Electric vehicle integrated heat management system based on fused salt composite heat storage material

Abstract

The invention discloses an electric vehicle integrated heat management system based on a fused salt composite heat storage material, and relates to the technical field of electric vehicle heat management. Comprising an equipment heat management module used for carrying out heat regulation and control on electric vehicle components; the composite material heat exchange module is used for adjusting the flow direction and the circulation mode of the cooling liquid according to the temperature change of the fused salt composite heat storage material; the air conditioning module is used for heating or cooling air or cooling liquid in a closed environment; and the control module is used for constructing an optimal control strategy based on the minimum value principle and controlling the equipment heat management module, the air conditioner module and the composite material heat exchange module according to the optimal control strategy. Waste heat which is difficult to effectively utilize in a traditional heat management system can be stored, the waste heat is reasonably distributed to parts needing to be heated according to the system operation state, and therefore direct consumption of electric energy of an electric automobile is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicle thermal management, and particularly relates to an integrated thermal management system for electric vehicles based on molten salt composite heat storage materials. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] At present, as the core energy unit of electric vehicles, the power battery pack will generate a large amount of heat in the frequent charging and discharging process. If the heat cannot be dissipated in time and effectively, the battery temperature will continue to rise, which will lead to the performance degradation and cycle life shortening of the battery, and even cause thermal runaway and safety hazards in severe cases. At the same time, in low temperature environment, the charging and discharging efficiency of the battery is significantly reduced, which not only affects the power output of the whole vehicle, but also shortens the cruising range. Therefore, it is necessary to stabilize the working temperature of the battery pack in the appropriate range of 20℃ to 45℃, so as to ensure its performance, safety and service life.

[0004] In addition, the driving motor and the gearbox will also generate heat due to the loss of energy conversion efficiency during operation. The optimal working temperature of these components is generally around 90℃. If the heat dissipation is insufficient, it will easily lead to efficiency reduction, unstable operation, and even equipment failure. Therefore, efficient thermal management is also needed for these components to ensure the reliability and durability of the whole vehicle system.

[0005] Although the current electric vehicle thermal management system generally uses air cooling or liquid cooling to control the temperature of the battery pack, driving motor and power electronic device and other key components, and tries to use the waste heat in the cooling liquid for battery heating or passenger cabin heating, there are still many technical bottlenecks. First of all, the existing system generally has low energy efficiency. Most of the thermal management structures use single cooling loop or independent heat dissipation mode, lack of systematic heat recovery and distribution mechanism, resulting in a large amount of waste heat being directly discharged, and low energy utilization efficiency. Secondly, the system has weak adaptability to complex working conditions. In the face of fast charging, high speed, severe cold, high temperature and other variable environments, the traditional thermal management system has a lag in response and regulation, and it is difficult to complete the temperature regulation in time, which easily leads to overheating or insufficient heating. In addition, the existing system has low integration, and the heat pump, battery thermal management, motor cooling and other subsystems are operated independently, lacking a unified heat energy management platform, which causes complex structure, equipment redundancy, difficult layout, increases the manufacturing and maintenance cost, and affects the stability and efficiency of the system.

[0006] During the operation of an electric vehicle, multiple key components such as power batteries, drive motors, power electronic devices and passenger cabins are involved in energy conversion and heat exchange, and if there is a lack of effective management, it will directly affect the safety, reliability and operating efficiency of the whole vehicle. Especially under complex working conditions such as fast charging, high speed, high and low temperature, a large amount of heat is generated and lost, and the existing system often cannot balance real-time response and energy efficiency optimization.

[0007] Therefore, it is urgent to develop a new type of electric vehicle thermal management and energy control integrated system with the advantages of high energy efficiency, multi-working condition adaptability and system integration, to realize efficient recovery, intelligent regulation and unified scheduling of thermal energy, and comprehensively improve the thermal management performance and energy utilization efficiency of the whole vehicle. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide an electric vehicle integrated thermal management system based on molten salt composite heat storage material, which can store the waste heat that cannot be effectively utilized in the traditional thermal management system, and reasonably distribute it to the components that need to be heated according to the system operating state, thereby reducing the direct consumption of electric energy by the electric vehicle.

[0009] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme: The present application provides an electric vehicle integrated thermal management system based on molten salt composite heat storage material, comprising: An equipment thermal management module for regulating the heat of electric vehicle components; A composite material heat exchange module for adjusting the flow direction and circulation mode of the cooling liquid according to the temperature change of the molten salt composite heat storage material; An air conditioning module for heating or cooling air or cooling liquid in a closed environment; A control module for constructing an optimal control strategy based on the minimum value principle, and controlling the equipment thermal management module, the air conditioning module and the composite material heat exchange module according to the optimal control strategy.

[0010] Further, the equipment thermal management module includes a motor thermal management module and a battery thermal management module, the motor thermal management module is used for heat exchange with the composite material heat exchange module through the flow of cooling liquid according to the temperature of the motor, and the battery thermal management module is used for heat exchange with the composite material heat exchange module through the flow of cooling liquid according to the temperature of the battery.

[0011] Still further, the battery thermal management module includes a second water pump, a battery water cooling coil and a second expansion water kettle connected in series, and the motor thermal management module includes a third water pump, a motor water cooling coil and a third expansion water kettle connected in series.

[0012] Further, the motor water cooling coil is connected with the battery water cooling coil, and the second water pump and the third water pump are connected.

[0013] Further, the composite heat exchange module comprises a thermostat, a first water pump, a first expansion water kettle, a molten salt composite heat storage material heat exchanger, a heat pump compressor, a radiator, a reversing valve and a proportional flow valve, wherein one end of the molten salt composite heat storage material heat exchanger is connected with the proportional flow valve, the other end of the proportional flow valve is connected with the reversing valve, the heat pump compressor, the outlet of the thermostat bypass valve and the outlet of the radiator, the outlet of the main valve of the thermostat is connected with the inlet of the radiator, the inlet of the main valve of the thermostat is connected with the outlet of the first water pump, and the inlet of the radiator is connected with the inlet of the molten salt composite heat storage material heat exchanger.

[0014] Further, the composite heat exchange module further comprises a three-way valve and a two-way valve, the other end of the molten salt composite heat storage material heat exchanger is connected with the three-way valve, the other end of the three-way valve is connected with the two-way valve and the outlet of the in-cabin heat exchanger, and the two-way valve is connected with the inlet of the first water pump.

[0015] Further, the air conditioning module comprises an air conditioning fan, an in-cabin heat exchanger, a reversing valve and an out-cabin heat exchanger, and the in-cabin heat exchanger, the reversing valve and the out-cabin heat exchanger are connected in series.

[0016] Further, the motor thermal management module and the battery thermal management module are connected in parallel, and the motor thermal management module and the battery thermal management module connected in parallel are connected in series with the molten salt composite heat exchanger.

[0017] Further, the composite material in the composite heat exchange module is a nitrate molten salt composite heat storage material.

[0018] Further, in the control module, the specific steps of constructing the optimal control strategy based on the minimum value principle are as follows: Taking the power demand of the driving motor, the state of charge of the battery, the battery temperature, the motor temperature, the ambient temperature and the cooling liquid temperature as input variables, an optimization function with the minimum fuel consumption as the target is established, the engine power, the motor power and the battery charging and discharging power are adjusted in real time, the engine output power, the battery charging and discharging power and the motor load are dynamically adjusted, so as to realize the collaborative optimal control of energy distribution and thermal state.

[0019] The above one or more technical solutions have the following beneficial effects: The application discloses an integrated thermal management system for electric vehicles based on fused salt composite heat storage materials, which realizes efficient storage, recovery and regulation of thermal energy through the cooperative operation of multiple sub-modules, and improves the energy efficiency and thermal management performance of the whole vehicle. The system can introduce the waste heat generated by the motor module into the composite material heat exchange module or heat pump system for battery heating or passenger cabin heating, thereby improving the waste heat utilization rate and reducing the energy consumption of the whole vehicle. According to the vehicle operating state and thermal load demand, the heat flow path is dynamically adjusted to realize intelligent distribution of thermal energy and rapid response of the system. In combination with the energy control strategy based on the minimum principle (PMP), the application introduces the battery temperature as a control optimization variable into the ECMS (minimum fuel consumption strategy) optimization objective function, so that the high-temperature high-current discharge is inhibited, the battery aging is delayed, and the battery efficiency is improved through reasonable energy scheduling and auxiliary heating when necessary, while meeting the driving demand of the whole vehicle.

[0020] The application deeply integrates the thermal management system and the energy management system, proposes an optimization control method considering the battery temperature, and constructs an optimal control strategy based on the minimum principle (PMP). The strategy takes the vehicle driving power, the battery SOC, the battery temperature and the like as input variables, establishes an optimization function with fuel consumption as the target, dynamically adjusts the engine output power, the battery charging and discharging power and the motor load, so as to realize the collaborative optimal control of energy distribution and thermal state. The control system can effectively avoid the battery aging risk caused by high-temperature high-current work, and through reasonable scheduling of the working point of the controller, the battery temperature is improved through slight charging when necessary, so that the battery is always in the high-efficiency and safe working interval.

[0021] The application introduces a composite material heat exchange module, and through the selection of nitrate salt fused salt composite heat storage materials with different melting points, the multi-stage thermal energy absorption and release are realized. In the battery fast charging or motor high load working condition, the module can absorb and store the excess heat; in the low temperature environment, the heat is released to provide heating support for the battery or vehicle cabin.

[0022] The application realizes efficient recovery, storage and dynamic allocation of heat energy by introducing molten salt composite heat storage material for heat monitoring and regulation, significantly improving the overall energy efficiency and response capability of the thermal management system. The system can not only timely absorb excess heat under fast charging, high load and other working conditions, but also provide a continuous heat source for the battery or passenger cabin in a low temperature environment, reducing the direct heating dependence of the electric vehicle on its own electric energy, prolonging the endurance mileage, and avoiding energy waste and structural redundancy caused by independent operation of multiple subsystems in the existing thermal management system. In addition, the control module optimizes the heat flow path in real time according to the vehicle working condition and thermal load change, so that the system has good adaptability and regulation accuracy, and the overall structure is more compact, facilitating vehicle integration and maintenance, and has outstanding technical advantages and practical application value. At the same time, through the intelligent control module, the vehicle running state and thermal load change are sensed in real time, and the system can dynamically optimize the heat flow path and accurately adjust the heat energy distribution of each subsystem.

[0023] The advantages of the additional aspects of the application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0025] Figure 1 The framework diagram of the integrated thermal management system of the electric vehicle based on the molten salt composite heat storage material in the embodiment of the present application; Figure 2 The principle diagram of the optimal control strategy in the embodiment of the present application; Among them, 1, air conditioner fan, 2, thermostat, 3, first water pump, 4, two-way valve, 5, first expansion water kettle, 6, three-way valve, 7, molten salt composite heat storage material heat exchanger, 8, heat pump compressor, 9, radiator, 10, reversing valve, 11, proportional flow valve, 12, second water pump, 13, battery water cooling coil, 14, second expansion water kettle, 15, third water pump, 16, motor water cooling coil, 17, third expansion water kettle, 18, in-cabin heat exchanger, 19, reversing valve, 20, out-cabin heat exchanger. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0027] It is also important to note that the terms used herein are not intended to limit the particular embodiments of the present application which are described herein. Rather, these terms are used merely to describe specific embodiments of the present application. As used herein, unless otherwise indicated, the use of the singular includes the plural and back again; and, the use of "and / or" means "and" have "or" unless otherwise indicated. Furthermore, to the extent that any reference is made herein to method steps, such reference is intended to mean a combination of hardware and software implementing the described functionality that is present in one or both of the following: The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0028] Embodiment: The embodiment of the present application provides an integrated thermal management system of an electric vehicle based on a fused salt composite heat storage material, as shown in the figure, comprising a device thermal management module, a composite material heat exchange module, an air conditioning module and a control module. Figure 1 The device thermal management module is used for heat regulation of electric vehicle components.

[0029] The device thermal management module is used for heat regulation of electric vehicle components.

[0030] The electric vehicle components include motors, batteries and other electronic devices affected by heat regulation. Taking the motors and batteries as examples. The device thermal management module includes a motor thermal management module and a battery thermal management module. The motor thermal management module is used for heat exchange with the composite material heat exchange module through the flow of cooling liquid according to the temperature of the motor. The battery thermal management module is used for heat exchange with the composite material heat exchange module through the flow of cooling liquid according to the temperature of the battery.

[0031] The battery thermal management module includes a second water pump 12, a battery water cooling coil 13 and a second expansion water kettle 14 connected in series. The motor thermal management module includes a third water pump 15, a motor water cooling coil 16 and a third expansion water kettle 17 connected in series. The motor water cooling coil 16 is connected with the battery water cooling coil 13, and the second water pump 12 and the third water pump 15 are connected, thereby forming a loop.

[0032] The motor thermal management module and the battery thermal management module are connected in parallel, and the motor thermal management module and the battery thermal management module are connected in parallel with the fused salt composite material heat exchanger 7.

[0033] When the ambient temperature is within the normal operating temperature range of 0-30℃, the battery thermal management module starts to operate, and temperature monitoring and normal temperature thermal management are performed. When the battery temperature rises and exceeds the set upper limit threshold of the battery temperature, the cooling liquid in the battery water cooling coil increases in temperature, and the second water pump is started to pump out the high-temperature cooling liquid from the battery system while pumping in cooling liquid with a lower temperature to take away the heat generated inside the battery. The high-temperature cooling liquid pumped out enters the molten salt composite heat storage material heat exchanger to transfer and store heat in the molten salt composite heat storage material heat exchanger. When the battery temperature decreases and exceeds the set lower limit threshold of the battery temperature, the low-temperature cooling liquid enters the molten salt composite heat storage material heat exchanger, increases in temperature after absorbing the previously stored heat, and then the second water pump is used to pump out the cold water and pump in the hot water into the battery water cooling coil to achieve heating of the battery.

[0034] When the motor thermal management module operates, the system can automatically adjust the flow of the cooling liquid according to the real-time monitored temperature changes of the motor and the circuit module to dynamically regulate the heat, so as to ensure that the key components work within a reasonable temperature range, thereby ensuring the stability and long-term reliability of the whole vehicle system. When the temperature of the motor or the motor-related circuit rises and exceeds the upper limit threshold of the motor, the temperature of the cooling liquid in the motor water cooling coil increases, and the third water pump is started to pump out the high-temperature cooling liquid from the system while injecting low-temperature cooling liquid to timely take away the heat generated by the motor module. The high-temperature cooling liquid that flows out then enters the molten salt composite heat storage material heat exchanger to transfer and store heat in the molten salt composite heat storage material heat exchanger, thereby effectively cooling the motor and the circuit module. During operation, the third expansion water tank is used to buffer the volume fluctuation caused by the temperature change of the cooling liquid to maintain the stability and safety of the system. When the temperature of the motor or the motor-related circuit decreases and exceeds the lower limit threshold of the motor, the low-temperature cooling liquid enters the molten salt composite heat storage material heat exchanger, increases in temperature after absorbing the previously stored heat, and then the third water pump is used to pump out the cold water and pump in the hot water into the motor water cooling coil to achieve heating of the motor.

[0035] The composite material heat exchange module is used to adjust the flow direction and circulation mode of the cooling liquid according to the temperature change of the molten salt composite heat storage material.

[0036] The composite heat exchange module comprises a thermostat 2, a first water pump 3, a two-way valve 4, a first expansion water tank 5, a three-way valve 6, a molten salt composite heat storage material heat exchanger 7, a heat pump compressor 8, a radiator 9, a reversing valve 10 and a proportional flow valve 11. One end of the molten salt composite heat storage material heat exchanger 7 is connected to the proportional flow valve 11, the other end of the proportional flow valve 11 is connected to the reversing valve 10, the heat pump compressor 8, the outlet of the bypass valve of the thermostat 2 and the outlet of the radiator 9, the outlet of the main valve of the thermostat 2 is connected to the inlet of the radiator 9, the inlet of the main valve of the thermostat 2 is connected to the outlet of the first water pump 3, and the inlet of the radiator 9 is connected to the inlet of the molten salt composite heat storage material heat exchanger 7. The other end of the molten salt composite heat storage material heat exchanger 7 is connected to the three-way valve 6, the other end of the three-way valve 6 is connected to the outlet of the two-way valve 4 and the in-cabin heat exchanger 18, and the two-way valve 4 is connected to the inlet of the first water pump 3. The composite heat exchange module is designed in parallel with the heat pump compressor and the radiator and the like, so that it has more paths for heat dissipation or heat absorption, can more flexibly perform heat management, better improves heat regulation efficiency and quickly reaches a suitable temperature.

[0037] To ensure stable operation of the heat pump system, the system is provided with expansion water tanks, including a first expansion water tank 5, a second expansion water tank 14 and a third expansion water tank 17, for coping with volume expansion or contraction of the cooling liquid caused by temperature change under different working conditions. The expansion water tank can effectively prevent problems such as leakage, air blockage or overpressure caused by pressure fluctuation of the circuit, thereby ensuring safety and sealing of the heat pump system. In the circuit shared by the water pump and the expansion water tank, the water pump is arranged at the front end of the circuit to ensure sufficient liquid, direct flow through the water-cooled coil can improve heat exchange efficiency, and the expansion water tank is located at the end of the circuit to facilitate exhaust separation of the gas released by the heated or cooled liquid. In addition, the water-cooled coil is located in the middle of the circuit to facilitate bidirectional heat absorption or heat release.

[0038] The molten salt has high specific heat capacity and phase change latent heat, can absorb a large amount of heat when melting within a certain temperature range, and release heat when solidifying. When the temperature is too high, the cooling liquid conducts heat to the molten salt module, and the molten salt absorbs heat and melts; when the temperature is too low, the molten salt gradually solidifies and releases heat, releases phase change latent heat, and heats the cooling liquid. The process is reversible and can work continuously. Therefore, the composite material of the molten salt composite heat storage material heat exchanger 7 in the composite heat exchange module of the embodiment is nitrate molten salt composite heat storage material. Compared with other molten salt systems, the nitrate molten salt composite heat storage material has the advantages of "suitable phase change temperature, good thermal stability, low corrosion and high energy storage density" in electric vehicle thermal management, is a phase change heat storage scheme with mature technology, high safety and good engineering application prospect. At the same time, the molten salt composite heat storage material heat exchanger in the embodiment is constructed by combining metal foam and nitrate molten salt composite heat storage material, which improves the thermal conductivity and prevents molten salt leakage, and improves the stability of the structure.

[0039] The embodiment sets a metal foam block with a pore structure inside the heat exchanger, fills the molten nitrate salt composite heat storage material in the pores of the metal foam, and forms a "dense contact" composite after cooling. Because the metal foam has a very high specific surface area and thermal conductivity, it can achieve rapid heat transfer on a microscopic scale. At the same time, the metal foam provides support for the nitrate salt composite heat storage material, preventing the molten salt from migrating, depositing, and losing during the heating-cooling cycle. The phase change temperature of the nitrate salt composite heat storage material in the embodiment is about 135℃, the phase change latent heat can reach 210J / g, the liquid specific heat capacity is 1.5J / g·K, and the thermal conductivity after composite enhancement is about 1.0W / m·K, which has good thermal response capacity, high heat storage density and low corrosion.

[0040] The temperature change of the molten salt composite heat storage material is derived from the external heat input or output. When the electric vehicle is running or the external temperature is too high, the electric motor, battery and other components will generate a large amount of heat, which is taken away by the cooling liquid. When the cooling liquid flows through the molten salt composite heat storage material heat exchanger, the heat is transferred from the cooling liquid to the molten salt, and the molten salt starts to absorb heat and may undergo phase change melting. When the ambient temperature is too low, the molten salt composite material starts to release the heat stored before, and transfers the heat to the cooling liquid flowing through the heat exchanger. The molten salt solidifies from liquid to solid, and the material temperature decreases at the same time.

[0041] The specific working principle is as follows: When the composite material heat exchange module works, the system intelligently adjusts the flow direction and circulation mode of the cooling liquid according to the temperature change of the molten salt composite heat storage material, so as to realize effective heat energy management. When the temperature of the molten salt composite heat storage material rises and exceeds the set material temperature upper limit threshold, the cooling liquid flows through the molten salt composite heat storage material heat exchanger under the regulation of the proportional flow valve, and then converges again after completing the heat absorption and transfer. The first water pump starts to pump out the high-temperature cooling liquid, and at the same time, the cooling liquid with lower temperature is injected to enhance the cooling capacity of the system. The cooling liquid flows through the thermostat, and when the temperature decreases and is lower than the set temperature, the cooling liquid flows out of the bypass valve of the thermostat and directly flows back to the molten salt composite heat storage material heat exchanger through the proportional flow valve. When the temperature is higher than the set temperature, the cooling liquid flows out of the main valve of the thermostat, is cooled by the radiator, and then flows back to the molten salt composite heat storage material heat exchanger through the proportional flow valve, so as to realize the cooling of the system.

[0042] The air conditioning module is used for heating or cooling air or cooling liquid in a closed environment, so as to adjust the temperature in the passenger cabin, and is linked with the whole vehicle thermal management system.

[0043] The air conditioning module comprises an air conditioning fan 1, an in-cabin heat exchanger 18, a reversing valve 19 and an out-cabin heat exchanger 20, which are connected in series. The air conditioning fan adjusts the air volume to push the air flow, assists the air conditioning system to realize heat exchange, and improves the response speed and efficiency of thermal management. The air blown by the air conditioning fan passes through the in-cabin heat exchanger, and the air and the cooling liquid exchange heat through the wall surface of the heat exchanger.

[0044] When the system temperature is too high, the cooling liquid first flows through the molten salt composite heat storage material heat exchanger, but the module has reached the upper limit of heat storage, and cannot continue to absorb system heat, and the system enters a high-temperature overload state. At this time, the reversing valve is opened, the heat pump compressor is started and switched to refrigeration mode, and the heat pump compressor starts to work to compress the cooling liquid, so that it changes from a low-temperature low-pressure state to a high-temperature high-pressure gas state. The high-temperature cooling liquid flows to the molten salt composite heat storage material heat exchanger through the reversing valve and exchanges heat with the high-temperature cooling liquid in the molten salt composite heat storage material heat exchanger. The cooling liquid condenses after absorbing heat and changes to a low-temperature low-pressure liquid state. It enters the heat pump compressor again through the first water pump and enters the next cycle. At the same time, the cooling liquid in the molten salt composite heat storage material heat exchanger flows to the out-cabin heat exchanger through the three-way valve and releases heat to the ambient air. The cooling liquid condenses from a gas state to a liquid state, and the low-temperature low-pressure liquid cooling liquid then flows into the in-cabin heat exchanger. The cooling liquid cools down and flows back to the molten salt composite heat storage material heat exchanger, forming a complete cooling cycle. At this time, because the system temperature is too high, the temperature in the vehicle is too high, and the air conditioning fan blows the hot air in the vehicle through the surface of the molten salt composite heat storage material heat exchanger. The cooling liquid absorbs the heat in the air to reduce the temperature of the air in the vehicle and achieve the refrigeration effect. At the same time, the parallel radiator is opened synchronously to further enhance the cooling efficiency and accelerate the release of system waste heat. This process actively intervenes in the molten salt composite heat storage module when the heat exchange capacity is insufficient or the heat storage is saturated, effectively transfers the excess heat in the system to the external environment through the cooling liquid circulation, and prevents the performance of the battery, motor and other key components from being affected or generating a thermal runaway risk due to overheating.

[0045] When the system temperature is too low, the cooling liquid first flows through the molten salt composite heat storage material heat exchanger to obtain heat. However, if the module is in a low-temperature solid state, has not completed melting or the upper cycle heat storage capacity is exhausted, and cannot provide sufficient heat, the system will enter a low-temperature heating insufficient state. At this time, the reversing valve is opened, the heat pump compressor is started, and the heating mode is switched to. The heat pump compressor starts to work, compresses the refrigerant in the low-temperature and low-pressure state, and changes it into a high-temperature and high-pressure gas state. The high-temperature gaseous refrigerant flows to the molten salt composite heat storage material heat exchanger through the reversing valve, and exchanges heat with the cooling liquid therein. The cooling liquid absorbs heat and warms up, and returns to the molten salt composite heat storage material heat exchanger through the first water pump. At the same time, the cooling liquid in the molten salt composite heat storage material heat exchanger can also flow to the external heat exchanger through the three-way valve, absorb heat from the environment and warm up, and the warmed-up cooling liquid continues to flow into the cabin heat exchanger to release the heat carried to the air in the passenger cabin, realize the air temperature rise and heating function in the cabin, and improve the thermal comfort of the passenger cabin. The cooled cooling liquid returns to the molten salt composite heat storage material heat exchanger to complete a closed heating cycle. The process actively provides heat by the heat pump system in the case that the molten salt module does not complete the heat release preparation or its heating capacity is insufficient, and efficiently transfers heat energy to the battery, electric drive system and passenger cabin through heat exchange with the cooling liquid, to ensure the normal start and operation of the whole vehicle in a low-temperature environment.

[0046] A control module is configured to construct an optimal control strategy based on a minimum principle, and control the equipment thermal management module, the air conditioning module and the composite material heat exchange module according to the optimal control strategy. The strategy introduces the battery temperature as a key state variable on the basis of a traditional energy management model to form a target optimization control framework of fuel consumption.

[0047] As shown in Figure 2 , the specific steps are as follows: The control system takes the power demand of the drive motor, the state of charge (SOC) of the battery, the battery temperature, the motor temperature, the ambient temperature and the cooling liquid temperature as input variables, establishes an optimization function with the minimum fuel consumption as the target, and adjusts the engine power, the motor power and the battery charging and discharging power in real time. The engine output power, the battery charging and discharging power and the motor load are dynamically adjusted to realize the collaborative optimal control of energy distribution and thermal state.

[0048] ECMS (equivalent fuel minimum consumption strategy) uses an equivalence factor to equalize the power consumption of the engine and the fuel consumption, adds the fuel consumption of the engine to obtain the equivalent fuel consumption, and then solves the optimization problem of the minimum equivalent fuel consumption rate to obtain the optimal control variable. The equivalent fuel consumption rate calculation formula is as follows: .

[0049] wherein, For equivalent fuel consumption rate; For engine instantaneous fuel consumption rate; For equivalent fuel consumption rate; s is the equivalent coefficient; For battery output power; For fuel low heat value.

[0050] But in the actual control process, with the change of working conditions, it is difficult to maintain the SOC at the target value by using a fixed equivalent coefficient, so it is necessary to dynamically adjust the equivalent coefficient. This embodiment considers that the range extended electric vehicle system is discrete, and uses a discrete PI controller based on SOC feedback to update the equivalent factor in real time. The adaptive equivalent factor It is composed of an initial equivalent factor and an adaptive term, which can be expressed as: .

[0051] Among them, is the initial equivalent factor, is the proportional coefficient, is the integral coefficient, is the system sampling time, is the target SOC, is the instantaneous SOC. Not only the initial value of the equivalent factor, but also the of the previous moment , the remaining two are SOC feedback adjustment terms based on PI controller, which prevent SOC from deviating too much from the target value. Indicates the time when a cycle starts, Indicates the time when a cycle ends.

[0052] The equivalent fuel consumption rate calculation formula is further expressed as: .

[0053] When the equivalent coefficient is small, the cost of using electric energy is low enough, the system tends to have small motor power output, and the power required for the mine truck to run is mainly provided by the battery; When the equivalent coefficient is large, the strategy tends to use the energy generated by the range extender, the system tends to have large motor power output, and the range extender will work at a large power working point to charge the battery. With the strategy running, the initial equivalent coefficient is constantly updated, and if the trip is long enough, the effect of the initial equivalent coefficient on A-ECMS can be ignored.

[0054] The control module of the embodiment includes various input variables, including driving motor power demand, battery SOC, battery temperature, motor temperature, ambient temperature, and coolant temperature. Through multi-physical field coupling modeling of the power system and the thermal management system, a dynamic correlation between the state of charge and the state of heat is established, providing a basis for subsequent energy management and thermal management collaborative control. The system optimization control module is based on the principle of minimum equivalent fuel consumption, designs a multivariable optimization function containing an equivalent factor self-adjusting mechanism, and introduces a dual constraint adjustment mechanism for battery SOC and temperature in the control solving process, achieving adaptive collaborative control of energy distribution and thermal management. Compared with existing methods, the embodiment not only establishes a thermal-electric collaborative relationship through a physical model, but also further introduces a state feedback adjustment mechanism, so that the engine power, motor power, and battery charging and discharging power can achieve the minimum fuel consumption target while ensuring the thermal safety and electrical sustainability of the system, with good dynamic response capability and working condition adaptability.

[0055] When the battery temperature exceeds the set threshold, the control strategy automatically limits the battery discharge power and preferentially uses the engine to supply power, while starting the first water pump and the low-temperature molten salt composite heat storage material heat exchanger for heat dissipation. When the battery temperature is too low and exceeds the set threshold, moderate charging is allowed to raise the temperature, and if necessary, the heat pump air conditioning system is started to assist in heating the battery, ensuring that the battery is always within the efficient and safe operating temperature range.

[0056] During system operation, the control module determines the thermal and electrical energy requirements in real time according to the vehicle operating conditions and battery state, automatically switches to the corresponding mode, adjusts the coolant flow direction and flow rate, and achieves rapid response and global regulation. The embodiment incorporates battery temperature into the energy control system, achieving thermal-energy collaborative management, which not only effectively addresses multi-source thermal loads and variable operating conditions, but also helps extend battery life and improve the development level of the vehicle system in the direction of green and intelligent. The use of a heat pump system can assist in cooling or heating the thermal management system under high temperature or extremely cold conditions, achieving improved thermal efficiency and energy efficiency of the vehicle.

[0057] Through the above control method, the system improves the engine fuel economy, extends the battery life, and enhances the running stability and environmental adaptability of the vehicle system under complex operating conditions such as fast charging, high load, and extreme weather, while ensuring the power output of the vehicle.

[0058] Those skilled in the art can clearly understand the technical solutions of the present application from the above description of the embodiments of the present application without any creative work, and therefore the above description is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical scope disclosed by the present application, and all these changes or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0059] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical scope disclosed by the present application, and all these changes or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An integrated thermal management system for electric vehicles based on molten salt composite heat storage materials, characterized in that: include: Equipment thermal management module, used to regulate the heat of electric vehicle components; Composite material heat exchange module, used to adjust the flow direction and circulation mode of the coolant according to the temperature change of the molten salt composite heat storage material; Air conditioning modules, used to heat or cool air or coolant in a closed environment; The control module is used to construct an optimal control strategy based on the minimum principle, and control the equipment thermal management module, air conditioning module and composite material heat exchange module according to the optimal control strategy.

2. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 1, characterized in that: The equipment thermal management module includes a motor thermal management module and a battery thermal management module. The motor thermal management module is used to exchange heat with the composite material heat exchange module through the flow of coolant according to the temperature of the motor. The battery thermal management module is used to exchange heat with the composite material heat exchange module through the flow of coolant according to the temperature of the battery.

3. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 2, characterized in that: The battery thermal management module includes a second water pump, a battery water cooling coil and a second expansion water pot connected in series, and the motor thermal management module includes a third water pump, a motor water cooling coil and a third expansion water pot connected in series.

4. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 3, characterized in that: The motor water cooling coil is connected to the battery water cooling coil, and the second water pump is connected to the third water pump.

5. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 4, characterized in that: The composite material heat exchange module includes a thermostat, a first water pump, a first expansion kettle, a molten salt composite heat storage material heat exchanger, a heat pump compressor, a radiator, a reversing valve and a proportional flow valve, wherein one end of the molten salt composite heat storage material heat exchanger is connected to the proportional flow valve, the other end of the proportional flow valve is connected to the outlet of the reversing valve, the heat pump compressor, the thermostat bypass valve and the radiator outlet, the thermostat main valve outlet is connected to the radiator inlet, the thermostat main valve inlet is connected to the outlet of the first water pump, and the radiator inlet is connected to the inlet of the molten salt composite heat storage material heat exchanger.

6. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 5, characterized in that: The composite heat exchange module also includes a three-way valve and a two-way valve. The other end of the molten salt composite heat storage material heat exchanger is connected to the three-way valve, the other end of the three-way valve is connected to the outlet of the two-way valve and the cabin heat exchanger, and the two-way valve is connected to the inlet of the first water pump.

7. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 1, characterized in that: The air conditioning module includes an air conditioning fan, an in-cabin heat exchanger, a reversing valve and an out-cabin heat exchanger, and the in-cabin heat exchanger, the reversing valve and the out-cabin heat exchanger are connected in series in sequence.

8. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 6, characterized in that: The motor thermal management module and the battery thermal management module are connected in parallel, and the motor thermal management module and the battery thermal management module are connected in parallel and in series with the molten salt composite material heat exchanger respectively.

9. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 1, characterized in that: The composite material in the composite heat exchange module is a nitrate molten salt composite heat storage material.

10. The integrated thermal management system for electric vehicles based on molten salt composite heat storage materials according to claim 1, characterized in that: In the control module, the specific steps of constructing the optimal control strategy based on the minimum principle are: Taking the drive motor power demand, battery state of charge, battery temperature, motor temperature, ambient temperature and coolant temperature as input variables, an optimization function with the goal of minimizing fuel consumption is established. The engine power, motor power and battery charge and discharge power are adjusted in real time, and the engine output power, battery charge and discharge power and motor load are dynamically adjusted to achieve coordinated optimal control of energy distribution and thermal state.

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