A method and system for battery balancing control of urban rail trains based on dynamic temperature compensation

Abstract

This invention relates to the field of power supply or distribution technology, and discloses a method and system for equalization control of urban rail train batteries based on dynamic temperature compensation. The method includes: collecting surface temperature samples of each battery cell within the battery pack, triggering a dynamic compensation mode according to the temperature change rate and a preset temperature change threshold, and outputting the temperature change rate under the dynamic compensation mode; performing heat conduction recursion and exponential weighted prediction based on the surface temperature samples, and outputting the predicted internal temperature of the battery cell; generating a feedforward compensation voltage based on the predicted internal temperature and temperature change rate; constructing a time-varying equalization voltage upper threshold based on the real-time voltage; and performing bypass equalization discharge and exit determination based on the comparison result between the real-time voltage and the corresponding upper threshold, outputting a dynamic compensation mode exit confirmation signal. This invention enables the equalization threshold to be dynamically corrected according to temperature trends and internal thermal states, alleviating the equalization lag caused by a fixed compensation coefficient under rapid temperature change conditions in urban rail transit.

Description

Technical Field

[0001] This invention relates to the field of power supply or distribution technology, and in particular to a method and system for equalization control of urban rail train batteries based on dynamic temperature compensation. Background Technology

[0002] Currently, urban rail trains frequently travel between tunnels and open-air platforms during operation, causing drastic temperature fluctuations in the battery compartment environment within minutes. To ensure the charging and discharging consistency of each cell in the series-connected battery pack, existing equalization management systems typically acquire the surface temperature of each cell at a fixed sampling period and compensate for the upper limit of the equalization charging voltage or the bypass discharge threshold based on a preset fixed temperature compensation coefficient. The equalization circuit then adjusts the bypass current accordingly. This processing path relies on real-time acquisition values ​​of surface temperature and empirical coefficients. While it can maintain basic voltage balance under conditions of relatively gentle temperature changes, its real-time response and accuracy become significantly insufficient when the temperature change rate of the battery compartment increases substantially.

[0003] For example, during the process of a train moving from a low-temperature tunnel to a high-temperature platform, the internal temperature may rise from 10°C to 45°C within 5 minutes. Due to its thermal inertia and a fixed sampling interval of 10 seconds, the temperature update speed of the individual cell surface temperature sensor lags far behind the actual temperature rise inside the cell. At the same time, the equalization algorithm continues to use the compensation coefficient set under low-speed temperature change scenarios, and cannot detect the rapid temperature rise trend, causing a delay in the timing of the equalization circuit's bypass discharge. High-temperature cells fail to discharge in time due to an overestimation of the upper limit of the charging voltage, while low-temperature cells over-discharge due to excessive compensation. The voltage difference between individual cells in the battery pack can quickly exceed 150mV within 10 minutes, triggering overcharge or undercharge protection, and even causing energy waste and thermal safety issues. Existing technology cannot meet the requirements of rapid response and high precision in equalization control under drastic temperature change conditions.

[0004] Therefore, there is an urgent need for a balancing control scheme that can detect the internal temperature development trend of battery cells and dynamically adjust the compensation voltage even under rapid temperature change rates exceeding 5℃ / min. By introducing temperature prediction and dynamic feedforward compensation mechanisms, the balancing judgment can adapt to the impact of drastic temperature changes on the charge state of individual cells in advance, and stabilize the voltage difference between cells within a safety margin of less than 50mV. This significantly improves the real-time balancing performance, cycle life, and operational reliability of the battery pack under complex tunnel conditions. Summary of the Invention

[0005] To address the aforementioned technical shortcomings, the present invention aims to propose a dynamic temperature compensation-based battery equalization control method for urban rail trains. This method addresses the technical problems in existing technologies where fixed compensation coefficients cannot adapt to rapid temperature changes, especially when the cabin temperature rises from 10°C to 45°C in 5 minutes with a fixed sampling interval of 10 seconds. This results in the inability to predict temperature trends and dynamically correct compensation voltage, leading to equalization lag, overcharging or undercharging, and voltage differences exceeding 150mV.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a method for equalization control of urban rail train batteries based on dynamic temperature compensation.

[0007] The method for equalizing the battery of urban rail trains based on dynamic temperature compensation includes: Step S10: Obtain the surface temperature sampling value of each battery cell in the urban rail train battery pack, and execute the dynamic compensation mode activation task based on the surface temperature sampling value using temperature change rate calculation and preset temperature change threshold triggering mechanism, and output the battery cell temperature change rate under dynamic compensation mode. Step S20: Based on the temperature change rate of the battery cell under the dynamic compensation mode and the corresponding surface temperature sampling value, the internal temperature prediction task is performed using a heat conduction recursion and exponential weighted prediction mechanism, and the predicted internal temperature of the battery cell is output. Step S30: Based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, the feedforward compensation voltage calculation task is performed by using a two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism, and the feedforward compensation voltage of each battery cell is output. Step S40: Obtain the real-time voltage of each battery cell. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, perform the time-varying equalization threshold construction task using the time-varying equalization threshold mapping mechanism, and output the time-varying equalization voltage upper threshold of each battery cell. Step S50: Based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, perform bypass equalization discharge control and dynamic compensation exit determination, and output a dynamic compensation mode exit confirmation signal. Preferably, step S10, which involves acquiring surface temperature sampling values ​​of each battery cell within the urban rail train's battery pack, performing dynamic compensation mode activation based on temperature change rate calculation and a preset temperature change threshold triggering mechanism using the surface temperature sampling values, and outputting the battery cell temperature change rate under dynamic compensation mode, specifically includes: Step S101: Collect surface temperature sampling values ​​of each battery cell at multiple sampling times according to a preset fixed sampling period, determine the order of the multiple sampling times as the sampling time sequence, and form a surface temperature sequence corresponding to each battery cell based on the sampling time sequence. Step S102: Calculate the difference between the surface temperature sampling values ​​of the same battery cell at adjacent sampling times, and convert them into the instantaneous temperature change rate according to the preset fixed sampling period; perform median filtering and first-order hysteresis filtering on multiple consecutive instantaneous temperature change rates in sequence to obtain the filtered temperature change rate. Step S103: Convert the filtered temperature change rate into a change per minute and acquire the train tunnel entry / exit indicator signal; when the absolute value of the change per minute of any battery cell reaches or exceeds the preset dynamic compensation activation temperature change threshold, and the temperature change direction indicated by the train tunnel entry / exit indicator signal is consistent with the direction of the change per minute, activate the dynamic compensation mode, output the filtered temperature change rate as the battery cell temperature change rate in the dynamic compensation mode, and lock and maintain the dynamic compensation mode until the preset minimum duration ends.

[0008] Preferably, in step S20, the step of performing an internal temperature prediction task based on the battery cell temperature change rate under the dynamic compensation mode and the corresponding surface temperature sampling value, using a heat conduction recursion and exponential weighted prediction mechanism, and outputting the predicted internal temperature of the battery cell, specifically includes: Step S201: Receive the battery cell temperature change rate and the corresponding surface temperature sampling value in the dynamic compensation mode output in step S10, take the internal temperature estimate value of the previous sampling time as the initial value for recursion, and perform heat conduction recursion on the surface temperature sampling value at the current sampling time according to the preset battery cell thermal time constant to obtain the internal temperature estimate value at the current sampling time. Step S202: Store the internal temperature estimates of the same battery cell at the most recent multiple sampling times to form an internal temperature estimation time series, and use the exponentially weighted sliding window least squares method to fit the internal temperature estimation time series to obtain the first predicted internal temperature corresponding to the first time period in the future and the second predicted internal temperature corresponding to the second time period in the future. Step S203: Read the train tunnel entry / exit indicator signal. When the train tunnel entry / exit indicator signal indicates that the train has entered the tunnel, a preset tunnel entry temperature bias is added to the first predicted internal temperature and the second predicted internal temperature. When the train tunnel entry / exit indicator signal indicates that the train has exited the tunnel, a preset tunnel temperature bias is added to the first predicted internal temperature and the second predicted internal temperature. When the train tunnel entry / exit indicator signal indicates that no tunnel entry / exit state switch has occurred, no tunnel direction bias is added to obtain the predicted internal temperature of the battery cell.

[0009] Preferably, step S202, the step of fitting the internal temperature estimation time series with a temperature trend using the exponentially weighted sliding window least squares method, specifically includes: Using the current sampling time as the zero point, the estimated internal temperature values ​​corresponding to the most recent sampling times are arranged in order from the closest to the furthest from the current sampling time; According to the preset forgetting factor, a larger fitting weight is assigned to the internal temperature estimate that is closer to the current sampling time, and a smaller fitting weight is assigned to the internal temperature estimate that is farther from the current sampling time. By fitting a straight line of temperature change over time with the objective of minimizing the weighted sum of squared residuals, the slope and intercept of the temperature change fitting are obtained. Using the temperature change fitting slope and the temperature change fitting intercept, the first predicted internal temperature corresponding to the first future time period and the second predicted internal temperature corresponding to the second future time period are extrapolated respectively.

[0010] Preferably, step S30, based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, employs a two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism to perform the feedforward compensation voltage calculation task and outputs the feedforward compensation voltage of each battery cell, specifically includes: Step S301: Place the first Predicted internal temperature of individual battery cells and rate of temperature change Substitute into the two-dimensional dynamic compensation coefficient function:

[0011] Calculation yields the first Dynamic temperature compensation coefficient of individual battery cells In the formula, This refers to the serial number of the individual battery cell. As the benchmark compensation coefficient, This is a correction factor for the absolute value of temperature. This is a correction factor for the rate of temperature change. For the first Predicted internal temperature of each individual battery cell. For the preset reference temperature, For the first The rate of temperature change of each individual battery cell; Step S302: Generate the first according to the following formula Initial feedforward compensation voltage of each battery cell :

[0012] In the formula, For the first The initial feedforward compensation voltage of each battery cell For rate direct feedforward coefficients; Step S303: Perform amplitude limiting and rate of change limiting processing on the initial feedforward compensation voltage to obtain the feedforward compensation voltage of the corresponding battery cell.

[0013] Preferably, step S40, which involves acquiring the real-time voltage of each battery cell, and based on the real-time voltage and feedforward compensation voltage of each battery cell, performing a time-varying equalization threshold construction task using a time-varying equalization threshold mapping mechanism, and outputting the upper threshold of the time-varying equalization voltage for each battery cell, specifically includes: Step S401: Collect the real-time voltage of each battery cell at the current moment, and average the real-time voltage of all battery cells to obtain the average real-time voltage. Step S402: Input the real-time average voltage, the preset maximum allowable voltage deviation value, and the feedforward compensation voltage of each battery cell output in step S30 into the time-varying equalization threshold mapping table to generate the time-varying equalization voltage upper threshold for each battery cell; wherein, the preset maximum allowable voltage deviation value is used to limit the maximum allowable voltage dispersion range between battery cells in the same battery pack. Step S403: For battery cells whose predicted internal temperature is higher than the lowest predicted internal temperature in the battery pack and the difference exceeds the preset predicted temperature difference threshold under dynamic compensation mode, the difference is matched with the preset predicted temperature difference level table to determine the predicted temperature difference level; the predicted equalization current setting value is determined according to the predicted temperature difference level, and the predicted equalization current setting value is written into the equalization control cache of the corresponding battery cell for use when bypass equalization discharge control is executed in step S50.

[0014] Preferably, step S50, which involves performing bypass equalization discharge control and dynamic compensation exit determination based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, and outputting a dynamic compensation mode exit confirmation signal, specifically includes: Step S501: Compare the real-time voltage of each battery cell with the corresponding time-varying equalization voltage upper threshold according to the preset equalization judgment cycle; when the real-time voltage of any battery cell is higher than the corresponding time-varying equalization voltage upper threshold, determine the difference between the real-time voltage and the corresponding time-varying equalization voltage upper threshold as the real-time voltage excess, open the bypass equalization discharge branch corresponding to the battery cell, and adjust the equalization current duty cycle according to the real-time voltage excess. Step S502: When the absolute value of the temperature change rate of all battery cells is lower than the preset dynamic compensation exit temperature change threshold within the preset exit observation time, and the train is not in the preset temperature change area, it is determined that the dynamic compensation mode exit condition is met, and a dynamic compensation mode exit candidate signal is generated. Step S503: After receiving the dynamic compensation mode exit candidate signal, perform first-order hysteresis smooth attenuation processing on the feedforward compensation voltage of each battery cell output in step S30, so that the feedforward compensation voltage of each battery cell gradually attenuates to the preset dynamic compensation final value, and use the temperature prediction residual in this dynamic compensation cycle to correct the temperature change rate correction factor online. After completing the online correction, output the dynamic compensation mode exit confirmation signal.

[0015] The present invention also provides a battery equalization control system for urban rail trains based on dynamic temperature compensation, the system comprising: The dynamic compensation activation module is used to obtain the surface temperature sampling value of each battery cell in the urban rail train battery pack, and to execute the dynamic compensation mode activation task based on the surface temperature sampling value using temperature change rate calculation and preset temperature change threshold triggering mechanism, and output the battery cell temperature change rate under dynamic compensation mode. The internal temperature prediction module is used to perform the internal temperature prediction task based on the temperature change rate of the battery cell under the dynamic compensation mode and the corresponding surface temperature sampling value, and to output the predicted internal temperature of the battery cell. The feedforward compensation voltage generation module is used to perform feedforward compensation voltage calculation tasks based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, and outputs the feedforward compensation voltage of each battery cell. The time-varying equalization threshold construction module is used to obtain the real-time voltage of each battery cell. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, the time-varying equalization threshold construction task is performed using a time-varying equalization threshold mapping mechanism, and the time-varying equalization voltage upper threshold of each battery cell is output. The equalization execution and exit determination module is used to perform bypass equalization discharge control and dynamic compensation exit determination based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, and output a dynamic compensation mode exit confirmation signal.

[0016] The present invention also provides a dynamic temperature compensation-based urban rail train battery equalization control device, the dynamic temperature compensation-based urban rail train battery equalization control device comprising: a memory, a processor, and a dynamic temperature compensation-based urban rail train battery equalization control program stored in the memory and executable on the processor, the dynamic temperature compensation-based urban rail train battery equalization control program implementing the above method when executed by the processor.

[0017] The present invention also provides a computer program product, the computer program product including a dynamic temperature compensation-based urban rail train battery balancing control program, which implements the above method when executed by a processor.

[0018] The beneficial effects of this invention are as follows: This invention uses temperature change rate calculation and dynamic threshold triggering mechanism, combined with train tunnel entry and exit sign signals for directional consistency judgment, to reliably activate dynamic compensation mode when the temperature change rate reaches 5℃ / min and matches the working condition direction. This avoids false triggering caused by sensor noise or short-term disturbances, and provides accurate temperature change trend input for subsequent internal temperature prediction and voltage compensation, ensuring timely activation of dynamic compensation.

[0019] By employing a weighted linear prediction mechanism based on a heat conduction model and a two-dimensional dynamic compensation coefficient generation and rate feedforward mechanism, temperature prediction and compensation voltage calculation are performed before the actual voltage change occurs. This allows the equalization threshold to dynamically fluctuate in real time with temperature changes, overcoming the lag problem of surface temperature sampling. Simultaneously, the time-varying equalization threshold mapping mechanism and the pre-equalization current based on predicted temperature differences intervene before voltage differences occur. Combined with smooth exit and online parameter correction, this effectively suppresses individual cell voltage overshoot caused by drastic temperature changes, keeping the individual cell voltage difference within a relatively small range. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the first embodiment of a battery balancing control method for urban rail trains based on dynamic temperature compensation according to the present invention. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: As Figure 1 The diagram shown is a flowchart of the first embodiment of a battery equalization control method for urban rail trains based on dynamic temperature compensation according to the present invention. The first embodiment of the battery equalization control method for urban rail trains based on dynamic temperature compensation according to the present invention is presented.

[0024] In the first embodiment, the method for equalizing the battery of an urban rail train based on dynamic temperature compensation includes: Step S10: Obtain the surface temperature sampling value of each battery cell in the urban rail train battery pack, and execute the dynamic compensation mode activation task based on the surface temperature sampling value using temperature change rate calculation and preset temperature change threshold triggering mechanism, and output the battery cell temperature change rate under dynamic compensation mode. The surface temperature sampling value of each battery cell refers to the temperature data continuously collected by temperature sensors installed on the side of the casing or at the thermal coupling position of each cell within the urban rail train's battery pack, according to a preset fixed sampling period. The surface temperature sampling value needs to be saved synchronously with the battery cell serial number, sampling time, and train operating condition indicator to ensure that temperature changes of the same cell at adjacent sampling times can be tracked. The temperature change rate calculation and preset temperature change threshold triggering mechanism converts the difference between adjacent sampling values ​​into a change per unit time, then performs median filtering and first-order hysteresis filtering on multiple consecutive changes, and finally combines the train tunnel entry / exit indicator signal to determine whether the direction of temperature change is consistent with the actual operating condition. Only when the temperature change rate reaches the preset activation condition and the direction judgment is valid is the dynamic compensation mode activated, and the filtered temperature change rate is output as the battery cell temperature change rate in the dynamic compensation mode.

[0025] The temperature change rate output at this stage is not an isolated alarm value, but rather a combined driving force for subsequent internal temperature prediction and feedforward voltage compensation. By locking the shortest duration when the dynamic compensation mode is activated, the system can avoid repeated switching of the compensation mode caused by the temperature change rate fluctuating around the threshold. By retaining the independent rate of each individual cell, subsequent steps can identify the differences between cells within the same battery pack caused by different installation locations, air duct obstructions, and thermal radiation conditions. Therefore, step S20 obtains an effective temperature change trend that has undergone operating condition verification and filtering, rather than the raw temperature difference that is easily affected by sensor spikes.

[0026] Fixed temperature compensation methods typically only read the absolute value of the current temperature, or trigger compensation immediately when the temperature change rate exceeds a single threshold, without considering the actual directional changes caused by trains entering or exiting tunnels, underground platforms, or open-air sections. Urban rail trains experience traction current disturbances, sensor contact differences, and localized airflow changes within the cabin during operation; relying solely on a single temperature jump can easily lead to misjudgments. The above processing places the filtered rate, temperature change threshold, and train operating direction under the same trigger condition, making the dynamic compensation mode closer to real-world rapid temperature change events and reducing the likelihood of premature compensation under short-term thermal noise.

[0027] In a scenario where a train enters an underground tunnel from an elevated section during summer, the surface temperature of the battery compartment in a certain carriage continuously decreases over multiple 10-second sampling periods. One battery cell near the door drops from 44°C to 38°C. The system first calculates the temperature change rate using continuous sampling values, then uses median filtering to remove individual abnormal sampling points, and uses first-order hysteresis filtering to smooth the rate curve. When the smoothed change per minute reaches a preset activation temperature change threshold, and the train's tunnel entry / exit sign indicates the current direction is towards tunnel cooling, the dynamic compensation mode is activated and locked. The temperature change rate of this single cell then proceeds to step S20 to predict its internal temperature change over a future period.

[0028] Step S20: Based on the temperature change rate of the battery cell under the dynamic compensation mode and the corresponding surface temperature sampling value, the internal temperature prediction task is performed using a heat conduction recursion and exponential weighted prediction mechanism, and the predicted internal temperature of the battery cell is output. The predicted internal temperature of a battery cell refers to the estimation of its internal thermal state based on the rate of temperature change of the battery cell under dynamic compensation mode and the corresponding surface temperature sampling value, when the internal temperature of the cell cannot be directly measured. Thermal conduction recursion uses the internal temperature estimate from the previous sampling moment as the starting point and updates the current internal temperature estimate by combining the current surface temperature sampling value and a preset battery cell thermal time constant. Exponential weighted prediction stores the internal temperature estimates from the most recent sampling moments and gives higher weight to estimates closer to the current moment in trend fitting. If the train tunnel entry / exit sign indicates a tunnel entry or exit status switch, a temperature bias in the corresponding direction is also added to the predicted internal temperature.

[0029] After this processing, the output predicted internal temperature of the battery cell simultaneously includes three types of information: surface temperature, thermal inertia, and the trend of sudden changes in operating conditions. The surface temperature reflects the actual reading of the outer casing sensor, the thermal time constant describes the lag in the transfer of temperature from the outer casing to the internal temperature, and the exponentially weighted trend fitting is used to determine the trend of the internal temperature in the first and second time periods. This result is directly used as the temperature input for calculating the feedforward compensation voltage in step S30, so that the compensation voltage no longer passively waits for the surface temperature to change completely before adjusting, but participates in the equalization control as soon as the internal temperature trend is formed.

[0030] Traditional battery equalization control often uses surface temperature as the compensation temperature or a fixed empirical value to approximate the internal temperature. When a train moves from a low-temperature tunnel into a high-temperature open-air section, there is a time difference between the surface temperature sensor and the internal thermal state of the battery cell. Directly using the surface temperature will cause a lag in the adjustment of the compensation threshold. During reverse cooling, the surface temperature may drop first while the internal temperature remains high, causing the compensation to weaken prematurely. Thermal conduction recursion and exponential weighted prediction incorporate temperature history and thermal inertia into the same estimation chain, which can reduce threshold misadjustment caused by surface temperature lag.

[0031] In a scenario where a train exits an underground station and enters an open-air, high-temperature section, the surface temperature of a battery cell's casing remains at 34°C, but the estimated internal temperature over the last five sampling times has been steadily increasing. Exponentially weighted prediction places greater emphasis on the temperature rise trend reflected in the latest sampling point and extrapolates the internal temperature for the next 10 and 20 seconds. If the line marker simultaneously indicates that the train is exiting a tunnel, the system superimposes a temperature bias in the tunnel direction onto the predicted internal temperature, making the prediction more closely approximate the upcoming thermal environment changes. After this predicted internal temperature is fed into step S30, the feedforward compensation voltage can be adjusted in advance, rather than waiting until the cell voltage has significantly deviated before adjustment.

[0032] Step S30: Based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, the feedforward compensation voltage calculation task is performed by using a two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism, and the feedforward compensation voltage of each battery cell is output. The two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism refers to simultaneously considering the predicted internal temperature of the battery cell and the temperature change rate under dynamic compensation mode when generating the feedforward compensation voltage. The two-dimensional dynamic compensation coefficient is jointly determined by the reference compensation coefficient, the absolute temperature correction factor, and the temperature change rate correction factor. The absolute temperature correction factor reflects the degree to which the predicted internal temperature deviates from the preset reference temperature, while the temperature change rate correction factor reflects the trend of rapid temperature increase or decrease. The initial feedforward compensation voltage is then calculated by superimposing the feedforward component directly formed by the temperature change rate onto the dynamic compensation coefficient applied to the temperature deviation. After amplitude limiting and rate of change limiting processing, the feedforward compensation voltage for each battery cell is output.

[0033] The function of the feedforward compensation voltage is to convert the temperature trend into a correction value for the equalization threshold in advance. Cells with predicted high internal temperatures and rapid heating rates typically require earlier equalization intervention; cells with predicted low internal temperatures or significant cooling require avoiding unnecessary bypass discharge. Through limiting, the compensation voltage will not exceed the tolerance range of the equalization control hardware due to instantaneous prediction deviations; through rate-of-change limiting, the compensation voltage changes smoothly between adjacent sampling periods, preventing sudden jumps in the upper threshold of the time-varying equalization voltage constructed in step S40. This output transforms temperature compensation from a static correction into a feedforward control value that changes with the thermal state of the individual cells.

[0034] Fixed compensation coefficients can only express steady-state corrections after temperature deviates from the reference value, but cannot reflect the rate of temperature change. When urban rail trains enter and exit tunnels, the internal temperature of some individual units may be rising rapidly. Even if the current predicted internal temperature has not yet reached a high-temperature level, it is necessary to lower the subsequent equilibrium control criteria in advance; if fixed coefficients are still used, the compensation action will lag behind the voltage change. Two-dimensional dynamic compensation and rate feedforward incorporate both the absolute temperature quantity and the direction of temperature change into the compensation voltage generation process, enabling the feedforward compensation voltage to reflect the trend change in the early stages of rapid temperature change.

[0035] In a scenario where the temperature rises rapidly in an open-air high-temperature zone, the predicted internal temperature of a single unit near a ventilation dead zone is 42°C, with a temperature change rate of approximately 8°C per minute. The system first determines the steady-state compensation component based on the deviation of the predicted internal temperature from the reference temperature, and then forms an additional feedforward component based on the temperature rise rate. If the initial feedforward compensation voltage after the sum of the two exceeds a preset lower limit, it is output according to the limit value and gradually applied according to the allowable rate of change. In this way, the single unit obtains a strong feedforward compensation voltage before the voltage rises significantly, allowing step S40 to lower or adjust its time-varying equilibrium trigger standard.

[0036] Step S40: Obtain the real-time voltage of each battery cell. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, perform the time-varying equalization threshold construction task using the time-varying equalization threshold mapping mechanism, and output the time-varying equalization voltage upper threshold of each battery cell. The time-varying equalization threshold mapping mechanism refers to first obtaining the average real-time voltage of the battery pack after collecting the real-time voltage of each individual battery cell at the current moment, and then inputting the average real-time voltage, the preset maximum allowable voltage deviation value, and the feedforward compensation voltage of each individual battery cell output in step S30 into a mapping table to generate the time-varying equalization voltage upper threshold for each individual cell. This mapping table determines the correction method for the upper threshold of each individual cell based on the direction and amplitude of the feedforward compensation voltage. Simultaneously, in dynamic compensation mode, it compares the difference between the predicted internal temperature of each individual cell and the lowest predicted internal temperature in the group. When the difference exceeds the preset predicted temperature difference threshold, a predictive equalization current setting value is determined according to the predicted temperature difference level and written to the equalization control cache of the corresponding battery cell.

[0037] This stage formally transforms the temperature compensation results into voltage equalization criteria. The real-time average voltage provides the current voltage reference for the entire group, and the preset maximum allowable voltage deviation limits the allowable dispersion range within the same group. The feedforward compensation voltage enables different thermal states of individual cells to obtain different equalization trigger thresholds. After the predictive equalization current setting value is written to the cache, it can be directly called in step S50 when performing bypass equalization discharge, thus enabling small-current intervention in advance when the real-time voltage is just approaching the upper threshold or has not yet formed a significant over-limit. The output time-varying equalization voltage upper threshold corresponds one-to-one with each individual cell, avoiding the use of only a uniform threshold for the entire group.

[0038] Traditional equalization thresholds are typically derived by adding a fixed deviation to the average voltage of the entire group, applying the same criterion to all cells. However, in urban rail train battery packs, cell temperatures vary due to installation location, ventilation, and heat sources; high-temperature cells may require premature discharge, while low-temperature cells may not be suitable for early discharge. A uniform threshold cannot distinguish these thermal state differences, easily leading to delayed discharge in high-temperature cells or false discharge in low-temperature cells. By introducing feedforward compensation voltage and predicted temperature difference levels, the upper threshold for each cell can dynamically change according to its thermal state, and the triggering basis for bypass equalization is more closely aligned with the actual situation of each cell.

[0039] In a group of urban rail batteries, if the average real-time voltage within the group is approximately 3.62V and the maximum allowable voltage deviation is 25mV, cell A, due to its predicted internal temperature being significantly higher than the lowest predicted temperature within the group, is assigned a more aggressive balancing level by the mapping table; cell B, with a temperature close to the group average, maintains a more moderate threshold correction. The system writes the predictive balancing current setting value of cell A into the cache, causing step S50 to preferentially activate the bypass branch when its voltage approaches the corresponding upper threshold. This process ensures that high-temperature cells do not wait for the entire group to reach a uniform threshold before discharging, but are subject to balancing constraints in advance when temperature risks have already materialized.

[0040] Step S50: Based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, perform bypass equalization discharge control and dynamic compensation exit determination, and output a dynamic compensation mode exit confirmation signal. The bypass equalization discharge control and dynamic compensation exit determination refers to continuously comparing the real-time voltage of each battery cell with the corresponding time-varying equalization voltage upper threshold according to a preset equalization judgment cycle. If the real-time voltage of any cell is higher than the corresponding upper threshold, the system determines the difference between the two as the real-time voltage excess, activates the bypass equalization discharge branch of that cell, and adjusts the equalization current duty cycle according to the excess. The exit determination simultaneously checks whether the temperature change rate of all cells is lower than the preset exit temperature change threshold within the preset exit observation time, and whether the train has left the expected temperature change area such as tunnels and underground platforms; after the conditions are met, a dynamic compensation mode exit candidate signal is generated.

[0041] After exiting candidate signal generation, the system does not immediately clear the feedforward compensation voltage. Instead, it performs a first-order hysteresis smooth decay on the feedforward compensation voltage of each battery cell output in step S30, allowing the compensation voltage to gradually transition to the preset dynamic compensation final value. In this way, the time-varying equalization voltage upper threshold based on step S40 will also recover smoothly, preventing the bypass discharge branch from frequently switching on and off due to threshold abrupt changes. Simultaneously, the temperature prediction residual accumulated during this dynamic compensation cycle is used to correct compensation parameters such as the temperature change rate correction factor online, making the internal temperature prediction and feedforward compensation voltage generation more closely reflect the actual cell state during the next tunnel entry / exit or rapid temperature change.

[0042] Conventional control systems often use fixed delays or single temperature thresholds to determine compensation termination, neglecting the continuous occurrence of tunnels, underground platforms, and open-air sections along the train track. If termination occurs as soon as the temperature begins to decrease, the system will reactivate when the train re-enters the temperature-changing region shortly afterward, causing repeated impacts on the threshold and balancing current. Conversely, if termination occurs too late, dynamic compensation will negatively affect the balancing criteria for an extended period under steady-state conditions. This approach combines temperature change rate stability, track temperature-changing regions, and feedforward compensation smoothing attenuation to ensure that the termination action aligns with the actual operating environment. Furthermore, residual corrections are used to adjust compensation parameters, reducing model bias caused by battery aging and thermal characteristic drift during long-term operation.

[0043] In the scenario where the train leaves the tunnel and enters stable operation on the elevated track, the control unit continuously monitors that the temperature change rate of all battery cells has fallen below the preset exit temperature threshold, and the line information indicates that there are no tunnels or underground platforms in the near future. The system first generates an exit candidate signal, and then gradually decays the feedforward compensation voltage of each cell to the steady-state compensation value using a first-order hysteresis method; for cells that have previously activated bypass discharge, the equalization current duty cycle gradually decreases as the real-time voltage excess decreases. After the dynamic compensation cycle ends, the system updates the relevant compensation parameters based on the residual between the predicted internal temperature of this cycle and the subsequent estimated temperature, and outputs a dynamic compensation mode exit confirmation signal, indicating that the equalization control has smoothly returned to the normal state.

[0044] Example 2: Furthermore, the present invention provides a dynamic temperature compensation-based urban rail train battery balancing control system, employing a dynamic temperature compensation-based urban rail train battery balancing control method from the above embodiments, which can solve the technical problem of dynamic temperature compensation-based urban rail train battery balancing control. The beneficial effects of the dynamic temperature compensation-based urban rail train battery balancing control system provided by the present invention are the same as those of the dynamic temperature compensation-based urban rail train battery balancing control method provided in the above embodiments, and other technical features in the dynamic temperature compensation-based urban rail train battery balancing control system are the same as those disclosed in the above embodiments, and will not be repeated here.

[0045] Example 3: This invention provides a dynamic temperature compensation-based urban rail train battery balancing control device. The device includes at least one processor and a memory communicatively connected to the processor. The memory stores instructions executable by the processor, which are then executed to enable the processor to perform the dynamic temperature compensation-based urban rail train battery balancing control method described in Example 1. The dynamic temperature compensation-based urban rail train battery balancing control device in this invention can include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. This dynamic temperature compensation-based urban rail train battery balancing control device is merely an example and should not limit the functionality or scope of the invention. A dynamic temperature-compensated urban rail train battery balancing control device may include a processing unit (e.g., a central processing unit, a graphics processing unit, etc.) that can perform various appropriate actions and processes according to a program stored in a read-only memory or a program loaded from a storage device into a random access memory. The random access memory also stores various programs and data required for the operation of the dynamic temperature-compensated urban rail train battery balancing control device. The processing unit, read-only memory, and random access memory are interconnected via a bus. An I / O interface is also connected to the bus. Typically, the following systems can be connected to the I / O interface: input devices including touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices including liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices including magnetic tapes, hard disks, etc.; and communication devices. The communication device allows the dynamic temperature-compensated urban rail train battery balancing control device to communicate wirelessly or wiredly with other devices to exchange data. Although a dynamic temperature-compensated urban rail train battery balancing control device with various systems has been described, it should be understood that implementation or possession of all the described systems is not required. It can be implemented alternatively or with more or fewer systems.

[0046] Example 4: This invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method for equalizing urban rail train batteries based on dynamic temperature compensation. The computer program product provided by this invention can solve the technical problem of equalizing urban rail train batteries based on dynamic temperature compensation. Compared with the prior art, the beneficial effects of the computer program product provided by this invention are the same as those of the above-described method for equalizing urban rail train batteries based on dynamic temperature compensation, and will not be repeated here.

[0047] In particular, according to the embodiments disclosed in this invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from a storage device, or installed from a read-only memory. When the computer program is executed by a processing device, it performs the functions defined in the methods of the embodiments disclosed in this invention.

[0048] It should be understood that the various parts disclosed in this invention can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0049] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A battery equalization control method for urban rail trains based on dynamic temperature compensation, characterized in that, The methods include: Step S10: Obtain the surface temperature sampling value of each battery cell in the urban rail train battery pack, and execute the dynamic compensation mode activation task based on the surface temperature sampling value using temperature change rate calculation and preset temperature change threshold triggering mechanism, and output the battery cell temperature change rate under dynamic compensation mode. Step S20: Based on the temperature change rate of the battery cell under the dynamic compensation mode and the corresponding surface temperature sampling value, the internal temperature prediction task is performed using a heat conduction recursion and exponential weighted prediction mechanism, and the predicted internal temperature of the battery cell is output. Step S30: Based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, the feedforward compensation voltage calculation task is performed by using a two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism, and the feedforward compensation voltage of each battery cell is output. Step S40: Obtain the real-time voltage of each battery cell. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, perform the time-varying equalization threshold construction task using the time-varying equalization threshold mapping mechanism, and output the time-varying equalization voltage upper threshold of each battery cell. Step S50: Based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, perform bypass equalization discharge control and dynamic compensation exit determination, and output a dynamic compensation mode exit confirmation signal.

2. The method for equalizing the battery of urban rail trains based on dynamic temperature compensation as described in claim 1, characterized in that, Step S10 involves obtaining surface temperature sampling values ​​of each battery cell within the urban rail train's battery pack, performing dynamic compensation mode activation based on the surface temperature sampling values ​​using temperature change rate calculation and a preset temperature change threshold triggering mechanism, and outputting the battery cell temperature change rate under dynamic compensation mode. Specifically, this includes: Step S101: Collect surface temperature sampling values ​​of each battery cell at multiple sampling times according to a preset fixed sampling period, determine the order of the multiple sampling times as the sampling time sequence, and form a surface temperature sequence corresponding to each battery cell based on the sampling time sequence. Step S102: Calculate the difference between the surface temperature sampling values ​​of the same battery cell at adjacent sampling times, and convert them into the instantaneous temperature change rate according to the preset fixed sampling period; perform median filtering and first-order hysteresis filtering on multiple consecutive instantaneous temperature change rates in sequence to obtain the filtered temperature change rate. Step S103: Convert the filtered temperature change rate into a change per minute and acquire the train tunnel entry / exit indicator signal; when the absolute value of the change per minute of any battery cell reaches or exceeds the preset dynamic compensation activation temperature change threshold, and the temperature change direction indicated by the train tunnel entry / exit indicator signal is consistent with the direction of the change per minute, activate the dynamic compensation mode, output the filtered temperature change rate as the battery cell temperature change rate in the dynamic compensation mode, and lock and maintain the dynamic compensation mode until the preset minimum duration ends.

3. The method for equalizing the battery of urban rail trains based on dynamic temperature compensation as described in claim 1, characterized in that, In step S20, based on the rate of change of battery cell temperature under the dynamic compensation mode and the corresponding surface temperature sampling value, an internal temperature prediction task is performed using a heat conduction recursion and exponential weighted prediction mechanism, and the predicted internal temperature of the battery cell is output. This step specifically includes: Step S201: Receive the battery cell temperature change rate and the corresponding surface temperature sampling value in the dynamic compensation mode output in step S10, take the internal temperature estimate value of the previous sampling time as the initial value for recursion, and perform heat conduction recursion on the surface temperature sampling value at the current sampling time according to the preset battery cell thermal time constant to obtain the internal temperature estimate value at the current sampling time. Step S202: Store the internal temperature estimates of the same battery cell at the most recent multiple sampling times to form an internal temperature estimation time series, and use the exponentially weighted sliding window least squares method to fit the internal temperature estimation time series to obtain the first predicted internal temperature corresponding to the first time period in the future and the second predicted internal temperature corresponding to the second time period in the future. Step S203: Read the train tunnel entry / exit indicator signal. When the train tunnel entry / exit indicator signal indicates that the train has entered the tunnel, a preset tunnel entry temperature bias is added to the first predicted internal temperature and the second predicted internal temperature. When the train tunnel entry / exit indicator signal indicates that the train has exited the tunnel, a preset tunnel temperature bias is added to the first predicted internal temperature and the second predicted internal temperature. When the train tunnel entry / exit indicator signal indicates that no tunnel entry / exit state switch has occurred, no tunnel direction bias is added to obtain the predicted internal temperature of the battery cell.

4. The method for equalizing the battery of urban rail trains based on dynamic temperature compensation as described in claim 3, characterized in that, Step S202, which involves fitting the internal temperature estimation time series to a temperature trend using the exponentially weighted sliding window least squares method, specifically includes: Using the current sampling time as the zero point, the estimated internal temperature values ​​corresponding to the most recent sampling times are arranged in order from the closest to the furthest from the current sampling time; According to the preset forgetting factor, a larger fitting weight is assigned to the internal temperature estimate that is closer to the current sampling time, and a smaller fitting weight is assigned to the internal temperature estimate that is farther from the current sampling time. The temperature-time line is fitted with the objective of minimizing the weighted sum of squared residuals to obtain the fitted slope and intercept of the temperature change. Using the temperature change fitting slope and the temperature change fitting intercept, the first predicted internal temperature corresponding to the first future time period and the second predicted internal temperature corresponding to the second future time period are extrapolated respectively.

5. The method for equalizing the battery of urban rail trains based on dynamic temperature compensation as described in claim 1, characterized in that, Step S30, based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, employs a two-dimensional dynamic compensation coefficient generation and rate feedforward calculation mechanism to perform the feedforward compensation voltage calculation task and outputs the feedforward compensation voltage of each battery cell. Specifically, this includes: Step S301: Place the first Predicted internal temperature of individual battery cells and rate of temperature change Substitute into the two-dimensional dynamic compensation coefficient function: Calculation yields the first Dynamic temperature compensation coefficient of individual battery cells In the formula, This refers to the serial number of the individual battery cell. As the benchmark compensation coefficient, This is a correction factor for the absolute value of temperature. This is a correction factor for the rate of temperature change. For the first Predicted internal temperature of each individual battery cell. For the preset reference temperature, For the first The rate of temperature change of each individual battery cell; Step S302: Generate the first according to the following formula Initial feedforward compensation voltage of each battery cell : In the formula, For the first The initial feedforward compensation voltage of each battery cell For rate direct feedforward coefficients; Step S303: Perform amplitude limiting and rate of change limiting processing on the initial feedforward compensation voltage to obtain the feedforward compensation voltage of the corresponding battery cell.

6. The method for equalization control of urban rail train batteries based on dynamic temperature compensation as described in claim 1, characterized in that, In step S40, the real-time voltage of each battery cell is obtained. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, a time-varying equalization threshold construction task is performed using a time-varying equalization threshold mapping mechanism, and the upper threshold of the time-varying equalization voltage of each battery cell is output. This step specifically includes: Step S401: Collect the real-time voltage of each battery cell at the current moment, and average the real-time voltage of all battery cells to obtain the average real-time voltage. Step S402: Input the real-time average voltage, the preset maximum allowable voltage deviation value, and the feedforward compensation voltage of each battery cell output in step S30 into the time-varying equalization threshold mapping table to generate the time-varying equalization voltage upper threshold for each battery cell; wherein, the preset maximum allowable voltage deviation value is used to limit the maximum allowable voltage dispersion range between battery cells in the same battery pack. Step S403: For battery cells whose predicted internal temperature is higher than the lowest predicted internal temperature in the battery pack and the difference exceeds the preset predicted temperature difference threshold under dynamic compensation mode, the difference is matched with the preset predicted temperature difference level table to determine the predicted temperature difference level; the predicted equalization current setting value is determined according to the predicted temperature difference level, and the predicted equalization current setting value is written into the equalization control cache of the corresponding battery cell for use when bypass equalization discharge control is executed in step S50.

7. The method for equalizing the battery of urban rail trains based on dynamic temperature compensation as described in claim 5, characterized in that, Step S50, which involves performing bypass equalization discharge control and dynamic compensation exit determination based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, and outputting a dynamic compensation mode exit confirmation signal, specifically includes: Step S501: Compare the real-time voltage of each battery cell with the corresponding time-varying equalization voltage upper threshold according to the preset equalization judgment cycle; when the real-time voltage of any battery cell is higher than the corresponding time-varying equalization voltage upper threshold, determine the difference between the real-time voltage and the corresponding time-varying equalization voltage upper threshold as the real-time voltage excess, open the bypass equalization discharge branch corresponding to the battery cell, and adjust the equalization current duty cycle according to the real-time voltage excess. Step S502: When the absolute value of the temperature change rate of all battery cells is lower than the preset dynamic compensation exit temperature change threshold within the preset exit observation time, and the train is not in the preset temperature change area, it is determined that the dynamic compensation mode exit condition is met, and a dynamic compensation mode exit candidate signal is generated. Step S503: After receiving the dynamic compensation mode exit candidate signal, perform first-order hysteresis smooth attenuation processing on the feedforward compensation voltage of each battery cell output in step S30, so that the feedforward compensation voltage of each battery cell gradually attenuates to the preset dynamic compensation final value, and use the temperature prediction residual in this dynamic compensation cycle to correct the temperature change rate correction factor online. After completing the online correction, output the dynamic compensation mode exit confirmation signal.

8. A dynamic temperature compensation-based battery balancing control system for urban rail trains, applied to the dynamic temperature compensation-based battery balancing control method for urban rail trains as described in any one of claims 1 to 7, characterized in that, The system includes: The dynamic compensation activation module is used to obtain the surface temperature sampling value of each battery cell in the urban rail train battery pack, and to execute the dynamic compensation mode activation task based on the surface temperature sampling value using temperature change rate calculation and preset temperature change threshold triggering mechanism, and output the battery cell temperature change rate under dynamic compensation mode. The internal temperature prediction module is used to perform the internal temperature prediction task based on the temperature change rate of the battery cell under the dynamic compensation mode and the corresponding surface temperature sampling value, and to output the predicted internal temperature of the battery cell. The feedforward compensation voltage generation module is used to perform feedforward compensation voltage calculation tasks based on the predicted internal temperature of the battery cell and the rate of temperature change of the battery cell under the dynamic compensation mode, and outputs the feedforward compensation voltage of each battery cell. The time-varying equalization threshold construction module is used to obtain the real-time voltage of each battery cell. Based on the real-time voltage of each battery cell and the feedforward compensation voltage of each battery cell, the time-varying equalization threshold construction task is performed using a time-varying equalization threshold mapping mechanism, and the time-varying equalization voltage upper threshold of each battery cell is output. The equalization execution and exit determination module is used to perform bypass equalization discharge control and dynamic compensation exit determination based on the comparison result between the real-time voltage of each battery cell and the corresponding time-varying equalization voltage upper threshold, and output a dynamic compensation mode exit confirmation signal.

9. A battery balancing control device for urban rail trains based on dynamic temperature compensation, characterized in that, The urban rail train battery balancing control device based on dynamic temperature compensation includes: a memory, a processor, and a dynamic temperature compensation-based urban rail train battery balancing control program stored in the memory and executable on the processor. When the dynamic temperature compensation-based urban rail train battery balancing control program is executed by the processor, it implements the dynamic temperature compensation-based urban rail train battery balancing control method according to any one of claims 1 to 7.

10. A computer program product, characterized in that, The computer program product includes a dynamic temperature compensation-based urban rail train battery balancing control program, which, when executed by a processor, implements a dynamic temperature compensation-based urban rail train battery balancing control method according to any one of claims 1 to 7.

Images