell has been in a high temperature environment for a long time. First, the system will obtain the historical operating data of the single battery cell, such as the number of charge and discharge cycles, the cumulative working time, and the temperature change record. Second, according to the current electrochemical characteristic parameters (such as internal resistance and capacity) and these historical operating data, the system evaluates that the electrochemical characteristic parameters of the single battery cell have obvious drift, and predicts that its sensitivity to the instantaneous current fluctuation will further increase in the next 100 cycles. Based on the drift degree and the trend of the sensitivity change, the system will dynamically update the current fluctuation response threshold of the single battery cell, for example, reduce the peak threshold from 50 mA to 40 mA, and shorten the duration threshold from 100 us to 80 us. At the same time, the system will also correct the initial setting value of the establishment slope of the bypass current, so that it is more gentle when establishing the bypass current channel, for example, adjust the initial slope from 1 A / ms to 0.8 A / ms. When the instantaneous current fluctuation is detected in the bypass current channel of the single battery cell in the subsequent test, and its peak reaches 45 mA (exceeding the updated 40 mA threshold), the system will perform the first adjustment based on the corrected 0.8 A / ms establishment slope, instead of using the original 1 A / ms slope. This pre-adjustment based on historical data and prediction enables the bypass balancing operation to respond to the actual state of the battery cell earlier and more accurately, thereby more effectively suppressing the transient voltage peak and avoiding damage to the battery cell.

[0154] In another embodiment of the present application, it is further proposed to modify the initial setting value of the establishment slope of the bypass current, and the specific steps include:

[0155] S3343-1: Obtain the formation stage information of each single battery cell, which includes the current state of charge of the single battery cell and the thickness of the formed solid electrolyte interface film;

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

[0157] S3343-3: According to the nonlinear slope adjustment curve, determine the target change rule of the bypass current change speed with time during the establishment of the bypass current channel, and generate an adjustment amount for modifying the establishment slope of the bypass current according to the target change rule;

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

[0159] Specifically, the formation stage information refers to the relevant data of the electrochemical activation process experienced by the single battery cell in the first charging cycle in the production process of the lithium battery, which is used to understand and predict the behavior of the battery cell in the bypass equalization operation. Among them, the current state of charge (State of Charge, SOC) of the single battery cell reflects the available energy of the active material inside the battery cell, which will affect the response speed of the battery cell to current change and internal impedance; the thickness of the formed solid electrolyte interface film (Solid Electrolyte Interphase, SEI) is a key indicator of the formation process, and the formation and stability of SEI film have a significant impact on the cycle life and safety of the battery cell. SEI film of different thickness will change the interface impedance and ion transport characteristics of the battery cell, and then affect the transient response of the bypass current establishment.

[0160] The nonlinear slope adjustment curve set is a set of curves designed in advance or obtained through experimental data and simulation models, and each curve represents an ideal or optimized rule of the change of the bypass current change speed with time under a certain state of the battery cell; these curves can be polynomial functions, exponential functions or other nonlinear functions, which aim to more finely control the rising or falling process of the current to adapt to the electrochemical characteristics of the battery cell in different formation stages. By combining the formation stage information, the drift degree and the sensitivity change trend, the nonlinear slope adjustment curve that best matches the current state of the single battery cell can be selected from the set. For example, for a battery cell with a thin SEI film and low internal resistance, a curve with a slow initial slope and gradually accelerating later can be selected to avoid impacting the newly formed SEI film; while for a battery cell with a stable SEI film and high internal resistance, a curve with a smoother overall slope can be selected.

[0161] According to the selected nonlinear slope adjustment curve, a target variation rule of the bypass current change speed with time during the bypass current channel establishment can be determined, which is no longer a simple linear slope but dynamically changes with time to match the transient response characteristics of the battery cell; based on the target variation rule, an adjustment amount for correcting the establishment slope of the bypass current is generated, which can be an increment or a decrement relative to the initial set value or a new slope parameter directly specified, and finally the initial set value of the establishment slope of the bypass current is corrected according to the adjustment amount, so that the establishment process of the bypass current is more refined and adaptive.

[0162] The scheme of the present application more comprehensively evaluates the real-time state of the single battery cell by introducing the formation stage information of the single battery cell and combining the drift degree of the electrochemical characteristic parameter and the sensitivity change trend to instantaneous current fluctuation; compared with the slope correction method relying only on the general parameter or the linear model, based on the current state of charge and the thickness of the formed solid electrolyte interface film and other formation stage information, the bearing capacity of the battery cell to the current impact can be more accurately described, and a matching curve is selected from the preset set of nonlinear slope adjustment curves, so that the establishment slope of the bypass current can dynamically change according to the nonlinear rule in the initial stage, the middle stage and the stage close to the target current.

[0163] For example, when the battery cell is more sensitive to current change at the initial stage of SEI film formation, a curve with a smaller initial slope can be selected to avoid excessive current impact leading to SEI film rupture or uneven growth; after the SEI film is stable, the slope can be appropriately increased to speed up the balancing speed. Thus, the correction of the establishment slope of the bypass current is transformed from a "fixed value or simple adjustment value" to a nonlinear optimization based on the "personalized" state of the battery cell, so as to more specifically reduce the transient voltage spikes caused by the interaction of the bypass current rapid switching and the parasitic inductance, especially suitable for the formation stage of the battery cell state sensitive.

[0164] In some preferred embodiments, the following is described by a specific example:

[0165] Assuming that during the lithium battery formation and capacity test process, a certain single battery A is identified as a target single battery that needs to be bypassed for equalization operation. When modifying the slope of the bypass current establishment, first obtain the formation stage information of the single battery A. Specifically, through the battery management system (BMS) or a dedicated sensor, it is obtained that the current state of charge of the single battery A is 80%, and the thickness of the formed solid-state electrolyte interface film is 50 nanometers; at the same time, combined with historical operation data and evaluation of electrochemical characteristic parameters, it is determined that the internal resistance drift degree of the single battery A is moderate, and the sensitivity change trend to instantaneous current fluctuation is gradually decreasing. Based on this information, the system will match and select from a set of pre-set nonlinear slope adjustment curves, for example, the set contains curves designed for different stages such as "SEI film formation initial stage", "SEI film stable period" and "SEI film aging period"; according to the state of charge, SEI film thickness, drift degree and sensitivity of the single battery A, the system selects a "SEI film stable period moderate sensitivity" nonlinear slope adjustment curve, which has a relatively flat slope in the initial stage of bypass current establishment, and then the slope gradually increases, and the slope again slows down when approaching the target current. According to the curve, the system calculates the target change rule of the bypass current change speed with time during the bypass current channel establishment, for example, the bypass current rises at a speed of 50mA / ms in the first 100 milliseconds, rises at a speed of 100mA / ms in the next 200 milliseconds, and then rises smoothly at a speed of 20mA / ms before reaching the target current; According to this, the adjustment amount for modifying the establishment slope of the bypass current is generated, for example, the initial setting value is 70mA / ms, and the average target slope calculated according to the curve is 80mA / ms, so the adjustment amount is +10mA / ms, and finally the initial setting value of the establishment slope of the bypass current 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 protecting the battery while achieving efficient and accurate current control.

[0166] Reference Figure 2 The present application proposes a lithium battery formation and capacity test health monitoring and performance diagnosis system, which comprises:

[0167] A voltage data acquisition module 1 is used to acquire voltage data of each single battery in the battery pack, and to identify target single batteries that need to be bypassed for equalization operation according to the voltage data;

[0168] The bypass channel establishment module 2 is configured to, in response to identifying the target single battery cell, perform a bypass equalization operation: gradually establishing a bypass current channel for the target single battery cell at a preset bypass current change rate, so that the bypass current gradually increases from zero or an initial value at the bypass current change rate, to suppress transient voltage spikes caused by the interaction of parasitic inductance in the battery pack internal connection wires and the test system lines and the rapid switching of the current;

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

[0170] The bypass channel revocation module 4 is configured to, at the end of the bypass equalization operation, gradually decrease the bypass current until the bypass current channel is removed at the corrected bypass current change rate, and the bypass current change rate in the bypass current gradual decrease process does not exceed the bypass current change rate safety threshold.

[0171] The present application forms a system that works cooperatively by modularizing the health monitoring and performance diagnosis function modules in the lithium battery formation and capacity grading test.

[0172] The above only describes the embodiments of the present application and is not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for health monitoring and performance diagnosis of lithium battery formation and capacity test, characterized in that, The method comprises: acquiring voltage data of each single battery cell in the battery pack, and identifying a target single battery cell requiring bypass equalization operation according to the voltage data; in response to identifying the target single battery cell, performing bypass equalization operation: gradually establishing a bypass current channel for the target single battery cell at a preset bypass current change rate, and gradually increasing the bypass current from zero or an initial value at the bypass current change rate, so as to suppress transient voltage spikes caused by the interaction of parasitic inductance in the internal connection wire of the battery pack and the test system line and the rapid switching of current; during the establishment of the bypass current channel, real-time acquisition of current change data in the bypass current channel, and adjustment of the establishment slope and / or segmented switching timing of the bypass current according to the current change data, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, to correct the bypass current change rate; at the end of the bypass equalization operation, gradually reducing the bypass current until the bypass current channel is removed at the corrected bypass current change rate, and the bypass current change rate in the gradual reduction process of the bypass current does not exceed the bypass current change rate safety threshold.

2. The lithium battery formation and grading test health monitoring and performance diagnosis method of claim 1, wherein, According to the current change data, adjust the establishment slope and / or segmented switching timing of the bypass current, so that the bypass current change rate does not exceed the preset bypass current change rate safety threshold, comprising: acquiring voltage data of each single battery cell; generating a charging current adjustment instruction corresponding to each single battery cell according to the voltage data; gradually reducing the charging current applied to the target single battery cell at a preset charging current change rate, and adjusting the establishment slope and / or segmented switching timing of the bypass current in combination with the current change data during the gradual reduction of the charging current of the target single battery cell, so that the bypass current change rate meets the bypass current change rate safety threshold while reducing the transient fluctuation caused by the interaction of the switching edge of the bypass current channel and the parasitic inductance, to suppress the superimposed fluctuation component of the transient voltage spikes. 3.The lithium battery formation and grading test health monitoring and performance diagnosis method of claim 1, wherein, The method further comprises: during the bypass equalization operation, acquiring a voltage change rate signal across the power switching element in the bypass current channel, and determining deviation data of the switching transition characteristics of the power switching element relative to the preset characteristics according to the voltage change rate signal; obtaining performance drift data of the power switching element according to the deviation data; adaptively adjusting the driving signal parameters of the power switching element according to the deviation data to compensate for the performance drift of the power switching element; correcting the segmented switching timing of the bypass current channel according to the deviation data and the driving signal parameters; recording the performance drift data, and updating the adaptive adjustment strategy and / or outputting maintenance warning information based on the performance drift data.

4. The lithium battery formation and test health monitoring and performance diagnosis method of claim 1, wherein, Real-time acquisition of current change data in the bypass current channel, and adjustment of the establishment slope and / or segmented switching timing of the bypass current according to the current change data, comprising: During the bypass current channel establishment, the current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain the current change data, and transient current fluctuation data reflecting transient current fluctuation in the bypass current channel is obtained by extracting transient components from the current change data; The transient current fluctuation data is processed to identify transient current fluctuation information; The establishment slope of the bypass current is adjusted based on the transient current fluctuation information, and / or the segmented switching timing of the bypass current is adjusted.

5. The lithium battery formation and test health monitoring and performance diagnosis method of claim 4, wherein, The current in the bypass current channel is sampled at a preset high-frequency sampling frequency to obtain the current change data, and transient current fluctuation data reflecting transient current fluctuation in the bypass current channel is obtained by extracting transient components from the current change data, comprising: Parallel sampling of the current in the bypass current channel is performed through multiple independent sampling channels at the high-frequency sampling frequency to obtain current change data corresponding to each sampling channel, respectively; Transient current fluctuation data corresponding to each sampling channel is obtained by extracting transient components from the current change data corresponding to each sampling channel, respectively; Real-time data consistency verification is performed on the transient current fluctuation data obtained by multiple independent sampling channels in parallel to identify and eliminate abnormal data to obtain verified transient current fluctuation data; Adaptive filtering is applied to the verified transient current fluctuation data to suppress noise to obtain filtered transient current fluctuation data; A reference signal is periodically input to multiple sampling channels, and the performance drift of multiple sampling channels is evaluated according to the response of multiple sampling channels to the reference signal to generate calibration parameters; The filtered transient current fluctuation data is corrected according to the calibration parameters to obtain corrected transient current fluctuation data.

6. The lithium battery formation and test health monitoring and performance diagnosis method of claim 4, wherein, The establishment slope of the bypass current is adjusted based on the transient current fluctuation information, and / or the segmented switching timing of the bypass current is adjusted, comprising: Obtain the electrochemical characteristic parameters of each single battery, the electrochemical characteristic parameters include internal resistance, capacity and formation rate of solid electrolyte interface film; According to the electrochemical characteristic parameters, the current fluctuation response threshold value of each single battery is established respectively, the current fluctuation response threshold value includes peak threshold value and duration threshold value, wherein the peak threshold value is used to limit the peak value of the transient current fluctuation, and the duration threshold value is used to limit the duration of the transient current fluctuation; The establishment process of the bypass current channel is divided into multiple switching segments, and switching interval time and switching segment duration are set for each switching segment, thereby forming the segmented switching timing; When the transient current fluctuation information indicates that the transient current fluctuation in the bypass current channel corresponding to any single battery exceeds its corresponding current fluctuation response threshold value, the establishment slope of the bypass current corresponding to the single battery and / or the segmented switching timing is adjusted for the first time: in response to the peak value of the instantaneous current fluctuation exceeding the peak value threshold, performing adjustment of the build-up slope of the bypass current according to the formation rate of the solid-state electrolyte interface film; in response to the duration of the instantaneous current fluctuation exceeding the duration threshold, performing adjustment of the on duration of the power switching element in the bypass current channel according to the internal resistance and capacity, and adjusting the duration of each switching segment and / or the switching interval time in the segmented switching timing accordingly to control the duration of the bypass current, so that the instantaneous current fluctuation falls within the current fluctuation response threshold, and the change rate of the bypass current does not exceed the bypass current change rate safety threshold.

7. The lithium battery formation and test health monitoring and performance diagnosis method of claim 1, wherein, According to the current change data, adjusting the build-up slope of the bypass current and / or the segmented switching timing, further comprising: generating an adjustment instruction for indicating adjustment of the build-up slope of the bypass current and / or the segmented switching timing, and the adjustment instruction containing timestamp information and check code information; sending the adjustment instruction to an execution end of the bypass current channel corresponding to the target single battery cell; after the execution end receives the adjustment instruction, checking the adjustment instruction according to the check code information; when the check is passed, judging the timeliness of the adjustment instruction according to the timestamp information, and executing or discarding the adjustment instruction in response to the timeliness of the adjustment instruction; receiving execution state feedback information output by the execution end after executing the adjustment instruction, judging the execution of the adjustment instruction according to the execution state feedback information, and re-sending adjustment instructions and / or adjusting subsequent adjustment strategies in response to the execution. 8.The lithium battery formation and grading test health monitoring and performance diagnosis method of claim 6, wherein, Before the first adjustment, further comprising: obtaining historical running data of each single battery cell, the historical running data including the number of charge and discharge cycles, the cumulative working time and the temperature change record; according to the current electrochemical characteristic parameter and the historical running data, evaluating the drift degree of the electrochemical characteristic parameter of each single battery cell, and predicting the sensitivity change trend of each single battery cell to the instantaneous current fluctuation within a preset time window; according to the drift degree and the sensitivity change trend, dynamically updating the current fluctuation response threshold corresponding to each single battery cell, and / or correcting the initial setting value of the build-up slope of the bypass current, and / or correcting the initial setting value of the on duration of the power switching element in the bypass current channel; and when the instantaneous current fluctuation information indicates that the instantaneous current fluctuation exceeds the updated current fluctuation response threshold, performing the first adjustment based on the corrected initial setting value of the build-up slope and / or the corrected initial setting value of the on duration. 9.The lithium battery formation and grading test health monitoring and performance diagnosis method of claim 8, wherein, correcting the initial setting value of the build-up slope of the bypass current, comprising: obtaining formation stage information of each single battery cell, the formation stage information including the current state of charge of the single battery cell and the thickness of the formed solid-state electrolyte interface film; According to the formation stage information, the drift degree and the sensitivity change trend, a nonlinear slope adjustment curve matched with the monomer battery cell state is selected from a preset nonlinear slope adjustment curve set; According to the nonlinear slope adjustment curve, a target change rule of the bypass current change speed with time during the bypass current channel establishment is determined, and an adjustment amount for correcting the establishment slope of the bypass current is generated according to the target change rule; The initial setting value of the establishment slope of the bypass current is corrected according to the adjustment amount.

10. A lithium battery formation and capacity test health monitoring and performance diagnosis system, characterized in that, Comprise: A voltage data acquisition module is configured to acquire voltage data of each monomer battery cell in a battery pack, and identify a target monomer battery cell requiring bypass equalization operation according to the voltage data; A bypass channel establishment module is configured to, in response to identifying the target monomer battery cell, perform bypass equalization operation: gradually establish a bypass current channel for the target monomer battery cell at a preset bypass current change speed, and gradually increase the bypass current from zero or an initial value at the bypass current change speed, so as to suppress transient voltage spikes caused by the interaction of parasitic inductance in the internal connection wire of the battery pack and the test system line and the rapid switching of current; A current data acquisition module is configured 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 timing according to the current change data, so that the bypass current change speed does not exceed a preset bypass current change rate safety threshold, to correct the bypass current change speed; A bypass channel revocation module is configured to, when the bypass equalization operation ends, gradually decrease the bypass current at the corrected bypass current change speed until the bypass current channel is removed, and make the bypass current change speed in the gradual decrease process of the bypass current not exceed the bypass current change rate safety threshold.

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