Power limit protection control method and system for power battery of pure electric vehicle

Abstract

The invention relates to the technical field of batteries, and discloses a power limit protection control method and system for a power battery of a pure electric vehicle, and the method comprises the steps: S1, carrying out the real-time power integration with the continuous discharge capability of the battery as a boundary when the vehicle is discharged; s2, when the real-time power integral reaches the current maximum discharge capacity condition of the battery, reducing the power at a first rate to limit the discharge power; s3, when the power is limited to the current target discharge power, performing real-time condition judgment; s4, if the condition is met, amplifying the power to the current maximum discharge capacity of the battery at a second rate; the steps from S1 to S4 are carried out circularly. According to the method, judgment is carried out by utilizing the power integral and the maximum discharge capacity of the battery, and power limitation is carried out by combining the combined design of the first rate and the second rate, so that the starting time point of power limitation is more reasonable, the power switching process is gentle, and the maximum capacity of the battery can be fully exerted without exceeding the limit; the power performance and the energy utilization rate of the whole vehicle can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method and system for controlling power limiting protection of a power battery of a pure electric vehicle. Background Art

[0002] Power battery power limiting in pure electric vehicles (BEVs) involves proactively limiting the battery's maximum output (discharge) or input (charge) power under specific operating conditions or battery states to prevent risks such as overheating, overloading, and accelerated aging. This system aims to protect battery health by preventing temperature rise, electrolyte decomposition, and capacity degradation caused by high-power operation; improve safety by preventing extreme conditions such as thermal runaway and short circuits; extend battery life by reducing damage to electrode materials caused by high-current charging and discharging; and maintain a balance between vehicle power and range, effectively allocating energy. Therefore, power battery power limiting is a crucial strategy for ensuring battery safety, extending battery life, and optimizing vehicle performance.

[0003] Under complex working conditions such as low temperature and low SOC, full-load climbing or rapid acceleration, the battery's discharge power demand often rises sharply, easily exceeding its actual discharge capacity. The existing power limit protection control mechanism is not designed reasonably, exposing a series of problems: First, the power limit strategy of some systems is not sophisticated enough, and fails to accurately match the maximum available capacity of the battery in the current state, resulting in excessive discharge of the battery, which not only affects its service life, but may also cause after-sales disputes due to exceeding the usage limit in the warranty terms; second, during the power limit intervention process, the switching rate is too fast, resulting in a sharp rise and fall in output power, resulting in inconsistent torque output. Stability seriously affects driving smoothness and ride comfort, and even poses a safety hazard; in addition, the restrictions set by some systems are too stringent. Once the power limit logic is triggered, even if the battery status has returned to a safe range, the discharge capacity is difficult to recover in time, resulting in limited vehicle power performance, affecting normal driving and user experience; finally, the existing processing strategy is still insufficient in terms of energy utilization efficiency, lacks reasonable identification of battery capacity boundaries, and cannot maximize the battery potential while ensuring safety. As a result, the battery capacity cannot be fully explored and reasonably utilized, reducing the energy utilization rate and overall performance of the vehicle. Summary of the Invention

[0004] The present invention aims to provide a method and system for controlling power limiting protection of a power battery of a pure electric vehicle, so as to solve the technical problem that the existing power limiting protection control mechanism is not reasonably designed.

[0005] The basic solution provided by the present invention is: a power limiting protection control method for a pure electric vehicle power battery, comprising: S1: When the vehicle is discharging, real-time power integration is performed based on the battery's continuous discharge capacity; S2: When the real-time power integral reaches the current maximum discharge capacity of the battery, the power is reduced at a first rate to limit the discharge power; S3, when the power is limited to the current target discharge power, perform real-time condition judgment; S4: If the conditions are met, the power is amplified at a second rate to the current maximum discharge capacity of the battery.

[0006] S1-S4 are carried out in a cycle.

[0007] The present invention also provides a pure electric vehicle power battery power limit protection control system to implement a pure electric vehicle power battery power limit protection control method. The system includes: The battery management system is used to perform real-time power integration based on the battery's continuous discharge capacity when the vehicle is discharging; it is also used to obtain the current maximum discharge capacity of the battery; A power reduction module, configured to reduce power at a first rate to limit discharge power when the real-time power integral reaches the current maximum discharge capacity condition of the battery; A real-time condition judgment module is used to perform real-time condition judgment when the power is limited to the current target discharge power; The power recovery module is used to amplify the power to the current maximum discharge capacity of the battery at a second rate if the judgment condition in the real-time condition judgment module is met.

[0008] The working principle and advantages of the present invention are: Compared with the existing technology, it has the following advantages: 1) Using power integration combined with the battery's maximum discharge capacity (maximum allowable power) to determine power limit protection during discharge is more comprehensive and forward-looking than judging based solely on the current instantaneous discharge current. This method not only takes into account the impact of short-term high power, but also comprehensively evaluates the impact of energy accumulation over a period of time on the battery state. It is particularly advantageous in reflecting battery heat accumulation and preventing overheating and over-discharge risks. Through power integration, the battery management system can more accurately control energy output and dynamically adjust power limit strategies to improve efficiency while ensuring safety. At the same time, it can also effectively identify operating behaviors that frequently approach the power limit, avoiding battery damage caused by long-term accumulation, thereby extending battery life and improving system stability and reliability. It is a more scientific and practical power management method.

[0009] 2) By combining real-time power integration with the current battery's maximum discharge capacity, the timing of power limit triggering can be more reasonable, ensuring that power is appropriately limited and that the battery does not over-discharge. This not only effectively prevents permanent damage to the battery due to over-discharge, but also maximizes the battery's actual performance, ensuring a balance between the vehicle's power output and range. 3) During the power limiting process, a combination of the first rate and the second rate is adopted, which allows the power switching rate to decrease and increase slowly, achieving a smooth transition and imperceptible restriction, avoiding abrupt impacts on the driving experience, and improving the driving experience. Initially, the first rate is used to gradually reduce the power output to give the battery buffer time, reduce heat accumulation and imbalance between battery cells; then, according to the changes in the battery status, it switches to the second rate in a timely manner to ensure a rapid response to any potential risks and guarantee the safe operation of the battery. This dual-rate strategy not only effectively protects the battery from damage caused by over-discharge, but also maximizes the battery's efficiency and lifespan while ensuring driving safety, providing users with a more stable and reliable driving experience; in addition, this rate combination method also has good adaptability and scalability, and parameters can be adjusted according to different vehicle models, different batteries, and usage scenarios to meet personalized needs and the optimal match of the battery.

[0010] 4) Through real-time condition judgment, the system can dynamically adjust the power limit strategy based on the battery status while ensuring battery safety. This allows the limit to be quickly relaxed when conditions permit, allowing the discharge power to recover quickly. This not only avoids damage to the battery, but also ensures the continuity of vehicle power output and the stability of the driving experience, truly achieving a balance between safety and performance.

[0011] Through the above design, the power limit protection processing strategy of this solution is more perfect. It will not damage the battery when the battery capacity is fully utilized. It can give full play to the maximum capacity of the battery without exceeding its limit, which can improve the vehicle's power performance and energy utilization. At the same time, it can avoid battery overload damage, extend battery life, ensure safe and stable operation of the system, and achieve the optimal balance between performance and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A flow chart of a power limiting protection control method for a pure electric vehicle power battery provided by an embodiment of the present invention; Figure 2 This is a flow chart of a power limiting protection control system for a pure electric vehicle power battery provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The following is a further detailed description through specific implementation methods: Example 1 Basically as attached Figure 1 As shown: A power limiting protection control method for a pure electric vehicle power battery includes: S1: When the vehicle is discharging, real-time power integration is performed based on the battery's continuous discharge capacity; S2: When the real-time power integral reaches the current maximum discharge capacity of the battery, the power is reduced at a first rate to limit the discharge power; S3, when the power is limited to the current target discharge power, perform real-time condition judgment; S4: If the conditions are met, the power is amplified at a second rate to the current maximum discharge capacity of the battery.

[0014] S1-S4 are carried out in a cycle.

[0015] Specifically: The present invention focuses on the battery power limit protection control during discharge, and the charging power is executed according to the MAP without switching the meter.

[0016] In S1, the vehicle starts to discharge the high voltage, and the battery's allowable discharge power is the battery's maximum discharge capacity. Then the battery management system BMS performs real-time power integration calculation based on W=∫Pdt.

[0017] The battery management system (BMS) must continuously integrate discharge power to continuously update the real-time power integral. This ensures the stability and predictability of the control logic. Fixed time windows (such as 5 seconds, 10 seconds, or 30 minutes) are set, and a sliding window mechanism is used to determine in real time whether to reset the integral value (i.e., clear it and restart the calculation). Furthermore, power is filtered using methods such as exponentially weighted moving averages before integration to ensure a balanced balance between dynamic response and stability.

[0018] Compared to judging battery power protection control during discharge based solely on the current instantaneous discharge current, using power integration combined with the battery's maximum discharge capacity (maximum allowable power) is more comprehensive and forward-looking. This method not only considers the impact of short-term high power, but also comprehensively evaluates the impact of energy accumulation over a period of time on the battery state. It is particularly advantageous in reflecting battery heat accumulation and preventing overheating and over-discharge risks. Through power integration, the battery management system can more accurately control energy output and dynamically adjust power limiting strategies to improve efficiency while ensuring safety. At the same time, it can also effectively identify operations that frequently approach the power limit, avoiding battery damage caused by long-term accumulation, thereby extending battery life and improving system stability and reliability. It is a more scientific and practical power management method.

[0019] In S2, the process of determining the battery's maximum discharge capacity (peak discharge capacity) mainly involves the vehicle's battery management system (BMS) collecting real-time battery status data (such as temperature, SOC, SOH, etc.) and combining it with a predefined battery maximum discharge capacity table or model to calculate the maximum continuous discharge power X (battery allowable discharge power) that the battery can safely output under current conditions. This value X represents the current "battery maximum discharge capacity." The predefined maximum discharge capacity table is a set of tables or mappings developed based on battery characteristics and manufacturer-provided data. It is used to guide the maximum current or discharge power that the battery can safely output under different conditions (such as temperature, state of charge (SOC), etc.).

[0020] The condition for the real-time power integral to reach the maximum discharge capacity of the battery is that the real-time power integral is greater than the product of the current battery's allowable discharge power and a fixed time T (such as 10 seconds, 30 seconds, or 60 seconds), that is, when W = ∫Pdt > X*T, power limiting begins.

[0021] The first rate represents the rate of decrease, which can range from 3.5 to 5 kW / s, such as 3.5 kW / s and 5 kW / s. The first rate is adjusted based on the different battery capabilities of different projects. Battery capabilities include the discharge performance of battery cells. Cells with strong discharge performance correspond to a lower first rate than cells with weaker discharge performance. This means that different battery cells are used in different projects. Cells with strong discharge performance can have their rate of decrease appropriately slowed, while cells with weaker discharge performance can have their rate of decrease appropriately increased to protect the cells. Dynamic adjustment is not required under different operating conditions and is generally fixed to a specific, suitable value. This is done to reduce software complexity and, secondly, because power limiting is required to protect the battery when switching between meters. Inconsistent rates can cause different user experiences and lead to misunderstandings.

[0022] Battery cell discharge performance is determined by parameters provided by the battery cell supplier, including the cell internal resistance, cell type, and charge / discharge rate. A cell with low internal resistance, high discharge rate, slow temperature rise, low voltage drop, and slow capacity decay during high-current discharge is considered to have strong discharge performance. Similarly, a cell with high internal resistance, low discharge rate, rapid temperature rise, high voltage drop, and rapid capacity decay during high-current discharge is considered to have weak discharge performance.

[0023] During this process, once the system detects that the real-time power integral has reached the battery's maximum discharge capacity, it immediately switches to a different meter and takes action (discharging at the first rate and reducing power to implement power limiting). There's no need for a delay or waiting to confirm whether these changes are persistent and stable. This approach helps respond quickly to changes in battery status and avoid potential risks.

[0024] In S3, the target discharge power reflects the specific battery output requirements set by the user or control system, and is determined based on the actual application scenario and immediate needs. The target discharge power is the amount of power the vehicle or device expects to draw from the battery based on the current operating requirements. This may be to meet the driver's acceleration needs, maintain a constant speed, or other operational requirements. The target discharge power is adjustable and can be adjusted based on factors such as driver behavior (such as the degree of accelerator application) and the vehicle's operating mode (economy mode, sport mode, etc.).

[0025] The target discharge power is obtained by the BMS by checking the battery continuous discharge power table in real time based on the real-time battery status data such as SOC and temperature.

[0026] The real-time condition includes a preset time after the power is limited to the current target discharge power, and the preset time may be 5 seconds.

[0027] The real-time condition also includes that when the power is limited to the current target discharge power, the real-time power integral within a specified time does not exceed the continuous discharge capacity or is less than a preset proportion of the continuous discharge capacity, and the preset proportion is less than 1.

[0028] Real-time condition judgment is performed based on different projects and batteries. For example, 5 seconds after reaching the target discharge power, or when the real-time power integral is less than a certain value. Different battery cells are used in different projects. Cells with strong discharge performance can directly determine that the power integral does not exceed the continuous discharge capacity within the specified time, and then increase the power. Cells with weak discharge performance can tighten the conditions appropriately. When the power integral within the specified time is less than a preset proportion (<1) of the continuous discharge capacity, the power will be increased to protect the cell. Calibration is required to determine the continuous discharge capacity. The continuous discharge capacity is determined by the cell performance, and the cell supplier provides the continuous discharge MAP. The battery continuous discharge power is the battery continuous discharge capacity and is also the target discharge power.

[0029] In S4, the second rate represents the recovery rate, and the decrease rate is generally smaller than the recovery rate. The second rate can be 7.5 to 10kW / s, such as 7.5kW / s and 10kW / s. Similarly, the second rate is adjusted according to the different battery capabilities of different projects. The battery capability includes the discharge performance of the battery cell. The second rate corresponding to the battery cell with strong discharge performance is greater than the second rate corresponding to the battery cell with weak discharge capacity. That is, the battery cells used in different projects are inconsistent. The battery cells with strong discharge performance can appropriately increase the power recovery rate, and the battery cells with weak discharge performance can appropriately reduce the recovery rate to protect the battery cells. For the same reason as the first rate, the second rate does not need to be dynamically adjusted under different working conditions. The second rate is generally twice the first rate.

[0030] The battery management system is used to improve the vehicle's power performance and energy utilization when the vehicle is discharging, while avoiding overload damage, extending battery life, and ensuring the system's safe and stable power amplification at the second rate to the current battery's maximum discharge capacity.

[0031] The S1-S4 cycle is carried out to give full play to the maximum capacity of the battery without exceeding its limit, which can improve operation and achieve the optimal balance between performance and life.

[0032] like Figure 2 As shown, this embodiment also provides a pure electric vehicle power battery power limit protection control system, which executes a pure electric vehicle power battery power limit protection control method, including: Real-time power integration is performed based on the battery's continuous discharge capacity. It is also used to obtain the current maximum discharge capacity of the battery. A power reduction module, configured to reduce power at a first rate to limit discharge power when the real-time power integral reaches the current maximum discharge capacity condition of the battery; A real-time condition judgment module is used to perform real-time condition judgment when the power is limited to the current target discharge power; The power recovery module is used to amplify the power to the current maximum discharge capacity of the battery at a second rate if the judgment condition in the real-time condition judgment module is met.

[0033] It is understandable that the above system can fully execute the above method with the same effect, and will not be repeated here.

[0034] The present embodiment provides a method and system for controlling power limiting protection of a power battery of a pure electric vehicle. The power limiting protection processing strategy of this solution is more complete. The battery will not be damaged when the battery capacity is fully utilized. The battery's maximum capacity can be fully utilized without exceeding its limit. This can improve the power performance and energy utilization of the entire vehicle, while avoiding battery overload damage, extending battery life, ensuring safe and stable operation of the system, and achieving an optimal balance between performance and life.

[0035] Example 2 Different from the first embodiment, the first rate is calculated using the following formula:

[0036] in, represents the first rate; Respectively represent the maximum limit and minimum limit of the first rate; Taking 1 means the battery cell has strong discharge performance. A value of 0 indicates that the discharge performance of the battery cell is weak.

[0037] The second rate is calculated using the following formula:

[0038] in, represents the second rate; Respectively represent the maximum limit and minimum limit of the second rate; Taking 1 means the battery cell has strong discharge performance. A value of 0 indicates that the discharge performance of the battery cell is weak.

[0039] The power limiting protection control method and system for pure electric vehicle power batteries provided in this embodiment propose a strategy for dynamically adjusting the power regulation rate based on the discharge performance of the battery cell. This strategy evaluates the discharge capacity of the battery cell in real time and adaptively adjusts power reduction (first rate) and power recovery (second rate). This achieves differentiated control of battery cells in different health states, improves system robustness and user experience, and balances performance and life.

[0040] Example 3 The difference from the first and second embodiments is that the initial time window for power integral calculation is dynamically adjusted according to the battery status (such as temperature and internal resistance changes). In this embodiment, when the battery temperature is within an appropriate range (e.g., 25°C to 40°C), a longer time window is allowed to smooth power control and avoid frequent adjustments. When the temperature is too high or too low, it indicates that the battery is in a non-ideal operating state, and the time window needs to be shortened to achieve a faster response and prevent thermal runaway or low-temperature damage.

[0041] Use the following formula Dynamic Adjustment:

[0042] in, Indicates the maximum and minimum limits of the time window for power integral calculation; Indicates the influence coefficient of battery temperature on the time window.

[0043]

[0044] Wherein, T represents the current average battery temperature; Indicates the optimal temperature center of the battery, the middle temperature value between the maximum and minimum limits of the battery temperature, such as a maximum of 40°C and a minimum of 25°C. 30°C; Indicates the half-interval width, the difference between the maximum and minimum battery temperature limits. 15°C; It is the adjustment coefficient, which can be 1-2 to control the attenuation speed.

[0045] The function is a Gaussian decay function. The maximum value is 1, Maximum, at temperature deviation hour It decreases gradually, indicating that the more extreme the temperature, the faster the system needs to respond.

[0046] The power limit protection control method and system for a pure electric vehicle power battery provided in this embodiment utilizes the aforementioned strategy to dynamically adjust the time window for power integration calculation based on the actual operating status of the battery, thereby more accurately triggering the power recovery or reduction mechanism, protecting the battery while optimizing the vehicle's power performance. This approach contributes to a more intelligent and efficient battery management system. Furthermore, by introducing a temperature-based Gaussian decay function, continuous, smooth, and physically interpretable dynamic adjustment of the power integration time window is achieved, enabling faster system response when battery temperature is abnormal and more stable control when temperature is appropriate, thereby improving the adaptability and safety of power management.

[0047] The above is only an embodiment of the present invention. Common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. Ordinary technicians in the relevant field are aware of all common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the guidance of this application. Some typical well-known structures or well-known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A power limiting protection control method for a pure electric vehicle power battery, characterized in that: include: S1: When the vehicle is discharging, real-time power integration is performed based on the battery's continuous discharge capacity; S2: When the real-time power integral reaches the current maximum discharge capacity of the battery, the power is reduced at a first rate to limit the discharge power; S3, when the power is limited to the current target discharge power, perform real-time condition judgment; S4, if the conditions are met, amplifying the power at the second rate to the current maximum discharge capacity of the battery; S1-S4 are carried out in a cycle.

2. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S1, the battery management system performs continuous integration calculation based on the discharge power to continuously update the real-time power integral.

3. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S2, the battery management system collects the current battery status data in real time, and combines it with a predefined battery maximum discharge capacity table or model to calculate the current battery allowable discharge power that represents the current battery maximum amplification capacity; The condition for the real-time power integral to reach the current maximum discharge capacity of the battery is that the real-time power integral is greater than the product of the current battery allowable discharge power and the fixed time T.

4. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S2, the first rate is adjusted according to the battery capacity, where the battery capacity includes the discharge performance of the battery cells. The first rate corresponding to the battery cells with strong discharge performance is lower than the first rate corresponding to the battery cells with weak discharge performance.

5. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S3, the current battery status data is collected in real time through the battery management system, and the battery continuous discharge power table is checked in real time to calculate the current target discharge power.

6. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S3, the real-time condition includes that when the power is limited to the current target discharge power, the real-time power integral within a specified time does not exceed the continuous discharge capacity or is less than a preset ratio of the continuous discharge capacity, and the preset ratio is less than 1.

7. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 6, characterized in that: The real-time condition is determined according to the battery capacity; the battery capacity includes the discharge performance of the battery cell. The condition satisfied by the battery cell with strong discharge performance is that the real-time power integral does not exceed the continuous discharge capacity within a specified time. The condition satisfied by the battery cell with weak discharge performance is that the real-time power integral is less than a preset proportion of the continuous discharge capacity within a specified time.

8. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S3, the real-time condition includes a preset time after the power is limited to the current target discharge power.

9. The method for controlling power limiting protection of a power battery of a pure electric vehicle according to claim 1, characterized in that: In S4, the second rate is adjusted according to the battery capacity, where the battery capacity includes the discharge performance of the battery cells. The second rate corresponding to the battery cells with strong discharge performance is greater than the second rate corresponding to the battery cells with weak discharge performance.

10. A power limiting protection control system for a pure electric vehicle power battery, characterized in that: The method for controlling power limiting protection of a power battery of a pure electric vehicle according to any one of claims 1 to 9 is implemented; the system comprises: The battery management system is used to perform real-time power integration based on the battery's continuous discharge capacity when the vehicle is discharging; it is also used to obtain the current maximum discharge capacity of the battery; a power reduction module, configured to reduce power at a first rate to limit discharge power when the real-time power integral reaches the current maximum discharge capacity condition of the battery; A real-time condition judgment module is used to perform real-time condition judgment when the power is limited to the current target discharge power; The power recovery module is used to amplify the power to the current maximum discharge capacity of the battery at a second rate if the judgment condition in the real-time condition judgment module is met.

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