Battery current zero position control method and system in pure heating mode

Abstract

The invention provides a battery current zero position control method and system in a pure heating mode, the method is applied to a battery management system, and the battery management system controls a charging device to supply power to a heating assembly and vehicle accessories when a main positive relay and a main negative relay of a battery are closed. The method comprises the following steps: when a battery management system enters a pure heating mode, acquiring an end current measurement value of a battery pack and an actual output current value of charging equipment in real time, and calculating a current deviation value between the end current measurement value and a preset zero target interval; calculating a dynamic response factor of the charging equipment in real time based on the ratio of the current request adjustment amount to the actual output current variation of the charging equipment in the historical control period, and calculating a current request correction value of the current control period according to the current deviation amount and the dynamic response factor; and updating a request current instruction sent to the charging equipment based on the current request correction value, wherein the driving end current measurement value converges to a preset zero target interval.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle battery management technology, specifically relating to a method and system for zero-point control of battery current in pure heating mode. Background Technology

[0002] With the popularization of new energy vehicles, the performance and safety of power batteries in low-temperature environments have received widespread attention. Under low-temperature conditions, the charge and discharge capacity of lithium-ion batteries decreases significantly, especially low-temperature charging, which easily leads to lithium plating on the negative electrode, severely affecting battery life and even causing safety accidents. Therefore, a battery thermal management system is essential for heating the battery at low temperatures. One of the mainstream heating methods currently is to utilize external charging equipment to power the battery pack through a positive temperature coefficient (PTC) heater or waste heat from the motor. In traditional pure heating mode, to ensure battery safety, the main positive and negative relays of the battery are usually disconnected, physically disconnecting the battery pack from the high-voltage bus, with the charging pile directly supplying power to the heating components.

[0003] However, with the development of vehicle electronic and electrical architecture and the improvement of user experience requirements, new technical requirements have emerged: maintaining the battery main relay closed during the heating process. This is mainly to maintain the normal operation of high-voltage accessories in the vehicle and reduce the lifespan loss and engagement noise caused by frequent opening and closing of the relay. However, in the architecture with the main relay closed, the charging pile, battery pack, heating components, and vehicle accessories are electrically connected in parallel. According to Kirchhoff's current law, the current flowing into / out of the battery is equal to the difference between the charging pile's output current and the current consumed by all loads. Since the power of the heating components fluctuates non-linearly with temperature, and the load of vehicle accessories also fluctuates, coupled with the lag and error in the charging pile's response to current commands, it is very easy for the charging pile's output current to mismatch with the load current.

[0004] If the charging pile's output current exceeds the load current, the excess current will flow into the battery, posing a risk of lithium plating during low-temperature charging. Conversely, if the charging pile's output current is less than the load current, the battery will be forced to discharge, resulting in unnecessary energy loss. Existing control methods typically employ simple PID feedback regulation, but when faced with complex operating conditions such as large response lag in charging piles and sudden load changes, they are prone to problems such as over-regulation, current oscillation, or slow convergence speed, failing to meet the requirements for high-precision zero-position control. Summary of the Invention

[0005] This invention proposes a battery current zero-point control method and system in pure heating mode, which solves the problem that existing technologies cannot effectively control the battery terminal current while keeping the main positive and main negative relays closed throughout the process, thus damaging the battery cell.

[0006] To address the aforementioned technical problems, this invention provides a battery current zero-point control method in pure heating mode, applied to a battery management system. The battery management system controls the charging equipment to supply power to the heating components and vehicle accessories when the main positive and main negative battery relays are closed. The method includes the following steps: Step S1: When the battery management system enters the pure heating mode, the terminal current measurement value of the battery pack and the actual output current value of the charging device are obtained in real time, and the current deviation between the terminal current measurement value and the preset zero target range is calculated. Step S2: Based on the ratio of the current request adjustment amount to the actual output current change of the charging device within the historical control cycle, calculate the dynamic response factor of the charging device in real time, and calculate the current request correction value for the current control cycle according to the current deviation amount and the dynamic response factor. Step S3: Update the request current command sent to the charging device based on the current request correction value, and drive the terminal current measurement value to converge to the preset zero target range.

[0007] Preferably, the real-time calculation of the dynamic response factor of the charging device in step S2 includes the following steps: Step S201: Construct a length of N The sliding time window, in the first i Each control cycle records the requested current command issued by the battery management system. and the actual output current of the charging device collected Calculate the dynamic response factor K : ; ; In the formula, Exponentially decaying weights; It is the attenuation factor; This is the control cycle index within the sliding window. ; For the first The actual output current change over each cycle; For the first The change in requested current over each cycle; Step S202: In the first i+ In one control cycle, if the cumulative value of the requested current change is less than the minimum change threshold, the charging device is determined to be in a steady state, and the dynamic response factor of the previous cycle remains unchanged; otherwise, the dynamic response factor is recalculated.

[0008] Preferably, step S2, which calculates the current request correction value for the current control cycle based on the current deviation and the dynamic response factor, includes the following steps: calculating the current request correction value for the current control cycle; when the dynamic response factor is less than a preset response threshold, determining that the charging device is in a weak response state; automatically increasing the waiting time of the control cycle or decreasing the gain coefficient of the current request correction value using a preset adaptive adjustment algorithm; and updating the current request correction value for the current control cycle. The expression for the current request correction value is: ; In the formula, Request a correction value for the current in the current control cycle; This is the gain coefficient; This is the measured value of the terminal current; It is the center value of the zero-position target interval.

[0009] Preferably, the step of calculating the current request correction value for the current control cycle using a preset adaptive adjustment algorithm includes the following steps: determining the polarity of the terminal current measurement value; if the terminal current measurement value is negative and exceeds the charging boundary of the preset zero target range, then the battery is determined to be in a charging trend; and the first gain coefficient is selected to calculate the current request correction value to perform a downward adjustment. If the measured terminal current value is positive and exceeds the discharge boundary of the preset zero target range, the battery is determined to be in a discharge trend. The second gain coefficient is used to calculate the current request correction value to perform an upward adjustment correction. The expression for the first gain coefficient is: ; In the formula, The first gain coefficient; The basic gain coefficient; This refers to the temperature sensitivity coefficient. For reference temperature; This represents the lowest individual cell temperature in the battery pack. The expression for the second gain coefficient is: ; In the formula, This is the second gain coefficient; The basic gain coefficient; and .

[0010] Preferably, in step S3, the requested current command sent to the charging device is updated in conjunction with a feedforward compensation mechanism, the expression of which is: ; In the formula, This is a request for current sent to the charging device; This is the cumulative amount of the requested correction value for the current. The feedforward compensation component is obtained by summing the real-time power demand of the heating components and the real-time current consumption of the vehicle accessories.

[0011] Preferably, step S1, which dynamically adjusts the preset zero-point target range based on battery temperature, includes the following steps: pre-stores a temperature-current mapping table in the memory of the battery management system. The temperature-current mapping table defines multiple temperature ranges and the allowable charging current boundary value corresponding to each temperature range. In the temperature-current mapping table, as the temperature value of the temperature range increases, the absolute value of the allowable charging current boundary value corresponding to the temperature increases in a stepwise manner. The lowest cell temperature of the battery pack is monitored in real time. The allowable charging current boundary value corresponding to the lowest cell temperature is found in the temperature-current mapping table. The found allowable charging current boundary value is set as the lower limit of the preset zero-position target range within the current control cycle.

[0012] Preferably, before sending the request current command to the charging device in step S3, trend prediction correction is further included, comprising the following steps: Step a: Establish the state vector of the current state model ,in This is the measured value of the terminal current. The rate of change of current; Step b: In each control cycle, perform the Kalman filter prediction and update steps to obtain the optimal estimate of the current change rate. ; Step c: When the direction of the current change rate points to the zero target range, and the absolute value of the current change rate exceeds the preset trend threshold, initiate trend prediction correction: Calculate the predicted convergence time : ; In the formula, This is the measured value of the terminal current; The center value of the zero-position target interval; like The output of the current request correction value will be temporarily suspended for a period of time: ; In the formula, This is the convergence time threshold; Maximum suspension time; Step d: During the suspension period, continuously monitor the current change. If the current change trend reverses or the current exceeds the safety boundary, immediately restore the correction value output.

[0013] Preferably, the method further includes an abnormal circuit breaker protection mechanism, comprising the following steps: Step A: Define the three-level protection thresholds and corresponding fault counters: (1) Level 1 warning: If First protection threshold, set first fault count threshold, increase first gain coefficient. Generate early warning logs; (2) Level 2 alarm: If The second protection threshold sets a second fault count threshold, limiting the increment of the requested current. If the value is ≤0, an alarm signal is generated; (3) Level 3 circuit breaker: If Set the third protection threshold, set the third fault count threshold, send a stop command, disconnect the main relay, and record the fault code; Step B: Set the update rules for the fault counter: Current measurement value at the detection terminal in each control cycle ,like If the current is less than the corresponding level's current threshold, increment the corresponding level's fault counter by 1; if If the current threshold is greater than or equal to the corresponding level, then the fault counter for the corresponding level... Employ a decay-to-zero strategy: ; Step C: Each level of protection is independent of the others; when a higher-level protection is triggered, it automatically overrides the lower-level protection measures. Step D: After the Level 3 fuse is triggered, the system enters a fault-locked state, which can be restored by manual reset or by powering down and restarting the vehicle. Step E: Record the timestamp, current value, and temperature value of each protection trigger for subsequent fault analysis.

[0014] The present invention also provides a battery current zero-point control system in pure heating mode, which is based on the above-mentioned battery current zero-point control method in pure heating mode. The system includes: a data acquisition module, a zero-point deviation calculation module, a dynamic response factor calculation module, a current request correction calculation module, the instruction update and sending module, and a control logic management module. The data acquisition module: collects the terminal current measurement value of the battery pack and the actual output current value of the charging equipment in real time; The zero-position deviation calculation module calculates the current deviation based on the measured terminal current value of the battery pack and the preset zero-position target range. The dynamic response factor calculation module calculates the dynamic response factor of the charging device in real time based on the ratio of the current request adjustment amount to the actual output current change of the charging device within the historical control cycle. The current request correction calculation module calculates the current request correction value for the current control cycle based on the current deviation and the dynamic response factor. The instruction update and sending module updates the current request instruction sent to the charging device based on the calculated current request correction value. The control logic management module manages the control logic of the entire pure heating mode, including determining the entry and exit times of the pure heating mode and coordinating the execution order of the above modules.

[0015] Preferably, the system further includes a status monitoring and safety protection module, which monitors the system's operating status in real time. If the system status is abnormal, it exits zero-position control and issues an alarm.

[0016] The beneficial effects of the present invention include at least the following: 1. By acquiring the terminal current measurement value of the battery pack and the actual output current value of the charging equipment in real time, the current deviation can be accurately calculated. This real-time monitoring mechanism enables the system to respond quickly to current changes and ensure that the current of the battery pack is always within the preset zero target range. 2. Based on the ratio of the current request adjustment amount to the actual output current change of the charging equipment within the historical control cycle, the dynamic response factor of the charging equipment is calculated, so that the system can adjust according to the actual dynamic characteristics of the charging equipment, avoiding inaccurate current control caused by equipment response delay or too fast. 3. By calculating the current request correction value and updating the request current command sent to the charging device, the current measurement value at the drive end converges to the preset zero target range, which can effectively reduce current fluctuations and improve the stability and reliability of the system. 4. This method can adapt to the dynamic characteristics of different charging devices. Even when the device is aging or the environment changes, it can adjust the control strategy through real-time calculation of dynamic response factors to maintain the stable operation of the system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit topology of the battery system in an embodiment of the present invention; Figure 2 This is a flowchart of the battery current zero-point control method in an embodiment of the present invention; Figure 3 This is a structural block diagram of the battery current zero-point control system in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0019] like Figure 1 As shown, this embodiment of the invention provides a typical circuit topology for a battery system. This circuit topology includes components such as a battery pack, a battery management system (BMS), charging equipment, heating components, vehicle accessories, a main positive relay, a main negative relay, and a current sensor.

[0020] In this circuit topology, the battery pack is connected to the external circuit via a main positive relay and a main negative relay. The charging equipment can charge the battery pack and also supply power to the heating components and vehicle accessories. Current sensors are used to detect the current flowing into or out of the battery pack, where the charging current is defined as negative current and the discharging current as positive current.

[0021] In pure heating mode, the battery management system keeps the main positive and main negative relays closed, and the charging equipment mainly supplies power to the heating components to heat the battery. At this time, it is necessary to precisely control the output current of the charging equipment so that the current flowing into or out of the battery pack is maintained within the preset zero-point target range.

[0022] like Figure 2 As shown, this embodiment of the invention provides a battery current zero-point control method in pure heating mode, which is applied to the battery management system of an electric vehicle. Specifically, it includes the following steps: Step S1: When the battery management system enters the pure heating mode, the terminal current measurement value of the battery pack and the actual output current value of the charging device are obtained in real time, and the current deviation between the terminal current measurement value and the preset zero target range is calculated.

[0023] Specifically, when the battery pack is connected to the charging equipment, the battery management system first enters the slow charging process and determines whether it needs to enter the pure heating mode. The determination is mainly based on the cell temperature. If the cell temperature is lower than the preset heating start temperature threshold, it is determined that it needs to enter the pure heating mode; otherwise, it enters the charging and heating mode or the normal charging mode.

[0024] Once the pure heating mode is confirmed, the battery management system keeps the main positive and main negative relays closed and sends initial request parameters to the charging equipment. Initial request voltage. Set to the maximum allowable voltage of the battery pack Including the preset margin, the initial requested current Set as the current required by the heating component Current consumption of vehicle accessories The sum of these factors causes the battery pack to begin heating up.

[0025] The battery management system collects the terminal current measurement value of the battery pack in real time through a current sensor and compares the terminal current measurement value with a preset zero-point target range. In this embodiment of the invention, the zero-point target range is set to -1A to +1A. This parameter can be calibrated and adjusted according to actual needs, wherein the discharge current is positive and the charging current is negative.

[0026] If the terminal current measurement value Satisfy -1A≤ If the current is ≤1A, it is determined that the current is within the zero target range, and the system continues to maintain the current requested parameters and continue monitoring; if the terminal current measurement value .... If the current exceeds the zero target range, a current request correction is required.

[0027] Step S2: Based on the ratio of the current request adjustment amount to the actual output current change of the charging device within the historical control cycle, calculate the dynamic response factor of the charging device in real time, and calculate the current request correction value for the current control cycle based on the current deviation and the dynamic response factor.

[0028] Specifically, if If the current request is ≤-1A and lasts for 100ms, it is determined that the charging request current is too high, the battery is in a charging trend and exceeds the threshold. In this case, a downward adjustment is performed to reduce the requested current, specifically: ; in, To correct the step size, it is set to 1A in this embodiment of the invention.

[0029] like If the current request is ≥1A and lasts for 100ms, it is determined that the charging request current is too low, the battery is in a discharging trend, and the current exceeds the threshold. In this case, an upward adjustment is performed to increase the requested current, specifically: .

[0030] To adapt to the response characteristics of different charging devices, this embodiment of the invention constructs a sliding time window to record the sequence of requested current commands issued by the battery management system and the sequence of actual output currents of the charging devices. The dynamic response factor is obtained by calculating the ratio of the change in the actual output current of the charging devices to the change in the requested current commands within the sliding time window. Specifically, it includes the following steps: Step S21: Construct a length of N Sliding time window, NThe value range is 5-20 control cycles, with a preferred value of 10 control cycles. The duration of each control cycle is 50-200ms, with a preferred value of 100ms. Step S22: In the first i Each control cycle records the requested current command issued by the battery management system. and the actual output current of the charging device collected Calculate the dynamic response factor K : ; ; In the formula, Exponentially decaying weights; The attenuation factor has a value range of 0.8-0.95, with a preferred value of 0.9. This is the control cycle index within the sliding window. ; For the first The actual output current change over each cycle; For the first The change in requested current over each cycle; Step S23: In the first i+ One control cycle, when the cumulative value of the requested current change... Less than the minimum change threshold When the charging device is in a steady state, the dynamic response factor of the previous cycle remains unchanged. The value range is 0.1-0.5A, with a preferred value of 0.2A; otherwise, the dynamic response factor is recalculated. Step S24: Calculate the dynamic response factor K Apply boundary limiting; the limiting range is: ,in The value range is 0.1-0.3, with a preferred value of 0.2; The value range is 1.5-2.5, with a preferred value of 2.0; when K When the amplitude exceeds the limit, the corresponding boundary value is used.

[0031] Considering that low-temperature charging poses a higher risk of cell damage than low-temperature discharging, this embodiment of the invention employs an asymmetric gain coefficient design. When the battery is in a charging trend, a first gain coefficient is used to calculate the current request correction value to quickly suppress the charging current; when the battery is in a discharging trend, a second gain coefficient is used to calculate the current request correction value. The expression for the first gain coefficient is: ; In the formula, The first gain coefficient; The base gain coefficient has a value range of 1.5-3.0, with a preferred value of 2.0. The value is the temperature sensitivity coefficient, ranging from 0.5 to 1.5, with a preferred value of 1.0. For reference temperature, the value is taken as 25℃; This represents the lowest individual cell temperature in the battery pack.

[0032] When the lowest individual cell temperature of the battery pack At temperatures below -10°C, The maximum value of 4.0 is set to achieve rapid suppression of extremely low temperature charging.

[0033] The expression for the second gain coefficient is: ; In the formula, This is the second gain coefficient; The base gain coefficient has a value range of 0.5-1.5, with a preferred value of 1.0. and This design ensures that the adjustment force in the charging direction is always greater than that in the discharging direction, thus prioritizing the protection of the battery cell from damage caused by low-temperature charging.

[0034] An adaptive adjustment algorithm is provided in this embodiment of the invention, based on the dynamic response factor. K The value range is determined by automatically increasing the waiting time of the control cycle or decreasing the gain coefficient of the current request correction value to avoid oscillations caused by over-adjustment. This is based on the dynamic response factor. K The numerical range of the dynamic response factor is used to divide the response state of the charging device into four levels. Table 1 shows the correspondence between the dynamic response factor and the response state of the charging device.

[0035] Table 1. Correspondence between dynamic response factor and charging device response state in, The basic control cycle has a range of 50-200ms, with a preferred value of 100ms. This refers to the actual control cycle.

[0036] when K When the value is greater than 1.2, it is determined that the charging equipment has an overshoot risk. At this time, the step size of the current request correction value is reduced to 70% of the original step size. If the charging equipment is in a severely weak response state for 5 consecutive control cycles, the weak response event is recorded and a diagnostic code is generated for subsequent maintenance reference.

[0037] The formula for calculating the current request correction value is: ; In the formula, Request a correction value for the current in the current control cycle; This is the gain coefficient; This is the measured value of the terminal current; It is the center value of the zero-position target interval.

[0038] The correction value limit is ,in The maximum correction step size for a single cycle is 0.5-2.0A, with a preferred value of 1.0A.

[0039] Step S3: Update the request current command sent to the charging device based on the current request correction value, and the current measurement value at the drive end converges to the preset zero target range.

[0040] Specifically, to improve the response speed of current control, this embodiment of the invention incorporates a feedforward compensation mechanism to update the requested current command. Feedforward compensation component The current request is obtained by summing the real-time power demand of the heating components and the real-time current consumption of the vehicle accessories. The final current request command is: ; In the formula, This is a request for current sent to the charging device; This is the cumulative amount of the requested correction value for the current.

[0041] Cumulative limit is ,in The maximum cumulative correction value ranges from 5 to 20A, with a preferred value of 10A.

[0042] To achieve precise control under different temperature conditions, this embodiment of the invention pre-stores a temperature-current mapping table as shown in Table 2 in the memory of the battery management system. The mapping table is based on the lowest individual cell temperature of the battery pack. As input, output the corresponding allowable charging current boundary value. Its negative value indicates the charging direction.

[0043] Table 2 Temperature-Current Mapping Table This mapping table defines multiple temperature ranges and the corresponding allowable charging current boundary values ​​for each temperature range. As the temperature value of a temperature range increases, the absolute value of the corresponding allowable charging current boundary value increases in a stepwise manner.

[0044] The system monitors the lowest individual cell temperature of the battery pack in real time, looks up the allowable charging current boundary value corresponding to that temperature in the temperature-current mapping table, and sets it as the lower limit of the preset zero-position target range within the current control cycle.

[0045] Meanwhile, to suppress overshoot oscillation, this embodiment of the invention also includes a trend prediction correction step before sending the requested current command to the charging device. The trend prediction correction employs a Kalman filter-based method and specifically includes the following steps: Step a: Establish the state vector of the current state model ,in This is the measured value of the terminal current. The rate of change of current; Step b: In each control cycle, perform the Kalman filter prediction and update steps to obtain the optimal estimate of the current change rate. ; Step c: When the direction of the current change rate points to the zero target range, and the absolute value of the current change rate exceeds the preset trend threshold, initiate trend prediction correction: Calculate the predicted convergence time : ; In the formula, This is the measured value of the terminal current; The center value of the zero-position target interval; like The output of the current request correction value will be temporarily suspended for a period of time: ; In the formula, This is the convergence time threshold; Maximum suspension time; Step d: During the suspension period, continuously monitor the current change. If the current change trend reverses or the current exceeds the safety boundary, immediately restore the correction value output.

[0046] To ensure system security, an abnormal circuit breaker protection mechanism is also set up. The abnormal circuit breaker protection mechanism adopts a multi-level protection strategy, as follows: Step A: Define the three-level protection thresholds and corresponding fault counters: (1) Level 1 warning: If <-3A, set the fault count threshold N 1=10, increasing the first gain coefficient Up to 1.5 times, generate an early warning log; (2) Level 2 alarm: If <-5A, set the fault counting threshold N 2=5, limiting the requested current increment. If the value is ≤0, an alarm signal is generated; (3) Level 3 circuit breaker: If <-8A, set the fault count threshold N 3=3, send a stop command, disconnect the main relay, and record the fault code; Step B: Set the update rules for the fault counter: Current measurement value at the detection terminal in each control cycle ,like If the current is less than the corresponding level's current threshold, the fault counter for that level is incremented by 1; if If the current threshold is greater than or equal to the corresponding level, then the fault counter for that level... Employ a decay-to-zero strategy: ; Step C: Each level of protection is independent of the others; when a higher-level protection is triggered, it automatically overrides the lower-level protection measures. Step D: After the Level 3 fuse is triggered, the system enters a fault-locked state, which can only be restored after manual reset or vehicle power-off and restart. Step E: Record the timestamp, current value, temperature value, and other information for each protection trigger for subsequent fault analysis.

[0047] The system continues to execute the above judgment and adjustment steps, controlling the inflow and outflow current of the battery cell in the pure heating mode to be within the preset zero target range, until the battery temperature rises to the preset threshold, then exits the pure heating state and enters the charging and heating mode, finally completing the charging.

[0048] like Figure 3 As shown, this embodiment of the invention also provides a battery current zero-point control system in pure heating mode. This system is based on the above method and includes the following modules: Data acquisition module: This module connects to the current sensor and the communication interface of the charging equipment. It is responsible for acquiring the terminal current measurement value of the battery pack and the actual output current value of the charging equipment in real time, and transmitting the acquired data to other modules for processing.

[0049] Zero-point deviation calculation module: This module receives the terminal current measurement value transmitted by the data acquisition module and calculates the current deviation based on the preset zero-point target range. When the terminal current measurement value exceeds the zero-point target range, this module outputs the corresponding current deviation.

[0050] Dynamic response factor calculation module: This module constructs a sliding time window to record the sequence of request current commands issued by the battery management system and the actual output current sequence of the charging equipment within the historical control cycle. By calculating the ratio of the changes in the two, the dynamic response factor of the charging equipment is calculated in real time.

[0051] Current Request Correction Calculation Module: This module receives the current deviation output from the zero-point deviation calculation module and the dynamic response factor output from the dynamic response factor calculation module. It uses an adaptive adjustment algorithm to calculate the current request correction value for the current control cycle and implements asymmetric gain coefficient design and trend prediction correction functions.

[0052] Command update and sending module: This module receives the current request correction value output by the current request correction calculation module, updates the request current command sent to the charging device in conjunction with the feedforward compensation mechanism, and sends the command to the charging device through the communication interface.

[0053] Control Logic Management Module: This module manages the control logic of the entire pure heating mode, including determining the entry and exit conditions of the pure heating mode, coordinating the execution order of the above modules, and ensuring the correct execution of the control process.

[0054] Status monitoring and safety protection module: This module monitors the system's operating status in real time and implements an abnormal fuse protection mechanism. When the measured terminal current value is detected to be less than the negative safety threshold for multiple consecutive control cycles, the zero-position control is deemed to have failed, triggering an alarm and sending a shutdown command to the charging equipment.

[0055] All of the above modules can be integrated into the main controller of the battery management system and implemented through software, without the need for additional hardware costs.

[0056] This invention achieves high-precision zero-point control of battery current in pure heating mode through the synergistic effects of exponentially weighted dynamic response factor estimation, temperature-correlated asymmetric gain design, multi-level weak response processing strategy, Kalman filter-based trend prediction correction, and multi-level fuse protection mechanism. Compared with existing technologies, the control system of this invention can adapt to the differences in response characteristics of different brands and models of charging equipment; it can prioritize the protection of the battery from lithium plating damage during charging in extremely low temperature environments; the control process has a fast convergence speed and no obvious oscillation; the system has a complete hierarchical protection mechanism and high safety and reliability.

[0057] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; only preferred embodiments of the present invention are illustrated. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. As long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0058] It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for controlling zero-point battery current in pure heating mode, characterized in that, The method, applied to a battery management system, controls the charging equipment to supply power to the heating components and vehicle accessories when the main positive relay and the main negative relay are closed, includes the following steps: Step S1: When the battery management system enters the pure heating mode, the terminal current measurement value of the battery pack and the actual output current value of the charging device are obtained in real time, and the current deviation between the terminal current measurement value and the preset zero target range is calculated. Step S2: Based on the ratio of the current request adjustment amount to the actual output current change of the charging device within the historical control cycle, calculate the dynamic response factor of the charging device in real time, and calculate the current request correction value for the current control cycle according to the current deviation amount and the dynamic response factor. Step S3: Update the request current command sent to the charging device based on the current request correction value, and drive the terminal current measurement value to converge to the preset zero target range.

2. The battery current zero-point control method in pure heating mode according to claim 1, characterized in that: The real-time calculation of the dynamic response factor of the charging device in step S2 includes the following steps: Step S201: Construct a length of N The sliding time window, in the first i Each control cycle records the requested current command issued by the battery management system. and the actual output current of the charging device collected Calculate the dynamic response factor K : ； ； In the formula, Exponentially decaying weights; It is the attenuation factor; This is the control cycle index within the sliding window. ; For the first The actual output current change over each cycle; For the first The change in requested current over each cycle; Step S202: In the first i+ In one control cycle, if the cumulative value of the requested current change is less than the minimum change threshold, the charging device is determined to be in a steady state, and the dynamic response factor of the previous cycle remains unchanged; otherwise, the dynamic response factor is recalculated.

3. The battery current zero-point control method in pure heating mode according to claim 1, characterized in that: Step S2, calculating the current request correction value for the current control cycle based on the current deviation and the dynamic response factor, includes the following steps: calculating the current request correction value for the current control cycle; when the dynamic response factor is less than a preset response threshold, determining that the charging device is in a weak response state; automatically increasing the waiting time of the control cycle or decreasing the gain coefficient of the current request correction value using a preset adaptive adjustment algorithm; and updating the current request correction value for the current control cycle. The expression for the current request correction value is: ； In the formula, Request a correction value for the current in the current control cycle; This is the gain coefficient; This is the measured value of the terminal current; It is the center value of the zero-position target interval.

4. The battery current zero-point control method in pure heating mode according to claim 3, characterized in that: The method of calculating the current request correction value for the current control cycle using a preset adaptive adjustment algorithm includes the following steps: determining the polarity of the terminal current measurement value; if the terminal current measurement value is negative and exceeds the charging boundary of the preset zero target range, then determining that the battery is in a charging trend; and using a first gain coefficient to calculate the current request correction value to perform a downward adjustment. If the measured terminal current value is positive and exceeds the discharge boundary of the preset zero target range, the battery is determined to be in a discharge trend. The second gain coefficient is used to calculate the current request correction value to perform an upward adjustment correction. The expression for the first gain coefficient is: ； In the formula, The first gain coefficient; The basic gain coefficient; This refers to the temperature sensitivity coefficient. For reference temperature; This represents the lowest individual cell temperature in the battery pack. The expression for the second gain coefficient is: ； In the formula, This is the second gain coefficient; The basic gain coefficient; and .

5. The battery current zero-point control method in pure heating mode according to claim 1, characterized in that: In step S3, the requested current command sent to the charging device is updated in conjunction with the feedforward compensation mechanism. The expression for the feedforward compensation mechanism is: ； In the formula, This is a request for current sent to the charging device; This is the cumulative amount of the requested correction value for the current. The feedforward compensation component is obtained by summing the real-time power demand of the heating components and the real-time current consumption of the vehicle accessories.

6. The battery current zero-point control method in pure heating mode according to claim 1, characterized in that: Step S1 involves dynamically adjusting the preset zero-point target range based on battery temperature, including the following steps: pre-storing a temperature-current mapping table in the memory of the battery management system. The temperature-current mapping table defines multiple temperature ranges and the allowable charging current boundary value corresponding to each temperature range. In the temperature-current mapping table, as the temperature value of the temperature range increases, the absolute value of the allowable charging current boundary value corresponding to the temperature increases in a stepwise manner. The lowest cell temperature of the battery pack is monitored in real time. The allowable charging current boundary value corresponding to the lowest cell temperature is found in the temperature-current mapping table. The found allowable charging current boundary value is set as the lower limit of the preset zero-position target range within the current control cycle.

7. The battery current zero-point control method in pure heating mode according to claim 1, characterized in that: Before sending the request current command to the charging device in step S3, a trend prediction and correction step is also included: Step a: Establish the state vector of the current state model ,in This is the measured value of the terminal current. The rate of change of current; Step b: In each control cycle, perform the Kalman filter prediction and update steps to obtain the optimal estimate of the current change rate. ; Step c: When the direction of the current change rate points to the zero target range, and the absolute value of the current change rate exceeds the preset trend threshold, initiate trend prediction correction: Calculate the predicted convergence time : ； In the formula, This is the measured value of the terminal current; The center value of the zero-position target interval; like The output of the current request correction value will be temporarily suspended for a period of time: ； In the formula, This is the convergence time threshold; Maximum suspension time; Step d: During the suspension period, continuously monitor the current change. If the current change trend reverses or the current exceeds the safety boundary, immediately restore the correction value output.

8. The battery current zero-point control method in pure heating mode according to claim 4, characterized in that: The method also includes an abnormal circuit breaker protection mechanism, comprising the following steps: Step A: Define the three-level protection thresholds and corresponding fault counters: (1) Level 1 warning: If First protection threshold, set first fault count threshold, increase first gain coefficient. Generate early warning logs; (2) Level 2 alarm: If The second protection threshold sets a second fault count threshold, limiting the increment of the requested current. If the value is ≤0, an alarm signal is generated; (3) Level 3 circuit breaker: If Set the third protection threshold, set the third fault count threshold, send a stop command, disconnect the main relay, and record the fault code; Step B: Set the update rules for the fault counter: Current measurement value at the detection terminal in each control cycle ,like If the current is less than the corresponding level's current threshold, increment the corresponding level's fault counter by 1; if If the current threshold is greater than or equal to the corresponding level, then the fault counter for the corresponding level... Employ a decay-to-zero strategy: ； Step C: Each level of protection is independent of the others; when a higher-level protection is triggered, it automatically overrides the lower-level protection measures. Step D: After the Level 3 fuse is triggered, the system enters a fault-locked state, which can be restored by manual reset or by powering down and restarting the vehicle. Step E: Record the timestamp, current value, and temperature value of each protection trigger for subsequent fault analysis.

9. A battery current zero-point control system in pure heating mode, implemented based on the battery current zero-point control method in pure heating mode as described in any one of claims 1-8, characterized in that, The system includes: a data acquisition module, a zero-point deviation calculation module, a dynamic response factor calculation module, a current request correction calculation module, an instruction update and sending module, and a control logic management module; The data acquisition module: collects the terminal current measurement value of the battery pack and the actual output current value of the charging equipment in real time; The zero-position deviation calculation module calculates the current deviation based on the measured terminal current value of the battery pack and the preset zero-position target range. The dynamic response factor calculation module calculates the dynamic response factor of the charging device in real time based on the ratio of the current request adjustment amount to the actual output current change of the charging device within the historical control cycle. The current request correction calculation module calculates the current request correction value for the current control cycle based on the current deviation and the dynamic response factor. The instruction update and sending module updates the request current instruction sent to the charging device based on the calculated current request correction value. The control logic management module manages the control logic of the entire pure heating mode, including determining the entry and exit times of the pure heating mode and coordinating the execution order of the above modules.

10. A battery current zero-point control system in pure heating mode according to claim 9, characterized in that: The system also includes a status monitoring and safety protection module, which monitors the system's operating status in real time. If the system status is abnormal, it will exit zero-position control and issue an alarm.

Images