Battery thermal management control method

Abstract

The invention discloses a battery thermal management control method. Comprising the following steps that thermodynamic calculation is conducted on the energy storage device, a heat dissipation model of a battery heat management system in the energy storage device is obtained, and heat dissipation time curves of a battery at different environment temperatures are derived through the heat dissipation model, and a preset heat dissipation time curve in the heat management system of the energy storage device is obtained; and operating the thermal management system, and performing operation control by stages, namely obtaining pre-start operation time of a battery thermal management execution device according to a heat dissipation time curve, sending a pre-start operation instruction to the battery thermal management execution device according to the pre-start operation time, and performing heat dissipation control according to the current temperature and the target temperature of the battery cell during operation. And the temperature of the battery reaches the optimal charging and discharging temperature before the planned charging and discharging time of the energy storage system. Accurate thermal management is carried out on the whole operation period of the energy storage device, the battery safety and the charging and discharging efficiency are improved, and the operation energy consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery thermal management, and particularly relates to a battery thermal management control method. Background Art

[0002] With the rapid development and popularization of new energy, electrochemical energy storage devices have been more and more widely used, and correspondingly, higher requirements are put forward for the control technology and operation efficiency of the overall operation of energy storage devices.

[0003] The battery system is the energy storage medium and the main component of the electrochemical energy storage device, and the battery cell is the basic component unit of the battery system. In the battery system, the operating temperature is a key factor affecting the performance and service life of the battery cell, and plays a crucial role in the safe and efficient operation of the battery cell.

[0004] In the existing operation control of power energy storage devices, the research mainly focuses on the thermal management during the charge and discharge operation of the battery. Regarding the lag characteristics of the thermal management system control and the temperature control of the entire operation cycle of the energy storage device, the prior art has not carried out research on precise active management.

[0005] For example, a thermal management method, an electronic device and a storage medium for a large-scale energy storage system with the patent publication number CN116345014A aims at the charge and discharge operation process of the battery, with the temperature difference control as the goal, and does not consider the lead control of the system. Another example is a thermal management system and method for an energy storage power station with the patent publication number CN117219909A, which considers the heat dissipation management and energy-saving method of the entire operation process of the energy storage power station, but this method cannot make adaptive control according to the characteristics of each energy storage device. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the present invention provides a battery thermal management control method, which realizes the safe, efficient and energy-saving operation of the energy storage device by actively managing the temperature control of the battery during the entire operation cycle of the energy storage device.

[0007] In order to achieve the above object, the present invention provides a battery thermal management control method, including the following steps:

[0008] Step 1, perform thermodynamic calculations on the energy storage device to obtain a heat dissipation model of the energy storage device, and derive the temperature-time curve of the battery cell through the heat dissipation model;

[0009] Step 2, preset the curve described in Step 1 in the thermal management system of the energy storage device;

[0010] Step 3, when the thermal management system operates, read the battery cell temperature, the energy management strategy or the AGVC (system automatic power generation and voltage regulation control) plan in real time, and obtain the pre-start operation time of the execution device of the battery thermal management system according to the curve;

[0011] Step 4: The thermal management system sends a pre-start operation instruction to the execution device according to the pre-start operation time described in Step 3, and performs different-stage control based on the current temperature and target temperature of the battery cells, so that the temperature of the battery reaches the optimal charge-discharge temperature before the planned charge-discharge time of the energy storage system.

[0012] Further, Step 1 is specifically as follows: Combining the heat generation data of the battery cells of the energy storage device, the heat dissipation power of the equipment, the layout of the heat dissipation air ducts or pipes, and the structural layout factors of the energy storage device, performing thermodynamic calculations and simulations to obtain the heat dissipation model of the battery system, considering the different health states of the battery cells, extracting the model influence factors, and performing parameter identification and data fitting on the heat dissipation model to obtain the heat dissipation time curve of the battery cells at different ambient temperatures.

[0013] Further, the different stages in Step 4 include: The standby stage, which is the time from when the battery cells stop charging and discharging operation to the start of pre-operation. The control target is to ensure that the ambient temperature reaches the temperature conditions required for the safe operation of the battery cells.

[0014] The pre-operation stage, which is the time from pre-operation to when the battery cells start charging and discharging. The execution device starts running in advance according to the pre-operation instruction issued by the thermal management system.

[0015] The operation stage: The time from when the battery cells actually start to when they start charging and discharging operation. The control target is that the temperature of the battery cells reaches the optimal charge-discharge temperature.

[0016] Further, the thermal management system includes: An energy management control unit EMU, which is used to preset the heat dissipation model curve of the storage system, read the cell state information of the battery management unit BMU in real time by bus communication, read the energy management strategy or AGVC plan of the EMU, and calculate the pre-start operation time in combination with the model curve and the cell state, set the target temperature value of the battery cells, and control the operation of the thermal management equipment according to the aforementioned energy management strategy.

[0017] The battery management unit BMU is used to collect the temperature, voltage, and current data of the battery cells in real time, perform analysis and calculations, and send the calculated cell temperature, battery depth of discharge DOD, and usage status data to the EMU by bus communication.

[0018] The thermal management control unit CCU is the control unit of the thermal management execution device. It receives the operation instruction of the EMU, and in accordance with the current temperature and target temperature value of the battery cells sent by the EMU, combines the ambient temperature detected by the thermal management system itself, and controls the operation of the thermal management execution device in real time.

[0019] Further, the ambient temperature includes: the battery temperature, which is the measured value of the temperature sensor within the battery module; the ambient temperature inside the battery compartment, which is the ambient temperature outside the battery pack within the battery compartment; the external ambient temperature, which is not measured separately and is set with reference to the ambient temperature of the region where the energy storage device is used.

[0020] Further, the usage status data includes the state of charge (SOC) and the state of health (SOH). By calculating the heat generation data of the battery cells under different states, the influence factors of the battery under different health states are obtained. The intrinsic heat characteristics and heat generation characteristics of the battery cells are different at different aging stages. As the number of charge and discharge cycles of the battery cells increases, aging phenomena occur inside the battery cells, and the specific heat capacity and thermal conductivity of the battery cells also change accordingly. Analyze the laws of heat generation and temperature rise of the battery cells at different aging stages with respect to the change of ambient temperature, and use the SOH value of the battery cells as the influence factor of battery cell aging to characterize the influence of the aging degree of the battery cells on thermal management.

[0021] Further, the execution device includes a radiator, and the battery thermal management system controls the heat generated by the radiator to be delivered to the battery module through an air duct or a liquid cooling pipeline to achieve thermal management.

[0022] Advantages of the present invention:

[0023] The present invention provides a battery thermal management control method. By combining the body characteristics of the energy storage device and performing calculations, a heat dissipation model of the energy storage device is obtained to achieve precise temperature control of the device. By presetting a fitted heat dissipation curve in the system and combining the operation plan of the system, precise thermal management throughout the entire operation cycle of the energy storage device is realized, thereby improving the safety and charge and discharge efficiency of the battery system and reducing the operation energy consumption of the system. Description of the Drawings

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art and the advantages of the present invention, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other structures can be obtained based on the structures shown in these drawings without creative efforts.

[0025] Figure 1 It is a flowchart of step 1 model construction in the method of the present invention.

[0026] Figure 2 It is a flowchart of the method of the present invention. Detailed Embodiments

[0027] See Figure 1 、 Figure 2 , a battery thermal management control method of this embodiment includes the following steps:

[0028] Step 1: Perform thermodynamic calculations on the energy storage device to obtain the heat dissipation model of the battery thermal management system in the energy storage device. Derive the heat dissipation time curve of the battery at different ambient temperatures through the heat dissipation model.

[0029] Step 2: Preset the heat dissipation time curve described in Step 1 in the thermal management system of the energy storage device.

[0030] Step 3: Start running the thermal management system, read the cell temperature, energy management strategy, or AGVC plan in real time, and obtain the pre-start running time of the battery thermal management execution device according to the heat dissipation time curve.

[0031] Step 4: The thermal management system sends a start running instruction to the battery thermal management execution device according to the pre-start running time described in Step 3, and performs heat dissipation control based on the current cell temperature and the target temperature, so that the temperature of the battery reaches the optimal charge and discharge temperature before the planned charge and discharge time of the energy storage system.

[0032] Further, the control of the thermal management system is divided into three stages: the standby stage, which is the time from when the battery stops charging and discharging to the start of pre-operation, and the control target is to ensure that the ambient temperature reaches the temperature conditions required for the safe operation of the cell.

[0033] The pre-operation stage, which is the time from pre-operation to when the battery starts charging and discharging. The execution device starts running in advance according to the pre-operation instruction issued by the thermal management system.

[0034] The operation stage: the time from when the battery actually starts to when it charges and discharges, and the control target is to make the cell temperature reach the optimal charge and discharge temperature.

[0035] Further, the battery thermal management system includes an energy management control unit EMU, a battery management unit BMU, and a thermal management control unit CCU, where: EMU is used to preset the heat dissipation model curve of the storage system, read the cell state information of the battery management unit BMU in real time through bus communication, read the energy management strategy or AGVC plan of the EMU, and calculate the pre-start running time in combination with the model curve and the cell state, set the target temperature value of the cell, and control the operation of the thermal management device according to the foregoing energy management strategy.

[0036] BMU is used to collect the temperature, voltage, and current data of the cell in real time, perform analysis and calculations, and send the calculated cell temperature, battery depth of discharge DOD, and usage status data to the EMU in the form of bus communication.

[0037] The CCU, a control unit for the thermal management execution device, receives the operation instructions from the EMU, and in accordance with the current temperature of the battery cells and the target temperature value sent by the EMU, combines with the ambient temperature detected by the thermal management system itself to control the operation of the thermal management execution device in real time.

[0038] The thermal management system / method can be implemented in the energy management control unit module, or can also be implemented in the thermal management control unit module or the battery management unit module.

[0039] Further, the ambient temperature includes: the battery temperature, which is measured according to the values measured by the temperature sensors within the battery module; the ambient temperature inside the battery compartment, which is the ambient temperature outside the battery pack inside the battery compartment; the external ambient temperature, which is not measured separately and is set with reference to the ambient temperature of the area where the energy storage device is used.

[0040] Further, the usage status data includes the state of charge SOC and the state of health SOH. The heat generation data of the battery under different states is calculated to obtain the influence factors of the battery under different health states. The intrinsic thermal characteristics and heat generation characteristics of the battery are different at different aging stages. As the number of charge and discharge cycles of the battery increases, aging phenomena occur inside the battery, and the specific heat capacity and thermal conductivity of the battery also change accordingly. The laws of heat generation and temperature rise of the battery at different aging stages with the change of ambient temperature are analyzed, and the state of health SOH value of the battery is used as the influence factor of battery aging to characterize the influence of battery aging degree on thermal management.

[0041] Further, the execution device includes a radiator, and the battery thermal management system controls the heat generated by the heat dissipation device to be delivered to the battery module through an air duct or a liquid cooling pipe to achieve thermal management.

[0042] The specific process of establishing the heat dissipation curve of the energy storage device battery system in the embodiment of the present invention is as follows:

[0043] According to the actual temperature of the environment, the operation mode of the energy storage device can be divided into a refrigeration mode and a heating mode. The energy storage device is counted as generating heat in both modes, and the battery and the energy storage cabin are counted as absorbing heat. Correspondingly, the heat generated by the heat dissipation device is delivered to the battery module through an air duct or a liquid cooling pipe.

[0044] Refrigeration mode: Use the first temperature threshold T1. When the ambient temperature T inside the battery compartment is less than T1, start running in the refrigeration mode. Heating mode: Use the second temperature threshold T2. When the ambient temperature T inside the battery compartment is greater than T2, start running in the heating mode. The heat dissipation device includes a refrigeration device and a heating device, and the two can be the same integrated device or can be composed of two different sub-devices.

[0045] 1) Calculation of the cooling capacity of the heat dissipation device

[0046] The heat generated by the heat dissipation device is delivered to the battery module through the air duct or liquid cooling pipeline. Considering the heat transfer loss and safety margin of the air duct / pipeline comprehensively, the safety margin coefficient is taken as k a .

[0047] According to the system configuration, the refrigeration power under the optimal operating state (energy-saving operation or rated operation) of the heat dissipation device is P add , then the output power of the heat dissipation system is

[0048] P add ’ = k a ×P add

[0049] In the formula, P add ’ is the total heat generated in the cabin per second (kW); k a is the safety factor, which is determined by comprehensively considering the cold transfer loss and safety margin.

[0050] 2) Calculation of the heating amount of the heat dissipation system

[0051] In the heating mode, the heating power of the heating device of the heat dissipation system is P hot , k h is the heating safety factor, and the heating power in the cabin is:[[]]

[0052] P hot ’ = k h ×P hot (kW)

[0053] 2.1 Heat absorption of the battery and structural components

[0054] The heat generated by the heat dissipation device is mainly absorbed by the battery module of the energy storage device itself and its structural components. Among them, the mass ratio of the battery module (mainly composed of battery cells and the structural components of the battery module) is the largest, and the mass ratio of the structural components other than the battery module is relatively small, and its temperature rise is also small, which is temporarily ignored as a design margin in the heat generation calculation.

[0055] The specific heat capacity of the battery cell material is C, the weight of a single battery cell is m, and the number of battery cells in the battery system is n. The heat Q rec absorbed by n battery cells is:[[]]

[0056] Q rec = nC(h)mΔT i (kJ)

[0057] The temperature difference ΔT i is:[[]]

[0058] ΔT i = ∑(T i-1 – T i ) = T 0 – Ti (℃)

[0059] T i is the current cell temperature, T 0 is the initial temperature of the cell, T i-1 is the battery cell temperature at the previous moment.

[0060] 2.2 Calculation of ambient thermal power

[0061] The heat transferred from the outside of the battery compartment to the battery compartment mainly comes from solar radiation heat. The calculation formula is based on the maximum radiation heat received by the compartment during extremely hot summer weather:

[0062] P e =∑k j ×A j ×ΔT j

[0063] Among them, P e is the total heat transfer power of the energy storage battery compartment and the environment, kW; k j is the thermal conductivity of the jth surface of the battery compartment, A j It is the area of ​​the outer surface of the battery compartment of the energy storage device that is subject to heat conduction. The battery compartment has a total of 6 surfaces that are subject to heat conduction: the top surface, the long side surface, and the end surface are directly exposed to the sun. The highest temperature of the outer surface takes into account the influence of solar radiation heat; the other 3 surfaces are not directly exposed to the sun, and the outer surface temperature refers to the ambient temperature of the area where the energy storage device is used.

[0064] ΔT j =∑(T jw –T jn )(℃)

[0065] T jw is the cabin outer surface temperature, T jn is the inner surface temperature of the cabin, and is the ambient temperature inside the battery cabin.

[0066] 2.3 Calculation of cell aging influencing factors

[0067] The intrinsic thermal characteristics and heat generation characteristics of electrochemical energy storage batteries are different at different aging stages. As the number of charge and discharge cycles of the battery increases, the battery internally shows signs of aging, and the battery's specific heat capacity and thermal conductivity also change accordingly.

[0068] By analyzing the changes in the heat generation and temperature rise of the battery at different aging stages with the ambient temperature, the battery health status (SOH value) can be used as an influencing factor of battery cell aging to characterize the impact of battery aging on thermal management:

[0069]

[0070] K(h) is the thermal conductivity of the battery cell in the direction of heat transfer, T is the ambient temperature, х is the distance in the direction of heat transfer; A is the cross-sectional area, m2; h is the current SOH value.

[0071]

[0072] The specific heat capacity decreases as the cell ages:

[0073]

[0074] In energy storage systems, the battery's SOC (state of charge) and SOH (state of health) are used to characterize the battery's usage status. The battery management unit (BMU) collects battery status data in real time and obtains the battery's SOH value through an intelligent estimation algorithm. Therefore, the current SOH value in the BMU is obtained as a factor affecting the battery's heat absorption and rate.

[0075] 2.4 Thermal balance calculation and verification

[0076] In summary, according to the law of heat balance, in cooling mode:

[0077] k a ×P add ×t=nC(h)mΔT i +∑k j ×A j ×ΔT j ×t

[0078] In heating mode:

[0079] k h ×P hot ×t=n C(h)mΔT i +∑k j ×A j ×ΔT j ×t

[0080] The target temperature of the battery cell is the optimal charging and discharging temperature. The above formula is used to obtain the internal ambient temperature T of the battery compartment under different external ambient temperature conditions (areas where the energy storage device is used). i The time t value to reach the optimal charge and discharge temperature is set up to establish the corresponding ambient temperature-time curve (T i -t model curve), obtained through simulation or experimental verification, the ambient temperature, battery cell temperature and temperature difference of the device meet the design requirements within the specified time.

[0081] The effect of this embodiment is as follows: by establishing a calculation model of the system, the heat dissipation time curve of the battery cell under different ambient temperatures and health conditions is obtained; a heat dissipation model-time curve is prefabricated in the energy storage system, and combined with the energy storage system operation plan, a control method for precise temperature control of the system is implemented, and precise thermal management of the entire operation cycle of the energy storage system is achieved, thereby improving the safety and charging and discharging efficiency of the battery system and reducing the operating energy consumption of the system.

[0082] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A battery thermal management control method, characterized in that: The following steps are involved: Step 1, perform thermodynamic calculations on the energy storage device to obtain a heat dissipation model of the battery thermal management system in the energy storage device, and derive the heat dissipation time curve of the battery at different ambient temperatures through the heat dissipation model; Step 2, preset the heat dissipation time curve described in step 1 in the thermal management system of the energy storage device; Step 3, control the operation of the thermal management system in stages, including a pre-start operation time for a battery thermal management execution device, send a pre-start operation instruction to the battery thermal management execution device according to the pre-start operation time, and perform heat dissipation control according to the current temperature and target temperature of the battery cell during operation, so that the battery temperature reaches the optimal charging and discharging temperature before the planned charging and discharging time of the energy storage system.

2. The battery thermal management control method according to claim 1, characterized in that: The control of the thermal management system in step 3 is divided into three stages: the standby stage, which is the time from when the battery stops charging and discharging to pre-start, and the control target is to ensure that the ambient temperature reaches the temperature conditions required for safe operation of the battery cell; the pre-start stage, which is the time from pre-start to when the battery starts charging and discharging, and the execution device starts the operation in advance according to the pre-start operation instruction issued by the thermal management system; the operation stage, which is the time from the actual start of the battery to the charging and discharging operation, and the control target is that the battery cell temperature reaches the optimal charging and discharging temperature.

3. The battery thermal management control method according to claim 2, characterized in that: In the step 3, the pre-startup operation time of the system execution device is obtained according to the real-time reading of the battery core temperature, the energy management strategy or the AGVC plan and the heat dissipation time curve.

4. The battery thermal management control method according to any one of claims 1 to 3, characterized in that: The battery thermal management system includes: an energy management control unit, which is used to preset the heat dissipation model curve of the storage system, read the battery cell status information of the battery management unit in real time by bus communication, read the energy management strategy or AGVC plan, and calculate the pre-start operation time in combination with the model curve and the battery cell status, set the target temperature value of the battery cell, and control the operation of the thermal management device according to the above-mentioned energy management strategy; a battery management unit, which is used to collect the temperature, voltage, and current data of the battery cell in real time, and perform analysis and calculation, and send the calculated battery cell temperature, battery discharge depth, and usage status data to the energy management control unit by bus communication; a thermal management control unit, which is used as a control unit of the thermal management execution device, receives the operation instructions of the energy management control unit, and controls the operation of the thermal management execution device in real time according to the current temperature and target temperature value of the battery cell sent by the energy management control unit and the ambient temperature detected by the thermal management system itself.

5. The battery thermal management control method according to claim 4, characterized in that: The ambient temperature includes: battery temperature, which is measured by the temperature sensor in the battery module; the ambient temperature in the battery compartment, which is the ambient temperature outside the battery pack in the battery compartment; and the external ambient temperature, which is not measured separately but is set with reference to the ambient temperature of the area where the energy storage device is used.

6. The battery thermal management control method according to claim 5, characterized in that: The usage status data includes the battery health status. The heat generation data of the battery in different states are calculated to obtain the impact factors of the battery in different health states to characterize the impact of the battery aging degree on thermal management.

7. The battery thermal management control method according to claim 6, characterized in that: The influencing factor adopts the state of health SOH value of the battery, which is estimated according to the state data of the battery.

8. The battery thermal management control method according to claim 7, characterized in that: The execution device includes a radiator, and the battery thermal management system controls the heat generated by the heat dissipation device to be delivered to the battery module through an air duct or a liquid cooling pipe to achieve thermal management.

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