Thermal management system of battery cabinet and control method of thermal management system

Abstract

The invention provides a thermal management system of a battery cabinet and a control method of the thermal management system. The thermal management system of the battery cabinet comprises a cooling system, a control unit and a simulation unit, and the cooling system comprises a cooling main pipe for injecting a coolant, a plurality of injection branch pipes corresponding to each battery module and a plurality of water return branch pipes; the simulation unit provides a simulated battery module average temperature trend curve and a battery module average temperature rise rate trend curve based on the actually measured battery module environment temperature, the battery module capacity fading rate and the battery module operation condition. The control unit is used for controlling the flow and the coolant temperature of a header pipe flow valve on the injection header pipe based on the actually measured battery module average temperature, the simulated battery module average temperature trend curve and the battery module average temperature rise rate trend curve of the plurality of batteries; the control unit controls the flow of the branch pipe flow valves on the corresponding injection branch pipes based on the temperature detected by the temperature sensors on the water return branch pipes.

Description

Technical Field

[0001] The present invention relates to the field of lithium batteries, and in particular to a thermal management system of a battery cabinet and a control method thereof. Background Art

[0002] Lithium-ion batteries are new high-energy batteries that use lithium-embedded compounds as positive and negative electrode materials. Compared with lead-acid batteries and nickel-metal hydride batteries, they have a series of advantages such as high specific energy, high voltage, low self-discharge, good cycle performance and long life. They are increasingly attracting people's attention and are widely used in the field of energy storage. Thermal management of energy storage lithium batteries is a necessary condition to ensure the safe operation of the system. The convection heat transfer coefficient of the liquid cooling system is about 10 times that of forced air cooling. It has more efficient heat dissipation, can also reduce equipment noise, and reduce energy consumption. It has become one of the most common thermal management methods for energy storage systems. The control strategy of the existing liquid cooling thermal management system for energy storage is generally to adjust the unit cooler or flow pump by detecting the medium temperature and pressure in the total circuit. The energy storage system is composed of multiple battery modules. Due to the spatial layout of the system, to ensure the uniformity of the temperature distribution of the entire system, modules in different positions require more refined adjustment and control. Summary of the invention

[0003] In view of the above problems, the present invention provides a thermal management system for a battery cabinet and a control method thereof. The thermal management system of the battery cabinet includes a cooling system, a control unit and a simulation unit. The cooling system includes a cooling main pipe for injecting coolant, multiple injection branches corresponding to each battery module and multiple return branches. 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, battery module capacity attenuation rate and battery module operating conditions. The control unit controls the flow rate and coolant temperature of the main pipe flow valve on the injection main pipe based on the measured battery module average temperature of multiple 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 rate of the branch pipe flow valve on each corresponding injection branch pipe based on the temperature detected by the temperature sensor on each return branch pipe. Through the thermal management system of the battery cabinet and the control method thereof, the temperature of the entire battery system can be accurately and quickly adjusted, and the modules in different positions can be more finely controlled to ensure the uniformity of the temperature distribution of the entire system.

[0004] The technical solution provided by the present invention is as follows:

[0005] The present invention provides a thermal management system for a battery cabinet, wherein 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, and the thermal management system includes a cooling system, a control unit, and a simulation unit. The cooling system includes a plurality of injection branches, a plurality of return branches, and an injection main pipe. The plurality of injection branches are respectively connected to a plurality of battery modules for respectively injecting coolant into the plurality of battery modules, and the plurality of return branches are respectively connected to a plurality of battery modules for respectively discharging the coolant after heat exchange from the plurality of battery modules. A branch flow valve for controlling the flow of the coolant is provided on the injection branch, a temperature sensor for detecting the return water temperature is provided on the return branch, and a main pipe flow valve for controlling the flow of the coolant is provided on the injection main pipe. The simulation unit is a simulation database, and a simulated average temperature T of the battery module is obtained based on the measured ambient temperature of the battery module, the measured capacity attenuation rate of the battery module, and the operating conditions of the battery module of the input plurality of 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 of the battery module T r , simulated average temperature of battery module T m Trend curve and simulated average temperature rise rate V of battery module m The curve controls the flow of the main pipe flow valve on the injection main pipe and the coolant temperature, and the control unit controls the flow of the branch pipe flow valve on the corresponding injection branch pipe according to the temperature of the temperature sensor of the return branch pipe.

[0006] In other words, finite element simulation software such as Comsol and Matlab are used as simulation units of the thermal management system. In the simulation system, the battery charge and discharge curves are used to fit and optimize the lumped parameters of the lumped parameter model, and the attenuation factor is introduced to describe the relationship between the battery capacity attenuation and the change of the ohmic internal resistance with the number of cycles. A simulation database is established to generate the corresponding battery module average temperature T based on different battery module ambient temperatures, battery module capacity attenuation rates, and battery module operating conditions. m Trend data and average temperature rise rate of battery modules V m Trend data, obtain various battery module ambient temperatures, battery module capacity attenuation rates, battery module operating conditions and corresponding battery module average temperatures T m Trend data and average temperature rise rate of battery modules V m During use, based on the simulation database, the corresponding simulated battery module average temperature T can be obtained according to the measured battery module ambient temperature, measured battery module capacity attenuation rate and battery module operating conditions of multiple battery modules. m Trend data and simulated average temperature rise rate V of battery modules mTrend data. Based on the actual measurement at the current moment, the simulation unit can predict the average temperature and heating rate at the next moment, and then adjust the thermal management system in advance. In this way, there is no need to wait until the unevenness between the battery modules is measured before adjusting the temperature. Instead, the average temperature and heating rate at the next moment can be predicted based on the simulation results, and the temperature can be controlled in advance, so as to adjust the thermal management system in a targeted manner. Among them, the ambient temperature of the battery module can be measured by a temperature sensor set near the battery module or on the outer surface of the battery module, the capacity attenuation rate of the battery module can be obtained by measuring the SOH through the battery management system, and the operating conditions of the battery module can include charge and discharge rates, charge and discharge modes, etc.

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

[0008] A heating module can also be provided on the injection branch pipe, and the control unit can control the heating module to heat the coolant in the injection branch pipe. When the return water temperature of a battery module is lower than the average return water temperature, the heating module on the injection branch pipe 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, thereby achieving temperature balance of each battery module. In addition, in colder regions, it is more difficult to start the cooling system due to the low temperature of the coolant input pipeline and the coolant. By providing a heating module on the injection branch pipe, the cooling system of the battery system can be started quickly to ensure the normal operation of the battery system. The coolant in the pipe of the cooling system can be liquid or gas. In other words, unlike traditional air cooling, gas can also be input into the pipe as a coolant.

[0009] The present invention also provides a control method for the thermal management system of the battery cabinet as described above, the control method comprising the following steps:

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

[0011] (2) Monitor the battery module temperature of each battery module, and the control unit takes the average value of multiple battery module temperatures to obtain the measured average battery module temperature T r , the simulated current average battery module temperature T m Compared with the measured average temperature of the battery module T r For comparison, if δT≤3℃, then according to the measured average temperature of the battery module T r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold so that the average temperature of the battery module T r Between 25 and 40°C; if δT>3°C, the measured average temperature of the battery module T r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold and issues a system warning signal;

[0012] (3) Monitor the return water temperature T of each return water branch pipe hn The control unit takes the average of 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 and the average return water temperature T ha For comparison, if T hn > T ha , then increase the flow rate of the branch flow valve on the corresponding injection branch. hn < T ha , then reduce the flow rate of the branch flow valve on the corresponding injection branch; or, set a heating module on the injection branch. If T hn < T ha , the coolant injected into the 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 battery module temperature T in the trend curve m Compared with the measured average temperature of the battery module T r If the difference between them is ≤3°C, it means that the simulated numerical results are accurate and can be obtained by simulating the average temperature T of the battery module. m Trend curve and simulated average temperature rise rate V of battery module mTrend curve to adjust the cooling system. If the average temperature of the simulated battery module T m The current average battery module temperature T in the trend curve m Compared with the measured average temperature of the battery module T r If the difference between the simulated and measured values ​​is greater than 3°C, it means that the simulation results deviate from the measured results. m Trend curve and simulated average temperature rise rate V of battery module m The trend curve regulates the cooling system but at the same time issues a warning signal so that the individual units of the thermal management system can be checked in time and problems can be eliminated quickly.

[0014] The advantages of the present invention are:

[0015] 1) It can adjust and control the battery modules in different positions more precisely to ensure the uniformity of temperature distribution of the entire battery system;

[0016] 2) The temperature and heating rate at the next moment can be predicted based on the simulation results, and the temperature can be controlled in advance, so that the thermal management system can be adjusted in a targeted manner to prevent adjustment lag and better control the temperature uniformity of the entire energy storage battery system. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0019] List of reference numerals:

[0020] 1——Battery cabinet

[0021] 101——Battery Module

[0022] 201——Injection branch

[0023] 202——Return branch pipe

[0024] 203——Injection main

[0025] 204——Heat exchange device

[0026] 205——Branch flow valve

[0027] 206——Heating module

[0028] 207——Temperature sensor

[0029] 208——Main pipe flow valve

[0030] 3 - Control unit

[0031] 4 - Analog unit DETAILED DESCRIPTION

[0032] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings.

[0033] Figure 1 Schematic diagram of a thermal management system for a battery cabinet according to the present invention. Figure 1 As shown, a plurality of battery modules 101 are placed in the battery cabinet 1. The battery cabinet 1 is also provided with a temperature sensor for measuring the ambient temperature of the battery module and a battery management system for receiving signals and issuing system control. The thermal management system of the battery includes a cooling system, a control unit 3 and a simulation unit 4.

[0034] The cooling system is used for cooling the battery module and can also be used for heating the battery module, and includes a plurality of injection branches 201, a plurality of return branches 202 and an injection main pipe 203. The plurality of injection branches 201 are respectively connected to the plurality of battery modules 101 to inject coolant into the plurality of battery modules respectively, and the plurality of return branches 202 are respectively connected to the plurality of battery modules 101 to discharge the coolant after heat exchange from the plurality of battery modules respectively. The discharged coolant is cooled by the heat exchange device 204 and circulates into the battery module again through the injection branch pipe 201 to cool the battery module. A branch flow valve 205 for controlling the flow of coolant and a heating module 206 for heating the coolant are provided on each injection branch pipe 201, 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 coolant is provided on the injection main pipe 203.

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

[0036] The control unit 3 determines the average temperature of the battery module according to the measured average temperature T r , simulated battery module average temperature T m And simulated battery module average temperature rise rate V m The curve controls the flow of the main pipe flow valve 208 on the injection main pipe 203 and the coolant temperature. 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 of the return branch pipe 202.

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

[0038] During system operation, the flow rate of the main pipe flow valve on the injection main pipe and the temperature of the coolant injected into the main pipe should be controlled as a whole, so as to control the temperature of multiple 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 temperatures of multiple battery modules to obtain the measured average battery module temperature T r The simulated current battery module average temperature T obtained from the simulation database m Compared with the measured average temperature of the battery module T r For comparison, if δT≤3℃, then according to the measured average temperature of the battery module T r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold so that the average temperature of the battery module T r Between 25 and 40°C; if δT>3°C, the measured average temperature of the battery module T r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m The trend curve adjusts the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold so that the average temperature of the battery module T r Between 25 and 40°C, a system warning signal is issued to check the error factors in the system.

[0039] On the basis of overall control of the temperature of multiple battery modules in the battery cabinet, the temperature of each battery module is further controlled individually to achieve precise control. Monitor the return water temperature T of each return water branch pipe hn The control unit takes the average of 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 and the average return water temperature T ha For comparison.hn > T ha , then increase the flow rate of the branch flow valve on the corresponding injection branch. hn < T ha , then reduce the flow of the branch flow valve on the corresponding injection branch; or, heat the coolant injected into the branch through the heating module on the corresponding injection branch.

[0040] The specific embodiments of the present invention are not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A thermal management system for a battery cabinet, characterized in that: 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 a simulation unit. The cooling system includes a plurality of injection branches, a plurality of return branches, and an injection main pipe. The plurality of injection branches are respectively connected to the plurality of battery modules for respectively injecting coolant into the plurality of battery modules. The plurality of return branches are respectively connected to the plurality of battery modules for respectively discharging the coolant after heat exchange from the plurality of battery modules. A branch flow valve for controlling the flow of coolant is arranged on the injection branch pipe, a temperature sensor for detecting the return water temperature is arranged on the return branch pipe, and a main pipe flow valve for controlling the flow of coolant is arranged on the injection main pipe. The simulation unit is a simulation database, which provides a simulated battery module average temperature T based on the input measured battery module ambient temperature, measured battery module capacity attenuation rate, and battery module operating condition of the plurality of battery modules. m Trend curve and simulated average temperature rise rate V of battery module m The control unit is based on the measured average temperature T of the battery module. r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m The trend curve controls the flow of the main pipe flow valve on the injection main pipe and the coolant temperature, and the control unit controls the flow of the branch pipe flow valve on the corresponding injection branch pipe according to the temperature of the temperature sensor of the return branch pipe.

2. The thermal management system of the battery cabinet according to claim 1, characterized in that: 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 the battery cabinet according to claim 1, characterized in that: The coolant is liquid or gas.

4. A control method for a thermal management system of a battery cabinet according to any one of claims 1 to 3, characterized in that: The control method comprises the following steps: (1) Monitor the battery module ambient temperature, battery module capacity attenuation rate and battery module operating conditions of each battery module, and input the measured battery module ambient temperature, measured battery module capacity attenuation rate and battery module operating conditions into the simulation unit to obtain the simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m Trend curve; (2) Monitoring the battery module temperature of each of the battery modules, and the control unit averages the temperatures of the plurality of battery modules to obtain an actually measured average battery module temperature T r , the average temperature of the simulated battery module T m Compared with the measured average temperature of the battery module T r For comparison, if δT≤3°C, then according to the measured average temperature of the battery module T r , battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m Adjust the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold so that the average temperature of the battery module T r Between 25 and 40°C; if δT>3°C, then the measured average temperature of the battery module T r , simulated battery module average temperature T m Trend curve and simulated average temperature rise rate V of battery module m Adjust the flow rate of the manifold flow valve on the injection manifold and the temperature of the coolant injected into the manifold and issue a system warning signal; (3) Monitoring the return water temperature T of each return water branch pipe hn The control unit averages the multiple return water temperatures to obtain an average return water temperature T ha , the return water temperature T of each return water branch pipe hn With the average return water temperature T ha For comparison, if T hn > T ha , then increase the flow of the branch flow valve on the corresponding injection branch.

5. The control method of the thermal management system of the battery cabinet according to claim 4, wherein: If T hn < T ha , then reduce the flow of the branch flow valve on the corresponding injection branch; or, set a heating module on the injection branch, if T hn <T ha , the coolant in the injection branch is heated by the heating module on the corresponding injection branch.

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