Patent Publication Number: US-2022212517-A1

Title: Thermal management system, method for controlling thermal management system, and electric vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Chinese Patent Application No. 202110164688.7, filed on Feb. 5, 2021, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     This application relates to the field of thermal management technologies, and in particular, to a thermal management system, a method for controlling a thermal management system, and an electric vehicle. 
     BACKGROUND 
     In a conventional technology, there is a heating technology based on heating by a motor. Specifically, when heating is required, the motor is enabled to operate to heat a motor coolant, and the motor coolant transfers heat to a to-be-heated space or device, to heat the space or device. However, not all of heat generated by the motor is transferred to the motor coolant, but a part of the heat is dissipated to a surrounding environment of the motor through a motor housing or the like, thereby resulting in relatively low thermal efficiency of this heating mode. 
     A thermal management system for an electric vehicle is used as an example for description below. For example, a battery has a relatively low temperature in winter. In this case, the battery is usually heated. For a technology for heating the battery, there is a manner in which heat is generated through stalling or low-efficiency operating of a motor, to increase a temperature of a motor coolant, and then the battery is heated by the motor coolant. However, a part of the heat generated by the motor is dissipated to an environment through motor and gear box housings, and only a part of the heat is transferred to the motor coolant. In particular, a larger difference between a motor temperature and an ambient temperature results in greater heat loss caused by dissipation of the heat generated by the motor to the environment. As a result, utilization of the heat generated by the motor is relatively low. 
     In addition to the battery, a passenger compartment also has a heating requirement. Similarly, if the passenger compartment is heated based on heating by the motor, utilization of heat generated by the motor is also relatively low. 
     SUMMARY 
     In view of this, a main objective of this application is to provide a thermal management system capable of relatively efficiently using heat generated by a motor, a method for controlling a thermal management system, and an electric vehicle. 
     To achieve the foregoing objective, a first aspect of this application provides a thermal management system, including a refrigerant loop and a motor coolant loop. The refrigerant loop and the motor coolant loop jointly include a low pressure chiller. The low pressure chiller is configured to enable a refrigerant in the refrigerant loop to absorb heat from a motor coolant in the motor coolant loop, to heat a target temperature-controlled space and/or a target temperature-controlled device. 
     With the foregoing structure, the low pressure chiller enables the refrigerant in the refrigerant loop to absorb the heat from the motor coolant through evaporation, that is, the heat from the motor coolant is absorbed by a heat pump to heat the target temperature-controlled space and/or the target temperature-controlled device. Therefore, compared with a manner of directly heating the target temperature-controlled device or air in the target temperature-controlled space by the motor coolant, the target temperature-controlled space and/or the target temperature-controlled device can be heated to a required temperature even if a temperature of the motor coolant is relatively low, that is, the temperature of the motor coolant may be relatively low on a basis that a required heating effect can be achieved, so that a difference between the temperature of the motor coolant and an ambient temperature is relatively small. In this way, heat loss caused by dissipation of heat from a motor to a surrounding environment can be reduced, thereby improving utilization of the heat from the motor. 
     In an embodiment of the first aspect of this application, the refrigerant loop further includes: an outer heat exchanger, configured to enable heat exchange between the refrigerant and air outside the target temperature-controlled space, and connected in parallel to the low pressure chiller; and a 3-way valve, configured to adjust a refrigerant flow ratio between the low pressure chiller and the outer heat exchanger. 
     With the foregoing structure, heat is generated both in a manner of providing heat by the motor and a manner of providing heat by external air, and the 3-way valve adjusts a heat supply amount shared by each of the motor and the external air. For example, when the ambient temperature is relatively high, the heat provided by the motor is reduced, thereby reducing energy consumption (because heat conversion efficiency of the motor is relatively low); or when the ambient temperature is relatively low (lower than −10° C.), or when the outer heat exchanger is frosted after long-term use, a flow rate of the low pressure chiller is increased, to increase a heat supply amount shared by the motor, thereby avoiding an insufficient heating amount. 
     In an embodiment of the first aspect of this application, the 3-way valve includes: a first electronic expansion valve, connected in series to the low pressure chiller, and configured to adjust a refrigerant flow rate of the low pressure chiller; and a second electronic expansion valve, connected in series to the outer heat exchanger, and configured to adjust a refrigerant flow rate of the outer heat exchanger. 
     With the foregoing structure, the 3-way valve is constituted by the electronic expansion valves. This has lower costs than, for example, a manner of using a three-way valve with an adjustable flow rate. 
     In an embodiment of the first aspect of this application, the refrigerant loop further includes: a heat exchanger for the target temperature-controlled device, configured to enable heat exchange between the refrigerant and a heat exchange working medium for adjusting a temperature of the target temperature-controlled device; an inner heat exchanger, configured to enable heat exchange between the refrigerant and air in the target temperature-controlled space; a third electronic expansion valve, connected in series to the heat exchanger for the target temperature-controlled device, and configured to control a refrigerant flow rate of the heat exchanger for the target temperature-controlled device; and a fourth electronic expansion valve, connected in series to the inner heat exchanger, and configured to control a refrigerant flow rate of the inner heat exchanger. The first electronic expansion valve, the second electronic expansion valve, the third electronic expansion valve, and the fourth electronic expansion valve may be integrated. 
     With the foregoing structure, the plurality of electronic expansion valves are integrated, thereby reducing manufacturing costs. 
     In an embodiment of the first aspect of this application, the refrigerant loop further includes: a compressor that has a refrigerant outlet and a refrigerant inlet; a first outlet branch, configured to connect the refrigerant outlet to the low pressure chiller and/or the outer heat exchanger, where the outer heat exchanger is configured to enable heat exchange between the refrigerant and air outside the target temperature-controlled space; a second outlet branch, configured to connect the refrigerant outlet to the inner heat exchanger and/or the heat exchanger for the target temperature-controlled device, where the inner heat exchanger is configured to enable heat exchange between the refrigerant and air in the target temperature-controlled space, and the heat exchanger for the target temperature-controlled device is configured to enable heat exchange between the refrigerant and the heat exchange working medium for adjusting the temperature of the target temperature-controlled device; a first inlet branch, configured to connect the refrigerant inlet to the inner heat exchanger and/or the heat exchanger for the target temperature-controlled device; and a second inlet branch, configured to connect the refrigerant inlet to the low pressure chiller and/or the outer heat exchanger. The first outlet branch, the second outlet branch, the first inlet branch, and the second inlet branch respectively have a first stop valve, a second stop valve, a third stop valve, and a fourth stop valve for controlling opening and closing of the branch. The first stop valve, the second stop valve, the third stop valve, and the fourth stop valve may be integrated. 
     With the foregoing structure, the branches are controlled by the stop valves. This can reduce costs compared with a manner of using a three-way valve or the like. In addition, functions of the four stop valves are integrated into one integrated valve. This reduces a quantity of external pipelines connected between the valves, and the plurality of valves share a controller, thereby reducing manufacturing costs. 
     In an embodiment of the first aspect of this application, the thermal management system further includes a heat exchange circulation loop for the target temperature-controlled device. The heat exchange circulation loop for the target temperature-controlled device and the refrigerant loop jointly include the heat exchanger for the target temperature-controlled device. The heat exchanger for the target temperature-controlled device is configured to enable heat exchange between the refrigerant and a heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. 
     In an embodiment of the first aspect of this application, the motor coolant is the same as the heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. The motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device jointly include a 4-way valve. The 4-way valve is configured to switch the motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device between a series connection state and a mutual independence state. 
     With the foregoing structure, the motor coolant loop may be connected in series to the heat exchange circulation loop for the target temperature-controlled device. Therefore, for example, when the motor has a relatively large amount of residual heat, the target temperature-controlled device may be heated directly by the motor coolant, without running a heat pump unit, thereby reducing energy consumption. 
     In an embodiment of the first aspect of this application, the motor coolant loop includes a radiator, and the radiator is configured to dissipate heat from the motor coolant to the air outside the target temperature-controlled space. 
     With the foregoing structure, for example, when the temperature of the target temperature-controlled device is relatively high and the ambient temperature is relatively low, the heat exchange circulation loop for the target temperature-controlled device and the motor coolant loop may be connected in series and connected to the radiator, to cool the target temperature-controlled device and the motor by using the radiator. In addition, because the radiator in the motor coolant loop can be shared by the heat exchange circulation loop for the target temperature-controlled device, manufacturing costs can be reduced compared with a case in which radiators are separately disposed in the two loops. 
     In an embodiment of the first aspect of this application, the thermal management system is applied to an electric vehicle, the target temperature-controlled space is a passenger compartment, and the target temperature-controlled device is a battery. 
     In addition, to achieve the foregoing objective, a second aspect of this application provides an electric vehicle. The electric vehicle includes the thermal management system of any one of the structures in the first aspect. 
     In addition, to achieve the foregoing objective, a third aspect of this application provides a method for controlling a thermal management system. The thermal management system includes a refrigerant loop and a motor coolant loop. The refrigerant loop and the motor coolant loop jointly include a low pressure chiller. The low pressure chiller is configured to enable a refrigerant in the refrigerant loop to absorb heat from a motor coolant in the motor coolant loop through evaporation, to heat a target temperature-controlled device. When a temperature of the target temperature-controlled device is less than a first preset value, the target temperature-controlled device is heated by the heat absorbed by the refrigerant from the motor coolant through evaporation. 
     With the foregoing method, when the temperature of the target temperature-controlled device is less than the first preset value, in the low pressure chiller, the refrigerant in the refrigerant loop is enabled to absorb the heat from the motor coolant through evaporation, that is, the heat from the motor coolant is absorbed by a heat pump to heat the target temperature-controlled device. Therefore, the target temperature-controlled device can reach a required heating temperature even if a temperature of the motor coolant is relatively low, that is, the temperature of the motor coolant may be relatively low on a basis that a required heating effect can be achieved, so that a difference between the temperature of the motor coolant and an ambient temperature is relatively small. In this way, heat loss caused by dissipation of heat from a motor to a surrounding environment can be reduced, thereby improving utilization of the heat from the motor. 
     In an embodiment of the third aspect, the thermal management system further includes a heat exchange circulation loop for the target temperature-controlled device. The heat exchange circulation loop for the target temperature-controlled device and the refrigerant loop jointly include a heat exchanger for the target temperature-controlled device. The heat exchanger for the target temperature-controlled device is configured to enable heat exchange between the refrigerant and a heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. The motor coolant is the same as the heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. The motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device jointly include a 4-way valve. The 4-way valve is configured to switch the motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device between a series connection state and a mutual independence state. When a difference between a motor outlet coolant temperature and the temperature of the target temperature-controlled device is greater than a first preset difference, the 4-way valve is controlled to connect the motor coolant loop in series to the heat exchange circulation loop for the target temperature-controlled device, so that the target temperature-controlled device is heated by heat from the motor coolant. The motor outlet coolant temperature is a temperature of the motor coolant when the motor coolant flows out of the motor side. 
     In this way, when the difference between the motor outlet coolant temperature and the temperature of the target temperature-controlled device is greater than the first preset difference, that is, the motor outlet coolant temperature is much higher than the temperature of the target temperature-controlled device, for example, the motor has a relatively large amount of residual heat, a relatively good heating effect can be achieved by directly heating the target temperature-controlled device by using the motor coolant, without using the refrigerant as an intermediate heat exchange working medium, and without starting the refrigerant loop, thereby reducing energy consumption. 
     In an embodiment of the third aspect, the thermal management system further includes a heat exchange circulation loop for the target temperature-controlled device. The heat exchange circulation loop for the target temperature-controlled device and the refrigerant loop jointly include a heat exchanger for the target temperature-controlled device. The heat exchanger for the target temperature-controlled device is configured to enable heat exchange between the refrigerant and a heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. The motor coolant is the same as the heat exchange working medium in the heat exchange circulation loop for the target temperature-controlled device. The motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device jointly include a 4-way valve. The 4-way valve is configured to switch the motor coolant loop and the heat exchange circulation loop for the target temperature-controlled device between a series connection state and a mutual independence state. The motor coolant loop includes a radiator, and the radiator is configured to dissipate the heat from the motor coolant to ambient air. When a difference between the temperature of the target temperature-controlled device and an ambient temperature is greater than a second preset difference, the 4-way valve is controlled to connect the motor coolant loop in series to the heat exchange circulation loop for the target temperature-controlled device, so that the motor coolant absorbs heat from the target temperature-controlled device to cool the target temperature-controlled device, and the heat absorbed by the motor coolant is dissipated to the ambient air in the radiator. 
     In this way, when the difference between the temperature of the target temperature-controlled device and the ambient temperature is greater than the second preset difference, that is, the temperature of the target temperature-controlled device is much higher than the ambient temperature, the motor coolant absorbs the heat from the target temperature-controlled device, and dissipates the absorbed heat to the ambient air in the radiator, so that the target temperature-controlled device can be well cooled without running the refrigerant loop, thereby reducing energy consumption. 
     In addition, in the third aspect, another structure illustrated in the descriptions of the first aspect may be alternatively used. 
     Content of these aspects of this application is more clearly described in the following specific implementations. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of an architecture of a thermal management system in which a motor and a controller are directly used for active heating according to a comparative example for comparison with an embodiment of this application; 
         FIG. 2  is a schematic diagram of a structure of a heat exchange circulation loop system of a thermal management system according to an embodiment of this application; 
         FIG. 3  is a schematic block diagram of a structure of the foregoing thermal management system; 
         FIG. 4  is a diagram depicting an operating principle of the foregoing thermal management system in a heat pump heating mode; 
         FIG. 5  is a diagram depicting an operating principle of the foregoing thermal management system in a cooling mode; 
         FIG. 6  is a diagram depicting an operating principle of the foregoing thermal management system in a battery passive cooling mode; 
         FIG. 7  is a diagram depicting an operating principle of the foregoing thermal management system in a battery passive heating mode; 
         FIG. 8  is a diagram depicting an operating principle of the foregoing thermal management system in an air conditioning defrost mode; 
         FIG. 9  is a diagram depicting an operating principle of the foregoing thermal management system in a battery no thermal management mode; 
         FIG. 10  is a schematic diagram of a structure of a heat exchange circulation loop system of a thermal management system according to a variation example of this application; 
         FIG. 11  is a schematic diagram of a structure of a heat exchange circulation loop system of a thermal management system according to another variation example of this application; and 
         FIG. 12  is a diagram depicting control logic of thermal management for a battery. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following descriptions, a “connection” mentioned is usually a connection by using a pipeline, unless otherwise specified. 
     In addition, in the following descriptions, descriptions such as “first” and “second” are used, and are merely intended to distinguish between similar objects, but not to limit a sequence or importance. 
     For ease of understanding, some related comparative examples are described before the embodiments of this application are described. 
     For example, in winter, because an ambient temperature is relatively low, a temperature of a battery cell of an electric vehicle is also relatively low. This causes problems such as a limitation on battery charging and discharging functions and a battery capacity attenuation. Therefore, a thermal management system of the electric vehicle is usually equipped with a Positive Temperature Coefficient (PTC) heater (positive temperature coefficient thermistor heater, PTC heater or PTC for short) or High Voltage Heater (HVH) to heat the battery and keep the temperature of the battery cell above 0° C., so as to ensure that the battery operates at a relatively appropriate temperature. 
     In addition, in addition to a heating requirement of the battery, a passenger compartment of the electric vehicle also requires heating (that is, air conditioning heating) in winter. There are mainly two manners of air conditioning heating: (1) Heating is performed by using an air conditioning PTC. In an embodiment, direct heating by using an air-side PTC and indirect heating by using a water-side PTC are included. (2) A compressor of a heat pump system absorbs heat from an environment and then releases heat into the passenger compartment. However, an R134a refrigerant heat pump is used currently. Due to characteristics of a refrigerant, below −10° C., it can be hardly ensured that a heat requirement of the passenger compartment can be met only by absorbing heat from the environment. Therefore, most vehicles with a heat pump system are still equipped with an air conditioning PTC, mainly to ensure proper heating of a passenger compartment in an environment below −10° C. 
     To sum up, regardless of battery heating or air conditioning heating and regardless of whether a heat pump system is used, currently, an electric vehicle still mainly relies on a PTC. Currently, the PTC is sold on the market at a relatively high price, resulting in relatively high costs of a thermal management system using the PTC. In addition, for example, in China, climate and ambient temperatures in different regions vary greatly. In South China, the temperature is above 0° C. throughout a year, and a battery heating requirement is relatively low. In addition, in some regions, even if the temperature is below 0° C. in winter, a proportion of this time in a year is quite small. Therefore, if an entire series of a vehicle model is equipped with PTCs, utilization decreases in a further south region. 
     To resolve the foregoing problem, currently, some manufacturers tend to generate heat through stalling or low-efficiency operating of oil-cooled motors, to gradually replace PTCs. However, thermal efficiency of heating through stalling of a motor is the key to determining whether this technology can be applied. In an embodiment, heat generated by a motor and a motor control unit (MCU) cannot be 100% supplied to a coolant. A part of the heat is dissipated to an environment through motor and gear box housings. Only a part of the heat that is transferred to the coolant through oil in a heat exchanger can be actually used to heat a battery or a passenger compartment. In particular, in winter, a larger difference between an oil temperature of the motor and an ambient temperature results in greater heat loss caused by heat dissipation to the environment through the motor and gear box housings, and therefore results in lower thermal efficiency. Usually, when the battery and the passenger compartment are heated by cooling water of the motor, a water temperature required for heating the battery is 20° C. or above, and a water temperature required for air conditioning heating is 60° C. or above. To achieve these temperatures, a temperature of the motor needs to be higher. As a result, a large part of heat generated by the motor is dissipated to the environment, causing very low utilization of the heat generated by the motor. 
       FIG. 1  is a schematic diagram of an architecture of a thermal management system for an electric vehicle in which a motor and a controller are directly used for active heating according to a comparative example. As shown in  FIG. 1 , the thermal management system  200  includes a compressor  11 , an evaporator  213   a , and a condenser  151 A. These devices are connected in series through a refrigerant pipeline to constitute a refrigerant loop. In addition, the evaporator  213   a , a fan  133 , and an air conditioning PTC  213   b  constitute an HVAC box (Heating Ventilation and Air Conditioning Box, heating ventilation and air conditioning box, also referred to as an air conditioning box)  213 . The evaporator  213   a  is used for cooling in a passenger compartment, and the air conditioning PTC  213   b  is used for heating in the passenger compartment. 
     In addition, the refrigerant loop further includes a battery heat exchanger  14  connected in parallel to the evaporator  213   a . The battery heat exchanger  14  further belongs to a battery heat exchange circulation loop. The battery heat exchange circulation loop includes a battery  31  (to be precise, a temperature regulating water path in the battery  31 ), a drive pump  32 , and the battery heat exchanger  14  that are connected in series through a water pipe. 
     In addition, the thermal management system  200  further includes a motor  51  and a motor control unit  52  (the motor  51  and the motor control unit  52  each include a cooling water path), a drive pump  53 , a radiator  152 , and a three-way valve  74 . These devices are connected in series through a water pipe to constitute a motor cooling water path. The radiator  152  and the condenser  151 A share a fan  153 , and the three devices are assembled and disposed near a front grille of the vehicle to constitute a front module  15 . 
     A four-way valve  33  is disposed between the battery heat exchange circulation loop and the motor cooling water path. A state of the four-way valve  33  can be switched so that the two water paths can switch between a series connection state and a mutual independence state. 
     Usually, when heat needs to be dissipated for the motor  51 , the drive pump  53  enables water serving as a motor coolant to circulate in the motor cooling water path, so that water flowing through the motor  51  and the motor control unit  52  cools the motor  51  and the motor control unit  52  and is heated. Under control of the three-way valve  74 , the heated water may flow to the radiator  152 , and heat of the water is dissipated through the radiator  152  to air outside the passenger compartment. 
     In addition, for example, when an ambient temperature is relatively low in winter, the battery needs to be heated upon initial startup of the vehicle. In this case, the motor  51  is enabled to stall or operate at low efficiency, and the four-way valve  33  is switched so that the battery heat exchange circulation loop is connected in series to the motor cooling water path. In this way, water heated by the motor  51  and the motor control unit  52  flows to the battery  31 , so that the battery  31  can be heated. 
     With this technology of heating the battery  31  through active heating by the motor  51  and the motor control unit  52 , a battery body usually needs to be heated to a temperature of 0° C. or above, and a motor cooler outlet water temperature needs to be 10° C. or above. The following table compares heating efficiency of the motor  51  and the motor control unit  52  at an ambient temperature of −10° C. and a flow rate of 10 L/min when an MCU inlet water temperature is controlled to be 10° C. and 20° C. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Comparison of thermal efficiency of the motor and the MCU at inlet  
               
               
                 water temperatures of 10° C. and 20° C.  
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Heat  
                 Heat released  
                 Total  
               
               
                   
                   
                 absorbed  
                 by the motor  
                 thermal  
               
               
                   
                   
                 by a  
                 and the  
                 efficiency/  
               
               
                 No.  
                 Test name  
                 coolant/kW  
                 MCU/kW  
                 % 
               
               
                   
               
               
                 1  
                 Inlet water temperature  
                 3.9  
                 4.8  
                 81.1%  
               
               
                   
                 of 10° C., with the motor  
                   
                   
                   
               
               
                   
                 stalling  
                   
                   
                   
               
               
                 2  
                 Inlet water temperature  
                 3.6  
                 4.5  
                 81.2%  
               
               
                   
                 of 10° C., with the motor  
                   
                   
                   
               
               
                   
                 operating at 2000 rpm  
                   
                   
                   
               
               
                   
                 and an efficiency of 54%  
                   
                   
                   
               
               
                 3  
                 Inlet water temperature  
                 3.3  
                 4.9  
                 67.3%  
               
               
                   
                 of 20° C., with the motor  
                   
                   
                   
               
               
                   
                 stalling  
                   
                   
                   
               
               
                 4  
                 Inlet water temperature  
                 3.0  
                 4.6  
                 64.9%  
               
               
                   
                 of 20° C., with the motor  
                   
                   
                   
               
               
                   
                 operating at 2000 rpm  
                   
                   
                   
               
               
                   
                 and an efficiency of 54% 
               
               
                   
               
            
           
         
       
     
     The result in the foregoing table shows that a higher motor inlet water temperature results in lower thermal efficiency, and thermal efficiency at an inlet water temperature of 20° C. is at least 10% lower than that at an inlet water temperature of 10° C. Because motor and gear box housings dissipate heat to a low-temperature environment, a higher overall temperature of the motor results in a larger proportion of heat dissipated to the environment and a smaller proportion of heat supplied to the coolant. Therefore, from a perspective of fully utilizing heat generated through active heating by the motor, it is inappropriate to use the heat from the motor directly as a high-temperature heat source. For example, hot water at 60° C. is required for air conditioning heating. If hot water is heated to 60° C. through active heating by the motor, thermal efficiency is very low. 
     Therefore, the embodiments of this application provide a thermal management system capable of improving utilization of heat generated by a motor, and an electric vehicle with the system. 
     The following describes an embodiment of this application with reference to  FIG. 2  to  FIG. 9 . 
     This embodiment relates to a thermal management system  100 , a method for controlling the thermal management system  100 , and an electric vehicle (not shown in the figure) including the thermal management system  100 . Regarding the electric vehicle, this embodiment is particularly applicable to a battery electric vehicle, and is also applicable to a hybrid vehicle. In addition to the thermal management system  100 , typically, the electric vehicle further includes a battery  31 , a motor  51 , and a motor control unit  52 . The battery  31  is configured to supply electric power to the motor  51  and a compressor  11 , drive pumps  32  and  53 , fans  133  and  153 , and the like that are described below. The motor  51  is configured to drive a wheel (not shown in the figure) of the electric vehicle by using a gear box (not shown in the figure) and the like, to provide a driving force for running of the electric vehicle. The motor control unit  52  is configured to control the motor  51 . 
       FIG. 2  is a schematic diagram of a structure of a heat exchange circulation loop system of the thermal management system in this embodiment.  FIG. 3  is a schematic block diagram of a structure of the foregoing thermal management system. 
     As shown in  FIG. 3 , the thermal management system  100  has a control unit  110  and a heat exchange circulation loop system  120 . Typically, the control unit  110  may be an ECU (Electronic Control Unit, electronic control unit), and is configured to control devices and components in the heat exchange circulation loop system  120  that are described below, so that the heat exchange circulation loop system  120  operates based on modes described in detail below. Refer to  FIG. 2  and  FIG. 3 , the heat exchange circulation loop system  120  includes a refrigerant loop  10 , a battery heat exchange circulation loop  30 , and a motor coolant loop  50 . 
     The refrigerant loop  10  is described below. As shown in  FIG. 2 , the refrigerant loop  10  includes the compressor  11 , a gas-liquid separator  12 , inner heat exchangers  131  and  132 , a battery heat exchanger  14 , an outer heat exchanger  151 , and a low pressure chiller  16 . These devices are connected through a refrigerant pipeline. 
     The compressor  11  is a driving source that enables a refrigerant (which may be, for example, a phase-change refrigerant such as R134a) to flow in the refrigerant loop  10 , and has a refrigerant outlet  11   a  and a refrigerant inlet  11   b.    
     The gas-liquid separator  12  is connected to the refrigerant inlet  11   b  side of the compressor  11  to separate a vapor-phase refrigerant from a liquid-phase refrigerant and prevent the liquid-phase refrigerant from entering the compressor  11 . 
     The inner heat exchangers  131  and  132  are configured to exchange heat with air in a passenger compartment (not shown in the figure) of the electric vehicle, so as to heat or cool the air in the passenger compartment, and implement the so-called air conditioning function. In addition, the inner heat exchangers  131  and  132  are assembled with the fan  133  to constitute an air conditioning box  13 . In this embodiment, the two inner heat exchangers  131  and  132  are disposed, and are connected in series through the refrigerant pipeline. 
     The battery heat exchanger  14  is shared by the refrigerant loop  10  and the battery heat exchange circulation loop  30 , is connected to both a heat pump refrigerant pipeline and a battery circulation water path, and is configured to enable a refrigerant in the refrigerant loop  10  to heat or cool a heat exchange working medium in the battery heat exchange circulation loop  30  (in this embodiment, a mixture obtained by mixing water and ethylene glycol based on a specific proportion serves as the heat exchange working medium), so that a temperature of the battery  31  can be adjusted by using the heated or cooled heat exchange working medium. 
     The outer heat exchanger  151  is configured to enable heat exchange between the refrigerant in the refrigerant loop  10  and air outside the passenger compartment, including enabling the refrigerant to absorb heat from the external air and dissipate heat to the external air. In addition, in this embodiment, the outer heat exchanger  151  and a radiator  152  described below share the fan  153 , and the three devices are usually disposed near a front grille of the electric vehicle to constitute a front module  15 . 
     The low pressure chiller  16  is shared by the refrigerant loop  10  and the motor coolant loop  50 , is connected to both the heat pump refrigerant pipeline and a motor coolant pipeline, and is configured to enable the refrigerant in the refrigerant loop  10  to absorb heat from a motor coolant in the motor coolant loop  50  through evaporation. 
     As described above, the compressor  11 , the gas-liquid separator  12 , the inner heat exchangers  131  and  132 , the battery heat exchanger  14 , the outer heat exchanger  151 , and the low pressure chiller  16  are connected through the heat pump refrigerant pipeline. A specific connection structure of these devices is described below. 
     In an embodiment, the inner heat exchangers  131  and  132  are connected in parallel to the battery heat exchanger  14 , where a branch in which the inner heat exchangers  131  and  132  are located is referred to as an inner heat exchanger branch  113 , and a branch in which the battery heat exchanger  14  is located is referred to as a battery heat exchanger branch  114 ; the outer heat exchanger  151  is connected in parallel to the low pressure chiller  16 , where a branch in which the outer heat exchanger  151  is located is referred to as an outer heat exchanger branch  115 , and a branch in which the low pressure chiller  16  is located is referred to as a low pressure chiller branch  116 ; and the compressor  11 , the inner heat exchangers  131  and  132  and the battery heat exchanger  14  that are connected in parallel, and the outer heat exchanger  151  and the low pressure chiller  16  that are connected in parallel are connected in series. 
     In this embodiment, the refrigerant outlet  11   a  of the compressor  11  is connected, through a first outlet branch  111   a , to the outer heat exchanger  151  and the low pressure chiller  16  that are connected in parallel; and is connected, through a second outlet branch  111   b , to the inner heat exchangers  131  and  132  and the battery heat exchanger  14  that are connected in parallel. The first outlet branch  111   a  and the second outlet branch  111   b  share a three-way valve  71 . A state of the three-way valve  71  is switched so that the first outlet branch  111   a  and the second outlet branch  111   b  alternately switch between an open state and a closed state. 
     In an embodiment, the three-way valve  71  has three interfaces:  71   a ,  71   b , and  71   c . The interface  71   b  is connected to the refrigerant outlet  11   a  of the compressor  11 . The interface  71   a  is connected to the outer heat exchanger  151  and the low pressure chiller  16 . The interface  71   c  is connected to the inner heat exchangers  131  and  132  and the battery heat exchanger  14 . When the three-way valve  71  is switched to a state in which the interface  71   b  is connected to the interface  71   a , the first outlet branch  111   a  is open, and the second outlet branch  111   b  is closed. When the three-way valve  71  is switched to a state in which the interface  71   b  is connected to the interface  71   c , the first outlet branch  111   a  is closed, and the second outlet branch  111   b  is open. 
     In addition, the refrigerant inlet  11   b  of the compressor  11  is connected, through a first inlet branch  112   a , to the inner heat exchangers  131  and  132  and the battery heat exchanger  14  that are connected in parallel; and is connected, through a second inlet branch  112   b , to the outer heat exchanger  151  and the low pressure chiller  16  that are connected in parallel. The first inlet branch  112   a  and the second inlet branch  112   b  share a three-way valve  72 . A state of the three-way valve  72  is switched so that the first inlet branch  112   a  and the second inlet branch  112   b  alternately switch between an open state and a closed state. In an embodiment, the three-way valve  72  has three interfaces:  72   a ,  72   b , and  72   c . The interface  72   a  is connected (through the gas-liquid separator  12 ) to the refrigerant inlet  11   b  of the compressor  11 . The interface  72   b  is connected to the outer heat exchanger  151  and the low pressure chiller  16 . The interface  72   c  is connected to the inner heat exchangers  131  and  132  and the battery heat exchanger  14 . When the three-way valve  72  is switched to a state in which the interface  72   a  is connected to the interface  72   c , the first inlet branch  112   a  is open, and the second inlet branch  112   b  is closed. When the three-way valve  72  is switched to a state in which the interface  72   a  is connected to the interface  72   b , the first inlet branch  112   a  is closed, and the second inlet branch  112   b  is open. 
     In addition, in the inner heat exchanger branch  113 , a location of the inner heat exchanger  131  is closer to the compressor  11  than that of the inner heat exchanger  132 , and an electronic expansion valve  61  is disposed between the inner heat exchanger  131  and the inner heat exchanger  132 . The electronic expansion valve  61  is a valve with an adjustable opening degree and can function as a switching valve and a throttle valve. Further, in the inner heat exchanger branch  113 , an electronic expansion valve  62  is disposed on a side, of the inner heat exchanger  132 , that is away from the inner heat exchanger  131 , and a refrigerant temperature and pressure sensor  81  is disposed on a side, of the inner heat exchanger  131 , that is close to the compressor  11 . 
     In addition, an electronic expansion valve  63  connected in series to the battery heat exchanger  14  is disposed in the battery heat exchanger branch  114 . In this embodiment, the electronic expansion valve  63  is disposed on a side, of the battery heat exchanger  14 , that is away from the compressor  11 . The electronic expansion valve  63  is a valve with an adjustable opening degree and can function as a switching valve and a throttle valve. In addition, a refrigerant temperature and pressure sensor  82  is disposed on a side, of the battery heat exchanger  14 , that is close to the compressor  11 . 
     In addition, the inner heat exchangers  131  and  132  and the battery heat exchanger  14  that are connected in parallel are connected, through a three-way valve  73 , to one of the outer heat exchanger  151  and the low pressure chiller  16  that are connected in parallel. In an embodiment, the three-way valve  73  has three interfaces:  73   a ,  73   b , and  73   c . The interface  73   a  is connected to the low pressure chiller  16 . The interface  73   b  is connected to the outer heat exchanger  151 . The interface  73   c  is connected to the inner heat exchangers  131  and  132  and the battery heat exchanger  14  that are connected in parallel. 
     In this embodiment, the three-way valve  73  is a three-way valve capable of adjusting opening degrees of the interfaces  73   a  and  73   b . By adjusting the opening degrees of the interfaces  73   a  and  73   b  (the opening degrees may be 0), a refrigerant flow rate of each of the outer heat exchanger  151  and the low pressure chiller  16  can be adjusted, and a refrigerant flow ratio between the outer heat exchanger  151  and the low pressure chiller  16  can be adjusted. Further, a heat supply amount shared by the outer heat exchanger  151  and the low pressure chiller  16  can be adjusted, as described below. The three-way valve  73  is an example of a 3-way valve for adjusting the refrigerant flow ratio between the outer heat exchanger  151  and the low pressure chiller  16  in this application. 
     In addition, in the low pressure chiller branch  116 , a refrigerant temperature and pressure sensor  83  is disposed on a side, of the low pressure chiller  16 , that is close to the compressor  11 . In the outer heat exchanger branch  115 , a refrigerant temperature and pressure sensor  84  is disposed on a side, of the outer heat exchanger  151 , that is close to the compressor  11 . The refrigerant temperature and pressure sensors  83  and  84  are configured to detect a temperature and pressure of the refrigerant. 
     A structure of the battery heat exchange circulation loop  30  is described below. The battery heat exchange circulation loop  30  corresponds to a heat exchange circulation loop for a target temperature-controlled device in this application. 
     As shown in  FIG. 2 , the battery heat exchange circulation loop  30  includes the battery  31  (e.g., an inner heat exchange water path of the battery  31 ), the drive pump  32 , and the battery heat exchanger  14  that are connected in series. The battery  31  is configured to supply electric power to the motor  51 , the compressor  11 , the drive pumps  32  and  53 , the fans  133  and  153 , and the like. The drive pump  32  is a driving source that enables the heat exchange working medium to flow in the battery heat exchange circulation loop  30 . As described above, the battery heat exchanger  14  is configured to enable heat exchange between the heat exchange working medium in the battery heat exchange circulation loop  30  and the refrigerant in the refrigerant loop  10 . Driven by the drive pump  32 , the heat exchange working medium flows through the battery heat exchanger  14 , and absorbs heat from the refrigerant in the refrigerant loop  10  or dissipates heat to the refrigerant in the refrigerant loop  10 , so that the heat exchange working medium is heated or cooled and can further heat or cool the battery  31 . 
     In addition, in the battery heat exchange circulation loop  30 , temperature sensors  91  and  92  are respectively disposed on two sides of the battery  31 , and the temperature sensors  91  and  92  are configured to measure an outlet water temperature and an inlet water temperature of the battery  31 . 
     In addition, a four-way valve  33  is further disposed in the battery heat exchange circulation loop  30 . The four-way valve  33  is shared by the battery heat exchange circulation loop  30  and the motor coolant loop  50 . As described in detail below, the four-way valve  33  is configured to switch the battery heat exchange circulation loop  30  and the motor coolant loop  50  between a series connection state and a mutual independence state. 
     The motor coolant loop  50  is described below. 
     As shown in  FIG. 2 , the motor coolant loop  50  includes the motor  51 , the motor control unit  52 , the radiator  152 , the low pressure chiller  16 , and the drive pump  53 . As described above, the motor  51  is configured to drive a wheel (not shown in the figure) of the electric vehicle by using a gear box (not shown in the figure) and the like, to provide a driving force for running of the electric vehicle. The motor control unit  52  is configured to control the motor  51 . The drive pump  53  is a driving source for driving the motor coolant to flow in the motor coolant loop  50 . The radiator  152  is configured to enable heat exchange between the motor coolant and air outside the passenger compartment, to dissipate heat from the motor coolant to the air outside the passenger compartment. The low pressure chiller  16  is configured to enable heat exchange between the motor coolant and the refrigerant in the refrigerant loop  10 , to transfer heat from the motor coolant to the refrigerant in the refrigerant loop  10 . In other words, the low pressure chiller  16  is configured to enable the refrigerant in the refrigerant loop  10  to absorb the heat from the motor coolant. In addition, the air outside the passenger compartment herein corresponds to ambient air in this application. 
     In the motor coolant loop  50 , the radiator  152  is connected in parallel to the low pressure chiller  16 , and the two devices are connected to the motor  51  through a three-way valve  74 . In an embodiment, the three-way valve  74  has interfaces  74   a ,  74   b , and  74   c . The interface  74   a  is connected to the motor  51 . The interface  74   b  is connected to the radiator  152 . The interface  74   c  is connected to the low pressure chiller  16 . When the three-way valve  74  is switched to a state in which the interface  74   a  is connected to the interface  74   b , the radiator  152  (a branch in which the radiator  152  is located) is open, and the low pressure chiller  16  (a branch in which the low pressure chiller  16  is located) is closed. When the three-way valve  74  is switched to a state in which the interface  74   a  is connected to the interface  74   c , the radiator  152  is closed, and the low pressure chiller  16  is open. 
     In addition, as described above, the motor coolant loop  50  and the battery heat exchange circulation loop  30  jointly have the four-way valve  33 , and the motor coolant loop  50  and the battery heat exchange circulation loop  30  can be switched between the series connection state and the mutual independence state by using the four-way valve  33 . In an embodiment, the four-way valve  33  has interfaces  33   a ,  33   b ,  33   c , and  33   d . The interfaces  33   b  and  33   c  are connected to pipelines on a side of the battery heat exchange circulation loop  30 , and in this embodiment, are respectively connected to the drive pump  32  and the battery  31  through the pipelines. The interfaces  33   a  and  33   d  are connected to pipelines on a side of the motor coolant loop  50 , and in this embodiment, are respectively connected to one of the motor  51  and the motor control unit  52 , and one of the radiator  152  and the low pressure chiller  16  through the pipelines. When the four-way valve  33  is switched to a state in which the interfaces  33   a  and  33   d  are connected and the interfaces  33   b  and  33   c  are connected, the motor coolant loop  50  and the battery heat exchange circulation loop  30  are independent of each other. When the four-way valve  33  is switched to a state in which the interface  33   a  is connected to the interface  33   b  and the interface  33   c  is connected to the interface  33   d , the motor coolant loop  50  is connected in series to the battery heat exchange circulation loop  30 . 
     In addition, in this embodiment, the motor coolant in the motor coolant loop  50  is the same as the heat exchange working medium in the battery heat exchange circulation loop  30 . Therefore, it is possible to connect the motor coolant loop  50  and the battery heat exchange circulation loop  30  in series. 
     In addition, in this embodiment, the temperature sensors  93  and  94  are respectively disposed on two sides of the motor  51  and the motor control unit  52  as a whole in the motor coolant loop  50 , and are configured to detect the motor outlet water temperature and the motor inlet water temperature. 
     The thermal management system  100  in this embodiment basically has the foregoing circulation loop structure. With this structure, under control of the control unit  110 , a heat pump heating mode, a cooling mode, a battery passive cooling mode, a battery passive heating mode, an air conditioning defrost and dehumidification mode, and a battery no thermal management mode can be implemented. These modes are described below with reference to  FIG. 4  to  FIG. 9 , including descriptions of a control method for enabling the thermal management system  100  to implement these modes and descriptions of states of the heat exchange circulation loop system  120  of the thermal management system  100  in these modes. 
       FIG. 4  is a diagram depicting an operating principle of the foregoing thermal management system in a heat pump heating mode.  FIG. 5  is a diagram depicting an operating principle of the foregoing thermal management system in a cooling mode.  FIG. 6  is a diagram depicting an operating principle of the foregoing thermal management system in a battery passive cooling mode.  FIG. 7  is a diagram depicting an operating principle of the foregoing thermal management system in a battery passive heating mode.  FIG. 8  is a diagram depicting an operating principle of the foregoing thermal management system in an air conditioning defrost mode.  FIG. 9  is a diagram depicting an operating principle of the foregoing thermal management system in a battery no thermal management mode. 
     In addition, in  FIG. 4  to  FIG. 9 , for ease of understanding, a flow path in a closed state in the heat exchange circulation loop system  120  in each mode is represented by a dashed line, and a flow path in a high-temperature state in the refrigerant loop  10  is represented by a bold solid line. 
     &lt;Heat Pump Heating Mode&gt; 
     The heat pump heating mode includes three sub-modes: a battery heating mode, an air conditioning heating mode, and a battery and air conditioning heating mode. 
     First, the battery and air conditioning heating mode is described. In this mode, as shown in  FIG. 4 , the refrigerant loop  10  operates, and the battery heat exchange circulation loop  30  and the motor coolant loop  50  each operate independently. 
     In this case, in the motor coolant loop  50 , the motor control unit  52  controls, according to an instruction sent by the control unit  110  directly or indirectly by using a vehicle control unit (not shown in the figure), the motor  51  to stall or operate at low efficiency. In addition, under control of the control unit  110 , the three-way valve  74  is switched to a state in which the interface  74   a  is connected to the interface  74   c , the branch in which the low pressure chiller  16  is located is open, and the branch in which the radiator  152  is located is closed. In this state, the drive pump  53  drives the motor coolant to flow, and the motor coolant is heated by cooling the motor  51  and the motor control unit  52 . As described below, in the low pressure chiller  16 , the heated motor coolant transfers heat to the refrigerant in the refrigerant loop  10 . 
     In the refrigerant loop  10 , under control of the control unit  110 , the three-way valve  71  is switched to a state in which the interface  71   b  is connected to the interface  71   c , the three-way valve  72  is switched to a state in which the interface  72   a  is connected to the interface  72   b , the electronic expansion valve  61  is switched to a fully open state, the electronic expansion valve  62  is switched to a throttling state, and the electronic expansion valve  63  is switched to a fully open state. 
     In this way, in the refrigerant loop  10 , a high-temperature and high-pressure refrigerant flowing out of the refrigerant outlet  11   a  of the compressor  11  flows into the inner heat exchangers  131  and  132 , and exchanges, in the inner heat exchangers  131  and  132 , heat with air in the passenger compartment to release heat to the air in the passenger compartment, so that the passenger compartment can be heated; and another high-temperature and high-pressure refrigerant enters the battery heat exchanger  14 , and exchanges, in the battery heat exchanger  14 , heat with the heat exchange working medium in the battery heat exchange circulation loop  30  to release heat to the heat exchange working medium in the battery heat exchange circulation loop  30 , so that the battery is heated by the heated heat exchange working medium. 
     A high-temperature refrigerant flowing out of the inner heat exchanger  131  is throttled by the electronic expansion valve  62  into vapor and liquid phases. A refrigerant flowing out of the battery heat exchanger  14  is throttled by the electronic expansion valve  63  into vapor and liquid phases. The two refrigerants are combined and then distributed by the three-way valve  73  into two refrigerants. One refrigerant passes through the interface  73   a  of the three-way valve  73 , enters the low pressure chiller  16 , and evaporates in the low pressure chiller  16  into a vapor-phase refrigerant to absorb heat from the motor coolant. The other refrigerant passes through the interface  73   b , enters the outer heat exchanger  151 , and evaporates in the outer heat exchanger  151  to absorb heat from the air outside the passenger compartment. Then the two refrigerants return to the compressor through the refrigerant inlet  11   b  of the compressor  11  to complete a cycle. 
     As described above, in this embodiment, opening degrees of the interface  73   a  and the interface  73   b  of the three-way valve  73  are adjustable, so that refrigerant flow rates of the outer heat exchanger  151  and the low pressure chiller  16  can be distributed, to adjust a heat supply amount shared by the outer heat exchanger  151  and the low pressure chiller  16 . For example, a specific adjustment manner may be as follows: When an ambient temperature (an air temperature outside the passenger compartment) is higher than a preset temperature (for example, −10° C.), heat absorbed from an environment can meet a heating requirement. A refrigerant flow rate is adjusted by using the three-way valve  73 , so that most or all of refrigerants flow to the outer heat exchanger  151 . When all of the refrigerants flow to the outer heat exchanger  151 , the motor  51  can stop operating. When an ambient temperature is lower than a preset temperature (for example, −10° C.) and sufficient heat cannot be absorbed from an environment, or when a heat exchange function is degraded due to frosting of the outer heat exchanger  151  after long-term use, a refrigerant flow rate is adjusted by using the three-way valve  73 , so that most of refrigerants flow to the low pressure chiller  16 . 
     An implementation of the battery and air conditioning heating mode is described above. Based on the battery and air conditioning heating mode, the battery heating mode can be implemented by closing the electronic expansion valve  61  to close the inner heat exchanger branch  113 . In addition, based on the battery and air conditioning heating mode, the air conditioning heating mode can be implemented by closing the electronic expansion valve  63 . 
     In this embodiment, when heating is performed through active heating by the motor  51 , heat from the motor coolant is absorbed by the refrigerant in the refrigerant loop  10 . Then the refrigerant that has absorbed the heat releases the heat to the air in the passenger compartment or the heat exchange working medium in battery heat exchange circulation loop  30 . In other words, in this embodiment, the heat from the motor coolant is transferred by the refrigerant in the refrigerant loop  10  to a heated object (the battery  31  or the air in the passenger compartment). 
     It is well known that a principle of a heat pump is to transfer heat through heat absorption and heat release by a refrigerant in a process of switching between a vapor phase and a liquid phase. During heating, heat exchange can be effectively performed to heat a heated object to a required temperature, without requiring a heat source from which the refrigerant absorbs heat to have a very high temperature. Therefore, in this embodiment in which heat from the motor  51  is transferred by the refrigerant loop  10 , it is not necessarily required that the motor coolant serving as a heat source from which a refrigerant of a heat pump absorbs heat be heated by the motor  51  and the motor control unit  52  to a high temperature such as 20° C. or 60° C. in the foregoing descriptions. Usually, a corresponding heating requirement can be met by controlling the motor outlet water temperature to be, for example, within 10° C. In this way, a temperature difference between the motor  51  and the motor control unit  52  and an environment is reduced, heat loss caused by heat dissipation from the motor  51  and the motor control unit  52  to the environment is reduced, and utilization of heat from the motor is improved. 
     In addition, in this embodiment, refrigerant flow rates of the low pressure chiller  16  and the outer heat exchanger  151  are adjusted by using the three-way valve  73 , so that a heat supply amount shared by the low pressure chiller  16  and the outer heat exchanger  151  can be adjusted. For example, when an ambient temperature is relatively high, heat may be absorbed from an environment mainly by the outer heat exchanger  151  or only by the outer heat exchanger  151 , and a refrigerant flow rate of the low pressure chiller  16  is made to be relatively small or zero 3-way valve. That is, heat generated by the motor  51  is reduced, or the motor  51  is turned off, without supplying heat through stalling or low-efficiency operating of the motor, thereby suppressing use of a motor-based heating mode with relatively low heat conversion efficiency and reducing energy consumption. When an ambient temperature is relatively low, or when the outer heat exchanger is frosted after long-term use, a refrigerant flow rate of the low pressure chiller  16  may be increased by using the valve  73 , to increase a heat supply amount shared by the low pressure chiller  16  (in other words, a heating amount shared by the motor  51  and the motor control unit  52 ), thereby avoiding a failure to heat the battery  31  or the passenger compartment to a required temperature due to an insufficient heating amount. 
     &lt;Cooling Mode&gt; 
     The cooling mode includes three sub-modes: a battery cooling mode, an air conditioning cooling mode, and a battery and air conditioning cooling mode. 
     First, the battery and air conditioning cooling mode is described. As shown in  FIG. 5 , in the battery and air conditioning cooling mode, the refrigerant loop  10  operates, and the battery heat exchange circulation loop  30  and the motor coolant loop  50  each operate independently. 
     In the refrigerant loop  10 , a high-temperature and high-pressure refrigerant flowing out of the refrigerant outlet  11   a  of the compressor  11  enters the outer heat exchanger  151  through the interfaces  71   b  and  71   a  of the three-way valve  71 , releases heat to the air outside the passenger compartment in the outer heat exchanger  151 , and is divided into two refrigerants after passing through the interfaces  73   b  and  73   c  of the three-way valve  73 . One refrigerant is throttled into a liquid-phase refrigerant by the electronic expansion valve  62  in a throttling state. The liquid-phase refrigerant enters the inner heat exchangers  131  and  132 , and evaporates in the inner heat exchanger  131  and  132  to absorb heat from the air in the passenger compartment, so as to cool the passenger compartment. The other refrigerant is throttled into a liquid-phase refrigerant by the electronic expansion valve  63  in a throttling state. The liquid-phase refrigerant enters the battery heat exchanger  14 , and evaporates in the battery heat exchanger  14  to absorb heat from the heat exchange working medium in the battery heat exchange circulation loop  30 , so as to cool the heat exchange working medium in the battery heat exchange circulation loop  30 . 
     In the battery heat exchange circulation loop  30 , driven by the drive pump  32 , water cooled in the battery heat exchanger  14  enters the battery  31  to cool the battery  31 . 
     In addition, in the refrigerant loop  10 , the interface  73   a  of the three-way valve  73  is closed, so that the refrigerant does not flow through the low pressure chiller  16 . 
     In addition, in this embodiment, in the battery and air conditioning cooling mode, the three-way valve  74  in the motor coolant loop  50  is switched to a state in which the interface  74   a  is connected to the interface  74   b . Driven by the drive pump  53 , the motor coolant flows through the motor  51  and the motor control unit  52 , enters the radiator  152 , dissipates heat to the air outside the passenger compartment in the radiator  152 , and then flows back to the motor  51  and the motor control unit  52  through the drive pump  53  to complete a cycle. In addition, in the motor coolant loop  50 , the interface  74   a  and the interface  74   c  of the three-way valve  74  are not connected, and the motor coolant does not flow through the low pressure chiller  16 . 
     Based on the implementation of the battery and air conditioning cooling mode, the battery cooling mode can be implemented by closing the electronic expansion valve  62 , and the air conditioning cooling mode can be implemented by closing the electronic expansion valve  63 . 
     &lt;Battery Passive Cooling Mode&gt; 
     As shown in  FIG. 6 , when a battery temperature is relatively high and an ambient temperature is relatively low, the four-way valve  33  may be switched to connect the battery heat exchange circulation loop  30  and the motor coolant loop  50  in series, and connect them to the radiator  152 , to cool the battery  31  and the motor  51  by using the radiator  152 . In this case, the refrigerant loop  10  does not operate. 
     In this embodiment, the battery heat exchange circulation loop  30  is connected in series to the motor coolant loop  50  to dissipate heat by using the radiator  152  in the motor coolant loop  50 . Compared with a structure in which a radiator is disposed in each of the two loops, this can reduce manufacturing costs. 
     &lt;Battery Passive Heating Mode&gt; 
     As shown in  FIG. 7 , when a battery temperature is relatively low and the motor has a relatively large amount of residual heat, the four-way valve  33  may be switched to connect the motor coolant loop  50  and the battery heat exchange circulation loop  30  in series, and short-circuit the radiator  152 , to heat the battery  31  by using the residual heat from the motor. In this case, the refrigerant loop  10  does not operate. 
     &lt;Air Conditioning Defrost and Dehumidification Mode&gt; 
     As shown in  FIG. 8 , based on the heat pump heating mode, the electronic expansion valve  61  is switched to a throttling state in the air conditioning defrost and dehumidification mode. The inner heat exchanger  132  serves as an inner condenser, and the inner heat exchanger  131  serves as an inner evaporator. Moist air is cooled and dehumidified by the inner heat exchanger  131 , then heated by the inner heat exchanger  132 , and then sent to the passenger compartment. In this embodiment, the two inner heat exchangers  131  and  132  are disposed. In addition to the air conditioning defrost and dehumidification mode, a technical effect of full heat exchange in the heat pump heating mode and cooling mode is further achieved. 
     &lt;Battery No Thermal Management Mode&gt; 
     As shown in  FIG. 9 , in the battery no thermal management mode, the refrigerant loop  10  does not operate, and the four-way valve  33  is switched to a state in which the battery heat exchange circulation loop  30  and the motor coolant loop  50  are independent of each other, so that the battery heat exchange circulation loop  30  and the motor coolant loop  50  operate separately. In addition, in the motor coolant loop  50 , the motor coolant flows through the radiator  152  and does not flow through the low pressure chiller  16 . 
     Control logic of the control unit  110  for thermal management of the battery is described below. 
     Refer to  FIG. 12 , first, determining is performed on a battery temperature in block S 10 . When the battery temperature is ≤T 1 , block S 20  is performed: The heat pump heating mode is enabled, active heating is performed by using the motor  51 , and heat is transferred from the motor  51  to the battery  31  through the refrigerant loop  10 . In addition, the battery temperature herein may be obtained by a battery cell temperature sensor in a battery pack. The first preset value T 1  herein is a battery temperature threshold, and for example, may be set to approximately 0 degrees based on experience. In addition, the following second preset value T 2 , third preset value T 3 , and fourth preset value T 4  are also battery temperature thresholds. 
     When T 1 &lt;the battery temperature ≤T 2  (the second preset value), in block S 30 , it is determined whether “a motor outlet water temperature (a temperature measured by a temperature sensor  94 )−the battery temperature” is ≥AΔ T 1  (a first preset difference), that is, it is determined whether the motor outlet water temperature is higher than the battery temperature by at least A T 1 . When a determining result is “yes”, block S 32  is performed: The battery passive heating mode is enabled, so that the motor coolant loop  50  is connected in series to the battery heat exchange circulation loop  30 , to directly heat the battery by using the motor coolant. When a determining result is “no”, block S 40  is performed: The thermal management system  100  is enabled to be in the battery no thermal management mode. The first preset difference ΔT 1  herein is a threshold of a difference between the motor outlet water temperature (in other words, a motor outlet coolant temperature) and the battery temperature. In addition, the motor outlet water temperature herein corresponds to the motor outlet coolant temperature in this application, and is a temperature of the motor coolant when the motor coolant flows out of the motor  51  side. 
     When T 2 &lt;the battery temperature  5  T 3  (the third preset value), block S 50  is performed: It is determined whether “the battery temperature−an ambient temperature” is A T 2  (a second preset difference). When a determining result is “yes”, block S 52  is performed: The battery passive cooling mode is enabled, so that the motor coolant loop  50  is connected in series to the battery heat exchange circulation loop  30 , to cool the battery  31  by using the radiator  152 . When a determining result is “no”, block S 40  is performed: The thermal management system  100  is enabled to be in the battery no thermal management mode. In addition, the second preset difference ΔT 2  herein is a threshold of a difference between the battery temperature and the ambient temperature, and a value of the second preset difference ΔT 2  may be set to a same value as that of the first preset difference ΔT 1 , for example, any value such as 10 degrees. 
     When the battery temperature &gt;T 4  (the fourth preset value), block S 60  is performed: The cooling mode is enabled, so that the refrigerant loop  10  operates for cooling, to cool the battery  31 . 
     In addition, it can be understood from the foregoing descriptions that a temperature value relationship among T 1 , T 2 , T 3 , and T 4  is T 1 &lt;T 2 &lt;T 3 &lt;T 4 . For example, T 2  is set to any value ranging from several degrees to more than 10 degrees, T 3  is set to any value ranging from more than 20 degrees to more than 30 degrees, and T 4  is set to any value ranging from more than 30 degrees to more than 40 degrees. 
     The following describes a variation example of this application with reference to  FIG. 10 . 
       FIG. 10  is a schematic diagram of a structure of a heat exchange circulation loop system of a thermal management system according to a variation example of this application. 
     As shown in  FIG. 10 , a difference between this variation example and the foregoing embodiment lies in that, substituting for the three-way valve  73  in the foregoing embodiment, an electronic expansion valve  64  is disposed in the outer heat exchanger branch  115 , and an electronic expansion valve  65  is disposed in the low pressure chiller branch  116 , so that a same function as that of the three-way valve  73  can be implemented, that is, adjusting refrigerant flow rates of the outer heat exchanger  151  and the low pressure chiller  16 . In the foregoing embodiment, the three-way valve  73  including interfaces with adjustable opening degrees is used, and costs of the three-way valve are relatively high. However, in this variation example, the electronic expansion valves  64  and  65  are used to substitute for the three-way valve  73 , thereby reducing manufacturing costs. 
     In addition, a difference between this variation example and the foregoing embodiment further lies in that, substituting for the three-way valve  71  in the foregoing embodiment, a stop valve  75  is disposed in the first outlet branch  111   a , and a stop valve  76  is disposed in the second outlet branch  111   b ; and substituting for the three-way valve  72  in the foregoing embodiment, a stop valve  77  is disposed in the first inlet branch  112   a , and a stop valve  78  is disposed in the second inlet branch  112   b . The stop valves  75  and  76  and the three-way valve  71  implement a same function, and can alternately switch the first outlet branch  111   a  and the second outlet branch  111   b  between an open state and a closed state. The stop valves  77  and  78  and the three-way valve  72  implement a same function, and can alternately open and close the first inlet branch  112   a  and the second inlet branch  112   b . In this embodiment, the stop valves are used to implement the function, thereby achieving a technical effect of low manufacturing costs. 
     In addition, other structures in this variation example are the same as those in the foregoing embodiment, same reference signs are used in  FIG. 10 , and detailed descriptions thereof are omitted. 
       FIG. 11  is a schematic diagram of a structure of a heat exchange circulation loop system of a thermal management system according to another variation example of this application. 
     The variation example shown in  FIG. 11  is obtained through variation based on  FIG. 10 . A difference between the structure in this variation example and that in  FIG. 10  lies in that, in this variation example, one integrated electronic expansion valve  60  is used to substitute for the electronic expansion valves  62 ,  63 ,  64 , and  65 . The integrated electronic expansion valve  60  integrates four electronic expansion valves  62 A,  63 B,  64 C, and  65 D. The electronic expansion valves  62 A,  63 B,  64 C, and  65 D have same functions as those of the electronic expansion valves  62 ,  63 ,  64 , and  65  respectively. In addition, the four electronic expansion valves  62 A,  63 B,  64 C, and  65 D can share a controller because they are integrated, thereby reducing manufacturing costs. In addition, compared with the structure in  FIG. 10 , pipelines among the electronic expansion valves  62 ,  63 ,  64 , and  65  are changed into inner pipelines among the electronic expansion valves  62 A,  63 B,  64 C, and  65 D, thereby improving operating reliability, reducing an assembly time required for connecting the pipelines, and further reducing manufacturing costs. 
     In addition, a difference between  FIG. 11  and  FIG. 10  further lies in that, in  FIG. 11 , one integrated stop valve  70  is used to substitute for the four stop valves  75 ,  76 ,  77 , and  78 . The integrated stop valve  70  integrates four stop valves  75 A,  76 A,  77 A, and  78 A. The stop valves  75 A,  76 A,  77 A, and  78 A have same functions as those of the stop valves  75 ,  76 ,  77 , and  78  respectively. The four stop valves  75 A,  76 A,  77 A, and  78 A can share a controller because they are integrated, thereby reducing manufacturing costs. In addition, a technical effect of improving reliability and reducing an assembly time is further achieved. 
     The foregoing descriptions are merely example embodiments of this application, but are not intended to limit this application. Any modification, equivalent replacement, or improvement made without departing from the principle of this application should fall within the protection scope of this application. 
     For example, in the foregoing descriptions, a mixture obtained by mixing water and ethylene glycol based on a specific proportion serves as the motor coolant and the heat exchange working medium in the battery heat exchange circulation loop  30 . However, it is self-evident that this application is not limited thereto, and another type of heat exchange working medium may be used. In addition, heat of the refrigerant in the refrigerant loop  10  may be alternatively received by airflow to heat the battery. 
     In addition, in the foregoing descriptions, an example in which the thermal management system is applied to the electric vehicle is used for description. However, this application is not limited thereto, and the thermal management system may be alternatively applied to another scenario with a motor. For example, the thermal management system may be applied to an airplane. In addition, in the foregoing descriptions, the target temperature-controlled space is described by using the passenger compartment of the electric vehicle as an example, and the target temperature-controlled device is described by using the battery as an example. However, the present disclosure is not limited thereto, and the thermal management system may be alternatively applied to thermal management of another space or device that requires temperature control.