Photovoltaic energy storage battery temperature difference equalization charging method and system

Abstract

The present application relates to photovoltaic energy storage battery charging control technology field, specifically to a kind of photovoltaic energy storage battery temperature difference equalization charging method and system.For the problem that the heat generation difference of each battery cluster under photovoltaic input fluctuation is difficult to be synchronously constrained in charging distribution, leading to the expansion of temperature difference between clusters or excessive current limiting of high-temperature cluster, obtain photovoltaic energy storage charging state data to generate state object, determine equivalent temperature rise receiving margin according to battery cluster thermal state, divide photovoltaic input in current charging period into multiple charging energy slices, and establish candidate combination of charging energy slice and battery cluster, determine allowed charging current, predicted temperature rise and heat generation level, then generate temperature difference equalization charging distribution sequence according to equivalent temperature rise receiving margin, predicted temperature rise and heat generation level, control corresponding charging branch to execute charging, and update next charging period parameters according to temperature difference response data, so as to meet photovoltaic energy storage charging demand while inhibiting the expansion of battery cluster temperature difference.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic energy storage charging control technology, specifically to a method and system for temperature difference equalization charging of photovoltaic energy storage batteries. Background Technology

[0002] Photovoltaic energy storage systems typically achieve energy conversion and storage through photovoltaic arrays, converters, DC buses, energy storage battery clusters, and battery management systems. During charging control, existing methods generally determine the charging power or branch current based on data such as available power on the photovoltaic side, battery cluster voltage, current, state of charge (SOC), and temperature. When the battery cluster temperature approaches its upper limit, current limiting, power reduction, or charging termination are implemented to prevent overheating. For energy storage systems with multiple battery clusters connected in parallel or via branch lines, existing control methods also perform balancing control based on differences in SOC and temperature among the battery clusters to maintain a relatively consistent operating state during charging.

[0003] In practical applications, photovoltaic input power fluctuates with changes in sunlight, and different battery clusters exhibit varying temperature rise responses due to differences in internal resistance, heat dissipation conditions, state of charge, and current temperature. Existing methods typically focus on current-limiting control based on the current or highest temperature, failing to adequately consider photovoltaic input fluctuations, branch charging capacity, and subsequent temperature rise differences among battery clusters. This can easily lead to situations where the charging load that low-temperature battery clusters can withstand is not fully utilized, while high-temperature battery clusters continue to accumulate temperature rise under certain operating conditions. Furthermore, existing methods do not adequately utilize the feedback from the temperature difference response after execution, making it difficult to promptly correct subsequent charging allocation. Therefore, a photovoltaic energy storage battery temperature difference equalization charging method and system are needed to solve these problems. Summary of the Invention

[0004] To address the above problems, the present invention provides the following technical solution: a method for temperature difference equalization charging of photovoltaic energy storage batteries, comprising: S1. Obtain photovoltaic energy storage charging status data and generate a photovoltaic energy storage charging status object. The photovoltaic energy storage charging status object includes photovoltaic available power, photovoltaic power change slope, battery cluster thermal status, charging demand and candidate combination heating level determination parameters. S2. Determine the equivalent temperature rise receiving margin for each battery cluster based on the thermal state of the battery cluster. S3. Based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, determine the parameters, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination. S4. Generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level. S5. Control the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and collect the temperature difference response data after execution. S6. Update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

[0005] Furthermore, the photovoltaic energy storage charging status data includes photovoltaic-side data, battery cluster status data, and charging demand data; the candidate combination heating level determination parameters include a high heating threshold, a low heating threshold, a sustaining current threshold, and the applicable segment power range and current range; the generation of the photovoltaic energy storage charging status object includes: The photovoltaic array output power, bus voltage, and converter adjustable power limit in the photovoltaic side data are synchronized in time to generate the available photovoltaic power. The photovoltaic power change slope is generated based on the change in photovoltaic array output power and the time interval between adjacent synchronization moments; The thermal state of the battery cluster is generated based on the battery cluster temperature, temperature rise rate, voltage, current, state of charge, estimated internal resistance, and heat dissipation status in the battery cluster status data. The charging demand is generated based on the target charging power, target state of charge, and allowable charging time in the charging demand data. Read the candidate combination heating level determination parameters, and associate the photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand and candidate combination heating level determination parameters according to the current charging cycle to generate the photovoltaic energy storage charging state object.

[0006] Furthermore, determining the equivalent temperature rise receiving margin for each battery cluster based on the thermal state of the battery cluster includes: The target equilibrium temperature is determined based on the temperature of each battery cluster. The temperature difference received is determined by the difference between the target equilibrium temperature and the corresponding battery cluster temperature; The amount of heat suppression is determined based on the temperature rise rate and internal resistance estimate of the corresponding battery cluster; The amount of heat dissipation compensation is determined based on the heat dissipation status of the corresponding battery cluster. The temperature difference received amount and the heat dissipation compensation amount are weighted and superimposed, and the heat dissipation suppression amount is subtracted to generate an equivalent temperature rise received margin for characterizing the expected temperature rise that the corresponding battery cluster can withstand in the current charging cycle. When the temperature of the corresponding battery cluster is not lower than the target equilibrium temperature and the temperature rise rate reaches the preset temperature rise threshold, the corresponding battery cluster is marked as a restricted receiving battery cluster.

[0007] Furthermore, the process of dividing the photovoltaic input within the current charging cycle into multiple charging energy cells and establishing candidate combinations of charging energy cells and battery clusters, and determining the allowable charging current, expected temperature rise, and heat generation level for each candidate combination, includes: The target charging energy and segment power limit for the current charging cycle are determined based on the charging demand and the adjustable power limit of the converter. Based on the preset minimum adjustment cycle of the converter, the waveform inflection point of the available photovoltaic power, and the target charging energy, the current charging cycle is divided into multiple time segments; Based on the available photovoltaic power and the upper limit of the power in each time segment, determine the segment power and duration of the corresponding charging energy cell; For each candidate combination of charging energy cell and battery cluster, the allowable charging current of the candidate combination is determined based on the segment power, duration, corresponding battery cluster voltage, upper limit of branch current determined by the rated parameters of the charging branch, and state of charge. The expected heat generation of the candidate combination is calculated based on the allowable charging current, duration, and estimated internal resistance of the corresponding battery cluster. Based on the expected heat generation, the heat dissipation state of the corresponding battery cluster, and the preset equivalent heat capacity parameters of the battery cluster, the expected temperature rise of the candidate combination is calculated. Based on the expected temperature rise, allowable charging current, and the high heat threshold, low heat threshold, and sustaining current threshold in the parameters for determining the heat level of the candidate combination, the heat level of the candidate combination is determined, and the heat level includes high heat plate, flat heat plate, low heat plate, and sustaining plate.

[0008] Furthermore, generating a temperature difference equalization charging allocation sequence from the candidate combinations includes: Candidate combinations that do not meet the preset battery cluster voltage range, preset state of charge range, branch current upper limit determined by the rated parameters of the charging branch, or expected temperature rise greater than the corresponding equivalent temperature rise receiving margin are eliminated. Candidate combinations that assign high-heat or flat-heat plates to restricted receiving battery clusters are eliminated; For limited receiving battery clusters, only low-heat cell candidate combinations and maintenance cell candidate combinations with expected temperature rise not exceeding the preset limited temperature rise threshold are retained; The difference between the highest and lowest battery cluster temperatures before allocation is defined as the battery cluster temperature range before allocation. Calculate the expected temperature of each battery cluster after executing the candidate combination based on the expected temperature rise of the corresponding candidate combination, and determine the difference between the highest and lowest expected temperatures after execution as the expected temperature range after execution. The difference between the temperature range of the battery cluster before allocation and the expected temperature range after execution is determined as the expected temperature difference convergence amount for the corresponding candidate combination; When there are multiple remaining candidate combinations for the same charging energy cell, the candidate combination with the largest expected temperature difference convergence is selected and written into the temperature difference equalization charging allocation sequence. When there are no remaining candidate combinations for the same charging energy cell, the charging energy cell is marked as an energy cell to be redistributed.

[0009] Furthermore, the step of controlling the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging allocation sequence, and collecting the temperature difference response data after execution, includes: The charging energy cell identifier, battery cluster identifier, allowed charging current and duration in the temperature difference equalization charging distribution sequence are converted into branch current command, branch enable signal and bypass control signal; When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster is receiving charging energy, the corresponding branch DC / DC converter is controlled to output charging current according to the branch current command. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster receives the sustaining chip, the corresponding branch DC / DC converter is controlled to output the sustaining current. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster has not received the current charging energy cell, the corresponding bypass switch is controlled to prevent the battery cluster from receiving the current charging energy cell. The temperature difference response data is generated by collecting the changes in battery cluster temperature, temperature rise rate, state of charge increment, and branch current feedback after the execution.

[0010] Furthermore, updating the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data includes: When the temperature change of the battery cluster in the temperature difference response data is greater than the expected temperature rise of the corresponding candidate combination, and the difference between the two reaches the preset upward adjustment threshold, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is reduced, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of increasing the heating level. When the expected temperature rise of the corresponding candidate combination is greater than the temperature change of the battery cluster, and the difference between the two reaches the preset reduction threshold, and the temperature of the corresponding battery cluster is lower than the target equilibrium temperature, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is increased, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of reducing the heating level. Based on the updated equivalent temperature rise receiving margin and candidate combination heating level, the parameters are determined, and the process of temperature difference equalization charging distribution is restarted in the next charging cycle.

[0011] Furthermore, it also includes: When a charging energy cell is marked as an energy cell to be reallocated, the upper limit of the segment power corresponding to the energy cell to be reallocated is reduced, and a new candidate combination of the energy cell to be reallocated and each battery cluster is established. For the newly established candidate combinations, the allowable charging current, expected temperature rise, and heat generation level for the corresponding candidate combinations are redefined. When there are no remaining candidate combinations for the same energy cell to be redistributed within a preset number of redistribution attempts, the output of branch current command to the energy cell to be redistributed is prohibited, and a photovoltaic side-limited power command is generated to reduce the input power corresponding to the energy cell to be redistributed. When the difference between the branch current feedback and the corresponding branch current command exceeds the preset current deviation threshold, the corresponding charging branch stops executing the current charging energy cell, marks the current charging energy cell as an energy cell to be redistributed, and re-enters the temperature difference equalization charging distribution process. When the temperature of any battery cluster reaches the preset safe temperature limit, the battery cluster is marked as a thermally locked battery cluster, and the allocation of high-heat plates, flat-heat plates, and low-heat plates to the battery cluster is prohibited until the temperature of the battery cluster is lower than the preset recovery temperature.

[0012] The present invention also provides a photovoltaic energy storage battery temperature difference equalization charging system for implementing the photovoltaic energy storage battery temperature difference equalization charging method described in any of the above claims, comprising: The state object generation module is used to obtain photovoltaic energy storage charging state data and generate photovoltaic energy storage charging state objects; The equivalent temperature rise receiving margin determination module is used to determine the equivalent temperature rise receiving margin of each battery cluster based on the thermal state of the battery cluster. The charging energy cell generation module is used to determine parameters based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination. The allocation sequence generation module is used to generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level. The charging execution and response acquisition module is used to control the corresponding charging branch of each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and to collect the temperature difference response data after execution. The charging execution and response acquisition module includes a branch current command generation unit, a branch DC / DC control unit, a bypass switch control unit, a photovoltaic side limit power control unit, and a temperature difference response acquisition unit. The parameter update module is used to update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

[0013] Compared with the prior art, the present invention has the following beneficial effects: A method and system for temperature-balanced charging of photovoltaic energy storage batteries is disclosed. This method divides the photovoltaic input within the current charging cycle into multiple charging energy cells and establishes candidate combinations for these energy cells and battery clusters. A temperature-balanced charging allocation sequence is generated by combining the equivalent temperature rise receiving margin of each battery cluster, the expected temperature rise of the candidate combinations, and their heating levels. This allows photovoltaic input fluctuations, branch charging capacity, and the temperature rise response of different battery clusters to be processed in a coordinated manner during the same allocation process, thereby reducing uneven charging load distribution caused by current limiting based solely on the current temperature. Furthermore, by setting corresponding rejection, reallocation, and prohibition processes for limited-receiving battery clusters, energy cells awaiting reallocation, and thermally locked battery clusters, and updating the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data after execution, the temperature difference change can reversely correct the subsequent charging allocation basis, thereby reducing the continued accumulation of temperature rise in high-temperature battery clusters and the unutilized charging capacity of low-temperature battery clusters. Attached Figure Description

[0014] Figure 1 A flowchart of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 2 The overall flowchart of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 3 A schematic diagram of a candidate combination structure of charging energy cell and battery cluster for the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention. Figure 4 Experimental diagram of temperature range variation of battery clusters in the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 5 The diagram shows the system structure of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] Please see Figures 1 to 5 , Figure 1A flowchart of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 2 The overall flowchart of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 3 A schematic diagram of a candidate combination structure of charging energy cell and battery cluster for the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention. Figure 4 Experimental diagram of temperature range variation of battery clusters in the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention; Figure 5 This is a system structure diagram of the photovoltaic energy storage battery temperature difference equalization charging method provided by the present invention. The present invention provides a photovoltaic energy storage battery temperature difference equalization charging method, comprising: S1. Obtain photovoltaic energy storage charging status data and generate a photovoltaic energy storage charging status object. The photovoltaic energy storage charging status object includes photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand, and candidate combination heating level determination parameters.

[0018] Specifically, in this embodiment, the photovoltaic energy storage charging status data is acquired by the energy management controller from the photovoltaic-side converter, battery management system, temperature acquisition unit corresponding to each battery cluster, branch DC / DC converter, and charging scheduling unit. The energy management controller uses the current charging cycle as the processing unit, aligns the photovoltaic-side data, battery cluster status data, and charging demand data within the same charging cycle in terms of time, and writes them into a photovoltaic energy storage charging status object. This photovoltaic energy storage charging status object is used to define the usable photovoltaic input in this charging cycle, the thermal state that each battery cluster can withstand, and the parameter boundaries required for subsequent division of charging energy cells and selection of candidate combinations.

[0019] Furthermore, in one embodiment of the present invention, the photovoltaic energy storage charging status data includes photovoltaic-side data, battery cluster status data, and charging demand data; the candidate combination heating level determination parameters include a high heating threshold, a low heating threshold, a sustaining current threshold, and the applicable segment power range and current range; the generation of the photovoltaic energy storage charging status object includes: The photovoltaic array output power, bus voltage, and converter adjustable power limit in the photovoltaic side data are synchronized in time to generate the available photovoltaic power. The photovoltaic power change slope is generated based on the change in photovoltaic array output power and the time interval between adjacent synchronization moments; The thermal state of the battery cluster is generated based on the battery cluster temperature, temperature rise rate, voltage, current, state of charge, estimated internal resistance, and heat dissipation status in the battery cluster status data. The charging demand is generated based on the target charging power, target state of charge, and allowable charging time in the charging demand data. Read the candidate combination heating level determination parameters, and associate the photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand and candidate combination heating level determination parameters according to the current charging cycle to generate the photovoltaic energy storage charging state object.

[0020] Specifically, the energy management controller first uses a unified sampling time as a reference to resample or interpolate and align the photovoltaic array output power, bus voltage, and the upper limit of the converter's adjustable power. When multiple power values ​​exist at the same synchronization time, the power value corresponding to the stable range of the bus voltage is taken as the effective power, and combined with the upper limit of the converter's adjustable power to obtain the available photovoltaic power. The available photovoltaic power is used to subsequently determine the input energy that can be divided and allocated within the current charging cycle.

[0021] The slope of the photovoltaic power change is determined by the difference in output power of the photovoltaic array at adjacent synchronization moments and the time interval. In one embodiment, it is calculated as follows: ; in, For synchronization time The slope of the photovoltaic power change For synchronization time The output power of the photovoltaic array The output power of the photovoltaic array at the previous synchronization moment. This represents the time interval between adjacent synchronization moments. The calculated slope of the photovoltaic power change is written into the photovoltaic energy storage charging state object for subsequent identification of waveform inflection points in the photovoltaic input.

[0022] Subsequently, the energy management controller reads the cluster temperature, rate of temperature rise, voltage, current, state of charge (SOC), estimated internal resistance, and thermal status of each battery cluster from the battery management system. The cluster temperature indicates the current thermal level, the rate of temperature rise indicates the temperature trend, the voltage and SOC determine charging acceptability, the estimated internal resistance estimates charging heat generation, and the thermal status corrects for the projected temperature rise. These fields are then associated with the cluster identifier to generate the cluster thermal status.

[0023] Charging demand consists of target charging power, target state of charge (SOC), and allowable charging time. The target charging power defines the desired power level for the current charging cycle, the target SOC defines the target capacity state for this charging process, and the allowable charging time defines the total duration boundary for charging the energy cells. The parameters for determining the heating level of candidate combinations are pre-configured by the system based on battery type, charging branch rated parameters, and historical temperature rise response. These parameters include at least a high heating threshold, a low heating threshold, a sustaining current threshold, a segment power range, and a current range. The energy management controller reads parameters that match the current segment power range and current range for subsequent determination of the heating level of candidate combinations. After the above processing, using the current charging cycle number as the association key, the available photovoltaic power, photovoltaic power change slope, battery cluster thermal state, charging demand, and the parameters for determining the heating level of candidate combinations are encapsulated into a photovoltaic energy storage charging state object.

[0024] S2. Determine the equivalent temperature rise receiving margin for each battery cluster based on the thermal state of the battery cluster.

[0025] Specifically, in this embodiment, the equivalent temperature rise receiving margin is not determined solely by the current temperature difference, but rather considers the current temperature of the battery cluster, the rate of temperature rise, the estimated internal resistance, and the heat dissipation status simultaneously. This margin characterizes the expected temperature rise that the corresponding battery cluster can withstand during the current charging cycle. For battery clusters with lower temperatures, slower temperature rise rates, and better heat dissipation, the equivalent temperature rise receiving margin is relatively large; for battery clusters with higher temperatures, faster temperature rise rates, or higher estimated internal resistance, the equivalent temperature rise receiving margin is relatively small.

[0026] Furthermore, in one embodiment of the present invention, determining the equivalent temperature rise receiving margin of each battery cluster based on the thermal state of the battery cluster includes: The target equilibrium temperature is determined based on the temperature of each battery cluster. The temperature difference received is determined by the difference between the target equilibrium temperature and the corresponding battery cluster temperature; The amount of heat suppression is determined based on the temperature rise rate and internal resistance estimate of the corresponding battery cluster; The amount of heat dissipation compensation is determined based on the heat dissipation status of the corresponding battery cluster. The temperature difference received amount and the heat dissipation compensation amount are weighted and superimposed, and the heat dissipation suppression amount is subtracted to generate an equivalent temperature rise received margin for characterizing the expected temperature rise that the corresponding battery cluster can withstand in the current charging cycle. When the temperature of the corresponding battery cluster is not lower than the target equilibrium temperature and the temperature rise rate reaches the preset temperature rise threshold, the corresponding battery cluster is marked as a restricted receiving battery cluster.

[0027] Specifically, the energy management controller reads the temperature of all battery clusters during the current charging cycle and determines the target equalization temperature based on the battery cluster temperatures. The target equalization temperature can be the average value, median value, or a target value corrected by the upper limit of the safe temperature for each battery cluster. In this embodiment, to avoid individual abnormal temperature values ​​affecting the equalization target, the median value of the temperature of each battery cluster is preferentially used as the target equalization temperature.

[0028] The temperature difference received is determined by the difference between the target equilibrium temperature and the corresponding battery cluster temperature. When the temperature of a battery cluster is lower than the target equilibrium temperature, the difference is positive, indicating that the battery cluster can receive more temperature rise in the sense of temperature difference equilibrium; when the temperature of a battery cluster is not lower than the target equilibrium temperature, the difference is zero or a small value, indicating that the battery cluster is not suitable to continue to bear the high heat generation charging segment.

[0029] Subsequently, the heat suppression amount is determined based on the battery cluster's temperature rise rate and estimated internal resistance. A higher temperature rise rate indicates that the battery cluster is heating up rapidly; a higher estimated internal resistance indicates that more Joule heat is generated under the same current. Therefore, the energy management controller normalizes the temperature rise rate and estimated internal resistance and then weights them to obtain the heat suppression amount. The heat dissipation compensation amount is determined by the heat dissipation state, which may include liquid cooling flow rate, air cooling speed, heat sink temperature, or the on / off state of the heat dissipation circuit; the stronger the heat dissipation capacity, the greater the heat dissipation compensation amount.

[0030] In one embodiment, the equivalent temperature rise receiving margin is determined as follows: ; in, For the first The equivalent temperature rise margin for each battery cluster To achieve the target temperature equilibrium, For the first Individual battery cluster temperature, For the first The heat dissipation compensation of each battery cluster For the first The rate of temperature rise of each battery cluster For the first Estimated internal resistance of each battery cluster For calibration weights. Calculated Write the thermal state record of the corresponding battery cluster and use it as the upper limit constraint for the expected temperature rise when selecting candidate combinations in the future.

[0031] When the temperature of the corresponding battery cluster is not lower than the target equilibrium temperature and the temperature rise rate reaches the preset temperature rise threshold, the energy management controller marks the battery cluster as a restricted receiving battery cluster. The restricted receiving battery cluster is marked in the battery cluster's thermal state and is used in subsequent allocation processes to prevent high-heat or flat-heat plates from being allocated to that battery cluster.

[0032] S3. Based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, determine the parameters, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination.

[0033] For details, please refer to Figure 3 In this embodiment, the energy management controller does not charge the battery cluster as a whole based on the current photovoltaic input. Instead, it first divides the current charging cycle into multiple charging energy segments based on the changes in available photovoltaic power and charging demand. Each charging energy segment has a segment power and duration. Subsequently, each charging energy segment is paired with a battery cluster to create candidate combinations, and the allowable charging current, expected temperature rise, and heat generation level are calculated for each candidate combination, enabling subsequent allocation to be finely matched between "energy segments" and "battery clusters".

[0034] Furthermore, in one embodiment of the present invention, the step of dividing the photovoltaic input within the current charging cycle into multiple charging energy cells, establishing candidate combinations of charging energy cells and battery clusters, and determining the allowable charging current, expected temperature rise, and heat generation level of each candidate combination includes: The target charging energy and segment power limit for the current charging cycle are determined based on the charging demand and the adjustable power limit of the converter. Based on the preset minimum adjustment cycle of the converter, the waveform inflection point of the available photovoltaic power, and the target charging energy, the current charging cycle is divided into multiple time segments; Based on the available photovoltaic power and the upper limit of the power in each time segment, determine the segment power and duration of the corresponding charging energy cell; For each candidate combination of charging energy cell and battery cluster, the allowable charging current of the candidate combination is determined based on the segment power, duration, corresponding battery cluster voltage, upper limit of branch current determined by the rated parameters of the charging branch, and state of charge. The expected heat generation of the candidate combination is calculated based on the allowable charging current, duration, and estimated internal resistance of the corresponding battery cluster. Based on the expected heat generation, the heat dissipation state of the corresponding battery cluster, and the preset equivalent heat capacity parameters of the battery cluster, the expected temperature rise of the candidate combination is calculated. Based on the expected temperature rise, allowable charging current, and the high heat threshold, low heat threshold, and sustaining current threshold in the parameters for determining the heat level of the candidate combination, the heat level of the candidate combination is determined, and the heat level includes high heat plate, flat heat plate, low heat plate, and sustaining plate.

[0035] Specifically, the energy management controller determines the target charging energy based on the target charging power and the current charging cycle duration, and determines the segment power limit in conjunction with the converter's adjustable power limit. In one embodiment, the target charging energy is determined as follows: ; in, To achieve the target charging energy for the current charging cycle, To achieve the target charging power, Current charging cycle duration. The upper limit of segment power is taken as the smaller value among the target charging power, available photovoltaic power, and the upper limit of the converter's adjustable power, in order to prevent subsequent energy cells from exceeding the converter's adjustable range.

[0036] The energy management controller determines the shortest duration of a time segment based on a preset minimum adjustment period for the converter and identifies the waveform inflection point of available photovoltaic power based on the slope of photovoltaic power change. If the sign of the photovoltaic power change slope changes at adjacent synchronization moments, or if the absolute value of the photovoltaic power change slope exceeds a preset slope threshold, the corresponding synchronization moment is taken as the waveform inflection point. The energy management controller divides the current charging cycle into multiple time segments using the waveform inflection point, the minimum adjustment period, and the target charging energy as boundaries.

[0037] Subsequently, for each time segment, the energy management controller reads the available photovoltaic power within that time segment and compares it with the segment power limit to obtain the segment power of the charging energy cell; it also reads the start and end times of that time segment to obtain the duration of the charging energy cell. The charging energy cell can be represented as... ,in, For the first One charging energy chip, For segment power, For duration. This result is written to the list of charging energy cells.

[0038] Regarding the first The first charging energy cell and the first Each battery cluster, the energy management controller establishes candidate combinations. The allowable charging current is not determined solely by the charging energy cell, but rather by the segment power, the corresponding battery cluster voltage, the upper limit of the branch current, and the state of charge. In one embodiment, it is determined as follows: ; in, For the first The first charging energy cell and the first The allowable charging current for candidate combinations of battery clusters. For segment power, For the first Individual battery cluster voltage, The upper limit of the branch current is determined by the rated parameters of the charging branch. According to the first The state-of-charge (POC) allowable current is determined for each battery cluster. The calculated allowable charging current is written into this candidate combination for subsequent estimated heat generation calculations and branch current command generation.

[0039] The expected heat generation is determined based on the allowable charging current, duration, and estimated internal resistance of the corresponding battery cluster. In one embodiment, it is calculated as follows: ; in, Candidate combinations The expected heat output, To allow charging current, For the first Estimated internal resistance of each battery cluster For the first The duration of each charging energy cell. The expected heat generation is used to characterize the heat load that may occur after the energy cell is allocated to the battery cluster.

[0040] Subsequently, the energy management controller calculates the expected temperature rise based on the anticipated heat generation, heat dissipation status, and preset equivalent heat capacity parameters of the battery cluster. In one embodiment, the calculation is performed as follows: ; in, Candidate combinations The expected temperature rise, To estimate heat generation, According to the first The amount of heat dissipation offset determined by the heat dissipation state of each battery cluster For the first The preset equivalent thermal capacity parameters of each battery cluster are used. The calculated expected temperature rise is written into the candidate combination and used as the basis for judging whether the received margin of equivalent temperature rise is exceeded.

[0041] The heating rating of candidate energy cells is determined based on the expected temperature rise, allowable charging current, high heating threshold, low heating threshold, and sustaining current threshold. When the expected temperature rise reaches the high heating threshold, the candidate cell is marked as a high-heat cell; when the expected temperature rise is below the high heating threshold but above the low heating threshold, the candidate cell is marked as a level heating cell; when the expected temperature rise is not higher than the low heating threshold and the allowable charging current is greater than the sustaining current threshold, the candidate cell is marked as a low-heat cell; and when the allowable charging current is not higher than the sustaining current threshold, the candidate cell is marked as a sustaining cell. Therefore, the same energy cell can have different expected temperature rises and heating ratings relative to different battery clusters.

[0042] S4. Generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level.

[0043] Specifically, in this embodiment, the energy management controller uses each charging energy cell as the allocation target and filters the remaining candidate combinations from the candidate combinations formed by the charging energy cell and each battery cluster. During the filtering process, the battery cluster voltage, state of charge, branch current limit, expected temperature rise, equivalent temperature rise receiving margin, and heating level are considered simultaneously to avoid allocating high heat loads to battery clusters that are already too hot or are heating up too quickly. Subsequently, candidate combinations are selected based on the expected temperature difference convergence and written into the temperature difference equalization charging allocation sequence.

[0044] Furthermore, in one embodiment of the present invention, generating a temperature difference equalization charging allocation sequence from the candidate combinations includes: Candidate combinations that do not meet the preset battery cluster voltage range, preset state of charge range, branch current upper limit determined by the rated parameters of the charging branch, or expected temperature rise greater than the corresponding equivalent temperature rise receiving margin are eliminated. Candidate combinations that assign high-heat or flat-heat plates to restricted receiving battery clusters are eliminated; For limited receiving battery clusters, only low-heat cell candidate combinations and maintenance cell candidate combinations with expected temperature rise not exceeding the preset limited temperature rise threshold are retained; The difference between the highest and lowest battery cluster temperatures before allocation is defined as the battery cluster temperature range before allocation. Calculate the expected temperature of each battery cluster after executing the candidate combination based on the expected temperature rise of the corresponding candidate combination, and determine the difference between the highest and lowest expected temperatures after execution as the expected temperature range after execution. The difference between the temperature range of the battery cluster before allocation and the expected temperature range after execution is determined as the expected temperature difference convergence amount for the corresponding candidate combination; When there are multiple remaining candidate combinations for the same charging energy cell, the candidate combination with the largest expected temperature difference convergence is selected and written into the temperature difference equalization charging allocation sequence. When there are no remaining candidate combinations for the same charging energy cell, the charging energy cell is marked as an energy cell to be redistributed.

[0045] Specifically, the energy management controller first performs a basic safety screening of candidate combinations. For any candidate combination, if the corresponding battery cluster voltage exceeds a preset battery cluster voltage range, or the state of charge exceeds a preset state of charge range, or the permissible charging current exceeds the upper limit of the branch current determined by the rated parameters of the charging branch, then the candidate combination is eliminated. If the expected temperature rise of the candidate combination is greater than the equivalent temperature rise acceptance margin of the corresponding battery cluster, then the candidate combination is also eliminated. The above elimination results form the remaining candidate combinations.

[0046] Subsequently, the energy management controller reads the restricted-reception battery cluster markers and performs a secondary screening of candidate combinations involving restricted-reception battery clusters. If a candidate combination's heat generation level is high-heat or flat-heat, and the corresponding battery cluster is a restricted-reception battery cluster, then the candidate combination is eliminated. For restricted-reception battery clusters, only low-heat candidate combinations and maintenance candidate combinations with expected temperature rise not exceeding a preset restricted temperature rise threshold are retained. The preset restricted temperature rise threshold can be calibrated based on the upper limit of the battery's safe temperature, the distance between the current temperature and the recovery temperature, and the heat dissipation status.

[0047] The temperature range of the battery clusters before allocation is determined as follows: ; in, Due to the extreme temperature difference of the battery clusters before distribution, These represent the temperatures of each battery cluster during the current charging cycle. This represents the number of battery clusters. The temperature range of the battery clusters before allocation is used to characterize the temperature difference level between the current battery clusters.

[0048] For a given remaining candidate combination The energy management controller adds the expected temperature rise of the candidate combination to the current temperature of the corresponding battery cluster to obtain the expected temperature of each battery cluster after execution. For battery clusters that have not received charging energy, their expected temperature can be determined based on the current temperature or a temperature corrected for natural heat dissipation. The expected temperature range after execution is determined as follows: ; in, To execute candidate combinations The expected temperature afterwards is extremely poor. The expected temperatures for each battery cluster after executing this candidate combination are determined as follows: ; in, Candidate combinations The expected convergence of the temperature difference. If A positive value indicates that the temperature range of the battery cluster is expected to decrease after implementing this candidate combination; if... A value of zero or negative indicates that the candidate combination does not contribute to the temperature difference equilibrium or may increase the temperature difference.

[0049] When multiple candidate combinations of the same charging energy cell exist, the energy management controller compares the expected temperature difference convergence of each remaining candidate combination and selects the candidate combination with the largest expected temperature difference convergence to write into the temperature difference equalization charging allocation sequence. The temperature difference equalization charging allocation sequence includes at least the charging energy cell identifier, battery cluster identifier, allowable charging current, duration, and heat generation level. When no remaining candidate combinations exist for the same charging energy cell, it indicates that the charging energy cell cannot be safely allocated to any battery cluster under the current segment power. The energy management controller marks the charging energy cell as an energy cell to be reallocated and proceeds to subsequent reallocation processing.

[0050] S5. Control the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and collect the temperature difference response data after execution.

[0051] For details, please refer to Figure 2 In this embodiment, the energy management controller controls the charging of each energy cell sequentially according to the temperature difference equalization charging allocation sequence. Each battery cluster is connected to the DC bus through a corresponding charging branch, which includes a branch DC / DC converter and a bypass switch. The energy management controller outputs a branch current command to the corresponding branch DC / DC converter based on the allocation result, and determines whether the corresponding battery cluster receives the current charging energy cell's output branch enable signal or bypass control signal.

[0052] Furthermore, in one embodiment of the present invention, the step of controlling the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging allocation sequence, and collecting the temperature difference response data after execution, includes: The charging energy cell identifier, battery cluster identifier, allowed charging current and duration in the temperature difference equalization charging distribution sequence are converted into branch current command, branch enable signal and bypass control signal; When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster is receiving charging energy, the corresponding branch DC / DC converter is controlled to output charging current according to the branch current command. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster receives the sustaining chip, the corresponding branch DC / DC converter is controlled to output the sustaining current. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster has not received the current charging energy cell, the corresponding bypass switch is controlled to prevent the battery cluster from receiving the current charging energy cell. The temperature difference response data is generated by collecting the changes in battery cluster temperature, temperature rise rate, state of charge increment, and branch current feedback after the execution.

[0053] Specifically, the energy management controller reads the charging energy cell identifier, battery cluster identifier, allowed charging current, and duration from the temperature difference equalization charging allocation sequence. It then converts the allowed charging current into the corresponding branch current command for the charging branch, the duration into the command hold time, and the battery cluster identifier into the branch enable address. For battery clusters that have not been allocated the current charging energy cell, the energy management controller generates a bypass control signal to prevent the battery cluster from receiving the charging current corresponding to the current charging energy cell.

[0054] When the temperature-equalization charging allocation sequence indicates that the corresponding battery cluster is receiving charging energy, the energy management controller enables the corresponding branch DC / DC converter and outputs charging current according to the branch current command. The branch DC / DC converter maintains the corresponding output for the duration and returns branch current feedback in real time. When the temperature-equalization charging allocation sequence indicates that the corresponding battery cluster is receiving sustaining energy, the energy management controller controls the corresponding branch DC / DC converter to output a sustaining current not exceeding the sustaining current threshold, so as to maintain the connection state of the battery cluster in the charging schedule and reduce the heat load of the battery cluster.

[0055] When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster has not received the current charging energy cell, the energy management controller controls the corresponding bypass switch to enter the bypass state, so that the battery cluster does not receive the current charging energy cell. For the energy cell to be redistributed that has not been received by any battery cluster, the energy management controller does not output the corresponding branch current command, or generates a photovoltaic side-limited power command to reduce the input power corresponding to the energy cell.

[0056] After completing the current charging energy cell operation, the energy management controller collects the following data: battery cluster temperature change, temperature rise rate change, state of charge increment, and branch current feedback. The battery cluster temperature change is obtained from the temperature difference before and after operation; the temperature rise rate change is obtained from the temperature rise rate difference before and after operation; the state of charge increment is obtained from the state of charge change uploaded by the battery management system; and the branch current feedback is uploaded by the branch DC / DC converter. These data are associated with the charging energy cell identifier and the battery cluster identifier to generate temperature difference response data.

[0057] S6. Update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

[0058] Specifically, in this embodiment, the energy management controller compares the temperature difference response data after execution with the expected temperature rise before execution to determine whether the estimation of the heating level and equivalent temperature rise receiving margin of the candidate combination in the current charging cycle is too high or too low. If the actual temperature rise is greater than the expected temperature rise, it indicates that the heating of the corresponding battery cluster or the corresponding power and current range is underestimated, and the equivalent temperature rise receiving margin needs to be reduced and the heating level increased in the next charging cycle. If the actual temperature rise is less than the expected temperature rise and the battery cluster temperature is still lower than the target equilibrium temperature, it indicates that the battery cluster still has a certain temperature rise receiving capability, and the equivalent temperature rise receiving margin can be appropriately increased and the heating level reduced in the next charging cycle.

[0059] Furthermore, in one embodiment of the present invention, updating the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data includes: When the temperature change of the battery cluster in the temperature difference response data is greater than the expected temperature rise of the corresponding candidate combination, and the difference between the two reaches the preset upward adjustment threshold, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is reduced, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of increasing the heating level. When the expected temperature rise of the corresponding candidate combination is greater than the temperature change of the battery cluster, and the difference between the two reaches the preset reduction threshold, and the temperature of the corresponding battery cluster is lower than the target equilibrium temperature, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is increased, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of reducing the heating level. Based on the updated equivalent temperature rise receiving margin and candidate combination heating level, the parameters are determined, and the process of temperature difference equalization charging distribution is restarted in the next charging cycle.

[0060] Specifically, the energy management controller reads the temperature change of the battery cluster from the temperature difference response data and reads the expected temperature rise calculated before execution for the corresponding candidate combination. If the temperature change of the battery cluster is greater than the expected temperature rise, the difference between the two is calculated. When this difference reaches a preset upward adjustment threshold, it indicates that the heat generation impact of the candidate combination has been underestimated. At this time, the energy management controller reduces the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle, and the reduction can be determined proportionally to the difference.

[0061] In one embodiment, the equivalent temperature rise receiving margin for the next charging cycle is corrected as follows:

[0062] in, For the first The equivalent temperature rise margin for each battery cluster in the next charging cycle For the first The equivalent temperature rise margin for each battery cluster during the current charging cycle This refers to the temperature change of the battery cluster in the temperature difference response data. Candidate combinations The expected temperature rise, and This is a correction factor. The first term in the formula is used to reduce the receiving margin when the actual temperature rise is higher than expected, and the second term is used to increase the receiving margin when the actual temperature rise is lower than expected but the temperature conditions are met.

[0063] Simultaneously, the energy management controller determines the parameters for the corresponding candidate combination's heating level based on the segment power range and current range of the candidate combinations. When the actual temperature rise exceeds the expected temperature rise and the difference reaches a preset upward adjustment threshold, the corresponding high or low heating threshold is adjusted towards a more stringent direction, making it easier for candidate combinations with the same power and current ranges to be judged as having a higher heating level in the next charging cycle. When the expected temperature rise exceeds the actual temperature rise and the difference reaches a preset downward adjustment threshold, and the corresponding battery cluster temperature is lower than the target equalization temperature, the corresponding parameters are adjusted towards a lower heating level, allowing battery clusters with lower temperatures and less actual heating to receive more suitable charging energy in the next charging cycle. After the update is completed, the energy management controller uses the updated equivalent temperature rise receiving margin and candidate combination heating level determination parameters to re-enter the temperature difference equalization charging allocation process for the next charging cycle.

[0064] Furthermore, in one embodiment provided by the present invention, the method further includes: When a charging energy cell is marked as an energy cell to be reallocated, the upper limit of the segment power corresponding to the energy cell to be reallocated is reduced, and a new candidate combination of the energy cell to be reallocated and each battery cluster is established. For the newly established candidate combinations, the allowable charging current, expected temperature rise, and heat generation level for the corresponding candidate combinations are redefined. When there are no remaining candidate combinations for the same energy cell to be redistributed within a preset number of redistribution attempts, the output of branch current command to the energy cell to be redistributed is prohibited, and a photovoltaic side-limited power command is generated to reduce the input power corresponding to the energy cell to be redistributed. When the difference between the branch current feedback and the corresponding branch current command exceeds the preset current deviation threshold, the corresponding charging branch stops executing the current charging energy cell, marks the current charging energy cell as an energy cell to be redistributed, and re-enters the temperature difference equalization charging distribution process. When the temperature of any battery cluster reaches the preset safe temperature limit, the battery cluster is marked as a thermally locked battery cluster, and the allocation of high-heat plates, flat-heat plates, and low-heat plates to the battery cluster is prohibited until the temperature of the battery cluster is lower than the preset recovery temperature.

[0065] For details, please refer to Figure 2 When a charging energy cell has no remaining candidate combinations and is marked as an energy cell to be reallocated, the energy management controller does not directly discard the charging energy cell. Instead, it first lowers the segment power limit corresponding to the energy cell to be reallocated. The lowered segment power limit is used to redetermine the segment power of the energy cell to be reallocated and to re-establish the candidate combinations of the energy cell to be reallocated with each battery cluster.

[0066] Subsequently, the energy management controller re-determines the candidate combination parameters for the newly established candidate combinations according to the aforementioned calculation process of allowable charging current, expected heat generation, expected temperature rise, and heating level, and performs candidate combination screening again. If no remaining candidate combinations are found for the same energy cell to be redistributed within a preset number of redistribution attempts, it indicates that the energy cell is not suitable for further redistribution under the current photovoltaic input and cell cluster thermal state. The energy management controller prohibits the output of branch current commands to the energy cell to be redistributed and generates a photovoltaic side-limiting power command to reduce the input power corresponding to the energy cell to be redistributed.

[0067] During the execution of the charging branch, the energy management controller also compares the difference between the branch current feedback and the corresponding branch current command. When the difference exceeds the preset current deviation threshold, it indicates that the charging branch has failed to stably execute the current charging energy cell according to the allocation sequence. The energy management controller stops the corresponding charging branch from executing the current charging energy cell, marks the current charging energy cell as an energy cell to be reallocated, and re-enters the temperature difference equalization charging allocation process.

[0068] When the temperature of any battery cluster reaches the preset safe upper temperature limit, the energy management controller marks the battery cluster as a thermally locked battery cluster. A thermally locked battery cluster will no longer accept high-temperature, flat-temperature, or low-temperature plates; it will only be allowed to accept maintenance plates or enter bypass mode when the safety policy is met. This thermally locked state continues until the battery cluster temperature falls below the preset recovery temperature to prevent the battery cluster from continuing to bear the charging heat load when the temperature is close to the safe boundary.

[0069] This invention also provides a photovoltaic energy storage battery temperature difference equalization charging system for implementing the above-mentioned photovoltaic energy storage battery temperature difference equalization charging method, comprising: The state object generation module is used to obtain photovoltaic energy storage charging state data and generate photovoltaic energy storage charging state objects; The equivalent temperature rise receiving margin determination module is used to determine the equivalent temperature rise receiving margin of each battery cluster based on the thermal state of the battery cluster. The charging energy cell generation module is used to determine parameters based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination. The allocation sequence generation module is used to generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level. The charging execution and response acquisition module is used to control the corresponding charging branch of each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and to collect the temperature difference response data after execution. The charging execution and response acquisition module includes a branch current command generation unit, a branch DC / DC control unit, a bypass switch control unit, a photovoltaic side limit power control unit, and a temperature difference response acquisition unit. The parameter update module is used to update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

[0070] For details, please refer to Figure 5 In this embodiment, the state object generation module is communicatively connected to the photovoltaic-side converter, the battery management system, and the charging scheduling unit to form photovoltaic energy storage charging state objects. The equivalent temperature rise receiving margin determination module reads the thermal state of the battery clusters and generates the equivalent temperature rise receiving margin for each cluster. The charging energy cell generation module generates charging energy cells based on the photovoltaic input and charging requirements, and establishes candidate combinations with the battery clusters. The allocation sequence generation module generates a temperature difference equalization charging allocation sequence based on the candidate combination screening results and the expected temperature difference convergence. The charging execution and response acquisition module converts the allocation sequence into branch current commands, branch enable signals, bypass control signals, and photovoltaic-side power limiting commands, and acquires the temperature difference response data after execution. The parameter update module corrects the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data, enabling the system to adjust subsequent allocation strategies according to the actual temperature rise response during continuous charging cycles.

[0071] Please refer to the experimental verification. Figure 4 A photovoltaic energy storage charging platform containing multiple parallel battery clusters was selected for continuous charging cycle testing, and the conventional scheme of limiting current based on the highest temperature, the scheme of allocating charging power according to the current temperature, and the scheme of the present invention were compared. Figure 4In the diagram, the horizontal axis represents the charging cycle, and the vertical axis represents the temperature range of the battery clusters. During the experiment, each scheme operated under the same initial temperature difference, the same photovoltaic input variation conditions, and the same target charging demand. Scheme 1, which only limited the total charging power based on the highest temperature battery cluster, failed to distinguish the heating effects of different photovoltaic input segments on each battery cluster, resulting in the temperature range of the battery clusters remaining at a high level in some charging cycles. Scheme 2 allocated power based on the current battery cluster temperature, which gradually reduced the temperature range, but it did not combine the charging energy slices, expected temperature rise, and heating level for candidate combination screening, resulting in a slower temperature difference convergence speed. The present invention first divides the charging energy slices within each charging cycle, and then generates a temperature-balanced charging allocation sequence based on the equivalent temperature rise receiving margin, expected temperature rise, and heating level. This allows battery clusters with lower temperatures and temperature rise receiving capabilities to preferentially receive suitable charging energy slices, while restricting battery clusters with higher temperatures or faster temperature rises from receiving high-heat segments. Figure 4 It can be seen that the temperature difference between battery clusters corresponding to the present invention shows a continuous decreasing trend with the increase of charging cycle, indicating that the present invention can suppress the expansion of temperature difference between battery clusters while meeting the charging requirements of photovoltaic energy storage.

[0072] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for temperature difference equalization charging of photovoltaic energy storage batteries, characterized in that, include: S1. Obtain photovoltaic energy storage charging status data and generate a photovoltaic energy storage charging status object. The photovoltaic energy storage charging status object includes photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand, and candidate combination heating level determination parameters. The candidate combination heating level determination parameters include high heating threshold, low heating threshold, sustaining current threshold, and the segment power range and current range to which the high heating threshold, the low heating threshold, and the sustaining current threshold are applicable. S2. Determine the equivalent temperature rise receiving margin for each battery cluster based on the thermal state of the battery cluster. S3. Based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, determine the parameters, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination. S4. Generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level. S5. Control the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and collect the temperature difference response data after execution. S6. Update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

2. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 1, characterized in that, The photovoltaic energy storage charging status data includes photovoltaic-side data, battery cluster status data, and charging demand data. The generation of the photovoltaic energy storage charging status object includes: The photovoltaic array output power, bus voltage, and converter adjustable power limit in the photovoltaic side data are synchronized in time to generate the available photovoltaic power. The photovoltaic power change slope is generated based on the change in photovoltaic array output power and the time interval between adjacent synchronization moments; The thermal state of the battery cluster is generated based on the battery cluster temperature, temperature rise rate, voltage, current, state of charge, estimated internal resistance, and heat dissipation status in the battery cluster status data. The charging demand is generated based on the target charging power, target state of charge, and allowable charging time in the charging demand data. Read the candidate combination heating level determination parameters, and associate the photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand and candidate combination heating level determination parameters according to the current charging cycle to generate the photovoltaic energy storage charging state object.

3. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 2, characterized in that, The step of determining the equivalent temperature rise receiving margin for each battery cluster based on the thermal state of the battery cluster includes: The target equilibrium temperature is determined based on the temperature of each battery cluster. The temperature difference received is determined by the difference between the target equilibrium temperature and the corresponding battery cluster temperature; The amount of heat suppression is determined based on the temperature rise rate and internal resistance estimate of the corresponding battery cluster; The amount of heat dissipation compensation is determined based on the heat dissipation status of the corresponding battery cluster. The temperature difference received amount and the heat dissipation compensation amount are weighted and superimposed, and the heat dissipation suppression amount is subtracted to generate an equivalent temperature rise received margin for characterizing the expected temperature rise that the corresponding battery cluster can withstand in the current charging cycle. When the temperature of the corresponding battery cluster is not lower than the target equilibrium temperature and the temperature rise rate reaches the preset temperature rise threshold, the corresponding battery cluster is marked as a restricted receiving battery cluster.

4. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 3, characterized in that, The process of dividing the photovoltaic input within the current charging cycle into multiple charging energy cells, establishing candidate combinations of charging energy cells and battery clusters, and determining the allowable charging current, expected temperature rise, and heat generation level for each candidate combination includes: The target charging energy and segment power limit for the current charging cycle are determined based on the charging demand and the adjustable power limit of the converter. Based on the preset minimum adjustment cycle of the converter, the waveform inflection point of the available photovoltaic power, and the target charging energy, the current charging cycle is divided into multiple time segments; Based on the available photovoltaic power and the upper limit of the power in each time segment, determine the segment power and duration of the corresponding charging energy cell; For each candidate combination of charging energy cell and battery cluster, the allowable charging current of the candidate combination is determined based on the segment power, duration, corresponding battery cluster voltage, upper limit of branch current determined by the rated parameters of the charging branch, and state of charge. The expected heat generation of the candidate combination is calculated based on the allowable charging current, duration, and estimated internal resistance of the corresponding battery cluster. Based on the expected heat generation, the heat dissipation state of the corresponding battery cluster, and the preset equivalent heat capacity parameters of the battery cluster, the expected temperature rise of the candidate combination is calculated. Based on the expected temperature rise, allowable charging current, and the high heat threshold, low heat threshold, and sustaining current threshold in the parameters for determining the heat level of the candidate combination, the heat level of the candidate combination is determined, and the heat level includes high heat plate, flat heat plate, low heat plate, and sustaining plate.

5. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 4, characterized in that, The step of generating a temperature difference equalization charging allocation sequence from the candidate combinations includes: Candidate combinations that meet any of the following conditions will be eliminated: do not meet the preset battery cluster voltage range; do not meet the preset state of charge range; allowable charging current is greater than the upper limit of the branch current determined by the rated parameters of the charging branch; expected temperature rise is greater than the corresponding equivalent temperature rise receiving margin. Candidate combinations that assign high-heat or flat-heat plates to restricted receiving battery clusters are eliminated; For limited receiving battery clusters, only low-heat cell candidate combinations and maintenance cell candidate combinations with expected temperature rise not exceeding the preset limited temperature rise threshold are retained; The difference between the highest and lowest battery cluster temperatures before allocation is defined as the battery cluster temperature range before allocation. Calculate the expected temperature of each battery cluster after executing the candidate combination based on the expected temperature rise of the corresponding candidate combination, and determine the difference between the highest and lowest expected temperatures after execution as the expected temperature range after execution. The difference between the temperature range of the battery cluster before allocation and the expected temperature range after execution is determined as the expected temperature difference convergence amount for the corresponding candidate combination; When there are multiple remaining candidate combinations for the same charging energy cell, the candidate combination with the largest expected temperature difference convergence is selected and written into the temperature difference equalization charging allocation sequence. When there are no remaining candidate combinations for the same charging energy cell, the charging energy cell is marked as an energy cell to be redistributed.

6. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 5, characterized in that, The step of controlling the charging branch corresponding to each battery cluster to perform charging according to the temperature difference equalization charging allocation sequence, and collecting the temperature difference response data after execution, includes: The charging energy cell identifier, battery cluster identifier, allowed charging current and duration in the temperature difference equalization charging distribution sequence are converted into branch current command, branch enable signal and bypass control signal; When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster is receiving charging energy, the corresponding branch DC / DC converter is controlled to output charging current according to the branch current command. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster receives the sustaining chip, the corresponding branch DC / DC converter is controlled to output the sustaining current. When the temperature difference equalization charging distribution sequence indicates that the corresponding battery cluster has not received the current charging energy cell, the corresponding bypass switch is controlled to prevent the battery cluster from receiving the current charging energy cell. The temperature difference response data is generated by collecting the changes in battery cluster temperature, temperature rise rate, state of charge increment, and branch current feedback after the execution.

7. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 6, characterized in that, The step of updating the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data includes: When the temperature change of the battery cluster in the temperature difference response data is greater than the expected temperature rise of the corresponding candidate combination, and the difference between the two reaches the preset upward adjustment threshold, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is reduced, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of increasing the heating level. When the expected temperature rise of the corresponding candidate combination is greater than the temperature change of the battery cluster, and the difference between the two reaches the preset reduction threshold, and the temperature of the corresponding battery cluster is lower than the target equilibrium temperature, the equivalent temperature rise receiving margin of the corresponding battery cluster in the next charging cycle is increased, and the candidate combination heating level determination parameters corresponding to the segment power range and current range of the candidate combination are corrected in the direction of reducing the heating level. Based on the updated equivalent temperature rise receiving margin and candidate combination heating level, the parameters are determined, and the process of temperature difference equalization charging distribution is restarted in the next charging cycle.

8. The photovoltaic energy storage battery temperature difference equalization charging method according to claim 6, characterized in that, Also includes: When a charging energy cell is marked as an energy cell to be reallocated, the upper limit of the segment power corresponding to the energy cell to be reallocated is reduced, and a new candidate combination of the energy cell to be reallocated and each battery cluster is established. For the newly established candidate combinations, the allowable charging current, expected temperature rise, and heat generation level for the corresponding candidate combinations are redefined. When there are no remaining candidate combinations for the same energy cell to be redistributed within a preset number of redistribution attempts, the output of branch current command to the energy cell to be redistributed is prohibited, and a photovoltaic side-limited power command is generated to reduce the input power corresponding to the energy cell to be redistributed. When the difference between the branch current feedback and the corresponding branch current command exceeds the preset current deviation threshold, the execution of the corresponding charging branch on the current charging energy cell is stopped, the current charging energy cell is marked as an energy cell to be redistributed, and the temperature difference equalization charging distribution process is re-entered. When the temperature of any battery cluster reaches the preset safe temperature limit, the battery cluster is marked as a thermally locked battery cluster, and the allocation of high-heat plates, flat-heat plates, and low-heat plates to the battery cluster is prohibited until the temperature of the battery cluster is lower than the preset recovery temperature.

9. A photovoltaic energy storage battery temperature difference equalization charging system, characterized in that, A method for implementing the temperature difference equalization charging of a photovoltaic energy storage battery according to any one of claims 1 to 8 includes: The state object generation module is used to acquire photovoltaic energy storage charging state data and generate photovoltaic energy storage charging state objects. The photovoltaic energy storage charging state objects include photovoltaic available power, photovoltaic power change slope, battery cluster thermal state, charging demand, and candidate combination heating level determination parameters. The candidate combination heating level determination parameters include high heating threshold, low heating threshold, sustaining current threshold, and the segment power range and current range to which the high heating threshold, the low heating threshold, and the sustaining current threshold are applicable. The equivalent temperature rise receiving margin determination module is used to determine the equivalent temperature rise receiving margin of each battery cluster based on the thermal state of the battery cluster. The charging energy cell generation module is used to determine parameters based on the available photovoltaic power, the slope of photovoltaic power change, charging demand, the thermal state of the battery cluster and the heating level of the candidate combination, divide the photovoltaic input in the current charging cycle into multiple charging energy cells, establish candidate combinations of charging energy cells and battery clusters, and determine the allowable charging current, expected temperature rise and heating level of each candidate combination. The allocation sequence generation module is used to generate a temperature difference equalization charging allocation sequence from the candidate combinations based on the equivalent temperature rise receiving margin, the expected temperature rise, and the heating level. The charging execution and response acquisition module is used to control the corresponding charging branch of each battery cluster to perform charging according to the temperature difference equalization charging distribution sequence, and to collect the temperature difference response data after execution. The charging execution and response acquisition module includes a branch current command generation unit, a branch DC / DC control unit, a bypass switch control unit, a photovoltaic side limit power control unit, and a temperature difference response acquisition unit. The parameter update module is used to update the equivalent temperature rise receiving margin and candidate combination heating level determination parameters for the next charging cycle based on the temperature difference response data.

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