A cooling system for power modules of new energy vehicles and its control method

Abstract

This invention discloses a cooling system and control method for a power module in a new energy vehicle, relating to the field of thermal management technology for new energy vehicles. The system includes an airbag reservoir, a pressure regulating device, a circulating pump, a power module radiator, a back pressure valve, a regenerator, an external condenser, a plate heat exchanger, and a flow path switching valve. The control method determines the target saturation temperature and target system saturation pressure based on the ambient temperature and adjusts the internal pressure of the airbag reservoir to ensure the heat exchange temperature difference on the condensing side. Based on the real-time heat load of the power module and the radiator outlet dryness threshold, the back pressure valve opening and pump flow rate are adjusted to actively regulate the radiator outlet pressure, thereby passively regulating the internal pressure drop of the radiator and the subcooling of the cooling medium inlet. The corresponding flow path is switched under low-loss summer, high-loss summer, and winter heat pump heat exchange conditions. This invention enables coordinated control of condensing capacity, radiator internal pressure drop, inlet subcooling, outlet dryness, and system energy consumption, improving the heat dissipation safety of the power module and the adaptability of the system under different operating conditions.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology for new energy vehicles, and in particular to a two-phase cooling system for the power module of a motor controller for a new energy vehicle and its control method. Background Technology

[0002] The power module of the motor controller in new energy vehicles is the core component for realizing power conversion and drive control between the power battery and the drive motor. Its thermal management performance directly affects the vehicle's power output, energy utilization efficiency, operational reliability, and service life. As electric drive systems develop towards higher power density, higher integration, and higher efficiency, the heat flux density generated by the power module under continuous high power output conditions increases significantly. If the heat dissipation capacity is insufficient, it can easily lead to increased chip junction temperature, localized temperature concentration, thermal aging of packaging materials, and increased device losses. Most existing power modules in new energy vehicles use single-phase liquid cooling for heat dissipation. However, single-phase liquid cooling mainly relies on the sensible heat of the coolant to absorb and remove heat. Under high heat flux density conditions, it is often necessary to increase the pump flow rate, increase the heat exchange area, or increase the fan speed. This can easily lead to problems such as increased additional energy consumption of the system, limited layout space, and insufficient heat dissipation margin. Therefore, it is difficult to fully meet the comprehensive requirements of the next generation of high-performance vehicle electric drive systems for the thermal safety and overall energy efficiency of the power module.

[0003] Two-phase cooling media can absorb a large amount of heat using the latent heat of phase change, and have the potential to improve the heat dissipation capacity of power modules. However, the operating scenarios of new energy vehicles are characterized by large ambient temperature variations, large fluctuations in the heat load of power modules, high fluctuation frequency, unstable heat exchange conditions on the condenser side, and complex overall thermal management requirements. If the two-phase cooling system only adopts a fixed pressure or single flow path operation mode, the condensation capacity may decrease in high-temperature environments due to insufficient heat exchange temperature difference between the saturation temperature of the cooling media and the ambient temperature. Under high heat load conditions, the condensation capacity may decrease due to insufficient subcooling at the inlet of the power module heat sink. Excessive dryness at the inlet and outlet can lead to localized evaporation and boiling crises. In winter, it is difficult to simultaneously meet the heat dissipation needs of the power module and the waste heat utilization needs of the heat pump system. Existing solutions typically treat system pressure regulation, back pressure regulation, and flow path switching as relatively independent control actions. They lack a unified and coordinated dual-layer pressure control and multi-condition collaborative operation strategy based on ambient temperature, power module heat load, inlet subcooling, outlet dryness, and system energy consumption. As a result, the stability, adaptability, and overall energy efficiency of the two-phase cooling system in new energy vehicle scenarios with wide temperature range, high load, and multiple operating conditions still need to be improved. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies, such as insufficient heat dissipation capacity of power modules in motor controllers for new energy vehicles, poor coordination between pressure regulation and flow path switching in two-phase cooling systems under different ambient temperatures and heat loads, and difficulty in simultaneously addressing condensation capacity, internal pressure drop of radiators, inlet subcooling, outlet dryness control, and system energy consumption. Therefore, this invention proposes a cooling system for power modules of new energy vehicles and its control method.

[0005] To address the problems existing in the prior art, the present invention adopts the following technical solution: A control method for a power module cooling system in a new energy vehicle includes: S1. Obtain the current ambient temperature, power module heat load, power module radiator inlet working fluid status, power module radiator outlet working fluid status, cooling fluid pump flow rate, and back pressure valve opening. S2. Determine the target saturation temperature of the cooling working fluid based on the current ambient temperature, and determine the target system saturation pressure based on the target saturation temperature; S3. The pressure regulation device of the airbag reservoir adjusts the internal pressure of the airbag reservoir so that the system operating pressure of the two-phase cooling circuit approaches the target system saturation pressure, so that the cooling working fluid forms a heat exchange temperature difference on the condensation side that meets the heat release requirements. S4. Determine the subcooling degree at the inlet of the power module radiator and the dryness degree at the outlet of the power module radiator based on the heat load of the power module, the working fluid state at the inlet of the power module radiator and the flow rate of the cooling working fluid pump. S5. Based on the comparison between the outlet dryness of the power module heat sink and the preset outlet dryness threshold, adjust the opening of the back pressure valve to actively regulate the outlet pressure of the power module heat sink, thereby regulating the inlet pressure, internal pressure drop and inlet subcooling of the power module heat sink. S6. Based on the current ambient temperature and power module heat load, switch between the low-loss flow path in summer, the high-loss flow path in summer, and the heat pump coupling flow path in winter through the flow path switching valve.

[0006] Preferably, determining the target saturation temperature of the cooling working fluid based on the current ambient temperature, and determining the target system saturation pressure based on the target saturation temperature, includes: Based on the current ambient temperature and the target heat exchange temperature difference on the condenser side, a target saturation temperature higher than the current ambient temperature is determined. Based on the correspondence between the saturation temperature and saturation pressure of the cooling medium, determine the target system saturation pressure corresponding to the target saturation temperature; The target heat exchange temperature difference on the condensing side is used to ensure that the cooling working fluid can release heat to the external environment and condense in the external condenser.

[0007] Preferably, the pressure regulating device for controlling the airbag reservoir adjusts the internal pressure of the airbag reservoir, including: When the system operating pressure of the two-phase cooling circuit is lower than the target system saturation pressure, the pressure regulating device of the airbag reservoir is controlled to increase the internal pressure of the airbag reservoir. When the system operating pressure of the two-phase cooling circuit is higher than the target system saturation pressure, the pressure regulation device of the airbag reservoir is controlled to reduce the internal pressure of the airbag reservoir. Specifically, the system operating pressure of the two-phase cooling circuit is changed by altering the internal pressure of the airbag reservoir, and the system saturation temperature of the cooling medium is changed simultaneously.

[0008] Preferably, determining the inlet subcooling of the power module heat sink and the outlet dryness of the power module heat sink includes: The inlet subcooling of the power module heat sink is determined based on the saturation temperature corresponding to the inlet working fluid temperature and inlet pressure conditions. The outlet dryness of the power module radiator is determined based on the power module heat load, the cooling medium pump flow rate, the power module radiator inlet subcooling, and the latent heat of vaporization of the cooling medium under the current saturation pressure. Among them, the inlet subcooling of the power module radiator is used to characterize the sensible heat absorption capacity of the cooling medium before it enters the saturated evaporation state, and the outlet dryness of the power module radiator is used to characterize the steam content state of the cooling medium when it flows out of the power module radiator.

[0009] Preferably, adjusting the back pressure valve opening based on a comparison between the power module radiator outlet dryness and a preset outlet dryness threshold includes: When the dryness of the power module heat sink outlet is not greater than the preset outlet dryness threshold, maintain the current back pressure valve opening, or reduce the downstream flow resistance of the power module heat sink under the condition of meeting the outlet dryness safety requirements. When the dryness of the power module heat sink outlet is greater than the preset outlet dryness threshold, the back pressure valve is controlled to adjust in the direction of increasing the downstream flow resistance of the power module heat sink, so as to increase the pressure of the working fluid at the outlet of the power module heat sink, and simultaneously increase the inlet pressure of the power module heat sink and increase the inlet subcooling of the power module heat sink. Furthermore, if the dryness of the power module radiator outlet is still greater than the preset outlet dryness threshold after adjustment by the back pressure valve, the pump flow rate of the circulating pump is increased to reduce the heat load borne by the unit mass of cooling working fluid, so that the dryness of the power module radiator outlet falls back to below the preset outlet dryness threshold.

[0010] Preferably, the low-loss flow path in summer includes: The cooling medium is pressurized by the circulating pump and enters the regenerator, where it exchanges heat with the high-temperature two-phase cooling medium from the outlet of the power module heat sink. The cooling medium, after heat exchange in the regenerator, enters the power module radiator to absorb heat from the power module. The high-temperature two-phase cooling medium flowing out of the power module heat sink enters the regenerator again after passing through the back pressure valve to release some heat, and then enters the external condenser for condensation. In the low-loss flow path during summer, the pressure regulation device of the airbag reservoir is used to maintain the heat exchange temperature difference on the condenser side, the back pressure valve is used to maintain the dryness of the power module radiator outlet within a safe range, and the regenerator is used to reduce the enthalpy of the cooling medium entering the external condenser.

[0011] Preferably, the high-loss flow path in summer includes: The cooling medium is pressurized by the circulating pump, bypasses the regenerator, and directly enters the power module heat sink; The two-phase cooling medium flowing out of the power module radiator enters the external condenser for condensation via the back pressure valve and the flow path switching valve in sequence. In the high-loss flow path during summer, the subcooling at the inlet of the power module radiator is increased by bypassing the regenerator, the pressure in the evaporation section of the power module radiator is increased by adjusting the back pressure valve, and the dryness at the outlet of the power module radiator is reduced by adjusting the pump flow rate of the circulating pump.

[0012] Preferably, the winter heat pump coupling flow path includes: The cooling medium is pressurized by the circulating pump and then enters the power module heat sink to absorb the heat from the power module. The two-phase cooling medium flowing out of the power module radiator enters the plate heat exchanger via a back pressure valve and a flow path switching valve. The two-phase cooling medium exchanges heat with the heat pump system in the plate heat exchanger to transfer the waste heat from the power module to the heat pump system. In the winter heat pump coupling flow path, the airbag liquid reservoir pressure regulation device is used to maintain the system saturation pressure of the two-phase cooling circuit, the back pressure valve is used to maintain the stability of the evaporative heat exchange state in the power module radiator, and the plate heat exchanger is used to assist the heat pump system in heating.

[0013] Preferably, the step of switching between a low-loss flow path in summer, a high-loss flow path in summer, and a heat pump coupling flow path in winter via a flow path switching valve based on the current ambient temperature and the heat load of the power module includes: When the current ambient temperature is higher than the preset ambient temperature threshold and the power module heat load is lower than the preset heat load threshold, switch to the summer low-loss flow path. When the current ambient temperature is higher than the preset ambient temperature threshold and the power module heat load is not lower than the preset heat load threshold, switch to the summer high loss flow path; When the current ambient temperature is not higher than the preset ambient temperature threshold and the heat pump system has a heating demand, switch to the winter heat pump coupling flow path. Each flow path switch synchronously updates the target saturation temperature, target system saturation pressure, back pressure valve opening, and pump flow rate.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a two-phase cooling system suitable for automotive motor controller power modules by setting up an airbag reservoir, an airbag reservoir pressure regulation device, an external condenser, a power module radiator, a back pressure valve, a regenerator, a plate heat exchanger, and a flow path switching valve. This allows the two-phase cooling medium to remove the heat generated by the power module through sensible heat absorption and latent heat absorption of phase change within the power module radiator. The airbag reservoir pressure regulation device actively adjusts the system saturation pressure and system saturation temperature of the two-phase cooling circuit according to the current ambient temperature, ensuring that the two-phase cooling medium maintains a heat exchange temperature difference that meets the heat release requirements on the external condenser side, thereby improving the problem of insufficient condensation capacity under high-temperature environments. At the same time, under low-loss conditions in summer, the high-temperature two-phase medium at the outlet of the power module radiator is pre-cooled by the regenerator before entering the external condenser, which can reduce the load on the external condenser and reduce the energy consumption of the external fan, improving the overall energy efficiency of the system while ensuring the heat dissipation requirements of the power module.

[0015] 2. This invention utilizes a back pressure valve located downstream of the power module radiator to adjust the radiator's inlet pressure and inlet subcooling based on the power module's heat load and the radiator's outlet dryness threshold. This allows the two-phase cooling medium entering the power module radiator to have a higher sensible heat absorption capacity and keeps the radiator's outlet dryness within a safe range, thereby reducing the risk of localized drying and boiling. In high-loss summer conditions, the system allows the subcooled liquid phase at the pump outlet to bypass the regenerator and directly enter the power module radiator, increasing the inlet subcooling and total heat absorption capacity. In winter heat pump heat exchange conditions, the system transfers waste heat from the power module to the heat pump system via a plate heat exchanger to assist in passenger compartment heating. Pressure regulation, back pressure adjustment, pump flow regulation, and multi-condition flow path switching form a coordinated control relationship, enabling the system to balance condensation capacity, inlet subcooling, outlet dryness control, and system energy consumption under different ambient temperatures and power module heat loads. This improves the wide-temperature-range adaptability, operational stability, and thermal safety of the vehicle motor controller's two-phase cooling system. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of a power module cooling system for a new energy vehicle according to an embodiment of the present invention; Figure 2This is a flowchart illustrating a control method for a power module cooling system of a new energy vehicle, provided as an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Example 1: This example provides a cooling system for the power module of a new energy vehicle. This system is used to cool the power module in the vehicle's motor controller. The power module of the vehicle's motor controller can be a SiC MOSFET power module, an IGBT power module, or other power semiconductor modules in the vehicle's electric drive system. This power module generates high heat loads during vehicle acceleration, hill climbing, high-speed cruising, frequent start-stop operations, and high-power output. If the heat cannot be dissipated in time, it can easily lead to increased chip junction temperature, aging of packaging materials, decreased electrical connection reliability, and reduced efficiency of the electric drive system. This example uses a two-phase cooling medium as the heat transfer medium. Through the absorption of sensible heat and latent heat of phase change within the power module's heat sink, efficient heat dissipation of the vehicle's motor controller power module is achieved.

[0019] like Figure 1 As shown, the two-phase cooling system of the vehicle motor controller includes an airbag reservoir, an airbag reservoir pressure regulating device, a filter, a circulating pump, a power module radiator, a regenerator, an external condenser, an external fan, a plate heat exchanger, a back pressure valve, a flow path switching valve, and a control unit. The flow path switching valve may include multiple three-way valves or an electronically controlled valve group capable of achieving equivalent flow path switching functions. The two-phase coolant is filled in the two-phase cooling circuit and stored in the airbag reservoir. The airbag reservoir is used to contain the coolant and buffer the volume change of the coolant during the phase change process. The airbag reservoir pressure regulating device is connected to the airbag reservoir and is used to regulate the gas pressure inside the airbag reservoir, thereby changing the system operating pressure of the two-phase cooling circuit and simultaneously changing the system saturation temperature of the two-phase coolant. A filter is installed at the inlet of the circulating pump to filter impurities in the two-phase coolant and reduce the adverse effects of bubbles, impurities, or localized flash evaporation on the pump inlet. The circulating pump drives the two-phase coolant to circulate within the two-phase cooling loop. The circulating pump can be a gear pump, a positive displacement pump, or other pump types suitable for low-pressure two-phase coolant circulation. The power module heatsink is thermally connected to the power module of the new energy vehicle motor controller, and the two-phase coolant absorbs heat generated by the power module within the heatsink. The power module heatsink can be a cold plate heatsink, a microchannel heatsink, a flow channel heatsink, or other heat exchange structures compatible with the power module's packaging structure. A back pressure valve is located downstream of the power module radiator to regulate the downstream flow resistance. Since the back pressure valve is located on the outlet side of the power module radiator, when it is adjusted in the direction of increasing flow resistance, both the outlet and inlet pressures of the power module radiator increase. Consequently, the saturation temperature of the two-phase cooling medium at the inlet of the power module radiator rises accordingly, increasing the subcooling of the inlet medium relative to this saturation temperature. In this way, the back pressure valve can regulate the evaporation section pressure, inlet subcooling, and outlet dryness within the power module radiator. The regenerator is installed between the outlet side of the circulating pump and the outlet side of the power module radiator. It facilitates heat exchange between the low-temperature liquid working fluid at the outlet of the circulating pump and the high-temperature two-phase working fluid at the outlet of the power module radiator under low-loss conditions in summer. Through the regenerator, the high-temperature two-phase working fluid at the outlet of the power module radiator releases some heat before entering the external condenser, reducing the enthalpy of the cooling working fluid entering the external condenser, thereby alleviating the heat load on the external condenser and reducing the power consumption of the external fan. An external condenser is used to condense the two-phase coolant by releasing heat to the outside environment, while an external fan enhances heat exchange between the external condenser and the outside air. A plate heat exchanger facilitates heat exchange between the two-phase coolant and the heat pump system, especially in winter conditions, transferring waste heat generated by the vehicle's motor controller power module to the heat pump system to assist in heating the passenger compartment. The heat pump system may include a compressor, an internal condenser, an expansion valve, an external evaporator, and corresponding heat pump-side flow path switching valves. The control unit is connected to the airbag reservoir pressure regulation device, circulating pump, back pressure valve, flow path switching valve, external fan, and relevant sensors. These sensors acquire at least the following parameters: current ambient temperature, two-phase cooling circuit system pressure, power module radiator inlet temperature, power module radiator outlet temperature, power module radiator inlet pressure, power module radiator outlet pressure, cooling fluid pump flow rate, back pressure valve opening, and heat pump system heating requirements. Based on these parameters, the control unit determines the target saturation temperature, target system saturation pressure, power module radiator inlet subcooling, power module radiator outlet dryness, target back pressure valve opening, target circulating pump flow rate, and flow path switching status.

[0020] In this embodiment, the airbag reservoir pressure regulation device is used to form system-level pressure regulation, the back pressure valve is used to form local pressure regulation in the evaporation section, and the flow path switching valve is used to form multi-condition operation path switching. These three devices do not operate independently, but rather work together under the unified control of the control unit to affect the condenser-side heat exchange temperature difference, the power module radiator inlet subcooling, the power module radiator outlet dryness, and the system energy consumption. This enables the two-phase cooling system of the new energy vehicle motor controller power module to operate stably under different ambient temperatures and different power module heat loads.

[0021] Example 2, as Figure 2 As shown, this embodiment provides a control method for a power module cooling system of a new energy vehicle. This method is applied to the two-phase cooling system of the power module of the new energy vehicle motor controller described in Embodiment 1. The core of this control method lies in adjusting the system saturation pressure and system saturation temperature of the two-phase cooling circuit according to the ambient temperature through the pressure regulating device of the airbag reservoir; adjusting the inlet and outlet pressures and inlet subcooling of the radiator according to the heat load of the power module and the dryness of the radiator outlet through the back pressure valve; and switching different working fluid flow paths according to the ambient temperature, the heat load of the power module, and the heating demand of the heat pump system through the flow path switching valve. This allows the pressure regulation and flow path switching to jointly serve the balance of condensation capacity, internal pressure drop of the radiator, inlet subcooling, outlet dryness, and system energy consumption. Specifically, the control unit first acquires the current ambient temperature, the thermal load of the power module of the new energy vehicle motor controller, the inlet working fluid state of the power module heat sink, the outlet working fluid state of the power module heat sink, the flow rate of the cooling fluid pump, and the back pressure valve opening. The current ambient temperature can be acquired through the vehicle cabin external temperature sensor or provided by the thermal management system controller. The power module thermal load can be determined based on the power module's input current, output current, bus voltage, switching frequency, modulation method, estimated chip junction temperature, and a pre-established loss model, or it can be inferred from the inlet and outlet temperature difference of the power module heat sink and the flow rate of the cooling fluid pump. The inlet working fluid state of the power module heat sink includes at least the inlet working fluid temperature and inlet pressure, and the outlet working fluid state includes at least the outlet working fluid temperature and outlet pressure, and may further include the estimated outlet dryness or the phase state judgment result obtained indirectly by the sensor. The control unit determines the target saturation temperature of the two-phase cooling medium based on the current ambient temperature. The target saturation temperature is not a fixed value but varies with the current ambient temperature. The setting principle is to ensure that the target saturation temperature is higher than the current ambient temperature and that the two-phase cooling medium has a heat transfer temperature difference on the condensation side that meets the heat release requirements. Subsequently, the control unit determines the target system saturation pressure based on the correlation between the saturation temperature and saturation pressure of the two-phase cooling medium. This correlation can be derived from a working fluid property database, a working fluid saturation temperature and saturation pressure table, experimental calibration data, or a pre-stored fitting curve by the control unit. The control unit compares the target system saturation pressure with the current operating pressure of the two-phase cooling circuit. When the system operating pressure is lower than the target system saturation pressure, the control unit controls the pressure regulating device of the gasbag reservoir to increase the internal pressure of the gasbag reservoir, thereby increasing the operating pressure of the two-phase cooling circuit system. When the system operating pressure is higher than the target system saturation pressure, the control unit controls the pressure regulating device of the gasbag reservoir to decrease the internal pressure of the gasbag reservoir, thereby decreasing the operating pressure of the two-phase cooling circuit system. Through the adjustment of the internal pressure of the gasbag reservoir, the system operating pressure of the two-phase cooling circuit approaches the target system saturation pressure, thus causing the system saturation temperature of the two-phase cooling working fluid to approach the target saturation temperature. Based on system-level pressure regulation, the control unit determines the inlet subcooling and outlet dryness of the power module radiator according to the power module heat load, the inlet working fluid state of the power module radiator, and the cooling fluid pump flow rate. Inlet subcooling characterizes the ability of the two-phase cooling fluid to absorb sensible heat before entering saturated evaporation. Outlet dryness characterizes the vapor content of the two-phase cooling fluid as it flows out of the power module radiator. Excessive outlet dryness indicates that a localized area within the power module radiator may be close to dryness, posing a risk of heat transfer deterioration and boiling. When the outlet dryness of the power module radiator exceeds the preset outlet dryness threshold, the control unit adjusts the back pressure valve to increase the downstream flow resistance of the power module radiator, thereby increasing the outlet pressure. With the increased outlet pressure, the inlet pressure of the power module radiator also increases accordingly. At this point, the saturation temperature of the two-phase cooling medium at the inlet also rises. If the inlet medium temperature remains relatively constant or changes only slightly, the inlet subcooling of the power module radiator increases. This increased inlet subcooling allows the inlet liquid medium to absorb more sensible heat before entering saturated evaporation, thus reducing the heat that needs to be borne by the latent heat of vaporization, and causing the outlet dryness to decrease. If the outlet dryness remains higher than the preset outlet dryness threshold after adjustment by the back pressure valve, the control unit further increases the pump flow rate of the circulating pump, reducing the heat load borne by the unit mass of the two-phase cooling medium, thereby causing the outlet dryness of the power module radiator to fall back to a safe range. The control unit also switches between the summer low-loss flow path, the summer high-loss flow path, and the winter heat pump heat exchange flow path via a flow path switching valve based on the current ambient temperature, power module heat load, and heat pump system heating demand. If the current ambient temperature is high and the power module heat load is low, it switches to the summer low-loss flow path. If the current ambient temperature is high and the power module heat load is high, it switches to the summer high-loss flow path. If the current ambient temperature is low and the heat pump system has heating demand, it switches to the winter heat pump heat exchange flow path. Each flow path switch synchronously updates the target saturation temperature, target system saturation pressure, back pressure valve opening, and pump flow rate, ensuring that the flow path switch is not an isolated action but rather works in conjunction with pressure regulation to achieve a comprehensive balance between heat exchange capacity and system energy consumption.

[0022] Example 3 details the system-level pressure regulation process of the airbag reservoir. This regulation process is mainly used to ensure that the two-phase cooling working fluid has a stable heat release driving force on the condensation side, especially to solve the problem of reduced condensation capacity of the external condenser in the vehicle under high-temperature environments; In this embodiment, the control unit acquires the current ambient temperature in real time or periodically; the current ambient temperature can be expressed as... The control unit determines the target saturation temperature based on the current ambient temperature and the target heat transfer temperature difference on the condenser side; the target saturation temperature can be expressed as... The target heat transfer temperature difference on the condenser side can be expressed as: The target saturation temperature can be determined according to the following relationship:

[0023] in, Indicates the target saturation temperature. Indicates the current ambient temperature. This represents the target heat transfer temperature difference on the condensing side. The reason for setting this relationship is that the two-phase cooling medium needs to release heat to the outside air and complete condensation in the external condenser. If the saturation temperature of the two-phase cooling medium is lower than or close to the current ambient temperature, the external condenser lacks a sufficient heat transfer temperature difference, making it difficult to complete the condensation process stably. By ensuring the target saturation temperature is higher than the current ambient temperature and maintaining the preset target heat transfer temperature difference on the condensing side, a stable thermodynamic boundary can be provided for the heat release on the condensing side. The target heat exchange temperature difference on the condenser side can be determined based on the heat exchange area of ​​the external condenser, the capacity of the external fan, the vehicle speed, the condenser's windward conditions, the type of two-phase coolant, and the system's energy consumption target. For example, when the vehicle is traveling at high speed and the incoming airflow is strong, the target heat exchange temperature difference on the condenser side can be appropriately reduced to decrease the system operating pressure and pressure difference loss; when the vehicle is traveling at low speed, starting after being idle at high temperature, or when the external condenser's heat exchange capacity is weak, the target heat exchange temperature difference on the condenser side can be appropriately increased to ensure a stable condensation process. After determining the target saturation temperature, the control unit determines the target system saturation pressure based on the correspondence between the saturation temperature and saturation pressure of the two-phase cooling medium. The target system saturation pressure can be expressed as... If the two-phase cooling working fluid is a low-pressure, environmentally friendly, and insulating working fluid, the control unit can look up the saturation pressure corresponding to the target saturation temperature based on the pre-stored working fluid property table, or determine the target system saturation pressure based on the pre-calibrated saturation pressure calculation model. The control unit acquires the current system operating pressure of the two-phase cooling circuit. This pressure can be obtained through pressure sensors located at the gasbag reservoir, circulating pump outlet, external condenser inlet, or representative locations within the two-phase cooling circuit. The control unit compares the current system operating pressure with the target system saturation pressure. If the current system operating pressure is lower than the target system saturation pressure, the control unit controls the gasbag reservoir pressure regulating device to increase the gas pressure on the gasbag side of the gasbag reservoir, thus increasing the internal pressure of the gasbag reservoir. Since the gasbag reservoir is connected to the two-phase cooling circuit, the increased internal pressure of the gasbag reservoir will drive an increase in the system pressure of the two-phase cooling circuit, causing the system saturation temperature of the two-phase cooling fluid to rise synchronously. If the current system operating pressure is higher than the target system saturation pressure, the control unit controls the gasbag reservoir pressure regulating device to release or reduce the pressure on the gasbag side of the gasbag reservoir, thus reducing the system pressure of the two-phase cooling circuit and correspondingly lowering the system saturation temperature.

[0024] In a preferred embodiment, the pressure regulating device for the gas reservoir can be an air compressor, a gas pressure regulating valve, a gas storage tank pressure regulating assembly, or an electronically controlled pressure regulating assembly. The control unit can employ a closed-loop control method to gradually bring the system operating pressure closer to the target system saturation pressure. During the closed-loop control process, a pressure allowable deviation range can be set to avoid frequent start-stop of the gas reservoir pressure regulating device. The control unit can also, in conjunction with the system energy consumption target, minimize the target system saturation pressure while meeting the heat exchange temperature difference on the condenser side, thereby reducing the pressure rise demand of the circulating pump and the system pressure burden.

[0025] In this embodiment, the airbag reservoir is no longer merely a component for storing liquid and buffering changes in volume, but rather a system-level pressure regulation actuator. Its regulation target is directly related to ambient temperature and the heat exchange temperature difference on the condenser side, thus enabling the two-phase cooling system of the automotive motor controller to adapt to condensation requirements under different ambient temperatures.

[0026] Example 4 details the process by which the back pressure valve regulates the inlet and outlet pressures, internal pressure drop, inlet subcooling, and outlet dryness of the power module radiator. This regulation process is primarily used to address the issues of localized drying within the power module radiator and excessively high outlet dryness when the power module's heat load increases. In this embodiment, the control unit acquires the inlet working fluid temperature of the power module heatsink, the inlet pressure of the power module heatsink, the outlet pressure of the power module heatsink, and the opening degree of the back pressure valve. The inlet pressure can be expressed as... The control unit determines the saturation temperature corresponding to the inlet pressure based on the physical property relationship between the inlet pressure and the two-phase cooling medium. This saturation temperature can be expressed as... The inlet working fluid temperature of the power module heatsink can be expressed as: ; The subcooling at the inlet of the power module heatsink can be expressed as: It is determined according to the following relationship:

[0027] in, Indicates the subcooling at the inlet of the power module heatsink. This indicates the saturation temperature corresponding to the inlet pressure of the power module heatsink. This indicates the inlet working fluid temperature of the power module heat sink. The greater the inlet subcooling, the greater the temperature margin of the liquid working fluid entering the power module heat sink from the saturated evaporation state, and the more sensible heat it can absorb before a significant phase change occurs. This sensible heat absorption capacity helps to suppress premature local vaporization and excessively rapid dryness growth within the power module heat sink. The control unit determines the outlet dryness fraction of the power module radiator based on the power module's heat load, the cooling fluid pump flow rate, the inlet subcooling, and the latent heat of vaporization of the two-phase cooling fluid. The power module's heat load can be expressed as Q, and the cooling fluid mass flow rate can be expressed as... The isobaric specific heat capacity of a liquid-phase cooling working fluid can be expressed as: The latent heat of vaporization of a two-phase cooling working fluid can be expressed as: The dryness of the power module heatsink outlet can be expressed as: Export dryness can be estimated according to the following relationship:

[0028] in, This indicates the dryness of the power module heatsink outlet, and Q represents the heat load of the power module.

[0029] Indicates the mass flow rate of the cooling working fluid. This indicates the isobaric specific heat capacity of the liquid-phase cooling working fluid. Indicates the subcooling at the inlet of the power module heatsink. This represents the latent heat of vaporization of the two-phase cooling working fluid. In this relationship, This represents the sensible heat that the subcooled liquid working fluid entering the power module heat sink can absorb before it reaches saturation. This represents the amount of heat that needs to be absorbed by the latent heat of phase change after deducting sensible heat absorption, divided by... The average dryness of the export can then be obtained; when When the value is less than zero, it means that the heat absorption capacity is already able to cover the current heat load of the power module. At this time, the outlet dryness can be set to zero, indicating that there has not yet been a significant increase in steam dryness at the outlet of the power module radiator.

[0030] The control unit compares the outlet dryness with a preset outlet dryness threshold. The preset outlet dryness threshold can be expressed as... In a preferred embodiment, The threshold is set to no more than 0.3. This threshold is set because if the outlet dryness of the power module heatsink is too high, localized areas may experience thinning of the liquid film, dry spots on the wall, deterioration of heat transfer, or even boiling. By controlling the outlet dryness within a low range, the stability and safety margin of the evaporative heat transfer in the power module heatsink can be improved. when Greater than At this time, the control unit adjusts the back pressure valve to increase the downstream flow resistance of the power module radiator. Since the back pressure valve is located downstream of the power module radiator, the increased flow resistance leads to higher outlet and inlet pressures, and consequently, a higher saturation temperature corresponding to the inlet pressure. If the inlet working fluid temperature of the power module radiator changes little in a short time, the inlet subcooling increases. With increased inlet subcooling, the subcooled liquid working fluid entering the power module radiator can absorb more sensible heat first, reducing the heat that needs to be absorbed through latent heat of vaporization within the radiator, thereby reducing the outlet dryness. when Not greater than At this time, the control unit maintains the current back pressure valve opening, or, under the condition of meeting the outlet dryness safety requirements, controls the back pressure valve to adjust in the direction of reducing the downstream flow resistance of the power module heat sink, so as to reduce the pressure rise demand of the circulating pump and reduce system energy consumption. If the outlet dryness is still greater than the preset outlet dryness threshold after the back pressure valve adjustment, the control unit further increases the circulating pump flow rate, so that the heat load borne by the unit mass of two-phase cooling working fluid is reduced, and the outlet dryness is caused to fall back to below the preset outlet dryness threshold.

[0031] In this embodiment, the back pressure valve is no longer merely a standard throttling or pressure-stabilizing component, but rather a unit for regulating the local evaporation pressure of the power module's radiator. Its regulation targets are directly related to the power module's heat load, inlet subcooling, and outlet dryness, thus enabling proactive control of the risk of localized drying under high heat flux density conditions.

[0032] Example 5 provides a detailed description of the summer low-loss flow path. The summer low-loss flow path is suitable for operating conditions where the ambient temperature is high, but the thermal load on the automotive motor controller power module is relatively low. For example, the summer low-loss flow path can be used when the vehicle is in a high-speed cruising, stable driving, light-load driving, or when the power module is operating with low losses. Under this operating condition, the control unit determines that the current ambient temperature is higher than the preset ambient temperature threshold and that the heat load of the vehicle motor controller power module is lower than the preset heat load threshold. At this time, the main control objectives of the system include ensuring sufficient heat exchange temperature difference on the condenser side, reducing the enthalpy of the cooling medium entering the external condenser, reducing the energy consumption of the external fan, and avoiding unnecessary back pressure loss. In actual operation, the two-phase cooling medium flows out of the gas-filled reservoir and enters the filter. The filter removes impurities from the medium and reduces the adverse effects of bubbles or local flash evaporation on the inlet of the circulating pump. After filtration, the two-phase cooling medium enters the circulating pump, which pressurizes the medium and provides the driving force for circulation. The liquid phase medium at the outlet of the circulating pump enters the regenerator via a flow path switching valve. In the regenerator, the low-temperature liquid phase medium at the outlet of the circulating pump exchanges heat with the high-temperature two-phase cooling medium from the outlet of the power module radiator. After heat exchange in the regenerator, the two-phase cooling medium enters the power module radiator and absorbs the heat generated by the vehicle motor controller power module. Because the power module's heat load is low under this condition, the dryness of the power module radiator outlet typically does not rise rapidly above the preset outlet dryness threshold. The high-temperature two-phase cooling medium exiting the power module radiator re-enters the regenerator via a back pressure valve, releasing some heat to the low-temperature liquid phase working medium at the circulation pump outlet. After releasing some heat, the high-temperature two-phase cooling medium then enters the external condenser via a flow path switching valve. Under the action of the external fan and the incoming airflow from the vehicle, the external condenser causes the two-phase cooling medium to release heat and condense to the external environment. The condensed medium then flows back to the airbag reservoir, completing one cycle. In the low-loss flow path during summer, the pressure regulation device of the airbag reservoir still determines the target saturation temperature and target system saturation pressure based on the current ambient temperature, and adjusts the internal pressure of the airbag reservoir to make the system operating pressure of the two-phase cooling circuit approach the target system saturation pressure. This ensures that the external condenser still has a condensation-side heat exchange temperature difference that meets the heat release requirements under high-temperature conditions. In this operating condition, the back pressure valve is mainly used to maintain the outlet dryness of the power module radiator within a safe range. When the control unit determines that the outlet dryness is lower than the preset outlet dryness threshold, the back pressure valve can maintain a small pressure adjustment range to reduce the downstream flow resistance of the power module radiator and reduce the power consumption of the circulating pump. When the outlet dryness rises due to local heat load changes and approaches the preset outlet dryness threshold, the control unit can appropriately increase the opening adjustment intensity of the back pressure valve to increase the evaporation section pressure and inlet subcooling, preventing the outlet dryness from rising further. The key to this embodiment lies in the fact that the low-loss flow path in summer does not simply utilize a regenerator for heat exchange, but rather achieves synergy between the system-level pressure regulation of the gasbag reservoir, the local pressure regulation of the back pressure valve, and the regenerator flow path. The regenerator reduces the enthalpy of the cooling medium entering the external condenser, the pressure regulation device of the gasbag reservoir ensures the temperature difference for heat exchange on the condenser side, and the back pressure valve maintains a safe dryness level at the outlet of the power module radiator. Through this synergy, the system can meet the heat dissipation requirements of the power module while reducing the heat load of the external condenser, the energy consumption of the external fan, and the additional energy consumption of the circulating pump.

[0033] Example 6: This example provides a detailed description of the high-loss flow path in summer. The high-loss flow path in summer is suitable for operating conditions where the ambient temperature is high and the power module of the automotive motor controller has a high thermal load. For example, it can be used when the vehicle is accelerating, climbing, operating at high speed and high load, undergoing prolonged high-power output, or when the electric drive system frequently outputs high torque. Under this operating condition, the control unit determines that the current ambient temperature is higher than the preset ambient temperature threshold and that the heat load of the vehicle motor controller power module is not lower than the preset heat load threshold. At this time, the main control objectives of the system include ensuring that the external condenser has effective condensation capacity, increasing the subcooling at the inlet of the power module radiator, reducing the dryness at the outlet of the power module radiator, suppressing local evaporation, and avoiding boiling crisis. In actual operation, the two-phase cooling working fluid flows out of the gas-filled reservoir and passes through a filter and a circulating pump in sequence. After the circulating pump pressurizes the two-phase cooling working fluid, a flow path switching valve switches the working fluid to a bypass path to the regenerator. This causes the subcooled liquid phase working fluid at the circulating pump outlet to no longer preferentially enter the regenerator, but instead directly enters the power module radiator. Since the working fluid is not preheated by the high-temperature two-phase working fluid at the power module radiator outlet in the regenerator, the working fluid entering the power module radiator maintains a high degree of subcooling. This high degree of subcooling allows the working fluid to absorb more sensible heat first in the power module radiator before entering the saturated evaporation stage, thereby increasing the total heat absorption capacity. After absorbing a large amount of heat generated by the vehicle motor controller power module, the two-phase cooling medium flowing out of the power module radiator enters the back pressure valve. The control unit estimates the outlet dryness of the power module radiator based on the power module heat load, pump flow rate, inlet subcooling, and latent heat of vaporization of the two-phase cooling medium. When the outlet dryness exceeds a preset outlet dryness threshold, the control unit adjusts the back pressure valve to increase downstream flow resistance, thereby increasing the pressure in the evaporation section of the power module radiator and increasing the inlet subcooling. Increased inlet subcooling enhances the sensible heat absorption capacity of the working medium, reducing the outlet dryness. If the outlet dryness remains high after adjusting the back pressure valve, the control unit increases the circulation pump flow rate, reducing the heat load borne by the unit mass of two-phase cooling medium and further controlling the outlet dryness. The two-phase coolant, after exiting the back pressure valve, enters the external condenser via a flow path switching valve. The external condenser condenses the two-phase coolant under the action of the external fan and the incoming airflow from the vehicle. The condensed coolant then flows back to the airbag reservoir. Due to the high ambient temperature and large heat load of the power module during high-loss summer operation, the airbag reservoir pressure control device needs to actively increase the system saturation pressure and temperature based on the current ambient temperature to ensure the external condenser maintains a sufficient heat exchange temperature difference to meet heat dissipation requirements. Simultaneously, the control unit can adjust the external fan speed according to the condenser outlet status and system energy consumption target to coordinate with the target system saturation pressure control.

[0034] The key to this embodiment lies in the fact that the high-loss flow path in summer is not simply about increasing the pump flow rate or bypassing the regenerator, but rather about achieving outlet dryness control through the synergy of bypassing the regenerator, local pressure regulation by the back pressure valve, system-level pressure regulation by the gasbag reservoir, and pump flow rate adjustment. The bypass regenerator directly increases the inlet subcooling, the back pressure valve further increases the inlet subcooling by increasing the evaporator section pressure, pump flow rate adjustment reduces the heat load per unit mass of working fluid, and pressure regulation by the gasbag reservoir ensures sufficient condensing capacity for the external condenser. Through this synergy, the system can effectively suppress localized drying and ensure safe junction temperatures for the power modules under high heat flux density conditions.

[0035] Example 7: This example provides a detailed description of the winter heat pump heat exchange path. The winter heat pump heat exchange path is suitable for operating conditions where the ambient temperature is low and the heat pump system has a heating requirement. For example, it can be used when a vehicle starts in a low-temperature environment, the passenger compartment needs heating, the external evaporator has insufficient heat absorption capacity, or the heat pump system's heating efficiency decreases. Under this operating condition, the control unit determines that the current ambient temperature is not higher than the preset ambient temperature threshold and that the heat pump system has a heating demand. At this time, the main control objectives of the system include not only ensuring the heat dissipation of the vehicle motor controller power module, but also transferring the waste heat of the power module to the heat pump system to reduce the heating energy consumption of the heat pump system and expand the operating range of the heat pump system in low-temperature environments; During operation, the two-phase coolant flows out of the airbag reservoir and passes through a filter and a circulation pump in sequence. The circulation pump pressurizes the two-phase coolant and then it enters the power module radiator through a flow path switching valve. In the power module radiator, the two-phase coolant absorbs the heat generated by the vehicle motor controller power module. The two-phase coolant flowing out of the power module radiator enters the plate heat exchanger through a back pressure valve and a flow path switching valve. In the plate heat exchanger, the two-phase coolant exchanges heat with the refrigerant or heat pump heat exchange medium on the heat pump system side, transferring the waste heat from the power module to the heat pump system. When the heat pump system is in heating mode, the high-temperature, high-pressure refrigerant discharged from the compressor enters the cabin condenser and releases heat to the passenger compartment. After being throttled and depressurized by the expansion valve, the refrigerant can be diverted to the external evaporator and plate heat exchanger. In the external evaporator, the refrigerant absorbs heat from the ambient environment; in the plate heat exchanger, the refrigerant absorbs waste heat released from the power module in the two-phase cooling circuit. The refrigerant, after absorbing heat, returns to the compressor, completing the heat pump cycle. Introducing waste heat from the power module through the plate heat exchanger reduces the heat pump system's dependence on heat absorption from the low-temperature air outside the cabin, thus improving the system's low-temperature heating capacity. In the winter heat pump heat exchange path, the pressure regulation device of the gasbag receiver still adjusts the system saturation pressure of the two-phase cooling circuit according to the current ambient temperature and heat exchange requirements. Due to the low ambient temperature in winter, the external condenser has a large natural heat exchange temperature difference, but the system still needs to avoid excessively low operating pressure that could lead to unstable working fluid flow, unstable pump inlet conditions, or uncontrollable phase states on the plate heat exchanger side. Therefore, the control unit determines the target saturation temperature and target system saturation pressure based on the heat absorption requirements of the heat pump system, the heat exchange capacity of the plate heat exchanger, and the heat load of the power module, and maintains system pressure stability through the gasbag receiver pressure regulation device.

[0036] In winter, the back pressure valve is used in the heat pump heat exchange path to maintain a stable evaporative heat exchange state within the power module radiator. If the power module's heat load is high or the outlet dryness is close to the preset outlet dryness threshold, the control unit increases the evaporation section pressure and inlet subcooling within the power module radiator through the back pressure valve to prevent localized drying. If the power module's heat load is low, the control unit can reduce the back pressure valve's pressure regulation intensity to reduce the power consumption of the circulating pump. The flow path switching valve can adjust the flow distribution of the two-phase cooling medium into the plate heat exchanger and the external condenser based on the heat absorption demand of the heat pump system and the condensation demand of the two-phase cooling circuit. When the heat pump system's heating demand is high, more of the two-phase cooling medium is prioritized to enter the plate heat exchanger for waste heat recovery; when the heat pump system's heating demand decreases or the plate heat exchanger's heat exchange capacity is insufficient, some of the two-phase cooling medium can be allowed to enter the external condenser for auxiliary condensation. Through this method, the heat pump heat exchange flow path in winter can balance the heat dissipation safety of the power module and the thermal management efficiency of the entire vehicle.

[0037] The key to this embodiment lies in the fact that the heat pump heat exchange path in winter does not simply connect the waste heat from the power module to the heat pump system, but rather forms a synergy between pressure regulation of the gasbag receiver, local pressure adjustment of the back pressure valve, and waste heat recovery from the plate heat exchanger. Pressure regulation of the gasbag receiver ensures the stability of the system's saturation pressure and phase state; the back pressure valve ensures the safety of the power module radiator outlet dryness; the plate heat exchanger introduces the waste heat from the power module into the heat pump system; and the flow path switching valve allocates the heat exchange path according to the heat pump's needs. Therefore, the system can simultaneously improve the heat dissipation reliability of the power module and the heating efficiency of the heat pump system in low-temperature winter environments.

[0038] Example 8: This example provides a detailed explanation of the switching logic between the low-loss flow path in summer, the high-loss flow path in summer, and the heat pump heat exchange flow path in winter. The control unit first acquires the current ambient temperature, the heat load of the power module of the new energy vehicle motor controller, and the heating demand of the heat pump system. The control unit presets ambient temperature thresholds and heat load thresholds; the ambient temperature threshold is used to distinguish between high-temperature and low-temperature environments, and the heat load threshold is used to distinguish between low-loss and high-loss operating conditions of the power module; the ambient temperature threshold and heat load threshold can be determined based on the vehicle thermal management system calibration results, the thermal safety boundary of the power module, the heat exchange capacity of the external condenser, and the physical properties of the two-phase coolant. If the current ambient temperature is higher than the preset ambient temperature threshold, and the heat load of the vehicle motor controller power module is lower than the preset heat load threshold, the control unit switches to the summer low-loss flow path. When switching to the summer low-loss flow path, the control unit simultaneously determines the target saturation temperature and the target system saturation pressure, and controls the airbag reservoir pressure regulating device to adjust the system operating pressure to near the target system saturation pressure; the control unit also controls the back pressure valve to maintain a low flow resistance and makes small adjustments based on the outlet dryness safety margin; at the same time, the control unit makes the two-phase cooling working fluid flow through the regenerator to reduce the enthalpy of the working fluid entering the external condenser and the energy consumption of the external fan; If the current ambient temperature is higher than the preset ambient temperature threshold, and the heat load of the vehicle motor controller power module is not lower than the preset heat load threshold, the control unit switches to the summer high-loss flow path. When switching to the summer high-loss flow path, the control unit simultaneously increases the control priority of inlet subcooling and outlet dryness. The control unit bypasses the regenerator and directly enters the power module radiator to maintain a high inlet subcooling. The control unit also adjusts the back pressure valve opening according to the deviation of the outlet dryness from the preset outlet dryness threshold, and increases the circulation pump flow rate when necessary. The airbag reservoir pressure regulation device increases or maintains the target system saturation pressure according to the ambient temperature to ensure that the external condenser has sufficient condensation capacity. When the current ambient temperature is not higher than the preset ambient temperature threshold and the heat pump system has a heating demand, the control unit switches to the winter heat pump heat exchange path. When switching to the winter heat pump heat exchange path, the control unit directs the two-phase cooling medium to absorb heat through the power module radiator and then into the plate heat exchanger, transferring the waste heat from the power module to the heat pump system. The control unit determines the flow distribution of the plate heat exchanger and the auxiliary condensation ratio of the external condenser based on the heat absorption demand of the heat pump system, the heat load of the power module, and the status of the two-phase cooling circuit. The control unit also simultaneously updates the target saturation temperature, target system saturation pressure, back pressure valve opening, and pump flow rate to maintain a balance between the heat exchange capacity and energy consumption of the two-phase cooling circuit and the heat pump system. During operating condition switching, the control unit can set hysteresis conditions and switching delays to avoid frequent flow path switching caused by fluctuations in the current ambient temperature or power module heat load near thresholds. For example, the control unit can require the power module heat load to continuously exceed a preset heat load threshold for a preset time before switching from the summer low-loss flow path to the summer high-loss flow path; it can also require the outlet dryness to continuously fall below a preset outlet dryness threshold for a preset time before reducing the back pressure valve's pressure regulation intensity or reducing the circulating pump flow rate. By using hysteresis conditions and switching delays, the system's operational stability can be improved and frequent valve operations can be reduced.

[0039] In this embodiment, each flow path switch synchronously updates the pressure regulation target and the pump valve control target. That is, flow path switching does not simply change the coolant path, but rather adjusts in conjunction with the target saturation temperature, target system saturation pressure, back pressure valve opening, and pump flow rate. Therefore, this embodiment achieves a multi-condition coordinated operation strategy.

[0040] Example 9: This example provides a detailed description of the coordinated control between the target saturation temperature, inlet subcooling, outlet dryness, pump flow rate, and back pressure valve opening. In this embodiment, the control unit uses the target saturation temperature as the condenser-side control variable, the inlet subcooling as the evaporator inlet control variable, the outlet dryness as the evaporator outlet safety control variable, the pump flow rate as the unit mass heat load adjustment variable, and the back pressure valve opening as the evaporator pressure adjustment variable. These variables are interconnected; the target saturation temperature determines the condensation heat transfer boundary of the two-phase cooling medium under system-level pressure; the inlet subcooling determines the sensible heat absorption capacity of the medium after entering the power module radiator; the outlet dryness reflects the evaporation heat transfer safety state; the pump flow rate affects the heat carried by the unit mass of the medium; and the back pressure valve opening affects the inlet and outlet pressures, internal pressure drop, and inlet subcooling within the power module radiator. The control unit first determines the target saturation temperature and target system saturation pressure based on the current ambient temperature, and then regulates the system-level pressure through the pressure regulation device of the gas-filled liquid reservoir. At this time, the control objective is to ensure that there is a sufficient heat exchange temperature difference on the condenser side; if the current ambient temperature rises, the control unit increases the target saturation temperature and the target system saturation pressure; if the current ambient temperature decreases, the control unit can reduce the target system saturation pressure while ensuring condensation stability, so as to reduce the system pressure burden and pump power consumption. The control unit then determines the heat load per unit mass of the power module radiator based on the power module's heat load and pump flow rate. When the power module's heat load increases or the pump flow rate decreases, the heat load borne by the working fluid per unit mass increases, and the outlet dryness tends to increase. In this case, the control unit can prioritize increasing the inlet and outlet pressures and inlet subcooling through the back pressure valve to increase the sensible heat absorption capacity. If the outlet dryness is still higher than the preset outlet dryness threshold, the control unit increases the circulation pump flow rate to reduce the heat load borne by the working fluid per unit mass. If the outlet dryness is much lower than the preset outlet dryness threshold, and the power module junction temperature is within a safe range, the control unit can reduce the circulation pump flow rate or reduce the back pressure valve's pressure regulation intensity to reduce system energy consumption.

[0041] In the low-loss flow path during summer, the collaborative control strategy prioritizes system energy consumption. The control unit, while ensuring safe heat exchange temperature difference and outlet dryness on the condenser side, controls the regenerator to participate in heat exchange to reduce the heat load on the external condenser; simultaneously, it reduces the back pressure valve's pressure regulation intensity and pump flow rate to keep the energy consumption of the circulating pump and external fan at a low level. In high-loss flow paths during summer, the coordinated control strategy prioritizes thermal safety. The control unit bypasses the regenerator to increase the inlet subcooling and increases the evaporation section pressure via the back pressure valve. If the outlet dryness fraction is still too high, the pump flow rate is increased. At this point, the target saturation temperature, inlet subcooling, outlet dryness fraction, pump flow rate, and back pressure valve opening all work together to suppress localized drying and ensure the safe junction temperature of the power module. In the winter heat pump heat exchange path, a coordinated control strategy balances thermal safety and waste heat utilization. The control unit maintains stable system pressure through the pressure regulation device of the gas-filled liquid reservoir, maintains a safe dryness level at the outlet of the power module radiator through the back pressure valve, and allows the two-phase cooling working fluid to enter the plate heat exchanger through the flow path switching valve, transferring the waste heat from the power module to the heat pump system. If the heat absorption demand of the heat pump system increases, the control unit can increase the flow rate of the working fluid entering the plate heat exchanger; if the heat load of the power module increases, the control unit simultaneously increases the pressure regulation intensity of the back pressure valve or the pump flow rate to prevent the outlet dryness level from exceeding the threshold.

[0042] In this embodiment, the control unit does not independently control the airbag reservoir pressure, back pressure valve opening, pump flow rate, and flow path switching. Instead, it coordinates these parameters based on the relationship between the condenser-side heat exchange temperature difference, inlet subcooling, outlet dryness, and system energy consumption. This coordinated control method improves the adaptability of the automotive motor controller's two-phase cooling system across a wide range of ambient temperatures and power loads.

[0043] Example 10 describes a preferred embodiment of a two-phase cooling medium, a circulating pump, a pressure regulating device for an air-filled liquid reservoir, a back pressure valve, a regenerator, and a plate heat exchanger.

[0044] The preferred two-phase cooling medium is a low-pressure, environmentally friendly, and insulating medium. For example, R1233zd(E) can be used, or other mediums that meet the requirements for safety, insulation, environmental friendliness, and phase change heat transfer performance can be used. The reason for choosing an insulating medium is that the power module of the motor controller in new energy vehicles is a high-voltage electrical component, and an insulating medium can reduce the risk of electrical short circuits caused by medium leakage or partial failure of the radiator. Choosing a low-pressure medium can reduce the system pressure requirements, improve the safety of vehicle applications, and enhance engineering adaptability. Gear pumps or other positive displacement pumps suitable for circulating low-pressure two-phase working fluids are preferred for the circulation pump. Gear pumps can provide a stable flow rate for the two-phase cooling working fluid and adapt to flow regulation requirements under a wide range of operating conditions. A filter is installed on the inlet side of the circulation pump to reduce the impact of impurities on pump body wear and to reduce the risk of cavitation or flow fluctuations caused by air bubbles entering the pump suction inlet. The pressure regulation device for the airbag reservoir can be an air compressor, a gas pressure regulating valve, a gas storage tank pressure regulating assembly, or an electronically controlled pressure regulating device consisting of an air pump, a pressure regulating valve, and a pressure sensor. The airbag reservoir can be equipped with a flexible airbag or diaphragm structure, allowing changes in gas-side pressure to act on the cooling medium side, thereby altering the pressure of the two-phase cooling circuit system. The pressure regulation device is controlled by a control unit, and its regulation target is to bring the system operating pressure close to the target system saturation pressure. The back pressure valve is preferably an electronically controlled back pressure valve, whose opening degree can be continuously or steppedly adjusted according to the command output by the control unit. The back pressure valve is located downstream of the power module radiator and can adjust the inlet and outlet pressures and internal pressure drop of the power module radiator by changing the flow resistance on the outlet side of the power module radiator. The control objective of the back pressure valve is not to simply maintain a fixed outlet pressure, but to dynamically adjust the evaporation section pressure according to the heat load of the power module, the inlet subcooling degree and the outlet dryness threshold. The regenerator can be a plate-fin heat exchanger, a shell-and-tube heat exchanger, a microchannel heat exchanger, or other compact heat exchangers. The regenerator is mainly used in low-loss conditions during summer to release some heat from the high-temperature two-phase working fluid at the power module radiator outlet to the low-temperature liquid-phase working fluid at the circulating pump outlet, thereby reducing the enthalpy of the working fluid entering the external condenser, reducing the load on the external condenser and the power consumption of the external fan. Plate heat exchangers can be brazed plate heat exchangers, microchannel heat exchangers, or other compact heat exchangers suitable for vehicle installation. They are used to transfer heat between the two-phase cooling circuit and the heat pump system during winter operation, allowing waste heat from the power module to assist the heat pump system in heating. Plate heat exchangers can be arranged in parallel with the external condenser, or in series or by bypass depending on the vehicle's thermal management system architecture.

[0045] In this embodiment, the components can be replaced equivalently based on the vehicle layout space, power module heat load level, coolant type, and system energy consumption target. Any system can achieve adjustment of system saturation pressure according to ambient temperature, adjustment of evaporator section pressure and inlet subcooling according to power module heat load and outlet dryness threshold, and coordinated flow path switching under low-loss summer, high-loss summer, and winter heat pump heat exchange conditions.

[0046] Example 11 provides a general description of the scope of application of the present invention.

[0047] The present invention applies to new energy transportation vehicles, specifically including but not limited to new energy vehicles, new energy special vehicles, new energy construction machinery, flying cars, electric vertical take-off and landing aircraft, low-altitude drones, etc.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A control method for a power module cooling system of a new energy vehicle, characterized in that, The two-phase cooling system for the power module of the motor controller in new energy vehicles includes the following steps: S1. Obtain the current ambient temperature, power module heat load, power module radiator inlet working fluid status, power module radiator outlet working fluid status, cooling fluid pump flow rate, and back pressure valve opening. S2. Determine the target saturation temperature of the cooling working fluid based on the current ambient temperature, and determine the target system saturation pressure based on the target saturation temperature; S3. The pressure regulation device of the airbag reservoir adjusts the internal pressure of the airbag reservoir so that the system operating pressure of the two-phase cooling circuit approaches the target system saturation pressure, so that the cooling working fluid forms a heat exchange temperature difference on the condensation side that meets the heat release requirements. S4. Determine the subcooling degree at the inlet of the power module radiator and the dryness degree at the outlet of the power module radiator based on the heat load of the power module, the working fluid state at the inlet of the power module radiator and the flow rate of the cooling working fluid pump. S5. Based on the comparison between the outlet dryness of the power module heat sink and the preset outlet dryness threshold, adjust the opening of the back pressure valve to actively regulate the outlet pressure of the power module heat sink, thereby regulating the inlet pressure, internal pressure drop and inlet subcooling of the power module heat sink. S6. Based on the current ambient temperature and power module heat load, switch between the low-loss flow path in summer, the high-loss flow path in summer, and the heat pump coupling flow path in winter through the flow path switching valve.

2. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The step of determining the target saturation temperature of the cooling medium based on the current ambient temperature, and determining the target system saturation pressure based on the target saturation temperature, includes: Based on the current ambient temperature and the target heat exchange temperature difference on the condenser side, a target saturation temperature higher than the current ambient temperature is determined. Based on the correspondence between the saturation temperature and saturation pressure of the cooling medium, determine the target system saturation pressure corresponding to the target saturation temperature; The target heat exchange temperature difference on the condensing side is used to ensure that the cooling working fluid can release heat to the external environment and condense in the external condenser.

3. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The pressure regulating device for the airbag reservoir adjusts the internal pressure of the airbag reservoir, including: When the system operating pressure of the two-phase cooling circuit is lower than the target system saturation pressure, the pressure regulating device of the airbag reservoir is controlled to increase the internal pressure of the airbag reservoir. When the system operating pressure of the two-phase cooling circuit is higher than the target system saturation pressure, the pressure regulation device of the airbag reservoir is controlled to reduce the internal pressure of the airbag reservoir. The system operating pressure of the two-phase cooling circuit is changed by altering the internal pressure of the gas-filled reservoir, and the system saturation temperature of the cooling medium is changed simultaneously.

4. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The determination of the inlet subcooling of the power module heat sink and the outlet dryness of the power module heat sink includes: The inlet subcooling of the power module heat sink is determined based on the inlet working fluid temperature of the power module heat sink and the corresponding saturation temperature under the current inlet pressure. The outlet dryness of the power module radiator is determined based on the power module heat load, the cooling medium pump flow rate, the inlet subcooling of the power module radiator, and the latent heat of vaporization of the cooling medium under the target saturation pressure. Among them, the inlet subcooling of the power module radiator is used to characterize the sensible heat absorption capacity of the cooling medium before it enters the saturated evaporation state, and the outlet dryness of the power module radiator is used to characterize the steam content state of the cooling medium when it flows out of the power module radiator.

5. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The step of adjusting the back pressure valve opening based on the comparison result between the dryness of the power module heat sink outlet and the preset outlet dryness threshold includes: When the dryness of the power module heat sink outlet is not greater than the preset outlet dryness threshold, maintain the current back pressure valve opening, or reduce the downstream flow resistance of the power module heat sink to reduce system energy consumption under the condition of meeting the outlet dryness safety requirements. When the dryness of the power module heat sink outlet is greater than the preset outlet dryness threshold, the back pressure valve is controlled to adjust in the direction of increasing the downstream flow resistance of the power module heat sink, so as to increase the pressure of the working fluid at the outlet of the power module heat sink, and simultaneously increase the pressure of the subcooled working fluid at the inlet of the power module heat sink and increase the inlet subcooling of the power module heat sink. If the dryness of the power module radiator outlet is still greater than the preset outlet dryness threshold after adjustment by the back pressure valve, the pump flow rate of the circulating pump will be increased to reduce the heat load borne by the unit mass of cooling working fluid, so that the dryness of the power module radiator outlet falls back to below the preset outlet dryness threshold.

6. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The low-loss flow path in summer includes: The cooling medium is pressurized by the circulating pump and enters the regenerator, where it exchanges heat with the high-temperature two-phase cooling medium from the outlet of the power module heat sink. The cooling medium, after heat exchange in the regenerator, enters the power module radiator to absorb heat from the power module. The high-temperature two-phase cooling medium flowing out of the power module heat sink enters the regenerator again after passing through the back pressure valve to release some heat, and then enters the external condenser for condensation. In the low-loss flow path during summer, the pressure regulation device of the airbag reservoir is used to maintain the heat exchange temperature difference on the condenser side, the back pressure valve is used to maintain the dryness of the power module radiator outlet within a safe range, and the regenerator is used to reduce the enthalpy of the cooling medium entering the external condenser.

7. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The high-loss flow path in summer includes: The cooling medium is pressurized by the circulating pump, bypasses the regenerator, and directly enters the power module heat sink; The two-phase cooling medium flowing out of the power module radiator enters the external condenser for condensation via the back pressure valve and the flow path switching valve in sequence. In the high-loss flow path during summer, the subcooling at the inlet of the power module radiator is increased by bypassing the regenerator, the pressure in the evaporation section of the power module radiator is increased by adjusting the back pressure valve, and the dryness at the outlet of the power module radiator is reduced by adjusting the pump flow rate of the circulating pump.

8. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The winter heat pump coupling flow path includes: The cooling medium is pressurized by the circulating pump and then enters the power module heat sink to absorb the heat from the power module. The two-phase cooling medium flowing out of the power module radiator enters the plate heat exchanger via a back pressure valve and a flow path switching valve. The two-phase cooling medium exchanges heat with the heat pump system in the plate heat exchanger to transfer the waste heat from the power module to the heat pump system. In the winter heat pump coupling flow path, the airbag liquid reservoir pressure regulation device is used to maintain the system saturation pressure of the two-phase cooling circuit, the back pressure valve is used to maintain the stability of the evaporative heat exchange state in the power module radiator, and the plate heat exchanger is used for waste heat recovery to assist the heat pump system in heating.

9. The control method for a power module cooling system of a new energy vehicle according to claim 1, characterized in that, The process of switching between a low-loss flow path in summer, a high-loss flow path in summer, and a heat pump coupling flow path in winter, based on the current ambient temperature and the heat load of the power module, via a flow path switching valve, includes: When the current ambient temperature is higher than the preset ambient temperature threshold and the power module heat load is lower than the preset heat load threshold, switch to the summer low-loss flow path. When the current ambient temperature is higher than the preset ambient temperature threshold and the power module heat load is not lower than the preset heat load threshold, switch to the summer high loss flow path; When the current ambient temperature is not higher than the preset ambient temperature threshold and the heat pump system has a heating demand, switch to the winter heat pump coupling flow path. Each flow path switch synchronously updates the target saturation temperature, target system saturation pressure, back pressure valve opening, and pump flow rate.

10. A cooling system for a power module of a new energy vehicle, characterized in that, include: The air-filled liquid reservoir is used to store two-phase coolant and buffer the volume change caused by the phase change of the coolant. The airbag reservoir pressure regulating device is connected to the airbag reservoir and is used to regulate the internal pressure of the airbag reservoir. A circulating pump is used to drive the two-phase cooling medium to circulate within a two-phase cooling circuit. Power module heat sink, used to allow the two-phase cooling medium to absorb the heat generated by the automotive power module; The back pressure valve is located downstream of the power module heatsink and is used to regulate the flow resistance downstream of the power module heatsink. The regenerator is used to exchange heat between the cooling medium at the outlet of the circulating pump and the cooling medium at the outlet of the power module radiator under low-loss conditions in summer. An external condenser is used to condense a two-phase cooling medium that releases heat to the external environment. Plate heat exchangers are used to exchange heat between a two-phase cooling medium and a heat pump system. A flow path switching valve is used to switch between the low-loss flow path in summer, the high-loss flow path in summer, and the heat pump coupled flow path in winter. The control unit is connected to the airbag reservoir pressure regulating device, the circulating pump, the back pressure valve, and the flow path switching valve, respectively, and is used to execute the control method of the power module cooling system of a new energy vehicle as described in any one of claims 1 to 9.

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