A thermal management system for a battery cabinet and a control method thereof

Abstract

The application provides a battery cabinet heat management system and a control method thereof. The battery cabinet heat management system comprises a cooling system, a control unit and a simulation unit. The cooling system comprises a cooling main pipe for injecting coolant, a plurality of injection branch pipes corresponding to each battery module and a plurality of backwater branch pipes. The simulation unit gives a simulated battery module average temperature trend curve and a battery module average temperature rise rate trend curve based on the measured battery module ambient temperature, the battery module capacity attenuation rate and the battery module operating condition. The control unit controls the flow of the main pipe flow valve on the injection main pipe and the coolant temperature based on the measured battery module average temperature of the plurality of batteries, the simulated battery module average temperature trend curve and the battery module average temperature rise rate trend curve. The control unit controls the flow of the branch pipe flow valve on each injection branch pipe based on the temperature detected by the temperature sensor on each backwater branch pipe.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium battery, in particular to a battery cabinet heat management system and a control method thereof. BACKGROUND

[0002] Lithium ion battery is a new type of high-energy battery with lithium intercalation compound as positive and negative electrode material. Compared with lead-acid battery and nickel-hydrogen battery, it has a series of advantages such as high specific energy, high voltage, small self-discharge, good cycle performance and long service life, and is more and more concerned by people, and is widely used in energy storage field. The heat management of energy storage lithium battery is a necessary condition to ensure the safe operation of the system. The convective heat transfer coefficient of liquid cooling system is about 10 times that of forced air cooling, which has more efficient heat dissipation, can reduce equipment noise and energy consumption, and has become one of the most common heat management methods of current energy storage system. The control strategy of the existing liquid cooling heat management system of energy storage is generally to detect the medium temperature and pressure on the total circuit to adjust the unit cooler or flow pump. Since the energy storage system is composed of multiple battery modules, in order to ensure the uniformity of the temperature distribution of the whole system, the modules at different positions need more refined adjustment control. SUMMARY

[0003] In view of the above problems, the present application provides a battery cabinet heat management system and a control method thereof. The battery cabinet heat management system comprises a cooling system, a control unit and a simulation unit. The cooling system comprises a cooling main pipe for injecting coolant, a plurality of injection branch pipes corresponding to each battery module, and a plurality of return water branch pipes. The simulation unit gives the simulated battery module average temperature trend curve and the battery module average temperature rise rate trend curve based on the measured battery module environment temperature, the battery module capacity attenuation rate and the battery module operating condition. The control unit controls the flow and the coolant temperature of the total pipe flow valve on the injection main pipe based on the measured battery module average temperature of the plurality of batteries, the simulated battery module average temperature trend curve and the battery module average temperature rise rate trend curve. The control unit controls the flow of the branch pipe flow valve on each injection branch pipe based on the temperature detected by the temperature sensor on each return water branch pipe. Through the battery cabinet heat management system and the control method thereof, the whole battery system can be accurately and quickly temperature regulated, and the modules at different positions can be more finely temperature regulated and controlled, so as to ensure the uniformity of the temperature distribution of the whole system.

[0004] The technical scheme provided by the present application is as follows:

[0005] This invention provides a thermal management system for a battery cabinet. The battery cabinet contains multiple battery modules, temperature sensors for measuring the ambient temperature of the battery modules, and a battery management system. The thermal management system includes a cooling system, a control unit, and a simulation unit. The cooling system includes multiple injection branch pipes, multiple return branch pipes, and a main injection pipe. The injection branch pipes are connected to the battery modules respectively to inject coolant into them, and the return branch pipes are connected to the battery modules respectively to discharge the cooled coolant from them. Branch pipe flow valves are installed on the injection branch pipes to control the coolant flow rate, temperature sensors are installed on the return branch pipes to detect the return water temperature, and a main injection pipe flow valve is installed on the main injection pipe to control the coolant flow rate. The simulation unit is a simulation database that obtains the simulated average battery module temperature T based on the measured ambient temperature of the battery modules, the measured capacity decay rate of the battery modules, and the operating conditions of the battery modules. m Trend curve and simulated average temperature rise rate V of battery module m Trend curve. The control unit is based on the measured average temperature T of the battery module. r The simulated average temperature T of the battery module m Trend curve and simulated average temperature rise rate V of battery module m The curve controls the flow rate and coolant temperature of the main pipe flow valve on the main injection pipe, and the control unit controls the flow rate of the corresponding branch pipe flow valve on the injection branch pipe according to the temperature of the temperature sensor on the return branch pipe.

[0006] In other words, finite element simulation software such as Comsol and Matlab are used as simulation units for the thermal management system. Within the simulation system, the lumped parameter model is fitted and optimized using battery charge-discharge curves. A degradation factor is introduced to describe the relationship between battery capacity decay and ohmic internal resistance changes with the number of cycles. A simulation database is established, and corresponding average battery module temperatures T are generated based on different battery module ambient temperatures, battery module capacity decay rates, and battery module operating conditions. m Trend data and average temperature rise rate of battery module V m Trend data is used to obtain various battery module ambient temperatures, battery module capacity degradation rates, and battery module operating conditions, along with the corresponding average battery module temperature T. m Trend data and average temperature rise rate of battery module V m A database of trend data. During use, based on this simulation database and the measured ambient temperature, capacity degradation rate, and operating conditions of multiple battery modules, the simulated average temperature T of the battery module can be obtained. m Trend data and simulated average temperature rise rate V of battery modules mTrend data. According to the current time measurement, the simulation unit can predict the average temperature and temperature rise rate of the next moment, and then adjust the thermal management system in advance. In this way, it is not necessary to wait until the unevenness between the battery modules is measured to adjust the temperature, but the average temperature and temperature rise rate of the next moment can be predicted according to the simulation results, and the temperature can be controlled in advance, so that the thermal management system can be adjusted with prediction and pertinence. Among them, the battery module environment temperature can be measured by the temperature sensor arranged near or on the outer surface of the battery module, the battery module capacity attenuation rate can be obtained by measuring SOH through the battery management system, and the battery module operating condition can include charge-discharge rate, charge-discharge mode, etc.

[0007] The control unit controls the manifold flow valve on the injection manifold and the temperature of the refrigerant based on the battery module average temperature T m Trend curve and battery module average temperature rise rate V m The trend curve can quickly and accurately control the manifold flow valve on the injection manifold and the temperature of the refrigerant, thereby achieving effective control of the overall temperature of the battery system. The control unit can also control the branch flow valve on the injection branch corresponding to the return water branch based on the measured return water temperature of each return water branch, thereby achieving fine adjustment of the temperature of each battery module.

[0008] A heating module can also be provided on the injection branch, and the control unit can control the heating module to heat the coolant in the injection branch. When the return water temperature of a certain battery module is lower than the average return water temperature, the heating module on the injection branch corresponding to the battery module can be heated, so that the return water temperature of the battery module can quickly reach the average return water temperature, and the temperature of each battery module can be balanced. In addition, in a relatively cold region, due to the low temperature of the coolant input pipeline and the coolant, the start of the cooling system is difficult. By providing a heating module on the injection branch, the cooling system of the battery system can be quickly started, and the normal operation of the battery system can be ensured. The coolant in the pipeline of the cooling system can be liquid or gas. That is, unlike the traditional air cooling, gas can also be input into the pipeline as a coolant.

[0009] The application also provides a control method of the thermal management system of the battery cabinet as described above, which comprises the following steps:

[0010] (1) Monitor the battery module environment temperature, the battery module capacity attenuation rate and the battery module operating condition of each battery module, input the measured battery module environment temperature, the measured battery module capacity attenuation rate and the battery module operating condition into the simulation unit to obtain the simulated battery module average temperature T m Trend curve and simulated battery module average temperature rise rate V m Trend curve;

[0011] (2) Monitor the battery module temperature of each battery module, and the control unit takes the average of the temperatures of multiple battery modules to obtain the measured average battery module temperature T. r The simulated average temperature T of the current battery module m Compared with the measured average temperature T of the battery module r For comparison, if δT≤3℃, then the measured average temperature T of the battery module shall be used. r The simulated average temperature T of the battery module m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the main pipe flow valve on the injection main pipe and the temperature of the coolant in the injection main pipe, so that the average temperature T of the battery module is reduced. r The temperature should be between 25 and 40℃; if δT > 3℃, then the average temperature T of the battery module should be used as the actual measured temperature. r The simulated average temperature T of the battery module m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the main pipe flow valve on the main pipe and the temperature of the coolant in the main pipe, and issues a system warning signal;

[0012] (3) Monitor the return water temperature T of each return water branch pipe. hn The control unit averages multiple return water temperatures to obtain the average return water temperature T. ha The return water temperature T of each return water branch pipe hn With average return water temperature T ha Compare, if T hn > T ha If T, then increase the flow rate of the corresponding branch flow valve on the injection branch. hn < T ha If so, reduce the flow rate of the branch flow valve on the corresponding injection branch; or, install a heating module on the injection branch, if T hn < T ha The coolant in the injection branch pipe is heated by the heating module on the corresponding injection branch pipe.

[0013] In step (2), the actual battery module temperature can be measured by the battery management system. The simulated average battery module temperature T... m The current average temperature T of the battery module in the trend curve m Compared with the measured average temperature T of the battery module r If the difference δT ≤ 3℃, it indicates that the simulated numerical results are accurate, and this can be verified by the simulated average temperature T of the battery module. m Trend curve and simulated average temperature rise rate V of battery module mThe trend curve adjusts the cooling system. If the difference between the simulated battery module average temperature T m the current battery module average temperature T m measured and the simulated battery module average temperature T r is greater than 3℃, it indicates that the simulation result deviates from the measured result, and the cooling system can be adjusted according to the trend curve and the simulated battery module average temperature rise rate V m the trend curve and the simulated battery module average temperature rise rate V m the trend curve adjusts the cooling system, but at the same time, a warning signal is sent, so that each unit of the thermal management system can be checked in time, and problems can be quickly ruled out.

[0014] The advantages of the present application are:

[0015] 1) The battery modules in different positions can be more finely adjusted and controlled to ensure the uniformity of the temperature distribution of the entire battery system.

[0016] 2) The temperature and temperature rise rate at the next moment can be predicted according to the simulation result, the temperature can be controlled in advance, the thermal management system can be adjusted with prediction and pertinence, and adjustment lag can be prevented, so that the temperature uniformity of the entire energy storage battery system can be better controlled. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the thermal management system of the battery cabinet according to the present application;

[0018] Figure 2 is a logic diagram of the control method of the thermal management system of the battery cabinet according to the present application.

[0019] LIST OF REFERENCE NUMBERS:

[0020] 1 - battery cabinet

[0021] 101 - battery module

[0022] 201 - injection branch pipe

[0023] 202 - return water branch pipe

[0024] 203 - injection main pipe

[0025] 204 - heat exchange device

[0026] 205 - branch pipe flow valve

[0027] 206 - heating module

[0028] 207 - temperature sensor

[0029] 208 - main pipe flow valve

[0030] 3 - control unit

[0031] 4 - simulation unit DETAILED DESCRIPTION

[0032] The application will be further described by examples with reference to the accompanying drawings.

[0033] Figure 1 Fig. 1 is a schematic view of a thermal management system for a battery cabinet according to the present application. As shown in Fig. 1, a plurality of battery modules 101 are placed in the battery cabinet 1, and the battery cabinet 1 is also provided with temperature sensors for measuring the ambient temperature of the battery modules and a battery management system for receiving signals and issuing system control. Figure 1 The thermal management system for the battery cabinet comprises a cooling system, a control unit 3 and a simulation unit 4.

[0034] The cooling system is used for cooling the battery modules and can also be used for heating the battery modules, and comprises a plurality of injection branch pipes 201, a plurality of return branch pipes 202 and an injection main pipe 203. The plurality of injection branch pipes 201 are respectively connected to the plurality of battery modules 101 for respectively injecting coolant into the plurality of battery modules, and the plurality of return branch pipes 202 are respectively connected to the plurality of battery modules 101 for respectively discharging the coolant after heat exchange from the plurality of battery modules. The discharged coolant is cooled by a heat exchange device 204 and then circulated into the battery modules via the injection branch pipes 201 to cool the battery modules. A branch pipe flow valve 205 for controlling the flow of the coolant and a heating module 206 for heating the coolant are provided on each injection branch pipe 201, and a temperature sensor 207 for detecting the return water temperature is provided on each return branch pipe 202, and a main pipe flow valve 208 for controlling the flow of the coolant is provided on the injection main pipe 203.

[0035] The simulation unit 4 is a simulation database, which gives a simulated average temperature T m of the battery modules and a simulated average temperature rise rate V m of the battery modules based on the input measured ambient temperature of the battery modules, the measured capacity attenuation rate of the battery modules and the operating conditions of the battery modules.

[0036] The control unit 3 controls the flow and the temperature of the coolant of the main pipe flow valve 208 on the injection main pipe 203 according to the measured average temperature T r of the battery modules, the simulated average temperature T m of the battery modules and the simulated average temperature rise rate V m of the battery modules, and the control unit 3 can also control the flow of the branch pipe flow valve 205 on the corresponding injection branch pipe 201 according to the temperature of the temperature sensor 207 on the return branch pipe 202.

[0037] Figure 2Fig. 1 is a logic diagram of a control method for a thermal management system of a battery cabinet according to the present application. First, the battery module ambient temperature, the battery module capacity attenuation rate and the battery module operating condition of each battery module are monitored, and the measured battery module ambient temperature, the measured battery module capacity attenuation rate and the battery module operating condition are input into the simulation unit to obtain the simulated battery module average temperature T m trend curve and the simulated battery module average temperature rise rate V m trend curve, thereby establishing a simulation database of the battery module average temperature T m and the battery module average temperature rise rate V m under different conditions.

[0038] During system operation, the flow of the manifold flow valve on the injection manifold and the temperature of the coolant in the injection manifold are controlled as a whole, thereby controlling the temperature of the plurality of battery modules in the battery cabinet as a whole. The battery module temperature of each battery module is monitored, and the control unit averages the plurality of battery module temperatures to obtain the measured battery module average temperature T r . The simulated current battery module average temperature T m obtained from the simulation database is compared with the measured battery module average temperature T r . If δT≤3℃, the flow of the manifold flow valve on the injection manifold and the temperature of the coolant in the injection manifold are adjusted according to the measured battery module average temperature T r , the simulated battery module average temperature T m trend curve and the simulated battery module average temperature rise rate V m trend curve, so that the battery module average temperature T r is between 25-40℃; if δT>3℃, the flow of the manifold flow valve on the injection manifold and the temperature of the coolant in the injection manifold are adjusted according to the measured battery module average temperature T r , the simulated battery module average temperature T m trend curve and the simulated battery module average temperature rise rate V m trend curve, so that the battery module average temperature T r is between 25-40℃, and a system warning signal is issued to check for error factors in the system.

[0039] On the basis of overall control of the temperature of the plurality of battery modules in the battery cabinet, the temperature of each battery module is further controlled individually to achieve precise control. The return water temperature T hn of each return water branch pipe is monitored, and the control unit averages the plurality of return water temperatures to obtain the average return water temperature T ha . The return water temperature T hn of each return water branch pipe is compared with the average return water temperature T ha . If Thn > T ha then the flow of the branch flow valve on the corresponding injection branch is increased. If T hn < T ha then the flow of the branch flow valve on the corresponding injection branch is decreased; or the coolant of the injection branch is heated by the heating module on the corresponding injection branch.

[0040] The embodiments of the present application are not intended to limit the present application. Any person skilled in the art, without departing from the technical scheme of the present application, can make many possible changes and modifications to the technical scheme of the present application, or modify equivalent embodiments with the disclosed methods and technical contents. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the content of the technical scheme of the present application, still belongs to the protection scope of the technical scheme of the present application.

Claims

1. A thermal management system for a battery cabinet, the system comprising: The battery cabinet is provided with a plurality of battery modules, a temperature sensor for measuring the ambient temperature of the battery modules, and a battery management system. The thermal management system includes a cooling system, a control unit, and an analog unit. The cooling system includes a plurality of injection branches, a plurality of return water branches, and an injection main pipe. The plurality of injection branches are respectively connected to the plurality of battery modules to respectively inject coolant into the plurality of battery modules. The plurality of return water branches are respectively connected to the plurality of battery modules to respectively discharge the heat-exchanged coolant from the plurality of battery modules. A branch flow valve for controlling the flow of coolant is arranged on the injection branch. A temperature sensor for detecting the return water temperature is arranged on the return water branch. A main pipe flow valve for controlling the flow of coolant is arranged on the injection main pipe. The analog unit is an analog database. Based on the input of the measured battery module ambient temperature, the measured battery module capacity attenuation rate, and the battery module operating condition of the plurality of battery modules, the analog battery module average temperature T m trend curve and the simulated battery module average temperature rise rate V m trend curve, the control unit controls the flow of the main pipe flow valve on the injection main pipe according to the measured battery module average temperature T r , the simulated battery module average temperature T m trend curve and the simulated battery module average temperature rise rate V m trend curve, and the coolant temperature. The control unit controls the flow of the branch flow valve on the corresponding injection branch according to the temperature of the temperature sensor of the return water branch. The control method of the thermal management system of the battery cabinet includes the following steps: (1) monitoring the battery module ambient temperature, the battery module capacity attenuation rate and the battery module operating condition of each battery module, inputting the measured battery module ambient temperature, the measured battery module capacity attenuation rate and the battery module operating condition into the simulation unit to obtain the simulated battery module average temperature trend curve Tm and the simulated battery module average temperature rise rate trend curve Vm; (2) monitoring the battery module temperature of each battery module, the control unit taking the average of the battery module temperatures to obtain the measured battery module average temperature Tr, comparing the simulated battery module average temperature Tm with the measured battery module average temperature Tr, if δT≤3℃, adjusting the flow of the total pipe flow valve on the injection total pipe and the temperature of the coolant injected into the total pipe according to the measured battery module average temperature Tr, the battery module average temperature trend curve Tm and the simulated battery module average temperature rise rate Vm, so that the battery module average temperature Tr is between 25-40℃; if δT>3℃, adjusting the flow of the total pipe flow valve on the injection total pipe and the temperature of the coolant injected into the total pipe according to the measured battery module average temperature Tr, the simulated battery module average temperature trend curve Tm and the simulated battery module average temperature rise rate Vm and issuing a system warning signal; (3) monitoring the return water temperature Thn of each return water branch pipe, the control unit taking the average of the return water temperatures to obtain the average return water temperature Tha, comparing the return water temperature Thn of each return water branch pipe with the average return water temperature Tha, if Thn>Tha, increasing the flow of the branch pipe flow valve on the corresponding injection branch pipe.

2. The thermal management system of a battery cabinet according to claim 1, wherein, A heating module is arranged on the injection branch pipe, and the control unit can control the heating module to heat the coolant in the injection branch pipe.

3. The thermal management system of a battery cabinet of claim 1, wherein, The coolant is a liquid or a gas.

4. The thermal management system of a battery cabinet of claim 1, wherein, If T hn < T ha then reducing the flow of the branch flow valve on the respective injection branch; or, providing a heating module on the injection branch, if T hn < T ha then heating the coolant of the injection branch by the heating module on the respective injection branch.

Images