A heat management method, medium and device of an air-cooled energy storage system

Abstract

The application discloses a heat management method of an air-cooled energy storage system, a medium and equipment; the method comprises the following steps: collecting the battery core temperature of each battery pack in the energy storage system and calculating a temperature rise rate value and a temperature rise degree value based on a preset temperature rise reference value; weighting the temperature rise rate value and the temperature rise degree value to obtain a basic PWM value for controlling the air-cooled fan; calculating the battery core temperature difference of the whole energy storage system and the system average temperature, and when the calculated battery core temperature difference is greater than or equal to a preset temperature difference threshold, differentially compensating the basic PWM value according to the degree of the battery core temperature of each battery pack deviating from the system average temperature. The medium and equipment are used for implementing the above method. The application has the beneficial effects that: by introducing the temperature rise rate value representing the dynamic change trend of the battery core temperature, the rotating speed of the air-cooled fan corresponding to each battery pack can be dynamically adjusted according to the change of the temperature rise rate value, so that the temperature difference between different battery packs is effectively reduced while invalid heat dissipation is avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a thermal management method, medium and equipment for an air-cooled energy storage system. Background Technology

[0002] Energy storage products contain a large number of lithium-ion batteries. The performance and lifespan of lithium-ion batteries are quite sensitive to temperature, requiring careful temperature control. On the one hand, the temperature of the cells should not exceed the upper limit of the operating temperature or fall below the lower limit of the operating temperature to maintain good charge and discharge performance. On the other hand, the temperature difference between different cells in an energy storage system should be kept small to ensure good consistency and avoid the "weakest link" effect, where some cells perform significantly better or worse than the average level, thus dragging down the overall performance of the energy storage system.

[0003] To achieve temperature control, a thermal management module is configured within the energy storage system. This module can be understood as a three-layer implementation. The first layer is the information acquisition layer, which includes NTC temperature probes to collect cell temperature and ambient temperature, and current and voltage sensors to collect cell operating status. The second layer is the strategy layer, which develops thermal management strategies based on product characteristics. The strategy input information is the information collected in the first layer, and the output information is the action commands that guide the devices in the third execution layer, usually converted into programs and written in the control board. The third layer is the action execution layer, which consists of command execution devices, including fans, air conditioners, liquid cooling units, heating films, heaters, etc.

[0004] For the second layer of the thermal management module, existing technologies mainly control the start / stop and speed of the air-cooled fan based on the cell temperature. Specifically, when the cell temperature exceeds a set threshold, the air-cooled fan starts and performs differential speed control based on the average cell temperature of each battery pack; the battery pack with the highest average temperature corresponds to 100% speed, the battery pack with the lowest average temperature corresponds to 60% speed, and the air-cooled fan speed for battery packs with average temperatures in between is adjusted linearly. However, existing technologies have the following technical shortcomings in thermal management: (1) For the temperature rise control of the battery cell, the real-time temperature of the battery cell is considered only, without considering the temperature change trend. For example, different battery packs are located in different spaces. If the ventilation of battery pack A is good, while battery pack B is placed in a corner or exposed to direct sunlight, in the above scheme, battery pack B will still have a faster temperature rise.

[0005] (2) The differential speed strategy only considers the average temperature and does not consider the maximum and minimum temperatures. For example, if a corner of a well-ventilated battery pack is exposed to direct sunlight at a certain moment, the battery pack may have a lower average temperature but a higher maximum temperature. According to the existing technical solution, the battery pack will be given the lowest speed, which is not conducive to the control of the temperature difference of the overall system.

[0006] (3) The air intake temperature linkage was not considered, and the strategy of increasing the air volume corresponding to the higher temperature of the battery pack was adopted. This logic is effective when the air intake temperature is lower than the minimum temperature of the cells in the battery pack, but when the air intake temperature is higher than the cell temperature, turning on the fan is not conducive to heat dissipation of the cells and will also have a reverse effect on the temperature difference.

[0007] (4) No linkage of cell status, only cell temperature is concerned, not whether the cell is at rest or continuously charging and discharging and generating heat. The power increase of the air-cooled fan is cubically related to the speed increase; without considering the cell status, if the air-cooled fan speed is still fully increased when the battery pack is at rest and the heat dissipation requirement is very small, it will cause a large waste of energy. Summary of the Invention

[0008] One objective of this application is to provide a thermal management method for an air-cooled energy storage system that can solve at least one of the defects in the aforementioned background technology.

[0009] Another object of this application is to provide a computer-readable storage medium capable of implementing a thermal management method for an air-cooled energy storage system that addresses at least one of the deficiencies in the aforementioned background art.

[0010] Another object of this application is to provide an electronic device capable of implementing a thermal management method for an air-cooled energy storage system that solves at least one of the defects in the above-mentioned background art.

[0011] To achieve at least one of the above objectives, one aspect of this application provides a thermal management method for an air-cooled energy storage system, comprising the following steps: collecting the cell temperatures of each battery pack in the energy storage system, including the highest cell temperature, the lowest cell temperature, and the average cell temperature; calculating the temperature rise rate value and the temperature rise degree value relative to a preset target temperature based on the cell temperatures of each battery pack; performing a comprehensive calculation on the obtained temperature rise rate value and temperature rise degree value to obtain a basic PWM value for controlling the speed of the air-cooled fan corresponding to each battery pack; wherein the comprehensive calculation method for the temperature rise rate value and temperature rise degree value includes a linear weighted summation method, a multiplicative modulation method, and a PID control method; when calculating the basic PWM value, adaptively selecting the corresponding comprehensive calculation method based on different operating modes of the air-cooled fan; calculating the overall cell temperature difference and the system average temperature of the energy storage system; when the calculated cell temperature difference is greater than or equal to a preset temperature difference threshold, performing differential compensation on the basic PWM value according to the degree to which the cell temperature of each battery pack deviates from the system average temperature.

[0012] Preferably, when the temperature rise rate is greater than the first threshold and the temperature rise intensity is greater than the second threshold, it is determined that the air-cooled fan corresponding to the battery pack should operate in emergency cooling mode. In this case, the basic PWM value is obtained by comprehensively calculating the temperature rise rate and temperature rise intensity using a multiplicative modulation method. When the temperature rise rate is less than the third threshold and the temperature rise intensity is less than the fourth threshold, it is determined that the air-cooled fan corresponding to the battery pack should operate in energy-saving maintenance mode. In this case, the basic PWM value is obtained by comprehensively calculating the temperature rise rate and temperature rise intensity using a linear weighted summation method. When the temperature rise rate is between the first and third thresholds and the temperature rise intensity is between the second and fourth thresholds, it is determined that the air-cooled fan corresponding to the battery pack should operate in precise control mode. In this case, the basic PWM value is obtained by comprehensively calculating the temperature rise rate and temperature rise intensity using a PID control method. Wherein, the third threshold is less than the first threshold and the fourth threshold is less than the second threshold.

[0013] Preferably, the specific process for differential compensation of the base PWM value is as follows: determine whether there is a battery pack with the highest cell temperature in the energy storage system corresponding to a battery pack with the lowest average cell temperature, or a battery pack with the lowest cell temperature in the energy storage system corresponding to a battery pack with the highest average cell temperature; if so, keep the base PWM value corresponding to each battery pack unchanged and issue an abnormal temperature characteristic warning; if not, calculate the deviation between the cell temperature of each battery pack and the average temperature of the system, and use the absolute value of the maximum deviation as the compensation benchmark to compensate the base PWM value corresponding to each battery pack.

[0014] Preferably, the formula for calculating the compensation amount for compensating the base PWM value is: K×(TT) m-avg K / T0; where K represents the preset proportional value, T represents the cell temperature of the battery pack, and T m-avg T0 represents the average system temperature, and T0 represents the compensation baseline.

[0015] Preferably, the median of the average cell temperature of all battery packs is used as the system average temperature; the median temperature of the desired cell in the battery pack is used as the cell average temperature; and the compensation benchmark is calculated based on the deviation between the average cell temperature of each battery pack and the system average temperature.

[0016] Preferably, the intake air temperature and cell charging / discharging status of each battery pack in the energy storage system are collected; when the cell temperature difference in the energy storage system is less than the preset temperature difference threshold, or after the differential compensation of the basic PWM value is completed, the lowest intake air temperature and the highest cell temperature in the energy storage system are compared; if the highest cell temperature is less than or equal to the lowest intake air temperature, the basic PWM value corresponding to all battery packs is set to zero; otherwise, the basic PWM value corresponding to each battery pack is subject to upper and lower limit constraints and range projection based on the cell charging / discharging status.

[0017] Preferably, when the highest cell temperature is greater than the lowest air intake temperature, if the base PWM value corresponding to the battery pack is less than 50%, it is set to zero; otherwise, the base PWM value corresponding to each battery pack is subject to upper and lower limit constraints and range projection based on the cell charging and discharging status.

[0018] Preferably, the cell charging and discharging states include a static state and a charging and discharging state; the specific process of constraining the upper and lower limits and projecting the range of the basic PWM value is as follows: set the lower limit of the PWM value as a, the upper limit of the PWM value of the cell in the static state as b, and the upper limit of the PWM value of the cell in the charging and discharging state as c; where a < b < c ≤ 100%; when the cells of the battery pack are in the charging and discharging state, the corresponding basic PWM value is projected proportionally to the range [a, c]; when the cells of the battery pack are in the static state, the corresponding basic PWM value is projected proportionally to the range [a, b].

[0019] Another aspect of this application provides a computer-readable storage medium storing a computer program; when the computer program is executed by a processor, it implements the above-described thermal management method for an air-cooled energy storage system.

[0020] Another aspect of this application provides an electronic device, including a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the above-described thermal management method for an air-cooled energy storage system.

[0021] Compared with the prior art, the beneficial effects of this application are as follows: This application introduces a temperature rise rate value, which characterizes the dynamic change trend of cell temperature, when calculating the basic PWM value. This allows the speed of the air-cooled fan corresponding to each battery pack to be dynamically adjusted according to the change of the temperature rise rate value. While avoiding ineffective heat dissipation, it can effectively reduce the temperature difference between different battery packs in the energy storage system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the working steps of this application; Figure 2 This is a schematic diagram illustrating the specific workflow of this application. Detailed Implementation

[0023] The present application will now be further described in conjunction with specific embodiments. It should be noted that, in the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0024] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0025] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0029] One aspect of this application provides a thermal management method for an air-cooled energy storage system, such as... Figure 1 and Figure 2 As shown, one preferred embodiment includes the following steps: collecting the cell temperatures of each battery pack in the energy storage system, including the highest cell temperature, the lowest cell temperature, and the average cell temperature; calculating the temperature rise rate and the degree of temperature rise relative to the target temperature based on the cell temperatures of each battery pack; performing a comprehensive calculation on the obtained temperature rise rate and degree of temperature rise values ​​to obtain the basic PWM values ​​for controlling the speed of the air-cooled fans corresponding to each battery pack; calculating the overall cell temperature difference and the system average temperature of the energy storage system; and when the calculated cell temperature difference is greater than or equal to a preset temperature difference threshold, performing differential compensation on the basic PWM values ​​based on the degree to which the cell temperatures of each battery pack deviate from the system average temperature.

[0030] Understandably, the temperature rise rate can characterize the dynamic trend of cell temperature change. In existing technologies, the air-cooling fan is controlled solely based on the current temperature of the battery pack, ignoring the temperature change trend. When the battery pack heats up rapidly due to poor placement or external heat sources, relying solely on the current temperature will prevent the corresponding air-cooling fan from responding in time, causing the battery pack temperature to continue to rise. This leads to a widening of the system temperature difference and affects the operational stability of the energy storage system.

[0031] In this embodiment, a temperature rise rate value, which characterizes the dynamic change trend of cell temperature, is introduced when calculating the basic PWM value. This allows the speed of the air-cooled fan corresponding to each battery pack to be dynamically adjusted according to the change of the temperature rise rate value. While avoiding ineffective heat dissipation, this can effectively reduce the temperature difference between different battery packs in the energy storage system, effectively suppress the temperature difference of the system, and ensure the working stability of the energy storage system.

[0032] In one specific embodiment, the cell temperature of each battery pack in the energy storage system can be detected by NTC temperature sensors arranged on the surface of multiple cells within each battery pack, and each cell is equipped with at least one temperature sampling point. Based on the above temperature detection configuration, the highest cell temperature refers to the maximum temperature obtained from all temperature sampling points within the battery pack, and the lowest cell temperature refers to the minimum temperature obtained from all temperature sampling points within the battery pack. For the average cell temperature, the average temperature obtained from all temperature sampling points within the battery pack can be used. However, considering that the detected temperatures at each temperature sampling point within the battery pack may have a large gradient, in this embodiment, the median temperature obtained from the corresponding temperature sampling points of all cells within the battery pack is preferably used for the average cell temperature.

[0033] In one specific embodiment, to obtain the temperature rise value used for calculating the basic PWM value, a target temperature T can be set first. set This target temperature can be considered the optimal temperature for the battery cell under ideal operating conditions. The specific selection of the target temperature can be based on the cell type and the actual usage scenario; for example, it could be 20℃, 25℃, or 30℃. After obtaining the target temperature, the current cell temperature T of the battery pack can be compared with the target temperature T. set Calculation of the degree of deviation between the two values ​​of temperature rise (TT) set The temperature rise rate value used for calculating the basic PWM value can be obtained by directly integrating the current cell temperature T of the battery pack over time t, i.e., the temperature rise rate value is dT / dt.

[0034] It should be noted that the cell temperature T includes the highest cell temperature T0. n-max Minimum cell temperature T n-min and the average temperature of the battery cell T n-avg When calculating the degree and rate of temperature rise, any temperature parameter in the cell temperature T can be selected. However, considering the highest cell temperature T... n-max It can characterize the most extreme operating conditions of the battery pack, while the average cell temperature T n-avg This can characterize the general operating conditions of the battery pack; therefore, in calculating the temperature level and temperature rise rate values ​​in this embodiment, the highest cell temperature T is preferably used. n-max Or the average temperature of the battery cell T n-avg .

[0035] In one specific embodiment, the comprehensive calculation methods for the temperature rise rate value and temperature rise degree value include linear weighted summation, multiplicative modulation, and PID control; for ease of understanding, the specific expressions of the basic PWM value under different comprehensive calculation methods will be described below.

[0036] Under the linear weighted summation method, the specific expression for the basic PWM value PWM0 is: PWM0=k1×(TT set )+ k2×(dT / dt).

[0037] In the formula, k1 and k2 both represent the corresponding calculation proportional coefficients, which are used to adjust the influence of the temperature rise degree value and the temperature rise rate value on the basic PWM value, respectively. The specific values ​​can be determined by the person skilled in the art according to their actual needs. For example, k1 can be 0.07~0.08 and k2 can be 0.1~0.3.

[0038] It is important to note that by setting the values ​​and units of the proportionality coefficients k1 and k2, it can be ensured that k1×(TT) set Since both k2×(dT / dt) are dimensionless terms, the normalized base PWM value can be obtained. Similarly, the coefficients in other subsequent calculation methods can also ensure that the normalized dimensionless base PWM value is obtained.

[0039] In multiplication modulation mode, the specific expression for the basic PWM value PWM0 is: PWM0=α×(TT set )×[1+β(dT / dt)].

[0040] In the formula, α represents the gain coefficient, which is used to adjust the influence of the temperature rise rate on the basic PWM value. The specific value can be calibrated experimentally, and the general range is 0.5~2. β represents the modulation coefficient, which is used to adjust the modulation depth of the temperature rise rate on the basic PWM value. The larger the value, the more significant the influence of the temperature rise rate on the basic PWM value. The specific range can be determined by those skilled in the art based on their actual needs, for example, it can be 0.1~2.

[0041] Under PID control, the specific expression for the basic PWM value PWM0 is: PWM0=K p ×(TT set ) +K i ×∫(TT set )dt+K d ×(dT / dt).

[0042] In the formula, Kp K represents the proportionality coefficient, used to amplify the intensity of the temperature rise; i K represents the integral coefficient, used to amplify the cumulative effect of historical temperature rise values; d These represent differential coefficients, used to amplify the effect of the temperature rise rate. The specific values ​​of these three factors can be determined by those skilled in the art based on their actual needs.

[0043] It's important to understand that during the actual operation of an energy storage system, the operating modes of the air-cooled fans corresponding to the battery pack can be categorized into three types based on the specific values ​​of the temperature rise rate and the degree of temperature rise: energy-saving maintenance mode, emergency cooling mode, and precise control mode. The energy-saving maintenance mode is primarily for scenarios where the battery pack's thermal load is low and complex control is not required; the emergency cooling mode is primarily for scenarios where the battery pack's temperature rise rate is high and thermal runaway is imminent, requiring maximum heat dissipation; and the precise control mode is primarily for scenarios where the battery pack's temperature needs fine-tuning. For ease of understanding, a specific example will be used below to describe in detail the specific classification of the operating modes of the air-cooled fans corresponding to the battery pack.

[0044] In a specific example, when the rate of temperature rise (dT / dt) is greater than the first threshold, and the degree of temperature rise (TT) set When the temperature rise rate (dT / dt) is greater than the second threshold, it can be determined that the battery pack is in a scenario where the temperature rise rate is high and thermal runaway is imminent, requiring maximum heat dissipation. In this case, the corresponding air-cooled fan should operate in emergency cooling mode. When the temperature rise rate (dT / dt) is less than the third threshold, and the temperature rise degree (TT) is... set When the temperature rise rate (dT / dt) is less than the fourth threshold, it can be determined that the battery pack is in a scenario with low heat load and no need for complex control. In this case, the corresponding air-cooled fan of the battery pack should operate in energy-saving mode. The third threshold is less than the first threshold, and the fourth threshold is less than the second threshold. When the temperature rise rate (dT / dt) is between the first and third thresholds, and the temperature rise degree (TT)... set When the value is between the second and fourth thresholds, it can be determined that the battery pack is in a scenario that requires fine adjustment, that is, the air-cooled fan corresponding to the battery pack should work in the precise control mode.

[0045] It should be understood that the specific values ​​of the first threshold, the second threshold, the third threshold and the fourth threshold can be determined by those skilled in the art according to their actual needs; for example, the first threshold can be 2~4℃ / min, the second threshold can be 0.2~0.3, the third threshold can be 0.3~1℃ / min and the fourth threshold can be 0.05~0.1.

[0046] It is understandable that, based on the above analysis, using a single comprehensive calculation method when calculating the basic PWM value may result in a value that does not conform to the current scenario. Therefore, in this embodiment, different methods can be used to calculate the basic PWM value for different operating scenarios of the battery pack. Specifically, when calculating the basic PWM value corresponding to the battery pack in energy-saving maintenance mode, a linear weighted summation method is used to comprehensively calculate the temperature rise rate and temperature rise level. When calculating the basic PWM value corresponding to the battery pack in emergency cooling mode, a multiplicative modulation method is used to comprehensively calculate the temperature rise rate and temperature rise level. When calculating the basic PWM value corresponding to the battery pack in precise control mode, a PID control method is used to comprehensively calculate the temperature rise rate and temperature rise level.

[0047] In one specific embodiment, the cell temperature difference ΔT of the energy storage system is the highest cell temperature T corresponding to all battery packs. max With the lowest cell temperature T min The difference, i.e., the highest cell temperature T corresponding to all battery packs. n-max The maximum value is related to the lowest cell temperature T corresponding to all battery packs. n-min The difference between the minimum and maximum values. When the cell temperature difference ΔT in the energy storage system ≥ T th (T) th When the preset temperature difference threshold (which can be 2~10℃) is reached, it indicates that the temperature consistency of each battery pack in the energy storage system is poor. Differential speed control of the air-cooled fans corresponding to each battery pack is required. Therefore, differential speed compensation is needed for the basic PWM value corresponding to each battery pack. The specific process is as follows: determine whether there is a battery pack with the highest cell temperature in the energy storage system corresponding to the battery pack with the lowest average cell temperature, or vice versa. If so, maintain the basic PWM value corresponding to each battery pack and issue a temperature anomaly warning. If not, calculate the deviation between the cell temperature of each battery pack and the system average temperature, and use the absolute value of the maximum deviation as the compensation benchmark to compensate the basic PWM value corresponding to each battery pack.

[0048] It should be understood that since the basic PWM values ​​of different battery packs have been calculated based on their respective temperature rise rate and temperature rise degree, the purpose of differential compensation is not to overturn the original allocation, but to further enhance the speed adjustment of the air-cooled fan corresponding to the battery pack whose cell temperature deviates from the system average level when the temperature difference is already large; that is, the greater the deviation, the greater the compensation magnitude, thereby prompting the temperature of each battery pack to converge to the system average level.

[0049] It is understandable that, such as Figure 2As shown, when performing differential compensation on the base PWM value, all battery packs in the energy storage system can be sorted. The preferred sorting method is based on the average cell temperature. In a specific example, assuming the energy storage system includes N battery packs, the sorted battery packs can be labeled as Pack#1 to Pack#N. Here, the highest cell temperature T in the energy storage system can be set as... max The corresponding battery pack serial number is Pack#A, and the lowest cell temperature T in the energy storage system is... min The corresponding battery pack serial number is Pack#B. For the lowest average cell temperature T in the energy storage system... avg-min The corresponding battery pack, which is the average temperature T of all cells in the energy storage system. n-avg The battery pack corresponding to the minimum value can be labeled with Pack#C; for the highest average cell temperature T in the energy storage system avg-max The corresponding battery pack, which is the average temperature T of all cells in the energy storage system. n-avg The battery pack corresponding to the maximum value can be marked with the serial number Pack#D.

[0050] It's important to know that if Pack#A and Pack#C belong to the same battery pack, it indicates an abnormal situation of extremely uneven temperature distribution within the pack. This means that one or a few cells are at extremely high temperatures, while the rest are at relatively low temperatures, resulting in the pack having the lowest average cell temperature. Similarly, if Pack#B and Pack#D belong to the same battery pack, it also indicates an abnormal situation of extremely uneven temperature distribution within the pack.

[0051] The aforementioned anomalies may occur due to an internal short circuit in a cell within the battery pack, a loose connector causing excessive local resistance, or blockage of the internal airflow channels. In such abnormal conditions, forcibly applying differential speed compensation based on the deviation from the system average temperature might incorrectly allocate the air-cooled fan speed to normal battery packs with significantly different temperatures, neglecting the abnormal cells that genuinely require increased cooling, and potentially worsening the situation. Therefore, in this embodiment, once the aforementioned anomaly is detected, the base PWM value corresponding to each battery pack is immediately kept unchanged, i.e., no differential speed compensation is performed. Simultaneously, a temperature anomaly warning is issued to the energy management system of the energy storage system, prompting maintenance personnel to manually inspect or repair the battery pack.

[0052] In one specific embodiment, the system average temperature of the energy storage battery can be the mean of the average cell temperatures of all battery packs, or the median of the average cell temperatures of all battery packs. Considering that the cell temperature gradients of each battery pack may vary greatly, in this embodiment, the median of the average cell temperatures of all battery packs in the energy storage system can preferably be used as the system average temperature. Using the median can avoid the influence of extreme values ​​and better represent the typical temperature state of the system.

[0053] In one specific embodiment, when calculating the compensation benchmark, the difference between the highest cell temperature of the battery pack and the system average temperature can be selected, or the difference between the average cell temperature of the battery pack and the system average temperature can be selected, or the difference between the lowest cell temperature of the battery pack and the system average temperature can be selected. Based on the selection of the system average temperature, this embodiment preferably uses the difference between the average cell temperature of the battery pack and the system average temperature; that is, the maximum absolute value of the deviation between the average cell temperature of each battery pack in the energy storage system and the system average temperature is used as the compensation benchmark.

[0054] In a specific embodiment, the formula for calculating the compensation amount for compensating the base PWM value is as follows: K×(TT m-avg ) / T0.

[0055] In the formula, K represents a preset proportional value used to limit the maximum adjustment range of differential compensation. Its value range can be selected according to the actual needs of those skilled in the art, for example, it can be 10%~20%; T represents the cell temperature of the battery pack, T m-avg T0 represents the average system temperature, and T0 represents the compensation baseline.

[0056] It is important to know that the selection type of cell temperature T in the above compensation calculation formula is consistent with the selection type of cell temperature when calculating the compensation benchmark; that is, if the compensation benchmark is calculated using the average cell temperature, then the cell temperature T in the above compensation calculation formula is also selected as the average cell temperature.

[0057] It should be noted that in energy storage systems, the cell temperature difference ΔT < T th When the temperature difference threshold is reached, it indicates that the temperature consistency of each battery pack in the energy storage system is relatively good. Theoretically, the air-cooled fans corresponding to each battery pack can be speed-controlled according to the basic PWM value. However, considering that the intake air temperature of the battery pack and the charging and discharging state of the cells will affect the temperature control of the battery pack, the cell temperature difference ΔT < T in the energy storage system should be considered. th In such cases, the speed control of the air-cooled fan needs to be adjusted appropriately based on the intake air temperature of each battery pack and the charging and discharging status of the cells. Similarly, for energy storage systems where the cell temperature difference ΔT ≥ T...th In situations where differential speed compensation of the base PWM value is completed, it is also necessary to appropriately adjust the speed control of the air-cooled fan based on the intake air temperature of each battery pack and the charging and discharging status of the cells. By introducing judgments on abnormal cell temperature distribution and the relationship between cell temperature and ambient temperature, the temperature control strategy can be prevented from having a reverse effect on the temperature difference distribution in certain scenarios. At the same time, the introduction of judgments on cell charging and discharging status can increase the proportion of time the fan operates in the high-efficiency range, thereby improving system energy efficiency. For ease of understanding, a detailed description will be provided below.

[0058] In a specific embodiment, such as Figure 2 As shown, the inlet air temperature T of each battery pack in the energy storage system is collected. in And the cell charging and discharging status. When the cell temperature difference in the energy storage system is less than the preset temperature difference threshold, or after completing the differential compensation of the basic PWM value, the lowest air intake temperature in the energy storage system is compared with the highest cell temperature. If the highest cell temperature is less than or equal to the lowest air intake temperature, the basic PWM value corresponding to all battery packs is set to zero; otherwise, the basic PWM value corresponding to each battery pack is subject to upper and lower limit constraints and range projection based on the cell charging and discharging status.

[0059] Understandably, the inlet temperature of each battery pack can be detected by placing temperature sensors at the air inlet of each battery pack within the energy storage system. The charge / discharge status of the battery cells can be directly read from the battery management system. There are two main types of cell charge / discharge status: one where the cell is in a charge / discharge state, and the other where the cell is in a static state. When a cell is in a charge / discharge state, its temperature rise rate may be higher due to its operating characteristics; when a cell is in a static state, its temperature rise rate is lower.

[0060] It is important to know that if the highest cell temperature T of the energy storage system... max The minimum inlet air temperature of the energy storage system is less than or equal to T. in-min This indicates that the current ambient temperature has essentially exceeded the temperature of all battery cells. Under these circumstances, activating the cooling fans would cause hot outside air to enter the energy storage system, which would instead heat the battery pack, causing the cell temperature to rise instead of fall, further exacerbating the system's temperature difference. Therefore, in this embodiment, the base PWM value corresponding to all battery packs is forcibly set to zero, i.e., all cooling fans are controlled to stop operating. If the highest cell temperature T in the energy storage system... max The minimum inlet air temperature of the energy storage system is T. in-min This indicates that at least some of the battery cells are hotter than the intake air temperature, and turning on the air-cooling fan can help dissipate heat.

[0061] It is also necessary to know the highest cell temperature T of the energy storage system. maxThe minimum inlet air temperature of the energy storage system is T. in-min If the base PWM value corresponding to the battery pack is less than 50%, it means that the air-cooled fan will run at an extremely low speed, with very little actual air cooling and almost no effective airflow. However, the motor starting loss and low-speed operation of the air-cooled fan will cause some energy waste, and the noise of the air-cooled fan at low speed is also quite noticeable. Therefore, 50% can be set as the threshold for the PWM value. Air-cooled fans with a base PWM value lower than this threshold can be directly turned off, that is, the base PWM value corresponding to the air-cooled fan is set to zero. Only air-cooled fans with a base PWM value greater than or equal to 50% will have their base PWM value constrained and projected based on the charging and discharging status of the battery cells. For ease of understanding, a detailed description will be provided below.

[0062] In a specific embodiment, such as Figure 2 As shown, the specific process of constraining the upper and lower limits and projecting the range of the basic PWM value is as follows: The lower limit of the PWM value is set to 'a', the upper limit of the PWM value when the cell is in a static state is set to 'b', and the upper limit of the PWM value when the cell is in a charging / discharging state is set to 'c'; where a < b < c ≤ 100%; the specific values ​​of a, b, and c can be determined by those skilled in the art based on their actual needs. When the cells of the battery pack are in a charging / discharging state, the corresponding basic PWM value is projected proportionally to the range [a, c]; when the cells of the battery pack are in a static state, the corresponding basic PWM value is projected proportionally to the range [a, b].

[0063] Understandably, for ease of understanding, the proportional projection of the base PWM value can be described using a specific calculation formula. Taking proportional projection onto the range [a, b] as an example, the proportionally projected base PWM value can be represented as PWM*, and its calculation expression is: PWM*=a+(PWM0-a)×(ba) / (100%-a).

[0064] To further facilitate understanding, a specific example will be used to describe this in detail below.

[0065] In a specific example, we can set a=50% and b=80%; assuming the base PWM value PWM0=70%, the base PWM value is proportionally projected to the value within the range [a, b], PWM*=50%+(70%-50%)×30% / 50%=62%.

[0066] Another aspect of this application provides a computer-readable storage medium, in a preferred embodiment of which a computer program is stored on the storage medium; when the computer program is executed by a processor, it implements the above-described thermal management method for an air-cooled energy storage system.

[0067] Another aspect of this application provides an electronic device, in a preferred embodiment of which includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the above-described thermal management method for an air-cooled energy storage system.

[0068] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A thermal management method for an air-cooled energy storage system, the method comprising: Includes the following steps: Collect the cell temperature of each battery pack in the energy storage system, including the highest cell temperature, the lowest cell temperature, and the average cell temperature; The temperature rise rate and the degree of temperature rise relative to the preset target temperature are calculated based on the cell temperature of each battery pack. The obtained temperature rise rate and temperature rise degree values ​​are combined and calculated to obtain the basic PWM value for controlling the speed of the air-cooled fan corresponding to each battery pack. Calculate the cell temperature difference and system average temperature of the energy storage system. When the calculated cell temperature difference is greater than or equal to the preset temperature difference threshold, perform differential compensation on the basic PWM value according to the degree to which the cell temperature of each battery pack deviates from the system average temperature. The comprehensive calculation methods for the temperature rise rate and temperature rise degree include linear weighted summation, multiplicative modulation, and PID control. When calculating the basic PWM value, the corresponding comprehensive calculation method is adaptively selected based on the different operating modes of the air-cooled fan. The specific process is as follows: When the temperature rise rate is greater than the first threshold and the temperature rise degree is greater than the second threshold, it is determined that the air-cooled fan corresponding to the battery pack should work in emergency heat dissipation mode. At this time, the basic PWM value is obtained by multiplication modulation to comprehensively calculate the temperature rise rate and temperature rise degree. When the temperature rise rate is less than the third threshold and the temperature rise degree is less than the fourth threshold, it is determined that the air-cooled fan corresponding to the battery pack should work in energy-saving maintenance mode. At this time, the basic PWM value is obtained by comprehensively calculating the temperature rise rate and temperature rise degree using a linear weighted summation method. When the temperature rise rate is between the first and third thresholds and the temperature rise degree is between the second and fourth thresholds, it is determined that the air-cooled fan corresponding to the battery pack should work in the precise control mode. At this time, the basic PWM value is obtained by comprehensively calculating the temperature rise rate and temperature rise degree using PID control. Among them, the third threshold is less than the first threshold, and the fourth threshold is less than the second threshold.

2. The thermal management method of an air-cooled energy storage system of claim 1, wherein, The specific process of differential compensation for the base PWM value is as follows: Determine whether there exists a battery pack with the highest cell temperature in the energy storage system that corresponds to a battery pack with the lowest average cell temperature, or a battery pack with the lowest cell temperature in the energy storage system that corresponds to a battery pack with the highest average cell temperature. If present, maintain the basic PWM value corresponding to each battery pack unchanged and issue an abnormal temperature characteristic warning; If not, calculate the deviation between the cell temperature of each battery pack and the system average temperature, and use the absolute value of the maximum deviation as the compensation benchmark to compensate the basic PWM value corresponding to each battery pack.

3. The thermal management method of an air-cooled energy storage system of claim 2, wherein, The compensation amount calculation formula for compensating the basic PWM value is: K x (T-T m-avg ) / T0; In the formula, K represents a preset proportional value, T represents the temperature of the battery cell of the battery pack, T m-avg represents the system average temperature, and T0 represents a compensation reference.

4. The thermal management method of an air-cooled energy storage system of claim 1, wherein, The median of the average cell temperature across all battery packs is taken as the system average temperature, and the median temperature of the desired cell across the battery pack is taken as the cell average temperature. When calculating the compensation benchmark, the calculation is performed based on the deviation between the average cell temperature of each battery pack and the system average temperature.

5. The thermal management method of an air-cooled energy storage system according to any one of claims 1-4, wherein, Collect the air intake temperature and cell charging / discharging status of each battery pack in the energy storage system; When the cell temperature difference in the energy storage system is less than the preset temperature difference threshold, or after completing the differential compensation of the basic PWM value, the lowest air intake temperature in the energy storage system is compared with the highest cell temperature. If the highest cell temperature is less than or equal to the lowest intake temperature, the base PWM value corresponding to all battery packs is set to zero; otherwise, the base PWM value corresponding to each battery pack is subject to upper and lower limit constraints and range projection based on the cell charging and discharging status.

6. The thermal management method of an air-cooled energy storage system of claim 5, wherein, When the highest cell temperature is higher than the lowest intake air temperature, if the base PWM value corresponding to the battery pack is less than 50%, it is set to zero; otherwise, the base PWM value corresponding to each battery pack is subject to upper and lower limit constraints and range projection based on the cell charging and discharging status.

7. The thermal management method for the air-cooled energy storage system as described in claim 6, characterized in that, The battery cell charging and discharging states include a resting state and a charging and discharging state; the specific process of applying upper and lower limit constraints and range projection to the basic PWM value is as follows: The lower limit of the PWM value is set as 'a', the upper limit of the PWM value when the cell is in a static state is set as 'b', and the upper limit of the PWM value when the cell is in a charging / discharging state is set as 'c'; where a < b < c ≤ 100%; When the battery pack cells are in a charging or discharging state, the corresponding basic PWM value is proportionally projected into the range [a, c]. When the battery cells in the battery pack are in a static state, the corresponding basic PWM value is projected proportionally into the range [a, b].

8. An electronic device, characterized in that, It includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the thermal management method of the air-cooled energy storage system as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program; when the computer program is executed by a processor, it implements the thermal management method of the air-cooled energy storage system as described in any one of claims 1-7.

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