Battery maintenance method and system and medium

Abstract

The invention provides a battery maintenance method and system and a medium. Comprising the following steps: acquiring battery data of a battery management system, and executing electrochemical impedance spectroscopy scanning; estimating the SOH value of the battery based on the battery data and the impedance spectrum scanning result; based on the SOH value and the battery temperature, adaptively setting the frequency and duty ratio of the pulse current for maintenance; and applying high-frequency pulse current to the battery based on the set frequency and duty ratio, and maintaining the battery according to a multi-stage charging and discharging protocol. The embodiment of the invention can prolong the service life and improve the use safety of the new energy battery.

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 whole 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., and it is difficult to meet the differentiated and refined maintenance needs of complex application environments (such as high and low temperatures, vibration) and diversified 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: 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.

[0006] 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 The 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 impedance spectrum scanning results; and set the frequency of the maintenance pulse current based on the SOH value and the battery temperature. and duty cycle Based on the frequency and duty cycle The system generates a PWM control signal and maintains the battery according to a multi-stage charge and discharge protocol; the power conversion module, connected to the main control unit, is configured to convert the input AC power into DC power; the pulse current drive module, connected to the main control unit and the power conversion module, is configured to modulate the DC power into a high-frequency square wave pulse current based on the PWM control signal and output it to the battery.

[0007] A third aspect of this application provides a computer-storable medium. A computer program is stored thereon, which, when executed by a processor, implements the steps of the battery maintenance method described above.

[0008] Compared to existing technologies, this application's embodiments achieve accurate estimation of the battery's internal state of health (SOH) by integrating battery management system (BMS) data and electrochemical impedance spectroscopy (EIS) scanning. This breaks away from the traditional "one-size-fits-all" maintenance model, providing a customized maintenance solution for each battery. The use of high-frequency pulsed current with adjustable frequency and duty cycle effectively suppresses electrode polarization, improves ion migration efficiency, and has a positive effect on SEI film repair and lithium dendrite suppression, thus mechanistically delaying battery degradation. Furthermore, the maintenance parameters of this application's embodiments ( , 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. Attached Figure Description

[0009] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0010] Figure 1 This is a flowchart of a battery maintenance method according to an embodiment of this application; Figure 2 This is a flowchart illustrating the setting of the frequency of the pulse current used for maintenance according to one embodiment of this application; Figure 3 This is a flowchart illustrating the setting of the duty cycle of the pulse current used for maintenance according to one embodiment of this application; Figure 4 This is a schematic diagram of the structure of a battery maintenance system according to an embodiment of this application; Figure 5 This is a schematic diagram of a battery maintenance system according to another embodiment of this application. Detailed Implementation

[0011] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] It should be noted that the following description covers various aspects of embodiments within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0013] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0014] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0015] Based on this, embodiments of this application provide a battery maintenance method, such as... Figure 1 As shown, it includes the following steps: In step 101, battery data from the battery management system is acquired, and an electrochemical impedance spectroscopy scan is performed.

[0016] In this embodiment, battery management system (BMS) data can be acquired via the CAN bus. For example, an MCP2562 CAN transceiver can be used to establish a communication connection with the vehicle or battery pack's BMS to periodically read battery data. This battery data includes, but is not limited to, the following parameters: individual cell / pack voltage U, current I, battery state of charge (SOC), and battery temperature. Cell consistency (maximum / minimum single-cell voltage difference) The data includes the number of cycles N, historical alarm records (including abnormal events such as overvoltage, overcurrent, and overtemperature), and the upper limit voltage set by the BMS. Upper limit temperature Permission thresholds are set. When communication is abnormal or permissions are insufficient, sampling can also be performed in a local degradation mode (e.g., relying on instruments).

[0017] Meanwhile, the battery's state of charge (SOC) and temperature are within the permissible window (e.g., SOC of 40%–70%, 0℃ ≤ temperature). Electrochemical impedance spectroscopy (EIS) scans were performed on the battery pack or segmented subsystem at temperatures ≤45℃. Specifically, a small-amplitude AC current excitation of 10-100 mA rms was applied to avoid disturbing the state of charge (SOC). The frequency was swept point-by-point within the range of 0.1 Hz to 1000 Hz, and the voltage response at the same frequency was acquired and the complex impedance was calculated. Subsequently, the impedance spectrum was fitted using the Randles equivalent circuit model to obtain electrochemical parameters, including solution resistance. (OHMIC resistance of electrolyte and conductor), charge transfer resistance (Resistance to the reaction rate at the electrode / electrolyte interface), double-layer capacitance (Electric double layer capacitance formed on the electrode surface) and Warburg diffusion parameters (describe the impedance characteristics caused by the diffusion of matter within the electrode), etc.

[0018] In step 102, the battery health SOH value is estimated based on the battery data and impedance spectroscopy scan results.

[0019] In an alternative embodiment, the SOH value of the battery can be estimated using formula (1) by combining impedance spectroscopy (EIS) characteristic parameters with historical data from the battery management system (BMS): (1) in, This represents the effective capacity estimated from near-period coulomb integration or charge / discharge records. For the rated capacity of the new battery, This indicates the relationship between high-frequency internal resistance and charge transfer resistance. The equivalent impedance obtained from comprehensive calculations, This is the initial impedance reference value for the new battery. To calibrate the weighting factors, It can be calibrated experimentally. This model integrates the two core aging factors: capacitance decay and impedance growth.

[0020] In another alternative embodiment, the SOH value of the battery can be estimated using formula (2): (2) in, This represents the charge transfer resistance obtained by fitting an impedance spectrum scan. This indicates the initial charge transfer resistance of the new battery. This represents the solution resistance obtained by fitting an impedance spectral scan. This indicates the solution resistance of the new battery. , To calibrate the weighting factors, , It can be calibrated experimentally. This model directly uses the rate of change of EIS characteristic parameters to reflect health status, resulting in a more direct response.

[0021] In step 103, based on the SOH value and battery temperature, the frequency of the pulse current used for maintenance is adaptively set. and duty cycle .

[0022] Specifically, in this embodiment, the frequency of the maintenance pulse current is set based on the battery health (SOH) value and battery temperature. The method can be referred to Figure 2 The details are as follows: In step 1031, the impedance spectrum scan results are fitted based on an equivalent circuit model (such as the Randles model) to obtain the charge transfer resistance. (Unit: Ω, reflecting interfacial reaction rate) and double-layer capacitance (Unit: F, reflecting the energy storage capacity of the electrode surface).

[0023] In step 1032, based on the charge transfer resistor and double-layer capacitor The theoretical optimal frequency was calculated. Optimal frequency The calculation formula is as follows:

[0024] To compensate for the discrepancy between the theoretical model and the actual interfacial reaction and to improve applicability, a correction coefficient can be introduced. Based on the correction coefficient For the theoretical optimal frequency Make corrections to obtain the correction frequency. To make it closer to the characteristic frequency of the electrochemical process, the frequency was corrected. It can be represented as:

[0025] This range is a reasonable range of values ​​determined by statistical analysis of the impedance spectrum characteristic points of various battery systems (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, so as to ensure the activation effect and avoid excessive polarization and side reactions.

[0026] The specific value can be dynamically set based on the battery health status (SOH) and temperature (T), and a graded selection strategy is adopted as shown in Table 1: Table 1:

[0027] As the state of electrolyte (SOH) decreases, the electrode / electrolyte interface film thickens, charge transfer impedance increases, and double-layer capacitance decreases, leading to a decrease in characteristic frequency. It should decrease as SOH decreases.

[0028] Increasing the temperature promotes ion migration and reaction kinetics, allowing for higher excitation frequencies; however, when the temperature is too low, ion diffusion is limited, and the frequency should be reduced. To suppress polarization and thermal stress.

[0029] also, The value of is also related to the differences in the system. For example, ternary systems such as NMC / NCA have higher reaction rates, so it is recommended to use . =0.18-0.20; LFP and other systems have relatively slow dynamics, so it is recommended to take 0.18-0.20. =0.15-0.18.

[0030] During system operation, the control unit can automatically adjust based on real-time detected changes in SOH, temperature, and impedance. Value. For example, when a temperature drop or a decrease in SOH is detected, the system automatically lowers the value. When the temperature rises or the condition recovers, it gradually returns to the default upper limit value. Through this dynamic adjustment mechanism, adaptive control of the pulse frequency can be achieved, ensuring that the maintenance process is always within the optimal excitation range.

[0031] In step 1033, the frequency amplification factor is determined based on the SOH value. A temperature compensation coefficient is obtained based on the battery temperature and ambient temperature. Specifically, in this step, the frequency amplification coefficient can be adjusted according to the battery health status (SOH). Frequency amplification factor The method for determining it is as follows: When SOH > 90% = 1.0; When 70% ≤ SOH ≤ 90%, = 1.2; When SOH < 70% = 0.8 In this embodiment, the temperature compensation coefficient is obtained based on the battery temperature and the ambient temperature. This can be achieved by first determining the battery temperature... and ambient temperature Define correction temperature , = Then, based on the corrected temperature Calculate the compensation coefficient , , .

[0032] In step 1034, the theoretical optimal frequency is adjusted based on the frequency amplification factor and temperature compensation factor to obtain the target frequency, and the target frequency is then limited to a preset frequency range to obtain the desired frequency. .

[0033] Preferably, in this embodiment, the target frequency can also be the corrected frequency based on the frequency amplification factor and the temperature compensation factor. After adjustment, the target frequency is limited to a preset frequency range, and the resulting frequency is... for: .in It can be set to 100 Hz. It can be set to 2000 Hz.

[0034] Additionally, in this embodiment of the application, when the temperature is corrected... Hardware limiting can be performed at that time. =500Hz.

[0035] 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: 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).

[0036] 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. ;

[0037] 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).

[0038] 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.

[0039] While adjusting the duty cycle, the system can also limit the peak current, average current, and upper voltage limit separately, such as:

[0040] in: Average current; This is the battery's rated current. This is the peak pulse current; The pulse limit current that the battery can withstand; This refers to the voltage of a single cell. The upper limit of the unit voltage provided for the BMS.

[0041] When any threshold is approached and an alert is triggered, the duty cycle can be reduced sequentially according to priority. Or reduce the frequency Alternatively, it may enter a cooling delay phase.

[0042] In step 104, based on the set frequency and duty cycle A high-frequency pulse current is applied to the battery to maintain it according to a multi-stage charge and discharge protocol.

[0043] Specifically, the multi-stage charge-discharge protocol of this application includes: During the first stage when the battery's state of charge is 0% to 80%, constant current charging is performed using high-frequency pulse current; during the second stage when the battery's state of charge is 80% to 100%, constant voltage control is superimposed while high-frequency pulse current charging is performed to ensure that the voltage of each individual cell does not exceed the upper limit voltage given by the battery management system; during the third stage when the battery's state of discharge is 100% to 20%, constant current discharging is performed using low-frequency pulse current.

[0044] In the first stage (SoC 0%–80%), constant current charging is performed using a high-frequency pulsed current: (Upper limit can be set to 2000 Hz) Output square wave pulse; high-frequency pulses help reduce interface polarization (i.e. This improves the transient response and increases the lithium-ion migration rate, resulting in a more uniform insertion process. 2000Hz is an empirically preferred value, but it can also be fine-tuned within the range of [1000Hz–2000Hz]. The current amplitude range is [0.01C–3C] (dynamically limited based on BMS allowable values ​​and heat dissipation capacity). The "C-rate" is defined as follows: ,in This refers to the battery's nominal capacity (Ah), converted to amperes. 0.01C: 100-hour charging current; 3C: 20-minute charging current.

[0045] Duty cycle according to The duty cycle is set to [20%–80%]. A low duty cycle results in intermittent current, which is beneficial for heat dissipation; a high duty cycle results in a large average current, which accelerates charging. The system adaptively adjusts within the specified range. Temperature and voltage are monitored in real time. If any abnormality is detected... Or the individual unit voltage is close to First, reduce the duty cycle, then reduce the frequency, and if necessary, insert a cooling interval (0% duty cycle, duration 10–60s). For example: Perform incremental capacity analysis (ICA) every 30 seconds to monitor the characteristic peak of lithium plating at the anode: If a voltage plateau characteristic peak is detected: reduce the duty cycle by 10% and increase the pulse frequency to 2500Hz.

[0046] Cutoff conditions (phase 1 stops when any one of them is met): SoC ≥ 80%, voltage difference of any single cell > 50mV, cumulative charging time > 60min.

[0047] In the second stage (SoC 80%–100%), pulse + constant voltage compensation is employed: pulse maintenance (high frequency is beneficial for interface updates and polarization release) is maintained, and a constant voltage control loop is superimposed to ensure that the unit voltage does not exceed the value given by the BMS. (e.g., 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 ( When, prioritize reducing If the limit is reached but still exceeds the limit, then the reduction will be applied. Alternatively, it can switch to trickle hold (duty cycle ≤ 20%). During this stage, the pulse frequency is: Maintaining high-frequency pulses helps preserve electrode interface activity and reduce concentration polarization. Duty cycle 20%–80% come from the optimal values ​​calculated during the parameter setting phase: voltage constraint U≤ The system samples the individual cell voltage in real time to prevent overcharging.

[0048] Constant voltage control: 4.20 ± 0.03V superimposed (using a high-precision reference voltage source ADR4540).

[0049] Current decay law: It decays linearly or exponentially with time t (minutes). The specific formula can be set as follows: Or other control strategies.

[0050] Special handling: When →A 1-second zero-current relaxation period is inserted every 10 pulses, increasing the temperature sampling frequency to 1Hz.

[0051] Cut-off conditions (phase 2 stops when any one of them is met): charging current ≤ 0.05C, cumulative time > 120min, SoC ≥ 95% and voltage stable (ΔV < 1mV / 10s).

[0052] Phase switching rules: Phase 2 → Phase 3: SoC ≥ 95% or I ≤ 0.1C → switch after 30-second buffer.

[0053] In the third stage (SoC 100%–20%), pulsed discharge shaping is employed. =100Hz, I=0.01C-0.5C constant current pulse discharge is used to activate the negative electrode and reduce residual polarization under high SOC; the discharge stops when the SoC drops to 20% or reaches the time, temperature rise, or cycle limit. It may be coordinated with the BMS equalization strategy when necessary (to maintain intra-packet consistency). Duty cycle To ensure a minimum of 70% and maintain continuous discharge energy.

[0054] Security mechanisms: Voltage protection: Discharge is suspended when the individual cell voltage is ≤2.8V and resumes when it recovers to 3.0V.

[0055] Temperature compensation: = For every 1°C decrease, the duty cycle increases by 0.5% to ensure energy output at low temperatures.

[0056] Energy recovery: The regenerative braking circuit is activated during pulse shutdown, with a recovery efficiency of ≥85%.

[0057] Deadline: SoC ≤ 20%, voltage drop dV / dt > 50mV / s, cumulative time > 180min.

[0058] Phase switching rules: Phase 3 Termination: SoC≤20% or dV / dt>50mV / s → Immediate termination.

[0059] The phase transition rules for the three are as follows: Phase 1 → Phase 2: SoC ≥ 80% and ΔV < 1mV / 10s (immediate switching).

[0060] Phase 2 → Phase 3: SoC ≥ 95% or I ≤ 0.01C (switch after 30s buffer).

[0061] Phase 3 → Termination: SoC ≤ 20% or dV / dt > 50mV / s.

[0062] In a preferred embodiment, after maintaining the battery according to a multi-stage charge-discharge protocol, the method further includes: performing an electrochemical impedance spectroscopy scan again to obtain the charge transfer resistance after maintenance; calculating the rate of change of the charge transfer resistance before and after maintenance; if the absolute value of the rate of change is less than a preset threshold, then maintenance is determined to have converged and terminated; otherwise, the frequency is adjusted. and duty cycle Then proceed to the next round of maintenance. Specifically, a rest / retest window (e.g., 5 minutes) can be set between the three-stage charge / discharge protocols to perform a fast impedance spectroscopy (EIS) scan again (which can be shortened to the representative frequency). This is done to improve the charge transfer resistance rate. (The rate of change of charge transfer resistance before and after maintenance) is used as a convergence index: if the absolute value of the rate of change Less than a preset threshold (e.g.) If the temperature rise benefit ratio is below the threshold, then maintenance is considered convergent and the effect is significant, and the task ends. Otherwise, minor adjustments are made according to the principle of "making minor changes without increasing the severity". , And then proceed to the next round of short-cycle maintenance.

[0063] The decision-making logic is as follows: : Maintain parameters and continue maintenance Maintenance terminated. Reduce frequency by 10% + duty cycle by 5%.

[0064] Termination conditions: Two consecutive cycles Cumulative temperature rise / Period, BMS report individual imbalance .

[0065] In other embodiments, the number of iterations can also be set as the convergence condition, such as a maximum number of iterations. Rounds (e.g., ≤5), or convergence conditions based on duration (e.g., setting a maximum duration to automatically end).

[0066] Preferably, embodiments of this application also include performing a safety check before proceeding with substantive maintenance. For example, before acquiring battery data from the battery management system, it is determined whether any of the following conditions exist: the voltage of a single cell exceeds a limit, or the voltage difference between cells exceeds a limit. If any of the following conditions are met, the maintenance procedure will be stopped, an audible and visual warning will be issued, and the fault code will be recorded to ensure operational safety: the battery temperature exceeds the equalization threshold, there is an insulation fault or the high-voltage relay is not closed, the battery temperature exceeds the permissible range, or a BMS instruction prohibiting maintenance is received.

[0067] Preferably, embodiments of this application further include a three-level thermal protection mechanism, including: Monitor the temperature at monitoring points (such as IGBT junction temperature, electrolytic capacitor surface temperature, and coolant outlet temperature); when the temperature is greater than or equal to a first threshold and less than a second threshold, linearly reduce the duty cycle. And selectively reduce the frequency. When the temperature is greater than or equal to the second threshold and less than the third threshold, the frequency is forcibly limited. The upper limit is set 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 > the second threshold > the first threshold.

[0068] For example: Level 1 (Soft Limit): When the temperature T at the monitoring point is ≥ 65℃ (first threshold), the duty cycle is linearly reduced to 20%, and the frequency is reduced by 20% if necessary.

[0069] Level 2 (Decrease): When T ≥ 75℃ (second threshold), forced =500 Hz, the average current drops to 50% of the rated value.

[0070] Level 3 (Shutdown): If T≥85℃ (third threshold) or any temperature sensor fails to connect / exceeds its limit, immediately shut down the PWM output, disconnect the main contactor, and trigger an alarm.

[0071] In this embodiment, the system will immediately and safely exit if any of the following conditions occur: BMS rejection, individual unit overvoltage / undervoltage, overcurrent, insulation fault, emergency stop triggering, or CAN heartbeat loss timeout. The exit procedure includes: reducing current → shutting down PWM → disconnecting high voltage → recording fault codes.

[0072] This application also includes data recording and traceability: timestamp recording of the entire process. , It includes U / I / T, EIS features, SOH curves, and event codes, and supports local / host computer export for life trend analysis and maintenance compliance certification.

[0073] 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.

[0074] Compared with the prior art, the embodiments of this application have the following advantages: 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] like Figure 4 As shown, the battery maintenance system includes: 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 from the battery management system and perform electrochemical impedance spectroscopy (EIS) scanning; and a main control unit 3 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 EIS scanning results; and set the frequency of the pulse current used for maintenance based on the SOH value and the battery temperature. and duty cycle Based on the frequency and duty cycle The system generates a PWM control signal and maintains the battery according to a multi-stage charge and discharge protocol; the power conversion module 4, connected to the main control unit, is configured to convert the input AC power into DC power; the pulse current drive module 5, connected to the main control unit and the power conversion module, is configured to modulate the DC power into a high-frequency square wave pulse current based on the PWM control signal and output it to the battery.

[0081] Specifically, in this embodiment, the main control unit 3 can be a microprocessor (such as the ARM Cortex-M series) responsible for executing all control algorithms, generating high-precision adjustable PWM signals, collecting sensor data, scheduling tasks of each module, and having built-in SOH evaluation and temperature control logic.

[0082] PWM control characteristics: Frequency range: 0-2000Hz ±1Hz (resolution 0.1Hz).

[0083] Duty cycle range: 10%-90% ±0.5% (resolution 0.1%).

[0084] The SOH grading strategy is as follows: SOH>90%: Standard mode ( SOx 70-90%: Enhanced mode ( ×1.2), SOH<70%: Flexible mode ( ×0.8).

[0085] Temperature protection: When T < 0℃, the hardware will force a limit of f_max = 500Hz.

[0086] It supports external CAN bus access to enable multi-module collaborative control.

[0087] Power Conversion Module 4: Employing a two-stage structure of TP-PFC circuit and LLC resonant converter, it efficiently (conversion efficiency ≥95%) converts AC220V mains power into a stable DC bus voltage adjustable from 200-800V, featuring soft-start and short-circuit protection. Specifically, after inputting AC 220V mains power, it passes through EMI filtering, surge suppression, a rectifier bridge, and TP-PFC power factor correction to provide a bus voltage of approximately 400V. The LLC resonant converter then outputs an adjustable DC voltage of 200–800V to power the pulse current drive module 5. This module incorporates an isolation transformer and multiple output interfaces, and features soft-start and short-circuit protection.

[0088] Circuit topology: AC input → TP-PFC circuit → LLC resonant converter → 200-800V DC output.

[0089] Key parameters include: conversion efficiency ≥95% (full load condition), voltage ripple <100mVp-p, and overload protection threshold 120%.

[0090] Pulse current drive module 5: Connected to main control unit 3, it adopts a full-bridge topology and controls high-speed MOSFET / IGBT switching devices through a magnetically isolated drive chip, outputting high peak current (up to 300A) and low harmonic distortion (THD<5%) high-frequency square wave pulses. An LC filter circuit is connected in parallel at the output to shape the pulse waveform, ensuring that the rise time of the drive pulse is ≤200ns.

[0091] Data acquisition module 2: Composed of a high-precision sampling resistor and a power monitoring chip, supporting sampling rates above 10kHz, measuring output voltage, current, power, and temperature rise. Voltage divider accuracy ±0.05% (high-precision resistor network), isolation voltage 2500Vrms, and acquisition results are processed via... The data is transmitted to the main control unit via the bus and used to dynamically adjust the logic judgment.

[0092] Communication Module 1: Integrates CAN transceivers such as the MCP2562, supports the CAN 2.0B protocol, and enables bidirectional communication with the BMS system of new energy vehicles. It can read parameters such as SOC, battery temperature, and operating status, and can also upload maintenance data. The module features ESD protection and automatic baud rate recognition.

[0093] In an alternative embodiment, such as Figure 5 As shown, the system also includes a heat dissipation and protection module 7, which has temperature monitoring points located at the IGBT junction temperature, the surface of the electrolytic capacitor, and the coolant outlet. The data acquisition module is also used to collect the temperature at the monitoring points. The main control unit is also used to linearly reduce the duty cycle when the temperature is greater than or equal to a first threshold and less than a second threshold. And selectively reduce the frequency. When the temperature is greater than or equal to the second threshold and less than the third threshold, the frequency is forcibly limited. The upper limit is set 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 > the second threshold > the first threshold.

[0094] Specifically, the heat dissipation and protection module 7 is equipped with three thermistor detection points (IGBT junction temperature, electrolytic capacitor surface temperature, and coolant outlet temperature), and the three-level protection strategy includes: Level 1 protection (soft limit): When the temperature is ≥65℃ (first threshold), the duty cycle is linearly reduced.

[0095] Secondary protection (derating): When the temperature is ≥75℃ (second threshold), the frequency is forcibly limited and the current is reduced.

[0096] Level 3 protection (shutdown): When the temperature is ≥85℃ (third threshold) or the sensor is disconnected, the output will be immediately shut off and an alarm will be triggered.

[0097] In addition, the hardware includes an overcurrent fuse (300A / 500ms blowout) and overvoltage fast shutdown (within 10μs) as secondary hardware protection.

[0098] In one 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).

[0099] It supports series connection number S=4–180, operating voltage range 12–800V, and has wide voltage identification capability and reverse connection protection mechanism.

[0100] Preferably, this system also includes a human-machine interaction module 8: equipped with a capacitive touchscreen, displaying real-time battery parameters, operating data, waveform curves, and maintenance progress. It supports password protection, hierarchical user access control, and multi-language interface switching.

[0101] This embodiment improves charge transfer kinetic efficiency and suppresses polarization accumulation and thermal stress by outputting a high-frequency pulse current with adjustable frequency and duty cycle, combined with a three-level thermal protection mechanism and a multi-stage charge and discharge protocol, while ensuring safety. This enables intelligent maintenance of new energy batteries and improves their lifespan and safety.

[0102] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the battery maintenance method described above.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0105] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A battery maintenance method, characterized in that, include: Acquire battery data from the battery management system and perform electrochemical impedance spectroscopy scans; The SOH value of the battery is estimated based on the battery data and impedance spectroscopy scan results; Based on the SOH value and battery temperature, the frequency of the pulse current used for maintenance is adaptively set. and duty cycle ; Based on the set frequency and duty cycle A high-frequency pulse current is applied to the battery to maintain it according to a multi-stage charge and discharge protocol.

2. The battery maintenance method according to claim 1, characterized in that, Before acquiring the battery data from the battery management system, the process also includes: Determine if any of the following conditions exist: the single cell voltage exceeds the limit, the voltage difference between cells exceeds the equalization threshold, there is an insulation fault or the high-voltage relay is not closed, the battery temperature exceeds the permissible range, or a BMS instruction to prohibit maintenance is received; If any of the aforementioned situations exist, the subsequent steps will be stopped and a warning will be issued.

3. The battery maintenance method according to claim 1, characterized in that, The estimation of the SOH value of the battery based on the battery data and scan results includes: The SOH value of the battery is estimated using the following formula: in, This represents the effective capacity estimated from near-period coulomb integration or charge / discharge records. For the rated capacity of the new battery, This represents the high-frequency internal resistance and charge transfer resistance. The equivalent impedance obtained from comprehensive calculations, This is the initial impedance reference value for the new battery. To determine the weighting factor.

4. The battery maintenance method according to claim 1, characterized in that, The estimation of the SOH value of the battery based on the battery data and scan results includes: The SOH value of the battery is estimated using the following formula: in, This represents the charge transfer resistance obtained by fitting an impedance spectrum scan. This indicates the initial charge transfer resistance of the new battery. This represents the solution resistance obtained by fitting an impedance spectral scan. This indicates the solution resistance of the new battery. To determine the weighting factor.

5. The battery maintenance method according to claim 1, characterized in that, Based on the SOH value and battery temperature, the frequency of the pulse current used for maintenance is set. ,include: The impedance spectrum scanning results were fitted based on the equivalent circuit model to obtain the charge transfer resistance and double-layer capacitance. The theoretical optimal frequency is calculated based on the charge transfer resistance and double-layer capacitance. The frequency amplification factor is determined based on the SOH value, and the temperature compensation factor is obtained based on the battery temperature and ambient temperature. The theoretical optimal frequency is adjusted based on the frequency amplification factor and temperature compensation factor to obtain the target frequency, and the target frequency is then limited to a preset frequency range to obtain the desired frequency. .

6. The battery maintenance method according to claim 5, characterized in that, The frequency amplification factor is determined based on the SOH value. ,include: When SOH > 90%, = 1.0; When 70% ≤ SOH ≤ 90%, = 1.2; When SOH < 70%, = 0.

8.

7. The battery maintenance method according to claim 5, characterized in that, After obtaining the theoretically optimal frequency, the process also includes: Determine the correction coefficient, and correct the theoretical optimal frequency based on the correction coefficient to obtain the corrected frequency; The step of adjusting the theoretical optimal frequency based on the frequency amplification factor and temperature compensation factor to obtain the target frequency further includes: The corrected frequency is adjusted based on the frequency amplification factor and temperature compensation factor to obtain the target frequency.

8. The battery maintenance method according to claim 1, characterized in that, Based on the SOH value and battery temperature, the duty cycle of the pulse current used for maintenance is set. ,include: The initial duty cycle is calculated based on battery temperature and ambient temperature. Calculate the thermal constraint duty cycle 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. 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. .

9. The battery maintenance method according to claim 1, characterized in that, The multi-stage charge / discharge protocol includes: During the first stage when the battery's state of charge is from 0% to 80%, constant current charging is performed using a high-frequency pulse current. During the second stage when the battery's state of charge is between 80% and 100%, constant voltage control is superimposed while high-frequency pulse current charging is used to ensure that the individual cell voltage does not exceed the upper limit voltage given by the battery management system. During the third stage when the battery's discharge state is between 100% and 20%, a constant current discharge is performed using a low-frequency pulse current.

10. The battery maintenance method according to claim 9, characterized in that, After maintaining the battery according to the multi-stage charge-discharge protocol, the process also includes: Perform another electrochemical impedance spectroscopy scan to obtain the charge transfer resistance after maintenance; Calculate the rate of change of charge transfer resistance before and after maintenance; If the absolute value of the rate of change is less than a preset threshold, then convergence is determined; otherwise, the frequency is adjusted. and duty cycle And then proceed to the next round of maintenance.

11. The battery maintenance method according to claim 1, characterized in that, The method further includes: Temperature monitoring at the monitoring point; When the temperature is greater than or equal to the first threshold and less than the second threshold, the duty cycle is linearly reduced. And selectively reduce 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 or the temperature sensor malfunctions, the pulse current is turned off and the output is cut off. Among them, the third threshold > the second threshold > the first threshold.

12. A battery maintenance system, applied to the battery maintenance method as described in any one of claims 1 to 11, characterized in that, include: The communication module is configured to perform bidirectional data interaction with the battery management system; The data acquisition module is configured to acquire battery data from the battery management system and perform electrochemical impedance spectroscopy scans. The main 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 impedance spectrum scan results; and set the frequency of the maintenance pulse current based on the SOH value and the battery temperature. and duty cycle Based on the frequency and duty cycle It generates PWM control signals and maintains the battery according to a multi-stage charge and discharge protocol; A power conversion module, connected to the main control unit, is configured to convert the input AC power into DC power; The pulse current drive module, connected to the main control unit and the power conversion module, is configured to modulate the DC current into a high-frequency square wave pulse current based on the PWM control signal and output it to the battery.

13. The battery maintenance system according to claim 12, characterized in that, The system also includes: The heat dissipation and protection module includes temperature monitoring points located at the IGBT junction temperature, the surface of the electrolytic capacitor, and the coolant outlet; The data acquisition module is also used to acquire the temperature of the temperature monitoring point; The main control unit is further configured to: linearly reduce the duty cycle when the temperature is greater than or equal to a first threshold and less than a second threshold. And selectively reduce 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 or the temperature sensor malfunctions, the pulse current is turned off and the output is cut off. Among them, the third threshold > the second threshold > the first threshold.

14. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the battery maintenance method as described in any one of claims 1 to 11.

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