Storage battery temperature equalization control system and method

Abstract

The invention relates to a storage battery temperature equalization control system and method, belongs to the technical field of batteries, and solves the problem of safety accidents or rapid attenuation of a storage battery caused by violation of existing voltage equalization and temperature compensation. The system comprises a storage battery and an equalization circuit, the storage battery comprises a parallel battery pack, the equalization circuit comprises a plurality of diodes, the anode of each unit battery in the parallel battery pack is connected in series to the anode of one diode, and the cathode of the diode is connected to a first common node; the negative electrode of each unit battery in the parallel battery pack is connected in series to one end of one current-limiting resistor, and the other end of the current-limiting resistor is connected to a second common node; and an equalization resistor and an electronic switch for connecting the equalization resistor and the electronic switch in series and then connecting the equalization resistor and the electronic switch connected in series between the first and second common nodes. Temperature compensation is carried out in the charging process of the storage battery, and a large amount of overcharge, undercharge and the like are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a storage battery temperature equalization control system and method. BACKGROUND

[0002] The lead-carbon battery is a lead-acid battery with special carbon materials (such as graphene) added to the negative active material. It is also a type of lead-acid battery. By developing high-performance materials, graphene materials are applied in the positive grid alloy of lead-acid batteries and in the negative active material through experimental screening, and the suitable composite ratio is optimized. At the same time, hydrogen evolution inhibition materials are used to produce high-performance graphene-based lead-carbon super batteries. The active material has a high specific surface area, which improves the charge acceptance capacity and efficiency, prevents negative sulfurization, and improves the reversibility of the active material. The cycle life of the lead-acid battery under partial state of charge is greatly improved, especially the 50%-70% 70DOD cycle life reaches 4500 cycles. Currently, it is moving towards a longer life goal.

[0003] 2. Lead-carbon energy storage system

[0004] The successful development of long-life lead-carbon batteries greatly expands the application field of lead-acid batteries, and energy storage systems are one of the main target markets. Energy storage systems require high safety, high reliability, and long life, etc. So many batteries are connected in parallel and series to form a system to provide users with use, which requires high safety, high reliability, and long life, etc. So many batteries are connected in parallel and series, which will affect each other during charging and discharging due to the consistency of the batteries. The main performance is as follows:

[0005] (1) The lead-acid battery has different charging acceptance capacity and side reactions, which leads to inconsistent charging efficiency, ultimately leading to differences in battery capacity, overcharging of some batteries, and overdischarging of some batteries, which greatly affects the life of the battery.

[0006] (2) During the manufacturing of the lead-acid battery, excessive consumption of sulfuric acid during the acid addition process leads to the dissolution of lead in the active material, which ultimately forms lead dendrites during charging and discharging, forms micro-short circuits, and brings in foreign matter during the assembly process, causing short circuits. During use, it will affect the performance of other batteries, and even pose a safety hazard;

[0007] (3) During the manufacturing of the lead-acid battery, impurities are introduced, causing self-discharge of the battery, which leads to inconsistent state of charge of the battery, and the battery with large self-discharge is prone to "lagging battery", which affects the performance of the entire battery.

[0008] (4) The traditional system architecture of the lead-acid battery has the following types:

[0009] Figure 1 is a typical traditional energy storage battery management system. Single batteries are connected in series to form a pack (i.e., a battery group), and then multiple battery packs are connected in series to form a battery module, each battery module can output power and charge to the PCS (Power Conversion System, energy storage inverter system) alone, or multiple battery modules can be connected in parallel to output power and charge to the PCS.

[0010] Each battery has a corresponding battery management circuit BMU. The main function of the traditional battery management circuit BMU is to detect the battery temperature, voltage, charging and discharging current, and the detected data is transmitted to the BMS system through the communication system. The BMS system performs calculations and controls the strategy according to the calculations and system requirements, and then sends control strategy instructions to related devices, including the battery management circuit BMU. The battery management circuit BMU receives the equalization instructions from the BMS and performs equalization operations (active or passive). Specifically, the battery management circuit BMU is the "basic unit" of battery management, usually referring to the hardware module within the battery group, responsible for monitoring a single parameter of the battery (such as voltage, temperature) and basic protection (such as overcharging, overdischarging). The battery management system BMS is the "complete system" of battery management, including hardware and software, responsible for the global management of the battery group, covering safety protection, state estimation, equalization control, communication scheduling and other functions.

[0011] In addition, the battery equalization circuit has an equalization function, that is, according to the detection of the battery voltage, by comparing the voltage difference, when the voltage difference reaches a specified value, the equalization circuit controls the equalization to start, and when the voltage difference is less than the specified value, the equalization is turned off. The purpose of the equalization function is to make the voltage or capacity of each cell consistent.

[0012] Advantages and disadvantages of the system: each battery has a separate battery management circuit BMU, which can well control the voltage consistency of each unit battery and achieve the effect of voltage equalization. In this energy storage system, all batteries are connected in series, and the minimum capacity of a single battery is the capacity of this module of batteries. The battery management circuit BMU manages each cell, and the number is large. If a large capacity is required, a large number of battery modules need to be connected in parallel to meet the requirements. The management circuit and system are complex, prone to failure, and the cost is high. At the same time, since the management system only has temperature detection and abnormal temperature alarm and power-off function, without temperature control function, it is easy to cause thermal runaway.

[0013] Figure 2 and Figure 3 is an improvement based on Figure 1 , mainly using a structure of parallel connection first and series connection later, each parallel battery group has 2-n unit batteries, and all parallel batteries have only one battery management circuit BMU.

[0014] The advantages of this management system are: the battery management circuit BMU adopted is Figure 1 n times (n is the number of parallel connected batteries), and the capacity of each string is Figure 1 n times (n is the number of parallel connected batteries). The disadvantages are: there are differences in internal resistance and other factors among the parallel connected battery cells, which easily causes a bias current phenomenon, that is, there is a bias in the charging and discharging current of the battery. During discharging, the bias causes the battery with a large current to have a large output capacity and a large output, and is in a deep charging and discharging state, which leads to a shortened service life. During charging, the battery with a large charging current is prone to temperature rise and "thermal runaway", that is, the charging current causes the temperature to rise, and the temperature rise in turn increases the charging current, and the thermal runaway leads to rapid capacity decay and even heat deformation of the battery. In addition, if a short circuit fault occurs in the parallel connected battery, all the battery power in the parallel connection will pass through the short circuit battery, which may cause safety risks such as burning and explosion.

[0015] Both the above two traditional battery equalization circuits and energy storage systems have certain technical problems. In actual application, especially in lead-carbon battery systems, temperature and charging voltage do not match, which leads to a series of problems. The analysis is as follows:

[0016] Lead-carbon batteries (lead-acid batteries) will undergo oxidation and reduction reactions (electrochemical reactions) during charging and discharging. The reaction is greatly affected by temperature. The energy efficiency of the battery is about 80%-90%. Due to the large number of battery cells in the energy storage system and the large differences in heat conduction and heat dissipation caused by installation location, the temperature difference between the battery cells is large, generally above 4℃, and some even reach 15℃. During the charging process of the battery, the higher the temperature, the more intense the electrochemical reaction, that is, the larger the charging current, and the lower the temperature, the slower the electrochemical reaction, that is, the smaller the charging current. The main control of the traditional energy storage system equalization system is "voltage equalization", that is, the voltage of the battery is adjusted to be consistent, which is contrary to temperature compensation, and will cause the battery with high temperature to have a charging voltage that is too high, resulting in a large amount of overcharging, serious heating of the battery, and a large increase in the water loss rate of the battery, which greatly increases the possibility of thermal runaway of the battery, and even causes extreme safety accidents. On the contrary, the battery with low temperature will have a charging voltage that is too low, resulting in insufficient charging and causing faults such as sulfation, which leads to rapid decay of the battery. SUMMARY

[0017] In view of the above analysis, the embodiments of the present application aim to provide a battery temperature equalization control system and method to solve the problem that the voltage equalization of the traditional energy storage system adjusts the voltage of the battery to be consistent, which is contrary to temperature compensation, that is, the battery with high temperature has a charging voltage that is too high, resulting in a large amount of overcharging, serious heating of the battery, and a large increase in the water loss rate of the battery, which greatly increases the possibility of thermal runaway of the battery, and even causes extreme safety accidents. On the contrary, the battery with low temperature will have a charging voltage that is too low, resulting in insufficient charging and causing faults such as sulfation, which leads to rapid decay of the battery.

[0018] In one aspect, the embodiment of the present application provides a storage battery temperature equalization control system, comprising: a storage battery and an equalization circuit, wherein the storage battery comprises parallel battery groups, and the equalization circuit comprises: a plurality of diodes, the positive pole of each unit cell in the parallel battery group is connected to the anode of a diode in the plurality of diodes in series, and the cathode of the diode is connected to a first common node; a plurality of current limiting resistors, the negative pole of each unit cell in the parallel battery group is connected to one end of a current limiting resistor in the plurality of current limiting resistors in series, and the other end of the current limiting resistor is connected to a second common node; and an equalization resistor and an electronic switch, the equalization resistor and the electronic switch are connected in series, and then the series-connected equalization resistor and the electronic switch are connected between the first common node and the second common node.

[0019] The beneficial effects of the above technical solution are as follows: the storage battery charging process needs to be temperature compensated, that is, when the temperature of the storage battery rises, the charging voltage is reduced through the equalization circuit to avoid excessive charging current and cause a large amount of overcharging; and when the temperature of the storage battery decreases, the charging voltage is increased through the equalization circuit to charge enough, thereby avoiding undercharging.

[0020] Based on the further improvement of the above system, the storage battery temperature equalization control system further comprises a temperature sensor arranged at a fixed position of the unit cell for detecting the temperature value of the unit cell in real time, wherein the number of the temperature sensors is the same as the number of the unit cells, so that one temperature sensor is arranged at the fixed position of each unit cell.

[0021] Based on the further improvement of the above system, the fixed position comprises the upper surface of the unit cell, the side surface of the unit cell, or the positive and negative pole terminals of the unit cell.

[0022] Based on the further improvement of the above system, the storage battery comprises an array of m*n unit cells, n unit cells in each row of the array of unit cells are connected in series as a series battery group to obtain m series battery groups, and m unit cells in each column of the array of unit cells are connected in parallel as a parallel battery group to obtain n parallel battery groups, wherein m and n represent positive integers greater than 1.

[0023] Based on the further improvement of the above system, the storage battery temperature equalization control system further comprises a battery management system BMS for receiving temperature value data in a data line or wireless transmission mode, providing a switching instruction of the electronic switch to the corresponding electronic switch according to the temperature value data and the state of the unit cell, to control the discharging state or the stop state of the unit cell.

[0024] Based on the further improvement of the above system, the battery management system BMS includes a receiving module, a calculation module, a temperature comparison module, an instruction generation module and an instruction output module, wherein the receiving module is used to receive the temperature data of the unit battery from the temperature sensor; the calculation module is used to calculate the average temperature of the storage battery according to the temperature value of the unit battery; the temperature comparison module is used to compare the average temperature of the storage battery with the temperature reference value and provide the comparison result to the instruction generation module; the instruction generation module is used to transmit the electronic switch opening instruction to the instruction output module when the comparison result is that the temperature value of the unit battery is lower than the temperature reference value; and transmit the electronic switch closing instruction to the instruction output module when the comparison result is that the temperature value of the unit battery is higher than the temperature reference value; the instruction output module is used to output the electronic switch opening instruction or the electronic switch closing instruction and provide it to the corresponding electronic switch to control the opening or closing of the electronic switch according to the electronic switch opening instruction or the electronic switch closing instruction, thereby controlling the storage battery to be in the balanced discharge state or the stop balanced discharge state, so as to reduce the charging voltage of the storage battery through balanced discharge, and thereby reduce the temperature value of the unit battery.

[0025] Based on the further improvement of the above system, the storage battery temperature balancing control system further includes: a voltage sensor for detecting the voltage value of the parallel unit battery in real time and providing the storage battery voltage value to the receiving module; a current sensor for detecting the charging and discharging current of the parallel unit battery in real time and providing the charging and discharging current to the receiving module; the battery management system BMS further includes: a charging judgment module for judging the current charging stage of the storage battery according to the voltage value of the unit battery and the charging and discharging current, and thereby determining whether to perform temperature compensation calculation; wherein the calculation module is further used to calculate the total constant voltage charging voltage value according to the average temperature of the storage battery, the number of unit batteries in the parallel battery pack and the constant voltage charging voltage of the parallel battery pack under the condition of the temperature reference value.

[0026] Based on the further improvement of the above system, the charging judgment module is used to: when the storage battery voltage value is lower than the first charging voltage threshold, judge that the storage battery is in the first charging stage, wherein the charging process of the first charging stage is constant current limited voltage charging; when the storage battery voltage value is equal to the first charging voltage threshold and the charging time does not exceed the first time threshold, judge that the storage battery is in the second charging stage, wherein the charging process of the second charging stage is constant current constant voltage charging; when the storage battery voltage value is lower than the second charging voltage threshold and the charging time does not exceed the second time threshold, judge that the storage battery is in the third charging stage, wherein the charging process of the third charging stage is constant current constant voltage charging.

[0027] In another aspect, the embodiments of the present application provide a battery temperature equalization control method, comprising: receiving temperature value data of unit cells from temperature sensors; comparing the temperature value of the unit cells with a temperature reference value; transmitting an electronic switch opening instruction to the instruction output module when the temperature value of the unit cells is lower than the temperature reference value; transmitting an electronic switch closing instruction to the instruction output module when the temperature value of the unit cells is higher than the temperature reference value; and providing the electronic switch opening instruction or the electronic switch closing instruction to the corresponding electronic switch to control the electronic switch to open according to the electronic switch opening instruction or to close according to the electronic switch closing instruction, thereby controlling the discharge state or the stop state of the battery.

[0028] Based on the above method, further improvements include, before receiving temperature value data of unit cells from temperature sensors, connecting n unit cells in each row of the unit cell array in series to obtain m series-connected battery groups, and connecting m unit cells in each column of the unit cell array in parallel to obtain n parallel-connected battery groups, wherein the battery includes an m×n unit cell array, and m and n represent positive integers greater than 1; connecting the positive electrode of each unit cell in each parallel-connected battery group to the anode of one diode of a plurality of diodes, and connecting the cathode of the diode to a first common node; connecting the negative electrode of each unit cell in each parallel-connected battery group to one end of a current-limiting resistor of a plurality of current-limiting resistors, and connecting the other end of the current-limiting resistor to a second common node; and connecting the equalization resistor and the electronic switch in series, and then connecting the series-connected equalization resistor and the electronic switch between the first common node and the second common node, wherein the equalization circuit includes a plurality of diodes, a plurality of current-limiting resistors, an equalization resistor, and an electronic switch.

[0029] Based on the above method, further improvements include that the current-limiting resistor is used to equalize the voltage of each unit cell in the parallel-connected battery group through the current-limiting resistor when the equalization circuit is in a closed state, to control the state of charge of each unit cell, and wherein equalizing the voltage of each unit cell in the parallel-connected battery group through the current-limiting resistor further includes that when there is a unit cell in the parallel-connected battery group whose voltage is lower than that of other unit cells, the other unit cells charge the unit cell with the lower voltage through the current-limiting resistor; and when there is a unit cell in the parallel-connected battery group whose voltage is higher than that of other unit cells, the unit cell with the higher voltage charges the other unit cells through the current-limiting resistor.

[0030] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0031] 1. The battery charging process needs to be temperature compensated, that is, when the battery temperature rises, the charging voltage is lowered through the equalization circuit to avoid excessive charging current and cause a large amount of overcharging; and when the battery temperature decreases, the charging voltage is increased through the equalization circuit to be fully charged.

[0032] 2. The battery charging and discharging reaction is an electrochemical reaction, which belongs to the redox reaction. The difficulty of the reaction changes with temperature, the higher the temperature, the faster the reaction speed, and vice versa, the lower the temperature, the slower the reaction speed. Ultimately, it is manifested as a change in charging and discharging speed. Therefore, when the battery temperature is high, the discharge capacity is high, and when the temperature is low, the discharge capacity is low. When charging, temperature compensation is needed, that is, the battery temperature is high, the charging voltage should be lowered to avoid overcharging. When the battery temperature is low, the charging voltage should be increased to be fully charged.

[0033] 3. When the battery equalization circuit is in a closed state, the parallel batteries are equalized to be consistent through the current limiting resistor, which plays a "clamping" role, so that the battery with large capacity will output more power, and the battery with small capacity will output less power, realizing "more work for the able" and playing a "self-protection" function. As long as the voltage of the parallel battery is controlled well, the state of charge (soc state) of the battery can be well controlled to avoid overcharging and overdischarging. At the same time, due to the current limiting resistor, even if there is a micro-short circuit or short circuit fault battery in the parallel circuit, the current limiting resistor will limit the current to avoid the situation that other batteries output large current to the fault battery, avoiding safety accidents. Under normal circumstances, the battery difference will be "self-balanced" through the current limiting resistor.

[0034] In the present application, the above technical solutions can be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the detailed description. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0036] Figure 1 is a typical conventional energy storage battery management system;

[0037] Figure 2 and Figure 3Fig. 1 is a diagram of a battery management circuit (BMU) in a parallel-serial structure, where each parallel battery group has 2-n unit cells;

[0038] Figure 4 Fig. 2 is a diagram of a battery equalization circuit and a battery according to an embodiment of the present application;

[0039] Figure 5 Fig. 3 is a flow chart of a temperature equalization and charging voltage control method according to an embodiment of the present application.

[0040] Figure 6 Fig. 4 is a flow chart of a battery temperature equalization control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application will be described in detail below with reference to the drawings, in which the figures constitute a part of the present application and are used to explain the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0042] As shown in Fig. 1, one embodiment of the present application discloses a battery temperature equalization control system including a battery, an equalization circuit, a temperature sensor, a battery management system (BMS) and a power storage inverter system (PCS). Figure 4 Specifically, the battery includes an array of m x n unit cells, n unit cells in each row of the array of unit cells are connected in series to form a series battery group to obtain m series battery groups, and m unit cells in each column of the array of unit cells are connected in parallel to form a parallel battery group to obtain n parallel battery groups, where m and n represent positive integers greater than 1.

[0043] Specifically, the equalization circuit includes a plurality of diodes, a positive electrode of each unit cell in the parallel battery group is connected in series to an anode of one diode in the plurality of diodes, and a cathode of the diode is connected to a first common node; a plurality of current-limiting resistors, a negative electrode of each unit cell in the parallel battery group is connected in series to one end of one current-limiting resistor in the plurality of current-limiting resistors, and the other end of the current-limiting resistor is connected to a second common node; and an equalization resistor and an electronic switch, the equalization resistor and the electronic switch are connected in series, and the series-connected equalization resistor and electronic switch are connected between the first common node and the second common node.

[0044] The function of the diode is to ensure one-way discharge when the equalization circuit is working, and to avoid "circulating current" caused by voltage difference between the batteries.

[0045]

[0046] ​The function of the current limiting resistor is that if there is a low voltage battery in the parallel battery, other batteries will charge the low voltage battery through the current limiting resistor, and vice versa, if there is a high voltage battery in the parallel battery, it will charge other batteries, and play a role of "self-balancing" between the parallel batteries.

[0047] Each of the plurality of temperature sensors is arranged at a fixed position of a unit cell for real-time detection of a temperature value of the unit cell, wherein the number of temperature sensors is the same as the number of unit cells, so that each unit cell is provided with a temperature sensor at a fixed position. The fixed position can include the upper surface of the unit cell, the side surface of the unit cell, or the positive and negative terminals of the unit cell. For example, the ambient temperature is usually 20-30℃, the temperature of the unit cell is usually 20-35℃, and the temperature of the battery during charging will increase by 4-7℃.

[0048] The battery management system BMS is used to receive temperature value data in a data line (such as CAN bus) or wireless transmission mode, calculate the charging voltage value of the parallel unit cell according to the average temperature value data of the parallel unit cell, compare it with the actual detected parallel unit charging voltage, and if the voltage is higher than the calculated charging voltage value, an electronic open circuit instruction should be output, otherwise a stop discharging instruction should be output.

[0049] Each of the plurality of temperature sensors is used for real-time detection of the temperature of a unit cell. The voltage sensor is used for real-time detection of the voltage value of the parallel unit cell and provides the voltage value of the parallel unit cell to the receiving module. The current sensor is used for real-time detection of the charging and discharging current of the parallel unit cell and provides the charging and discharging current to the receiving module.

[0050] The battery management system BMS includes a receiving module, a calculation module, a temperature comparison module, an instruction generation module, a charging judgment module and an instruction output module. The receiving module is used to receive the temperature data of the unit cell from the temperature sensor. The calculation module is used to calculate the average temperature of the battery according to the temperature value of the unit cell. The temperature comparison module is used to compare the average temperature of the battery with the temperature reference value and provide the comparison result to the instruction generation module. The instruction generation module is used to transmit the electronic switch opening instruction to the instruction output module when the comparison result is that the temperature value of the unit cell is lower than the temperature reference value (such as 25℃); otherwise, when the comparison result is that the temperature value of the unit cell is higher than the temperature reference value (such as 25℃), the electronic switch closing instruction is transmitted to the instruction output module. The instruction output module is used to output the electronic switch opening instruction or the electronic switch closing instruction and provide it to the corresponding electronic switch to control the opening or closing of the electronic switch according to the electronic switch opening instruction or the electronic switch closing instruction, and then control the battery to be in the balanced discharging state or the stop balanced discharging state, so as to reduce the charging voltage of the battery through balanced discharging, and then reduce the temperature value of the unit cell.

[0051] In addition, the battery management system BMS further comprises a charging judgment module configured to determine a current charging stage of the storage battery according to the voltage value of the unit battery and the charging and discharging current, and further determine whether to perform temperature compensation calculation. The calculation module is further configured to calculate a total constant voltage charging voltage value according to the average temperature of the storage battery, the number of unit batteries in the parallel battery group, and the constant voltage charging voltage of the parallel battery group under the condition of the temperature reference value. The energy storage inverter system PCS is configured to start the rectifier device or the inverter device according to the current charging stage and / or the total constant voltage charging voltage value.

[0052] The BMS calculates the average temperature of the entire storage battery group according to the storage battery temperature data, and calculates the total constant voltage charging voltage value Uconstant of the PCS output according to the following formula.

[0053] Uconstant = n x 2.45v + 0.003v x (25-Taverage)

[0054] Wherein, Uconstant is the total constant voltage charging voltage of the PCS output, unit v; Taverage is the average temperature of the storage battery group, unit ℃; n is the number of parallel battery groups; 2.45v is the constant voltage charging voltage of the parallel battery at 25℃.

[0055] The role of the battery management system (BMS) is to monitor the charging and discharging current I of the parallel storage battery, the voltage v of the parallel unit battery, and the temperature T of the storage battery. Each storage battery in each parallel circuit has a temperature sensor, and the storage battery temperature is transmitted to the BMS. The BMS calculates the average temperature of each parallel group of storage batteries, and judges whether the temperature exceeds the specified temperature. If so, the BMS will issue a closing equalization circuit switch instruction P to perform equalization discharge, so as to reduce the charging voltage of the storage battery and achieve the effect of reducing the temperature of the storage battery. Otherwise, the BMS will issue an opening equalization circuit switch instruction O.

[0056] Specifically, the charging judgment module is configured to: when the voltage value of the storage battery is lower than a first charging voltage threshold (for example, 2.45V in Table 1), determine that the storage battery is in a first charging stage, wherein the charging process of the first charging stage is constant current limited voltage charging; when the voltage value of the storage battery is equal to the first charging voltage threshold and the charging time does not exceed a first time threshold (for example, 120min in Table 1), determine that the storage battery is in a second charging stage, wherein the charging process of the second charging stage is constant current constant voltage charging; when the voltage value of the storage battery is lower than a second charging voltage threshold (for example, 2.55V in Table 1) and the charging time does not exceed a second time threshold (for example, 90min in Table 1), determine that the storage battery is in a third charging stage, wherein the charging process of the third charging stage is constant current constant voltage charging.

[0057] Example 1: Charging indicators at 25℃

[0058] Table 1: Battery charging technical requirements at 25°C

[0059]

[0060] Example 2: Charging indicators at 15°C

[0061] Battery charging technical requirements at 15°C

[0062]

[0063] Example 3: Charging indicators at 35°C

[0064] Battery charging technical requirements at 35°C

[0065]

[0066] The charging of the energy storage system is divided into three types: partial charging, floating charging and full charging.

[0067] (1) Partial charging: emergency charging after battery discharge, which is incomplete charging, and all or part of the process in the 1-2 step sequence charging process in Table 2 above;

[0068] (2) Floating charging: charging after the battery is charged to step 4, which is generally charging within 1-3 times in Table 2 above, and constant current limited voltage charging is used under sufficient time, and about 1% of the battery capacity is charged;

[0069] (3) Full charging: after the battery is used for a number of cycles (the number of times can be adjusted according to the actual situation), a full charging is needed, which is an additional equalization charging stage after the completion of the partial charging process;

[0070] (4) Equalization charging: constant current limited voltage charging is used, according to step 4 in Table 2 above, about 2% of the battery capacity is charged, and the purpose is to compensate for the inconsistency caused by the charging efficiency or self-discharge of the battery, and to take equalization charging.

[0071] Compared with the prior art, the battery temperature equalization control system provided by the embodiment needs to be temperature compensated in the charging process, that is, when the battery temperature rises, the charging voltage is reduced through the self-balancing effect of the equalization circuit, and then the battery temperature value is reduced, so as to avoid excessive charging current and cause a large amount of overcharging; when the battery temperature is reduced, the charging voltage is increased through the self-balancing effect of the equalization circuit, and then the battery temperature value is increased, so as to be fully charged. Specifically, if the voltage of a battery in the parallel battery is low, the other batteries will charge the low-voltage battery through the current-limiting resistor, and vice versa, if the voltage of a battery in the parallel battery is high, the other batteries will be charged, thereby playing a "self-balancing" role between the parallel batteries. When the battery equalization circuit is in a closed state, the parallel batteries are balanced to be consistent through the current-limiting resistor, thereby playing a "clamping" role, so that the battery with large capacity will output more power, and the battery with small capacity will output less power, thereby realizing "more work for the able" and playing a "self-protection" function.

[0072] Reference Figure 6 Another specific embodiment of the present application discloses a battery temperature equalization control method, comprising:

[0073] The n unit cells in each row of the unit cell array are connected in series to obtain m series battery groups, and the m unit cells in each column of the unit cell array are connected in parallel to obtain n parallel battery groups, wherein the battery comprises m*n unit cell arrays, and m and n represent positive integers greater than 1.

[0074] The positive electrode of each unit cell in each parallel battery group is connected in series to the anode of one of the plurality of diodes, and the cathode of the diode is connected to the first common node.

[0075] The negative electrode of each unit cell in each parallel battery group is connected in series to one end of one of the plurality of current-limiting resistors, and the other end of the current-limiting resistor is connected to the second common node.

[0076] The equalization resistor and the electronic switch are connected in series, and then the series-connected equalization resistor and the electronic switch are connected between the first common node and the second common node, wherein the equalization circuit comprises a plurality of diodes, a plurality of current-limiting resistors, an equalization resistor, and an electronic switch.

[0077] In step S601, temperature value data of the unit cell is received from the temperature sensor.

[0078] In step S602, the temperature value of the unit cell is compared with a temperature reference value.

[0079] In step S603, when the temperature value of the unit battery is lower than the temperature reference value, the electronic switch opening instruction is transmitted to the instruction output module; when the temperature value of the unit battery is higher than the temperature reference value, the electronic switch closing instruction is transmitted to the instruction output module.

[0080] In step S604, the electronic switch opening instruction or the electronic switch closing instruction is provided to the corresponding electronic switch to control the electronic switch to open or close according to the electronic switch opening instruction or the electronic switch closing instruction, thereby controlling the discharge state or the stop state of the storage battery.

[0081] The current limiting resistor is used to equalize the voltage of each unit battery in the parallel battery pack through the current limiting resistor when the equalization circuit is in the closed state, to control the state of charge of each unit battery, wherein the equalization of the voltage of each unit battery in the parallel battery pack through the current limiting resistor further comprises: when there is a unit battery with a voltage lower than that of other unit batteries in the parallel battery pack, the other unit batteries charge the unit battery with the lower voltage through the current limiting resistor; and when there is a unit battery with a voltage higher than that of other unit batteries in the parallel battery pack, the unit battery with the higher voltage charges the other unit batteries through the current limiting resistor.

[0082] Hereinafter, the storage battery temperature equalization control system according to the embodiment of the present application is described in detail in the form of specific examples with reference to Figure 4 and Figure 5 .

[0083] The present application is a new parallel and series mode and temperature equalization control circuit, and a control strategy.

[0084] In Figure 4 and Figure 5 , it is a new parallel and series mode and temperature control circuit, and a control strategy diagram. The main loop is n storage batteries in series, and there are m parallel paths in total. Each storage battery can be 1-x single cells in series inside.

[0085] (1) The first parallel unit cell B1-1, B1-2 …… B1-m, the positive electrode is connected to a diode D1-1, D1-2 …… D1-m, respectively, converged at a point A1, the negative electrode is connected to a current-limiting resistor r1-1, r1-2 …… r1-m, respectively, converged at a point B1, A1 point B1 point between a balancing resistor R1 and electronic switch K1 (relay, etc.), forming a balancing circuit. When the electronic switch K1 is closed, the balancing circuit is in a discharge state, that is, the parallel battery B1-1, B1-2 …… B1-m, simultaneously discharged. And when the electronic switch K1 is open, the discharge stops. The fixed point of the battery B1-1, B1-2 …… B1-m is provided with a temperature sensor T1-1, T1-2 …… T1-m (thermistor or temperature sensor, etc.), and its temperature data is transmitted to the BMS (i.e., the "complete system" of battery management, including hardware and software, responsible for the global management of the battery pack, covering safety protection, state estimation, balancing control, communication scheduling, etc.) in a certain form (data line or wireless transmission, etc.), and the BMS will issue the switching command of the electronic switch K1 according to the temperature of the battery and the state of the battery, control the switching state of K1, and also control the discharge and stop state of the battery. When the battery main circuit is in a charging state, the battery temperature value exceeds the normal temperature value of the battery, and the BMS will issue the closing command of K1, and the battery B1-1, B1-2 …… B1-m is in a balanced discharge state, and when the battery temperature value is lower than the normal temperature value of the battery, the electronic switch is in an open state, and the battery balancing circuit is in a non-discharge state. When the battery main circuit is in a discharge state, the electronic switch is in an open state, and the battery balancing circuit is in a non-discharge state.

[0086] (2) Second parallel unit cell B2-1, B2-2 …… B2-m, the positive pole is connected with a diode D2-1, D2-2 …… D2-m respectively, converging in a point A2, the negative pole is connected with a current-limiting resistor r2-1, r2-2 …… r2-m respectively, converging in a point B2, an equalizing resistor R2 and an electronic switch K2 (relay, etc.) are connected between A2 and B2, forming an equalizing circuit. When the electronic switch is closed, the equalizing circuit is in a discharging state, that is, the parallel battery B2-1, B2-2 …… B2-m is discharged at the same time. While when the electronic switch K2 is in the open state, the discharge stops. The fixed point of the battery B2-1, B2-2 …… B2-m is provided with a temperature sensor T2-1, T2-2 …… T2-m (thermistor or temperature sensor, etc.), and the temperature data is transmitted to the BMS in a certain form (data line or wireless transmission, etc.). The BMS will issue the switching command of the electronic switch K2 according to the temperature of the battery and the state of the battery, control the switching state of the electronic switch K2, and also control the discharge and stop state of the battery. When the battery main circuit is in a charging state, the battery temperature value exceeds the normal temperature value of the battery, and the BMS will issue the closing command of K2, and the battery B2-1, B2-2 …… B2-m is in the equalizing discharge state. When the battery temperature value is lower than the normal temperature value of the battery, the electronic switch is in the open state, and the battery equalizing circuit is in the non-discharge state. When the battery main circuit is in a discharging state, the electronic switch is in the open state, and the battery equalizing circuit is in the non-discharge state.

[0087] (3) The nth parallel unit cell Bn-1, Bn-2, …, Bn-m, the positive electrode is connected to a diode D3-1, D3-2, …, Dn-m, respectively, and converges at a point An, the negative electrode is connected to a current-limiting resistor r3-1, r3-2, rn-m, respectively, and converges at a point Bn, and an equalization resistor Rn and an electronic switch Kn (relay, etc.) are connected between the points An and Bn, forming an equalization circuit. When the electronic switch is closed, the equalization circuit is in a discharging state, that is, the parallel batteries Bn-1, Bn-2, …, Bn-m are discharged simultaneously. When the electronic switch Kn is open, the discharging stops. The fixed point of the storage battery Bn-1, Bn-2, …, Bn-m is provided with a temperature sensor Tn-1, Tn-2, …, Tn-m (thermistor or temperature sensor, etc.), and the temperature data is transmitted to the BMS in a certain form (data line or wireless transmission, etc.). The BMS will issue a switching command for the electronic switch Kn according to the temperature of the storage battery and the state of the storage battery, control the switching state of Kn, and control the discharging and stopping state of the battery. When the main circuit of the storage battery is in a charging state, the temperature value of the storage battery exceeds the normal temperature value of the storage battery, and the BMS will issue a closing command for the Kn, and the storage battery Bn-1, Bn-2, …, Bn-m is in an equalization discharging state. When the temperature value of the storage battery is lower than the normal temperature value of the storage battery, the electronic switch is in an open state, and the equalization circuit of the storage battery is in a non-discharging state. When the main circuit of the storage battery is in a discharging state, the electronic switch is in an open state, and the equalization circuit of the storage battery is in a non-discharging state.

[0088] (4) As in Figure 4 and Figure 5 , the first parallel is taken as an example to explain the principle of battery self-balancing: when the battery equalization circuit is in an open state, the negative electrode is connected to a current-limiting resistor r1-1, r1-2, …, r1-m, respectively, and converges at a point B1. If there is a battery with low voltage in the parallel storage battery, the other batteries will charge the low-voltage battery through the current-limiting resistor, and vice versa. If there is a battery with high voltage in the parallel battery, it will charge the other batteries, achieving the function of "self-balancing" between parallel batteries. When the battery equalization circuit is in a closed state, the voltage of the parallel battery is balanced to be consistent through the current-limiting resistor, achieving the function of "clamping", so that the battery with large capacity will output more power, and the battery with small capacity will output less power, achieving the function of "self-protection". As long as the voltage of the parallel battery is controlled well, the state of charge (soc state) of the battery can be well controlled, avoiding overcharging and overdischarging. At the same time, due to the current-limiting resistor, even if there is a fault battery with micro-short circuit or short circuit in the parallel circuit, the current-limiting resistor will limit the current, avoiding the situation that other batteries output large current to the fault battery, avoiding safety accidents, and in normal circumstances, the battery difference will be "self-balanced" through the current-limiting resistor.

[0089] The battery charging and discharging reaction is an electrochemical reaction, which belongs to the redox reaction. The ease of reaction changes with temperature, the higher the temperature, the faster the reaction speed, and vice versa, the lower the temperature, the slower the reaction speed. Ultimately, it is manifested as a change in the charging and discharging speed. Therefore, when the battery temperature is high, the discharge capacity is high, and when the temperature is low, the discharge capacity is low. When charging, temperature compensation is required, that is, when the battery temperature is high, the charging voltage should be lowered to avoid overcharging. When the battery temperature is low, the charging voltage should be increased to fully charge the battery.

[0090] Lead-carbon battery temperature equalization control and energy storage system: the main loop is 24 2V 50Ah batteries in series, a total of 4 parallel paths. Each battery can be a single cell in series inside. The battery pack is a 48V 200Ah battery pack.

[0091] The first parallel unit cell B1-1, B1-2, B1-3, B1-4, the positive electrode is connected to one 1N4007 diode, respectively, and converges at point A1. The negative electrode is connected to one 0.1Ω 0.5w current limiting resistor, respectively, and converges at B1. A 1.5Ω 5w equalization resistor and an electronic switch K1 (relay, etc.) are connected between A1 and B1, forming an equalization circuit. When the electronic switch is closed, the equalization circuit is in a discharging state, that is, the parallel batteries B1-1, B1-2, B1-3, B1-4 are discharging at the same time, and the discharging current is about 1.0-1.2A. When the electronic switch K1 is open, the discharging stops. The fixed point of the battery B1-1, B1-2, B1-3, B1-4 is provided with a temperature sensor T1-1, T1-2, T1-3, T1-4 (thermistor or temperature sensor, etc.), and the temperature data is transmitted to the BMS through CAN. The BMS will issue a switching command for the electronic switch K1 according to the battery temperature and the state of the battery, control the switching state of K1, and control the discharging and stopping state of the battery. When the battery main loop is in the charging state, it is determined to be the second stage of charging (see battery charging technical requirements), and the battery temperature reference value is set to 25℃. When the temperature value exceeds 30℃, the BMS will issue a closing command for K1, and the batteries B1-1, B1-2, B1-3, B1-4 are in an equalization discharging state, and the battery voltage will gradually decrease. When the battery voltage drops to the required battery voltage value: 2.45v+0.003v×(25-30)=2.435V, the temperature will also gradually decrease. When the battery temperature is lower than 25℃, the electronic switch is in an open state, and the battery equalization circuit is in a non-discharging state. When the battery main loop is in a discharging state, the electronic switch is in an open state, and the battery equalization circuit is in a non-discharging state, which plays a role in controlling the temperature of the battery.

[0092] The function of the battery management system (BMS) is to monitor the charge and discharge current I of the parallel battery, the voltage v of the parallel unit battery, and the temperature T of the battery. The PCS charges and discharges the battery according to the project energy storage requirements and the battery charge and discharge regulations. The battery judges the detected battery temperature during the charging process. If the temperature exceeds the specified temperature, the closing balance circuit switch instruction P will be issued to perform the balance discharge to reduce the battery charging voltage and achieve the effect of reducing the battery temperature. Otherwise, the opening balance circuit switch instruction O will be issued.

[0093] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing relevant hardware, and the program can be stored in a computer readable storage medium. The computer readable storage medium includes a magnetic disk, an optical disk, a read-only memory, a random access memory, etc.

[0094] The above description is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art, and should be covered within the protection scope of the present application.

Claims

1. A battery temperature equalization control system, characterized in that, include: A storage battery and an equalization circuit, wherein the storage battery includes a parallel battery pack, and the equalization circuit includes: Multiple diodes, wherein the positive terminal of each cell in the parallel battery pack is connected in series to the anode of one of the multiple diodes, and the cathode of the diode is connected to a first common node; Multiple current-limiting resistors are provided, wherein the negative terminal of each cell in the parallel battery pack is connected in series to one end of one of the multiple current-limiting resistors, and the other end of the current-limiting resistor is connected to a second common node; and A balancing resistor and an electronic switch are connected in series, and the series-connected balancing resistor and electronic switch are connected between the first common node and the second common node.

2. The battery temperature equalization control system according to claim 1, characterized in that, It also includes a temperature sensor, which is set at a fixed position of the cell battery to detect the temperature value of the cell battery in real time. The number of temperature sensors is the same as the number of cell batteries, so that one temperature sensor is set at a fixed position of each cell battery.

3. The battery temperature equalization control system according to claim 2, characterized in that, The fixed position includes the upper surface of the cell, the side of the cell, or the positive and negative terminals of the cell.

4. The battery temperature equalization control system according to claim 1, characterized in that, The battery comprises an array of m×n cell units. Connect n individual cells in each row of the cell array in series to form a series battery pack to obtain m series battery packs; as well as m cells in each cell array are connected in parallel to form a parallel battery pack to obtain n parallel battery packs, where m and n represent positive integers greater than 1.

5. The battery temperature equalization control system according to claim 2, characterized in that, It also includes a battery management system (BMS) for receiving temperature data via data cable or wireless transmission, and providing switching commands to the corresponding electronic switches based on the temperature data and the state of the unit battery, in order to control the discharge state or stop state of the unit battery.

6. The battery temperature equalization control system according to claim 5, characterized in that, The battery management system (BMS) includes a receiving module, a calculation module, a temperature comparison module, an instruction generation module, and an instruction output module. The receiving module is used to receive temperature data of the cell battery from the temperature sensor; The calculation module is used to calculate the average temperature of the battery based on the temperature value of the unit cell. The temperature comparison module is used to compare the average temperature of the battery with a temperature reference value and provide the comparison result to the instruction generation module. The instruction generation module is used to transmit an electronic switch disconnect instruction to the instruction output module when the comparison result is that the temperature value of the cell is lower than the temperature reference value; and to transmit an electronic switch close instruction to the instruction output module when the comparison result is that the temperature value of the cell is higher than the temperature reference value. The instruction output module is used to output the electronic switch disconnection instruction or the electronic switch closing instruction and provide it to the corresponding electronic switch to control the electronic switch to disconnect or close according to the electronic switch disconnection instruction or the electronic switch closing instruction, thereby controlling the battery to be in a balanced discharge state or to stop the balanced discharge state, so as to reduce the charging voltage of the battery through balanced discharge, thereby reducing the temperature value of the cell.

7. The battery temperature equalization control system according to claim 6, characterized in that, Also includes: A voltage sensor is used to detect the voltage value of the parallel-connected unit batteries in real time and provide the battery voltage value to the receiving module; A current sensor is used to detect the charging and discharging current of the parallel-connected unit batteries in real time and provide the charging and discharging current to the receiving module. The battery management system (BMS) further includes a charging judgment module, used to determine the current charging stage of the battery based on the voltage value of the unit cell and the charging / discharging current, and then determine whether to perform temperature compensation calculation; wherein, the calculation module is also used to calculate the total constant voltage charging voltage value based on the average temperature of the battery, the number of unit cells in the parallel battery pack, and the constant voltage charging voltage of the parallel battery pack under the temperature reference value condition.

8. The battery temperature equalization control system according to claim 7, characterized in that, The charging determination module is used for: When the battery voltage is lower than the first charging voltage threshold, the battery is determined to be in the first charging stage, wherein the charging process in the first charging stage is constant current voltage limiting charging. When the battery voltage value is equal to the first charging voltage threshold and the charging time does not exceed the first time threshold, the battery is determined to be in the second charging stage, wherein the charging process of the second charging stage is constant current constant voltage charging. When the battery voltage is lower than the second charging voltage threshold and the charging time does not exceed the second time threshold, the battery is determined to be in the third charging stage, wherein the charging process of the third charging stage is constant current and constant voltage charging.

9. A battery temperature equalization control method, based on the battery temperature equalization control system according to any one of claims 1-8, characterized in that, include: Receive temperature data of the cell unit from the temperature sensor; The temperature value of the cell unit is compared with the temperature reference value; When the temperature of the cell is lower than the temperature reference value, the electronic switch disconnection command is transmitted to the command output module. When the temperature of the cell is higher than the temperature reference value, an electronic switch closing command is transmitted to the command output module; The electronic switch is given a disconnect command or an electronic switch is given a corresponding electronic switch to control the electronic switch to disconnect or close according to the electronic switch disconnect command, thereby controlling the discharge state or stop state of the battery.

10. The battery temperature equalization control method according to claim 9, characterized in that, When the equalization circuit is in the closed state, the voltage of each cell in the parallel battery pack is equalized by the current-limiting resistor to control the state of charge of each cell. The equalization of the voltage of each cell in the parallel battery pack by the current-limiting resistor further includes: When the voltage of one cell in the parallel battery pack is lower than the voltage of the other cells, the other cells charge the cell with the lower voltage through the current-limiting resistor; and When the voltage of a cell in the parallel battery pack is higher than that of the other cells, the cell with the higher voltage charges the other cells through the current-limiting resistor.

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