A lithium battery pack charging and discharging control method, system and lithium battery pack

Abstract

This application discloses a charging and discharging control method, system, and lithium battery pack, relating to the field of rechargeable battery discharging technology. The method includes: extracting current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cycle aging characteristics based on the loop current data of the target lithium battery pack, the terminal voltage of each individual cell, and surface temperature; calculating the instantaneous load rate, terminal voltage range, and temperature gradient vector; setting a reference pulse frequency based on the temperature gradient vector in fast charging or high-rate discharging scenarios; correcting the reference pulse frequency based on the cumulative number of cycles; and dynamically correcting the reference pulse duty cycle based on the terminal voltage range. The corrected pulse frequency and duty cycle are used to control the equalization switch, generating and outputting the current charging and discharging control strategy for the lithium battery pack. This solves the technical problem of existing technologies struggling to achieve safe, efficient, and adaptive equalization under high-rate charging and discharging conditions.

Description

Technical Field

[0001] This application relates to the field of battery charging and discharging technology, specifically to a charging and discharging control method, system, and lithium battery pack. Background Technology

[0002] Lithium-ion battery packs are widely used due to their advantages such as high energy density, long cycle life and low self-discharge rate. However, in actual use, due to differences in manufacturing processes, changes in the usage environment and uneven aging, the individual cells in a lithium-ion battery pack are prone to inconsistencies in voltage, temperature and capacity during charging and discharging, which leads to overall performance degradation, reduction in usable capacity and even safety risks such as thermal runaway.

[0003] In existing technologies, passive balancing or active balancing strategies with fixed parameters are typically used to manage lithium battery packs. Passive balancing achieves voltage consistency through resistor energy dissipation, but it suffers from significant energy waste and slow balancing speed. While traditional active balancing can achieve energy transfer, its control parameters are mostly preset fixed values, making it difficult to adapt to dynamic changes in battery state under different operating conditions. Especially in high-load scenarios such as fast charging or high-rate discharging, it is impossible to balance balancing efficiency and battery safety.

[0004] In addition, existing methods rarely take into account the influence of multi-dimensional characteristics such as temperature field distribution, voltage dispersion and cyclic aging on equalization control, resulting in a lack of adaptability and robustness in the control strategy.

[0005] To address the aforementioned issues, this application proposes an adaptive charge-discharge control method based on multi-source state feature fusion. By extracting key features such as current rate, voltage dispersion, temperature field distribution, and cumulative cycle aging in real time, the instantaneous load rate, terminal voltage range, and temperature gradient vector are dynamically calculated. Based on this, the pulse frequency and duty cycle are modified according to the scenario, thereby improving balancing efficiency and system energy efficiency while ensuring battery safety. Summary of the Invention

[0006] This application provides a method, system, and lithium battery pack for controlling the charging and discharging of a lithium battery pack, which solves the technical problem that existing technologies struggle to achieve safe, efficient, and adaptive equalization under high-rate charging and discharging conditions.

[0007] The technical solution to the above-mentioned technical problems in this application is as follows: In a first aspect, this application provides a charging and discharging control method for a lithium battery pack, the method comprising: Based on the loop current data of the target lithium battery pack, the terminal voltage and surface temperature of each individual cell, the current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cycle aging characteristics are extracted respectively. Based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics, the instantaneous load rate, terminal voltage range, and temperature gradient vector are calculated. When the instantaneous load rate exceeds a preset threshold, it is identified as a fast charging scenario or a high-rate discharge scenario. A reference pulse frequency is set according to the lowest temperature value in the temperature gradient vector, and the reference pulse frequency is aged and corrected according to the cumulative number of cycles to obtain a corrected pulse frequency. The reference pulse duty cycle is set according to the instantaneous load rate, and the reference pulse duty cycle is dynamically corrected according to the terminal voltage range to obtain the corrected pulse duty cycle. The equalization switch is controlled by the corrected pulse frequency and the corrected pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

[0008] Secondly, this application provides a charging and discharging control system for a lithium battery pack, comprising: The data acquisition module is used to extract current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cycle aging characteristics based on the loop current data of the target lithium battery pack, the terminal voltage of each individual cell, and the surface temperature. The state calculation module is used to calculate the instantaneous load rate, terminal voltage range, and temperature gradient vector based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics. The frequency adaptive module is used to identify a fast charging scenario or a high-rate discharge scenario when the instantaneous load rate exceeds a preset threshold, set a reference pulse frequency according to the lowest temperature value in the temperature gradient vector, and perform aging correction on the reference pulse frequency according to the cumulative number of cycles to obtain a corrected pulse frequency. The duty cycle adaptive module is used to set the reference pulse duty cycle according to the instantaneous load rate, and to dynamically correct the reference pulse duty cycle according to the terminal voltage range to obtain the corrected pulse duty cycle. The strategy generation and output module is used to control the equalization switch with the correction pulse frequency and the correction pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

[0009] Thirdly, this application provides a lithium battery pack, comprising: The battery pack itself is composed of multiple individual cells connected in series or parallel. The equalization switch network, connected between individual cells, is used to perform active equalization during charging and discharging. A temperature sensing array is attached to the surface of each individual battery cell to collect surface temperature in real time. The current sensing unit is connected in series in the main circuit of the battery pack to collect circuit current data; A voltage sampling unit is connected in parallel across each individual cell to collect the voltage at each cell terminal. The controller is connected to the equalization switch network, the temperature sensor array, the current sensor unit, and the voltage sampling unit, respectively. The controller includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it implements the lithium battery pack charging and discharging control method in the first aspect.

[0010] This application provides one or more technical solutions, which have at least the following technical effects or advantages: This application provides a charging and discharging control method, system, and battery pack for lithium batteries. First, by integrating multi-dimensional state characteristics such as current rate, voltage dispersion, temperature field distribution, and cumulative cycle aging, a dynamic evaluation system coupled with actual operating conditions is constructed. Second, after identifying high-load scenarios such as fast charging or high-rate discharging, the pulse frequency is set based on the lowest temperature value in the temperature gradient vector, and a frequency aging correction mechanism based on the cycle life range is introduced. Simultaneously, the duty cycle is dynamically corrected in a segmented manner through the terminal voltage difference, achieving intelligent adjustment capabilities that maintain efficient operation under mild imbalance and enhance equalization intervention under severe imbalance. Furthermore, the generated pulse width modulation signal supports waveform symmetry switching and channel phase reversal control, which not only improves energy transfer efficiency but also effectively suppresses current spikes and electromagnetic interference caused by synchronous conduction of switching transistors. Finally, by real-time feedback of the individual cell voltage change rate and triggering protective frequency reduction or duty cycle reduction operations, the equalization efficiency and overall energy efficiency under high-rate charging and discharging scenarios are further improved while ensuring long-term reliable operation of the battery pack.

[0011] Through the above technical solution, this application effectively solves the contradiction between rigid balancing strategies, insufficient safety margin and energy efficiency loss in traditional lithium battery packs under complex operating conditions. Furthermore, by integrating a high-precision sensing unit and a controller with adaptive decision-making capabilities, the lithium battery pack can perceive the multidimensional heterogeneity of battery status in real time during operation. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic flowchart of a charging and discharging control method for a lithium battery pack provided in an embodiment of this application; Figure 2This is a schematic diagram of the structure of a lithium battery pack charging and discharging control system provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a lithium battery pack provided in an embodiment of this application.

[0014] The components represented by each number in the attached diagram are explained below: The system includes a data acquisition module 11, a state calculation module 12, a frequency adaptive module 13, a duty cycle adaptive module 14, a strategy generation and output module 15, a controller 600, a memory 610, a processor 620, and a computer program 611. Detailed Implementation

[0015] This application provides a method, system, and lithium battery pack for controlling the charging and discharging of a lithium battery pack, which addresses the technical problem that existing technologies struggle to achieve safe, efficient, and adaptive equalization under high-rate charging and discharging conditions.

[0016] Example 1, as Figure 1 As shown in the figure, this application provides a charging and discharging control method for a lithium battery pack, including: S10: Based on the loop current data of the target lithium battery pack, the terminal voltage and surface temperature of each individual cell, extract the current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cycle aging characteristics respectively. In this embodiment, the loop current data of the target lithium battery pack is collected by the current sensing unit of the target lithium battery pack, the terminal voltage of each individual cell is collected by the voltage sampling unit, and the surface temperature of each individual cell is collected by the temperature sensing array. Based on the above collected data, the current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cycle aging characteristics are extracted respectively.

[0017] Specifically, step S10 in the method includes: The loop current data is sampled using a sliding window, and the ratio of the average current within the window to the rated current is calculated as the current ratio feature. The terminal voltages of all individual cells are sorted in real time, and the difference between the maximum and minimum terminal voltages is calculated as the instantaneous voltage range. The root mean square value of the range sequence within a preset time window is used as the voltage dispersion feature. Spatial interpolation is performed on the surface temperature of all individual cells to generate a temperature field matrix, and the highest temperature, lowest temperature and average temperature in the temperature field matrix are extracted to form the temperature field distribution characteristics. Based on the charge and discharge history of the target lithium battery pack, the equivalent ampere-hour throughput of each deep charge and discharge cycle is accumulated. When the accumulated ampere-hour throughput reaches a preset cycle threshold, a cycle aging count is recorded to obtain the accumulated cycle aging characteristics.

[0018] In this embodiment of the application, firstly, the loop current data is sampled using a sliding window, for example, with a window length of 100 sampling points, i.e., a sampling period of 0.01 seconds. The ratio of the average current within the window to the rated current is calculated as a current ratio feature, wherein the rated current is the standard continuous operating current specified by the battery pack manufacturer.

[0019] For example, if the battery pack has a rated current of 100 amps and the average current in the current window is 200 amps, then the current rate characteristic is 2C.

[0020] Secondly, the terminal voltages of all individual cells are sorted in real time, and the difference between the maximum and minimum terminal voltages is calculated as the instantaneous voltage range. A preset time window is dynamically set according to the current change rate. For example, when the window length is 1 second, the root mean square value of the range sequence is used as the voltage dispersion feature. Since the equalization operation needs to be started when the battery pack range exceeds 20mV, the use of root mean square processing in this application can effectively suppress the interference of instantaneous measurement noise on the voltage dispersion assessment.

[0021] Next, spatial interpolation is performed on the surface temperature of all individual cells to generate a temperature field matrix. The highest, lowest, and average temperatures in the temperature field matrix are then extracted to form the temperature field distribution characteristics, which reflect the overall thermal state.

[0022] For example, when the battery pack consists of N cells arranged in an M×K array, the measured temperature can be bilinearly interpolated based on the position coordinates (i,j) of each cell to generate a continuous two-dimensional temperature field matrix T(i,j), and then the spatial distribution of local hot spots and low-temperature regions can be identified through this matrix.

[0023] Furthermore, based on the charging and discharging history of the target lithium battery pack, the equivalent ampere-hour throughput of each deep charge-discharge cycle is accumulated. When the accumulated ampere-hour throughput reaches a preset cycle threshold, a cycle aging count is recorded. The preset cycle threshold is equivalent to the ampere-hour throughput of one standard cycle, and is taken as 70% to 90% of the rated capacity. For example, it can be taken as 80% of the rated capacity equivalent ampere-hour throughput. For example, for a battery pack with a rated capacity of 100 ampere-hours, a cycle aging count is recorded when the accumulated ampere-hour throughput reaches 80 ampere-hours.

[0024] S20: Based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics, calculate the instantaneous load rate, terminal voltage range, and temperature gradient vector; In this embodiment of the application, based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cyclic aging characteristics extracted in step S10, the instantaneous load rate, terminal voltage range and temperature gradient vector are calculated.

[0025] Specifically, step S20 in the method includes: The ratio of the current ratio characteristic to the voltage dispersion characteristic is filtered by a first-order low-pass filter and used as the instantaneous load rate. The difference between the maximum and minimum values ​​of the terminal voltages of all individual cells at the current moment is taken as the terminal voltage range. Spatial difference is performed on the highest and lowest temperatures in the temperature field distribution characteristics, and a temperature gradient vector is constructed by combining the physical arrangement of each individual cell.

[0026] In this embodiment, the ratio of current ratio characteristic to voltage dispersion characteristic is first used as the instantaneous load rate after being filtered by a first-order low-pass filter. Since it is necessary to filter out high-frequency noise in the load current and retain the load change trend, the cutoff frequency of the first-order low-pass filter is in the range of 1~10Hz, for example, it can be set to 5Hz, to filter out high-frequency noise components in the load current.

[0027] For example, the current ratio characteristic is 2C, the normalized voltage dispersion characteristic is 0.4, and the ratio of the two is 5. After filtering, the instantaneous load rate is stable at around 5. The larger this value is, the higher the current load intensity or the better the battery pack consistency.

[0028] Secondly, the difference between the maximum and minimum values ​​of the terminal voltage of all individual cells at the current moment is taken as the terminal voltage range. For example, when the battery pack contains 16 cells connected in series, if the highest terminal voltage is measured to be 3.78V and the lowest terminal voltage is 3.65V, then the terminal voltage range is 3.78-3.65=0.13V, or 130mV.

[0029] Next, spatial difference is performed on the highest and lowest temperatures in the temperature field distribution characteristics, and a temperature gradient vector is constructed by combining the physical arrangement of each individual cell. This vector is used to characterize the non-uniformity of the temperature distribution and the direction of heat conduction inside the battery pack. Specifically, the spatial difference can be used to calculate local gradient components based on the temperature difference and physical distance between adjacent individual cells, and then the overall temperature gradient vector is obtained through vector synthesis.

[0030] For example, for an M×K array of cells arranged in row-major order, let the temperature of cell (i,j) be T(i,j), the temperature of its right neighbor cell be T(i,j+1), and the temperature of its bottom neighbor cell be T(i+1,j). Then, the local gradient in the x-column direction is approximately [T(i,j+1)−T(i,j)] / Δx, and the local gradient in the y-row direction is approximately [T(i+1,j)−T(i,j)] / Δy, where Δx and Δy are the physical distances between the cell centers in the corresponding directions. By averaging all effective local gradients by position, a two-dimensional temperature gradient vector with direction and amplitude is finally constructed. This vector not only reflects the magnitude of the temperature difference but also indicates the trend of heat flow, providing a spatial basis for setting the pulse frequency based on the lowest temperature.

[0031] S30: When the instantaneous load rate exceeds a preset threshold, it is identified as a fast charging scenario or a high-rate discharge scenario. A reference pulse frequency is set according to the lowest temperature value in the temperature gradient vector, and the reference pulse frequency is aged and corrected according to the cumulative number of cycles to obtain a corrected pulse frequency. In this embodiment, when the instantaneous load rate exceeds a preset threshold, it is identified as a fast charging scenario or a high-rate discharge scenario. The preset threshold refers to the significant battery polarization that occurs when the rate exceeds this threshold, requiring active balancing to be initiated. The value range is 1.5C to 3C, for example, 2C. This means that when the instantaneous load rate is greater than 2C, it is determined to be a fast charging or high-rate discharge condition that requires active balancing to be initiated. The reference pulse frequency is set according to the lowest temperature value in the temperature gradient vector, and the cumulative number of cycles is extracted from the cumulative cycle aging characteristics. Based on this, aging correction is performed to obtain a correction pulse frequency suitable for the current battery state.

[0032] Specifically, step S30 in the method includes: Using the lowest temperature value as input, a preset temperature-frequency base mapping table is queried to obtain the base pulse frequency, wherein the temperature-frequency base mapping table sets a frequency decreasing slope in the low temperature range and a frequency increasing slope in the high temperature range. Obtain the current cumulative number of cycles, and based on the cycle life interval in which the cumulative number of cycles is located, linearly interpolate from the preset aging attenuation coefficient table to obtain the frequency aging attenuation coefficient; The corrected pulse frequency is obtained by multiplying the base pulse frequency by the frequency aging attenuation coefficient.

[0033] The cycle life interval includes at least an initial stage, a middle stage, and a final stage. The frequency aging attenuation coefficient is 1.0 in the initial stage, decreases with a first linear slope in the middle stage, and decreases with a second linear slope in the final stage, with the absolute value of the second linear slope being greater than the first linear slope.

[0034] In this embodiment of the application, firstly, the lowest temperature value is used as input to query a preset temperature-frequency baseline mapping table to obtain the baseline pulse frequency. The mapping table is set based on the following: In low-temperature environments, the risk of lithium plating at the negative electrode of lithium-ion batteries increases significantly. Lithium plating is closely related to low temperature, high current, and polarization effects. Therefore, a frequency drop slope is set in the low-temperature range—that is, the lower the temperature, the lower the pulse frequency—to prolong the conduction time of the switching transistor in each equalization cycle and reduce the peak value of the instantaneous equalization current, thereby reducing the risk of lithium plating. Specifically, the low-temperature range is defined as -20℃ to 10℃. Within this range, the frequency increases with increasing temperature at a drop slope of 5~20Hz / ℃, meaning that for every 1℃ increase in temperature, the frequency increases by 5~20Hz.

[0035] In high-temperature environments, the rate of chemical reactions inside the battery accelerates. Appropriately increasing the pulse frequency helps to improve the balancing efficiency. The high-temperature range is defined as 35℃ to 60℃. Within this range, the frequency increases with the temperature at a rising slope of 3~15Hz / ℃, that is, for every 1℃ increase in temperature, the frequency increases by 3~15Hz. The normal temperature range is 10℃ to 35℃, and the base frequency value is used without temperature correction.

[0036] Secondly, the current cumulative cycle count is obtained. Based on the cycle life range in which the cumulative cycle count falls, the frequency aging attenuation coefficient is obtained by linear interpolation from a preset aging attenuation coefficient table. The cycle life range is divided into an initial stage, a middle stage, and a final stage. For example, the initial stage is 0% to 40% of the rated cycle life, the middle stage is 40% to 75%, and the final stage is 75% to 100%. The frequency aging attenuation coefficient is 1.0 in the initial stage, decreases by a first linear slope in the middle stage, and decreases by a second linear slope in the final stage. The linear slope is set according to the degree of influence of battery aging on internal resistance growth and thermal stability. The first linear slope ranges from -0.001 to -0.003 / cycle%, and the second linear slope ranges from -0.004 to -0.008 / cycle%. For example, it decreases to 0.85 in the middle stage by the first linear slope and to 0.70 in the final stage by the second linear slope.

[0037] As the battery ages, its internal resistance increases and polarization intensifies. If the pulse frequency is not reduced, polarization accumulation will be aggravated, accelerating battery performance degradation. Therefore, the absolute value of the second linear slope is greater than that of the first linear slope. The base pulse frequency is multiplied by the frequency aging attenuation coefficient to obtain the corrected pulse frequency.

[0038] For example, if the current minimum temperature is 5℃, the base pulse frequency is 800Hz according to the temperature-frequency base mapping table. The cumulative number of cycles has reached 60% of the rated life, which is in the middle stage. The corresponding frequency aging attenuation coefficient is 0.92. Then the corrected pulse frequency is 800×0.92=736Hz. This frequency avoids the instantaneous large current impact caused by high frequency switching at low temperatures, and also takes into account the need for balanced and mild aging of the battery.

[0039] S40: Set the reference pulse duty cycle according to the instantaneous load rate, and dynamically correct the reference pulse duty cycle according to the terminal voltage range to obtain the corrected pulse duty cycle; In this embodiment, after correcting the basic pulse frequency based on the frequency aging attenuation coefficient, the reference pulse duty cycle is set according to the instantaneous load rate, and the duty cycle is dynamically adjusted in combination with the terminal voltage difference to achieve a balanced intensity that matches the degree of inconsistency of the current battery pack.

[0040] Specifically, step S40 in the method includes: The instantaneous load rate is matched with a preset load rate-duty cycle reference curve to obtain the reference pulse duty cycle; The terminal voltage range is compared with a preset imbalance threshold. When the terminal voltage range is less than the first imbalance threshold, the correction amount is zero. When the terminal voltage range is between the first imbalance threshold and the second imbalance threshold, the correction amount is a proportional increment. When the terminal voltage range is greater than the second imbalance threshold, the correction amount is the clamping upper limit value; The corrected pulse duty cycle is obtained by adding the reference pulse duty cycle to the correction amount.

[0041] In this embodiment, the instantaneous load rate is first matched with a preset load rate-duty cycle reference curve to obtain the reference pulse duty cycle. This reference curve is pre-calibrated based on the polarization characteristics and thermal response characteristics of the battery pack under different load intensities, and is usually non-linear. For example, in the low load rate range of less than 0.5C, the duty cycle is maintained at a low level, such as 10% to 20%, to avoid unnecessary energy loss. In the medium to high load rate range of 0.5C to 2C, the duty cycle increases approximately linearly with the load rate to compensate for the decrease in equalization efficiency caused by the increase in current. When the load rate exceeds 2C and enters the fast charging or high-rate discharge region, the duty cycle growth tends to be slow or even slightly decreases to prevent overheating of the switching devices and local overcurrent caused by the superposition of equalization current and main circuit current.

[0042] Secondly, the voltage difference between the terminals is compared with a preset imbalance threshold. The first imbalance threshold is defined as follows: when the difference is less than this value, no additional balancing effort is required, and the value range is 15~25mV. The second imbalance threshold is defined as follows: when the difference is greater than this value, full balancing effort is required, and the value range is 40~60mV. For example, in this application, the first imbalance threshold is set to 20mV and the second imbalance threshold is set to 50mV.

[0043] Furthermore, when the voltage range difference is less than 20mV, it indicates good consistency between individual cells, and there is no need to enhance the equalization strength; the correction amount is set to zero. When the range difference is between 20mV and 50mV, the correction amount increases dynamically in a proportional increment. For example, for every 1mV increase in range difference, the duty cycle correction amount increases by 0.5%, up to a maximum of 15%. When the range difference exceeds 50mV, it is judged as a severe imbalance state, and the correction amount reaches the clamping upper limit value to quickly suppress the voltage divergence trend. The duty cycle correction clamping upper limit does not exceed ±10% to prevent the duty cycle from exceeding the safe range; for example, 10% can be used.

[0044] Finally, the reference pulse duty cycle is added to the above correction amount to obtain the final corrected pulse duty cycle. This duty cycle is output after being limited. For example, if the current instantaneous load rate is 1.8C, the reference duty cycle is 35% according to the load rate-duty cycle reference curve, and the measured terminal voltage range is 35mV, which is in the range of 20mV~50mV, then the correction amount is (35−20)×0.5%=7.5%, and the final corrected pulse duty cycle is 35%+7.5%=42.5%. This strategy realizes the dual adaptive adjustment of the balancing intensity to the load condition and the battery inconsistency state, and improves the timeliness and accuracy of active balancing under the premise of ensuring safety.

[0045] S50: Control the equalization switch with the corrected pulse frequency and the corrected pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

[0046] In this embodiment, the corrected pulse frequency and corrected pulse duty cycle are used as control parameters to drive the switching transistors in the equalization circuit to turn on and off according to the set PWM waveform, thereby implementing directional energy transfer between target individual cells and realizing dynamic active equalization. PWM refers to pulse width modulation technology, which precisely controls the average value of the equalization current and the energy transfer rate without changing the power supply voltage by adjusting the on and off time ratio of the switching transistors.

[0047] Specifically, step S50 in the method includes: The correction pulse frequency and the correction pulse duty cycle are converted into a pulse width modulation control signal. During each cycle of the pulse width modulation control signal, the equalization switch is turned on during the high-level period and turned off during the low-level period. The voltage change rate of each cell during the equalization process is monitored in real time. When the voltage change rate of any cell exceeds the preset safety slope threshold, protective frequency reduction or duty cycle reduction operation is triggered. The current loop current data, the correction pulse frequency, the correction pulse duty cycle, and the voltage range feedback after execution are encapsulated into a control strategy data frame and output to the battery management system through the communication interface to update the current charge and discharge control strategy.

[0048] In this embodiment, the correction pulse frequency and correction pulse duty cycle are first converted into a standard PWM control signal. The period of this signal is determined by the reciprocal of the correction pulse frequency, and the high-level duration is determined by the product of the duty cycle and the period. This signal is used to precisely control the conduction time of the equalization switching transistors, such as MOSFETs or IGBTs. Within each PWM cycle, when the signal is high, the energy storage elements in the equalization circuit, such as inductors or capacitors, extract energy from the cells with high voltages. When the signal is low, energy transfer stops to avoid over-equalization or reverse current injection.

[0049] Secondly, during the equalization process, the voltage change rate of each individual cell is monitored in real time at a sampling rate of no less than 1kHz. If the absolute value of the voltage change rate of any cell exceeds the preset safe slope threshold, it is determined that there is a risk of local overcurrent, abnormal contact, or impending thermal runaway, and a protection mechanism is immediately triggered. For example, the current correction pulse frequency is reduced to 50%~70% of its original value, or the duty cycle is reduced, and then gradually restored in subsequent cycles until the voltage change rate returns to the normal range. Among these, exceeding the safe slope threshold may cause a voltage surge. The safe slope threshold ranges from 1 to 10mV / s, for example, 5mV / s can be used.

[0050] Finally, the current loop current data, including the main loop current and the equalization branch current, the corrected pulse frequency, the corrected pulse duty cycle, and the voltage range feedback after a complete equalization cycle are packaged and encapsulated into a structured control strategy data frame. The voltage range feedback refers to the difference between the maximum and minimum voltages after equalization. This data frame is output to the main control unit of the battery management system via the CAN bus or UART interface to update the charging and discharging power limits, SOC estimation correction, and health status assessment. It also serves as the input basis for the next round of equalization decisions, forming a closed-loop optimization control. The above process ensures the safety, responsiveness, and strategy traceability of the equalization operation under dynamic operating conditions.

[0051] Further, converting the corrected pulse frequency and the corrected pulse duty cycle into a pulse width modulation control signal includes: The corrected pulse frequency is used as the period reference of the pulse width modulation signal to calculate the period duration, and the high-level conduction duration and low-level turn-off duration are calculated according to the duty cycle of the corrected pulse. A symmetrical or asymmetrical pulse width modulation waveform is generated using the high-level on-time and the low-level off-time. In the fast charging scenario, an asymmetrical waveform is used, and in the high-rate discharge scenario, a symmetrical waveform is used. The pulse width modulation waveform is amplified by the driving circuit and applied to the control electrode of the equalization switch transistor, and the switching action of adjacent equalization channels is phase-shifted. At the start of each cycle of the pulse width modulation control signal, the instantaneous loop current and terminal voltage difference of the target lithium battery pack are synchronously acquired as feedback input for the adaptive adjustment of frequency and duty cycle in the next cycle.

[0052] In this embodiment, firstly, the corrected pulse frequency and the corrected pulse duty cycle are converted into actual pulse width modulation control signals to drive the equalization switch to perform active equalization operation. Specifically, the corrected pulse frequency is converted into the period reference of the PWM signal. The unit of the corrected pulse frequency is Hz, and its reciprocal is the period duration of the PWM signal, that is, the period duration = 1 / corrected pulse frequency. For example, if the corrected pulse frequency is 1000Hz, then the period duration = 1 / 1000 = 1 millisecond.

[0053] Secondly, the high-level conduction duration and low-level turn-off duration are calculated based on the corrected pulse duty cycle. The corrected pulse duty cycle is a percentage value. The calculation formulas for the high-level conduction duration and low-level turn-off duration are: high-level conduction duration = cycle duration × corrected pulse duty cycle, low-level turn-off duration = cycle duration × (1 - corrected pulse duty cycle).

[0054] For example, when the period is 1 millisecond and the correction pulse duty cycle is 60%, the high-level conduction time is 0.6 milliseconds and the low-level turn-off time is 0.4 milliseconds. The high-level period controls the equalization switch to be turned on, and the low-level period controls the equalization switch to be turned off, thereby achieving precise control of the equalization current.

[0055] Furthermore, symmetrical or asymmetrical pulse width modulation waveforms are generated using the high-level on-time and low-level off-time. A symmetrical waveform refers to a PWM signal whose high and low levels are symmetrically distributed relative to the midpoint of the cycle, meaning that the high-level on-time and low-level off-time each occupy a continuous period within half of the cycle. An asymmetrical waveform refers to a high-level on-time that is not centrally distributed within the cycle, for example, the high-level time is concentrated at the beginning or end of the cycle.

[0056] In this application, an asymmetrical waveform is used in fast charging scenarios, while a symmetrical waveform is used in high-rate discharging scenarios. Specifically, in fast charging scenarios, the battery pack is charged at a high rate current, and it is necessary to avoid generating a large current spike at the moment of switching action when the equalization switch is turned on. The asymmetrical waveform, by concentrating the high-level conduction period at the beginning of the PWM cycle, utilizes the inertial smoothing effect of inductor or capacitor components to effectively suppress the current surge at the moment of conduction, reducing the risk of lithium plating on the battery's negative electrode. At the same time, the asymmetrical waveform provides a longer inductor energy storage time at the start of conduction, which is beneficial to improving the energy transfer efficiency of the equalization system.

[0057] In high-rate discharge scenarios, the battery pack outputs a large current. When the equalization switch is turned on, it mainly undertakes the bypass shunting function. The symmetrical waveform makes the conduction period of the switch uniformly distributed within the cycle, avoiding the concentrated release of energy in a certain period of time, which would cause excessive local temperature rise. At the same time, the symmetrical waveform helps to reduce the electromagnetic interference generated by the switching action and maintain the stability of the discharge process.

[0058] Furthermore, the pulse width modulation waveform is amplified by the driver circuit and applied to the control electrode of the equalization switch. The switching actions of adjacent equalization channels are also phase-shifted. The PWM signal output from the controller is typically a 3.3V or 5V logic level, which cannot directly drive the power switch. In this application, the PWM signal is first amplified and current-enhanced by the driver circuit, converting the logic level to a voltage amplitude suitable for the gate drive of the equalization switch, such as a metal-oxide-semiconductor field-effect transistor or an insulated-gate bipolar transistor. A typical value is 12V to 15V, ensuring that the switch can be turned on and off quickly and reliably.

[0059] Specifically, when a battery pack contains multiple equalization channels, the simultaneous conduction of equalization switches in different channels can trigger circulating current surges between multiple individual cells, resulting in unnecessary energy loss and potential equipment safety hazards. In this application, the PWM signals of adjacent channels are phase-shifted, with a phase shift angle of 360° per channel.

[0060] For example, when the battery pack has 4 equalization channels, the phases of each channel are staggered by 90°, that is, the PWM signal phase of channel 1 is 0°, channel 2 is 90°, channel 3 is 180°, and channel 4 is 270°. Through phase staggering, the switching actions of multiple equalization channels are distributed in time, avoiding the impact of circulating current superposition caused by multiple channels being turned on at the same time, reducing the ripple current stress of the bus capacitor, and extending the life of the equalization network.

[0061] Finally, at the start of each cycle of the pulse width modulation control signal, the instantaneous loop current and terminal voltage difference of the target lithium battery pack are synchronously collected as feedback input for the adaptive adjustment of frequency and duty cycle in the next cycle. The rising edge at the start of each PWM cycle triggers a data acquisition operation, and the instantaneous loop current and terminal voltage difference at that moment are sampled and stored. The adaptive frequency adjustment and adaptive duty cycle adjustment in steps S40 and S50 are calculated based on the data collected at the start of the previous cycle. Therefore, the control parameters are updated once in each cycle to achieve real-time tracking of battery state changes.

[0062] This synchronous acquisition mechanism ensures the timing correspondence between feedback data and control parameters. That is, the balancing action performed in the current cycle is calculated based on the battery state at the end of the previous cycle, avoiding control lag or data misalignment problems that may occur with asynchronous sampling. For example, when the sampling period is 10 milliseconds, the control acquires the latest loop current and terminal voltage range every 10 milliseconds, and calculates the correction pulse frequency and correction pulse duty cycle for the next cycle accordingly, thereby achieving closed-loop adaptive adjustment.

[0063] In summary, compared to existing technologies, this application constructs an active balancing mechanism with dual-parameter coordinated control of frequency and duty cycle by integrating four-dimensional characteristics: current ratio, voltage dispersion, temperature field distribution, and cumulative cycle aging. This mechanism not only dynamically sets the benchmark control parameters based on instantaneous load intensity but also performs real-time corrections based on the degree of inconsistency and thermal state within the battery pack, achieving precise adaptation of the balancing strategy to complex operating conditions. Simultaneously, by introducing PWM waveform symmetry selection, multi-channel phase-shifting drive, and periodic synchronous feedback acquisition, it effectively suppresses switching transient impacts, circulating current interference, and control lag issues, significantly improving balancing efficiency and system robustness while ensuring safety boundaries.

[0064] In summary, the embodiments of this application have at least the following technical effects: This application provides a charging and discharging control method for lithium battery packs. First, by integrating multi-dimensional state characteristics such as current rate, voltage dispersion, temperature field distribution, and cumulative cycle aging, a dynamic evaluation system coupled with actual operating conditions is constructed. Second, after identifying high-load scenarios such as fast charging or high-rate discharging, the pulse frequency is set based on the lowest temperature value in the temperature gradient vector, and a frequency aging correction mechanism based on the cycle life range is introduced. Simultaneously, the duty cycle is dynamically corrected in a segmented manner through the terminal voltage range, achieving intelligent adjustment capabilities that maintain efficient operation under mild imbalance and enhance equalization intervention under severe imbalance. Furthermore, the generated pulse width modulation signal supports waveform symmetry switching and channel phase reversal control, which not only improves energy transfer efficiency but also effectively suppresses current spikes and electromagnetic interference caused by synchronous conduction of switching transistors. Finally, by real-time feedback of the individual cell voltage change rate and triggering protective frequency reduction or duty cycle reduction operations, the equalization efficiency and overall energy efficiency under high-rate charging and discharging scenarios are further improved while ensuring long-term reliable operation of the battery pack.

[0065] Through the above technical solution, this application effectively solves the contradiction between rigid balancing strategies, insufficient safety margin and energy efficiency loss in traditional lithium battery packs under complex operating conditions. Furthermore, by integrating a high-precision sensing unit and a controller with adaptive decision-making capabilities, the lithium battery pack can perceive the multidimensional heterogeneity of battery status in real time during operation.

[0066] Example 2, as Figure 2 As shown, based on the same inventive concept as the lithium battery pack charging and discharging control method provided in Embodiment 1, this application also provides a lithium battery pack charging and discharging control system, including: The data acquisition module 11 is used to extract current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cycle aging characteristics based on the loop current data of the target lithium battery pack, the terminal voltage and surface temperature of each individual cell. State calculation module 12 is used to calculate instantaneous load rate, terminal voltage range, and temperature gradient vector based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics. The frequency adaptive module 13 is used to identify a fast charging scenario or a high-rate discharge scenario when the instantaneous load rate exceeds a preset threshold, set a reference pulse frequency according to the lowest temperature value in the temperature gradient vector, and perform aging correction on the reference pulse frequency according to the cumulative number of cycles to obtain a corrected pulse frequency. The duty cycle adaptive module 14 is used to set the reference pulse duty cycle according to the instantaneous load rate, and to dynamically correct the reference pulse duty cycle according to the terminal voltage range to obtain the corrected pulse duty cycle. The strategy generation and output module 15 is used to control the equalization switch with the correction pulse frequency and the correction pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

[0067] In one embodiment, the data acquisition module 11 is specifically used for: The loop current data is sampled using a sliding window, and the ratio of the average current within the window to the rated current is calculated as the current ratio feature. The terminal voltages of all individual cells are sorted in real time, and the difference between the maximum and minimum terminal voltages is calculated as the instantaneous voltage range. The root mean square value of the range sequence within a preset time window is used as the voltage dispersion feature. Spatial interpolation is performed on the surface temperature of all individual cells to generate a temperature field matrix, and the highest temperature, lowest temperature and average temperature in the temperature field matrix are extracted to form the temperature field distribution characteristics. Based on the charge and discharge history of the target lithium battery pack, the equivalent ampere-hour throughput of each deep charge and discharge cycle is accumulated. When the accumulated ampere-hour throughput reaches a preset cycle threshold, a cycle aging count is recorded to obtain the accumulated cycle aging characteristics.

[0068] In one embodiment, the state calculation module 12 is specifically used for: The ratio of the current ratio characteristic to the voltage dispersion characteristic is filtered by a first-order low-pass filter and used as the instantaneous load rate. The difference between the maximum and minimum values ​​of the terminal voltages of all individual cells at the current moment is taken as the terminal voltage range. Spatial difference is performed on the highest and lowest temperatures in the temperature field distribution characteristics, and a temperature gradient vector is constructed by combining the physical arrangement of each individual cell.

[0069] In one embodiment, the frequency adaptive module 13 is specifically used for: Using the lowest temperature value as input, a preset temperature-frequency base mapping table is queried to obtain the base pulse frequency, wherein the temperature-frequency base mapping table sets a frequency decreasing slope in the low temperature range and a frequency increasing slope in the high temperature range. Obtain the current cumulative number of cycles, and based on the cycle life interval in which the cumulative number of cycles is located, linearly interpolate from the preset aging attenuation coefficient table to obtain the frequency aging attenuation coefficient; The corrected pulse frequency is obtained by multiplying the base pulse frequency by the frequency aging attenuation coefficient.

[0070] The cycle life interval includes at least an initial stage, a middle stage, and a final stage. The frequency aging attenuation coefficient is 1.0 in the initial stage, decreases with a first linear slope in the middle stage, and decreases with a second linear slope in the final stage, with the absolute value of the second linear slope being greater than the first linear slope.

[0071] Furthermore, in one embodiment, the duty cycle adaptive module 14 is specifically used for: The instantaneous load rate is matched with a preset load rate-duty cycle reference curve to obtain the reference pulse duty cycle; The terminal voltage range is compared with a preset imbalance threshold. When the terminal voltage range is less than the first imbalance threshold, the correction amount is zero. When the terminal voltage range is between the first imbalance threshold and the second imbalance threshold, the correction amount is a proportional increment. When the terminal voltage range is greater than the second imbalance threshold, the correction amount is the clamping upper limit value; The corrected pulse duty cycle is obtained by adding the reference pulse duty cycle to the correction amount.

[0072] In one embodiment, the policy generation and output module 15 is specifically used for: The correction pulse frequency and the correction pulse duty cycle are converted into a pulse width modulation control signal. During each cycle of the pulse width modulation control signal, the equalization switch is turned on during the high-level period and turned off during the low-level period. The voltage change rate of each cell during the equalization process is monitored in real time. When the voltage change rate of any cell exceeds the preset safety slope threshold, protective frequency reduction or duty cycle reduction operation is triggered. The current loop current data, the correction pulse frequency, the correction pulse duty cycle, and the voltage range feedback after execution are encapsulated into a control strategy data frame and output to the battery management system through the communication interface to update the current charge and discharge control strategy.

[0073] Further, in one embodiment, converting the corrected pulse frequency and the corrected pulse duty cycle into a pulse width modulation control signal includes: The corrected pulse frequency is used as the period reference of the pulse width modulation signal to calculate the period duration, and the high-level conduction duration and low-level turn-off duration are calculated according to the duty cycle of the corrected pulse. A symmetrical or asymmetrical pulse width modulation waveform is generated using the high-level on-time and the low-level off-time. In the fast charging scenario, an asymmetrical waveform is used, and in the high-rate discharge scenario, a symmetrical waveform is used. The pulse width modulation waveform is amplified by the driving circuit and applied to the control electrode of the equalization switch transistor, and the switching action of adjacent equalization channels is phase-shifted. At the start of each cycle of the pulse width modulation control signal, the instantaneous loop current and terminal voltage difference of the target lithium battery pack are synchronously acquired as feedback input for the adaptive adjustment of frequency and duty cycle in the next cycle.

[0074] Example 3: This embodiment of the invention also provides a lithium battery pack, comprising: The battery pack itself is composed of multiple individual cells connected in series or parallel. The equalization switch network, connected between individual cells, is used to perform active equalization during charging and discharging. A temperature sensing array is attached to the surface of each individual battery cell to collect surface temperature in real time. The current sensing unit is connected in series in the main circuit of the battery pack to collect circuit current data; A voltage sampling unit is connected in parallel across each individual cell to collect the voltage at each cell terminal. The controller 600 is connected to the equalization switch network, the temperature sensor array, the current sensor unit, and the voltage sampling unit, respectively, as follows: Figure 3 As shown, the controller includes a memory 610 and a processor 620. The memory stores a computer program 611, and the processor is used to read and execute the computer program to implement the lithium battery pack charging and discharging control method of Embodiment 1.

Claims

1. A method for controlling the charging and discharging of a lithium battery pack, characterized in that, The method includes: Based on the loop current data of the target lithium battery pack, the terminal voltage and surface temperature of each individual cell, the current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics and cumulative cycle aging characteristics are extracted respectively. Based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics, the instantaneous load rate, terminal voltage range, and temperature gradient vector are calculated. When the instantaneous load rate exceeds a preset threshold, it is identified as a fast charging scenario or a high-rate discharge scenario. A reference pulse frequency is set according to the lowest temperature value in the temperature gradient vector, and the reference pulse frequency is aged and corrected according to the cumulative number of cycles to obtain a corrected pulse frequency. The reference pulse duty cycle is set according to the instantaneous load rate, and the reference pulse duty cycle is dynamically corrected according to the terminal voltage range to obtain the corrected pulse duty cycle. The equalization switch is controlled by the corrected pulse frequency and the corrected pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

2. The charging and discharging control method for a lithium battery pack according to claim 1, characterized in that, Based on the loop current data of the target lithium battery pack, the terminal voltage and surface temperature of each individual cell, current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cycle aging characteristics are extracted, including: The loop current data is sampled using a sliding window, and the ratio of the average current within the window to the rated current is calculated as the current ratio feature. The terminal voltages of all individual cells are sorted in real time, and the difference between the maximum and minimum terminal voltages is calculated as the instantaneous voltage range. The root mean square value of the range sequence within a preset time window is used as the voltage dispersion feature. Spatial interpolation is performed on the surface temperature of all individual cells to generate a temperature field matrix, and the highest temperature, lowest temperature and average temperature in the temperature field matrix are extracted to form the temperature field distribution characteristics. Based on the charge and discharge history of the target lithium battery pack, the equivalent ampere-hour throughput of each deep charge and discharge cycle is accumulated. When the accumulated ampere-hour throughput reaches a preset cycle threshold, a cycle aging count is recorded to obtain the accumulated cycle aging characteristics.

3. The charging and discharging control method for a lithium battery pack according to claim 1, characterized in that, Calculate the instantaneous load factor, terminal voltage range, and temperature gradient vector, including: The ratio of the current ratio characteristic to the voltage dispersion characteristic is filtered by a first-order low-pass filter and used as the instantaneous load rate. The difference between the maximum and minimum values ​​of the terminal voltages of all individual cells at the current moment is taken as the terminal voltage range. Spatial difference is performed on the highest and lowest temperatures in the temperature field distribution characteristics, and a temperature gradient vector is constructed by combining the physical arrangement of each individual cell.

4. The charging and discharging control method for a lithium battery pack according to claim 1, characterized in that, A reference pulse frequency is set based on the lowest temperature value in the temperature gradient vector, and the reference pulse frequency is aged and corrected based on the cumulative number of cycles to obtain a corrected pulse frequency, including: Using the lowest temperature value as input, a preset temperature-frequency base mapping table is queried to obtain the base pulse frequency, wherein the temperature-frequency base mapping table sets a frequency decreasing slope in the low temperature range and a frequency increasing slope in the high temperature range. Obtain the current cumulative number of cycles, and based on the cycle life interval in which the cumulative number of cycles is located, linearly interpolate from the preset aging attenuation coefficient table to obtain the frequency aging attenuation coefficient; The corrected pulse frequency is obtained by multiplying the base pulse frequency by the frequency aging attenuation coefficient.

5. The charging and discharging control method for a lithium battery pack according to claim 4, characterized in that, The cycle life range includes at least an initial stage, a middle stage, and a final stage. The frequency aging attenuation coefficient is 1.0 in the initial stage, decreases with a first linear slope in the middle stage, and decreases with a second linear slope in the final stage, with the absolute value of the second linear slope being greater than the first linear slope.

6. The charging and discharging control method for a lithium battery pack according to claim 1, characterized in that, The reference pulse duty cycle is set according to the instantaneous load rate, and the reference pulse duty cycle is dynamically corrected according to the terminal voltage range to obtain the corrected pulse duty cycle, including: The instantaneous load rate is matched with a preset load rate-duty cycle reference curve to obtain the reference pulse duty cycle; The terminal voltage range is compared with a preset imbalance threshold. When the terminal voltage range is less than the first imbalance threshold, the correction amount is zero. When the terminal voltage range is between the first imbalance threshold and the second imbalance threshold, the correction amount is a proportional increment. When the terminal voltage range is greater than the second imbalance threshold, the correction amount is the clamping upper limit value; The corrected pulse duty cycle is obtained by adding the reference pulse duty cycle to the correction amount.

7. The charging and discharging control method for a lithium battery pack according to claim 1, characterized in that, The charging and discharging circuit is actively balanced using the corrected pulse frequency and the corrected pulse duty cycle to generate and output the current charging and discharging control strategy for the lithium battery pack, including: The correction pulse frequency and the correction pulse duty cycle are converted into a pulse width modulation control signal. During each cycle of the pulse width modulation control signal, the equalization switch is turned on during the high-level period and turned off during the low-level period. The voltage change rate of each cell during the equalization process is monitored in real time. When the voltage change rate of any cell exceeds the preset safety slope threshold, protective frequency reduction or duty cycle reduction operation is triggered. The current loop current data, the correction pulse frequency, the correction pulse duty cycle, and the voltage range feedback after execution are encapsulated into a control strategy data frame and output to the battery management system through the communication interface to update the current charge and discharge control strategy.

8. The charging and discharging control method for a lithium battery pack according to claim 7, characterized in that, Converting the corrected pulse frequency and the corrected pulse duty cycle into a pulse width modulation control signal includes: The corrected pulse frequency is used as the period reference of the pulse width modulation signal to calculate the period duration, and the high-level conduction duration and low-level turn-off duration are calculated according to the duty cycle of the corrected pulse. A symmetrical or asymmetrical pulse width modulation waveform is generated using the high-level on-time and the low-level off-time. In the fast charging scenario, an asymmetrical waveform is used, and in the high-rate discharge scenario, a symmetrical waveform is used. The pulse width modulation waveform is amplified by the driving circuit and applied to the control electrode of the equalization switch transistor, and the switching action of adjacent equalization channels is phase-shifted. At the start of each cycle of the pulse width modulation control signal, the instantaneous loop current and terminal voltage difference of the target lithium battery pack are synchronously acquired as feedback input for the adaptive adjustment of frequency and duty cycle in the next cycle.

9. A charging and discharging control system for a lithium battery pack, characterized in that, A method for controlling the charging and discharging of a lithium battery pack according to any one of claims 1 to 8 includes: The data acquisition module is used to extract current rate characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cycle aging characteristics based on the loop current data of the target lithium battery pack, the terminal voltage of each individual cell, and the surface temperature. The state calculation module is used to calculate the instantaneous load rate, terminal voltage range, and temperature gradient vector based on the current ratio characteristics, voltage dispersion characteristics, temperature field distribution characteristics, and cumulative cyclic aging characteristics. The frequency adaptive module is used to identify a fast charging scenario or a high-rate discharge scenario when the instantaneous load rate exceeds a preset threshold, set a reference pulse frequency according to the lowest temperature value in the temperature gradient vector, and perform aging correction on the reference pulse frequency according to the cumulative number of cycles to obtain a corrected pulse frequency. The duty cycle adaptive module is used to set the reference pulse duty cycle according to the instantaneous load rate, and to dynamically correct the reference pulse duty cycle according to the terminal voltage range to obtain the corrected pulse duty cycle. The strategy generation and output module is used to control the equalization switch with the correction pulse frequency and the correction pulse duty cycle to generate and output the current charge and discharge control strategy of the lithium battery pack.

10. A lithium battery pack, characterized in that, include: The battery pack itself is composed of multiple individual cells connected in series or parallel. The equalization switch network, connected between individual cells, is used to perform active equalization during charging and discharging. A temperature sensing array is attached to the surface of each individual battery cell to collect surface temperature in real time. The current sensing unit is connected in series in the main circuit of the battery pack to collect circuit current data; A voltage sampling unit is connected in parallel across each individual cell to collect the voltage at each cell terminal. The controller is connected to the equalization switch network, the temperature sensing array, the current sensing unit, and the voltage sampling unit, respectively. The controller includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it implements the lithium battery pack charging and discharging control method as described in any one of claims 1 to 8.

Images