Battery maintenance method, system, and medium

Abstract

The application provides a battery maintenance method, system and medium. The method comprises: acquiring battery data of a battery management system and performing an electrochemical impedance spectrum scan; estimating an SOH value of the battery based on the battery data and the impedance spectrum scan result; adaptively setting a frequency and a duty cycle of a pulse current used for maintenance based on the SOH value and a battery temperature; and applying a high-frequency pulse current to the battery based on the set frequency and duty cycle, and maintaining the battery according to a multi-stage charging and discharging protocol. The embodiments of the application can improve the service life and safety of new energy batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery maintenance, in particular to a battery maintenance method, system and medium. BACKGROUND

[0002] In the entire life cycle of new energy batteries, they frequently experience harsh working conditions such as rapid charging, deep discharging and high temperature operation; which leads to a series of irreversible aging phenomena inside the battery: electrode polarization increases; solid electrolyte interface film (SEI film) continuously thickens, breaks and regenerates; lithium dendrite growth, which may cause the puncture of the separator and trigger internal short circuit; lithium ion migration efficiency decreases; and finally the gradual decay of the reversible capacity of the battery.

[0003] At present, the mainstream battery maintenance technology mainly relies on traditional constant current or constant voltage charging and discharging strategies. These strategies are static and extensive, lacking real-time response to changes in core state parameters inside the battery (such as internal resistance, charge transfer impedance), and thus cannot specifically repair the polarization phenomena, ion migration channel aging and lithium dendrite growth inside the battery, etc. The maintenance effect is very limited, and it cannot automatically adapt to the battery state and environmental temperature. In addition, most of the existing maintenance equipment do not have composite control capabilities such as high-frequency pulse modulation, intelligent temperature control, adaptive power regulation, etc., making it difficult to meet the differentiated and refined maintenance needs of complex application environments (such as high and low temperatures, vibration) and diverse battery systems (such as NMC ternary lithium, LFP lithium iron phosphate, LCO lithium cobaltate, etc.). SUMMARY

[0004] The purpose of the present application is to provide a battery maintenance method, system and medium, which can improve the service life and safety of new energy batteries.

[0005] To solve the above technical problems, the present application provides a battery maintenance method, which comprises:

[0006] acquiring battery data of a battery management system and performing electrochemical impedance spectroscopy scanning; estimating the SOH value of the battery based on the battery data and the impedance spectroscopy scanning result; and adaptively setting the frequency and duty cycle of the pulse current used for maintenance based on the SOH value and the battery temperature and duty cycle ; applying high-frequency pulse current to the battery based on the set frequency and duty cycle , and maintaining the battery according to a multi-stage charging and discharging protocol.

[0007] The second aspect of the present application provides a battery maintenance system applied to the above-mentioned battery maintenance method, which comprises: a communication module configured to perform bidirectional data interaction with a battery management system; a data acquisition module configured to acquire battery data of the battery management system and perform electrochemical impedance spectroscopy scanning; a main

[0008] The control unit is connected to the communication module and the data acquisition module, configured to estimate the SOH value of the battery based on the battery data and the impedance spectrum scanning result, and set the frequency of the pulse current used for maintenance based on the SOH value and the battery temperature and duty cycle , generate a PWM control signal based on the frequency and duty cycle , and perform maintenance on the battery according to a multi-stage charge-discharge protocol; the power conversion module is connected to the control unit and configured to convert the input alternating current into direct current; the pulse current driving module is connected to the control unit and the power conversion module, and configured to modulate the direct current into high-frequency square-wave pulse current based on the PWM control signal and output to the battery.

[0009] The third aspect of the embodiment of the present application provides a computer storage medium. A computer program is stored on the computer storage medium, and the computer program is executed by a processor to implement the steps of the battery maintenance method.

[0010] Compared with the prior art, the embodiment of the present application realizes accurate estimation of the internal health state (SOH) of the battery by fusing battery management system (BMS) data and electrochemical impedance spectrum (EIS) scanning, breaks the traditional “one-size-fits-all” maintenance mode, and provides a tailor-made maintenance solution for each battery. The use of high-frequency pulse current with adjustable frequency and duty cycle can effectively suppress electrode polarization, improve ion migration efficiency, and has a positive effect on SEI film repair and lithium dendrite inhibition, thereby delaying battery degradation from a mechanism. In addition, the maintenance parameters (f, D) of the embodiment of the present application can be adjusted in real time according to the SOH and temperature, and convergence judgment is performed based on the improvement rate of charge transfer resistance during the maintenance process, thereby realizing closed-loop control and dynamic optimization of the maintenance process and maximizing the maintenance effect. 、 BRIEF DESCRIPTION OF DRAWINGS

[0011] One or more embodiments are illustrated by way of example in the figures that are part of this disclosure and which are illustrative, but not restrictive, of the embodiments, wherein elements having the same reference numbers designate corresponding elements and wherein the figures do not necessarily bear a proportional relationship to each other. The figures are not necessarily to scale.

[0012] Figure 1 is a flowchart of a battery maintenance method according to an embodiment of the present application;

[0013] Figure 2 is a flowchart of setting the frequency of the pulse current used for maintenance according to an embodiment of the present application;

[0014] ​Figure 3 is a flowchart of setting a duty cycle of a pulse current for battery maintenance according to an embodiment of the present application;

[0015] Figure 4 is a structural diagram of a battery maintenance system according to an embodiment of the present application;

[0016] Figure 5 is a structural diagram of a battery maintenance system according to another embodiment of the present application. DETAILED DESCRIPTION

[0017] The forgoing detailed description of the application has been presented for the purposes of elucidation and will not limit the application as construed. It is intended that the description serve only as a possible interpretation. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus described and illustrated herein without departing from the spirit and scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0018] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is to be understood that the terms "approximately" and "substantially" are used herein to represent values that are close to, but not necessarily exactly, the stated value. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It will be understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0019] It is also to be understood that the above description is one possible implementation of the application, and that many modifications, variations and alternatives can be made to the described implementation without departing from the spirit or scope of the application. It is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents. It is to be understood that the drawing and descriptions herein are by way of example only, in which:

[0020] Further, in the following description, numerous specific details are provided for a thorough understanding of the examples. One skilled in the relevant art will recognize, however, that the application can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth.

[0021] Based on this, the embodiment of the application provides a battery maintenance method, such as Figure 1 As shown in the following steps:

[0022] In step 101, the battery data of the battery management system is acquired, and an electrochemical impedance spectrum scan is performed.

[0023] In the embodiment of the application, the battery management system (BMS) data can be acquired through the CAN bus. For example, a MCP2562 CAN transceiver is used to establish a communication connection with the BMS of the vehicle or the battery pack, and the battery data is periodically read, which includes but is not limited to the following parameters: single cell / pack voltage U, current I, battery state of charge SOC, battery temperature , inter-cell consistency (maximum / minimum single cell voltage difference ), cycle number N, historical alarm records (including overvoltage, overcurrent, overtemperature and other abnormal events), and BMS set upper limit voltage , upper limit temperature , and other permitted threshold values. When the communication is abnormal or the permission is insufficient, a local degraded mode (such as relying on an instrument) can also be entered for sampling.

[0024] At the same time, when the battery state of charge SOC and the temperature are within the permitted window (for example, SOC is 40%-70%, 0℃≤temperature ≤45℃), an electrochemical impedance spectrum (EIS) scan is performed on the battery pack or the segmented subsystem. Specifically, a small amplitude alternating current excitation with an amplitude of 10-100 mA rms is applied to avoid disturbing the SOC, the frequency is swept point by point in the frequency range of 0.1 Hz to 1000 Hz, the same frequency voltage response is collected, and the complex impedance is calculated. Subsequently, the impedance spectrum is fitted using the Randles equivalent circuit model to obtain electrochemical parameters, including: solution resistance (electrolyte and conductor ohmic resistance), charge transfer resistance (resistance of electrode / electrolyte interface reaction rate), double-layer capacitance (double-layer capacitance formed on the electrode surface), and Warburg diffusion parameter (describing the impedance characteristics caused by the diffusion of substances in the electrode).

[0025] In step 102, the health degree SOH value of the battery is estimated based on the battery data and the impedance spectrum scan result.

[0026] In an optional embodiment, the SOH value of the battery can be estimated by combining the impedance spectrum scan (EIS) characteristic parameters and the historical data of the battery management system (BMS) using formula (1):

[0027] (1)

[0028] wherein, represents the effective capacity estimated by the near-periodic coulomb integral or the charge-discharge record, is the rated capacity of the new battery, represents the high-frequency resistance and the charge transfer resistance the equivalent impedance calculated comprehensively, is the initial impedance reference value of the new battery, is the calibration weight factor, which can be calibrated by experiments. The model comprehensively considers the two core aging factors of capacity attenuation and impedance growth.

[0029] In another optional embodiment, the SOH value of the battery can be estimated by formula (2):

[0030] (2)

[0031] wherein, represents the charge transfer resistance fitted by the impedance spectrum scan, represents the initial charge transfer resistance of the new battery, represents the solution resistance fitted by the impedance spectrum scan, represents the solution resistance of the new battery, , is the calibration weight factor, , which can be calibrated by experiments. The model directly uses the change rate of the EIS characteristic parameter to reflect the health state, and the response is more direct.

[0032] In step 103, based on the SOH value and the battery temperature, the frequency and the duty cycle of the pulse current used for maintenance are adaptively set.

[0033] Specifically, in the embodiments of the present application, the method for setting the frequency of the pulse current used for maintenance based on the battery health degree (SOH) value and the battery temperature can refer to Figure 2 , and is specifically as follows:

[0034] In step 1031, the impedance spectrum scan result is fitted based on an equivalent circuit model (such as Randles model) to obtain the charge transfer resistance (unit Ω, reflecting the interface reaction rate) and the double-layer capacitance (unit F, reflecting the energy storage capacity of the electrode surface).

[0035] In step 1032, the charge transfer resistance and the double-layer capacitance The theoretical optimal frequency is calculated The optimal frequency The calculation formula is as follows:

[0036]

[0037] To make up for the difference between the theoretical model and the actual interface reaction, and improve the applicability, a correction coefficient Based on the correction coefficient The theoretical optimal frequency is corrected to further obtain a corrected frequency Make it close to the characteristic frequency of the electrochemical process, and the corrected frequency Can be expressed as:

[0038]

[0039] The range is a reasonable value range determined by statistical analysis of the impedance spectrum characteristic points of various system batteries (including NMC, NCA, LFP, etc.). This range can take into account the dynamic response characteristics of different chemical systems and different health and temperature conditions, which can ensure the activation effect and avoid excessive polarization and side reactions.

[0040] The specific value of

[0041] Table 1:

[0042]

[0043] As the health SOH decreases, the electrode / electrolyte interface film thickens, the charge transfer impedance rises, and the double-layer capacitance decreases, resulting in a decrease in the characteristic frequency, so Should be reduced with the decrease of SOH.

[0044] Temperature rise can promote ion migration and reaction kinetics process, allowing higher excitation frequency; when the temperature is too low, ion diffusion is limited, and Should be reduced to suppress polarization and thermal stress.

[0045] In addition, The value of is also related to the difference between the system, such as: the reaction rate of NMC / NCA ternary system is higher, and =0.18-0.20 is recommended; the kinetics of LFP system is relatively slow, and =0.15-0.18 is recommended.

[0046] During the system operation, the control unit can automatically adjust the frequency according to the real-time detection of SOH, temperature and impedance changes . For example, when the temperature drops or SOH decreases, the system automatically reduces the upper limit value ; when the temperature rises or the state recovers, gradually restore to the default upper limit value. Through this dynamic adjustment mechanism, adaptive control of pulse frequency can be realized, so that the maintenance process is always in the best excitation interval.

[0047] In step 1033, the frequency amplification coefficient is determined based on the SOH value , and the temperature compensation coefficient is obtained based on the battery temperature and the ambient temperature. Specifically, in this step, the frequency amplification coefficient can be adjusted according to the battery health SOH The determination method of the frequency amplification coefficient

[0048] When SOH>90%, = 1.0;

[0049] When 70% ≤ SOH ≤ 90%, = 1.2;

[0050] When SOH<70%, = 0.8

[0051] In this embodiment, the temperature compensation coefficient is obtained based on the battery temperature and the ambient temperature. First, the corrected temperature can be defined according to the battery temperature and the ambient temperature , = , and then the compensation coefficient is calculated according to the corrected temperature , , .

[0052] In step 1034, the theoretical optimal frequency is adjusted based on the frequency amplification coefficient and the temperature compensation coefficient to obtain a target frequency, and the target frequency is limited within a preset frequency range to obtain the frequency .

[0053] Preferably, in this embodiment, the target frequency can also be the frequency obtained by adjusting the corrected frequency based on the frequency amplification coefficient and the temperature compensation coefficient, and the target frequency is limited within a preset frequency range to obtain the frequency : . Wherein can take a value of 100 Hz, It can be set to 2000 Hz.

[0054] Additionally, in this embodiment of the application, when the temperature is corrected... Hardware limiting can be performed at that time. =500Hz.

[0055] In this embodiment, the duty cycle of the maintenance pulse current is set based on the SOH value and battery temperature. The method can be referred to Figure 3 The details are as follows:

[0056] In step 1036, the initial duty cycle is calculated based on the battery temperature and ambient temperature. Specifically, this can be done by first calculating the battery temperature... and ambient temperature Define correction temperature , = Initial duty cycle It can be represented as: .in: The baseline duty cycle (e.g., 50%). This is the temperature regulation coefficient, expressed in % / °C (e.g., 0.33), which can be calibrated experimentally. Battery temperature; The ambient temperature (e.g., 25°C).

[0057] In step 1037, the thermal constraint duty cycle is calculated based on the allowable heat dissipation power predicted by the thermal model or measured by actual measurements, the bus voltage, and the pulse peak current. ;

[0058] in: Permissible heat dissipation power (in W) predicted by thermal models or measured in actual measurements; Bus voltage (in V); This is the peak pulse current (in amperes).

[0059] In step 1038, the smaller value between the initial duty cycle and the thermal constraint duty cycle is taken, and the smaller value is limited to a preset duty cycle range to obtain the duty cycle. Duty cycle It can be represented as: .in This represents a limiting function that constrains the duty cycle within an effective and safe range of 20% to 80%. When the percentage is less than 20%, the waveform is invalid and cannot form a valid pulse; while When the current is greater than 80%, it approaches constant current, loses the intermittent activation effect, and may overheat.

[0060] At the same time of duty cycle adjustment, the system can also implement limiting amplitude on peak current, average current and voltage upper limit respectively, such as:

[0061]

[0062] Wherein: is the average current; is the battery rated current; is the pulse peak current; is the pulse limit current that the battery can withstand; is the single battery voltage; is the single battery voltage provided by the BMS.

[0063] When any of the proximity thresholds triggers a warning, the duty cycle can be lowered in turn according to priority Or lower the frequency Or enter the cooling delay.

[0064] In step 104, based on the set frequency And the duty cycle , high-frequency pulse current is applied to the battery, and the battery is maintained according to the multi-stage charging and discharging protocol.

[0065] Specifically, the multi-stage charging and discharging protocol of the embodiment of the application includes:

[0066] In the first stage of the battery state of charge of 0% to 80%, constant current charging is carried out by using high-frequency pulse current; in the second stage of the battery state of charge of 80% to 100%, constant voltage control is superimposed while charging by using high-frequency pulse current, so that the single battery voltage does not exceed the upper limit voltage given by the battery management system; in the third stage of the battery state of discharge of 100% to 20%, constant current discharge is carried out by using low-frequency pulse current.

[0067] In the first stage (SoC 0%–80%), constant current charging is carried out by using high-frequency pulse current in this stage: output square wave pulse at (The upper limit can be set to 2000 Hz) High-frequency pulse helps to reduce interface polarization (i.e. Transient response) and improve lithium ion migration rate, making the embedding process more uniform. 2000Hz is an empirical preferred value, which can also be fine-tuned in the range of [1000z–2000Hz]. Current amplitude range [0.01C–3C] (dynamically limited according to BMS allowed value and heat dissipation capacity), “C rate” is defined as: Wherein is the battery nominal capacity (Ah), converted to amperes. 0.01C: 100 hours of full current; 3C: 20 minutes of full current.

[0068] The duty cycle is adjusted according to Execute [20% - 80%] low duty cycle → intermittent current, conducive to heat diffusion; high duty cycle → large average current, fast charging; adaptive adjustment within the value range. Real-time monitoring of temperature and voltage, if or the single cell voltage is close to , first reduce the duty cycle, then reduce the frequency, and if necessary, insert a cooling interval (duty cycle 0%, duration 10-60s). For example: perform incremental capacity analysis (ICA) every 30 seconds to monitor the anode lithium extraction characteristic peak: if the voltage platform characteristic peak is detected: reduce the duty cycle by 10% and increase the pulse frequency to 2500Hz.

[0069] Stop condition (any one satisfies): SoC ≥ 80%, any single cell voltage difference > 50mV, cumulative charging time > 60min.

[0070] In the second stage (SoC 80% - 100%), pulse + constant voltage compensation is used in this stage: maintain pulse maintenance (high frequency is conducive to interface update and polarization release), superimpose constant voltage control loop, so that the single cell voltage does not exceed the given by BMS (such as NMC 4.20 V ± 0.03 V, LFP 3.65 V ± 0.03 V). Voltage loop and pulse loop coordination: when the voltage approaches the upper limit ( , preferentially reduce to the lower limit, still over the limit, reduce or turn into trickle maintenance (duty cycle ≤ 20%). In this stage, the pulse frequency: , maintain high-frequency pulse, maintain electrode interface activity, reduce concentration polarization. Duty cycle 20% - 80% from the optimal value calculated in the parameter setting stage: voltage constraint U ≤ The system samples the single cell voltage in real time to prevent overcharging.

[0071] Constant voltage control: superimpose 4.20 ± 0.03V (use high-precision reference voltage source ADR4540).

[0072] Current decay law: linear or exponential decay with time t (minutes), the specific formula can be set to or other control strategies.

[0073] Special processing: when → 1 second of zero current relaxation period is inserted every 10 pulses, the temperature sampling frequency is increased to 1Hz.

[0074] Stopping condition (any one of the following conditions is met, the stage 2 is stopped): charging current ≤ 0.05C, cumulative time > 120min, SoC ≥ 95% and voltage is stable (ΔV < 1mV / 10s).

[0075] Stage switching rule: stage 2→ stage 3: SoC ≥ 95% or I ≤ 0.1C→ switch after 30s buffer.

[0076] In the third stage (SoC 100%-20%), pulse discharge shaping is used in this stage. Pulse discharge is performed at =100Hz, I=0.01C-0.5C constant current, which is used to activate the negative electrode and reduce the polarization residue at high SOC; when SoC drops to 20% or reaches the time, temperature rise or cycle upper limit, it is stopped. If necessary, coordinate with BMS equalization strategy (maintain consistency within the package). Duty cycle , ensure a minimum of 70%, maintain discharge energy continuity.

[0077] Safety mechanism:

[0078] Voltage protection: suspend discharge when single cell voltage ≤ 2.8V, continue after restoring to 3.0V.

[0079] Temperature compensation:

[0080] = Every 1℃ drop, duty cycle increases by 0.5%, ensuring energy output at low temperature.

[0081] Energy recovery:

[0082] Regenerative braking circuit is activated during pulse-off period, with a recovery efficiency ≥ 85%.

[0083] Stopping condition:

[0084] SoC ≤ 20%, voltage drop dV / dt > 50mV / s, cumulative time > 180min.

[0085] Stage switching rule:

[0086] Stage 3 termination: SoC ≤ 20% or dV / dt > 50mV / s → terminate immediately.

[0087] The stage conversion rule of the three stages is:

[0088] First stage→second stage: SoC ≥ 80% and ΔV < 1mV / 10s (switch immediately).

[0089] Second stage→third stage: SoC ≥ 95% or I ≤ 0.01C (switch after 30s buffer).

[0090] Phase 3 → Termination: SoC ≤ 20% or dV / dt > 50 mV / s.

[0091] In a preferred embodiment, after the battery is maintained according to the multi-stage charge-discharge protocol, further comprising: performing the electrochemical impedance spectrum scan again to obtain the charge transfer resistance after maintenance; calculating the change rate of the charge transfer resistance before and after maintenance; if the absolute value of the change rate is less than a preset threshold, determining that the maintenance converges and ending; otherwise, adjusting the frequency and duty cycle , and entering the next round of maintenance. Specifically, a rest / retest window (such as 5 minutes) can be set between the three-stage charge-discharge protocol, and the fast impedance spectrum scan (EIS) sampling is performed again (which can be shortened to the representative frequency point). The charge transfer resistance improvement rate (the change rate of the charge transfer resistance before and after maintenance) is used as the convergence index: if the absolute value of the change rate is less than a preset threshold (such as ), and the temperature rise benefit ratio is lower than the threshold, it is determined that the maintenance converges, the effect is significant, and the task ends. Otherwise, according to the "lighter not heavier" principle, the , frequency and duty cycle are adjusted slightly and the next round of short-period maintenance is entered.

[0092] The decision logic is as follows:

[0093] : continue maintenance of the parameters, : terminate maintenance, : reduce the frequency by 10%+duty cycle by 5%.

[0094] Termination conditions:

[0095] 2 consecutive periods , cumulative temperature rise per period, BMS reports cell imbalance .

[0096] In other embodiments, the number of iterations can also be set as a convergence condition, such as a maximum of iterations (such as ≤5), or a time length convergence condition (such as setting an upper limit of time length to end automatically).

[0097] Preferably, the embodiments of the application further include performing a safety check before entering substantive maintenance. For example, before obtaining the battery data of the battery management system, it is determined whether any of the following conditions exists: the single cell voltage exceeds the limit value, the voltage difference between the cells Exceeding the balance threshold, there is an insulation fault or high voltage relay is not closed, the battery temperature exceeds the permitted range, received BMS maintenance instructions prohibited; if any of the described cases, stop performing subsequent maintenance steps and sound and light warning and record fault code, ensure the safety of the operation.

[0098] Preferably, the embodiments of the application further comprise a three-level thermal protection mechanism, comprising:

[0099] Monitoring the temperature of the temperature monitoring point (such as IGBT junction temperature, electrolytic capacitor surface temperature, cooling liquid outlet temperature); when the temperature is greater than or equal to the first threshold and less than the second threshold, linearly reducing the duty cycle And selectively reducing the frequency ; When the temperature is greater than or equal to the second threshold and less than the third threshold, the upper limit of the frequency Is forced to be limited and the average output current is reduced; when the temperature is greater than or equal to the third threshold or the temperature sensor fails, the pulse current is turned off and the output is cut off; wherein the third threshold > second threshold > first threshold.

[0100] For example:

[0101] Primary (soft limit): when the temperature of the monitoring point T≥65℃ (first threshold), linearly reduce the duty cycle to 20%, and reduce the frequency by 20% if necessary.

[0102] Secondary (derating): T≥75℃ (second threshold), forced =500 Hz, the average current is reduced to 50% of the rated value.

[0103] Third (shutdown): T≥85℃ (third threshold) or any temperature sensor is lost / overrun, immediately turn off the PWM output, cut off the main contactor, and trigger the alarm.

[0104] In the embodiments of the application, any of the following situations immediately exits safely: BMS refuses, single overvoltage / undervoltage, overcurrent, insulation fault, emergency stop trigger, CAN heartbeat loss timeout. The exit process includes: current reduction → PWM off → high voltage off → fault code recording.

[0105] The embodiments of the application also include data recording and tracing: recording time stamps 、 , U / I / T, EIS characteristics, SOH curve and event code throughout the process, supporting local / upper computer export for life trend analysis and maintenance compliance proof.

[0106] This application's embodiments are compatible with the following battery systems: ternary lithium (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), and lithium titanate (LTO), etc. It supports a series cell count S=4–180, an operating voltage range of 12–800V, and features wide voltage identification capability and reverse connection protection mechanism.

[0107] Compared with the prior art, the embodiments of this application have the following advantages:

[0108] 1. Precise Diagnosis and Personalized Maintenance: By integrating battery management system (BMS) data and electrochemical impedance spectroscopy (EIS) scanning, the system can accurately estimate the state of health (SOH) of the battery, breaking away from the traditional "one-size-fits-all" maintenance model and providing a customized maintenance solution for each battery.

[0109] 2. Deep Repair and Performance Enhancement: The use of high-frequency pulsed current with adjustable frequency and duty cycle can effectively suppress electrode polarization, improve ion migration efficiency, and play a positive role in SEI film repair and lithium dendrite suppression, thus delaying battery degradation from a mechanistic perspective.

[0110] 3. Intelligent Adaptation and Dynamic Optimization: Maintenance parameters in the embodiments of this application ( , It can be adjusted in real time according to SOH and temperature, and convergence judgment is made based on the improvement rate of charge transfer resistance during maintenance, realizing closed-loop control and dynamic optimization of the maintenance process, and ensuring maximum maintenance effect.

[0111] 4. Multiple safety safeguards: A comprehensive safety mechanism is designed, from safety pre-judgment to three-level thermal protection and rapid exit in case of abnormality, which significantly improves the safety of the maintenance process and prevents battery damage or safety accidents caused by improper maintenance.

[0112] 5. High compatibility and traceability: By acquiring battery chemical system parameters through a BMS, the method can automatically adapt to various mainstream battery systems such as NMC, LFP, and LCO. Simultaneously, the entire process of data recording provides data support for battery life trend analysis and maintenance compliance.

[0113] Based on the same inventive concept, this application also provides a battery maintenance system. It should be noted that the system illustrated below is an example of a system corresponding to one of the above method embodiments, while in other system embodiments, the functions and number of unit modules can be set accordingly based on the aforementioned method embodiments.

[0114] like Figure 4As shown, the battery maintenance system comprises: a communication module 1 configured to perform bidirectional data interaction with the battery management system; a data acquisition module 2 configured to acquire battery data of the battery management system and perform electrochemical impedance spectroscopy scanning; a master control unit 3 connected to the communication module and the data acquisition module and configured to estimate the SOH value of the battery based on the battery data and the impedance spectroscopy scanning result, and set the frequency of the pulse current used for maintenance based on the SOH value and the battery temperature and duty cycle ; generate a PWM control signal based on the frequency and duty cycle , and maintain the battery according to a multi-stage charging and discharging protocol; a power conversion module 4 connected to the master control unit and configured to convert input alternating current into direct current; and a pulse current driving module 5 connected to the master control unit and the power conversion module and configured to modulate the direct current into high-frequency square-wave pulse current based on the PWM control signal and output to the battery.

[0115] Specifically, the master control unit 3 in the embodiment of the present application can adopt a microprocessor (such as ARM Cortex-M series), which is responsible for executing all control algorithms, generating high-precision adjustable PWM signals, collecting sensor data, scheduling module tasks, and internally building SOH evaluation and temperature control logic.

[0116] PWM control characteristics:

[0117] Frequency range: 0-2000Hz ±1Hz (resolution 0.1Hz).

[0118] Duty cycle range: 10%-90% ±0.5% (resolution 0.1%).

[0119] SOH grading strategy is:

[0120] SOH>90%: standard mode ( ), SOH 70-90%: enhanced mode ( ×1.2), SOH<70%: flexible mode ( ×0.8).

[0121] Temperature protection: when T<0℃, the hardware forcibly limits f_max=500Hz.

[0122] Support external CAN bus access to realize multi-module collaborative control.

[0123] Power conversion module 4: using TP-PFC circuit and LLC resonant converter two-stage structure, AC 220V power efficient (conversion efficiency ≥ 95%) to 200-800V adjustable stable DC bus voltage, with soft start and short circuit protection function. Specifically: after input AC 220V power, after EMI filtering, surge suppression, rectifier bridge, TP-PFC power factor correction, 400V or so bus voltage is provided, and 200-800V adjustable DC voltage is output by LLC resonant converter for pulse current driving module 5. The module is designed with isolation transformer and multiple output interfaces, with soft start and short circuit protection.

[0124] Circuit topology: AC input→TP-PFC circuit→LLC resonant converter→200-800V DC output.

[0125] Key parameters include: conversion efficiency ≥ 95% (full load condition), voltage ripple < 100mVp-p, overload protection threshold 120%.

[0126] Pulse current driving module 5: connected to main control unit 3, using full-bridge topology, controlled by magnetic isolation driving chip to output high peak current (up to 300A), low harmonic distortion (THD < 5%) high frequency square wave pulse. The output end is connected in parallel with LC filter circuit to shape the pulse waveform, ensuring that the rising time of the driving pulse is ≤ 200ns.

[0127] Data acquisition module 2: composed of high-precision sampling resistor and power monitoring chip, supporting sampling rate above 10kHz, measuring output voltage, current, power and temperature rise. The voltage division accuracy is ± 0.05% (high-precision resistor network), the isolation voltage is 2500Vrms, and the acquisition results are transmitted to the main control unit through bus and used for dynamic adjustment of logic judgment.

[0128] Communication module 1: integrated with MCP2562 CAN transceiver, supporting CAN 2.0B protocol, realizing bidirectional communication with new energy vehicle BMS system, reading SOC, battery temperature, running state and other parameters, and uploading maintenance data. The module has ESD protection and automatic baud rate identification function.

[0129] In an optional embodiment, as shown in Figure 5 the system further comprises a heat dissipation and protection module 7, which is internally provided with a temperature monitoring point at the IGBT junction temperature point, the surface of the electrolytic capacitor and the cooling liquid outlet; the data acquisition module is further used to acquire the temperature of the temperature monitoring point; and the main control unit is further used to: when the temperature is greater than or equal to a first threshold value and less than a second threshold value, linearly reducing the duty cycle and selectively reducing the frequency ; when the temperature is greater than or equal to a second threshold value and less than a third threshold value, forcibly limiting the upper limit of the frequency and reducing the average output current; when the temperature is greater than or equal to the third threshold value or the temperature sensor fails, shutting down the pulse current and cutting off the output; wherein the third threshold value > the second threshold value > the first threshold value.

[0130] Specifically, three thermal detection points (IGBT junction temperature, electrolytic capacitor surface temperature, and cooling liquid outlet temperature) are arranged in the heat dissipation and protection module 7, and a three-level protection strategy includes:

[0131] First-level protection (soft limit): when the temperature is greater than or equal to 65°C (first threshold value), linearly reducing the duty cycle.

[0132] Second-level protection (derating): when the temperature is greater than or equal to 75°C (second threshold value), forcibly limiting the frequency and reducing the current.

[0133] Third-level protection (shutdown): when the temperature is greater than or equal to 85°C (third threshold value) or the sensor is lost, immediately shutting down the output and alarming.

[0134] In addition, an overcurrent fuse (300A / 500ms fuse) and an overvoltage rapid shutdown (within 10μs) are also included in the hardware as secondary hardware protection.

[0135] In an embodiment, the system is compatible with the following battery systems: ternary lithium (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), and lithium titanate (LTO).

[0136] Supporting series number S = 4-180, working voltage range 12-800V, with wide voltage recognition ability and reverse connection protection mechanism.

[0137] Preferably, the system further includes a human-computer interaction module 8: equipped with a capacitive touch screen, displaying real-time battery parameters, running data, waveform curves, and maintenance progress, etc. Supporting password protection, user permission grading, multi-language interface switching.

[0138] The embodiment realizes intelligent maintenance of new energy batteries by outputting high-frequency pulse current with adjustable frequency and duty cycle, combining three-level thermal protection mechanism and multi-stage charging and discharging protocol, under the premise of safety, improving the efficiency of charge transfer dynamics, inhibiting polarization accumulation and thermal stress, thereby improving the service life and safety of new energy batteries.

[0139] The embodiment of the application also provides a computer readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to realize the steps of the battery maintenance method.

[0140] ​Any technical features in the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations are described, however, as long as there is no conflict in combining the technical features, it should be considered that the combination is within the scope of the present disclosure.

[0141] The above-described embodiments only express several implementation manners of the present application, and the description is specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

[0142] Ordinary skilled persons in the art can understand that the above-described embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A method of maintaining a battery, characterized by, The method comprises the following steps: acquiring battery data of a battery management system and performing an electrochemical impedance spectroscopy scan; estimating an SOH value of the battery based on the battery data and the impedance spectroscopy scan result; Adaptively setting a frequency of a pulse current used for maintenance based on the SOH value and a battery temperature and a duty cycle ; wherein the frequency of the pulse current used for the maintenance is adaptively set comprising: fitting the impedance spectroscopy scan result based on an equivalent circuit model to obtain a charge transfer resistance and a double-layer capacitance; calculating a theoretical optimal frequency according to the charge transfer resistance and the double-layer capacitance; determining a frequency amplification coefficient based on the SOH value and obtaining a temperature compensation coefficient based on a battery temperature and an ambient temperature; Adjust the theoretical optimal frequency based on the frequency amplification coefficient and the temperature compensation coefficient to obtain a target frequency, and limit the target frequency in a preset frequency range to obtain the frequency ; Adaptive setting of the duty cycle of the pulse current used for maintenance , comprising: calculating an initial duty cycle based on the battery temperature and the ambient temperature; calculating a thermal constraint duty cycle based on an allowed heat dissipation power, a bus voltage and a pulse peak current predicted or measured by a thermal model; taking the smaller value of the initial duty cycle and the thermal constraint duty cycle, and limiting the smaller value within a preset duty cycle range to obtain the duty cycle ; based on the set frequency and duty cycle applying high frequency pulsed current to the battery, maintaining the battery according to a multi-stage charge and discharge protocol.

2. The method of claim 1, wherein, before the step of acquiring the battery data of the battery management system, the method further comprises the following steps: determining whether any of the following conditions exists: a single cell voltage exceeds a limit value, a voltage difference between cells exceeds an equalization threshold, an insulation fault exists or a high-voltage relay is not closed, a battery temperature exceeds a permissible range, or an instruction of BMS maintenance prohibition is received; if any of the conditions exists, stopping the subsequent steps and issuing a warning.

3. The method of claim 1, wherein, The step of estimating the SOH value of the battery based on the battery data and the scan result comprises the following steps: estimating the SOH value of the battery by using the following formula: wherein, represents the effective capacity estimated from the near-periodic coulomb integration or charge-discharge recording, is the rated capacity of the new battery, represents the effective capacity estimated from the high-frequency internal resistance and the charge transfer resistance is the equivalent impedance calculated comprehensively, is the initial impedance reference value of the new battery, is the calibration weight factor.

4. The method of claim 1, wherein, The step of estimating the SOH value of the battery based on the battery data and the scan result comprises the following steps: estimating the SOH value of the battery by using the following formula: wherein, Rct represents the charge transfer resistance obtained from the impedance spectrum scan fitting, Rct0 represents the initial charge transfer resistance of the new battery, Rs represents the solution resistance obtained from the impedance spectrum scan fitting, Rs0 represents the solution resistance of the new battery, is a calibration weight factor.

5. The method of claim 1, wherein, determining a frequency amplification coefficient based on the SOH value comprising: When SOH > 90%, = 1.0; When 70% < SOH < 90%, = 1.2; When SOH < 70%, = 0.

8.

6. The method of claim 1, wherein, after the step of obtaining the theoretical optimal frequency, the method further comprises the following steps: determining a correction coefficient, and correcting the theoretical optimal frequency based on the correction coefficient to obtain a corrected frequency; The step of adjusting the theoretical optimal frequency based on the frequency amplification coefficient and the temperature compensation coefficient to obtain a target frequency further comprises the following step: adjusting the corrected frequency based on the frequency amplification coefficient and the temperature compensation coefficient to obtain the target frequency.

7. The method of claim 1, wherein, The multi-stage charging and discharging protocol comprises the following steps: in a first stage when the state of charge of the battery is 0% to 80%, performing constant current charging by using a high-frequency pulse current; in a second stage when the state of charge of the battery is 80% to 100%, performing constant voltage control while charging by using the high-frequency pulse current, so that the single cell voltage does not exceed the upper limit voltage given by the battery management system; in a third stage when the state of discharge of the battery is 100% to 20%, performing constant current discharging by using a low-frequency pulse current.

8. The method of claim 7, wherein, After the step of maintaining the battery according to the multi-stage charging and discharging protocol, the method further comprises the following steps: performing an electrochemical impedance spectroscopy scan again to obtain a charge transfer resistance after maintenance; calculating a change rate of the charge transfer resistance before and after maintenance; If the absolute value of the change rate is less than a preset threshold, it is determined that the maintenance converges; otherwise, the frequency is adjusted and a duty cycle and enters a next round of maintenance.

9. The method of claim 1, wherein, The method further comprises the following steps: monitoring the temperature of a temperature monitoring point; linearly decreasing the duty cycle when the temperature is greater than or equal to a first threshold and less than a second threshold and selectively decreasing the frequency ; When the temperature is greater than or equal to the second threshold and less than the third threshold, the frequency is limited. The upper limit is increased and the average output current is reduced; when the temperature is greater than or equal to the third threshold value or the temperature sensor fails, turning off the pulse current and cutting off the output; wherein the third threshold value > the second threshold value > the first threshold value.

10. A battery maintenance system applied to the battery maintenance method according to any one of claims 1 to 9, characterized by, The device comprises the following components: a communication module configured to perform bidirectional data interaction with a battery management system; a data acquisition module configured to acquire battery data of the battery management system and perform an electrochemical impedance spectroscopy scan; A master control unit connected to the communication module and the data acquisition module is configured to estimate the SOH value of the battery based on the battery data and the impedance spectrum scanning result, and set the frequency of the pulse current used for maintenance based on the SOH value and the battery temperature and duty cycle ; generate a PWM control signal based on the frequency and duty cycle , and perform maintenance on the battery according to a multi-stage charge-discharge protocol; a power conversion module connected to the main control unit and configured to convert input alternating current into direct current; A pulse current driving module connected to the main control unit and the power conversion module is configured to modulate the direct current into high-frequency square-wave pulse current based on the PWM control signal and output to the battery.

11. The battery maintenance system of claim 10, wherein, The system further comprises: A heat dissipation and protection module including temperature monitoring points arranged at an IGBT junction temperature point, an electrolytic capacitor surface, and a cooling liquid outlet; The data acquisition module is further configured to acquire temperatures of the temperature monitoring points; The master control unit is further configured to linearly decrease the duty cycle when the temperature is greater than or equal to a first threshold and less than a second threshold and selectively decrease the frequency ; When the temperature is greater than or equal to the second threshold and less than the third threshold, the frequency is limited. The upper limit is increased and the average output current is reduced; When the temperature is greater than or equal to a third threshold value or the temperature sensor fails, the pulse current is turned off and the output is cut off. The third threshold value is greater than the second threshold value, and the second threshold value is greater than the first threshold value.

12. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program, when executed by a processor, implements the steps of the battery maintenance method according to any one of claims 1 to 9.

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