A secondary cycle thermal management system based on environmentally friendly refrigerant and control method

Abstract

The application discloses a kind of based on environmental protection refrigerant's secondary circulation heat management system and control method, including primary side indirect heat pump circulation module, first working medium of filling low global warming potential, concentrated arrangement in vehicle closed space, secondary side is pump-driven two-phase flow heat management circuit, filling low-pressure environmental protection insulation type second working medium includes liquid storage device, circulating pump, heat source heat exchange unit, outboard heat exchanger, heat exchanger, gas-liquid separation device, back pressure regulating device, check valve and multiple flow path switching valve, secondary side is divided into low temperature zone and high temperature zone according to heat management object operating temperature, low temperature zone includes passenger cabin and power battery heat management unit, high temperature zone uses multiple heat source cascade cooling structure, two heat management units can be switched in series by flow path switching valve, gas-liquid separation device is set between adjacent heat sources, the quality flow of working medium is reduced in the application, pipeline diameter can be correspondingly reduced, it is conducive to the compactification and light weight of heat management system.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for new energy vehicles, specifically to a secondary cycle thermal management system and control method based on environmentally friendly refrigerants. Background Technology

[0002] With increasingly stringent global requirements for greenhouse gas emissions, the trend of developing thermal management systems for new energy vehicles towards refrigerants with low global warming potential is becoming increasingly clear. Against this backdrop, natural compounds such as R744 and R290 are emerging as potential alternative refrigerants for thermal systems in new energy vehicles. R744, being non-flammable, can be used in direct, indirect, or hybrid thermal management architectures. However, R290 has high flammability. To reduce its charge volume and leakage risks, existing solutions often confine R290 to a relatively centralized, closed heat pump cycle module, employing an indirect thermal management system architecture that interacts with the secondary circuit via a plate heat exchanger.

[0003] Existing indirect thermal management systems often use antifreeze, i.e., a water-ethylene glycol mixture, as the heat transfer medium in the secondary circuit. They primarily rely on the sensible heat of the coolant to transfer heat to components such as the power battery, drive motor, and motor controller. As electric drive systems for new energy vehicles increasingly focus on higher power densities, traditional single-phase liquid cooling circuits are facing limitations in heat dissipation capacity, circulating pump power consumption, and pipeline pressure drop. Simultaneously, heat source components such as the power battery, drive motor, and motor controller have different optimal operating temperature ranges and heat generation characteristics, and the heat load of each heat source varies significantly with operating conditions such as acceleration, climbing, cruising, braking, and fast charging. However, existing single-phase liquid cooling circuits often use fixed series or parallel connections between heat sources, or rely on multi-way valves for limited flow path switching, making it difficult to simultaneously meet the demands for differentiated temperature control of heat sources in different temperature zones, enhanced heat dissipation for high heat flux density components, and cascaded utilization of coolant heat.

[0004] Therefore, in order to promote the application of indirect thermal management systems based on environmentally friendly working fluids such as R290 in new energy vehicles and to meet the heat dissipation requirements brought about by the continuous increase in power density of components such as power batteries, drive motors and motor controllers, it is necessary to upgrade and transform the traditional secondary side single-phase liquid cooling circuit. The traditional water-ethylene glycol single-phase sensible heat transfer method should be replaced with a pump-driven two-phase flow circulation using a low-pressure environmentally friendly working fluid. This can further utilize the latent heat of phase change of the cooling working fluid, improve the heat transport capacity of the secondary side, and provide a foundation for multi-temperature zone, tiered heat dissipation and multi-mode thermal management. Summary of the Invention

[0005] The purpose of this invention is to provide a secondary cycle thermal management system and control method based on environmentally friendly refrigerants to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A secondary cycle thermal management system based on environmentally friendly refrigerants, comprising: A primary-side indirect heat pump cycle module is filled with a first working fluid, which is an environmentally friendly working fluid with low global warming potential. The primary-side indirect heat pump cycle module is centrally arranged in the enclosed space of the vehicle and interacts with the secondary side through at least two primary refrigerant-secondary cooling working fluid heat exchangers. A secondary-side pump-driven two-phase flow heat management circuit is provided, wherein the secondary-side pump-driven two-phase flow heat management circuit is charged with a second working fluid, the second working fluid being a low-pressure, environmentally friendly, and insulating two-phase cooling working fluid; the secondary-side pump-driven two-phase flow heat management circuit includes a liquid storage device, a circulating pump, a heat source heat exchange unit, an external heat exchanger, a primary refrigerant-secondary cooling working fluid heat exchanger, a gas-liquid separator, a gas phase back pressure regulating device, a one-way valve, and multiple flow path switching valves; The secondary side pump-driven two-phase flow thermal management circuit is divided into a low-temperature zone circuit and a high-temperature zone circuit according to the suitable operating temperature of the thermal management object; the low-temperature zone circuit includes a crew compartment thermal management unit and a power battery thermal management unit; the high-temperature zone circuit includes a drive motor thermal management unit and a motor controller power electronics thermal management unit. The high-temperature zone circuit adopts a multi-heat source cascade cooling structure. The drive motor thermal management unit and the motor controller power electronic thermal management unit are connected in series in a switchable manner through a flow path switching valve. The two can be selectively located in the upstream or downstream position according to different operating conditions. A gas-liquid separation device is installed between the adjacent upstream heat source and downstream heat source in the high-temperature zone circuit. The gas phase outlet of the gas-liquid separation device is connected to the gas phase bypass pipeline, and the liquid phase outlet of the gas-liquid separation device is connected to the inlet of the downstream heat source.

[0007] Preferably, the first working fluid is R290; The second working fluid is selected from any one of R1233zd(E), R1336mzz(Z), and R1224yd(Z).

[0008] Preferably, the low-temperature zone circuit and the high-temperature zone circuit are each independently equipped with a bladder-type liquid reservoir for independently adjusting the operating pressure of each temperature zone; In the low-temperature zone circuit, the crew compartment thermal management unit and the power battery thermal management unit are connected in parallel through a flow path switching valve, and each is equipped with an independent back pressure valve to independently adjust the evaporation pressure of its internal working fluid.

[0009] Preferably, a liquid protection unit is provided between the liquid phase outlet of the gas-liquid separation device and the downstream heat source. The liquid protection unit is used to increase the pressure of the liquid working fluid so that it is kept in a set subcooled or low dryness state before entering the downstream heat source. The liquid protection unit includes any one or a combination of an interstage booster pump, a subcooling heat exchanger, and a pressure-stabilizing liquid storage chamber.

[0010] Preferably, the gas phase outlet of the gas-liquid separation device is provided with a back pressure valve and a one-way valve. The back pressure valve is used to regulate the evaporation pressure and stabilize the separation pressure, and the one-way valve is used to prevent gas phase backflow.

[0011] Preferably, the series connection order of the drive motor thermal management unit and the motor controller power electronics thermal management unit in the high-temperature zone circuit is based on the heat source cooling priority. J i Sure; The heat source cooling priority J i The calculation formula is:

[0012] In the formula, J i For the first i Cooling priority of each heat source; For the first i Real-time heat production power of each heat source; For the first i The maximum heat output of each heat source; T i For the first i The current temperature of the heat source; T i,tar For the first i The target temperature of each heat source; T i,max For the first i The maximum permissible temperature of a heat source; d T i / d t For the first i Real-time temperature rise rate of a heat source; W Q , W T and W R These are the weighting coefficients for the corresponding evaluation indicators; J i The heat source with a larger value is located upstream of the cascade cooling circuit. J i The heat source with a smaller value is located downstream.

[0013] A control method for a secondary cycle thermal management system based on environmentally friendly refrigerants, the control method including the following operating modes: Summer high-temperature cooling mode: In the low-temperature zone circuit, the second working fluid is distributed to the crew cabin cooling air core and / or the power battery thermal management unit after being driven by the low-temperature zone circulation pump. After absorbing heat, the two-phase working fluid enters the evaporator-side heat exchanger of the primary side indirect heat pump circulation module to transfer heat to the first working fluid. In the high-temperature zone circuit, the second working fluid is driven by the high-temperature zone circulation pump and flows sequentially through the drive motor thermal management unit and the motor controller power electronic thermal management unit according to the heat source cooling priority. After absorbing heat, the two-phase working fluid directly enters the external condenser to discharge heat to the environment after gas-liquid separation. Spring and Autumn Natural Cooling Mode: The primary side indirect heat pump circulation module is shut down. In the low-temperature zone circuit, the second working fluid absorbs heat from the battery through the power battery thermal management unit and then directly enters the external condenser to release heat to the environment and condense. In the high-temperature zone circuit, the second working fluid flows through the drive motor thermal management unit and the motor controller power electronic thermal management unit in sequence according to the heat source cooling priority and then directly enters the external condenser to release heat to the environment. Winter heating mode: The primary side indirect heat pump circulation module is turned on. The second working fluid releases heat to the passenger compartment in the warm air core and then enters the condenser-side heat exchanger of the primary side indirect heat pump circulation module to absorb the condensation heat of the first working fluid. The evaporator-side heat exchanger of the primary side indirect heat pump circulation module selectively absorbs heat from one or more combinations of air source, power battery waste heat source, drive motor waste heat source and motor controller waste heat source. Summer battery fast charging mode: The primary side indirect heat pump circulation module is turned on. The second working fluid absorbs the heat of the battery fast charging through the power battery thermal management unit and then enters the evaporator heat exchanger of the primary side indirect heat pump circulation module. The heat is transferred to the external heat dissipation circuit through the primary side circulation and discharged to the environment. When there is a cooling demand in the passenger cabin at the same time, the second working fluid is diverted to the passenger cabin cold air core. Winter battery fast charging mode: When there is no heating demand in the passenger compartment, the primary side indirect heat pump circulation module shuts down, and the secondary working fluid absorbs the heat from the battery fast charging through the power battery thermal management unit and then directly enters the external condenser to release heat to the environment; when there is a heating demand in the passenger compartment, the primary side indirect heat pump circulation module turns on, and the secondary working fluid absorbs the heat from the battery fast charging through the power battery thermal management unit and then enters the evaporator-side heat exchanger of the primary side indirect heat pump circulation module, transferring the heat through the primary side circulation to the heater core for passenger compartment heating; when the residual heat from battery fast charging exceeds the passenger compartment heating demand, part of the secondary working fluid is diverted to the external condenser to release the excess heat to the environment; when the residual heat from battery fast charging is insufficient to meet the heating demand, the air source supplementary heating branch is activated.

[0014] Preferably, in the winter heating mode, when multiple heat source combination heating is selected, the second working fluid of each heat source branch is combined before entering the evaporator heat exchanger of the primary side indirect heat pump cycle module, so as to realize the synergistic utilization of heat from multiple heat sources. In the summer high-temperature cooling mode, the working fluid evaporation pressure of the crew cabin cooling air core and the power battery thermal management unit in the low-temperature zone circuit is independently adjusted by the back pressure valves installed on their respective branches.

[0015] Preferably, in the summer battery fast charging mode, when the passenger compartment has a cooling demand at the same time, the distribution ratio of the second working fluid to the power battery thermal management unit and the passenger compartment cooling core is determined according to the power battery temperature, the passenger compartment target temperature and the real-time heat load of both, and the power battery temperature is given priority to ensure that it does not exceed the set upper limit. In the winter battery fast charging mode, when there is a heating demand in the passenger compartment and the residual heat from the battery fast charging exceeds the heating demand, the diversion ratio of the second working fluid to the evaporator-side heat exchanger and the external condenser of the primary side indirect heat pump circulation module is dynamically adjusted according to the heating load of the passenger compartment and the real-time heat generation of the power battery.

[0016] Preferably, in the high-temperature zone circuit, after the gas-liquid two-phase working fluid from the upstream heat source outlet enters the gas-liquid separation device, the gas phase working fluid is transported to the external condenser for condensation via the gas phase bypass pipeline, and the liquid phase working fluid is pressurized by the liquid protection unit and then transported to the downstream heat source. The series connection order of the drive motor thermal management unit and the motor controller power electronics thermal management unit in the high-temperature zone circuit is based on the heat source cooling priority. J i Real-time dynamic switching, when the motor controller's J i The value is greater than that of the drive motor. J i When the value is active, the power electronics thermal management unit of the motor controller is located upstream; When the drive motor J i The value is greater than that of the motor controller. J i When the value is reached, the thermal management unit of the drive motor is located upstream.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention upgrades the secondary side from a traditional water or water-glycol single-phase liquid cooling circuit to a pump-driven two-phase flow thermal management circuit. The cooling medium absorbs heat simultaneously through sensible heat and latent heat of phase change as it flows through the heat source heat exchange unit. The latent heat of phase change of the two-phase working medium is much higher than the sensible heat of the single-phase liquid, significantly increasing the heat absorption capacity per unit mass of working medium. This results in a significant reduction in circulation flow rate, circulation pump power consumption, and pipeline flow losses under the same heat dissipation requirements. Simultaneously, due to the reduced working medium mass flow rate, the pipeline diameter can be correspondingly reduced, facilitating the compactness and lightweighting of the thermal management system.

[0018] 2. This invention divides the passenger compartment and power battery into a low-temperature zone and the drive motor and motor controller into a high-temperature zone. Each zone has an independent bladder-type liquid reservoir to independently regulate its operating pressure. In the low-temperature zone, the passenger compartment cooling air core and the power battery thermal management unit are each equipped with an independent back pressure valve, enabling independent adjustment of the working fluid evaporation pressure in each branch, thereby meeting the different target temperature requirements of the passenger compartment and the power battery. Similarly, the high-temperature zone circuit can independently adjust its operating parameters to meet the relatively high allowable operating temperature range of the motor and electronic control unit. Through this dual-temperature zone architecture, zoned management of heat sources at different temperature levels is achieved, avoiding the problem of mutual constraints between heat sources in different temperature zones within a single circuit.

[0019] 3. This invention employs a multi-heat-source tiered cooling structure in the high-temperature zone circuit, placing heat sources with higher cooling demands upstream to prioritize access to liquid working fluids with higher mass flow rates and lower dryness. A gas-liquid separation device is installed between adjacent upstream and downstream heat sources. The gaseous working fluid generated at the upstream heat source outlet is directly guided to the external condenser via a bypass branch, while the separated liquid working fluid continues to supply the downstream heat source. This structure ensures that the gaseous working fluid, having completed evaporation and heat absorption, promptly exits the main liquid supply path, avoiding problems such as increased two-phase pressure drop, decreased heat transfer coefficient, and insufficient effective liquid supply caused by high-gas-content two-phase flow entering the downstream heat source. The liquid mass flow rate decreases progressively along the heat source flow direction, achieving tiered utilization of the latent heat of phase change in the cooling working fluid and improving the overall cooling efficiency per unit mass of working fluid.

[0020] 4. This invention breaks through the limitations of traditional fixed series or fixed parallel connections, and proposes a method based on heat source cooling priority. J i The dynamic reconstruction mechanism. J i The evaluation index takes into account three dimensions: real-time heat generation power of the heat source, margin between the current temperature and the maximum allowable temperature, and temperature rise rate. J iHeat sources with larger values ​​indicate more urgent cooling needs and are prioritized for placement upstream in the cascade cooling loop. This dynamic reconfiguration mechanism enables the system to adaptively adjust the allocation of cooling resources based on the real-time thermal state of the motor and electronic control unit under different operating conditions (such as acceleration, climbing, cruising, braking, etc.), achieving on-demand supply of cooling capacity.

[0021] 5. This invention incorporates a liquid state protection unit between the liquid phase outlet of the gas-liquid separator and the downstream heat source. An interstage booster pump increases the pressure of the liquid working fluid, maintaining it at a predetermined subcooling or low dryness level before it enters the downstream heat source. This structure effectively prevents near-saturated liquid from flashing at the downstream heat source inlet due to pressure loss in the interstage piping, ensuring that the downstream heat source always receives a liquid or low-dryness working fluid and guaranteeing the reliable operation of the cascade cooling structure.

[0022] 6. This invention, through the coupling of a primary-side indirect heat pump and a secondary-side pump-driven two-phase flow, recovers waste heat generated during the operation of the power battery, drive motor, and motor controller as a heat source on the low-temperature side of the heat pump in winter heating mode, thereby improving the heat pump evaporation temperature and system COP. In summer cooling mode, the zoned management of the low-temperature and high-temperature zones eliminates the need for active cooling of the high-temperature electric drive system by the heat pump, reducing the compressor's cooling load. In spring and autumn when the ambient temperature is suitable, the compressor shuts down, relying entirely on natural ambient cooling, further reducing system energy consumption. These multi-level energy efficiency optimization measures significantly reduce the overall energy consumption of the vehicle's thermal management system. Attached Figure Description

[0023] Figure 1 This is a diagram of the architecture of the dual-working-fluid, dual-temperature-zone cascade thermal management system of the present invention. Figure 2 This is a diagram illustrating the working mode of the summer high-temperature thermal management system of the present invention. Figure 3 This is a diagram illustrating the working mode of the thermal management system for normal temperature conditions in spring and autumn according to the present invention. Figure 4 This is a diagram of the working mode of the winter low-temperature thermal management system of the present invention (air source heat extraction). Figure 5 This is a diagram of the working mode of the thermal management system for low-temperature winter conditions of the present invention (heat extraction from battery source). Figure 6 This is a diagram illustrating the working mode of the winter low-temperature thermal management system of the present invention (heat extraction via electric drive). Figure 7 This is a diagram illustrating the working mode of the thermal management system for fast charging of batteries in summer (no occupants in the passenger compartment) of the present invention. Figure 8 This is a diagram illustrating the working mode of the thermal management system for fast charging of batteries in summer (with occupants in the passenger compartment) of the present invention. Figure 9This is a diagram illustrating the working mode of the thermal management system for fast charging of batteries in winter (no occupants in the passenger compartment) of the present invention. Figure 10 This is a diagram of the working mode of the thermal management system for fast charging of batteries in winter (the passenger compartment has passengers, and the air source and battery source work together to extract heat). Figure 11 This is a diagram of the working mode of the thermal management system for fast charging of batteries in winter (occupant compartment has occupants, and the battery source extracts heat). Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Please see Figures 1-11 The present invention provides a technical solution: A secondary cycle thermal management system based on environmentally friendly refrigerants, comprising: The primary-side indirect heat pump cycle module preferably uses R290 as the first working fluid and is centrally located in a relatively enclosed and independent vehicle space to reduce the distribution of combustible working fluid throughout the vehicle. The primary-side refrigerant flows sequentially through the compressor, the primary-side refrigerant-secondary-side working fluid first heat exchanger, the expansion valve, the primary-side refrigerant-secondary-side working fluid second heat exchanger, and the dryer, forming a vapor compression cycle. The first heat exchanger acts as a condenser on the primary side, and the second heat exchanger acts as an evaporator on the primary side. Except for the primary-side vapor compression cycle, all other thermal management loops belong to the secondary-side pump-driven two-phase flow system. The secondary side preferably uses a low-pressure, low-GWP two-phase working fluid with electrical insulation properties, such as R1233zd(E), as the second working fluid, and is divided into a low-temperature zone, a high-temperature zone, and an auxiliary heat exchange loop according to the suitable operating temperature of the thermally managed object. The system switches between multiple operating modes through a combination of flow path switching valves, based on the ambient temperature, the passenger compartment's thermal requirements, and the real-time thermal status of the power battery, motor, and electronic control system.

[0026] Before the system is put into operation, it is necessary to first clarify the rules for determining the series connection order of the drive motor thermal management unit and the motor controller power electronic thermal management unit in the high-temperature zone circuit. This invention proposes a method based on heat source cooling priority. J i The dynamic judgment mechanism J i The calculation formula is:

[0027] In the formula J i For the first i Cooling priority of the heat source, Qi is the first i The real-time heat production power of the heat source, Qi,max, is the first... i The maximum heat production power of the heat source, Ti is the th i The current temperature of the heat source, T i,tar For the first i The target temperature of the heat source T i,max For the first i The maximum allowable temperature of a heat source, d T i / d t For the first i The real-time temperature rise rate of a heat source W Q , W T and W R These are the weighting coefficients for the corresponding evaluation indicators. J i A heat source with a larger heat value indicates a more urgent cooling demand and should be located upstream of the cascade cooling circuit to give it priority access to a liquid working fluid with a larger mass flow rate and lower dryness. J i The heat source with a smaller heat value is located downstream. This dynamic reconfiguration mechanism enables the system to adaptively adjust the allocation of cooling resources according to the real-time thermal state of the motor and electronic control under different operating conditions, thus achieving on-demand supply of cooling capacity.

[0028] Example 2: The difference between Example 2 and Example 1 is that: A method for using a secondary cycle thermal management system based on environmentally friendly refrigerants includes: In summer, the passenger compartment requires cooling due to high temperatures. The target operating temperature of the power battery is lower than the ambient temperature, while the drive motor and motor controller can operate at temperatures higher than the ambient temperature. Therefore, the system assigns the cooling air core and power battery thermal management unit to the low-temperature zone pump-driven two-phase flow cooling sub-circuit, and the drive motor thermal management unit and motor controller power electronics thermal management unit to the high-temperature zone pump-driven two-phase flow cooling sub-circuit. The operating pressures in the low-temperature and high-temperature zones are independently regulated by the first and second bladder-type liquid reservoirs, respectively.

[0029] In the cryogenic zone, the secondary working fluid stored in the first bladder-type reservoir is driven by the cryogenic zone gear pump and distributed to the cooling air core and the power battery thermal management unit by the first flow path switching valve according to the real-time cooling needs of the passenger compartment and the power battery. The first back pressure valve and the second back pressure valve are used to independently adjust the evaporation pressure of the working fluid in the cooling air core and the power battery thermal management unit, respectively, so as to meet the different target temperature requirements of the passenger compartment and the power battery. The working fluid absorbs heat and partially undergoes a phase change. The two-phase working fluid at the outlet enters the second heat exchanger through the second, third and fourth flow path switching valves, transferring the absorbed heat to the primary refrigerant evaporating in the second heat exchanger. After condensation or enthalpy reduction, the secondary working fluid returns to the cryogenic zone gear pump through the fifth, sixth and seventh flow path switching valves, completing the cryogenic zone cycle.

[0030] After absorbing heat from the low-temperature zone in the second heat exchanger, the primary-side refrigerant is compressed by the compressor and condenses and releases heat in the first heat exchanger. This heat is discharged to the environment through an independent external heat dissipation circuit. The secondary working fluid in the third bladder-type receiver is driven by the first gear pump and enters the first heat exchanger through the eighth, ninth, and tenth flow path switching valves to absorb the condensation heat of the primary-side refrigerant. Then, it enters the first external heat exchanger through the eleventh and twelfth flow path switching valves, where it releases heat to the environment under the action of the external fan. Finally, it returns to the first gear pump, completing the final heat dissipation to the environment. In the high-temperature zone, since the drive motor and motor controller can operate at temperatures higher than the ambient temperature, active cooling by the primary-side heat pump is not required. Its heat is preferentially discharged directly to the environment through the second external condenser.

[0031] In the high-temperature zone, because the drive motor and motor controller can operate at temperatures higher than the ambient temperature, active cooling by the primary-side heat pump is not required; the heat is preferentially discharged directly to the environment through the second external condenser. The working fluid in the high-temperature zone is driven by the second gear pump, and after passing through the thirteenth flow path switching valve, the cascade cooling sequence is determined based on the Ji values ​​of the drive motor and electronic control system. The motor controller... J iTaking a higher value as an example: The working fluid first enters the motor controller power electronic thermal management unit via the fourteenth flow path switching valve. The outlet two-phase working fluid enters the gas-liquid separation device via the fifteenth and sixteenth flow path switching valves. The separated gaseous working fluid directly enters the second external condenser via the third back pressure valve, one-way valve, seventeenth flow path switching valve, and eighteenth flow path switching valve. The separated liquid working fluid is pressurized by the interstage booster pump and then enters the drive motor thermal management unit via the nineteenth and twentieth flow path switching valves to continue absorbing heat. Subsequently, it enters the second external condenser via the twenty-first, twenty-second, eighteenth, and nineteenth flow path switching valves. After the two working fluids are condensed in the second external condenser, they return to the second gear pump via the twenty-third and twenty-fourth flow path switching valves, completing the staged cooling cycle. If the drive motor... J i If the value is higher, the upstream and downstream positions of the two are interchanged by a flow path switching valve, and the principle of interstage gas-liquid separation is the same.

[0032] Under normal temperature conditions in spring and autumn, the ambient temperature is usually sufficient to meet the direct heat dissipation requirements of the power battery, motor, and electronic control system. Therefore, the primary side indirect heat pump module is shut down, and the passenger compartment is ventilated by internal or external circulation via the cabin fan as needed. In the low-temperature zone, the secondary working fluid enters the power battery thermal management unit via the low-temperature zone gear pump and the first flow path switching valve. After absorbing heat from the battery, the two-phase working fluid sequentially enters the third external condenser via the second back pressure valve, the second flow path switching valve, the third flow path switching valve, and the twenty-fifth flow path switching valve, and directly releases heat to the environment for condensation. The condensed liquid working fluid returns to the low-temperature zone gear pump via the twenty-sixth flow path switching valve and the seventh flow path switching valve, completing the battery's natural cooling cycle. In the high-temperature zone, the flow path of the cooling working fluid in the pump-driven two-phase flow loop is consistent with that in the summer high-temperature conditions, and the upstream and downstream positional relationship of the electronic control system and motor is also based on the priority of the heat source. J i judge.

[0033] In low-temperature conditions during winter, the passenger compartment requires heating. When the primary side indirect heat pump module is activated, the system can select one or more of the following as low-temperature heat sources: ambient air, power battery, drive motor, and motor controller, to achieve coordinated heating from the air source and the vehicle's waste heat source.

[0034] On the crew compartment heating side, the secondary working fluid in the fourth bladder-type reservoir is driven by the heating loop gear pump and flows through the warm air core to release heat to the crew compartment. After cooling, the working fluid enters the first heat exchanger, absorbs the heat released by the condensation of the primary side refrigerant, and then returns to the heating loop gear pump through the eleventh flow path switching valve, thus forming the crew compartment heating cycle.

[0035] The heat source for the evaporation and heat absorption of the primary-side refrigerant in the second heat exchanger can be flexibly selected based on the available waste heat. In air source mode, the secondary working fluid is driven by the first gear pump and enters the second heat exchanger through the eighth, ninth, and fourth flow path switching valves, transferring heat to the primary-side refrigerant. It then enters the first external heat exchanger through the fifth and twelfth flow path switching valves, reabsorbing heat from the ambient air and returning to the first gear pump. In battery waste heat source mode, the secondary working fluid flows through the low-temperature zone gear pump, the first flow path switching valve, the power battery thermal management unit, the second back pressure valve, the second, third, and fourth flow path switching valves into the second heat exchanger, and then returns to the low-temperature zone gear pump through the fifth, sixth, and seventh flow path switching valves, utilizing the waste heat from the power battery operation as the low-temperature side heat source of the heat pump. In the electric drive waste heat source mode, taking the electric control as the upstream heat source as an example: the working fluid in the high-temperature zone flows sequentially through the second gear pump, the thirteenth flow path switching valve, the fourteenth flow path switching valve, the motor controller power electronic thermal management unit, the fifteenth flow path switching valve, and the sixteenth flow path switching valve before entering the gas-liquid separation device. The separated liquid phase enters the drive motor thermal management unit through the interstage booster pump, the nineteenth flow path switching valve, and the twentieth flow path switching valve. The separated gas phase merges with the working fluid at the drive motor outlet through the third back pressure valve and the check valve, and then enters the second heat exchanger through the nineteenth flow path switching valve, the twenty-seventh flow path switching valve, the twenty-eighth flow path switching valve, the ninth flow path switching valve, and the fourth flow path switching valve, transferring the electric drive waste heat to the primary side refrigerant. Then, it returns to the second gear pump through the fifth flow path switching valve, the sixth flow path switching valve, the twenty-third flow path switching valve, and the twenty-fourth flow path switching valve.

[0036] When multiple heat sources are selected for combined heating, the second working fluids of each heat source branch converge before entering the second heat exchanger, achieving synergistic utilization of heat from multiple heat sources. Therefore, the primary-side heat pump can dynamically select a single heat source or a combination of multiple heat sources based on the available heat from the air source, battery source, motor source, and electronic control source, improving the evaporator-side heat source temperature and waste heat utilization rate in low-temperature environments.

[0037] When the power battery is fast-charged in the high temperature environment of summer, the charging current and heat generation of the power battery increase significantly. Meanwhile, the vehicle drive motor and traction control are usually in a state of shutdown or low heat load. Therefore, this mode focuses on active cooling of the power battery in the low temperature zone. The second gear pump can be shut down or maintained at a low flow rate according to the actual thermal state of the electric drive system. The passenger compartment cooling circuit can be connected or isolated depending on whether there is a need for air conditioning when people are parked. When there is no need for cabin cooling, the first flow path switching valve preferentially or entirely introduces the cryogenic working fluid into the power battery thermal management unit. The secondary working fluid stored in the first bladder-type liquid reservoir is driven by the cryogenic gear pump and flows sequentially through the first flow path switching valve and the power battery thermal management unit. It absorbs the battery heat generated during fast charging through sensible heat absorption and latent heat of phase change. The two-phase working fluid at the battery outlet enters the second heat exchanger through the second back pressure valve, the second flow path switching valve, the third flow path switching valve, and the fourth flow path switching valve. In the second heat exchanger, it releases heat to the primary-side refrigerant, condenses, or reduces dryness. Then, it returns to the cryogenic gear pump through the fifth, sixth, and seventh flow path switching valves, completing the active cooling cycle of the battery cryogenic zone. The primary-side indirect heat pump module is activated simultaneously. The primary-side refrigerant evaporates in the second heat exchanger to absorb the heat from the fast charging of the power battery. After being compressed by the compressor, it enters the first heat exchanger for condensation, ultimately transferring the battery heat and the compressor input power to the external heat dissipation circuit. In the external heat dissipation circuit, the third bladder-type liquid reservoir is used for pressure stabilization and liquid storage. The secondary working fluid is driven by the first gear pump and enters the first heat exchanger through the eighth, ninth, and tenth flow path switching valves, absorbing the condensation heat of the primary-side refrigerant. Subsequently, it enters the first external heat exchanger through the eleventh and twelfth flow path switching valves, and the heat is discharged to the environment under the enhanced action of the external fan. The cooled working fluid returns to the first gear pump. When there is a cooling demand in the passenger compartment during fast charging in summer, the first flow path switching valve distributes the working fluid in the low-temperature zone to the power battery thermal management unit and the cold air core respectively according to the power battery temperature, the target temperature of the passenger compartment, and the real-time heat load of both. This allows the power battery fast charging cooling and the parking air conditioning cooling to share the primary-side heat pump module. The control system prioritizes ensuring that the power battery temperature does not exceed the set upper limit and meets the cooling demand of the passenger compartment within the remaining cooling capacity.

[0038] During rapid charging of the power battery in low-temperature winter environments, the drive motor and motor controller are typically shut down or under low heat load. The system primarily determines its operating mode based on the heat generated by the power battery's rapid charging and the passenger compartment's heating requirements. When there is no heating requirement in the passenger compartment, if the ambient temperature is sufficient for the direct heat dissipation of the power battery, the indirect heat pump module shuts down, prioritizing the use of the low-temperature environment as a natural cold source. The cooling medium in the low-temperature zone is driven by the low-temperature zone gear pump and enters the power battery thermal management unit through the first flow path switching valve. After absorbing the heat generated during the power battery's rapid charging, it passes through the second back pressure valve, the second flow path switching valve, the third flow path switching valve, and the twenty-fifth flow path switching valve to enter the third external condenser, where it exchanges heat with the ambient environment and condenses into a liquid phase. It then returns to the low-temperature zone gear pump through the twenty-sixth and seventh flow path switching valves, completing the direct cooling cycle of the power battery. When there is a heating requirement in the passenger compartment, the indirect heat pump module activates, prioritizing the use of the waste heat from the power battery's rapid charging as the heat source on the low-temperature side of the heat pump. The working fluid in the low-temperature zone enters the power battery thermal management unit via the low-temperature zone gear pump and the first flow path switching valve. After absorbing the heat from the battery's fast charging, it sequentially passes through the second back pressure valve, the second flow path switching valve, the third flow path switching valve, and the fourth flow path switching valve into the second heat exchanger. It transfers the waste heat from the power battery to the primary-side refrigerant evaporating in the second heat exchanger. Subsequently, it returns to the low-temperature zone gear pump via the fifth, sixth, and seventh flow path switching valves, forming a power battery waste heat recovery loop. The primary-side refrigerant, after absorbing the waste heat from the power battery, is compressed by the compressor and condenses and releases heat in the first heat exchanger. The working fluid in the secondary-side heating loop, driven by the heating loop gear pump, absorbs the heat released by the condensation of the primary-side refrigerant in the first heat exchanger and supplies heat to the passenger compartment through the passenger compartment heater core, thus forming a waste heat utilization path from the power battery's fast charging waste heat to the passenger compartment. When the waste heat from the fast-charging power battery is insufficient to meet the evaporator side requirements of the heat pump, the system activates the air source branch for supplemental heating. The secondary working fluid enters the second heat exchanger via the first gear pump, the eighth flow path switching valve, the ninth flow path switching valve, and the fourth flow path switching valve. It then flows into the first external heat exchanger via the fifth flow path switching valve and the twelfth flow path switching valve, absorbing heat from the outside air. This allows the waste heat source from the power battery and the air source to jointly serve as the low-temperature heat source for the indirect heat pump. When the waste heat from the fast-charging power battery exceeds the recoverable heat required for heating the passenger compartment, the working fluid at the battery outlet is diverted via the third flow path switching valve. A portion of this diverts through the fourth flow path switching valve into the second heat exchanger, providing a low-temperature heat source for heating the passenger compartment. The remaining portion enters the third external condenser via the twenty-fifth flow path switching valve, directly dissipating the excess battery heat to the environment. This achieves a dynamic distribution of the waste heat from the fast-charging power battery between passenger compartment heating and environmental heat dissipation.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A secondary cycle thermal management system based on environmentally friendly refrigerants, characterized in that, include: A primary-side indirect heat pump cycle module is filled with a first working fluid, which is an environmentally friendly working fluid with low global warming potential. The primary-side indirect heat pump cycle module is centrally arranged in the enclosed space of the vehicle and interacts with the secondary side through at least two primary refrigerant-secondary cooling working fluid heat exchangers. A secondary-side pump-driven two-phase flow thermal management circuit is provided, wherein the secondary-side pump-driven two-phase flow thermal management circuit is charged with a second working fluid, which is a low-pressure, environmentally friendly, and insulating two-phase cooling working fluid; the secondary-side pump-driven two-phase flow thermal management circuit includes a liquid storage device, a circulating pump, a heat source heat exchange unit, an external heat exchanger, a primary refrigerant-secondary cooling working fluid heat exchanger, a gas-liquid separation device, a gas phase back pressure regulating device, a one-way valve, and multiple flow path switching valves; The secondary side pump-driven two-phase flow thermal management circuit is divided into a low-temperature zone circuit and a high-temperature zone circuit according to the suitable operating temperature of the thermal management object; the low-temperature zone circuit includes a crew compartment thermal management unit and a power battery thermal management unit; the high-temperature zone circuit includes a drive motor thermal management unit and a motor controller power electronics thermal management unit. The high-temperature zone circuit adopts a multi-heat source cascade cooling structure. The drive motor thermal management unit and the motor controller power electronic thermal management unit are connected in series in a switchable manner through a flow path switching valve. The two can be selectively located in the upstream or downstream position according to different operating conditions. A gas-liquid separation device is installed between the adjacent upstream heat source and downstream heat source in the high-temperature zone circuit. The gas phase outlet of the gas-liquid separation device is connected to the gas phase bypass pipeline, and the liquid phase outlet of the gas-liquid separation device is connected to the inlet of the downstream heat source.

2. The secondary cycle thermal management system based on environmentally friendly refrigerant according to claim 1, characterized in that: The first working fluid is R290; The second working fluid is selected from any one of R1233zd(E), R1336mzz(Z), and R1224yd(Z).

3. The secondary cycle thermal management system based on environmentally friendly refrigerant according to claim 1, characterized in that: The low-temperature zone circuit and the high-temperature zone circuit are each independently equipped with a bladder-type liquid reservoir for independently adjusting the operating pressure of each temperature zone. In the low-temperature zone circuit, the crew compartment thermal management unit and the power battery thermal management unit are connected in parallel through a flow path switching valve, and each is equipped with an independent back pressure valve to independently adjust the evaporation pressure of its internal working fluid.

4. The secondary cycle thermal management system based on environmentally friendly refrigerant according to claim 1, characterized in that: A liquid protection unit is provided between the liquid phase outlet of the gas-liquid separation device and the downstream heat source. The liquid protection unit is used to increase the pressure of the liquid working fluid so that it is kept in a set subcooled or low dryness state before entering the downstream heat source. The liquid protection unit includes any one or a combination of an interstage booster pump, a subcooling heat exchanger, and a pressure-stabilizing liquid storage chamber.

5. The secondary cycle thermal management system based on environmentally friendly refrigerant according to claim 1, characterized in that: The gas-liquid separation device is equipped with a back pressure valve and a check valve at the gas phase outlet. The back pressure valve is used to adjust the evaporation pressure and stabilize the separation pressure, and the check valve is used to prevent gas phase backflow.

6. The secondary cycle thermal management system based on environmentally friendly refrigerant according to claim 3, characterized in that: The series connection order of the drive motor thermal management unit and the motor controller power electronics thermal management unit in the high-temperature zone circuit is based on the heat source cooling priority. J i Sure; The heat source cooling priority J i The calculation formula is: ； In the formula, J i The cooling priority for the i-th heat source; Let be the real-time heat production power of the i-th heat source; The maximum heat output power of the i-th heat source; T i T represents the current temperature of the i-th heat source. i,tar T represents the target temperature of the i-th heat source. i,max dT represents the maximum allowable temperature of the i-th heat source. i / dt represents the real-time temperature rise rate of the i-th heat source; W Q W T and W R These are the weighting coefficients for the corresponding evaluation indicators; J i A heat source with a larger value is positioned upstream of the cascade cooling circuit, J i The heat source with a smaller value is located downstream.

7. A control method for a secondary cycle thermal management system based on environmentally friendly refrigerants, characterized in that: The control method includes the following operating modes: Summer high-temperature cooling mode: In the low-temperature zone circuit, the second working fluid is distributed to the crew cabin cooling air core and / or the power battery thermal management unit after being driven by the low-temperature zone circulation pump. After absorbing heat, the two-phase working fluid enters the evaporator-side heat exchanger of the primary side indirect heat pump circulation module to transfer heat to the first working fluid. In the high-temperature zone circuit, the second working fluid is driven by the high-temperature zone circulation pump and flows sequentially through the drive motor thermal management unit and the motor controller power electronic thermal management unit according to the heat source cooling priority. After absorbing heat, the two-phase working fluid directly enters the external condenser to discharge heat to the environment after gas-liquid separation. Spring and Autumn Natural Cooling Mode: The primary side indirect heat pump circulation module is shut down. In the low-temperature zone circuit, the second working fluid absorbs heat from the battery through the power battery thermal management unit and then directly enters the external condenser to release heat to the environment and condense. In the high-temperature zone circuit, the second working fluid flows through the drive motor thermal management unit and the motor controller power electronic thermal management unit in sequence according to the heat source cooling priority and then directly enters the external condenser to release heat to the environment. Winter heating mode: The primary side indirect heat pump circulation module is turned on. The second working fluid releases heat to the passenger compartment in the warm air core and then enters the condenser-side heat exchanger of the primary side indirect heat pump circulation module to absorb the condensation heat of the first working fluid. The evaporator-side heat exchanger of the primary side indirect heat pump circulation module selectively absorbs heat from one or more combinations of air source, power battery waste heat source, drive motor waste heat source and motor controller waste heat source. Summer battery fast charging mode: The primary side indirect heat pump circulation module is turned on. The second working fluid absorbs the heat of the battery fast charging through the power battery thermal management unit and then enters the evaporator heat exchanger of the primary side indirect heat pump circulation module. The heat is transferred to the external heat dissipation circuit through the primary side circulation and discharged to the environment. When there is a cooling demand in the passenger cabin at the same time, the second working fluid is diverted to the passenger cabin cold air core. Winter battery fast charging mode: When there is no heating demand in the passenger compartment, the primary side indirect heat pump circulation module shuts down, and the secondary working fluid absorbs the heat from the battery fast charging through the power battery thermal management unit and then directly enters the external condenser to release heat to the environment; when there is a heating demand in the passenger compartment, the primary side indirect heat pump circulation module turns on, and the secondary working fluid absorbs the heat from the battery fast charging through the power battery thermal management unit and then enters the evaporator-side heat exchanger of the primary side indirect heat pump circulation module, transferring the heat through the primary side circulation to the heater core for passenger compartment heating; when the residual heat from battery fast charging exceeds the passenger compartment heating demand, part of the secondary working fluid is diverted to the external condenser to release the excess heat to the environment; when the residual heat from battery fast charging is insufficient to meet the heating demand, the air source supplementary heating branch is activated.

8. The control method for a secondary cycle thermal management system based on an environmentally friendly refrigerant according to claim 7, characterized in that: In the winter heating mode, when multiple heat sources are selected for combined heating, the second working fluids of each heat source branch converge before entering the evaporator heat exchanger of the primary side indirect heat pump cycle module, thereby achieving the synergistic utilization of heat from multiple heat sources. In the summer high-temperature cooling mode, the working fluid evaporation pressure of the crew cabin cooling air core and the power battery thermal management unit in the low-temperature zone circuit is independently adjusted by the back pressure valves installed on their respective branches.

9. The control method for a secondary cycle thermal management system based on an environmentally friendly refrigerant according to claim 8, characterized in that: In the summer battery fast charging mode, when the passenger compartment has a cooling demand at the same time, the distribution ratio of the second working fluid to the power battery thermal management unit and the passenger compartment cooling core is determined according to the power battery temperature, the passenger compartment target temperature and the real-time heat load of both, and the power battery temperature is given priority to ensure that it does not exceed the set upper limit. In the winter battery fast charging mode, when there is a heating demand in the passenger compartment and the residual heat from the battery fast charging exceeds the heating demand, the diversion ratio of the second working fluid to the evaporator-side heat exchanger and the external condenser of the primary side indirect heat pump circulation module is dynamically adjusted according to the heating load of the passenger compartment and the real-time heat generation of the power battery.

10. The control method for a secondary cycle thermal management system based on an environmentally friendly refrigerant according to claim 9, characterized in that: In the high-temperature zone circuit, after the gas-liquid two-phase working fluid from the upstream heat source outlet enters the gas-liquid separation device, the gas phase working fluid is transported to the external condenser for condensation via the gas phase bypass pipeline, and the liquid phase working fluid is pressurized by the liquid protection unit and then transported to the downstream heat source. The series connection order of the drive motor thermal management unit and the motor controller power electronics thermal management unit in the high-temperature zone circuit is based on the heat source cooling priority. J i Real-time dynamic switching, when the motor controller's J i The value is greater than that of the drive motor. J i When the value is active, the power electronics thermal management unit of the motor controller is located upstream; When the drive motor J i The value is greater than that of the motor controller. J i When the value is reached, the thermal management unit of the drive motor is located upstream.

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