Heat pump air-conditioning system with indirect multi-stage waste heat recovery, and control method thereof

Abstract

An indirect multi-level waste heat recovery heat pump air-conditioning system, and a control method therefor. The control method comprises: by means of a compressor, controlling the flow of a refriger

Description

The present disclosure relates to the technical field of thermal management of new energy vehicles, and specifically to a heat pump air-conditioning system with indirect multi-stage waste heat recovery, and a control method thereof. BACKGROUND Mileage is one of the bottlenecks restricting the development of new energy vehicles. In addition to the development of high-capacity and high-density batteries, thermal management technologies for vehicles have also received widespread attention. In low-temperature environments, heat pumps are efficient and can save electric energy and provide a comfortable passenger cabin environment. The battery needs to be heated before being turned on at a low temperature, to avoid severe capacity fading caused by low-temperature discharge. During normal driving, the battery needs to be maintained in a particular temperature range, so that its capacity and service life will not be greatly reduced. In addition, heat generated by the electric drive system and the like needs to be dissipated, and waste heat of the electric drive system and the like also needs to be used to heat the passenger cabin and the battery. However, most conventional direct heat pump air conditioners can only absorb heat from the environment, and do not have a working mode that can recover waste heat of the battery and the electric drive system. SUMMARY To overcome the deficiencies in the prior art, the present disclosure provides a heat pump air conditioning system with indirect multi-stage waste heat recovery, and a control method thereof, to perform multi-stage waste heat recovery at a low temperature, fully cool the battery, the electric drive system, and the cockpit simultaneously at medium and high temperatures, and meet various thermal management requirements under all-weather conditions with low energy consumption. The above technical objective of the present disclosure is attained with the following technical means. A heat pump air-conditioning system with indirect multi-stage waste heat recovery is provided, including: a compressor, a first one-way valve, an outdoor heat exchanger, a second one-way valve, and a gas-liquid separator in communication in sequence, where two ends of the first one-way valve are respectively in communication with a condenser and a first electronic expansion valve, two ends of the second one-way valve are respectively in communication with an evaporator and a second electronic expansion valve, and the two ends of the second one-way valve are further respectively in communication with a third electronic expansion valve and a chiller; a first pump, a first heater, and a heater core in communication in sequence, where the condenser is further in communication with the first pump and the heater core; a second pump, a radiator, an electric drive system, and a three-way valve in communication in sequence; and a third one-way valve, a third pump, a second heater, a power battery, and a fourth one-way valve in communication in sequence, where the third one-way valve is further in communication with the radiator, the fourth one-way valve is further in communication with the three-way valve, and the chiller is further in communication with the third pump and the fourth one-way valve. In the above technical solution, a fan is provided at the radiator. In the above technical solution, a blower is provided at the evaporator and the heater core. In the above technical solution, the compressor, the first one-way valve, the first electronic expansion valve, the second one-way valve, the second electronic expansion valve, the third electronic expansion valve, the first pump, the first heater, the second pump, the three-way valve, the third one-way valve, the third pump, the second heater, the fourth one-way valve, the blower, and the fan are in communication with a control module. A control method of the heat pump air-conditioning system with indirect multi-stage waste heat recovery is provided, including: by the control module, controlling a refrigerant flow rate through the compressor, controlling a coolant flow rate through the first pump, the second pump, and the third pump, controlling an air flow rate through the blower and the fan, controlling a heating power of the first heater and a heating power of the second heater, and controlling circulation and cutoff of fluids or achieving specified flow states of the fluids through the first one-way valve, the first electronic expansion valve, the second one-way valve, the second electronic expansion valve, the third electronic expansion valve, the three-way valve, the third one-way valve, and the fourth one-way valve, to implement the following working modes: a working mode of heating a cockpit by a heat pump in a low-temperature environment, a working mode of heating the cockpit by the heat pump and heating a battery by waste heat of the electric drive system in a low-temperature environment, a working mode of cooling the electric drive system by the radiator in a medium-temperature environment, and a working mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment.Further, the working mode of heating the cockpit by the heat pump in the low-temperature environment is implemented by: controlling the first one-way valve, the second electronic expansion valve, the third electronic expansion valve, the third one-way valve, the fourth one-way valve, the three-way valve, and the second heater to close or turn off, controlling the first electronic expansion valve and the second oneway valve to open, controlling the refrigerant flow rate of the compressor, controlling the coolant flow rate of the first pump, controlling the air flow rate of the fan and the blower, and controlling the heating power of the first heater. Further, the working mode of heating the cockpit by the heat pump and heating the battery by the waste heat of the electric drive system in the low-temperature environment is implemented by: controlling the first one-way valve, the second electronic expansion valve, the third electronic expansion valve, the fourth one-way valve, and a first port of the three-way valve to close, controlling the first electronic expansion valve, the second one-way valve, and the third one-way valve to open, controlling a second port and a third port of the three-way valve to open, controlling the refrigerant flow rate of the compressor, controlling the coolant flow rate of the first pump and the third pump, controlling the air flow rate of the fan and the blower, and controlling the heating power of the first heater and the heating power of the second heater. Further, the working mode of cooling the electric drive system by the radiator in the mediumtemperature environment is implemented by: controlling the first electronic expansion valve, the first one-way valve, the second electronic expansion valve, the second one-way valve, the third electronic expansion valve, a second port of the three-way valve, the first heater, the second heater, and the fourth one-way valve to close or turn off, controlling a first port and a third port of the three-way valve to open, controlling the coolant flow rate of the second pump, and controlling the air flow rate of the fan. Further, the working mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in the high-temperature environment is implemented by: controlling the first electronic expansion valve, the second one-way valve, the first heater, the third one-way valve, and a second port of the three-way valve to close or turn off, controlling the first one-way valve, the second electronic expansion valve, the third electronic expansion valve, and the fourth one-way valve to open, controlling a first port and a third port of the three-way valve to open, controlling the coolant flow rate of the second pump and the third pump, controlling the heating power of the second heater, and controlling the air flow rate of the fan and the blower. A vehicle is provided, including the heat pump air-conditioning system. The present disclosure has the following advantages. (1) The heat pump air-conditioning system of the present disclosure includes a compressor, a first one-way valve, a condenser, a first electronic expansion valve, an outdoor heat exchanger, a second one-way valve, a second electronic expansion valve, an evaporator, a third electronic expansion valve, a chiller, a gas-liquid separator, a first pump, a first heater, a heater core, a second pump, a radiator, an electric drive system, a three-way valve, a third one-way valve, a third pump, a second heater, a power battery, and a fourth one-way valve. The compressor, the first one-way valve, the condenser, the first electronic expansion valve, the outdoor heat exchanger, the second one-way valve, the second electronic expansion valve, the evaporator, the third electronic expansion valve, the chiller, and the gas-liquid separator constitute a heat pump refrigerant loop. The first pump, the first heater, and the heater core constitute a cockpit heating loop. The second pump, the radiator, the electric drive system, the three-way valve, and the third one-way valve constitute an electric drive coolant loop. The third pump, the second heater, the power battery, and the fourth one-way valve constitute a battery coolant loop. The heat pump air-conditioning system of the present disclosure can provide a plurality of working modes by means of a simple topology, thereby meeting different thermal management requirements. (2) The heat pump air-conditioning system of the present disclosure can implement the following working modes: a working mode of heating the cockpit by the heat pump in a low-temperature environment, a working mode of heating the cockpit by the heat pump and heating the battery by waste heat of the electric drive system in a low-temperature environment, a working mode of cooling the electric drive system by the radiator in a medium-temperature environment, and a working mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment. As such, various thermal management requirements under all-weather conditions are met, and energy consumption is reduced by reasonable utilization of waste heat. (3) The working mode of heating the cockpit by the heat pump in a medium- or low-temperature environment in the present disclosure makes use of the circulation of refrigerant in the heat pump to provide heating, thereby reducing the energy consumption of the thermal management system. While the cockpit is heated by the heat pump in a low-temperature environment, the battery can also be heated by waste heat of electric drive system, thereby alleviating problems such as increased internal resistance and severe aging of the battery at a low temperature. Cooling the electric drive system by the radiator in a medium-temperature environment can ensure the thermal safety of the electric drive system in the medium-temperature environment and reduce the energy consumption of thermal management. Cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment ensure the comfort of the cockpit and the safety of thermal management of the electric drive system and the battery at a high temperature and solve the problem of insufficient heat dissipation of the mode of cooling the battery by the radiator at a high temperature. BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the present disclosure can be better understood through the following detailed description with reference to the accompanying drawings, in which like reference numerals denote like parts. FIG. 1 is a diagram of a heat pump air-conditioning system according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of communication connection between a control module and actuators of the heat pump air-conditioning system according to the present disclosure. FIG. 3 is a schematic diagram showing the internal structure of a control module according to the present disclosure. FIG. 4 is a system diagram of the heat pump air-conditioning system in a mode of heating the cockpit by the heat pump in a low-temperature environment according to the present disclosure. FIG. 5 is a system diagram of the heat pump air-conditioning system in a mode of heating the cockpit by the heat pump and heating the battery by waste heat of the electric drive system in a low-temperature environment according to the present disclosure. FIG. 6 is a system diagram of the heat pump air-conditioning system in a mode of cooling the electric drive system by the radiator in a medium-temperature environment according to the present disclosure. FIG. 7 is a system diagram of the heat pump air-conditioning system in a mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment according to the present disclosure. In the drawings, the reference numerals respectively represent: 100 - heat pump air-conditioning system; 101 - compressor; 102 - first one-way valve; 103 - condenser; 104 - first electronic expansion valve; 105 - outdoor heat exchanger; 106 - second one-way valve; 107 - second electronic expansion valve; 108 - evaporator; 109 - third electronic expansion valve; 110 - chiller; 111 - gas-liquid separator; 201 - first pump; 202 - first heater; 203 - heater core; 301 - second pump; 302 - radiator; 303 - electric drive system; 304 - three-way valve; 401 - third one-way valve; 402 - third pump; 403 - second heater; 404 - power battery; 405 - fourth one-way valve; 501 - blower; 502 - fan; 1011 -exhaust port of compressor; 1012 - intake port of compressor; 1021 - first port of first one-way valve; 1022 - second port of first one-way valve; 1031 - refrigerant channel outlet of condenser; 1032 -refrigerant channel inlet of condenser; 1033 - coolant channel outlet of condenser; 1034 - coolant channel inlet of condenser; 1041 - first port of first electronic expansion valve; 1042 - second port of first electronic expansion valve; 1051 - first port of outdoor heat exchanger; 1052 - second port of outdoor heat exchanger; 1061 - first port of second one-way valve; 1062 - second port of second oneway valve; 1071 - first port of second electronic expansion valve; 1072 - second port of second electronic expansion valve; 10 81 - first port of evaporator; 1082 - second port of evaporator; 1091-first port of third electronic expansion valve; 1092 - second port of third electronic expansion valve; 1101 - refrigerant channel outlet of chiller; 1102 - refrigerant channel inlet of chiller; 1103 - coolant channel outlet of chiller; 1104 - coolant channel inlet of chiller; 1 111 - outlet of gas-liquid separator; 1112 - inlet of gas-liquid separator; 2011 - outlet of first pump; 2012 - inlet of first pump; 2021 - first port of first heater; 2022 - second port of first heater; 2031 - first port of heater core; 2032 - second port of heater core; 3011 - outlet of second pump; 3012 - first port of fourth one-way valve; 3021 -first port of radiator; 3022 - second port of radiator; 3031 - first port of electric drive system; 3032 -second port of electric drive system; 3041 - first port of three-way valve; 3042 - second port of three-way valve; 3043 - third port of three-way valve; 4011 - first port of third one-way valve; 4012 -second port of third one-way valve; 4021 - outlet of third pump; 4022 - inlet of third pump; 4031 -first port of second heater; 4032 - second port of second heater; 4041 - first port of power battery; 4042 - second port of power battery; 4051 - first port of fourth one-way valve; 4052 - second port of fourth one-way valve; 8000 - control module; 8001 - bus; 8002 - input interface; 8003 - memory; 8004 - processor; 8005 - output interface; 8101 - interface A; 8102 - interface B; 8103 - interface C; 8104 - interface D; 8105 - interface E; 8106 - interface F; 8107 - interface G; 8108 - interface H; 8109 - interface I; 8110 - interface J; 8111 - interface K; 8112 - interface L; 8113 - interface M; 8114 - interface N; 8115 - interface O; 8116 - interface P; 8200 - connection. DETAILED DESCRIPTION OF THE EMBODIMENTS For ease of understanding of the present disclosure, the present disclosure will be described more fully below with reference to the accompanying drawings. Exemplary embodiments of the present disclosure are shown in the accompanying drawings. However, the present disclosure can be embodied in many different forms and is not limited to the embodiments described herein. For example, electronic expansion valves and one-way valves can be replaced by other appropriate types of valves. Rather, these embodiments are provided for the purpose of providing a more thorough understanding of the present disclosure. Specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings which constitute part of this specification. It is to be understood that ordinal numbers such as "first" and "second" used in the present disclosure are for distinguishing and identifying only, do not have any other meaning, and do not indicate a particular order or a particular relevance unless otherwise specified. For example, for example, the term "first pump" does not imply the presence of a "second pump," and the term "second heater" does not imply the presence of a "first heater". FIG. 1 is a system diagram of a heat pump air-conditioning system 100 according to an embodiment of the present disclosure, showing components in the heat pump air-conditioning system 100 and a connection relationship of the components. As shown in FIG. 1, the heat pump air-conditioning system 100 includes a compressor 101, a first one-way valve 102, a condenser 103, a first electronic expansion valve 104, an outdoor heat exchanger 105, a second one-way valve 106, a second electronic expansion valve 107, an evaporator 108, a third electronic expansion valve 109, a chiller 110, a gas-liquid separator 111, a first pump 201, a first heater 202, a heater core 203, a second pump 301, a radiator 302, an electric drive system 303, a three-way valve 304, a third one-way valve 401, a third pump 402, a second heater 403, a power battery 404, a fourth one-way valve 405, a blower 501, a fan 502, and connection pipelines denoted by connecting lines between the components. Types and functions of the components of the heat pump air-conditioning system 100 are described below. The compressor 101 is a scroll compressor or other types of electric compressors, and is configured to evaporate and compress a refrigerant into superheated steam and push the superheated steam to flow in a refrigerant circulation system. The first pump 201, the second pump 301, and the third pump 402 are electric pumps, which push a coolant to flow in a coolant circulation system. The first pump 201, the second pump 301, and the third pump 402 are all in communication with an external coolant source. The condenser 103 and the chiller 110 are water-side heat exchangers that provide heat exchange between the coolant and the refrigerant. The outdoor heat exchanger 105 and the evaporator 108 are air-side heat exchangers that provide heat exchange between air and the refrigerant. The heater core 203 and the radiator 302 are air-side heat exchangers that provide heat exchange between air and the coolant. The first one-way valve 102, the second one-way valve 106, the third one-way valve 401, and the fourth one-way valve 405 may be one-way solenoid valves or one-way electric valves. The first electronic expansion valve 104, the second electronic expansion valve 107, and the third electronic expansion valve 109 may be solenoid expansion valves or electric expansion valves, the opening degrees of which are controlled to achieve the temperature accuracy of the superheating degree or the supercooling degree. The three-way valve 304 may be a solenoid valve or any other type of valves, as long as a particular communication mode is satisfied. The blower 501 may be various types of electric blowers to provide an air flow required for exchanging heat with the refrigerant of the evaporator 108 and provide an air flow required for exchanging heat with the coolant of the heater core 203. The fan 502 may be various types of fans to provide an air flow required for exchanging heat with the refrigerant of the outdoor heat exchanger 105 and provide an air flow required for exchanging heat with the coolant of the radiator 302. The gas-liquid separator 111 separates the liquid refrigerant and the gaseous refrigerant in the refrigerant loop. In the three-way valve 304, a third port 3043 of the three-way valve is selectively in communication with a second port 3042 of the three-way valve or a first port 3041 of the three-way valve. The first one-way valve 102, the second one-way valve 106, the third one-way valve 401, the fourth one-way valve 405, and the three-way valve 304 are provided for the purpose of controlling connection and disconnection of components close to ports of the valves to achieve different operating modes. The connection pipelines between the components of the heat pump air-conditioning system 100 are described below. An intake port 1012 of the compressor is in communication with an outlet 1111 of the gas-liquid separator. A pipeline node A is in communication with an exhaust port 1011 of the compressor, a refrigerant channel inlet 1032 of the condenser, and a second port 1022 of the first one-way valve. A pipeline node B is in communication with a first port 1021 of the first oneway valve, a first port 1041 of the first electronic expansion valve, and a second port 1052 of the outdoor heat exchanger. A refrigerant channel outlet 1031 of the condenser is in communication with a second port 1042 of the first electronic expansion valve. A pipeline node C is in communication with a first port 1051 of the outdoor heat exchanger, a pipeline node D, and a second port 1092 of the third electronic expansion valve. A refrigerant channel inlet 1102 of the chiller is in communication with a first port 1091 of the third electronic expansion valve. The pipeline node D is in communication with the pipeline node C, a second port 1062 of the second one-way valve, and a second port 1072 of the second electronic expansion valve. A second port 1082 of the evaporator is in communication with a first port 1071 of the second electronic expansion valve. A pipeline node E is in communication with a pipeline node F, a first port 1061 of the second one-way valve, and a first port 10 81 of the evaporator. The pipeline node F is in communication with a refrigerant channel outlet 1101 of the chiller, the pipeline node E, and an inlet 1112 of the gas-liquid separator. An outlet 2011 of the first pump is in communication with a second port 2022 of the first heater. A second port 2032 of the heater core is in communication with a first port 2021 of the first heater. A coolant channel inlet 1034 of the condenser is in communication with a first port 2031 of the heater core. An inlet 2012 of the first pump is in communication with a coolant channel outlet 1033 of the condenser. An outlet 3011 of the second pump is in communication with a second port 3022 of the radiator. A pipeline node G is m communication with a first port 3021 of the radiator, a second port 3032 of the electric drive system, and a second port 4012 of the third one-way valve. A pipeline node H is in communication with a first port 4011 of the third one-way valve, an inlet 4022 of the third pump, and a coolant channel outlet 1103 of the chiller. A second port 4032 of the second heater is in communication with an outlet 4021 of the third pump. A second port 4042 of the power battery is in communication with a first port 4031 of the second heater. A pipeline node I is in communication with a first port 4041 of the power battery, a second port 3042 of the three-way valve, and a second port 4052 of the fourth one-way valve. A coolant channel inlet 1104 of the chiller is in communication with a first port 4051 of the fourth one-way valve. The first port 3041 of the three-way valve is in communication with an inlet 3012 of the second pump. A first port 3031 of the electric drive system is in communication with the third port 3043 of the three-way valve. The fan 502 provides an air flow required for exchanging heat with the refrigerant in the outdoor heat exchanger 105. The fan 502 provides an air flow required for exchanging heat with the coolant in the radiator 302. The blower 501 provides an air flow required for exchanging heat with the refrigerant in the evaporator 108. The blower 501 provides an air flow required for exchanging heat with the coolant in the heater core 203. The heat pump air-conditioning system of the present disclosure can provide a plurality of working modes by means of a simple topology, thereby meeting different thermal management requirements. FIG. 2 is a schematic diagram of communication connection between a control module and actuators of the heat pump air-conditioning system. As shown in FIG. 2, a control module 8000 determines operating statuses of the actuators of the heat pump air-conditioning system 100. An interface A 8101, an interface B 8102, an interface C 8103, an interface D 8104, an interface E 8105, an interface F 8106, an interface G 8107, an interface H 8108, an interface I 8109, an interface J 8110, an interface K 8111, an interface L 8112, an interface M 8113, an interfaceN 8114, an interface O 8115, and an interface P 8116 of an output interface 8005 of the control module 8000 are respectively in communication with the compressor 101, the first one-way valve 102, the first electronic expansion valve 104, the second one-way valve 106, the second electronic expansion valve 107, the third electronic expansion valve 109, the first pump 201, the first heater 202, the second pump 301, the three-way valve 304, the third one-way valve 401, the third pump 402, the second heater 403, the fourth one-way valve 405, the blower 501, and the fan 502. The control module 8000 controls a refrigerant flow rate through the compressor 101. The control module 8000 controls a coolant flow rate through the first pump 201, the second pump 301, and the third pump 402. The control module 8000 controls a heating power of the first heater 202 and a heating power of the second heater 403. The control module 8000 controls circulation and cutoff of the fluids or achieves specified flow states of the fluids through the first one-way valve 102, the first electronic expansion valve 104, the second one-way valve 106, the second electronic expansion valve 107, the third electronic expansion valve 109, the three-way valve 304, the third one-way valve 401, and the fourth one-way valve 405. The control module 8000 controls an air flow rate through the blower 501 and the fan 502. FIG. 3 is a schematic diagram showing the internal structure of the control module. As shown in FIG. 3, the control module 8000 includes a bus 8001, an input interface 8002, a memory 8003, a 12 processor 8004, and an output interface 8005. Specifically, the memory 8003 is configured to store a program, an instruction, and data, and the processor 8004 reads the program, the instruction, and the data from the memory 8003, and can write data to the memory 8003. By executing the program and the instruction that are read from the memory 8003, the processor 8004 implements signal exchange through the input interface 8002 and the output interface 8004. As shown in FIG. 3, the input interface 8002 of the control module 8000 receives an operating request and other operating parameters of the heat pump air-conditioning system 100 through a connection 8200. By executing the program and the instruction in the memory 8003, the processor 8004 controls operation of the heat pump air-conditioning system 100. Specifically, the control module 8000 may receive an operation request for controlling the heat pump air-conditioning system 100 or a signal for controlling other components through the input interface 8002, and send a control signal to the controlled components through the output interface 8005, thereby enabling the heat pump air-conditioning system 100 to operate in a specified working mode and switch between different modes. FIG. 4 to FIG. 7 show flow states of fluids in the heat pump air-conditioning system 100 operating in different working modes, where hollow arrows represent the flow direction and flow path of the refrigerant, thick solid arrows represent the flow direction and flow path of the coolant, and other solid lines indicate that there is no fluid flowing. The working modes shown in FIG. 4 to FIG. 7 are described m detail below. FIG. 4 is a system diagram of the heat pump air-conditioning system 100 in a mode of heating a cockpit by the heat pump in a low-temperature environment. In a low-temperature environment, the heat pump air-conditioning system 100 may transfer heat to the cockpit through a heat pumpbased heating mode after receiving a cockpit heating instruction (or the control module 8000 automatically generates a cockpit heating instruction). Specifically, the first one-way valve 102, the second electronic expansion valve 107, the third electronic expansion valve 109, the third one-way valve 401, the fourth one-way valve 405, the three-way valve 304, and the second heater 403 are controlled to close or turn off, the first electronic expansion valve 104 and the second one-way valve 106 are controlled to open, a refrigerant flow rate of the compressor 101 is controlled, a coolant flow rate of the first pump 201 is controlled, air flow rates of the fan 502 and the blower 501 are controlled, and the heating power of the first heater 202 is controlled. As shown in FIG. 4, the high-temperature and high-pressure refrigerant flowing out of the exhaust port 1011 of the compressor flows into the refrigerant channel inlet 1032 of the condenser through the pipeline node A, and is condensed from a gaseous state to a liquid state by the condenser 103. The high-pressure refrigerant in the liquid state flows out from the refrigerant channel outlet 1031 of the condenser. After passing through the first electronic expansion valve 104, the high-pressure refrigerant in the liquid state experiences a pressure drop and volume expansion and changes into a low-temperature and low-pressure liquid mist mixture, which then flows to the second port 1052 of the outdoor heat exchanger through the pipeline node B. At this moment, the outdoor heat exchanger 105 serves as an evaporator, which absorbs a large amount of heat from ambient air, so that the refrigerant changes to the gaseous state, flows out from the first port 1051 of the outdoor heat exchanger, flows through the pipeline node C, the pipeline node D, the second one-way valve 106, the pipeline node E, and the pipeline node F in sequence, and then flows into the inlet 1112 of the gas-liquid separator. The liquid refrigerant and the gaseous refrigerant are separated through the gas-liquid separator 111. The intake port 1012 of the compressor sucks the gaseous refrigerant from the outlet 1111 of the gas-liquid separator to start a next refrigerant cycle. On the other hand, when flowing through a coolant channel of the condenser 103, the low-temperature coolant absorbs heat of the refrigerant and changes to a high-temperature coolant. Then, the high-temperature coolant is pumped out through the outlet 2011 of the first pump and flows into the second port 2022 of the first heater. The first heater 202 may release heat to the coolant as required, thereby improving the power of cockpit heating and the system efficiency. Then, the coolant flows from the first port 2021 of the first heater to the second port 2032 of the heater core. When flowing through the heater core 203, the high-temperature coolant releases heat to air blown from the blower 501 to heat the cockpit, and changes back to a low-temperature coolant at the first port 2031 of the heater core, which then flows into the inlet 2012 of the first pump through a coolant channel of the condenser 103. As such, a coolant cycle for cockpit heating is completed. FIG. 5 is a system diagram of the heat pump air-conditioning system 100 in a mode of heating the cockpit by the heat pump and heating the battery by waste heat of the electric drive system in a low-temperature environment. When the heat pump air-conditioning system 100 identifies that the heat pump efficiency is low and the coolant temperature at the outlet of the electric drive system 302 is high, waste heat of the electric drive system may be directly used to heat the battery. Specifically, the first one-way valve 102, the second electronic expansion valve 107, the third electronic expansion valve 109, the fourth one-way valve 405, and the first port of the three-way valve 304 are controlled to close, the first electronic expansion valve 104, the second one-way valve 106, and the third oneway valve 401 are controlled to open, the second port and the third port of the three-way valve 304 are controlled to open, a refrigerant flow rate of the compressor 101 is controlled, coolant flow rates of the first pump 201 and the third pump 402 are controlled, air flow rates of the fan 502 and the blower 501 are controlled, and the heating power of the first heater 202 and the heating power of the second heater 403 are controlled. The refrigerant cycle and the cockpit heating cycle in this mode are exactly the same as those in the working mode shown in FIG. 4, so the details will not be repeated herein. In this mode, the temperature of the coolant at the second port 3032 of the electric drive system is high, and the high-temperature coolant flows into the inlet 4022 of the third pump through the pipeline node G, the third one-way valve 401, and the pipeline node H in sequence. The high-temperature coolant flows out from the outlet 4021 of the third pump and flows into the second port 4042 of the power battery through the second heater 403. The high-temperature coolant heats the power battery 404 and changes into a low-temperature coolant at the first port 4041 of the power battery, which then flows into the first port 3031 of the electric drive system through the pipeline node I, the second port 3042 of the three-way valve, and the third port 3043 of the three-way valve. As such, a coolant cycle for heating the battery with waste heat of the electric drive is completed. FIG. 6 is a system diagram of the heat pump air-conditioning system 100 in a mode of cooling the electric drive system by the radiator in a medium-temperature environment. In a medium temperature environment, the electric drive system needs to be cooled when there is no need for heating or cooling the cockpit. Generally, in this environment, the temperature is appropriate, the amount of heat generated by the electric drive system is not large, and the radiator can be used to dissipate heat of the electric drive system, thereby reducing the compressor load and therefore reducing the energy consumption of the compressor. Specifically, the first electronic expansion valve 104, the first one-way valve 102, the second electronic expansion valve 107, the second one-way valve 106, the third electronic expansion valve 109, the second port of the three-way valve 304, the first heater 202, the second heater 403, and the fourth one-way valve 405 are controlled to close or turn off, the first port and the third port of the three-way valve 304 are controlled to open, a coolant flow rate of the second pump 301 is controlled, and an air flow rate of the fan 502 is controlled. In this mode, the high-temperature coolant pumped from the outlet 3011 of the second pump flows into the second port 3022 of the radiator. Under the control of the fan 502, the high-temperature coolant at the second port 3022 of the radiator exchanges heat with air and is thus cooled down to form a low-temperature coolant at the first port 3021 of the radiator, which then flows into the second port 3032 of the electric drive system through the pipeline node G for cooling. Then, the coolant flows out from the first port 3031 of the electric drive system, flows through the third port 3043 of the three-way valve and the first port 3041 of the three-way valve, and then flows into the second port 3012 of the second pump. As such, a cycle of cooling the electric drive radiator in a mediumtemperature environment is completed. FIG. 7 is a system diagram of the heat pump air-conditioning system 100 in a mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment. When the temperature of ambient air is high, the high-temperature coolant for the battery cannot exchange heat with the ambient air through the radiator, so the battery needs to be cooled by the chiller. When the heat pump air-conditioning system 100 receives a cockpit air-conditioning cooling instruction (or the control module 8000 automatically generates a cockpit cooling instruction), the refrigerant circulates to cool the cockpit. Specifically, the first electronic expansion valve 104, the second one-way valve 106, the first heater 202, the third one-way valve 401, and the second port of the three-way valve 304 are controlled to close or turn off, the first one-way valve 102, the second electronic expansion valve 107, the third electronic expansion valve 109, and the fourth one-way valve 405 are controlled to open, the first port and the third port of the three-way valve 304 are controlled to open, coolant flow rates of the second pump 301 and the third pump 402 are controlled, the heating power of the second heater 403 is controlled, and air flow rates of the fan 502 and the blower 501 are controlled. The high-temperature and high-pressure refrigerant flowing out from the exhaust port 1011 of the compressor flows into the second port 1052 of the outdoor heat exchanger after flowing through the pipeline node A, the first one-way valve 102, and the pipeline node B. At this moment, the outdoor heat exchanger 105 serves as a condenser, which condenses the refrigerant in the gaseous state into a liquid state, during which process the refrigerant dissipates heat to the environment. The refrigerant flows out from the first port 1051 of the outdoor heat exchanger and flows into the partially opened second port 1072 of the second electronic expansion valve after flowing through the pipeline node C and the pipeline node D in sequence. After passing through the second electronic expansion valve, the refrigerant experiences a pressure drop and volume expansion and changes into a low-temperature and low-pressure liquid mist mixture, which flows out from the first port 1071 of the second electronic expansion valve to the second port 1082 of the evaporator. At this moment, the refrigerant absorbs heat from air blown from the blower 501, and the humidity is lowered by cooling of the air. The refrigerant flows from the first port 10 81 of the evaporator and flows into the second port 1112 of the gas-liquid separator through the pipeline node E and the pipeline node F. In addition, when the refrigerant flows through the pipeline node C, a part of the refrigerant flows into the second port 1092 of the third electronic expansion valve. After passing through the third electronic expansion valve, this part of the refrigerant experiences a pressure drop and volume expansion and changes into a low-temperature and low-pressure liquid mist mixture, which flows out from the first port 1091 of the third electronic expansion valve to the refrigerant channel inlet 1102 of the chiller. At this moment, the refrigerant exchanges heat with the coolant pumped by the third pump 402 in the chiller 110 to enter a low-temperature and low-pressure state. Then, the refrigerant flowing out of the refrigerant channel outlet 1101 of the chiller flows into the second port 1112 of the gas-liquid separator through the pipeline node F. The liquid refrigerant and the gaseous refrigerant are separated through the gasliquid separator 111. The intake port 1012 of the compressor sucks the gaseous refrigerant from the outlet 1111 of the gas-liquid separator to start a next refrigerant cycle. The cooling of the electric drive system by the radiator in this mode is exactly the same as that in FIG. 6, so the details will not be repeated herein. The difference between this mode and the mode shown in FIG. 6 lies in that the high-temperature coolant pumped from the outlet 4021 of the third pump flows into the coolant channel inlet 1104 of the chiller through the second heater 403, the power battery 404, the pipeline node I, and the fourth one-way valve 405, and exchanges heat with the refrigerant to form a low-temperature coolant at the coolant channel outlet 1103 of the chiller, which then flows into the inlet 4022 of the third pump through the pipeline node H. As such, a cycle of cooling the battery by the chiller is completed. In the above working modes, the refrigerant flow rate of the compressor 101 is controlled by controlling the rotational speed of the compressor 101, the coolant flow rates of the first pump 201, the second pump 301, and the third pump 402 are controlled by controlling the rotational speeds of the first pump 201, the second pump 301, and the third pump 402, the air flow rates of the fan 502 and the blower 501 are controlled by controlling the rotational speeds of the fan 502 and the blower 501, the heating power of the first heater 202 and the heating power of the second heater 403 are controlled by controlling the currents of the first heater 202 and the second heater 403, and the control of the rotational speeds and the currents is determined according to thermal management requirements, and belongs to the prior art. Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments. Any obvious improvement, replacement or variation that can be made by those skilled in the art without departing from the essence of the present disclosure falls within the protection scope of the present disclosure.

Claims

1. A heat pump air-conditioning system with indirect multi-stage waste heat recovery, characterized by comprising:a compressor (101), a first one-way valve (102), an outdoor heat exchanger (105), a second one-way valve (106), and a gas-liquid separator (111) in communication in sequence, wherein two ends of the first one-way valve (102) are respectively in communication with a condenser (103) and a first electronic expansion valve (104), two ends of the second one-way valve (106) are respectively in communication with an evaporator (108) and a second electronic expansion valve (107), and the two ends of the second one-way valve (106) are further respectively in communication with a third electronic expansion valve (109) and a chiller (110);a first pump (201), a first heater (202), and a heater core (203) in communication in sequence, wherein the condenser (103) is further in communication with the first pump (201) and the heater core(203);a second pump (301), a radiator (302), an electric drive system (303), and a three-way valve (304) in communication in sequence; anda third one-way valve (401), a third pump (402), a second heater (403), a power battery (404), and a fourth one-way valve (405) in communication in sequence, wherein the third one-way valve (401) is further in communication with the radiator (302), the fourth one-way valve (405) is further in communication with the three-way valve (304), and the chiller (110) is further in communication with the third pump (402) and the fourth one-way valve (405).

2. The heat pump air-conditioning system according to claim 1, characterized in that a fan (502) is provided at the radiator (302).

3. The heat pump air-conditioning system according to claim 2, characterized in that a blower (501) is provided at the evaporator (108) and the heater core (203).

4. The heat pump air-conditioning system according to claim 3, characterized in that the compressor (101), the first one-way valve (102), the first electronic expansion valve (104), the second one-way valve (106), the second electronic expansion valve (107), the third electronic expansion valve (109), the first pump (201), the first heater (202), the second pump (301), the three-way valve (304), the third one-way valve (401), the third pump (402), the second heater (403), the fourth one-way valve (405), the blower (501), and the fan (502) are in communication with a control module (8000).

5. A control method of the heat pump air-conditioning system according to any one of claims 1 to 4, characterized by comprising:by the control module (8000), controlling a refrigerant flow rate through the compressor (101), controlling a coolant flow rate through the first pump (201), the second pump (301), and the third pump (402), controlling an air flow rate through the blower (501) and the fan (502), controlling a heating power of the first heater (202) and a heating power of the second heater (403), and controlling circulation and cutoff of fluids or achieving specified flow states of the fluids through the first oneway valve (102), the first electronic expansion valve (104), the second one-way valve (106), the second electronic expansion valve (107), the third electronic expansion valve (109), the three-way valve (304), the third one-way valve (401), and the fourth one-way valve (405), to implement the following working modes: a working mode of heating a cockpit by a heat pump in a low-temperature environment, a working mode of heating the cockpit by the heat pump and heating a battery by waste heat of the electric drive system in a low-temperature environment, a working mode of cooling the electric drive system by the radiator in a medium-temperature environment, and a working mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator, and cooling the battery by the chiller in a high-temperature environment.

6. The control method according to claim 5, characterized in that the working mode of heating the cockpit by the heat pump in the low-temperature environment is implemented by:controlling the first one-way valve (102), the second electronic expansion valve (107), the third electronic expansion valve (109), the third one-way valve (401), the fourth one-way valve (405), the three-way valve (304), and the second heater (403) to close or turn off, controlling the first electronic expansion valve (104) and the second one-way valve (106) to open, controlling the refrigerant flow rate of the compressor (101), controlling the coolant flow rate of the first pump (201), controlling the air flow rate of the fan (502) and the blower (501), and controlling the heating power of the first heater (202).

7. The control method according to claim 5, characterized in that the working mode of heating the cockpit by the heat pump and heating the battery by the waste heat of the electric drive system in the low-temperature environment is implemented by:controlling the first one-way valve (102), the second electronic expansion valve (107), the third electronic expansion valve (109), the fourth one-way valve (405), and a first port of the three-way valve (304) to close, controlling the first electronic expansion valve (104), the second one-way valve (106), and the third one-way valve (401) to open, controlling a second port and a third port of the three-way valve (304) to open, controlling the refrigerant flow rate of the compressor (101), controlling the coolant flow rate of the first pump (201) and the third pump (402), controlling the air flow rate of the fan (502) and the blower (501), and controlling the heating power of the first heater (202) and the heating power of the second heater (403).

8. The control method according to claim 5, characterized in that the working mode of cooling the electric drive system by the radiator in the medium-temperature environment is implemented by: controlling the first electronic expansion valve (104), the first one-way valve (102), the second electronic expansion valve (107), the second one-way valve (106), the third electronic expansion valve (109), a second port of the three-way valve (304), the first heater (202), the second heater (403), and the fourth one-way valve (405) to close or turn off, controlling a first port and a third port of the three-way valve (304) to open, controlling the coolant flow rate of the second pump (301), and controlling the air flow rate of the fan (502).

9. The control method according to claim 5, characterized in that the working mode of cooling the cockpit by the heat pump air-conditioning system, cooling the electric drive system by the radiator,and cooling the battery by the chiller in the high-temperature environment is implemented by: controlling the first electronic expansion valve (104), the second one-way valve (106), the first heater (202), the third one-way valve (401), and a second port of the three-way valve (304) to close or turn off, controlling the first one-way valve (102), the second electronic expansion valve (107), the third electronic expansion valve (109), and the fourth one-way valve (405) to open, controlling a first port and a third port of the three-way valve (304) to open, controlling the coolant flow rate of the second pump (301) and the third pump (402), controlling the heating power of the second heater (403), and controlling the air flow rate of the fan (502) and the blower (501).

10. A vehicle, characterized by comprising the heat pump air-conditioning system according to any one of claims 1 to 4.