Electric vehicle power limiting method and system based on advanced power reduction strategy

Abstract

The invention provides an electric vehicle power limiting method and system based on an advanced power reduction strategy. The method comprises the following steps that the numerical value interval where the lowest battery cell voltage of a battery pack is located is judged in real time; if the lowest cell voltage is in the first interval, the power limiting operation is not executed; if the lowest cell voltage is in a second interval, executing a linear power reduction operation; if the lowest cell voltage is in a third interval, reducing the power to a first set value according to a set power reduction rate; if the lowest cell voltage is in a fourth interval, instantly reducing the power to a second set value; wherein the first interval, the second interval, the third interval and the fourth interval are continuous and full-range coverage intervals from large to small in sequence. The driving experience of a vehicle owner is improved, and irreversible damage caused by over-discharge of the battery is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicles, and in particular relates to a method and system for limiting electric vehicle power based on an advance power reduction strategy. Background Art

[0002] With the rapid development of electric vehicles, the importance of battery management system (BMS) in vehicle energy management is becoming increasingly prominent. When the vehicle is operating under low SOC (State of Charge) conditions, the minimum cell voltage may drop rapidly to the undervoltage threshold, causing the vehicle to fail to operate normally or even break down. In order to address this problem, a pre-undervoltage strategy is usually deployed in the prior art. When the minimum cell voltage is below a certain threshold, the output power of the vehicle is limited to protect the battery and vehicle performance.

[0003] In the prior art, the pre-undervoltage strategy usually adopts a linear power reduction method, which to some extent alleviates the driving frustration caused by the instantaneous power reduction. However, this strategy has the following shortcomings:

[0004] The existing pre-undervoltage strategy limits the vehicle power in stages based on three fixed voltage points. The power limit in each stage is a fixed value, and does not take into account the dynamic changes in power demand caused by the further decrease in the minimum voltage of the battery cell in the same stage. Therefore, when the battery cell voltage approaches the lower limit of the range, the power limit is insufficient, which may lead to the risk of over-discharge of the battery cell.

[0005] In the prior art, the severity of the power limit has not been adjusted dynamically as the minimum voltage of the battery cell decreases. For example, when the battery cell voltage is lower than 2600mV, the vehicle power limit is directly reduced to 30%, which is a large reduction compared to 70% in the first stage, and may have a greater negative impact on the driving experience. In fact, the lower the minimum voltage of the battery cell, the lower the output power of the vehicle should be to better protect the safety of the battery cell.

[0006] Although the existing technology partially alleviates the impact of power switching on driving smoothness by linear power reduction, when the power limit is adjusted by a large range (such as a sudden drop from 70% to 30%), it may still cause driving frustration and reduce the driving experience. Summary of the invention

[0007] The purpose of the present invention is to solve the deficiencies of the above-mentioned background technology and provide an electric vehicle power limiting method and system based on an early power reduction strategy to improve the driving experience of the owner and avoid irreversible damage caused by over-discharge of the battery.

[0008] The technical solution adopted by the present invention is: a method for limiting the power of an electric vehicle based on an early power reduction strategy, comprising the following steps:

[0009] Real-time determination of the numerical range of the minimum cell voltage of the battery pack;

[0010] If the lowest cell voltage is in the first interval, no power limiting operation is performed;

[0011] If the lowest cell voltage is in the second interval, a linear power reduction operation is performed;

[0012] If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate;

[0013] If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value;

[0014] Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

[0015] In the above technical solution, the process of performing the linear power reduction operation includes: making the vehicle power equal to the product of the multiplication factor and the original table lookup power corresponding to the current lowest battery cell voltage without restriction.

[0016] In the above technical solution, the rate factor is determined by an interpolation method based on the current lowest battery cell voltage and the maximum and minimum values ​​of the second interval.

[0017] In the above technical solution, the corresponding relationship between the rate factor K and the current lowest battery cell V is as follows:

[0018]

[0019] Among them, Max2 is the maximum value of the second interval, Min2 is the minimum value of the second interval, and A is a positive number.

[0020] In the above technical solution, the whole vehicle power includes the whole vehicle output power and the feedback power, and the whole vehicle output power and the feedback power are limited respectively according to the electric vehicle power limitation method based on the battery management system and the advance power reduction strategy.

[0021] In the above technical solution, the first set value is the product of the original table lookup power corresponding to the current lowest battery cell voltage without restriction and the first set ratio, and the set power reduction rate is used to ensure the smoothness of the driving experience.

[0022] In the above technical solution, the second set value is the product of the original table lookup power corresponding to the current lowest battery cell voltage that is not restricted and the second set ratio, so as to prevent the battery from being over-discharged.

[0023] In the above technical solution, the monitoring of the minimum cell voltage is performed in real time by the battery management system, and the power limit is adjusted in real time in response when a change in the minimum cell voltage is detected.

[0024] The present invention also provides an electric vehicle power limiting system based on an advance power reduction strategy, which is used to implement the electric vehicle power limiting method based on an advance power reduction strategy described in the above technical solution, including: a battery management system, a power limiting system;

[0025] The battery management system is used to determine in real time the numerical range of the minimum cell voltage of the battery pack;

[0026] The power limiting system is used to perform corresponding operations based on the value range of the minimum cell voltage:

[0027] If the lowest cell voltage is in the first interval, no power limiting operation is performed;

[0028] If the lowest cell voltage is in the second interval, a linear power reduction operation is performed;

[0029] If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate;

[0030] If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value;

[0031] Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

[0032] The present invention also provides a vehicle, comprising:

[0033] one or more processors;

[0034] A memory for storing one or more programs;

[0035] When the one or more programs are executed by the one or more processors, the one or more processors implement the electric vehicle power limitation method based on the early power reduction strategy as described in the above technical solution.

[0036] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the electric vehicle power limiting method based on the early power reduction strategy as described in the above technical solution is implemented.

[0037] The beneficial effects of the present invention are as follows: the present invention determines the interval to which the minimum cell voltage of the battery pack belongs in real time, and executes different power limitation strategies according to different intervals, including no limitation, linear power reduction, rapid power reduction at a set rate, and instantaneous power reduction. By determining the minimum cell voltage by interval, the full voltage range is covered, ensuring the safe operation of the battery system under different voltage conditions; in the high voltage interval (first interval), power limitation is not executed, the battery performance is fully utilized, and the power output efficiency of the whole vehicle is improved; in the medium and low voltage intervals, a gradual or rapid power reduction strategy is adopted, which can not only protect the battery and avoid over-discharge damage, but also meet the driving experience requirements of users and prevent driving discomfort caused by sudden power limitation; through a unified interval definition, the systematicness and consistency of the strategy are ensured.

[0038] Furthermore, in the second interval, the present invention calculates the vehicle power by multiplying the rate factor and the original table power in the linear power reduction process. The linear power reduction method avoids the abrupt switching of the power limit and ensures a smooth transition of the power. The rate factor is dynamically adjusted according to the change of the battery cell voltage, so that the power limit is more in line with the actual working state of the battery cell, which helps to extend the battery life. The vehicle power is adjusted with the rate factor as the core, and the algorithm is simple and efficient, which is convenient for the real-time implementation of the BMS system.

[0039] Furthermore, the calculation of the rate factor of the present invention is based on the current minimum cell voltage and the maximum and minimum values ​​of the second interval, and is determined by an interpolation method. The interpolation method is used to dynamically adjust the rate factor, thereby achieving a precise match between the cell voltage and the rate factor and improving the accuracy of power limitation. The interpolation calculation ensures the continuity of power adjustment and avoids power fluctuations caused by mutations, thereby further optimizing the driving experience. This method is easy to implement and reduces the complexity of the power limitation algorithm.

[0040] Furthermore, the present invention defines a linear relationship between the rate factor and the current minimum cell voltage, clarifies the mathematical relationship of the rate factor, and the formula processing facilitates system implementation and parameter optimization. Through the positive constraint of the proportional coefficient, the positive adjustment of the rate factor with voltage changes is ensured, reflecting the design intention that the lower the cell voltage, the greater the power limit. The formula description enhances the versatility of the method, and the formula parameters can be adjusted according to different battery characteristics to adapt to a variety of vehicle models and application scenarios.

[0041] Furthermore, the vehicle power of the present invention includes the vehicle output power and the feedback power, and both are limited respectively. The power output and energy feedback of the vehicle are taken into account to ensure the comprehensiveness and balance of power management. The feedback power limitation can prevent the overcharging of the battery cell caused by excessive regenerative braking feedback power when the battery voltage is low, thereby improving the safety of the system. The synchronous management of output power and feedback power further optimizes the energy flow of the vehicle and improves the overall efficiency of the battery management system.

[0042] Furthermore, the first set value of the present invention is the product of the original table lookup power corresponding to the current lowest battery cell voltage and the first set ratio, and the power reduction rate is designed to ensure driving stability. The first set value is calculated based on the original table lookup power and the ratio, ensuring that the power limit is gradually reduced on the basis of fully utilizing the battery performance, taking into account both power output and battery protection. The set power reduction rate smoothes the power adjustment process and prevents the negative impact of sudden power drops on the driving experience, such as vehicle jamming. Flexible power control is achieved in the medium voltage range, which improves the driving quality at low SOC (state of charge).

[0043] Furthermore, the second setting value of the present invention is the product of the original table lookup power corresponding to the current lowest cell voltage and the second setting ratio, which is intended to prevent the battery from being over-discharged. The second setting value ensures that the power is quickly and effectively limited under extremely low voltage conditions (such as the third interval or the fourth interval), fundamentally avoiding irreversible damage caused by over-discharge of the battery.

[0044] Emphasis is placed on the timeliness and effectiveness of power limitation, ensuring battery safety while minimizing the situation where the vehicle is under high voltage or completely loses power. Special treatment measures for low voltage ranges improve the pertinence and reliability of battery protection strategies.

[0045] Furthermore, the battery management system monitors the minimum cell voltage in real time and responds immediately when voltage changes are detected. The real-time monitoring and immediate response mechanism ensures that the power limit can quickly adapt to voltage changes, improving the dynamic adaptability of the system. Rapid adjustment of the power limit reduces the impact of voltage fluctuations on battery and vehicle performance, and improves the stability of the battery management system. The real-time design enhances the safety and user experience during vehicle operation, especially in complex working conditions.

[0046] In summary, the present invention avoids over-discharge and overload of the battery and prolongs the service life of the battery by limiting the power under low battery cell voltage conditions; reduces driving discomfort caused by power switching and improves user satisfaction through linear power reduction and smoothing processing; the strategy of rapid or instantaneous power reduction in the low voltage range effectively avoids irreversible damage to the battery and the system; and can be flexibly adjusted according to different vehicles and different battery characteristics, with a wide range of applications and strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The figure is a schematic diagram of a method flow of a specific embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not constitute a limitation on the present invention.

[0049] Example 1

[0050] like Figure 1 As shown, the present invention provides an electric vehicle power limiting method based on an advance power reduction strategy, comprising the following steps:

[0051] Real-time determination of the numerical range of the minimum cell voltage of the battery pack;

[0052] If the lowest cell voltage is in the first interval, no power limiting operation is performed;

[0053] If the lowest cell voltage is in the second interval, a linear power reduction operation is performed;

[0054] If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate;

[0055] If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value;

[0056] Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

[0057] Preferably, the values ​​of the first interval, the second interval, the third interval and the fourth interval are (2900V, +∞), [2700V, 2900V], [2500V, 2700V), (-

[0058] ∞,2500V).

[0059] Specifically, the process of performing a linear power reduction operation includes: making the vehicle power equal to the product of the multiplication factor and the original table lookup power corresponding to the current minimum battery cell voltage that is not restricted. The original table lookup power is obtained by querying the original table configured inside the electric vehicle program, and the table reflects the mapping relationship between the battery cell voltage and the power. The table is generated based on the battery performance test data and the parameters provided by the battery manufacturer, reflecting the optimal power output of the battery cell voltage under different conditions. Based on the current minimum battery cell voltage and other operating parameters (such as SOC, battery cell temperature, current, etc.), the original table is queried to obtain the original table lookup power corresponding to the current minimum battery cell voltage that is not restricted in real time.

[0060] The original table power is the theoretical power value under unrestricted conditions. By dynamically querying the original table power, it is possible to ensure that the calculation of the power limit is consistent with the current state of the battery cell (such as SOC, battery cell temperature, current, etc.), thereby providing a dynamic power reference value and laying the foundation for subsequent multiplier factor multiplication operations. The multiplier factor reflects the proportion of the power limit and is dynamically determined by the linear interpolation method based on the interval of the current minimum battery cell voltage.

[0061] Specifically, the rate factor is determined by interpolation method based on the current lowest cell voltage and the maximum value 2900V and the minimum value 2700V of the second interval. The corresponding relationship between the rate factor K and the current lowest cell V is as follows:

[0062]

[0063] Among them, Max2 is the maximum value of the second interval, Min2 is the minimum value of the second interval, and A is a positive number. As the minimum cell voltage V changes in real time, the multiplier factor K will be dynamically adjusted to ensure a smooth transition of the power limit.

[0064] In this embodiment, the relationship between the minimum cell voltage V and K of the whole pack is:

[0065]

[0066] Simplified:

[0067] K = 0.0015V-3.35.

[0068] The rate factor and power limit are dynamically adjusted as the minimum cell voltage changes, avoiding sudden changes in the power limit and improving driving comfort. The rate factor is flexibly defined through interpolation methods to meet the specific needs of different battery systems and voltage ranges. In the second voltage range, the power limit gradually decreases with the change of voltage, rather than a fixed stage limit, avoiding abrupt power changes. Linear interpolation makes the limit process smooth and significantly improves the driving experience.

[0069] The lower limit and interpolation range of the rate factor (such as 2700V to 2900V) can be adjusted according to different vehicle models and battery characteristics to enhance the flexibility of the strategy. The power limit is directly linked to the minimum cell voltage, effectively preventing over-discharge or over-charge of the cell and extending the battery life. Even in the power limit state, the system can still dynamically adjust the output power to provide minimum power support to prevent the vehicle from completely losing power.

[0070] When the vehicle is in a low state of charge (low SOC), the output power limit is dynamically adjusted through the rate factor to effectively extend the cruising range and prevent the vehicle from breaking down.

[0071] During long downhill driving or frequent braking, the regenerative power limit can use the same formula to calculate the rate factor, which can prevent overcharging or damage of the battery cells while ensuring energy recovery.

[0072] This solution is applicable to various types of electric vehicles, including urban passenger cars and long-distance commercial vehicles. By adjusting the upper and lower limits of the interpolation interval and the lower limit of the multiplier A, the requirements of different working conditions can be met.

[0073] Preferably, the original form should be established based on actual battery test data and regularly updated according to the battery attenuation status to ensure its dynamic validity. In addition to voltage, the original form can consider adding dimensions such as temperature and SOC to further improve the accuracy of power calculation.

[0074] Specifically, the vehicle power includes the vehicle output power and feedback power, and the vehicle output power and feedback power are limited according to the electric vehicle power limitation method based on the advance power reduction strategy of the battery management system. Both the output power and the feedback power are limited according to the interval of the minimum cell voltage (Vmin) monitored in real time by the battery management system (BMS). The limitations on output power and feedback power are intended to protect battery safety, prevent battery damage caused by over-discharge or over-charging, and ensure the stability of vehicle performance.

[0075] In the high voltage range, both the output power and the regenerated power are smoothly limited by linear interpolation to mitigate power fluctuations, improve the driving experience, and make full use of the high voltage performance of the battery.

[0076] In the medium voltage range, the output power and feedback power are reduced simultaneously, and the limitation range is increased, which extends the endurance under low SOC conditions and prevents the battery voltage from continuing to drop rapidly.

[0077] In the low voltage range, the output power and feedback power are limited by rapid decline or instantaneous power reduction to prevent the battery from over-discharge or damage, while ensuring the vehicle's minimum driving or braking functions as much as possible.

[0078] The output power and regenerative power use the same limiting logic and strategy, eliminating the need to design different algorithms for the two powers, simplifying the implementation complexity of the battery management system. The unified limiting strategy ensures the consistency of battery energy output and recovery, helping to optimize the energy efficiency of the entire vehicle. The synchronized limiting strategy avoids the mismatch between output power and regenerative power, and reduces the risk of conflict during power allocation. The consistent limiting strategy can protect the safety of the battery (such as preventing over-discharge or over-charging), while maintaining the stability and driving experience of the vehicle during power limiting.

[0079] Specifically, the first set value is the product of the original table lookup power corresponding to the current lowest battery cell voltage that is not restricted and the first set ratio, and the set power reduction rate is used to ensure a smooth driving experience.

[0080] Preferably, the power reduction rate is set to 4kW / S; the first setting ratio is 50%. The first setting value directly limits the output power of the vehicle, so that when the current minimum battery cell voltage is low but has not reached the critical threshold, the basic power output of the vehicle is maintained to protect the battery cell.

[0081] The power reduction rate is 4kW / s, which is used to adjust the speed of the vehicle's output power reduction. This rate slowly reduces the power output to prevent sudden power reduction from affecting the driving experience, such as vehicle setbacks and reduced driving comfort. By setting the power reduction rate and the first set ratio, it is ensured that the power limit protects the battery cells from damage due to over-discharge and maintains the stability and safety of the vehicle's driving.

[0082] When the lowest cell voltage enters a specific voltage range (eg, 2500mV-2700mV), power limiting is activated and the system calculates the first set value in real time.

[0083] The first set ratio is 50%, which means that the current power is limited to 50% of the original table power. The corresponding original table power is obtained by looking up the original table, and the target output power is calculated according to the first set ratio. The power limit gradually reduces the output power at a rate of 4kW / s until the first set value is reached.

[0084] The BMS system dynamically monitors the minimum cell voltage and adjusts the power limit strategy in real time when the voltage enters or leaves a specific range.

[0085] When the cell voltage returns to the high voltage range (such as >2700mV), the system gradually restores power output at the same rate (4kW / s).

[0086] The power limit is reduced by a gradual decrease (4kW / s) to reduce driving frustration and avoid vehicle power interruption caused by a significant instantaneous power reduction. The power reduction rate setting (4kW / s) ensures that the power changes gradually, avoiding abruptness and reduced comfort during driving.

[0087] Under low SOC conditions, the 50% power limit provides basic power output to meet the user's minimum driving needs (such as low-speed driving or parking). The first setting ratio (50%) is a balancing strategy that protects the battery while still ensuring that the vehicle can operate in a low-power state, reducing the user's anxiety about the vehicle being unable to drive due to voltage drop.

[0088] The power reduction and recovery strategy adjusted in real time by the present invention is adapted to the dynamic response requirements of the vehicle, thereby improving driving comfort and the real-time performance of the system.

[0089] When the battery cell voltage drops to a specific range (such as 2500mV-2700mV), the vehicle ensures low-power operation through the first set value and power reduction rate, effectively extending the cruising range and preventing the vehicle from breaking down.

[0090] Under frequent acceleration or braking conditions, the power limit is adjusted at a smooth decreasing rate, reducing the impact on the battery cells and extending battery life.

[0091] In high-power load conditions (such as climbing a steep slope or driving at full load), the power limit is dynamically adjusted to prevent over-discharge of the battery cells while ensuring that the vehicle has sufficient basic power output.

[0092] The first setting ratio of 50% is the preferred value and can be adjusted according to the actual application scenario. For example, when the battery cell temperature is low, the ratio can be appropriately increased (such as 60%) to reduce the impact of power limitation on power output. In the case of poor battery cell health state (SOH), the ratio can be appropriately reduced (such as 40%) to further strengthen battery cell protection.

[0093] 4kW / s is the preferred value set for general electric vehicles, which can be optimized and adjusted according to the vehicle model and driving requirements: for high-end vehicles or scenarios with higher requirements for driving stability, a lower drop rate (such as 2kW / s) can be set. For emergency protection needs (such as rapid voltage drop), the rate can be temporarily increased (such as 6kW / s) to quickly respond to protection.

[0094] The original table lookup power needs to be dynamically calculated in real time based on parameters such as the minimum cell voltage, SOC, cell temperature, etc. to ensure the accuracy of the power limit value.

[0095] The first set value (50%) maintains the vehicle's minimum power output while ensuring the safety of the battery cell to avoid complete loss of power. The power reduction rate (4kW / s) gradually limits the power to reduce driving frustration and improve the driving experience. This technical solution can dynamically respond to real-time changes in battery cell voltage, seamlessly adjust power limits, and adapt to different driving conditions and vehicle types. By setting the power reduction rate, the power limitation process is parameterized, which is convenient for deployment in electric vehicles.

[0096] Specifically, when the minimum cell voltage is in the fourth interval, the vehicle may damage the battery if it discharges further. The second set value is the product of the original table lookup power corresponding to the current minimum cell voltage without restrictions and the second set ratio to prevent over-discharge of the battery. The second set ratio is 20%.

[0097] Preferably, the minimum cell voltage is lower than 2500V, at which point the battery voltage level is close to or has reached the over-discharge threshold, and continued discharge may cause irreversible damage to the battery. When the minimum cell voltage is in the fourth interval, strict power limitation measures must be taken to avoid over-discharge of the cell. Over-discharge of the cell can cause irreversible damage to the active substances, such as electrolyte decomposition, lithium metal precipitation, etc., which seriously affects the battery life and even causes safety problems. By limiting the vehicle power to 20% of the original table power, ensure that the vehicle can continue to run, while reducing the discharge current of the cell to a minimum to prevent further voltage drop. Ensure that the vehicle still has a minimum power output under extreme conditions to meet the user's emergency driving needs.

[0098] The second setting value limits the vehicle power to 20% of the original table power, effectively reducing the discharge intensity of the battery cell and slowing down the rapid drop in voltage. By limiting the power output, the battery cell voltage is maintained within a safe range to avoid irreversible damage caused by the voltage continuing to drop to the over-discharge range.

[0099] Even at extremely low cell voltage (<2500V), the vehicle can still maintain a minimum power output to avoid the "breakdown" phenomenon caused by complete loss of power. Under the fourth interval power limit strategy, users can still drive at a low speed to the nearest charging station or safe area to meet emergency driving needs.

[0100] The second set value is calculated in real time based on the current minimum cell voltage to ensure that the power limit always matches the actual state of the cell. When the system detects that the minimum cell voltage enters the fourth interval, it can respond immediately and adjust the power output to maximize the protection of the cell safety.

[0101] Specifically, the monitoring of the minimum cell voltage is performed in real time by the battery management system, and the power limit is adjusted in real time in response when a change in the minimum cell voltage is detected.

[0102] Example 2

[0103] This embodiment aims at the minimum cell voltage V_min monitored in real time by the battery management system (BMS) at low SOC (state of charge), and protects battery safety through a dynamic power limiting strategy while taking into account the driving experience. Considering that the minimum cell voltage may rise again, the strategy process is improved, and a dynamic adjustment and smooth transition mechanism is added to ensure clear logic and efficient response. Specifically, the following steps are included:

[0104] Step 1: System Initialization

[0105] 1.1) BMS startup and self-test: The system is powered on to complete initialization and check the working status of each module (including voltage monitoring sensor, current acquisition unit, temperature sensor, etc.). After confirming that there is no fault, enter the monitoring mode.

[0106] 1.2) Enter high-voltage operation mode: Confirm that the vehicle is in high-voltage state, and start real-time monitoring of parameters such as minimum cell voltage V_min, SOC, cell temperature, etc.

[0107] Step 2: Real-time monitoring of the minimum cell voltage

[0108] 2.1) Data collection and update: Collect all cell voltage data multiple times per second and update the minimum cell voltage V_min.

[0109] 2.2) Interval judgment: According to the real-time value of V_min, determine its interval:

[0110] The first interval: (2900V, +∞)

[0111] Second interval: [2700V, 2900V]

[0112] The third range: [2500V, 2700V)

[0113] The fourth interval: (-∞, 2500V)

[0114] 2.3) Enter the corresponding interval strategy: execute the corresponding power limit strategy according to the interval.

[0115] Step 3: Power limit strategy for each interval

[0116] (1) First interval: (2900V, +∞)

[0117] Strategic goal: Unlimited power.

[0118] Specific implementation: The vehicle power maintains the original table power P0. Continuously monitor V_min, and if it drops below 2900V, switch to the second interval strategy.

[0119] (2) Second interval: [2700V, 2900V]

[0120] Strategic goal: Linearly reduce power and gradually reduce the power output of the entire vehicle.

[0121] Specific implementation:

[0122] 3.2.1) Calculation of the multiplication factor: Calculate the multiplication factor K based on V_min: K = 0.0015 × V_min - 3.35

[0123] 3.2.2) Calculation of limited power: P_limited = K × P0

[0124] 3.2.3) Dynamic power adjustment: The output power is gradually adjusted according to the above formula to ensure driving stability.

[0125] 3.2.4) Dynamic monitoring: If V_min<2700V, switch to the third interval strategy. Recovery processing: If V_min>2900V and lasts for more than 3 seconds, gradually restore power to P0: P_recovered=P_current+(P0-P_current)×t / T

[0126] The default recovery rate is 4kW / s.

[0127] t represents the current time point from the start of power adjustment, which is the same reference point as the starting point of T. T is the total time required for the power to be adjusted from the current limit value to the target limit value (3) The third interval: [2500V, 2700V)

[0128] Strategic goal: Rapidly reduce power to prevent the battery cell voltage from continuing to drop.

[0129] Specific implementation:

[0130] 3.3.1) Calculate the first setting value: P_first = 0.5 × P0

[0131] 3.3.2) Rapid power reduction: The power is limited to decrease at a rate of 4 kW / s until P_first is reached.

[0132] 3.3.3) Dynamic monitoring: If V_min<2500V, switch to the fourth interval strategy.

[0133] Recovery processing: If V_min>2700V and lasts for more than 3 seconds, switch to the second interval strategy: P_adjusted=P_first+(P_limited-P_first)×t / T dynamically adjust the power and smoothly switch to the second interval limit.

[0134] (4) The fourth interval: (-∞, 2500V)

[0135] Strategic goal: Strictly limit power to prevent over-discharge of battery cells.

[0136] Specific implementation:

[0137] 3.4.1) Calculate the second setting value: P_second=0.2×P0

[0138] 3.4.2) Instantaneous power adjustment: quickly limit the vehicle power to P_second.

[0139] 3.3.3) Monitor cell voltage changes: If V_min>2500V and lasts for more than 3 seconds, switch to the third interval strategy and gradually adjust the power to P_first.

[0140] Execute action:

[0141] Release the current strict restriction: release the current second setting value P_second=0.2×P0.

[0142] Switch to the third interval strategy: limit power adjustment to P_first = 0.5 × P0. Smooth transition power: P_adjusted = P_second + (P_first - P_second) × t / TT: The transition time is set to 1-2 seconds to ensure driving stability.

[0143] Dynamic monitoring:

[0144] If the voltage further rises to V_min>2700V, switch to the second interval strategy.

[0145] If the voltage drops rapidly below 2500V again, the strategy returns to the fourth interval immediately.

[0146] Example 3

[0147] The present invention also provides an electric vehicle power limiting system with an advance power reduction strategy, which is used to implement the electric vehicle power limiting method based on the advance power reduction strategy described in the above technical solution, including: a battery management system, a power limiting system;

[0148] The battery management system is used to determine in real time the numerical range of the minimum cell voltage of the battery pack;

[0149] The power limiting system is used to perform corresponding operations based on the value range of the minimum cell voltage:

[0150] If the lowest cell voltage is in the first interval, no power limiting operation is performed;

[0151] If the lowest cell voltage is in the second interval, a linear power reduction operation is performed;

[0152] If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate;

[0153] If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value;

[0154] Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

[0155] Example 4

[0156] The present invention also provides a vehicle, comprising:

[0157] one or more processors;

[0158] A memory for storing one or more programs;

[0159] When the one or more programs are executed by the one or more processors, the one or more processors implement the electric vehicle power limitation method based on the early power reduction strategy as described in the above technical solution.

[0160] Example 5

[0161] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the electric vehicle power limiting method based on the early power reduction strategy as described in the above technical solution is implemented.

[0162] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0163] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0164] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0165] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0166] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

[0167] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for limiting electric vehicle power based on an early power reduction strategy, characterized in that: The following steps are involved: Real-time determination of the numerical range of the minimum cell voltage of the battery pack; If the lowest cell voltage is in the first interval, no power limiting operation is performed; If the lowest cell voltage is in the second interval, a linear power reduction operation is performed; If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate; If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value; Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

2. A method according to claim 1, characterized in that: The process of performing the linear power reduction operation includes: making the vehicle power equal to the product of the multiplication factor and the original table lookup power corresponding to the current lowest battery cell voltage that is not restricted.

3. A method according to claim 2, characterized in that: The multiplication factor is determined by an interpolation method based on the current lowest cell voltage and the maximum and minimum values ​​of the second interval.

4. A method according to claim 2, characterized in that: The corresponding relationship between the rate factor K and the current lowest battery cell V is as follows: Among them, Max2 is the maximum value of the second interval, Min2 is the minimum value of the second interval, and A is a positive number.

5. A method according to claim 1, characterized in that: The whole vehicle power includes the whole vehicle output power and the feedback power, and the whole vehicle output power and the feedback power are limited respectively according to the electric vehicle power limitation method based on the battery management system and the advance power reduction strategy.

6. A method according to claim 1, characterized in that: The first set value is the product of the original table lookup power corresponding to the current lowest battery cell voltage that is not restricted and the first set ratio. The set power reduction rate is used to ensure a smooth driving experience.

7. A method according to claim 1, characterized in that: The second set value is the product of the original table lookup power corresponding to the current lowest battery cell voltage without restriction and the second set ratio, so as to prevent the battery from being over-discharged.

8. A method according to claim 1, characterized in that: The monitoring of the minimum cell voltage is performed in real time by the battery management system, and the power limit is adjusted in real time in response when a change in the minimum cell voltage is detected.

9. An electric vehicle power limiting system based on an early power reduction strategy, characterized in that: The method for limiting electric vehicle power based on the early power reduction strategy for implementing any one of claims 1 to 8 comprises: a battery management system and a power limiting system; The battery management system is used to determine in real time the numerical range of the minimum cell voltage of the battery pack; The power limiting system is used to perform corresponding operations based on the value range of the minimum cell voltage: If the lowest cell voltage is in the first interval, no power limiting operation is performed; If the lowest cell voltage is in the second interval, a linear power reduction operation is performed; If the lowest cell voltage is in the third interval, the power is reduced to the first set value according to the set power reduction rate; If the lowest cell voltage is in the fourth interval, the power is instantly reduced to the second set value; Among them, the first interval, the second interval, the third interval and the fourth interval are intervals that are continuous from large to small and cover the entire range.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the electric vehicle power limiting method based on the advance power reduction strategy as described in any one of claims 1 to 8 is implemented.

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