A dynamic control method and system for fast charging current of new energy vehicle

Abstract

The application discloses a new energy automobile fast charging current dynamic control method and system, the method comprises the following steps: collecting the battery voltage in real time, dividing the charging process into multiple charging stages according to the real-time battery voltage, assigning a corresponding current control strategy to each charging stage, and controlling the charging current according to the corresponding charging current control strategy of the current charging stage during charging. The application maximizes the charging power within the safety boundary and shortens the charging time by fusing the battery characteristic parameters in real time and constructing an adaptive charging request current decision model.

Description

Technical Field

[0001] This invention relates to the field of charging control, and in particular to a dynamic control method and system for fast charging current of new energy vehicles. Background Technology

[0002] Fast charging technology for new energy vehicles is a core direction for alleviating users' range anxiety and improving charging efficiency. Existing charging strategies cannot fully utilize the charging performance of supercharging stations and supercharging batteries. Current fast charging strategies employ constant current segmented mode or constant current and constant voltage charging mode, and obtain the required current through table lookup. Once a large current charging demand is met, the charging state may directly enter the end-of-charge current reduction process, resulting in longer charging time. This charging strategy is difficult to dynamically adapt to the real-time state of the battery, thus limiting charging efficiency. Although some solutions optimize the charging curve through temperature compensation or multi-segment current distribution, they still cannot maximize the charging performance of the power battery, resulting in charging time redundancy and wasted battery performance. Especially for vehicles supporting high-current supercharging, existing charging strategies cannot fully utilize the supercharging performance of the battery. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dynamic control method and system for fast charging current of new energy vehicles. By integrating battery characteristic parameters in real time, an adaptive charging request current decision model is constructed to maximize charging power and shorten charging time within the safety boundary.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A dynamic control method for fast charging current of new energy vehicles includes real-time acquisition of battery voltage, dividing the charging process into multiple charging stages based on the real-time battery voltage, assigning a corresponding current control strategy to each charging stage, and controlling the charging current according to the corresponding charging current control strategy obtained during charging based on the current charging stage.

[0006] During the charging process, the current battery temperature data is acquired in real time. Based on the current temperature data, the maximum charging current Imax and the minimum charging current Imin under the current state are obtained. The charging current of each charging stage is between the maximum charging current Imax and the minimum charging current Imin.

[0007] During the charging process, the maximum allowable charging current Imax and minimum allowable charging current Imin under the current temperature conditions are obtained by querying the charging matrix table in real time. Based on the two-dimensional charging matrix table composed of the remaining power battery capacity and power battery temperature, the BMS obtains the maximum allowable charging current Imax and minimum allowable charging current Imin under the current state by querying the real-time battery capacity and battery temperature.

[0008] The divided charging phases include a current increasing phase, during which the charging current increases linearly and the charging current is between the maximum allowable charging current Imax and the minimum charging current Imin.

[0009] The divided charging phases also include a constant current phase, during which charging is carried out while maintaining the requested charging current unchanged.

[0010] The divided charging phases also include a current decreasing phase, during which the charging current decreases linearly and the charging current is between the maximum allowable charging current Imax and the minimum charging current Imin.

[0011] Multiple voltage thresholds are preset, and the collected real-time maximum cell voltage Vmax is compared with the voltage thresholds. The current charging phase is judged according to the comparison result.

[0012] Voltage thresholds V1 and V2 are preset, where V1 > V2. The collected real-time maximum cell voltage Vmax is compared with the voltage thresholds V1 and V2 respectively. When it is judged that the condition Vmax < V1 is false, charging is stopped to prevent overcharging of the cell; when it is judged that the condition Vmax < V1 is true, then it is judged whether the condition Vmax < V2 holds. If it does not hold, the BMS requests the charging current from the charging pile according to Imin; if it is judged that the condition Vmax < V2 holds, then it enters the current increasing phase, and the BMS gradually increases the magnitude of the requested current I at a preset rate, and the requested I does not exceed the current maximum allowable charging current Imax during the charging process.

[0013] Voltage thresholds V3, V4, and V5 are preset, where V1 > V3 > V2 and V1 > V4 > V5;

[0014] During the current increasing phase, it is judged in real time whether the condition that the highest cell voltage Vmax of the current power battery system is ≥ V3 holds. If the condition does not hold, the requested current I is continued to be increased at a preset rate; if the condition Vmax ≥ V3 holds, then it enters the constant current phase.

[0015] During the charging process of the constant current phase, the charging requested current I is maintained unchanged and charging continues; during the charging process, it is judged in real time whether the condition that the highest cell voltage Vmax of the current power battery system is ≥ V4 holds. If the condition does not hold, the charging requested current I is maintained unchanged and charging continues; if the condition Vmax ≥ V4 holds, then it enters the current decreasing phase;

[0016] During the charging process in the current reduction phase, the requested current I is gradually reduced at a preset rate. During the charging process in the current reduction phase, it is determined in real time whether the condition of the highest cell voltage Vmax≥V1 of the current power battery system is met. If the condition is met, charging is stopped and the battery SOC value is set to 100%, and charging ends. If the condition of Vmax≥V1 is not met, and Vmax<V5 for 5 seconds, the charging phase jumps to the current increase phase. Otherwise, charging in the charging phase 3 continues until the condition of Vmax≥V1 is triggered, the vehicle power battery is fully charged and charging ends.

[0017] A dynamic control system for fast charging current of new energy vehicles includes: a data acquisition unit and a charging control unit; wherein the data acquisition unit acquires battery voltage in real time and sends it to the charging control unit, the charging control unit divides the charging process into multiple charging stages according to the real-time battery voltage, assigns a corresponding current control strategy to each charging stage, and controls the charging current according to the corresponding charging current control strategy obtained according to the current charging stage.

[0018] The advantages of this invention are: by fusing battery characteristic parameters in real time, an adaptive charging request current decision model and algorithm are constructed. Its advantages are:

[0019] 1. Adaptive charging strategy

[0020] By integrating battery characteristic parameters (such as maximum cell voltage and temperature) in real time, an adaptive decision-making model is constructed, breaking the traditional fixed segmented current mode and dynamically adjusting the requested current, which significantly improves charging efficiency and battery performance utilization.

[0021] 2. Multi-stage voltage threshold coordinated control

[0022] Five cell voltage thresholds (V1-V5) are set, and the current is dynamically adjusted in three stages: stage 1 rapidly increases the current, stage 2 stabilizes charging, and stage 3 intelligently reduces the current, maximizing the charging power within the safety boundary.

[0023] 3. Unleash the full potential of supercharging performance

[0024] Adopting an adaptive current adjustment strategy (increasing the charging request current by 10% Imax / second in stage 1 and decreasing the charging request current by 15% Imax / second in stage 3), it breaks through the power bottleneck of traditional multi-stage charging, especially suitable for high-current supercharging models, and improves the battery supercharging performance utilization rate by more than 30%.

[0025] 4. System compatibility and intelligence

[0026] Through the real-time interaction architecture between BMS and fast charging piles, it is compatible with existing charging facilities, can upgrade strategies without hardware modifications, and has low algorithm complexity (only voltage threshold comparison and current slope control are required), making it easy to scale up applications. Attached Figure Description

[0027] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0028] Figure 1 This is a flowchart of the dynamic control strategy for charging current of the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0030] This solution relates to the field of electrical system technology for new energy vehicles, specifically a dynamic adjustment strategy for fast charging current in new energy vehicles. It aims to maximize the charging performance of the power battery, shorten fast charging time, improve charging efficiency, and optimize user experience. Traditional battery charging typically employs three modes: constant current, constant voltage, and trickle charging. However, these modes have a fixed charging current, making dynamic adjustment impossible and failing to overcome the power bottleneck of traditional multi-stage charging. This solution addresses the problems of existing technologies by dynamically requesting charging current to control the charging process. This enables adaptation to high-current supercharging vehicles, improving battery supercharging performance utilization by over 30%. The solution dynamically adjusts the current in three stages: Stage 1 rapidly increases the current, Stage 2 stabilizes charging, and Stage 3 intelligently reduces the current, maximizing charging power within safe boundaries.

[0031] This embodiment of a dynamic control method for fast charging current of a new energy vehicle includes real-time acquisition of battery voltage, dividing the charging process into multiple charging stages based on the real-time battery voltage, assigning a corresponding current control strategy to each charging stage, and controlling the charging current according to the corresponding charging current control strategy obtained during charging based on the current charging stage. During charging, the system acquires battery voltage at a high frequency in real time and compares the voltage value with preset threshold values ​​for each interval to instantly determine which interval the battery is currently in, i.e., which charging stage it is currently in. Each charging stage is bound to an independent current control strategy. When it is determined that the corresponding stage has been entered, the charging current is requested and controlled according to the preset control logic of that stage. This embodiment is divided into three stages: Stage 1, Stage 2, and Stage 3. Stage 1 employs a current-increasing strategy, Stage 2 employs a constant current strategy, and Stage 3 employs a current-decreasing strategy. This approach can significantly improve charging speed. Within the battery's acceptable charging window, the current is gradually increased to a maximum value and then maintained at a high current for rapid charging. Once the battery is nearly fully charged, the current value is gradually decreased until it is fully charged, thereby shortening the charging time. Furthermore, this solution can effectively extend battery life because the current gradually increases or decreases between its maximum and minimum values, avoiding the impact of directly high or low current surges.

[0032] In this embodiment, the current battery temperature data is acquired in real time during charging. Based on the current temperature data, the maximum allowable charging current Imax and the minimum allowable charging current Imin under the current state are obtained. The charging current in each charging stage is between the maximum charging current Imax and the minimum charging current Imin. During charging, the maximum allowable charging current Imax and the minimum allowable charging current Imin under the current temperature conditions are obtained by querying the charging matrix table in real time. Based on the two-dimensional charging matrix table composed of the remaining power battery capacity and the power battery temperature, the BMS obtains the maximum allowable charging current Imax and the minimum allowable charging current Imin under the current state by querying the real-time battery capacity and battery temperature. The maximum allowable charging current Imax is the upper limit determined by the current temperature and the remaining power capacity to prevent battery overheating, separator shrinkage, or electrolyte decomposition. For example, above 45°C, Imax will be drastically reduced, or even limited to trickle charging. The minimum allowable charging current Imin is the lower limit determined by the current temperature and voltage, mainly set for low-temperature scenarios. For example, below 0°C, Imin may be set to a very small preheating current or strictly current-limited to prevent lithium plating on the negative electrode; at room temperature, Imin can be set to zero. During charging control, the maximum and minimum current values ​​under the current state can be obtained, and the requested charging current under real-time control can be limited between the maximum and minimum values ​​to ensure safety. This strategy, by incorporating temperature into the setting of maximum and minimum values, allows for real-time reduction of Imax when high-current fast charging causes the temperature to spike and approach the limit. This automatically suppresses the heat generation rate, forming a negative feedback loop of "overheating-current reduction-temperature reduction," significantly reducing the risk of thermal runaway and alleviating the pressure on the BMS cooling system, thereby limiting the charging current. At low temperatures, the coordinated limitation of Imin and Imax eliminates the current conditions for lithium dendrite formation, allowing for charging and self-heating with a very small safe current during the preheating stage. As the battery temperature recovers, Imax is gradually increased, seamlessly transitioning to normal fast charging, thus solving the pain point of being unable to fast charge at low temperatures.

[0033] The charging phases are divided into a current increase phase, referred to as phase 1. During the current increase phase, the charging current increases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

[0034] The divided charging phases also include a constant current phase, called Phase 2, in which the requested charging current is kept constant during charging.

[0035] The divided charging phases also include a current reduction phase, called phase 3. During the current reduction phase, the charging current decreases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

[0036] By dividing the charging current into three consecutive stages and constraining it throughout the process between the maximum allowable charging current Imax and the minimum allowable charging current Imin, a balance is achieved between fast charging and battery safety protection. The maximum charging current Imax and the minimum charging current Imin are limited by parameters such as temperature and remaining battery capacity, and their values ​​change dynamically, thus enabling dynamic adjustment and variation of the current. The first stage is the current increase stage. At the start of charging, the current begins from the set minimum allowable value Imin and increases linearly at a preset slope. This slow-start method avoids the impact of sudden current changes on the battery, effectively suppressing stress accumulation and potential side reactions in the electrode materials. Throughout the increase, the current value remains between Imin and Imax, ensuring continuous charging while preventing instantaneous exceedance of the battery's tolerance limits. This stage ends when the current reaches the constant current value requested by the system, or when the battery terminal voltage reaches the specified transition threshold, smoothly transitioning to the next stage. The second stage is the constant current stage. During this stage, the charging device maintains a constant value according to the requested value, continuously delivering energy to the battery with a stable high current; this is the core period for rapid energy replenishment. During the constant current phase, the battery terminal voltage gradually increases, while the current intensity strictly adheres to the limit of Imax to control temperature rise and polarization effects. Simultaneously, the current remains above Imin to prevent premature termination of the charging process due to low current. The duration of this phase depends on the battery's current state of charge and voltage feedback. The third phase is the current reduction phase. When the battery voltage approaches the charging limit voltage, or the state of charge is about to reach the target value, the system switches to this phase. The charging current starts from a constant value and gradually decreases along a predetermined linear ramp. The linear decrease in current is similar to the natural decay of current in traditional constant voltage charging, but its rate of decrease can be precisely controlled, thus more smoothly alleviating internal battery polarization. During this phase, the current remains within the safe window of Imin and Imax, allowing the battery to absorb energy more fully and reducing overpotential and heating side reactions. The charging process terminates when the current decreases to Imin and stabilizes, or when other cutoff criteria are met. The linear increase, constant maintenance, and linear decrease of current create a trapezoidal current waveform, effectively eliminating current jumps during phase transitions. By locking the charging current between Imax and Imin throughout the entire charging process, overcurrent surges and misjudgments of low current are eliminated from the control strategy level. While fully releasing the battery's fast charging potential, it effectively ensures cycle life and usage safety. It is suitable for optimized charging management of various secondary batteries such as lithium-ion batteries and lead-acid batteries.

[0037] In this embodiment, to divide the charging process into Stage 1, Stage 2, and Stage 3, multiple pre-set voltage thresholds are used. The real-time maximum cell voltage Vmax collected is compared with the voltage thresholds, and the current charging stage is determined according to the comparison results. Five cell voltage thresholds, V1, V2, V3, V4, and V5, are set respectively, where V1 > V3 > V2 and V1 > V4 > V5. If the condition Vmax < V1 is true, then it is further determined whether the condition Vmax < V2 holds. If it does not hold, the BMS requests the charging current from the charging pile according to Imin. If it is determined that the condition Vmax < V2 holds, then it enters Charging Stage 1; if the condition Vmax ≥ V3 holds, then it enters Charging Stage 2; if the condition Vmax ≥ V4 holds, then it enters Charging Stage 3. This solution compares five pre-set cell voltage thresholds (V1, V2, V3, V4, V5) with the highest single-cell voltage Vmax collected in real time by the battery management system, so as to accurately determine the charging stage and regulate the current, realizing stepped safe and fast charging. The threshold setting follows the constraints of V1 > V3 > V2 and V1 > V4 > V5. When charging starts, the BMS first determines whether Vmax < V1 holds, which is a global safety prerequisite; if it does not hold, charging is immediately stopped and an overvoltage fault is reported. After the condition is true, secondary discrimination is entered: if Vmax < V2 holds, it indicates that the current state of charge of the battery is relatively low and it can accept current ramping. The system determines to enter Stage 1: Current Increase Stage. At this time, the charging current starts from the minimum allowable value Imin and linearly increases at a fixed slope, remaining between Imin and Imax throughout the process, smoothly activating the electrochemical reaction and avoiding impact. As charging progresses, Vmax gradually rises. When Vmax ≥ V2 but has not reached V3, the condition Vmax < V2 is false. The system neither fully meets Stage 1 nor reaches the entry threshold of Stage 2. At this time, the BMS requests a constant small current of Imin from the charging pile according to the preset rule for charging. This constant-current transition interval can effectively buffer the polarization accumulation, create a stable electrochemical interface for subsequent high-current fast charging, and at the same time avoid mis-switching of stages due to instantaneous voltage fluctuations. When Vmax continues to rise to satisfy Vmax ≥ V3, the battery has entered a reliable range that can withstand large currents. The BMS determines to enter Stage 2: Constant Current Stage. At this time, the system requests and maintains a preset constant charging current (this value is within Imax) for efficient energy replenishment. The maximum cell voltage rises steadily, while the current remains rigidly constant until the voltage reaches the next threshold. When the BMS detects that the condition Vmax ≥ V4 holds, it indicates that the battery is about to enter the voltage limit area and immediately switches to Stage 3: Current Decrease Stage. The charging current then linearly decreases along the preset slope, and the rate of decrease is precisely controlled, so that the internal polarization of the battery gradually subsides, and at the same time the current is always limited between Imax and Imin. When the voltage approaches V5 and the current drops to near Imin, it is determined that charging is complete and charging is terminated.Throughout the process, Vmax is always clamped by V1, and all stage switching is hard-triggered by the voltage threshold. The logic is rigorous and unambiguous, which fundamentally ensures charging safety and lifespan.

[0038] Five cell voltage thresholds are set: V1, V2, V3, V4, and V5, where V1 > V3 > V2 and V1 > V4 > V5. V1 is the fully charged cell voltage, and V2 / V3 / V4 / V5 are cell voltage threshold parameters used to dynamically judge the maximum cell voltage Vmax during charging and adjust the charging request current in real time based on the judgment result. The V2 value is the maximum safe charging voltage threshold set based on the characteristics of the power battery cells, allowing for the highest possible charging rate; this value is slightly higher than V5 and slightly lower than V3. The V3 voltage threshold is the highest single-cell voltage threshold allowed to enter the stable charging phase; this value is slightly lower than V4. The V4 voltage threshold is the highest single-cell voltage threshold allowed to enter the intelligent current-reducing charging phase; this value is slightly lower than V5. The V5 voltage threshold is the lowest single-cell voltage threshold allowed to jump back to the stable charging phase.

[0039] V1 (Cell Full Charge Voltage): V1 is the highest safe voltage that the cell can reach, and it is also the absolute upper limit for charging termination. If Vmax ≥ V1 at any time, the BMS will immediately stop charging and report an overvoltage fault, ensuring safety at the hardware level. Therefore, V1 must be greater than all other thresholds.

[0040] V2 (Maximum Rate Charging Safe Voltage Threshold): V2 is the maximum safe charging voltage inflection point determined based on the cell material system. When Vmax is lower than V2, the cell polarization is small and can withstand current ramp-up, so the BMS enters stage 1 (current increase stage). If Vmax has exceeded V2 but not reached V3, it indicates that the cell needs buffering. The BMS actively requests the minimum current Imin for constant current transition to suppress polarization accumulation and create conditions for subsequent high-current fast charging. V2 is set slightly higher than the bounce threshold V5 and lower than V3, ensuring that the buffer zone is neither too wide nor that fast charging opportunities are lost.

[0041] V3 (Stable Charging Stage Entry Threshold): V3 is the voltage threshold that allows the battery cell to enter Stage 2 (Constant Current Stage) from the transition region. When Vmax ≥ V3, it indicates that the battery cell has the ability to withstand continuous high current and can be charged stably and efficiently. V3 is slightly lower than the current reduction threshold V4 to ensure that the constant current region has sufficient width.

[0042] V4 (Intelligent Current Reduction Stage Entry Threshold): V4 is the voltage point that triggers stage 3 (current reduction stage). When Vmax reaches V4, it indicates that the cell is approaching the voltage limit region, and the charging current must be linearly reduced to suppress side reactions and temperature rise. To prevent current fluctuations, V4 is set slightly higher than the bounce threshold V5, creating hysteresis.

[0043] V5 (Jump back to the lowest threshold of the stable charging stage): V5 is the decision point that allows returning to stage 1 for re - constant - current charging when Vmax drops below this value due to the decrease in current during the current - reduction process in stage 3. V5 is slightly lower than V4, forming a voltage hysteresis window to avoid frequent switching between stages near the critical voltage and ensure a smooth and stable charging process. When Vmax drops below V5, it can enter constant - current fast charging again until the voltage rises and then the current is reduced again, so as to fully saturate the battery cell, shorten the total charging time, and at the same time always clamp Vmax below V1.

[0044] In this embodiment: Voltage thresholds V1 and V2 are preset, where V1 > V2. The collected real - time maximum battery - cell voltage Vmax is compared with the voltage thresholds V1 and V2 respectively. When it is judged that the condition Vmax < V1 is false, charging is stopped to prevent overcharging of the battery cell; when it is judged that the condition Vmax < V1 is true, then it is judged whether the condition Vmax < V2 holds. If it does not hold, the BMS requests the charging current from the charging pile according to Imin; if it is judged that the condition Vmax < V2 holds, then it enters the current - increasing stage, and the BMS gradually increases the magnitude of the requested current I at a preset first rate, and during the charging process, the requested I does not exceed the current allowable maximum charging current Imax. The starting current of this stage is Imin, and the requested current is gradually increased at the first rate until the current reaches Imax; since Imax is associated with temperature, during the charging process, temperature changes will cause Imax to change. When Imax suddenly becomes smaller according to the temperature, if the real - time requested current is less than or equal to Imax at this time, then continue to increase the requested current at the first rate and limit the maximum current to Imax. If the requested current at this time is greater than Imax due to the change in Imax, then immediately adjust the real - time requested current to Imax.

[0045] Voltage thresholds V3, V4, and V5 are preset, where V1 > V3 > V2 and V1 > V4 > V5; during the current - increasing stage, it is judged in real - time whether the condition that the highest battery - cell voltage Vmax of the current power - battery system ≥ V3 holds. If the condition does not hold, then the requested current I is continued to be increased at a preset rate; if the condition Vmax ≥ V3 holds, then it enters the constant - current stage. During the charging process in the constant - current stage, the charging - requested current I remains unchanged and charging continues; during the charging process, it is judged in real - time whether the condition that the highest battery - cell voltage Vmax of the current power - battery system ≥ V4 holds. If the condition does not hold, then the charging - requested current I remains unchanged and charging continues; if the condition Vmax ≥ V4 holds, then it enters the current - decreasing stage;

[0046] During the charging process in the current reduction phase, the requested current I is gradually reduced according to the preset second rate. During the charging process in the current reduction phase, it is determined in real time whether the condition of the highest cell voltage Vmax≥V1 of the current power battery system is met. If the condition is met, charging is stopped and the battery SOC value is set to 100%, and charging ends. If the condition of Vmax≥V1 is not met, and Vmax<V5 for 5 seconds, the charging phase jumps to the current increase phase. Otherwise, charging in the charging phase 3 continues until the condition of Vmax≥V1 is triggered, the vehicle power battery is fully charged and charging ends.

[0047] The first and second rates are pre-calibrated rates. The first rate is temperature-dependent because the rate of current increase is correlated with the temperature rise. Under normal circumstances, the requested current is increased according to the default first rate, and the battery temperature change is monitored in real time during the current increase. If a sudden temperature change occurs, the first rate is reduced; otherwise, the first rate remains unchanged at the default rate. The reduction magnitude is positively correlated with the magnitude of the temperature change; a temperature change refers to a rate of temperature change exceeding a threshold. In the charging control strategy, the first and second rates are two pre-calibrated key ramp parameters, used for the current increase process in stage 1 and the current decrease process in stage 3, respectively. The first rate is not fixed but dynamically correlated with the battery temperature, stemming from the strong coupling between the current increase rate and the temperature rise. Under normal circumstances, the battery management system gradually increases the requested current according to the default first rate while monitoring the battery temperature change in real time. The system continuously calculates the temperature change rate and compares it with a preset threshold. When the temperature change rate does not exceed the threshold, i.e., no temperature change occurs, it indicates that the battery thermal state is stable and the current increase rate is within an acceptable range. In this case, the default first rate remains unchanged, and the charging process continues at the original ramp rate. Once the rate of temperature change exceeds the threshold, it is considered a temperature surge. This means that the heat accumulation caused by the current increase has exceeded the battery's normal heat dissipation capacity. Maintaining the original rate could lead to localized overheating, accelerated aging, or even safety risks. At this point, the BMS immediately triggers a rate adjustment mechanism, reducing the first rate. The reduction is not a fixed value but is positively correlated with the magnitude of the temperature surge. The more severe the surge, the higher the risk of thermal runaway, and the greater the reduction in the first rate, thus making the current rise more gradual and allowing the thermal management system time to respond. Conversely, if the surge magnitude is small, only a fine-tuning of the rate is needed to suppress the temperature rise. This closed-loop adjustment mechanism achieves adaptive thermal safety control during the current increase process without sacrificing charging efficiency. The second rate is used during the current reduction phase to ensure a smooth and controllable current reduction process. Together with the temperature-correlated design of the first rate, it forms a complete multi-stage charging current slope control system.

[0048] This embodiment also provides a dynamic control system for fast charging current of new energy vehicles, including: a data acquisition unit and a charging control unit; wherein the data acquisition unit collects battery voltage in real time and sends it to the charging control unit, and the charging control unit divides the charging process into multiple charging stages based on the real-time battery voltage, assigns a corresponding current control strategy to each charging stage, and controls the charging current according to the corresponding charging current control strategy obtained during charging based on the current charging stage. The acquisition unit can be a voltage, temperature, or other sensor, and the charging control unit is a battery management system (BMS).

[0049] The BMS (Battery Management System) is the core control unit, which controls the requested current during the charging process through strategies. These control strategies include:

[0050] During charging, the current battery temperature data is acquired in real time. Based on this data, the maximum allowable charging current (Imax) and minimum allowable charging current (Imin) under the current condition are determined. The charging current at each charging stage falls between these two values. During charging, the charging matrix table is queried in real time to obtain the maximum allowable charging current (Imax) and minimum allowable charging current (Imin) under the current temperature conditions. Based on a two-dimensional charging matrix table composed of the remaining battery capacity and battery temperature, the BMS obtains these values ​​by querying real-time battery capacity and temperature. The maximum allowable charging current (Imax) is an upper limit determined by the current temperature and remaining capacity, preventing battery overheating, separator shrinkage, or electrolyte decomposition. For example, above 45°C, Imax will drastically decrease, even limiting it to trickle charging. The minimum allowable charging current (Imin) is a lower limit determined by the current temperature and voltage, primarily set for low-temperature scenarios. For example, below 0°C, Imin may be set to a very small preheating current or strictly limited to prevent lithium plating on the negative electrode; at room temperature, Imin can be set to zero. During charging control, the maximum and minimum current values ​​under the current state can be obtained, and the requested charging current under real-time control can be limited between the maximum and minimum values ​​to ensure safety. This strategy, by incorporating temperature into the setting of maximum and minimum values, allows for real-time reduction of Imax when high-current fast charging causes the temperature to spike and approach the limit. This automatically suppresses the heat generation rate, forming a negative feedback loop of "overheating-current reduction-temperature reduction," significantly reducing the risk of thermal runaway and alleviating the pressure on the BMS cooling system, thereby limiting the charging current. At low temperatures, the coordinated limitation of Imin and Imax eliminates the current conditions for lithium dendrite formation, allowing for charging and self-heating with a very small safe current during the preheating stage. As the battery temperature recovers, Imax is gradually increased, seamlessly transitioning to normal fast charging, thus solving the pain point of being unable to fast charge at low temperatures.

[0051] The charging phases are divided into a current increase phase, referred to as phase 1. During the current increase phase, the charging current increases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

[0052] The divided charging phases also include a constant current phase, called Phase 2, in which the requested charging current is kept constant during charging.

[0053] The divided charging phases also include a current reduction phase, called phase 3. During the current reduction phase, the charging current decreases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

[0054] In this embodiment, to divide into stage 1, stage 2, and stage 3, multiple voltage thresholds are preset, and the collected real-time maximum cell voltage Vmax is compared with the voltage thresholds. According to the comparison results, the current charging stage is judged. Five cell voltage thresholds, V1, V2, V3, V4, and V5, are set respectively, where V1 > V3 > V2 and V1 > V4 > V5. If the condition Vmax < V1 is true, then it is further judged whether the condition Vmax < V2 holds. If it does not hold, the BMS requests the charging current from the charging pile according to Imin. If it is judged that the condition Vmax < V2 holds, then it enters charging stage 1; if the condition Vmax ≥ V3 holds, then it enters charging stage 2; if the condition Vmax ≥ V4 holds, then it enters charging stage 3. This scheme compares five preset cell voltage thresholds (V1, V2, V3, V4, V5) with the highest single-cell voltage Vmax collected by the battery management system in real time, so as to accurately determine the charging stage and regulate the current, realizing stepped safe and fast charging. The threshold setting follows the constraints of V1 > V3 > V2 and V1 > V4 > V5. When charging starts, the BMS first judges whether Vmax < V1 holds, which is the global safety premise; if it does not hold, charging is immediately stopped and an overvoltage fault is reported. After the condition is true, secondary discrimination is entered: if Vmax < V2 holds, it indicates that the current state of charge of the battery is relatively low and can accept current ramping. The system determines to enter stage 1: current increase stage. At this time, the charging current starts from the minimum allowable value Imin and linearly rises at a fixed slope, remaining between Imin and Imax throughout the process, smoothly activating the electrochemical reaction and avoiding impact. As charging progresses, Vmax gradually rises. When Vmax ≥ V2 but has not reached V3, the condition Vmax < V2 is false. The system neither fully meets stage 1 nor reaches the entry threshold of stage 2. At this time, the BMS requests a constant small current of Imin from the charging pile for charging according to the preset rule. This constant current transition interval can effectively buffer the polarization accumulation, create a stable electrochemical interface for subsequent high-current fast charging, and at the same time avoid mis-switching of stages due to instantaneous voltage fluctuations. When Vmax continues to rise to satisfy Vmax ≥ V3, the battery has entered a reliable range that can withstand large currents, and the BMS determines to enter stage 2: constant current stage. At this time, the system requests and maintains a preset constant charging current (this value is within Imax) for efficient energy supply. The maximum cell voltage rises steadily, while the current remains rigidly constant until the voltage reaches the next threshold. When the BMS detects that the condition Vmax ≥ V4 holds, it indicates that the battery is about to enter the voltage limit area, and immediately switches to stage 3: current decrease stage. The charging current then starts to linearly decrease along the preset slope, and the rate of decrease is precisely controlled, so that the internal polarization of the battery gradually subsides, and at the same time the current is always limited between Imax and Imin. When the voltage approaches V5 and the current drops to near Imin, it is judged that charging is completed and charging is terminated.Throughout the process, Vmax is always clamped by V1, and all stage switching is hard-triggered by the voltage threshold. The logic is rigorous and unambiguous, which fundamentally ensures charging safety and lifespan.

[0055] The data collection method and steps in this scheme include:

[0056] 1. During charging, the BMS system load of the new energy vehicle's power battery interacts with the fast charging pile to manage the charging process in real time, including requesting charging current, etc.

[0057] 2. During charging, the maximum allowable charging current Imax and minimum allowable charging current Imin under the current temperature conditions are obtained by querying the charging matrix table in real time. The charging matrix table is a two-dimensional matrix table provided by the power battery manufacturer, based on the remaining power battery capacity and power battery temperature. The BMS obtains the maximum allowable charging current Imax and minimum allowable charging current Imin under the current state by querying the real-time battery capacity and battery temperature.

[0058] 3. Five cell voltage thresholds are set: V1, V2, V3, V4, and V5, where V1 > V3 > V2 and V1 > V4 > V5. V1 is the fully charged voltage of the cell, and V2 / V3 / V4 / V5 are cell voltage threshold parameters used to dynamically judge the maximum cell voltage Vmax during charging and adjust the charging request current in real time based on the judgment result. The V2 value is the maximum safe charging voltage threshold set based on the characteristics of the power battery cell, which is slightly higher than V5 and slightly lower than V3. The V3 voltage threshold is the highest single cell voltage threshold allowed to enter the stable charging stage, which is slightly lower than V4. The V4 voltage threshold is the highest single cell voltage threshold allowed to enter the intelligent current reduction charging stage, which is slightly lower than V5. The V5 voltage threshold is the lowest single cell voltage threshold allowed to jump back to the stable charging stage.

[0059] 4. During charging, the voltage value Vmax of the highest-voltage cell in the current battery system is acquired in real time. This value is used for comparison with the cell voltage threshold. The charging current I is requested in real time during charging.

[0060] like Figure 1 As shown, the specific implementation method is as follows:

[0061] 1. After a new energy vehicle plugs into the fast charging gun and swipes its card, the vehicle control system (BMS) interacts with the fast charging station. Once the interaction enters the charging phase, the BMS adaptively adjusts the charging request current by integrating battery characteristic parameters in real time.

[0062] 2. After entering the charging process:

[0063] When the BMS determines that the condition Vmax < V1 is false, charging stops to prevent overcharging of the battery cells. When the BMS determines that the condition Vmax < V1 is true, it then checks whether the condition Vmax < V2 holds. If it does not hold, the BMS requests a charging current I from the charging pile at Imin. If it is determined that the condition Vmax < V2 holds, then it enters charging stage 1, and the BMS gradually increases the magnitude of the requested current I at a rate of (Imax * 10%) per second, and during the charging process, the requested I does not exceed the current maximum allowable charging current Imax. 10% is a calibratable parameter and is calibrated according to the actual charging parameters of new energy vehicles. During charging stage 1, the BMS continuously checks whether the condition that the highest cell voltage Vmax of the current power battery system ≥ V3 holds. If the condition does not hold, the BMS continues to increase the requested current I at a rate of (Imax * 10%) per second. If the condition Vmax ≥ V3 holds, then it enters charging stage 2.

[0064] During the charging process of charging stage 2, the BMS maintains the charging requested current I unchanged and continues charging. During the charging process, it continuously checks whether the condition that the highest cell voltage Vmax of the current power battery system ≥ V4 holds. If the condition does not hold, the BMS maintains the charging requested current I unchanged and continues charging. If the condition Vmax ≥ V4 holds, then it enters charging stage 3.

[0065] During the charging process of charging stage ③, the BMS gradually reduces the magnitude of the requested current I at a rate of (Imax * 15%) per second. During the charging process of charging stage 3, it continuously checks whether the condition that the highest cell voltage Vmax of the current power battery system ≥ V1 holds. If the condition holds, charging stops and the SOC is set to 100%, and charging ends. If the condition Vmax ≥ V1 does not hold, and Vmax < V5 and this persists for 5 seconds, then the charging stage jumps to charging stage 1. Otherwise, charging in charging stage 3 continues until the condition Vmax ≥ V1 holds, the vehicle's power battery is fully charged, and charging ends.

[0066] A dynamic adjustment strategy for the fast charging current of new energy vehicles in this solution constructs an adaptive charging requested current decision model and algorithm by fusing battery characteristic parameters in real time. Its advantages are as follows:

[0067] 1. Adaptive charging strategy

[0068] By fusing battery characteristic parameters (such as the highest cell voltage, temperature, etc.) in real time, an adaptive decision model is constructed, breaking the traditional fixed segmented current mode, dynamically adjusting the requested current, and significantly improving the charging efficiency and battery performance utilization rate.

[0069] 2. Multi-stage voltage threshold collaborative control

[0070] Five cell voltage thresholds (V1-V5) are set, and the current is dynamically adjusted in three stages: stage 1 rapidly increases the current, stage 2 stabilizes charging, and stage 3 intelligently reduces the current, maximizing the charging power within the safety boundary.

[0071] 3. Unleash the full potential of supercharging performance

[0072] Adopting an adaptive current adjustment strategy (increasing the charging request current by 10% Imax / second in stage 1 and decreasing the charging request current by 15% Imax / second in stage 3), it breaks through the power bottleneck of traditional multi-stage charging, especially suitable for high-current supercharging models, and improves the battery supercharging performance utilization rate by more than 30%.

[0073] 4. System compatibility and intelligence

[0074] Through the real-time interaction architecture between BMS and fast charging piles, it is compatible with existing charging facilities, can upgrade strategies without hardware modifications, and has low algorithm complexity (only voltage threshold comparison and current slope control are required), making it easy to scale up applications.

[0075] Obviously, the specific implementation of this invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A dynamic control method for fast charging current of new energy vehicles, characterized in that: This includes real-time acquisition of battery voltage, dividing the charging process into multiple charging stages based on the real-time battery voltage, assigning a corresponding current control strategy to each charging stage, and controlling the charging current based on the corresponding charging current control strategy obtained during charging according to the current charging stage.

2. The dynamic control method for fast charging current of new energy vehicles as described in claim 1, characterized in that: During the charging process, the current battery temperature data is acquired in real time. Based on the current temperature data, the maximum charging current Imax and the minimum charging current Imin under the current state are obtained. The charging current of each charging stage is between the maximum charging current Imax and the minimum charging current Imin.

3. The dynamic control method for fast charging current of new energy vehicles as described in claim 2, characterized in that: During the charging process, the maximum allowable charging current Imax and minimum allowable charging current Imin under the current temperature conditions are obtained by querying the charging matrix table in real time. Based on the two-dimensional charging matrix table composed of the remaining power battery capacity and power battery temperature, the BMS obtains the maximum allowable charging current Imax and minimum allowable charging current Imin under the current state by querying the real-time battery capacity and battery temperature.

4. A dynamic control method for fast charging current of new energy vehicles as described in any one of claims 1-3, characterized in that: The charging phases are divided into a current increase phase, during which the charging current increases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

5. The dynamic control method for fast charging current of new energy vehicles as described in claim 4, characterized in that: The divided charging phases also include a constant current phase, during which the requested charging current is kept constant.

6. The dynamic control method for fast charging current of new energy vehicles as described in claim 4, characterized in that: The divided charging phases also include a current reduction phase, during which the charging current decreases linearly and is between the maximum allowable charging current Imax and the minimum allowable charging current Imin.

7. The dynamic control method for fast charging current of new energy vehicles as described in claim 1, characterized in that: Multiple voltage thresholds are preset, and the real-time maximum cell voltage Vmax is compared with the voltage thresholds. The current charging stage is determined based on the comparison results.

8. The dynamic control method for fast charging current of a new energy vehicle as described in claim 7, characterized in that: Pre-set voltage thresholds V1 and V2, where V1 > V2. Compare the collected real-time maximum cell voltage Vmax with the voltage thresholds V1 and V2 respectively. When it is judged that the condition Vmax < V1 is false, stop charging to prevent overcharging of the cell; when it is judged that the condition Vmax < V1 is true, then judge whether the condition Vmax < V2 holds. If it does not hold, the BMS requests the charging current from the charging pile according to Imin; if it is judged that the condition Vmax < V2 holds, enter the current increase stage, and the BMS gradually increases the magnitude of the requested current I at a preset rate, and the requested I does not exceed the current maximum allowable charging current Imax during the charging process.

9. The dynamic control method for fast charging current of a new energy vehicle as described in claim 8, characterized in that: Pre-set voltage thresholds V3, V4, and V5, where V1 > V3 > V2, V1 > V4 > V5; During the current increase stage, continuously judge whether the condition that the highest cell voltage Vmax of the current power battery system is ≥ V3 holds. If the condition does not hold, continue to increase the requested current I at a preset rate; If the condition Vmax ≥ V3 holds, enter the constant current stage; During the charging process in the constant current stage, keep the charging requested current I unchanged and continue charging; during the charging process, continuously judge whether the condition that the highest cell voltage Vmax of the current power battery system is ≥ V4 holds. If the condition does not hold, keep the charging requested current I unchanged and continue charging; if the condition Vmax ≥ V4 holds, enter the current decrease stage; During the charging process in the current decrease stage, gradually reduce the magnitude of the requested current I at a preset rate; During the charging process in the current decrease stage, continuously judge whether the condition that the highest cell voltage Vmax of the current power battery system is ≥ V1 holds. If the condition holds, stop charging and set the battery SOC value to 100%, and the charging ends; If the condition Vmax ≥ V1 does not hold, and Vmax < V5 and lasts for 5 seconds, the charging stage jumps to the current increase stage; otherwise, still maintain the charging in stage 3 until the condition Vmax ≥ V1 holds is triggered, and the vehicle power battery is fully charged and the charging ends.

10. A dynamic control system for fast charging current of new energy vehicles, characterized in that: Including: Data acquisition unit, charging control unit; Among them, the data acquisition unit collects the battery voltage in real time and sends it to the charging control unit. The charging control unit divides the charging process into multiple charging stages according to the real-time battery voltage, assigns corresponding current control strategies to each charging stage, and obtains the corresponding charging current control strategy according to the current charging stage during charging to control the charging current.

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