Vehicle battery thermal management method and variable thermal resistance heat conduction device

Abstract

The present application relates to the field of battery management system, disclose a kind of vehicle battery thermal management method and variable thermal resistance heat conduction device, the device of the present application includes liquid cooling plate, inclined wedge pressurizing layer and hydraulic pressure equalizing layer, by inclined wedge pressurizing layer jacking or retracting liquid cooling plate, hydraulic pressure equalizing layer injection or liquid discharge makes elastomeric septum expand or shrink, realize the two-way active adjustment of heat conduction thermal resistance.The method of the present application includes: obtaining battery SOC, temperature, current, rate and other parameters, based on SOC macro trend prediction, based on real-time parameter fine trend prediction and combined with thermal management system capability correction, according to the prediction result executes long-term strategy (adjusts temperature control threshold) and short-term strategy (adjusts compressor, water pump, fan and cooperates adjustment heat conduction thermal resistance), the present application realizes prediction active temperature control, reduces battery temperature fluctuation and execution component frequent start-stop, prolongs battery life, improves vehicle energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery management systems, and more specifically to a vehicle battery thermal management method and a variable thermal resistance heat conduction device. Background Technology

[0002] In pure electric vehicles, the power battery generates a certain amount of heat during charging and discharging. When the battery temperature is too high, it can accelerate the aging of the cell materials and lead to performance degradation, while also increasing the risk of thermal runaway. Conversely, when the battery temperature is too low, it can reduce the battery's charging and discharging capacity, decrease power response performance, and adversely affect the vehicle's range and battery lifespan.

[0003] To ensure the stable operation of the power battery within a suitable temperature range, vehicles typically employ a battery thermal management system to regulate the battery temperature. In existing technologies, battery thermal management systems mostly utilize liquid cooling for battery thermal management. This involves circulating coolant exchanging heat with the battery pack to regulate the battery temperature and maintain it within a suitable range (typically 20–40°C).

[0004] The battery thermal management system can provide a safe and stable operating environment for the power battery and has a significant impact on the vehicle's power performance, energy consumption level, and power battery cycle life.

[0005] Existing battery thermal management systems in pure electric vehicles typically rely on thermal management requests from the Battery Management System (BMS) as the primary control basis. For example, when the BMS detects that the battery temperature exceeds a set threshold, it sends a cooling request to the thermal management system; when the battery temperature falls below the set threshold, it sends a heating request. The thermal management system then activates corresponding actuators, such as compressors, circulating water pumps, or heating devices, based on the received requests, thereby regulating the battery temperature. In some optimized systems, a few battery operating parameters (such as the maximum battery temperature) are also incorporated for simple auxiliary control of the thermal management system.

[0006] Based on the above technical solutions, existing battery thermal management systems still have certain shortcomings in practical applications, mainly in the following aspects: (1) Accelerates battery aging and shortens cycle life.

[0007] Because existing thermal management systems primarily rely on temperature threshold triggering control and lack the ability to predict and actively adjust battery temperature trends, battery temperatures are prone to significant fluctuations during actual operation, making it difficult to maintain stability within the optimal operating temperature range over extended periods. Prolonged exposure to large temperature fluctuations accelerates the aging process of internal electrochemical materials, leading to faster capacity decay and ultimately shortening the cycle life of the power battery.

[0008] (2) Reduce the service life of the actuators and increase maintenance costs.

[0009] Under temperature threshold-based control strategies, components in thermal management systems, such as compressors, pumps, and fans, often need to be frequently started and stopped in response to temperature changes. Frequent start-stop operations increase the impact and wear on mechanical components, and long-term operation can lead to a decrease in the reliability of these components, thereby increasing system maintenance and component replacement costs.

[0010] (3) Reduced system energy efficiency, affecting overall vehicle performance.

[0011] Because existing thermal management systems typically exhibit a certain lag in responding to battery heating conditions, activating cooling or heating devices only after the battery temperature has significantly deviated from the target temperature range can lead to the thermal management system operating at higher power, thereby increasing energy consumption. Furthermore, unstable temperature control can also affect the battery's charging and discharging efficiency and the energy utilization efficiency of the vehicle's powertrain, negatively impacting overall vehicle performance and range.

[0012] (4) The thermal resistance adjustment capability is limited, making it difficult to achieve refined thermal management.

[0013] In existing battery thermal management systems, the liquid cooling plate and battery cell typically maintain a fixed contact. The thermal resistance is essentially determined after system design and cannot be dynamically adjusted based on the battery's actual heating state. When the battery is under low-heat conditions, the fixed low thermal resistance leads to unnecessary heat loss, increasing the energy consumption burden of the thermal management system. When the battery is under high-heat conditions, excessively high thermal resistance hinders timely heat conduction, causing the battery temperature to rise too quickly. Some existing technologies attempt to improve the contact effect by adding thermally conductive pads or phase change materials between the liquid cooling plate and the cell; however, these solutions still fall under the category of passive adjustment and cannot achieve active, bidirectional, real-time adjustment of thermal resistance, making it difficult to meet the requirements for fine-grained temperature control under varying operating conditions.

[0014] (5) The coupling of the actuator is low and the collaborative control capability is insufficient.

[0015] In existing technologies, there is a lack of coordination between the active temperature control components of the thermal management system (such as compressors, water pumps, and fans) and the internal heat-conducting structures of the battery pack (such as liquid cooling plates and thermal pads). The thermal management system can only indirectly affect the battery temperature by changing the coolant temperature or flow rate, and cannot actively adjust the heat transfer efficiency between the battery and the cooling medium. This "external regulation, internal passivity" control mode makes the thermal management system slow to respond to sudden changes in battery heat generation, with low adjustment accuracy, making it difficult to achieve "on-demand heat transfer," further exacerbating temperature fluctuations and energy waste.

[0016] (6) Lack of forward-looking judgment on battery temperature change trends.

[0017] Existing thermal management systems only respond after the battery temperature reaches a set threshold. This "retroactive adjustment" control logic fails to fully utilize battery operating status information (such as state of charge, operating current, and operating rate) to predict battery temperature change trends. For example, under high-power discharge conditions, battery temperature often exhibits significant upward inertia. By the time cooling is initiated after reaching the threshold, the battery temperature may have already overshooted to a higher level. Conversely, towards the end of charging, battery heat generation gradually decreases, and maintaining a high cooling power would result in energy waste. Due to the lack of proactive judgment on temperature change trends, the thermal management system remains in a "lagging response" state, making it difficult to achieve proactive and preventative temperature control.

[0018] In summary, existing battery thermal management systems for pure electric vehicles have significant shortcomings in terms of temperature control strategies, thermal resistance adjustment capabilities, multi-actuator coordination, and trend prediction capabilities. There is an urgent need for a new battery thermal management control method that can achieve battery temperature change trend prediction, bidirectional active adjustment of thermal conductivity and thermal resistance, and coordinated control of the thermal management system. Summary of the Invention

[0019] The purpose of this invention is to solve the problems in the background art and provide a vehicle battery thermal management method and a variable thermal resistance heat conduction device.

[0020] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A variable thermal resistance heat conduction device includes a liquid cooling plate, a battery cell, a wedge-shaped pressure boosting layer, and a hydraulic pressure equalization layer. The liquid cooling plate is disposed below the battery cell, the wedge-shaped pressure boosting layer is disposed below the liquid cooling plate, and the hydraulic pressure equalization layer is disposed between the upper surface of the liquid cooling plate and the battery cell.

[0021] This invention achieves active, bidirectional, and real-time adjustment of the thermal resistance between the liquid cooling plate and the battery cell by setting up a wedge-shaped pressure-boosting layer and a hydraulic pressure-equalizing layer. When enhanced heat dissipation is required, the wedge-shaped pressure-boosting layer can push the liquid cooling plate upward to increase the contact pressure. At the same time, the hydraulic pressure-equalizing layer injects heat-conducting liquid into the sealed cavity, causing the elastic diaphragm to expand and fill the microscopic unevenness on the bottom surface of the battery cell. The two work together to significantly reduce the thermal resistance within seconds, quickly responding to sudden changes in battery heat generation and filling the time vacuum period of traditional thermal management systems waiting for coolant circulation adjustment, thus avoiding temperature overshoot. When heat dissipation needs to be reduced, the wedge-shaped pressure-boosting layer retracts to reduce the contact pressure. In conjunction with the pressure relief valve core, the liquid actively drains, causing the elastic diaphragm to contract and reset, effectively increasing the thermal resistance. This prevents excessive heat from being carried away by the coolant when the battery is at low temperature or when a temperature drop is predicted, thus playing a heat preservation role. This device enables the macroscopic cooling capacity and microscopic heat transfer efficiency of the thermal management system to work in synergy, avoiding the energy waste under low-heat conditions and insufficient heat dissipation under high-heat conditions caused by the fixed thermal resistance structure. At the same time, the expansion and bonding of the elastic diaphragm solves the problem of inconsistent contact thermal resistance caused by microscopic unevenness on the bottom surface of the cell, thereby improving the uniform temperature performance of the battery pack and the energy efficiency level of the thermal management system.

[0022] Preferably, the wedge pressurization layer includes a wedge pusher block, a roller, an electric push rod, and a fixing plate. The motor end of the electric push rod is fixed to the fixing plate, and the push rod end of the electric push rod is fixedly connected to the wedge pusher block. The roller is rotatably disposed below the liquid cooling plate, so that when the wedge pusher block moves horizontally, the roller pushes the liquid cooling plate upward.

[0023] This invention achieves active, precise, and rapid adjustment of the contact pressure between the liquid cooling plate and the battery cell by setting up a wedge-shaped pressure-increasing layer composed of a wedge pusher, rollers, an electric push rod, and a fixing plate. When the electric push rod extends, it pushes the wedge pusher to move horizontally. Its inclined surface, in conjunction with the rollers, converts the horizontal thrust into a vertical upward lifting force, causing the liquid cooling plate to be lifted smoothly upward, thereby increasing the contact pressure between the liquid cooling plate and the battery cell, effectively reducing the contact thermal resistance, and enhancing the heat dissipation capacity. When the electric push rod retracts, the wedge pusher moves backward, and the liquid cooling plate naturally descends under the action of gravity, reducing the contact pressure and increasing the contact thermal resistance, thus playing a role in heat preservation.

[0024] This wedge-shaped pressure-boosting layer employs a slope-roller transmission structure, efficiently converting the horizontal motion of the electric actuator into vertical lifting motion. It boasts advantages such as compact structure, high transmission efficiency, and fast response speed. Furthermore, the electric actuator is only briefly energized when changing position, maintaining its current position without energy consumption in steady state, resulting in extremely low power consumption. Compared to traditional spring preload or airbag pressurization methods, this solution enables continuous stepless adjustment of contact pressure with a wide adjustment range and high control precision. It can dynamically match the optimal contact pressure based on the real-time heating state of the battery, avoiding the problems of excessive pressure leading to unnecessary heat loss at low heating levels and insufficient pressure limiting heat dissipation at high heating levels, which are common with fixed pressure structures. This significantly improves the energy efficiency and temperature control flexibility of the thermal management system.

[0025] Preferably, each battery cell has a hydraulic equalization layer underneath it. More importantly, each battery cell has an independent hydraulic equalization layer underneath it. The hydraulic equalization layer includes a sealing frame, an elastic diaphragm, and a hydraulic control system. The elastic diaphragm can be pressed into the sealing frame and the top of the liquid cooling plate to form a sealed cavity. The sealed cavity is filled with a heat-conducting liquid. The hydraulic equalization layer is used to control the injection and discharge of the heat-conducting liquid, so that the elastic diaphragm expands to fill the microscopic unevenness on the bottom surface of the battery cell or contracts to reset. The thermal resistance between a single cell and the liquid cooling plate can be independently adjusted, so that the thermal management system can allocate heat according to the actual heating state of each cell. The hot cells have reduced resistance for enhanced heat dissipation, and the cold cells have increased resistance for heat preservation. This solves the coupling dilemma of all cells being affected by each other in the traditional solution, and significantly improves the temperature uniformity of the battery pack.

[0026] Preferably, the hydraulic control system includes a miniature piston pump, a linkage-type liquid inlet self-locking valve assembly, and a pressure sensor. The linkage-type liquid inlet self-locking valve assembly is equipped with an inlet pipe, a pressure relief pipe, and an access pipe. The miniature piston pump is connected to the inlet pipe of the linkage-type liquid inlet self-locking valve assembly via a pipeline. The access pipe is connected to the liquid inlet of the sealed cavity. The pressure relief pipe is connected to the liquid storage tank via a pipeline. The pressure sensor is installed at the liquid outlet of the sealed cavity to monitor the liquid pressure in real time and feed it back to the controller.

[0027] This invention achieves precise, reliable, and self-locking control of the volume of heat-conducting liquid in a sealed cavity by setting up a hydraulic control system consisting of a micro piston pump, a linked liquid inlet self-locking valve assembly, a pressure sensor, and corresponding pipelines. When enhanced heat dissipation is required, the controller starts the micro piston pump, actively injecting heat-conducting liquid into the sealed cavity through the liquid inlet pipe and the linked liquid inlet self-locking valve assembly, causing the elastic diaphragm to expand and adhere to the bottom surface of the battery cell. The pressure sensor monitors the pressure inside the cavity in real time and provides feedback. When the preset value is reached, the injection stops, ensuring precise and controllable expansion. When reduced heat dissipation is required, the controller opens the pressure relief pipe, and the heat-conducting liquid flows back to the storage tank through the pressure relief pipe. The elastic diaphragm contracts and resets. Similarly, the pressure sensor monitors the pressure until the preset minimum value is reached, at which point the pressure relief is closed. This hydraulic control system works in conjunction with the wedge-shaped pressure boosting layer to achieve bidirectional, precise, and low-energy-consumption adjustment of thermal resistance. This allows the thermal management system to change the interface heat transfer efficiency as needed according to the battery's heating state, significantly improving the precision of thermal management and energy utilization efficiency.

[0028] Preferably, the linkage-type liquid inlet self-locking valve assembly includes a valve seat, a liquid inlet valve core, a pressure relief valve core, a linkage rod, an upper baffle, an upper push rod, a lower baffle, a lower push rod, and an electromagnet. The liquid inlet pipe, the pressure relief pipe, and the inlet pipe are disposed on the valve seat. The liquid inlet pipe has a liquid inlet groove, and the liquid inlet valve core is slidably disposed on the liquid inlet groove. The pressure relief pipe has a pressure relief groove, and the pressure relief valve core is slidably disposed on the pressure relief groove. The linkage rod is disposed on the back of the liquid inlet valve core. The upper push rod and the lower push rod are fixed on both sides of the linkage rod and penetrate the groove wall of the pressure relief groove. The upper baffle and the lower baffle are rotatably disposed at the groove opening of the pressure relief groove with the middle as the center, so that when the upper push rod and the lower push rod are pushed out, they can drive the upper baffle and the lower baffle to rotate and abut against the pressure relief valve core. The electromagnet controls the movement of the pressure relief valve core.

[0029] This invention achieves automatic mechanical locking of the pressure relief valve core during the injection process by setting up a linkage-type self-locking valve assembly consisting of a valve seat, an inlet valve core, a pressure relief valve core, a linkage rod, an upper baffle, a lower baffle, an upper push rod, a lower push rod, and an electromagnet. This significantly improves the reliability and safety of the hydraulic control system, thereby ensuring the stable operation of the entire variable thermal resistance heat conduction device.

[0030] When the micro piston pump starts injecting liquid, the inlet valve core slides open the inlet passage under hydraulic pressure. At the same time, the linkage rod drives the upper and lower push rods to extend, pushing the upper and lower baffles to rotate and block the pressure relief valve core, locking it in the closed position. This automatically prevents the pressure relief valve from being accidentally opened due to vibration, pressure fluctuations, or electromagnetic interference during the injection process, ensuring that the heat transfer liquid only enters and does not exit, and that the pressure in the sealed cavity is stably established. When the injection is completed and the micro piston pump stops working, the inlet valve core automatically resets and closes the inlet passage under the action of the compression spring. The linkage rod retracts, and the upper and lower baffles are unlocked. At this time, the pressure relief valve core returns to its free state and can be opened by electromagnet control for active liquid discharge. This linkage mechanism mechanically eliminates the possibility of the pressure relief valve opening accidentally during the injection process, avoiding the risks of insufficient expansion of the elastic diaphragm, failure of thermal resistance adjustment, and coolant contamination caused by leakage of heat-conducting liquid. The electromagnet independently controls the pressure relief valve core, enabling the controller to actively open the pressure relief valve for liquid drainage. In conjunction with the wedge-shaped pressure boosting layer, it achieves bidirectional active adjustment of thermal resistance. Overall, this linkage-type liquid inlet self-locking valve group solves the safety timing problem of liquid injection and pressure relief through a purely mechanical interlocking method. This gives the variable thermal resistance heat conduction device a comprehensive advantage of reliable liquid injection, stable locking, controllable liquid drainage, and zero power consumption maintenance, providing a safe, stable, and efficient core component for thermal resistance adjustment in the battery thermal management system.

[0031] Preferably, both the outlet of the inlet pipe and the outlet of the pressure relief pipe are provided with limiting plates, the limiting plates are provided with guide holes, the inlet valve core and the limiting plate are provided with an inlet compression spring, and the pressure relief valve core and the limiting plate are provided with a pressure relief compression spring.

[0032] This invention achieves automatic reset and buffer limiting of the valve core by setting limiting plates with guide holes and compression springs at the liquid outlets of the inlet and pressure relief pipes. The inlet compression spring automatically closes the inlet valve core after the micro piston pump stops working, preventing backflow of the heat-conducting liquid. The pressure relief compression spring automatically resets the pressure relief valve core after the electromagnet is closed, ensuring reliable sealing of the pressure relief pipeline. The limiting plate serves as both a support for the springs and ensures smooth liquid flow through the guide holes. The compact structure and integrated functions enable the valve assembly to have self-locking characteristics, locking upon power failure and closing upon pump stoppage, maintaining a sealed state without continuous energy consumption.

[0033] Preferably, both the inlet valve core and the pressure relief valve core are cone-shaped bodies with gradually decreasing diameters. The small-diameter end of the inlet valve core faces the inlet of the inlet pipe, and the small-diameter end of the pressure relief valve core faces the outlet of the pressure relief pipe facing the inlet pipe.

[0034] Preferably, the electromagnet is fixed to the side wall of the pressure relief pipe, and a connecting rod is fixed to the large-diameter end of the pressure relief valve core. The end of the connecting rod protrudes from the side wall of the pressure relief pipe. A metal or rubber corrugated pipe or flexible sleeve is used, with one end welded or bonded to the outer wall of the groove and the other end fixed to the extended end of the connecting rod, so as to completely wrap the entire movement path of the rod and perform dynamic sealing.

[0035] A method for controlling the thermal management of batteries in pure electric commercial vehicles includes the following steps: S1: Parameter Acquisition and Status Recognition. Acquire the current operating status parameters of the battery and the status parameters of the thermal management system. The battery operating status parameters include at least the battery state of charge (SOC), real-time battery temperature, battery operating current, and battery operating rate. The thermal management system status parameters include at least the compressor operating status, coolant circulation capacity, and parameters characterizing heat exchange capacity. The parameters characterizing heat exchange capacity include one or more of the following: heat exchanger inlet and outlet temperatures, coolant flow rate, heat exchange temperature difference, or heat exchange efficiency. Identify whether the power battery is currently in a charging or discharging state. S2: Temperature change trend prediction. Based on the battery operating state parameters, a battery temperature trend prediction model is constructed, and temperature trend prediction results are generated. The trend prediction includes macro-trend prediction and fine-grained trend prediction. The macro trend prediction is as follows: when the battery is in a discharging state and the SOC is lower than the set threshold, it is predicted that there is a possibility of entering the charging state during subsequent operation, and the battery temperature will show an upward trend in the future; when the battery is in a charging state and the SOC is higher than the set threshold, it is predicted that there is a possibility of stopping charging during subsequent operation, and the battery temperature will show a downward trend in the future, thus forming a macro trend prediction of battery temperature changes within the first time window in the future. The fine trend prediction is as follows: based on the real-time battery temperature, battery operating current, and battery operating rate, a battery thermal balance model is used to make a fine trend prediction of the battery temperature change within a future second time window, wherein the first time window is larger than the second time window. Furthermore, by assessing the maximum cooling or heating power that the thermal management system can currently provide, and by comprehensively comparing this capability with the battery heating trend, the results of the macro-trend prediction and the fine-grained trend prediction are corrected. S3: Layered autonomous control of the thermal management system. Based on the corrected temperature trend prediction results, layered autonomous control is implemented on the thermal management system; the layered autonomous control includes long-term control strategies and short-term control strategies. The long-term adjustment strategy is as follows: dynamically adjust the battery temperature control threshold according to the macro trend prediction results; when the battery is in a discharging state and the SOC decreases, gradually reduce the battery temperature control target value to keep the battery in a lower temperature range and reserve temperature margin for the subsequent charging process; when the battery is in a charging state and the SOC increases, gradually increase the battery temperature control target value or reduce the cooling power to reduce unnecessary energy consumption. The short-term adjustment strategy is as follows: based on the fine trend prediction results, the compressor speed, coolant circulation flow rate or fan speed are dynamically adjusted, and the thermal resistance of the variable thermal resistance heat conduction device is adjusted in coordination, so that the cooling or heating capacity of the thermal management system matches the actual heat generation of the battery, thereby achieving fine control of the battery temperature. S4, Temperature Stability Maintenance: Relying on the predictive active temperature control, the power battery temperature is stably maintained within a suitable operating range, reducing temperature fluctuations and frequent start-stop of thermal management actuators, thereby improving battery life and vehicle energy utilization efficiency.

[0036] The short-term adjustment strategy involves bidirectional active adjustment of the thermal resistance of the variable thermal resistance heat conduction device, specifically including: S1, Enhanced Heat Dissipation Mode, when a future increase in battery temperature is predicted: The variable thermal resistance heat conduction device controls the movement of the wedge-shaped pressure boosting layer to increase the contact pressure between the liquid cooling plate and the battery cell, thereby reducing the contact thermal resistance. Simultaneously, the variable thermal resistance heat conduction device controls the hydraulic equalization layer to actively inject heat-conducting liquid into the sealed cavity, causing the elastic diaphragm to expand and tightly adhere to the bottom surface of the battery cell, further reducing the interface contact thermal resistance. The liquid pressure in the sealed cavity is monitored in real time, and the injection stops when the pressure reaches the preset maximum safety value. S2, Reduced heat dissipation mode, when it is predicted that the battery temperature will decrease in the future: The controller controls the movement of the wedge-shaped pressure-boosting layer in the variable thermal resistance heat conduction device to reduce the contact pressure between the liquid cooling plate and the battery cell, thereby increasing the contact thermal resistance. Simultaneously, the controller actively opens the pressure relief valve core, allowing the heat-conducting liquid in the sealed cavity to flow back to the storage tank. The elastic diaphragm actively contracts and resets, further increasing the interfacial thermal resistance and reducing heat transfer to the liquid cooling plate. When the pressure in the sealed cavity is detected to drop to a preset minimum value, the controller closes the pressure relief valve core, stopping the drainage. S4, Steady-state maintenance mode: When the battery temperature is predicted to remain stable in the future: the wedge-shaped pressure boosting layer in the variable thermal resistance heat conduction device is controlled to maintain its current position, so that the liquid cooling plate and the battery cell maintain the current contact pressure; the liquid injection action is turned off, the pressure relief valve core is closed, and the volume of heat-conducting liquid in the sealed cavity remains unchanged, maintaining the current thermal resistance; through the coordinated bidirectional adjustment of the wedge-shaped pressure boosting layer and the hydraulic pressure equalization layer, the active increase and active decrease of thermal resistance are realized, so that the thermal management system has a complete bidirectional thermal resistance adjustment capability.

[0037] This invention achieves early prediction of battery temperature changes by constructing a macroscopic and fine-grained dual-layer temperature trend prediction model and modifying it with the control capabilities of the thermal management system. Based on this, a layered autonomous control strategy combining long-term and short-term windows is adopted: the long-term strategy dynamically adjusts the temperature control threshold based on the State of Charge (SOC), reserving a temperature margin for transitions between charge and discharge conditions; the short-term strategy coordinates the adjustment of active temperature control components such as the compressor, water pump, and fan with the variable thermal resistance heat conduction device, achieving bidirectional active adjustment of thermal resistance. This method transforms traditional reactive control into predictive active control, significantly reducing battery temperature fluctuations and frequent start-stop cycles of actuators such as the compressor, extending battery cycle life and system reliability. Simultaneously, by matching thermal resistance as needed, it reduces the energy consumption of the thermal management system and improves the overall vehicle energy utilization efficiency.

[0038] In summary, the beneficial effects of this invention are as follows: 1. This invention constructs a two-layer prediction model that combines macro-trend prediction based on SOC (State of Charge) with fine-grained trend prediction based on real-time temperature, current, and rate capability. It also incorporates the temperature control capability of the thermal management system for correction, enabling early prediction of battery temperature change direction. Based on this, a layered autonomous control strategy combining long-term and short-term windows is adopted, transforming the thermal management system from a traditional reactive response to predictive active control. This effectively reduces battery temperature fluctuations, keeps the battery stable within its suitable operating range over the long term, slows cell material aging, and extends battery cycle life.

[0039] 2. This invention achieves stable regulation of cooling or heating power through the coordinated use of a long-term strategy (dynamically adjusting the temperature control threshold based on SOC) and a short-term strategy (coordinated adjustment of the compressor, water pump, fan, and variable thermal resistance heat conduction device). The variable thermal resistance heat conduction device undertakes part of the temperature regulation task, reducing the dependence on and impact on active temperature control components such as the compressor, reducing mechanical wear caused by frequent start-stop, and improving the operational reliability and component lifespan of the thermal management system.

[0040] 3. This invention achieves active, bidirectional, and real-time adjustment of the thermal resistance between the liquid cooling plate and the battery cell through the coordinated operation of the wedge-shaped pressure-boosting layer and the hydraulic pressure-equalizing layer. When a temperature rise is predicted, the wedge lifts the liquid cooling plate to increase the contact pressure, while the hydraulic pressure-equalizing layer injects liquid to expand the elastic diaphragm and adhere it to the bottom surface of the battery cell, significantly reducing the thermal resistance within seconds and filling the time vacuum period of coolant circulation. When a temperature drop is predicted, the wedge retracts to reduce the contact pressure, and the pressure relief valve core actively drains liquid to cause the elastic diaphragm to contract and reset, effectively increasing the thermal resistance and providing heat preservation. This on-demand adjustment mode, which allows for unobstructed flow when heat dissipation is needed and blocked when heat preservation is needed, avoids the energy waste of a fixed thermal resistance structure under low-heat conditions and the insufficient heat dissipation under high-heat conditions, significantly improving the energy efficiency of the thermal management system.

[0041] 4. This invention features an independent hydraulic equalization layer beneath each battery cell, allowing for independent adjustment of the thermal resistance between each cell and the liquid cooling plate. The thermal management system can allocate heat according to the actual heating state of each cell, reducing thermal resistance and enhancing heat dissipation for cells with high heat generation, while increasing thermal resistance and reducing heat dissipation for cells with low heat generation. This solves the coupling dilemma in traditional solutions where all cells suffer the same fate. At the same time, the expansion and bonding of the elastic diaphragm effectively fills the microscopic unevenness on the bottom surface of the cells, eliminating the problem of inconsistent contact thermal resistance caused by individual differences, and significantly improving the overall temperature uniformity of the battery pack. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the method of the present invention; Figure 2 This is an overall schematic diagram of the variable thermal resistance heat conduction device of the present invention; Figure 3 This is a three-dimensional schematic diagram of the wedge-shaped pressure-increasing layer of the present invention; Figure 4 This is a schematic diagram of the hydraulic pressure equalization layer of the present invention; Figure 5 This is a cross-sectional schematic diagram of the hydraulic pressure equalization layer of the present invention; Figure 6 This is a cross-sectional schematic diagram of the linkage-type liquid inlet self-locking valve assembly of the present invention; Figure 7 This is a cross-sectional schematic diagram showing the locking of the pressure relief valve core of the linkage-type liquid inlet self-locking valve assembly of the present invention; Figure 8 This is a cross-sectional schematic diagram of the pressure relief valve core of the linkage liquid inlet self-locking valve group of the present invention being opened; Figure 9 This is the present invention. Figure 8 An enlarged schematic diagram of point A. Detailed Implementation

[0043] The following specific embodiments are merely illustrative of the present invention and are not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present invention.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] Example: Figure 2 As shown, a variable thermal resistance heat conduction device includes a liquid cooling plate 1, a battery cell 2, a wedge pressure boosting layer 3, and a hydraulic pressure equalization layer 5. The liquid cooling plate 1 is located below the battery cell 2, the wedge pressure boosting layer 3 is located below the liquid cooling plate 1, and the hydraulic pressure equalization layer 5 is located between the upper surface of the liquid cooling plate 1 and the battery cell 2.

[0046] like Figure 3 As shown, the wedge-shaped pressure boosting layer 3 includes a wedge pusher 31, a roller 32, an electric push rod 33, and a fixing plate 34. The motor end of the electric push rod 33 is fixed on the fixing plate 34, and the push rod end of the electric push rod 33 is fixedly connected to the wedge pusher 31. The roller 32 is rotatably disposed below the liquid cooling plate 1, so that when the wedge pusher 31 moves horizontally, the roller 32 pushes the liquid cooling plate 1 upward.

[0047] like Figures 4-5 As shown, each battery cell 2 has a hydraulic equalization layer 5 below it. The hydraulic equalization layer 5 includes a sealing frame 51, an elastic diaphragm 52, and a hydraulic control system 53. The elastic diaphragm 52 is pressed inside the sealing frame 51 to form a sealed cavity 54 with the top of the liquid cooling plate 1. The sealed cavity 54 is filled with a heat-conducting liquid 541. The hydraulic equalization layer 5 is used to control the injection and discharge of the heat-conducting liquid 541, causing the elastic diaphragm 52 to expand and fill the bottom surface of the battery cell 2. To address microscopic unevenness or shrinkage and reset, the hydraulic control system 53 includes a miniature piston pump 531, a linked liquid inlet self-locking valve assembly 55, and a pressure sensor. The linked liquid inlet self-locking valve assembly 55 is equipped with an inlet pipe 551, a pressure relief pipe 552, and an access pipe 553. The miniature piston pump 531 is connected to the inlet pipe 551 of the linked liquid inlet self-locking valve assembly 55 via a pipeline. The access pipe 553 is connected to the inlet of the sealed cavity 54. The pressure relief pipe 552 is connected to a storage tank via a pipeline. The pressure sensor is located at the outlet of the sealed cavity 54, monitoring the liquid pressure in real time and feeding it back to the controller.

[0048] like Figures 6-9As shown, the linkage-type liquid inlet self-locking valve assembly 55 includes a valve seat 551, a liquid inlet valve core 552, a pressure relief valve core 553, a linkage rod 554, an upper baffle 555, an upper push rod 556, a lower baffle 557, a lower push rod 558, and an electromagnet 550. The liquid inlet pipe 551, the pressure relief pipe 552, and the connecting pipe 553 are disposed on the valve seat 551. The liquid inlet pipe 551 is provided with a liquid inlet groove 559, and the liquid inlet valve core 552 is slidably disposed on the liquid inlet groove 559. The pressure relief pipe 552 is provided with a pressure relief groove 5501, and the pressure relief valve core 553 is slidably disposed on the pressure relief groove 5501. The linkage rod 554 is disposed on the back of the liquid inlet valve core 552. The upper push rod 556 and the lower push rod 557 are connected to the upper baffle 558. Push rod 558 is fixed on both sides of linkage rod 554 and passes through the groove wall of pressure relief groove 5501. The upper baffle 555 and lower baffle 557 are rotatably mounted at the groove opening of pressure relief groove 5501 with the middle as the center, so that when the upper push rod 556 and lower push rod 558 are pushed out, they can drive the upper baffle 555 and lower baffle 557 to rotate and abut against pressure relief valve core 553. The electromagnet 550 controls the movement of pressure relief valve core 553. Limiting plates 5551 are provided on the outlet of liquid inlet pipe 551 and the outlet of pressure relief pipe 552. The limiting plates 5551 are provided with guide holes 5552. An inlet compression spring 561 is provided between the inlet valve core 552 and the limiting plate 5551. A pressure relief compression spring 562 is provided between the pressure relief valve core 553 and the limiting plate 5551. Both the liquid inlet valve core 552 and the pressure relief valve core 553 are cone-shaped bodies with gradually decreasing diameters. The small diameter end of the liquid inlet valve core 552 faces the liquid inlet of the liquid inlet pipe 551, and the small diameter end of the pressure relief valve core 553 faces the liquid outlet of the pressure relief pipe 552 and the liquid inlet pipe 551. The electromagnet 550 is fixed on the side wall of the pressure relief pipe 552. A connecting rod 5501 is fixed to the large diameter end of the pressure relief valve core 553, and the end of the connecting rod 5501 protrudes from the side wall of the pressure relief pipe 552.

[0049] like Figure 1 As shown, a method for controlling the thermal management of a battery in a pure electric commercial vehicle includes the following steps: S1: Parameter Acquisition and Status Recognition. Acquire the current operating status parameters of the battery and the status parameters of the thermal management system. The battery operating status parameters include at least the battery state of charge (SOC), real-time battery temperature, battery operating current, and battery operating rate. The thermal management system status parameters include at least the compressor operating status, coolant circulation capacity, and parameters characterizing heat exchange capacity. The parameters characterizing heat exchange capacity include one or more of the following: heat exchanger inlet and outlet temperatures, coolant flow rate, heat exchange temperature difference, or heat exchange efficiency. Identify whether the power battery is currently in a charging or discharging state. S2: Temperature change trend prediction. Based on the battery operating state parameters, a battery temperature trend prediction model is constructed, and temperature trend prediction results are generated. The trend prediction includes macro-trend prediction and fine-grained trend prediction. The macro trend prediction is as follows: when the battery is in a discharging state and the SOC is lower than the set threshold, it is predicted that there is a possibility of entering the charging state during subsequent operation, and the battery temperature will show an upward trend in the future; when the battery is in a charging state and the SOC is higher than the set threshold, it is predicted that there is a possibility of stopping charging during subsequent operation, and the battery temperature will show a downward trend in the future, thus forming a macro trend prediction of battery temperature changes within the first time window in the future. The fine trend prediction is as follows: based on the real-time battery temperature, battery operating current, and battery operating rate, a battery thermal balance model is used to make a fine trend prediction of the battery temperature change within a future second time window, wherein the first time window is larger than the second time window. The battery thermal balance model is based on the balance equation between the battery's heat generation power Q = I²R + IT(dE / dT) and heat dissipation power. It combines the current coolant flow rate and ambient temperature parameters to solve for the temperature change curve within the second time window Δt2. Here, Q is the battery's heat generation power, I is the battery's operating current, R is the battery's equivalent internal resistance, T is the battery's real-time temperature, E is the battery's open-circuit voltage, and dE / dT is the open-circuit voltage temperature coefficient. The heat dissipation power is calculated based on the convective heat transfer coefficient between the coolant and the battery, the effective heat transfer area, and the current temperature difference.

[0050] Furthermore, by assessing the maximum cooling or heating power that the thermal management system can currently provide, and by comprehensively comparing this capability with the battery heating trend, the results of the macro-trend prediction and the fine-grained trend prediction are corrected. S3: Layered autonomous control of the thermal management system. Based on the corrected temperature trend prediction results, layered autonomous control is implemented on the thermal management system; the layered autonomous control includes long-term control strategies and short-term control strategies. The long-term adjustment strategy is as follows: dynamically adjust the battery temperature control threshold according to the macro trend prediction results; when the battery is in a discharging state and the SOC decreases, gradually reduce the battery temperature control target value to keep the battery in a lower temperature range and reserve temperature margin for the subsequent charging process; when the battery is in a charging state and the SOC increases, gradually increase the battery temperature control target value or reduce the cooling power to reduce unnecessary energy consumption. The short-term adjustment strategy is as follows: based on the fine trend prediction results, the compressor speed, coolant circulation flow rate or fan speed are dynamically adjusted, and the thermal resistance of the variable thermal resistance heat conduction device is adjusted in coordination, so that the cooling or heating capacity of the thermal management system matches the actual heat generation of the battery, thereby achieving fine control of the battery temperature. S4, Temperature Stability Maintenance: Relying on the predictive active temperature control, the power battery temperature is stably maintained within a suitable operating range, reducing temperature fluctuations and frequent start-stop of thermal management actuators, thereby improving battery life and vehicle energy utilization efficiency.

[0051] The short-term adjustment strategy involves bidirectional active adjustment of the thermal resistance of the variable thermal resistance heat conduction device, specifically including: S1, Enhanced Heat Dissipation Mode, when a future increase in battery temperature is predicted: The variable thermal resistance heat conduction device controls the movement of the wedge-shaped pressure-boosting layer 3 to increase the contact pressure between the liquid cooling plate 1 and the battery cell 2, thereby reducing the contact thermal resistance. Simultaneously, the variable thermal resistance heat conduction device controls the hydraulic equalization layer 5 to actively inject heat-conducting liquid 541 into the sealed cavity 54, causing the elastic diaphragm 52 to expand and tightly adhere to the bottom surface of the battery cell 2, further reducing the interface contact thermal resistance. The liquid pressure in the sealed cavity 54 is monitored in real time, and the injection stops when the pressure reaches the preset maximum safety value. S2, Reduced heat dissipation mode, when it is predicted that the battery temperature will decrease in the future: The controller controls the operation of the wedge-shaped pressure-boosting layer 3 in the variable thermal resistance heat conduction device to reduce the contact pressure between the liquid cooling plate 1 and the battery cell 2, thereby increasing the contact thermal resistance. At the same time, the controller actively opens the pressure relief valve core 553, allowing the heat-conducting liquid 541 in the sealed cavity 54 to flow back to the storage tank. The elastic diaphragm 52 actively contracts and resets, further increasing the interface thermal resistance and reducing the transfer of heat to the liquid cooling plate 1. When the pressure in the sealed cavity 54 is detected to drop to a preset minimum value, the controller closes the pressure relief valve core 553 to stop the liquid discharge. S3, Steady-state maintenance mode: When the battery temperature is predicted to remain stable in the future: the wedge-shaped pressure boosting layer 3 in the variable thermal resistance heat conduction device is controlled to maintain its current position, so that the liquid cooling plate 1 and the battery cell 2 maintain the current contact pressure; the liquid injection action is turned off, and the volume of the heat-conducting liquid 541 in the sealed cavity 54 remains unchanged, maintaining the current thermal resistance; through the coordinated bidirectional adjustment of the wedge-shaped pressure boosting layer 3 and the hydraulic pressure equalizing layer 5, the active increase and active decrease of the thermal resistance are realized, so that the thermal management system has a complete bidirectional thermal resistance adjustment capability.

[0052] Working principle: First, macro-trend prediction is made based on the battery's SOC. When discharging, the system predicts temperature rise when the SOC is low and temperature drop when charging when the SOC is high. At the same time, fine-grained trend prediction is made based on real-time temperature, current, and rate, and the current cooling and heating capacity of the thermal management system is evaluated and corrected. Then, based on the prediction results, tiered control is implemented. The long-term strategy dynamically adjusts the temperature control threshold according to the SOC. During discharge, the target temperature is gradually reduced to reserve margin for subsequent charging. During charging, the target temperature is gradually increased or the cooling power is reduced to reduce energy consumption. The short-term strategy adjusts the power of the main circuit such as the compressor, water pump, and fan on the one hand, and coordinates the adjustment of the variable thermal resistance heat conduction device on the other hand.

[0053] The specific working process of the variable thermal resistance heat conduction device is as follows: When the predicted temperature rise requires enhanced heat dissipation, the controller controls the electric push rod 33 to extend, pushing the inclined wedge push block 31 to move horizontally. Its inclined surface cooperates with the roller 32 to convert the horizontal thrust into a vertical upward lifting force, causing the liquid cooling plate 1 to lift upward, increasing the contact pressure with the battery cell 2 and reducing the contact thermal resistance. At the same time, the controller starts the micro piston pump 531, and the heat conduction liquid 541 pushes the inlet valve core 552 to open through the inlet pipe 551 and the inlet tank 559, entering the sealed cavity 54. The elastic diaphragm 52 expands and tightly adheres to the battery cell 2. The bottom surface of cell 2 is filled with microscopic unevenness to further reduce interfacial thermal resistance. During the liquid injection process, the linkage rod 554 on the back of the liquid inlet valve core 552 drives the upper and lower push rods 556 and 558 to extend, pushing the upper and lower baffles 555 and 557 to rotate and block the pressure relief valve core 553, locking it in the closed position to prevent the pressure relief valve from being opened accidentally due to vibration or pressure fluctuations. The pressure sensor monitors the pressure in the cavity in real time. When the preset maximum value is reached, the liquid injection stops, the liquid inlet compression spring 561 pushes the liquid inlet valve core 552 to close automatically, and the linkage rod 554 retracts to release the lock on the pressure relief valve core 553. When cooling is predicted and heat dissipation needs to be reduced, the controller retracts the electric push rod 33, the wedge push block 31 moves back, and the liquid cooling plate 1 descends under gravity, reducing contact pressure and increasing contact thermal resistance. Simultaneously, the controller activates the electromagnet 550, overcoming the elastic force of the pressure relief compression spring 562 to move the pressure relief valve core 553, opening the pressure relief passage. The heat-conducting liquid 541 flows back to the storage tank through the pressure relief pipe 552, and the elastic diaphragm 52 contracts and resets, further increasing the interfacial thermal resistance and reducing heat transfer to the liquid cooling plate 1. When the pressure sensor detects that the pressure inside the cavity has dropped to a preset minimum value, the controller deactivates the electromagnet 550, and the pressure relief compression spring 562 pushes the pressure relief valve core 553 to automatically reset and close the pressure relief passage. When the overpressure exceeds the tightening force of the pressure relief compression spring 562, the pressure relief valve core 553 automatically opens to drain the liquid. Each battery cell 2 is equipped with an independent hydraulic equalization layer 5, which can independently adjust the thermal resistance between a single cell and the liquid cooling plate, so as to realize the on-demand allocation of heat dissipation by reducing resistance for hot cells and heat preservation by increasing resistance for cold cells. In steady state, the electric push rod 33 remains in its current position, the micro piston pump 531 and the electromagnet 550 are both turned off, the liquid volume in the sealed cavity 54 is locked, and the thermal resistance remains unchanged.

[0054] Through the aforementioned "predictive + hierarchical + collaborative" control mode, the thermal management system is transformed from a passive response to predictive active control, achieving refined and stable management of battery temperature.

Claims

1. A variable thermal resistance heat conduction device, characterized in that, It includes a liquid cooling plate (1), a battery cell (2), a wedge pressure boosting layer (3), and a hydraulic equalization layer (5). The liquid cooling plate (1) is located below the battery cell (2), the wedge pressure boosting layer (3) is located below the liquid cooling plate (1), and the hydraulic equalization layer (5) is located between the upper surface of the liquid cooling plate (1) and the battery cell (2).

2. The variable thermal resistance heat conduction device according to claim 1, characterized in that, The wedge pressurization layer (3) includes a wedge pusher (31), a roller (32), an electric pusher (33), and a fixing plate (34). The motor end of the electric pusher (33) is fixed on the fixing plate (34), and the pusher end of the electric pusher (33) is fixedly connected to the wedge pusher (31). The roller (32) is rotatably located below the liquid cooling plate (1), so that when the wedge pusher (31) moves horizontally, the roller (32) pushes the liquid cooling plate (1) upward.

3. The variable thermal resistance heat conduction device according to claim 1, characterized in that, Each battery cell (2) is provided with a hydraulic equalization layer (5) below it. The hydraulic equalization layer (5) includes a sealing frame (51), an elastic diaphragm (52) and a hydraulic control system (53). The elastic diaphragm (52) is pressed inside the sealing frame (51) and forms a sealed cavity (54) with the top of the liquid cooling plate (1). The sealed cavity (54) is filled with a heat-conducting liquid (541). The hydraulic equalization layer (5) is used to control the injection and discharge of the heat-conducting liquid (541) so that the elastic diaphragm (52) expands to fill the microscopic unevenness of the bottom surface of the battery cell (2) or contracts to reset.

4. The variable thermal resistance heat conduction device according to claim 1, characterized in that, The hydraulic control system (53) includes a miniature piston pump (531), a linkage-type liquid inlet self-locking valve group (55), and a pressure sensor. The linkage-type liquid inlet self-locking valve group (55) is provided with an inlet pipe (551), a pressure relief pipe (552), and an access pipe (553). The miniature piston pump (531) is connected to the inlet pipe (551) of the linkage-type liquid inlet self-locking valve group (55) via a pipeline. The access pipe (553) is connected to the inlet of the sealed cavity (54). The pressure sensor is set on the outlet of the sealed cavity (54) to monitor the liquid pressure in real time and feed it back to the controller.

5. A variable thermal resistance heat conduction device according to claim 4, characterized in that, The linkage-type liquid inlet self-locking valve assembly (55) includes a valve seat (551), a liquid inlet valve core (552), a pressure relief valve core (553), a linkage rod (554), an upper baffle (555), an upper push rod (556), a lower baffle (557), a lower push rod (558), and an electromagnet (550). The liquid inlet pipe (551), the pressure relief pipe (552), and the connecting pipe (553) are located on the valve seat (551). The liquid inlet pipe (551) is provided with a liquid inlet groove (559), and the liquid inlet valve core (552) is slidably located on the liquid inlet groove (559). The pressure relief pipe (552) is provided with a pressure relief groove (5501), and the pressure relief valve core (554) is located on the connecting rod (555). 3) It can be slidably mounted on the pressure relief groove (5501). The linkage rod (554) is located on the back of the liquid inlet valve core (552). The upper push rod (556) and the lower push rod (558) are fixed on both sides of the linkage rod (554) and pass through the groove wall of the pressure relief groove (5501). The upper baffle (555) and the lower baffle (557) are rotatably mounted on the groove opening of the pressure relief groove (5501) with the middle as the center. When the upper push rod (556) and the lower push rod (558) are pushed out, they can drive the upper baffle (555) and the lower baffle (557) to rotate and abut against the pressure relief valve core (553). The electromagnet (550) controls the movement of the pressure relief valve core (553).

6. A variable thermal resistance heat conduction device according to claim 5, characterized in that, Both the outlet of the inlet pipe (551) and the outlet of the pressure relief pipe (552) are provided with limiting plates (5551), and the limiting plates (5551) are provided with guide holes (5552). An inlet compression spring (561) is provided between the inlet valve core (552) and the limiting plate (5551), and a pressure relief compression spring (562) is provided between the pressure relief valve core (553) and the limiting plate (5551).

7. A variable thermal resistance heat conduction device according to claim 5, characterized in that, Both the inlet valve core (552) and the pressure relief valve core (553) are cone-shaped bodies with gradually decreasing diameters. The small diameter end of the inlet valve core (552) faces the inlet of the inlet pipe (551), and the small diameter end of the pressure relief valve core (553) faces the outlet of the pressure relief pipe (552) towards the inlet pipe (551).

8. A variable thermal resistance heat conduction device according to claim 7, characterized in that, The electromagnet (550) is fixed on the side wall of the pressure relief pipe (552), and the large-diameter end of the pressure relief valve core (553) is fixed with a connecting rod (5501), the end of which protrudes from the side wall of the pressure relief pipe (552).

9. A method for thermal management control of a battery in a pure electric commercial vehicle, characterized in that, Includes the following steps: S1: Parameter Acquisition and Status Recognition. Acquire the current operating status parameters of the battery and the status parameters of the thermal management system. The battery operating status parameters include at least the battery state of charge (SOC), real-time battery temperature, battery operating current, and battery operating rate. The thermal management system status parameters include at least the compressor operating status, coolant circulation capacity, and parameters characterizing heat exchange capacity. The parameters characterizing heat exchange capacity include one or more of the following: heat exchanger inlet and outlet temperatures, coolant flow rate, heat exchange temperature difference, or heat exchange efficiency. Identify whether the power battery is currently in a charging or discharging state. S2: Temperature change trend prediction. Based on the battery operating state parameters, a battery temperature trend prediction model is constructed, and temperature trend prediction results are generated. The trend prediction includes macro-trend prediction and fine-grained trend prediction. The macro trend prediction is as follows: when the battery is in a discharging state and the SOC is lower than the set threshold, it is predicted that there is a possibility of entering the charging state during subsequent operation, and the battery temperature will show an upward trend in the future; when the battery is in a charging state and the SOC is higher than the set threshold, it is predicted that there is a possibility of stopping charging during subsequent operation, and the battery temperature will show a downward trend in the future, thus forming a macro trend prediction of battery temperature changes within the first time window in the future. The fine trend prediction is as follows: based on the real-time battery temperature, battery operating current, and battery operating rate, a battery thermal balance model is used to make a fine trend prediction of the battery temperature change within a future second time window, wherein the first time window is larger than the second time window. Furthermore, by assessing the maximum cooling or heating power that the thermal management system can currently provide, and by comprehensively comparing this capability with the battery heating trend, the results of the macro-trend prediction and the fine-grained trend prediction are corrected. S3: Layered autonomous control of the thermal management system. Based on the corrected temperature trend prediction results, the thermal management system is subject to layered autonomous control. The tiered autonomous regulation includes long-term and short-term adjustment strategies: The long-term adjustment strategy is as follows: dynamically adjust the battery temperature control threshold according to the macro trend prediction results; when the battery is in a discharging state and the SOC decreases, gradually reduce the battery temperature control target value to keep the battery in a lower temperature range and reserve temperature margin for the subsequent charging process; when the battery is in a charging state and the SOC increases, gradually increase the battery temperature control target value or reduce the cooling power to reduce unnecessary energy consumption. The short-term adjustment strategy is as follows: based on the fine trend prediction results, the compressor speed, coolant circulation flow rate or fan speed are dynamically adjusted, and the thermal resistance of the variable thermal resistance heat conduction device is adjusted in coordination, so that the cooling or heating capacity of the thermal management system matches the actual heat generation of the battery, thereby achieving fine control of the battery temperature. S4, Temperature Stability Maintenance: Relying on the predictive active temperature control, the power battery temperature is stably maintained within a suitable operating range, reducing temperature fluctuations and frequent start-stop of thermal management actuators, thereby improving battery life and vehicle energy utilization efficiency.

10. A method for controlling the thermal management of a battery in a pure electric commercial vehicle according to claim 9, characterized in that, The short-term adjustment strategy involves bidirectional active adjustment of the thermal resistance of the variable thermal resistance heat conduction device, specifically including: S1, Enhanced Heat Dissipation Mode, when a future increase in battery temperature is predicted: The wedge-shaped pressure boosting layer (3) in the variable thermal resistance heat conduction device is controlled to increase the contact pressure between the liquid cooling plate (1) and the battery cell (2) and reduce the contact thermal resistance. At the same time, the hydraulic equalization layer (5) in the variable thermal resistance heat conduction device is controlled to actively inject heat-conducting liquid (541) into the sealed cavity (54), so that the elastic diaphragm (52) expands and tightly adheres to the bottom surface of the battery cell (2) to further reduce the interface contact thermal resistance. The liquid pressure in the sealed cavity (54) is monitored in real time, and the injection is stopped when the pressure reaches the preset maximum safety value. S2, Reduced heat dissipation mode, when it is predicted that the battery temperature will decrease in the future: The controller controls the operation of the wedge-shaped pressure boosting layer (3) in the variable thermal resistance heat conduction device to reduce the contact pressure between the liquid cooling plate (1) and the battery cell (2) and increase the contact thermal resistance. At the same time, the controller actively opens the pressure relief valve core (553) so that the heat conduction liquid (541) in the sealed cavity (54) flows back to the storage tank. The elastic diaphragm (52) actively contracts and resets, further increasing the interface thermal resistance and reducing the transfer of heat to the liquid cooling plate (1). When the pressure in the sealed cavity (54) is detected to drop to the preset minimum value, the controller closes the pressure relief valve core (553) and stops the liquid discharge. S3, steady-state maintenance mode, when it is predicted that the battery temperature will remain stable in the future: control the wedge pressure boosting layer (3) in the variable thermal resistance heat conduction device to maintain the current position, so that the liquid cooling plate (1) and the battery cell (2) maintain the current contact pressure; close the liquid injection action, close the pressure relief valve core (553), and keep the volume of the heat conduction liquid (541) in the sealed cavity (54) unchanged, maintaining the current thermal resistance; through the coordinated bidirectional adjustment of the wedge pressure boosting layer (3) and the hydraulic equalization layer (5), the active increase and active decrease of thermal resistance are realized, so that the thermal management system has a complete bidirectional thermal resistance adjustment capability.

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