Battery maintenance device and method for new energy vehicles

Abstract

This application provides a battery maintenance device and method for new energy vehicles. It includes: a power input module, a control module, a power conversion module, a detection and protection module, and a human-machine interface module. The control module is configured to control the device to operate in at least one of the following modes: Dynamic ripple modulation mode: A high-frequency, low-amplitude AC ripple signal is hardware-superimposed on the power stage output of the power conversion module, causing the battery to experience high-frequency current disturbances, while the high-frequency component can be averaged by the BMS sampling system; Gradual low-frequency command mode: A gradually changing current command with a frequency lower than its response bandwidth is sent to the BMS through a communication interface, and a limiting algorithm is used to ensure that the single-step current change does not exceed the maximum allowable ramp-up rate of the BMS. This application embodiment can achieve an equivalent battery pulse maintenance effect while meeting the vehicle BMS safety standards, effectively delaying battery degradation and reducing the total life cycle cost.

Description

Technical Field

[0001] This application relates to the field of new energy vehicle battery maintenance technology, specifically to a battery maintenance device and method for new energy vehicles. Background Technology

[0002] Power batteries are the core component of new energy vehicles, and their performance degradation directly affects the vehicle's driving range and lifespan. Research shows that high-frequency pulse charging technology can effectively suppress battery polarization, reduce internal resistance growth, and delay capacity decay. This technology has been proven effective in the laboratory and at the battery module level.

[0003] However, in vehicle applications, the Battery Management System (BMS) has strict real-time monitoring and protection logic for charging current, voltage, and temperature, and communicates with charging equipment through standard protocols such as GB / T 27930. Traditional switching-type large-amplitude pulse currents are easily identified as abnormal currents by the BMS, leading to charging interruptions. This makes it impossible to safely apply this effective maintenance technology in vehicle maintenance and after-sales scenarios.

[0004] Therefore, there is an urgent need in this field for an engineering solution that can achieve the equivalent battery pulse maintenance effect while meeting the vehicle BMS safety standards. Summary of the Invention

[0005] The purpose of this application is to provide a battery maintenance device and method for new energy vehicles, addressing the incompatibility between high-frequency pulse maintenance technology and the vehicle's BMS safety strategy. It achieves an equivalent battery pulse maintenance effect while meeting vehicle BMS safety standards, effectively delaying battery degradation and reducing total lifecycle costs.

[0006] To address the aforementioned technical problems, this application provides, in one aspect, a battery maintenance device for new energy vehicles, comprising: a power input module, a control module, a power conversion module, a detection and protection module, and a human-machine interface module; the power input module is used to connect to an external power source and provide stable DC power, and its output terminal is connected to the input terminal of the power conversion module; the power conversion module is used to perform power conversion and output controllable DC power to the battery, its output terminal is connected to the battery, and its control terminal is connected to the control module; the control module has its output terminal connected to the control terminal of the power conversion module, its communication interface connected to the vehicle's BMS, and its signal acquisition terminal connected to the detection and protection module;

[0007] The control module is configured to control the device to operate in at least one of the following modes: Dynamic ripple modulation mode: A high-frequency, low-amplitude AC ripple signal is superimposed on the power stage output of the power conversion module via hardware, causing the battery to withstand high-frequency current disturbances, while the high-frequency component can be averaged by the BMS sampling system; Gradual low-frequency command mode: A gradual current command with a frequency lower than its response bandwidth is sent to the BMS via the communication interface, and a limiting algorithm is used to ensure that the single-step current change does not exceed the maximum allowable ramp-up rate of the BMS. The detection and protection module is used to collect the required data in real time and output it to the control module, and to execute protection actions according to the instructions of the control module or a preset strategy; the human-machine interaction module is connected to the control module and is used to receive user commands, set parameters, and display the operating status of the device.

[0008] The second aspect of this application provides a battery maintenance method for new energy vehicles, applied to the aforementioned battery maintenance device, comprising: establishing a communication connection with the vehicle's BMS and reading preset parameters of the vehicle's BMS; issuing a step current command to the vehicle's BMS and measuring the response to calculate the short-time current change rate, and calculating the maximum allowable ramp rate based on the current change rate and a conservative coefficient; selecting an operating mode according to the current battery state and the characteristics of the vehicle's BMS, the operating mode including a dynamic ripple modulation mode and a gradually changing low-frequency command mode; when the dynamic ripple modulation mode is selected, generating an AC ripple signal through the ripple modulation branch in the power conversion module, and superimposing it with the reference current generated by the power conversion module to form a total output current; when the gradually changing low-frequency command mode is selected, issuing a gradually changing current command with a frequency lower than its response bandwidth to the BMS through the communication interface, and ensuring that the single-step current change does not exceed the maximum allowable ramp rate of the BMS through a limiting algorithm.

[0009] This application's embodiments cleverly bypass the BMS protection mechanism through two innovative modes, achieving equivalent pulse maintenance in a vehicle environment: The dynamic ripple modulation mode utilizes the low-pass filtering characteristics of BMS sampling, allowing the battery to sense high-frequency maintenance excitations while remaining undetected by the BMS, preserving the core advantages of laboratory pulse technology. The gradually changing low-frequency command mode operates entirely at the protocol layer, generating gradually changing commands that the BMS can safely execute through an adaptive BMS dynamic performance limiting algorithm, exhibiting excellent compatibility. This application's embodiments can be widely applied to vehicle maintenance, after-sales testing, and other scenarios, effectively delaying battery degradation and reducing total lifecycle costs. Attached Figure Description

[0010] 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.

[0011] Figure 1 This is a schematic diagram of the structure of a battery maintenance device according to an embodiment of this application;

[0012] Figure 2 This is a flowchart of a battery maintenance method according to an embodiment of this application. Detailed Implementation

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] Based on this, embodiments of this application provide a battery maintenance device for new energy vehicles, such as... Figure 1 As shown, it includes:

[0018] The system includes a power input module 1, a power conversion module 2, a control module 3, a detection and protection module 4, and a human-machine interaction module 5.

[0019] The power input module 1 is used to connect to an external power source (such as 100V / 200V AC mains power). It contains rectification, filtering and necessary overvoltage / undervoltage protection circuits to convert the external power source into stable DC power. Its output terminal is connected to the input terminal of the power conversion module 2 to provide energy for subsequent power conversion.

[0020] Power conversion module 2 is the core of the device's energy conversion. It is typically a bidirectional or unidirectional (e.g., a bidirectional DC / DC or charging pile-level DC / AC module) power converter (e.g., a buck-boost converter based on IGCT / IGBT or SiC MOSFET), supporting constant current / constant voltage output and capable of fast PWM response. Power conversion module 2 is mainly used for power conversion. Its control terminal is connected to control module 3 and receives commands from control module 3, thereby outputting controllable DC power to the battery. Its output terminal is connected to the positive and negative terminals of the battery.

[0021] The detection and protection module 4 is used to collect data required by the battery maintenance device in real time, such as battery voltage (including individual cell voltage, pack voltage, and total voltage), module temperature, output current of the power conversion module 2, relay status, CAN heartbeat, and BMS communication status signals. It then outputs the collected data to the control module 3, with its signal output terminal connected to the control module 3 for closed-loop control and status judgment. This module has built-in protection logic and can execute protection actions according to the instructions of the control module 3 or preset strategies, such as alarms (logs) and derating (reducing voltage). / reduce If the BMS actively issues a stop charging or rejection command, the device will immediately switch to a safe state (stop ripple and return to the steady-state current required by the BMS or power off).

[0022] The human-machine interaction module 5 is connected to the control module 3 through interfaces such as UART and SPI. It is used to receive user commands (such as mode selection and parameter setting), set parameters, and display the working status of the device (such as current mode, current, voltage, alarm information, etc.).

[0023] The control module 3, as the core processing unit of the device, preferably employs a DSP or FPGA, and is responsible for generating ripple references, PWM control, and communication logic. Its output (PWM output, etc.) is connected to the control terminal of the power conversion module 2, and its communication interface (such as a CAN bus interface, CP, PLC interface, etc.) is connected to the vehicle's BMS for communication handshake and command exchange. Its signal acquisition terminal (such as an ADC interface) is connected to the detection and protection module 4 to receive data from various sensors.

[0024] In this embodiment, the control module 3 is configured to control the device to operate in at least one of the following modes:

[0025] I. Dynamic Ripple Modulation Mode

[0026] In this mode, a high-frequency, low-amplitude AC ripple signal is superimposed on the power stage output of power conversion module 2 via hardware. This causes the battery to experience high-frequency current disturbances, achieving a maintenance effect. Simultaneously, since the current sampling frequency of the BMS is typically only 10-100Hz, accompanied by hardware filtering and averaging, this high-frequency component can be averaged by the BMS's sampling system. The BMS only identifies the stable average current, thus avoiding triggering overcurrent / abnormal protection. The principle is: under a constant current or constant voltage reference current... At the output terminal, a high-frequency, small-amplitude dynamic ripple current is directly superimposed through power stage hardware. This allows the battery to truly withstand high-frequency current disturbances, while the BMS only identifies the average current at the sampling and communication level, thus avoiding triggering abnormal protection.

[0027] Specifically, in dynamic ripple modulation mode, power conversion module 2 includes a ripple modulation branch. This ripple modulation branch is integrated into the main power conversion topology (e.g., by adding a disturbance path in the control loop). Its core consists of power devices driven by control module 3 (power device structures via addition or current superposition, such as MOSFETs) and a filter / damping network (such as an LC filter). This is used to generate an AC ripple signal, which modulates the reference current generated by power conversion module 2 at the power stage. The total output current is formed by superposition. The total output current Defined as:

[0028] (1)

[0029] in, The reference current (A) is a constant current determined by the BMS / charging protocol. The amplitude (A) of the AC ripple signal; The frequency (Hz) of the AC ripple signal should be selected, and the parameter value should meet the safety constraints of the device to ensure that the instantaneous current peak does not exceed the short-time overcurrent threshold allowed by the BMS. In this way, the battery terminal is subjected to the high-frequency pulsating current described by formula (1).

[0030] In dynamic ripple modulation mode, the frequency of the AC ripple signal The frequency range is 100 Hz to 5 kHz, which is much higher than the typical sampling bandwidth of a BMS, ensuring that it can be effectively averaged. A preferred frequency range is 500 Hz to 2 kHz to achieve the best balance between electrochemical response and filtering capability. Preferably, the amplitude of the AC ripple signal... Reference current value 1% to 10%, that is: 0.01 ≤ ΔI ≤ 0.10· For example, when At 50A, the superimposed ripple amplitude ∆I is ±0.5A to ±5A. This amplitude range provides effective electrochemical excitation to the battery while ensuring that the peak current does not exceed the short-time overcurrent protection threshold of the BMS, meeting the safety requirements of GB / T 18487.1. Even better, Further satisfy: ≤ min(0.1· , - - ),in As the reference current, The short-time overcurrent threshold for the vehicle's BMS. For safety margin (e.g., 0.1–1 A). The waveform of this AC ripple signal can be a sine wave or a filtered quasi-square wave to reduce harmonics and EMI.

[0031] The dynamic ripple modulation mode retains the electrochemical advantages of laboratory high-frequency pulse charging; the average current is within the allowable range of the BMS and meets the communication message requirements of GB / T27930; the peak current is still within the safety boundary defined by GB / T18487.1, ensuring safety compliance.

[0032] In this mode, a slope can be introduced to assess the impact on the controller / sensor, as shown in Equation (2):

[0033] (2)

[0034] In a practical example: Let =10A, =0.4A, =500Hz, then:

[0035] calculate =2×3.1416×500×0.4≈1256.6A / s. The instantaneous current change rate corresponding to this ripple reaches approximately 1256 A / s. In contrast, the maximum allowable current ramp-up rate (ramp_limit) of the BMS in new energy vehicles is typically 1–5 A / s, a difference of about three orders of magnitude.

[0036] Therefore, at the battery level, the electrochemical system of lithium-ion batteries is sensitive to millisecond-level dynamic current and can sense real ±0.4A high-frequency disturbances, thereby suppressing polarization, promoting ion diffusion, and inhibiting non-uniform growth of the SEI layer, thus improving cycle life.

[0037] At the BMS end, since its sampling frequency is usually only 10–100Hz, and after RC filtering and time averaging, the 500 Hz high-frequency component is completely filtered out at the sampling end. The BMS only recognizes it as a stable 10A constant current and will not trigger the abnormal protection logic.

[0038] This example fully demonstrates the engineering feasibility of the "dynamic ripple modulation mode": it can retain the electrochemical maintenance effect of high-frequency pulses, bypass the sampling and protection logic limitations of BMS, and meet the relevant constraints of GB / T 27930-2023 and GB / T18487.1-2023.

[0039] To ensure the accuracy of the ripple output, control module 3 is configured to perform dual closed-loop control: an outer constant current / constant voltage loop (slow loop) guarantees the average current. The inner fast current loop provides real-time error based on a sampling resistor or Hall sensor to correct the ripple phase and amplitude, ensuring the accuracy of the ripple waveform and avoiding uncontrolled spikes at the output. Specifically: the instantaneous total current output from the device to the battery is sampled in real time by a current sensor (such as a Hall sensor), and this is taken as the actual current value. The sampled actual current value is compared with the target current signal, i.e., in formula (1). The ideal waveform described is compared to generate an error signal (including amplitude and phase errors). Based on the error signal generated by the comparison, the control module 3 adjusts the PWM drive signal of the power device in the ripple modulation branch in real time to reduce the error between the actual current value and the target current signal, ensuring that the output waveform is consistent with the target.

[0040] In PWM design, high-resolution PWM (such as 16-bit) is used to reduce quantization errors. Ripple generation can be achieved by generating a sine wave in the DSP through LUT or Direct Digital Synthesis (DDS), and then adding it to a reference waveform for PWM scaling calculation.

[0041] In harmonic control, add a filter / damping network at the output, such as a small band-stop filter or select a smooth, approximate sine wave (avoiding sharp square waves), to reduce THD and EMI.

[0042] In this embodiment, during the communication handshake with the BMS, the maintenance device reports and confirms the reference current and allowable range (GB / T 27930 requirement) to the BMS; the average value of the superimposed ripple is strictly equal to the reference current approved by the BMS. The ripple amplitude is controlled within the range of 1%–10%, and the peak value is... = + The short-time overcurrent protection threshold of the BMS shall not be exceeded. Harmonic Distortion (THD) shall be measured and it shall be ensured that the THD and transients of the external conduction do not exceed the power quality and charging safety limits of GB / T18487.1 (if necessary, additional LC filters may be added to meet the standard).

[0043] II. Gradual Low-Frequency Command Mode

[0044] When external hardware cannot directly superimpose ripple, or when the BMS is sensitive to high-frequency fluctuations, a gradually changing low-frequency command mode can be selected. In this mode, the control module 3 sends a gradually changing current command with a frequency lower than its response bandwidth to the BMS through the communication interface. The change period of this command (several seconds) is much longer than the control period of the BMS, and a limiting algorithm is used to ensure that the single-step current change does not exceed the maximum allowable ramp-up rate of the BMS, thus enabling the BMS to smoothly follow the command and achieve equivalent low-frequency maintenance at the "visible" protocol layer. The principle is as follows: by utilizing the BMS's filtering and slow response characteristics for instantaneous high frequencies, by sending low-frequency, amplitude-limited smooth sine or similar curve commands, the BMS gradually follows within its own control bandwidth, thereby achieving equivalent low-frequency current disturbances.

[0045] In this mode, set the reference current. Based on this, sinusoidal or smooth curve perturbation signals are generated. :

[0046] (3)

[0047] Where f is the frequency of the slowly changing current command, ranging from 0.1 Hz to 0.5 Hz (corresponding to a period of 2–10 seconds, matching the BMS's response delay of 3–5 seconds). This frequency is lower than the BMS's response bandwidth, matching its response delay on the order of several seconds.

[0048] The amplitude of the gradually changing current command ranges from 1 A to 3 A. This amplitude range provides effective current ripple while avoiding rejection by the BMS due to excessively large command variations.

[0049] Key constraints:

[0050]

[0051] in (Unit: A / s) represents the measured maximum safe ramp rate of the BMS during the step test of current ramp / ramp.

[0052] In this embodiment of the application, before executing any mode, a current step command can be sent to the BMS and its response time can be measured. The current change rate of the BMS can be determined based on the response time and the current change during the response time. The maximum allowable ramp rate ramp_limit can be calculated based on the current change rate and the conservative coefficient.

[0053] Specifically: Under a safe low current condition (e.g., 10A), a current step command is issued to the BMS (e.g., stepping from a low current of 10A to 15A), and its response time ∆t (e.g., the time required for the current to reach 90% of the target value) is measured. The current change within this response time is... The calculated short-time current change rate (A / s), based on short-time current change rate and conservative coefficient (e.g., 0.8) Calculate the maximum allowable climb rate of the BMS. The It is used to constrain the single-step changes of all subsequent current commands, providing a key safety parameter for the subsequent limiting algorithm.

[0054] For example: if =10A, Achievement Time =4s, then =10 / 4=2.5A / s. (Assume...) =0.8, then =2.5 0.8 = 2A / s.

[0055] When generating discrete instructions, ensure that the single-step current change does not exceed ramp_limit × communication cycle to ensure that the BMS can execute smoothly.

[0056] In the gradually varying low-frequency command mode, the specific implementation of the amplitude limiting algorithm is as follows:

[0057] Communication period set to (For example, 200ms), according to the message refresh cycle defined in GB / T27930, discrete target points are generated in each cycle. :

[0058] (4), k represents a certain instruction issuance cycle.

[0059] Set the maximum current change per step ,in, This refers to the instruction issuance cycle; To determine the maximum permissible ramp rate within a cycle, the single-step current change within each command cycle is controlled by a limiting algorithm. and Constraints are imposed to avoid triggering BMS protection.

[0060] Actual current command value It can be calculated from the limiting function:

[0061] (5)

[0062] in, For the amplitude limiting function, The target current value for the kth cycle is calculated using the low-frequency sine wave formula, i.e., formula (4). This represents the maximum allowable change in current command value between two adjacent communication cycles. If the BMS refuses to execute or detects overvoltage / overtemperature, the system immediately reverts to a safe current and records the executed commands that were truncated for auditing and backtracking. This algorithm ensures that each command step size is limited within a safe range.

[0063] In the gradually changing low-frequency command mode, although the frequency at the battery end is low, it can still periodically change the polarization degree and ion concentration gradient during charging, playing a certain dynamic excitation role. Since the command changes are within the BMS's control bandwidth, the BMS can stably follow them and will not misjudge them as abnormalities.

[0064] This mode is implemented entirely based on the protocol layer, without requiring any changes to the hardware structure, making it suitable for vehicle maintenance or after-sales scenarios; it is fully compatible with the communication and security logic of the BMS, meeting national standards; and it can significantly improve battery consistency and degradation rate during vehicle operation.

[0065] In this embodiment, the detection and protection module 4 is also used to monitor the individual cell voltage, total voltage, module temperature, output current, and BMS communication status (such as CAN heartbeat and shutdown command) of the battery in real time. When an anomaly is detected, if any monitored value exceeds a preset safety threshold or a communication anomaly occurs (such as any individual cell voltage exceeding the limit, temperature exceeding the limit, or BMS communication interruption), this module will control the device to perform at least one of the following protective actions: reducing output power, stopping ripple superposition, restoring steady-state constant current, or cutting off output, to ensure the safety of the entire maintenance process. Furthermore, the device stores the abnormal events and corresponding timing data in log form, which can be exported.

[0066] The verification and testing process is as follows:

[0067] Bench test: Use the oscilloscope and power analyzer in the detection and protection module 4 to detect the ripple waveform, THD, and temperature rise at the output end; collect BMS messages to detect whether the BMS recognizes high-frequency components.

[0068] Compatibility matrix: Record the "visibility / alarm threshold / ramp_limit" of BMS for ripple on multiple vehicle models to form a support list.

[0069] Electrochemical verification: Compare the short-term EIS, polarization voltage, and long-term SOH evolution of constant current and constant current + ripple.

[0070] Example judgment criteria: A short-term decrease in EIS low-frequency polarization impedance ≥2% without BMS alarm is considered a preliminary pass; a long-term improvement in SOH ≥5% (compared with the control group) is considered a significant effect.

[0071] The embodiments of this application have the following significant beneficial effects:

[0072] It achieves safe maintenance under BMS supervision: Through two innovative modes, "dynamic ripple modulation" and "gradually changing low-frequency command", it cleverly avoids the protection logic of BMS and achieves battery pulse maintenance equivalent to laboratory results in a whole vehicle environment for the first time, solving the long-standing technical compatibility problem.

[0073] The maintenance effect is significant and flexible: the "Dynamic Ripple Modulation Mode" retains the excellent electrochemical maintenance effect of high-frequency pulses; the "Gradually Changing Low-Frequency Command Mode" provides extremely high vehicle model compatibility. The device can flexibly select the optimal mode according to different vehicle models to ensure maximum maintenance effect.

[0074] High safety and reliability: The device integrates comprehensive real-time monitoring and multi-level protection mechanisms, and ensures the safety of the entire link from command issuance to power output through BMS performance detection and closed-loop control, fully complying with national charging standards (GB / T 27930, GB / T 18487.1).

[0075] Highly engineered and easy to promote: The device has a clear structure, well-defined methods, and provides specific verification means, making it very suitable for large-scale promotion and application in vehicle manufacturer maintenance systems, 4S stores, and professional battery maintenance organizations, effectively extending battery life and reducing users' total life cycle costs.

[0076] Based on the same inventive concept, embodiments of this application also provide a battery maintenance method for new energy vehicles. Applied to the aforementioned battery maintenance device, such as... Figure 2 As shown, it includes the following steps:

[0077] In step 101, a communication connection is established with the vehicle BMS (in accordance with GB / T 27930), and the preset parameters of the vehicle BMS are read; these parameters include at least the short-term overcurrent threshold, the sampling period, and the communication period;

[0078] In step 102, a step current command is sent to the vehicle BMS and the response is measured to calculate the short-time current change rate. Based on the current change rate and a conservative coefficient, the maximum permissible ramp rate is calculated.

[0079] In step 103, the operating mode is selected based on the current state of the battery and the characteristics of the vehicle BMS. The operating mode can be selected by the user through the human-machine interface. The operating mode includes dynamic ripple modulation mode and gradual low-frequency command mode.

[0080] When the dynamic ripple modulation mode is selected, an AC ripple signal is generated through the ripple modulation branch in the power conversion module 2. This signal is superimposed with the reference current generated by the power conversion module 2 to form the total output current, which is applied to the battery. At the same time, the amplitude and frequency of the AC ripple signal should meet the pre-calculated safety constraints.

[0081] When the slow-varying low-frequency command mode is selected, a slow-varying current command with a frequency lower than its response bandwidth is sent to the BMS through the communication interface, and a limiting algorithm is used to ensure that the single-step current change does not exceed the maximum allowable ramp-up rate of the BMS.

[0082] During maintenance, various parameters are monitored in real time, and protective actions are executed and logs are recorded when anomalies occur.

[0083] In dynamic ripple modulation mode, a dual closed-loop control can be employed, including: an outer loop control (slow loop) for steady-state regulation of the reference current, and an inner loop control (fast current loop) for precise control of the amplitude and phase of the AC ripple signal to ensure waveform quality. Furthermore, the sampling bandwidth of the inner loop control is not less than 5× , For the maximum modulation frequency that the device can generate and effectively control, the PWM update rate satisfies the following requirements: The control requirements are to ensure ripple tracking accuracy and system stability.

[0084] Preferably, the method of this embodiment may further include an effect verification step: evaluating the maintenance effect by measuring the battery's electrochemical impedance spectroscopy (EIS) and changes in battery health. Specifically, the method observes whether the low-frequency polarization impedance decreases (e.g., ≥2%) by measuring the battery's EIS as a short-term effect determination; and confirms whether capacity decay is significantly delayed (e.g., SOH improvement ≥5%) by long-term tracking of changes in battery health (SOH) and comparing it with the constant current charging control group, thus serving as the final evaluation basis for the long-term maintenance effect.

[0085] The method described in this application embodiment monitors the battery and BMS status in real time during battery maintenance and executes a safety rollback procedure when an anomaly occurs.

[0086] 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.

[0087] 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.

[0088] 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 device for a new energy vehicle, characterized in that, The device comprises a power input module, a control module, a power conversion module, a detection and protection module, and a human-computer interaction module. The power input module is used for accessing an external power supply and providing stable direct current, and the output end thereof is connected to the input end of the power conversion module. The power conversion module is used for power conversion and outputs controllable direct current to a battery, and the control end thereof is connected to the control module. The control module is connected to the control end of the power conversion module through the output end thereof, and is connected to the vehicle BMS through the communication interface thereof, and is connected to the detection and protection module through the signal acquisition end thereof. The control module is configured to control the device to work in at least one of the following modes: A dynamic ripple modulation mode: on the power level output of the power conversion module, a high-frequency low-amplitude alternating ripple signal is superimposed by hardware, so that the battery end bears high-frequency current disturbance, and the high-frequency component of the alternating ripple signal can be averaged by the sampling system of the BMS; A slowly-varying low-frequency instruction mode: a slowly-varying current instruction with a frequency lower than the response bandwidth of the BMS is issued to the BMS through the communication interface, and a limiting algorithm is used to ensure that the single-step current change is not greater than the maximum allowed climbing rate of the BMS; The detection and protection module is used for real-time acquisition of required data and output to the control module, and performs protection actions according to the instructions of the control module or preset strategies; The human-computer interaction module is connected to the control module, and is used for receiving user instructions, setting parameters, and displaying the working state of the device. In the dynamic ripple modulation mode, the frequency range of the high-frequency low-amplitude alternating ripple signal is 100 Hz to 5 kHz, and the amplitude is 1% to 10% of the reference current value. In the dynamic ripple modulation mode, the power conversion module comprises a ripple modulation branch. The specific implementation of the limiting algorithm is as follows: The ripple modulation branch includes a power device driven by the control module and a filter / damping network for generating the alternating ripple signal, which is superimposed with the reference current generated by the power conversion module to form a total output current ; the total output current is defined as: wherein, is a reference constant current; is an amplitude of the AC ripple signal; is a frequency of the AC ripple signal; The control module is configured to perform closed-loop control, including: Setting single step maximum current change amount wherein, is a command issuance period, is a maximum allowed climb rate within the period; Actual current command value issued Is: wherein, is a clipping function, is a target current value of the kth period, is a maximum change amount of the current command value allowed to be issued between the adjacent two communication periods.

2. The battery maintenance apparatus of claim 1, wherein Real-time sampling of the instantaneous total current output by the device to the battery as the actual current value; Comparing the actual current value with the target current signal; according to the error signal generated by the comparison, the driving signal of the power device in the ripple modulation branch is adjusted in real time to reduce the error between the actual current value and the target current signal. In the slowly-varying low-frequency instruction mode, the frequency range of the slowly-varying current instruction is 0.1 Hz to 0.5 Hz, and the amplitude range is 1 A to 3 A.

3. The battery maintenance apparatus of claim 1, wherein Before executing any mode, the device is configured to issue a current step instruction to the BMS and measure the response time, determine the current change rate of the BMS according to the current change in the response time, and calculate the maximum allowed climbing rate based on the current change rate and a conservative coefficient.

4. The battery maintenance apparatus of claim 1, wherein The detection and protection module monitors the single-cell voltage, total voltage, module temperature, output current, and BMS communication state of the battery in real time, and controls the device to perform at least one of the following protection actions when an abnormality is detected: reducing the output power, stopping ripple superposition, restoring the steady-state constant current, or cutting off the output.

5. The battery maintenance apparatus of claim 1, wherein The device comprises:

6. A battery maintenance method for a new energy vehicle, applied to the battery maintenance device according to any one of claims 1 to 5, characterized in that, establishing a communication connection with the vehicle BMS, and reading the preset parameters of the vehicle BMS; ​ issuing step current command to vehicle BMS and measuring response to calculate short time current rate of change, calculating maximum allowed ramp rate based on the current rate of change and a conservative coefficient; selecting operation mode according to current state of battery and characteristics of vehicle BMS, the operation mode including dynamic ripple modulation mode and slowly varying low frequency command mode; when dynamic ripple modulation mode is selected, generating AC ripple signal through ripple modulation branch in power conversion module, superimposing the AC ripple signal with reference current generated by the power conversion module to form total output current; when slowly varying low frequency command mode is selected, issuing slowly varying current command with frequency lower than response bandwidth of BMS to BMS through communication interface, and ensuring single step current change does not exceed maximum allowed ramp rate of BMS through limiting algorithm.

7. The method of claim 6, wherein, double closed loop control is adopted in the dynamic ripple modulation mode; the double closed loop control includes outer loop control for steady state regulation of the reference current and inner loop control for accurate control of amplitude and phase of the AC ripple signal.

8. The method of claim 6, wherein, the method further includes evaluating maintenance effect by measuring electrochemical impedance spectrum of the battery and change of state of health of the battery.

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