Composite pin-fin structure power battery module collaborative thermal management device and control method

Abstract

A power battery module collaborative thermal management device and control method having a composite pin-fin structure, the device comprising a circular fin air cooling plate (1), a honeycomb buffer layer (2), a housing (3), a lower cover plate (4), and a coolant pipe (5). The device comprises a stacked cooling layer and a battery layer, and adopts a multi-layer composite collaborative thermal management method comprising a natural cooling layer, a battery layer, a liquid cooling layer, and a phase change cooling layer. The natural cooling layer and the phase change cooling layer passively dissipate heat in the early stage of battery heating. The liquid cooling layer contacts the two battery layers through the maximum surface area, and the inlet conditions are controlled by a temperature control module to achieve heat dissipation and preheating of the battery. The temperature control module monitors the battery temperature Tbat through a temperature sensor and adjusts the coolant temperature Tin and flow rate Vin in real time according to Tbat. The temperature sensor and smoke sensor in the device give an early alarm when thermal runaway is likely to occur. The device solves the problems of dynamic thermal management, thermal runaway warning, and collision buffering of battery modules.

Description

Technical Field

[0001] The present invention relates to a power battery module collaborative thermal management device and a control method of a composite pin-fin structure, belonging to the technical field of power battery thermal management. Background Art

[0002] With the goals of achieving carbon peak and carbon neutrality, lithium-ion batteries have become the mainstream power source for new energy vehicles due to their lack of memory effect and low self-discharge rate. However, fires in new energy vehicles caused by thermal and mechanical abuse of high-energy-density power batteries have also attracted widespread attention from both the industry and society.

[0003] As one of the core components of the three-electric system of new energy vehicles, the power battery is inseparable from the power and safety performance of the entire vehicle. Its power characteristics are easily affected by temperature. Long-term operation of the power battery in a high temperature environment of 40°C in summer or a low temperature environment of -10°C in winter will have irreversible effects on its health status, which is more obvious during high-rate fast charging.

[0004] Existing power battery thermal management technologies mainly include: air cooling and PTC air heating using gas as the medium, composite phase change cooling and heat pipe cooling using phase change materials as the medium, electric heating film heating, and liquid cooling and water PTC heating using liquid as the medium. Among them, gas medium is commonly used in low-end vehicles due to its low thermal conductivity and low cost, and is also seen in coupling with other technologies for collaborative thermal management; phase change materials have excellent temperature balancing performance but are not easy to package and are usually used in conjunction; heat pipes have the highest thermal conductivity coefficient, but are currently less used due to their high cost; electric heating film heating is often used in oil-to-electric platforms, but is rarely used due to its poor temperature uniformity and low temperature rise rate; liquid medium has a high thermal conductivity coefficient, but poor temperature uniformity. Using it in extremely high and low temperature scenarios will increase battery inconsistency. When used in conjunction with phase change materials, the thermal management system can have both high thermal conductivity and high temperature balancing performance.

[0005] During liquid cooling, the active transport of the medium essentially consumes the energy of the power battery. Considering that the actual use scenarios of automobiles are relatively complex, the operating temperature of the power battery and the ambient temperature differ greatly in winter and summer. In order to save the power consumption of the water pump, PTC and Chiller, it is necessary to design a control strategy for the coolant inlet conditions so that the coolant inlet temperature and inlet flow rate need to be adjusted in real time according to the battery temperature to reduce the power consumption of accessories. The step control strategy, linear parameter control strategy and PID control strategy are commonly used in thermal management system control. The step control strategy is a staged constant parameter control process. The control process is too cumbersome and cannot cope with the dynamic temperature changes of the power battery. The PID control strategy has cumbersome early parameter adjustment. The linear parameter control strategy can use temperature as input to make the coolant inlet conditions change linearly with temperature. The control logic is simple and easy to implement.

[0006] Mechanical abuse of power batteries is unavoidable during use. By deploying a suitable buffer layer to mitigate the impact of a collision, mechanical damage to the power battery can be effectively prevented in most scenarios. Power battery collision protection typically involves a multi-layered approach, including overall vehicle structural protection, battery pack housing protection, and battery cell structural accessory protection. Protection of the power battery pack itself is particularly crucial, and wrapping the battery in a structurally stable anti-collision layer effectively protects the battery. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems of traditional power batteries in air cooling and composite phase change thermal management using phase change materials as the medium, and to propose a power battery module collaborative thermal management device and control method with a composite pin-fin structure.

[0008] The technical solution implemented by the present invention is as follows: a composite pin-fin structure power battery module collaborative thermal management device, including an outer shell and a lower cover plate, and also including a circular fin air-cooled plate, a first lithium-ion battery layer, a second lithium-ion battery layer, a liquid-cooled upper cover plate, a liquid-cooled shell, a thermally conductive silicone pad, an external fin-type phase change upper cover plate, a composite phase change material, an embedded fin-type phase change lower cover plate and an oblique-fin liquid cooling plate; the above-mentioned plates and layers are horizontally installed one by one in a container formed by the outer shell and the lower cover plate.

[0009] The first and second lithium-ion battery layers each include 16 identical square lithium-ion battery cells connected in series; the first and second lithium-ion battery layers are connected in parallel to form a battery module; the lithium-ion battery cells are separated by partitions, which are epoxy boards, and 14 temperature sensors are arranged on the sides of the lithium-ion battery cells; the 16 lithium-ion batteries in each layer are divided into two side-by-side groups, and a smoke sensor and a T-shaped nylon water-cooling channel are arranged between the two groups of lithium-ion battery cells; the lithium-ion batteries are connected by copper bars, which are installed on the upper and lower sides of each battery cell tab and attached to the T-shaped nylon water-cooling channel. A U-shaped coolant channel is left inside the T-shaped nylon water-cooling channel, 8 smoke sensors are installed on the upper part of the T-shaped nylon water-cooling channel, and a temperature control module for executing the cooling control strategy is installed at the tail of the T-shaped nylon water-cooling channel.

[0010] Above the first layer of lithium-ion batteries is a round-fin air-cooling plate; below the first layer of lithium-ion batteries is a thermally conductive silicone pad, and below the thermally conductive silicone pad is a liquid-cooled upper cover plate; below the liquid-cooled upper cover plate is an oblique-fin liquid-cooling plate, and the oblique-fin liquid-cooling plate is a liquid-cooled shell; below the liquid-cooled shell is a second layer of lithium-ion batteries, and below the second layer of lithium-ion batteries is an external fin-type phase change upper cover plate and an embedded fin-type phase change lower cover plate, with a composite phase change material between the external fin-type phase change upper cover plate and the embedded fin-type phase change lower cover plate; the embedded fin-type phase change lower cover plate is placed on the lower cover plate.

[0011] The liquid-cooled upper cover plate, the oblique-fin liquid-cooling plate and the liquid-cooling shell constitute the liquid cooling layer of the device; the outer-fin phase-change upper cover plate, the composite phase-change material and the inner-fin phase-change lower cover plate constitute the phase-change cooling layer of the device; the circular-fin air-cooling plate is the natural cooling layer of the device; the first lithium-ion layer is located between the air-cooling layer and the liquid cooling layer; the second lithium-ion layer is located between the liquid cooling layer and the phase-change cooling layer to achieve heat transfer.

[0012] The peripheries of the first lithium-ion battery layer and the second lithium-ion battery layer are both wrapped with a honeycomb buffer layer, the honeycomb buffer layer is made of rubber, and a thermal conductive silicone pad is sandwiched between the battery layer and the liquid cooling layer.

[0013] The circular fin air-cooling plate is a cast circular pin-fin structure with a staggered distribution.

[0014] The liquid cooling shell is provided with a liquid cooling plate cooling liquid inlet and outlet at the front and rear.

[0015] The front and rear of the shell are provided with a device coolant inlet and outlet; the device coolant inlet is connected via a coolant pipeline.

[0016] The liquid cooling layer is connected by a liquid cooling shell, an oblique-fin liquid cooling plate and a liquid cooling upper cover plate through M6 bolts.

[0017] The present invention provides a collaborative thermal management method for a power battery module with a composite pin-fin structure, comprising the following steps:

[0018] (1) At a certain ambient temperature, the power battery module in the device begins to charge or discharge, and the natural cooling layer and the phase change cooling layer passively manage heat through heat convection and heat conduction;

[0019] (2) The temperature sensor detects the battery temperature and records it as Tbat. The temperature control module determines whether the battery temperature is higher than the safety upper limit of 60°C. If so, it transmits a temperature alarm signal. Otherwise, it performs weighted average processing on the temperature data. At the same time, the smoke sensor monitors whether the battery layer generates smoke. If so, it transmits an alarm signal. Otherwise, the monitoring process is cyclical.

[0020] (3) Determine again whether Tbat is in the preset temperature range of 25℃<Tbat<30℃. If so, Tin=Tbat, and the coolant is not cooled or heated, and the coolant pipeline is closed. Otherwise, the coolant is heated or cooled, and the water pump is turned on to drive the coolant Vin, where Vin is the flow rate of the coolant.

[0021] (4) Determine Tbat again. If Tbat is lower than the preset 25°C, use PTC to heat the coolant to Tin. If Tbat is higher than the preset 30°C, use Chiller to cool the coolant to Tin, where Tin is the coolant temperature.

[0022] The beneficial effects of the present invention are as follows: a collaborative thermal management device and control method for a power battery module with a composite pin-fin structure. The battery module first uses air cooling and phase change materials for passive thermal management. When the battery temperature exceeds a preset temperature, a coolant control strategy adjusts the coolant inlet conditions in real time to stabilize the power battery temperature within an appropriate operating temperature range. This provides a timely warning when thermal runaway is imminent. In the event of a collision, the power battery collapses and absorbs energy to protect the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the main structure of the power battery module collaborative thermal management device of the present invention;

[0024] Figure 2 This is a schematic diagram of the explosion structure of the power battery module collaborative thermal management device of the present invention;

[0025] Figure 3 This is a schematic diagram of the explosion structure of the battery layer in the power battery module collaborative thermal management device of the present invention;

[0026] Figure 4 This is a schematic diagram of the liquid cooling layer structure of the power battery module collaborative thermal management device of the present invention;

[0027] Figure 5 This is a schematic diagram of the phase change cooling layer structure of the power battery module collaborative thermal management device of the present invention;

[0028] Figure 6 Schematic diagram of the cross-sectional structure of the power battery module collaborative thermal management device of the present invention;

[0029] Figure 7 This is a flowchart of the operation of the power battery module collaborative thermal management device and control strategy of the present invention;

[0030] In the figure: 1 is a circular fin air-cooled plate; 2 is a honeycomb buffer layer; 3 is an outer shell; 4 is a lower cover; 5 is a coolant pipe; 6 is a partition; 7 is a temperature sensor; 8 is a copper bar; 9 is a smoke sensor; 10 is a T-shaped nylon water-cooling channel; 11 is a temperature control module; 12 is a liquid-cooled upper cover; 13 is an M6 bolt; 14 is a liquid-cooled shell; 15 is a thermally conductive silicone pad; 16 is an external fin-type phase change upper cover; 17 is a composite phase change material; 18 is an internal fin-type phase change lower cover; 19 is an oblique-fin liquid-cooled plate; 20 is a first lithium-ion battery layer; 21 is a second lithium-ion battery layer. DETAILED DESCRIPTION

[0031] The specific embodiment of the present invention is shown in the figure.

[0032] This embodiment uses 32 square batteries to form a power battery module with nominal parameters of 59.2V 20Ah. The battery cells are connected by copper bars and the tabs are cooled by T-shaped water cooling channels.

[0033] like Figure 6 As shown, this embodiment shows a collaborative thermal management device for a power battery module with a composite pin-fin structure, comprising an outer shell 3 and a lower cover plate 4; a circular-fin air-cooling plate 1, a first lithium-ion battery layer 20, a second lithium-ion battery layer 21, a liquid-cooling upper cover plate 12, a thermally conductive silicone pad 15, an outer-finned phase-change upper cover plate 16, a composite phase-change material 17, an inner-finned phase-change lower cover plate 18, and an oblique-fin liquid-cooling plate 19. These plates, layers, and pads are horizontally installed one by one in a rectangular hollow container formed by the outer shell 3 and lower cover plate 4.

[0034] like Figure 1 As shown, the outer packaging layer of this embodiment includes a round-fin air-cooling plate 1, a honeycomb buffer layer 2, an outer shell 3, a lower cover plate 4 and a coolant pipe 5.

[0035] like Figure 2 As shown, the inner layer comprises a battery layer consisting of a first lithium-ion battery layer 20 and a second lithium-ion battery layer 21, a liquid cooling layer consisting of a liquid-cooled upper cover plate 12, an oblique-fin liquid cooling plate 19, a liquid cooling shell 14 and a coolant, and a phase change cooling layer consisting of an outer fin-type phase change upper cover plate 16, a composite phase change material 17 and an embedded fin-type phase change lower cover plate 18.

[0036] In this embodiment, the device housing 3 and the lower cover plate 4 are made of aluminum in one piece. The aluminum housing has the advantages of light weight and high thermal conductivity, which helps to reduce the weight of the system.

[0037] like Figure 3 As shown, the battery layers in this embodiment: the first lithium-ion battery layer 20 and the second lithium-ion battery layer 21 are both laid flat on the thermally conductive silicone pad 15 with the maximum contact area and separated by a partition 6, and a temperature sensor 7 is attached between every two lithium-ion batteries for monitoring the temperature. The positive and negative pole tabs of the lithium-ion battery are connected by a copper bar 8. Considering the heat generated by the tabs, a T-shaped nylon water cooling channel 10 for cooling the copper bar 8 is arranged under the copper bar 8, and a smoke sensor 9 is arranged outside the channel. A temperature control module 11 is installed at the edge of the battery layer for executing the coolant cooling or heating strategy, and the periphery of the lithium-ion battery layer is wrapped with a honeycomb buffer layer 2.

[0038] The copper bar 8 in this embodiment is made of copper foil, which has the advantages of light weight and high thermal conductivity. The T-shaped nylon water-cooling channel is made of nylon, which is an electrical insulator and widely used in the thermal management industry of new energy vehicles. The smoke sensor 9 and temperature sensor 7 are evenly distributed between the lithium-ion batteries, ensuring detection effectiveness while reducing costs.

[0039] In this embodiment, the cooling medium in the T-shaped nylon water-cooling channel 10 and the oblique-fin liquid cooling plate 19 is a water-ethylene glycol mixed solution, with each volume fraction accounting for 50%. The water-ethylene glycol solution has a lower freezing point and smaller dynamic viscosity than pure water.

[0040] The partition 6 in this embodiment is made of epoxy board, which has the functions of sealing and keeping cold, can isolate the heat between the lithium-ion batteries 20, and can effectively prevent the spread of heat diffusion and thermal runaway.

[0041] The honeycomb buffer layer 2 in this embodiment is made of rubber. The rubber is soft and can reduce impact with the honeycomb structure. At the same time, its thermal conductivity is low and it has a heat insulating effect. The compression and rebound properties of the rubber will also increase as the temperature rises.

[0042] like Figure 4 As shown, the liquid cooling layer in this embodiment is composed of a liquid cooling shell 14, an oblique-fin liquid cooling plate 19 and a liquid cooling upper cover plate 12 connected by M6 bolts 13. The oblique fin layout in the fin plate can guide the fluid and reduce flow resistance.

[0043] like Figure 5 As shown, the phase change cooling layer in this embodiment adopts upper and lower different fin-type cover plates, the upper plate is an outer fin-type phase change upper cover plate 16, the lower plate is an inner fin-type phase change lower cover plate 18, and the composite phase change material 17 is filled between the two cover plates.

[0044] In this embodiment, the outer fins and the inner fins are nested, and the nested fins have a collapse buffering effect.

[0045] In this embodiment, the device utilizes stacked cooling and battery layers, maximizing the cooling surface area of ​​the upper and lower surfaces of the liquid cooling plate, thus maximizing cooling / preheating of the battery modules. The fin structure increases the contact area between the liquid cooling plate and the cooling medium, providing greater heat transfer capacity.

[0046] The summer high-temperature cooling process of this embodiment is as follows: Under high-temperature summer conditions, the heat generated by the first lithium-ion battery layer 20 is transferred to the upper and lower surfaces of the liquid-cooled upper cover plate 12 and the liquid-cooled housing 14 via the thermally conductive silicone pad 15. Simultaneously, the heat from the upper battery layer is transferred to the top circular-fin air-cooling plate 1 for natural convection cooling. The heat from the second lithium-ion battery layer 21 is transferred to the bottom externally finned phase-change upper cover plate 16. When the battery temperature exceeds the melting point of the phase-change material, the phase-change material absorbs the heat generated by the battery through the latent heat of phase change. During lithium-ion battery operation, the temperature sensor 7 monitors the battery temperature in real time. If the temperature exceeds the set upper limit of 30°C, the temperature control module 11 adjusts the water pump or chiller to increase the coolant flow rate or reduce the coolant temperature.

[0047] In this embodiment, the winter low-temperature heating process: In low-temperature winter environments, the bottom phase-change material layer provides a certain degree of insulation. When this device is adapted for pure electric vehicles operating for extended periods in northern winters, the upper circular-fin air-cooling plate 1 can be optionally equipped with a phase-change material layer to provide better temperature control in winter. During operation of the first lithium-ion battery layer 20, the temperature sensor 7 monitors the battery temperature in real time. If the battery temperature falls below the set lower limit of 25°C, the temperature control module 11 adjusts the water pump or PTC to increase the coolant flow rate or raise the coolant temperature.

[0048] In this embodiment, a phase-change material layer is installed at the bottom. The composite phase-change material 17 has high compression resilience, mitigating impact and protecting the second lithium-ion battery layer 21 during a vehicle bottom collision, thereby improving the vehicle's roadworthiness. A honeycomb buffer layer 2 is installed on the side of the lithium-ion battery layer in this device, allowing it to collapse and absorb energy to protect the battery during a side collision.

[0049] The composite phase-change material 17 in this embodiment is a paraffin wax / expanded graphite composite phase-change material, with the expanded graphite having a mass fraction of 20%. The expanded graphite has a porous structure that absorbs liquid paraffin and prevents leakage. When filling the composite phase-change material 17, 20% of the space is reserved for the composite phase-change material 17 to absorb heat and expand.

[0050] In this embodiment, the external fin-type phase change upper cover plate 16, the internal fin-type phase change lower cover plate 18, the oblique-fin type liquid cooling plate 19 and the circular-fin type air cooling plate 1 are all made of aluminum, which is convenient for modular replacement.

[0051] like Figure 7 As shown, this embodiment provides a collaborative thermal management control method for a power battery module with a composite pin-fin structure, comprising the following steps:

[0052] Step 1: At a certain ambient temperature, the power battery module in the device begins to charge or discharge, and the natural cooling layer and the phase change cooling layer perform passive thermal management through heat convection and heat conduction.

[0053] Step 2: The temperature sensor 7 detects the battery temperature and records it as Tbat. The temperature control module 11 determines whether the temperature of the lithium-ion battery layer 20 is higher than the safety upper limit of 60°C. If so, a temperature alarm signal is transmitted. Otherwise, a weighted average is performed on the temperature data. Simultaneously, the smoke sensor 9 monitors whether smoke is generated in the battery layer. If so, an alarm signal is transmitted. Otherwise, the monitoring process is repeated.

[0054] Step 3: Determine again whether Tbat is in the preset temperature range of 25℃<Tbat<30℃. If so, the coolant temperature Tin=Tbat, and the coolant is not cooled or heated, and the coolant pipe 5 is closed. Otherwise, the coolant is heated or cooled, and the water pump is turned on to drive the coolant Vin.

[0055] Step 4: Determine Tbat again. If Tbat is lower than the preset temperature of 25°C, use PTC to heat the coolant to Tin. If Tbat is higher than the preset temperature of 30°C, use Chiller to cool the coolant to Tin.

[0056] Furthermore, the coolant Tin and the coolant flow rate Vin are calculated based on Tbat, and 0.075 and 0.008 in the control strategy are temperature control and speed control coefficients, which can be customized and adjusted.

Claims

1. A power battery module collaborative thermal management device with a composite pin-fin structure, comprising a housing and a lower cover, characterized in that: The device also includes a circular fin air-cooling plate, a first lithium-ion battery layer, a second lithium-ion battery layer, a liquid-cooling upper cover plate, a liquid-cooling shell, a thermally conductive silicone pad, an external fin-type phase change upper cover plate, a composite phase change material, an internal fin-type phase change lower cover plate, and an oblique fin liquid-cooling plate; The first lithium-ion battery layer and the second lithium-ion battery layer each include 16 square lithium-ion battery cells connected in series; the first lithium-ion battery layer and the second lithium-ion battery layer are connected in parallel to form a battery module; the lithium-ion battery cells are separated by partitions, and 14 temperature sensors are arranged on the sides of the lithium-ion battery cells; the 16 lithium-ion batteries in each layer are divided into two groups side by side, and a smoke sensor and a T-shaped nylon water-cooling channel are provided between the two groups of lithium-ion battery cells; the lithium-ion batteries are connected by copper bars, which are installed on both the upper and lower sides of each battery cell tab, and the copper bars are attached to the T-shaped nylon water-cooling channel, and a U-shaped coolant channel is left inside the T-shaped nylon water-cooling channel. Eight smoke sensors are installed on the upper part of the T-shaped nylon water-cooling channel, and a temperature control module for executing the cooling control strategy is installed at the tail of the T-shaped nylon water-cooling channel; The first lithium-ion battery layer is provided with a circular fin air-cooling plate; the first lithium-ion battery layer is provided with a thermally conductive silicone pad, and the thermally conductive silicone pad is provided with a liquid-cooling upper cover plate; the liquid-cooling upper cover plate is provided with an oblique fin liquid-cooling plate and a liquid-cooling housing; the liquid-cooling housing is provided with a second lithium-ion battery layer, and the second lithium-ion battery layer is provided with an external fin-type phase-change upper cover plate and an internal fin-type phase-change lower cover plate, with a composite phase-change material between the external fin-type phase-change upper cover plate and the internal fin-type phase-change lower cover plate; the internal fin-type phase-change lower cover plate is attached to the lower cover plate; The liquid-cooled upper cover plate, the oblique-fin liquid-cooling plate and the liquid-cooling shell constitute the liquid cooling layer of the device; the outer-fin phase-change upper cover plate, the composite phase-change material and the inner-fin phase-change lower cover plate constitute the phase-change cooling layer of the device; the circular-fin air-cooling plate is the natural cooling layer of the device; the first lithium-ion battery layer is located between the air-cooling layer and the liquid cooling layer; the second lithium-ion battery layer is located between the liquid cooling layer and the phase-change cooling layer to achieve heat transfer.

2. The power battery module collaborative thermal management device of a composite pin-fin structure according to claim 1, characterized in that: The peripheries of the first lithium-ion battery layer and the second lithium-ion battery layer are both wrapped with a honeycomb buffer layer, the honeycomb buffer layer is made of rubber, and a thermal conductive silicone pad is sandwiched between the battery layer and the liquid cooling layer.

3. The power battery module collaborative thermal management device of a composite pin-fin structure according to claim 1, characterized in that: The circular fin air-cooling plate is a cast circular pin-fin structure with a staggered distribution.

4. The power battery module collaborative thermal management device of a composite pin-fin structure according to claim 1, characterized in that: The liquid cooling shell is provided with a liquid cooling plate cooling liquid inlet and outlet at the front and rear.

5. The power battery module collaborative thermal management device with a composite pin-fin structure according to claim 1, characterized in that: The front and rear of the shell are provided with a device coolant inlet and outlet; the device coolant inlet is connected via a coolant pipeline.

6. The power battery module collaborative thermal management device with a composite pin-fin structure according to claim 1, characterized in that: The liquid cooling layer is tightly connected by a liquid cooling shell, an oblique-fin liquid cooling plate and a liquid cooling upper cover plate through M6 bolts.

7. A method for collaborative thermal management of a power battery module with a composite pin-fin structure using the power battery module collaborative thermal management device with a composite pin-fin structure according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) At a certain ambient temperature, the power battery module in the device begins to charge or discharge, and the natural cooling layer and the phase change cooling layer passively manage heat through heat convection and heat conduction; (2) The temperature sensor detects the battery temperature and records it as Tbat. The temperature control module determines whether the battery temperature is higher than the safety upper limit of 60°C. If so, it transmits a temperature alarm signal. Otherwise, it performs weighted average processing on the temperature data. At the same time, the smoke sensor monitors whether the battery layer generates smoke. If so, it transmits an alarm signal. Otherwise, the monitoring process is cyclical. (3) Determine again whether Tbat is in the preset temperature range of 25℃<Tbat<30℃. If so, Tin=Tbat, and the coolant is not cooled or heated, and the coolant pipeline is closed. Otherwise, the coolant is heated or cooled, and the water pump is turned on to drive the coolant to run, thereby changing the coolant flow rate Vin; (4) Determine Tbat again. If Tbat is lower than the preset 25°C, use PTC to heat the coolant to Tin. If Tbat is higher than the preset 30°C, use Chiller to cool the coolant to Tin. Tin is the temperature of the coolant after temperature change.

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