A battery low-temperature composite preheating system and a battery preheating method
By utilizing the battery low-temperature composite preheating system, which takes advantage of the increased internal resistance of the battery pack for self-heating and combines it with a heater and water pump design, the problems of poor uniformity and large energy loss in low-temperature heating of lithium-ion batteries are solved, achieving rapid, uniform and low-loss battery heating effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2026-04-02
- Publication Date
- 2026-07-31
AI Technical Summary
Existing low-temperature heating technologies for lithium-ion batteries suffer from poor heating uniformity, large energy loss, and difficulty in balancing safety and heating rate. In particular, at low temperatures, the increased viscosity of the electrolyte leads to a decrease in ionic conductivity and an increase in the diffusion resistance of active materials, which affects battery performance and safety.
A low-temperature composite preheating system for batteries is adopted, which utilizes the characteristic of increased internal resistance of battery packs at low temperatures to generate self-heating. Combined with the design of heaters and water pumps, the heat transfer medium is heated by battery pulse discharge to achieve rapid and uniform temperature rise of the battery pack.
It enables rapid and uniform heating of the battery pack under low energy consumption conditions, reduces energy loss during the heating process, and improves the battery's power and safety in low-temperature environments.
Smart Images
Figure CN122494922A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery thermal management technology, and in particular to a battery low-temperature composite preheating system and battery preheating method. Background Technology
[0002] With the rapid development of new energy vehicles and energy storage technologies, lithium-ion batteries have been widely used due to their high energy density and long cycle life. However, lithium-ion batteries exhibit extremely high sensitivity to ambient temperature, especially at low temperatures. Increased electrolyte viscosity leads to decreased ionic conductivity, and the diffusion resistance and charge transfer resistance within the active material surge, directly resulting in reduced usable battery capacity and deteriorated power characteristics. More seriously, low-temperature charging easily triggers lithium plating, and the generated lithium dendrites not only cause irreversible capacity decay but may also puncture the separator, leading to safety accidents. Therefore, to ensure the power performance, safety, and lifespan of batteries in all weather conditions, developing battery thermal management technologies for low-temperature environments has become an urgent need in the industry.
[0003] Existing low-temperature heating solutions can be broadly categorized into external heating and internal heating, based on the location of the heat source. External heating technology primarily relies on an external heat source to transfer heat to the battery. Common methods include using a PTC heater to heat air or a liquid circulating medium, raising the battery temperature through convection heat transfer; or attaching an electric heating film to the surface of the battery module, transferring heat generated by resistance to the battery cells through heat conduction. Although external heating systems are relatively simple in structure and technologically mature, their heating speed is typically slow due to the long heat conduction path and the influence of contact thermal resistance, and they are prone to creating significant temperature gradients within the battery pack.
[0004] Internal heating technology achieves "self-heating" by generating heat inside the battery, effectively shortening the heat transfer path. Common internal heating methods include constant current or pulsed discharge using direct current, and high-frequency AC excitation to generate heat. While internal heating significantly improves the temperature rise rate, a large amount of heat is dissipated onto external resistors during typical internal heating processes, resulting in low battery energy utilization efficiency.
[0005] In summary, existing heating technologies still face challenges in practical applications, including poor heating uniformity, significant energy loss, and the difficulty in balancing safety and heating rate. Achieving rapid, uniform, and low-loss heating of battery systems while ensuring low energy consumption remains a critical technological bottleneck that urgently needs to be overcome in the field of battery thermal management. Summary of the Invention
[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, this application proposes a low-temperature composite preheating system for batteries, which can accurately determine the battery state and perform targeted preheating, with high heating efficiency and reduced energy consumption during the heating process.
[0007] This application also proposes a battery preheating method based on the above-mentioned battery low-temperature composite preheating system.
[0008] The battery low-temperature composite preheating system according to a first aspect embodiment of this application includes: The immersion tank is used to hold the heat transfer medium. A battery pack, which is placed in the immersion chamber and is immersed in the heat transfer medium; A heating assembly includes a storage tank, a heater, and a water pump. The heater and the water pump are electrically connected to the battery pack. The storage tank is used to store the heat transfer medium. The heater is disposed in the storage tank to heat the heat transfer medium. The immersion tank is in communication with the storage tank. The water pump is disposed between the immersion tank and the storage tank. A monitoring component, connected to the immersion tank and the liquid storage tank, is used to detect the temperature of the heat transfer medium; the monitoring component is electrically connected to the heater and the water pump to achieve control. The battery pack utilizes the characteristic of increased internal resistance at low temperatures to achieve self-heating, while simultaneously pulse-discharging the heater to heat the heat transfer medium. The water pump supplies the heat transfer medium from the storage tank to the immersion tank.
[0009] The battery low-temperature composite preheating system according to the embodiments of this application has at least the following beneficial effects: taking advantage of the increased internal resistance of the battery pack at low temperatures, it performs self-heating during the battery pulse discharge process; at the same time, the heater and water pump serve as external loads for the battery, the heater heats the heat transfer medium in the storage tank, and the water pump transports the heated heat transfer medium to the immersion tank; the two preheating methods work together on the battery pack, enabling the battery pack to reach the operating temperature more quickly at low temperatures.
[0010] According to some embodiments of this application, the immersion tank has an inlet and an outlet, the inlet and the outlet are respectively connected to the liquid storage tank through pipes, the inlet is located at the bottom of the immersion tank, and the outlet is located at the top of the immersion tank and is higher than the battery pack.
[0011] According to some embodiments of this application, a gap is reserved between the battery pack and the inner wall of the immersion tank.
[0012] According to some embodiments of this application, the heater is a PTC heater.
[0013] According to some embodiments of this application, the monitoring component includes multiple thermocouples, which are respectively installed in the battery pack, the immersion chamber, and the liquid storage tank.
[0014] The battery preheating method according to the second aspect of this application, based on the above-described battery low-temperature composite preheating system, includes the following steps: The battery pack was subjected to EIS tests at different temperatures and SOCs, as well as temperature rise tests and charge-discharge cycle tests, to establish an electro-thermal-lifetime degradation model for the battery pack. The battery pack is placed in the immersion chamber and the heat transfer medium is injected. During low-temperature startup, the internal resistance of the battery pack generates heat, causing the battery pack temperature to rise spontaneously. The battery pack discharges to drive the heater to heat the heat transfer medium in the storage tank; The water pump is started, driving the heat transfer medium in the storage tank to be transferred to the immersion tank; When the temperature of the battery pack rises to a predetermined temperature, the monitoring component intervenes and stops the battery pack from supplying power to the heater.
[0015] The battery preheating method according to the embodiments of this application has at least the following beneficial effects: the battery can be rapidly heated by self-heating through battery pulse discharge and external liquid convection heat exchange, and the optimal solution set of pulse discharge current amplitude, pulse discharge duty cycle and liquid flow rate can be determined based on the optimization algorithm. The optimal preheating scheme in the scenario can be obtained according to the priority of different application scenario requirements, thereby reducing the battery SOC consumed in the preheating process and the battery capacity decay while ensuring the battery temperature rise rate.
[0016] According to some embodiments of this application, the battery pack's electro-thermal-lifetime degradation model includes a second-order RC equivalent circuit model to characterize the battery dynamic voltage behavior of the battery pack; the electro-thermal-lifetime degradation model includes a thermal model and a lifetime degradation model, the thermal model includes a battery heat generation model, a heat transfer model, and a battery temperature rise model, used to calculate the heat generated by the battery pack in the current state and the temperature change over time; the lifetime degradation model is used to characterize the influence of charge / discharge rate, temperature, and battery discharge cycles on battery capacity degradation.
[0017] According to some embodiments of this application, the monitoring component controls the discharge of the battery pack and the output power of the water pump in real time. The monitoring component uses the pulse discharge current amplitude, pulse discharge duty cycle, and immersion liquid flow rate as optimization variables, and takes maximizing the battery temperature rise rate, minimizing the SOC percentage consumed during the heating process, and minimizing the battery capacity decay as optimization objectives. The optimal solution set of the pulse discharge current amplitude, the pulse discharge duty cycle, and the immersion liquid flow rate is determined by an optimization algorithm.
[0018] According to some embodiments of this application, the monitoring component controls the battery pack to discharge and the water pump power output based on the optimized pulse discharge rate, pulse discharge duty cycle, and immersion liquid flow rate.
[0019] According to some embodiments of this application, after the temperature of the battery pack rises to a predetermined temperature, the heater stops heating, and the water pump continues to run for a period of time to use the thermal inertia of the heat transfer medium to keep the battery pack warm.
[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0021] The accompanying drawings are used to provide a further understanding of the technical solutions disclosed in this application and form part of the specification. They are used together with the embodiments disclosed in this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions disclosed in this application.
[0022] Figure 1 This is a connection diagram of the battery low-temperature composite preheating system according to the first aspect of this application; Figure 2 This is a flowchart of a battery preheating method according to a second aspect embodiment of this application; Figure 3 To optimize the algorithm, the Pareto front of battery capacity decay and temperature rise rate was calculated. Figure 4 To optimize the algorithm, the Pareto front of battery capacity decay and SOC consumption per unit temperature rise rate was calculated.
[0023] Reference numerals: 100-Immersion tank, 110-Inlet, 120-Outlet, 200-Battery pack, 300-Heating assembly, 310-Storage tank, 320-Heater, 330-Water pump, 340-Switching element, 400-Monitoring assembly. Detailed Implementation
[0024] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0025] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0026] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0027] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.
[0028] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0029] With the rapid development of new energy vehicles and energy storage technologies, lithium-ion batteries have been widely used due to their high energy density and long cycle life. However, lithium-ion batteries exhibit extremely high sensitivity to ambient temperature, especially at low temperatures. Increased electrolyte viscosity leads to decreased ionic conductivity, and the diffusion resistance and charge transfer resistance within the active material surge, directly resulting in reduced usable battery capacity and deteriorated power characteristics. More seriously, low-temperature charging easily triggers lithium plating, and the generated lithium dendrites not only cause irreversible capacity decay but may also puncture the separator, leading to safety accidents. Therefore, to ensure the power performance, safety, and lifespan of batteries in all weather conditions, developing battery thermal management technologies for low-temperature environments has become an urgent need in the industry.
[0030] Existing low-temperature heating solutions can be broadly categorized into external heating and internal heating, based on the location of the heat source. External heating technology primarily relies on an external heat source to transfer heat to the battery. Common methods include using a PTC heater to heat air or a liquid circulating medium, raising the battery temperature through convection heat transfer; or attaching an electric heating film to the surface of the battery module, transferring heat generated by resistance to the battery cells through heat conduction. Although external heating systems are relatively simple in structure and technologically mature, their heating speed is typically slow due to the long heat conduction path and the influence of contact thermal resistance, and they are prone to creating significant temperature gradients within the battery pack.
[0031] Internal heating technology achieves "self-heating" by generating heat inside the battery, effectively shortening the heat transfer path. Common internal heating methods include constant current or pulsed discharge using direct current, and high-frequency AC excitation to generate heat. While internal heating significantly improves the temperature rise rate, a large amount of heat is dissipated onto external resistors during typical internal heating processes, resulting in low battery energy utilization efficiency.
[0032] In summary, existing heating technologies still face challenges in practical applications, including poor heating uniformity, significant energy loss, and the difficulty in balancing safety and heating rate. Achieving rapid, uniform, and low-loss heating of battery systems while ensuring low energy consumption remains a critical technological bottleneck that urgently needs to be overcome in the field of battery thermal management.
[0033] In response, this application proposes a low-temperature composite preheating system for batteries. Utilizing the increased internal resistance of the battery pack at low temperatures, the system can preheat the battery pack by utilizing the heat dissipated by the battery pack itself when starting up. Simultaneously, the battery pack pulses discharge to the heater, which heats the heat transfer medium in the storage tank. The heated heat transfer medium is then pumped into the immersion chamber by a water pump. The two preheating methods work together to enable the battery pack to reach its operating temperature more quickly at low temperatures.
[0034] In addition, this application also proposes a battery preheating method based on the above-mentioned low-temperature composite preheating system. The method achieves rapid battery temperature rise through battery pulse discharge self-heating and external liquid convection heat exchange. The optimal solution set of pulse discharge current amplitude, pulse discharge duty cycle and liquid flow rate is determined based on the optimization algorithm. The optimal preheating scheme is obtained according to the priority of different application scenario requirements. While ensuring the battery temperature rise rate, the battery SOC consumed in the preheating process and the battery capacity decay are reduced.
[0035] Reference Figure 1 The battery low-temperature composite preheating system in the first aspect embodiment of this application includes an immersion chamber 100, a battery pack 200, a heating component 300, and a monitoring component 400. The immersion chamber 100 is used to hold the heat transfer medium and provides sufficient space to accommodate the battery pack 200. The battery pack 200 is immersed in the heat transfer medium in the immersion chamber 100, allowing for sufficient heat exchange between the battery pack 200 and the heat transfer medium. In a low-temperature environment, heat is transferred from the heat transfer medium to the battery pack 200 to preheat it. The heating component 300 heats the heat transfer medium, transferring heat to it, which is then conducted to the battery pack 200. The monitoring component 400 monitors the condition of the battery pack 200 and the heating efficiency of the heating component 300, allowing for adaptive adjustments to the heating strategy of the heating component 300 based on the condition of the battery pack 200.
[0036] Specifically, the heating assembly 300 includes a storage tank 310, a heater 320, and a water pump 330. The heater 320 and water pump 330 are electrically connected to the battery pack 200, and their power is directly supplied by the battery pack 200. The storage tank 310 stores the heat transfer medium, and the heater 320 is disposed within the storage tank 310 to heat the heat transfer medium. The immersion tank 100 is interconnected with the storage tank 310, and the water pump 330 is disposed between the immersion tank 100 and the storage tank 310, enabling the water pump 330 to output the heat transfer medium from the storage tank 310 to the immersion tank 100. After the heat transfer medium completes the heat exchange process with the battery pack 200 in the immersion tank 100, it can return to the storage tank 310, achieving a circulating flow of the heat transfer medium.
[0037] The monitoring component 400 is connected to the immersion tank 100 and the storage tank 310 to detect the temperature of the heat transfer medium therein; and the monitoring component 400 is electrically connected to the heater 320 and the water pump 330 to achieve control. Thus, based on the real-time monitoring of the heat transfer medium temperature by the monitoring component 400, closed-loop control of the heating power of the heater 320 and the output power of the water pump 330 can be performed.
[0038] The working principle of this low-temperature composite preheating system is as follows: When the battery pack 200 is started at low temperature, the battery pack 200 utilizes the increased internal resistance at low temperature to achieve self-heating, thereby raising the temperature of the battery pack 200 itself through internal heating; at the same time, the battery pack 200 pulses discharge to the heater 320 to heat the heat transfer medium, and the water pump 330 supplies the heat transfer medium in the storage tank 310 to the immersion box 100, thereby transferring external heat to the battery pack 200 through external heating, and at the same time, it can also utilize the energy dissipated by the battery pack 200 when it is started, reducing the energy loss in the preheating process.
[0039] Furthermore, the immersion tank 100 is provided with an inlet 110 and an outlet 120. The inlet 110 and outlet 120 are respectively connected to the storage tank 310 through pipes. The heat transfer medium in the storage tank 310 enters the immersion tank 100 through the inlet 110, and the heat transfer medium in the immersion tank 100 that has completed heat exchange with the battery pack 200 flows back to the storage tank 310 through the outlet 120. It is worth noting that the inlet 110 is located at the bottom of the immersion tank 100, so that the heat transfer medium that has just entered the immersion tank 100 starts to contact and exchange heat from the bottom of the battery pack 200; the outlet 120 is located at the top of the immersion tank 100 and is higher than the battery pack 200, ensuring that the heat transfer medium overflows from the outlet 120 only after it has fully exchanged heat with the battery pack 200.
[0040] Furthermore, a gap is reserved between the battery pack 200 and the inner wall of the immersion chamber 100, so that the heat transfer medium can flow through the side of the battery pack 200 and fully contact the battery pack 200 for heat exchange.
[0041] Furthermore, the heating assembly 300 also includes a switching element 340, which is connected to the battery pack 200. The switching element 340 is used to control the electrical connection between the heater 320 and the water pump 330. When external heating is not required, the electrical connection between the heater 320 and the water pump 330 can be cut off by the switching element 340, so that preheating can be carried out solely by the thermal effect of the battery pack 200 itself, flexibly adapting to different application scenarios.
[0042] Furthermore, the switching element 340 is electrically connected to the monitoring component 400, so that the monitoring component 400 can control the switching element 340 according to different application scenarios, thereby switching different preheating modes.
[0043] Furthermore, heater 320 is a PTC heater, which has the advantages of low thermal resistance and high heat exchange efficiency. It is an automatic constant temperature and energy-saving electric heater, especially suitable for battery heating, and meets the requirements of high safety.
[0044] Furthermore, the monitoring component 400 includes multiple thermocouples, which are respectively installed in the battery pack 200, the immersion chamber 100 and the liquid storage tank 310, and can monitor the temperature of the battery pack 200 and the heat transfer medium in real time.
[0045] A battery preheating method according to a second aspect embodiment of this application is based on the above-mentioned battery low-temperature composite preheating system, with reference to... Figure 2 This includes the following steps: S100. Perform EIS tests on battery pack 200 at different temperatures and SOCs, as well as temperature rise tests and charge-discharge cycle tests, and establish an electrical-thermal-lifetime degradation model for the battery pack. S200. Place the battery pack 200 in the immersion chamber 100 and inject the heat transfer medium; S300. During low-temperature startup, the internal resistance of the battery pack 200 generates heat, causing the temperature of the battery pack 200 to rise spontaneously, thus performing internal heating. S400. The battery pack 200 discharges to drive the heater 320 to heat the heat transfer medium in the storage tank 310, thereby making full use of the pulse electrical energy generated by the battery pack 200. S500. The water pump 330 starts, driving the heat transfer medium in the storage tank 310 to be transferred to the immersion tank 100 for external heating; S600. When the temperature of the battery pack 200 rises to the predetermined temperature, the monitoring component 400 intervenes and stops the power supply from the battery pack 200 to the heater 320, and the preheating of the battery pack 200 is completed.
[0046] Specifically, during the preheating process of the battery pack 200, the monitoring component 400 monitors the condition of the battery pack 200 in real time based on the electrical-thermal-lifetime degradation model of the battery pack 200. Since the electrical-thermal-lifetime degradation model for the battery pack 200 is established in advance, the preheating process of the battery pack 200 can be adjusted in a targeted manner, reducing the damage to the battery pack 200 caused by the preheating process and improving the preheating efficiency.
[0047] Furthermore, for the electro-thermal-lifetime degradation model, the battery temperature rise rate, the battery SOC consumed during the preheating process, and the percentage of battery capacity degradation can be determined based on the input pulse discharge current amplitude, pulse discharge duty cycle, and immersion liquid flow rate.
[0048] The monitoring component 400 uses pulse discharge current amplitude, pulse discharge duty cycle, and immersion liquid flow rate as optimization variables, and aims to maximize the battery temperature rise rate and minimize the percentage of SOC consumed during the heating process and battery capacity decay. Through an optimization algorithm, it determines the optimal solution set for the pulse discharge current amplitude, pulse discharge duty cycle, and immersion liquid flow rate, i.e., the Pareto front. Figure 3and Figure 4 .
[0049] In practical use, users can prioritize different evaluation indicators according to different application scenarios and assign different weights to them to obtain the optimal preheating solution for that scenario. For example, when a vehicle needs to start quickly in a low-temperature environment, the battery temperature rise rate is given higher priority, and an ultra-fast preheating solution can be selected; for daily use, to ensure the battery's health and reduce battery damage, a life balancing solution can be selected; and when the battery charge is low and continuous driving range needs to be maintained, an energy-saving preheating solution can be selected. The battery pack 200 is heated based on the determined preheating solution.
[0050] The electro-thermal-lifetime degradation model includes a second-order RC equivalent circuit model, characterizing the dynamic voltage behavior of the battery pack 200, and includes the open-circuit voltage (U) characterizing the ideal voltage source. OCV The internal resistance (R0) reflects the internal resistance characteristics, and the two parallel RC branches reflect the electrochemical polarization and concentration polarization effects, respectively, including the electrochemical polarization internal resistance R1, the electrochemical polarization capacitance C1, the concentration polarization internal resistance R2, and the concentration polarization capacitance C2.
[0051] The electro-thermal-lifetime degradation model includes a thermal model and a lifetime degradation model. The thermal model comprises a battery heat generation model, a heat transfer model, and a battery temperature rise model, used to calculate the heat generated by battery pack 200 in its current state and the temperature change over time. The expression for the battery heat generation model is: ; in For battery heat generation power, This represents the battery current, and the third term on the right side of the equation is the reversible heat generated during battery discharge due to electrochemical reactions. It is the entropy-thermal coefficient, which characterizes the relationship between the battery open-circuit voltage and the battery temperature.
[0052] The heat transfer model is used to characterize the process of heat transfer between the battery and the fluid in the immersion chamber 100, and its expression is: ; in, , These are the inlet and outlet temperatures of the liquid submerged in the tank at 100°C. and are the convective heat transfer coefficients between the fluid and the i-th battery and the immersion chamber 100, respectively. and These are the heat exchange areas of the i-th battery and the immersion chamber 100, respectively. For liquid temperature, Let i be the temperature of the i-th battery. The temperature at which the immersion chamber is submerged is 100°C.
[0053] The battery temperature rise model is used to calculate the rate of temperature rise of the battery under its current condition, and its expression is: ; in, For battery quality, This refers to the specific heat capacity of the battery.
[0054] The lifespan degradation model is used to characterize the effects of charge / discharge rate, temperature, and the number of battery discharge cycles on battery capacity degradation. Its expression is as follows: ; in, For battery temperature, The charge / discharge rate of the battery is denoted by n, which represents the ratio of the cumulative discharge capacity to the battery capacity.
[0055] The monitoring component 400 controls the discharge of the battery pack 200 and the output power of the water pump 330 in real time. The monitoring component 400 uses the pulse discharge current amplitude, pulse discharge duty cycle and immersion liquid flow rate as optimization variables, and takes maximizing the battery temperature rise rate, minimizing the SOC percentage consumed during the heating process and minimizing the battery capacity decay as optimization objectives. The optimal solution set of pulse discharge current amplitude, pulse discharge duty cycle and immersion liquid flow rate is determined by the optimization algorithm.
[0056] Different application scenarios require different priorities for different evaluation indicators. Assigning different weights to the evaluation indicators can yield the optimal preheating solution for that scenario. The monitoring component 400 controls the discharge of the battery pack 200 and the power output of the water pump 330 based on the optimized pulse discharge rate, pulse discharge duty cycle, and immersion liquid flow control.
[0057] Furthermore, after the temperature of the battery pack 200 rises to the predetermined temperature, the heater 320 stops heating, and the water pump 330 continues to run for a period of time to use the thermal inertia of the heat transfer medium to keep the battery pack 200 warm.
[0058] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.
Claims
1. A battery low-temperature composite preheating system, characterized in that, include: The immersion tank is used to hold the heat transfer medium. A battery pack, which is placed in the immersion chamber and is immersed in the heat transfer medium; A heating assembly includes a storage tank, a heater, and a water pump. The heater and the water pump are electrically connected to the battery pack. The storage tank is used to store the heat transfer medium. The heater is disposed in the storage tank to heat the heat transfer medium. The immersion tank is in communication with the storage tank. The water pump is disposed between the immersion tank and the storage tank. A monitoring component, connected to the immersion tank and the liquid storage tank, is used to detect the temperature of the heat transfer medium; the monitoring component is electrically connected to the heater and the water pump to achieve control. The battery pack utilizes the characteristic of increased internal resistance at low temperatures to achieve self-heating, while simultaneously pulse-discharging the heater to heat the heat transfer medium. The water pump supplies the heat transfer medium from the storage tank to the immersion tank.
2. The battery low-temperature composite preheating system according to claim 1, characterized in that: The immersion tank has an inlet and an outlet, which are connected to the liquid storage tank via pipes. The inlet is located at the bottom of the immersion tank, and the outlet is located at the top of the immersion tank and is higher than the battery pack.
3. The battery low-temperature composite preheating system according to claim 1, characterized in that: A gap is reserved between the battery pack and the inner wall of the immersion tank.
4. The battery low-temperature composite preheating system according to claim 1, characterized in that: The heater is a PTC heater.
5. The battery low-temperature composite preheating system according to claim 1, characterized in that: The monitoring component includes multiple thermocouples, which are respectively installed in the battery pack, the immersion tank, and the liquid storage tank.
6. A battery preheating method, based on the battery low-temperature composite preheating system according to any one of claims 1 to 5, characterized in that, include: The battery pack was subjected to EIS tests at different temperatures and SOCs, as well as temperature rise tests and charge-discharge cycle tests, to establish an electro-thermal-lifetime degradation model for the battery pack. The battery pack is placed in the immersion chamber and the heat transfer medium is injected. During low-temperature startup, the internal resistance of the battery pack generates heat, causing the battery pack temperature to rise spontaneously. The battery pack discharges to drive the heater to heat the heat transfer medium in the storage tank; The water pump is started, driving the heat transfer medium in the storage tank to be transferred to the immersion tank; When the temperature of the battery pack rises to a predetermined temperature, the monitoring component intervenes and stops the battery pack from supplying power to the heater.
7. The battery preheating method according to claim 6, characterized in that: The battery pack's electro-thermal-lifetime degradation model includes a second-order RC equivalent circuit model, which characterizes the battery's dynamic voltage behavior. The electro-thermal-lifetime degradation model includes a thermal model and a lifetime degradation model. The thermal model includes a battery heat generation model, a heat transfer model, and a battery temperature rise model, which are used to calculate the heat generated by the battery pack in the current state and the temperature change over time. The lifetime degradation model is used to characterize the impact of charge / discharge rate, temperature, and the number of battery discharge cycles on battery capacity degradation.
8. The battery preheating method according to claim 6, characterized in that: The monitoring component controls the discharge of the battery pack and the output power of the water pump in real time. The monitoring component uses the pulse discharge current amplitude, pulse discharge duty cycle, and immersion liquid flow rate as optimization variables, and takes maximizing the battery temperature rise rate, minimizing the SOC percentage consumed during the heating process, and minimizing the battery capacity decay as optimization objectives. The optimal solution set of the pulse discharge current amplitude, the pulse discharge duty cycle, and the immersion liquid flow rate is determined by the optimization algorithm.
9. The battery preheating method according to claim 8, characterized in that: The monitoring component controls the battery pack's discharge and the water pump's power output based on the optimized pulse discharge rate, pulse discharge duty cycle, and immersion liquid flow rate.
10. The battery preheating method according to claim 6, characterized in that: After the temperature of the battery pack rises to the predetermined temperature, the heater stops heating, and the water pump continues to run for a period of time to use the thermal inertia of the heat transfer medium to keep the battery pack warm.