Multi-source heat pump control method and system for thermal management of pure electric vehicle and medium

Abstract

The invention relates to the technical field of thermal management of electric vehicles, in particular to a multi-source heat pump control method and system for thermal management of a pure electric vehicle and a medium, and the method comprises the following steps: selecting a corresponding multi-source heat pump control mode according to heating or refrigerating requests sent by a passenger compartment and a battery in combination with vehicle conditions, vehicle speed and environment temperature; measuring the surface temperature T7 of the warm air core; the difference value delta T7 between the surface temperature T7 of the warm air core and the target temperature T7m of the warm air core is calculated, and PI adjustment is conducted on the rotating speed of a compressor according to the difference value delta T7; by adjusting the opening degree of the three-way valve D, the heating requirement of the battery or the passenger compartment is met. According to the actual running state of the vehicle, multiple heat sources can be selected in good time, electric drive waste heat is fully utilized, and energy waste is avoided; the electric automobile can work in the field of the extremely low temperature of-40 DEG C, and the cruising ability of the electric automobile in winter and the comfort level of passengers are guaranteed. Therefore, the technical problems that an existing heat management system is low in heating efficiency and insufficient in heating capacity can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management of electric vehicles, and in particular to a thermal management multi-source heat pump control method, system and medium for a pure electric vehicle. Background Art

[0002] With the development of the automotive industry, especially the rise of new energy vehicles, higher requirements have been placed on automotive thermal management systems. Traditional fuel vehicles mainly focus on engine cooling and cabin air conditioning, while pure electric vehicles, which do not have the waste heat generated by the internal combustion engine to utilize, must more efficiently manage the thermal state of key components such as battery packs and drive motors, as well as the comfort of the passenger compartment, while also considering the impact of energy efficiency and range. In addition, due to insufficient heating capacity and low heating efficiency, existing thermal management systems may have the following risks: poor cabin heating in winter, fluctuating temperatures, and failure to meet passenger needs; cabin defrosting and defoggering functions cannot be achieved or are imperfect in winter; batteries are overcooled or overheated in winter, and control is unstable, affecting life; batteries consume a lot of power in winter and have poor range.

[0003] Because the existing thermal management system generally uses a single heat pump mode, the commonly used ones are electric drive source heat pump, air source heat pump, and PTC heat pump. When both the passenger compartment and the battery in the thermal management system have heating needs, the compressor speed is not enough due to more or less changes in the loads on both sides, resulting in insufficient heating capacity and low heating efficiency. Specifically, when the electric drive waste heat source is insufficient, the system mode is directly switched to air source or PTC heat source, resulting in insufficient application of electric drive waste heat, resulting in insufficient system heating capacity. In the air source heat pump mode, the fan power is too large, resulting in low energy efficiency of the thermal management system, resulting in low system heating efficiency. In the PTC heat pump mode, the PTC power is too small, resulting in insufficient heating of the thermal management system, resulting in insufficient system heating capacity; or the PTC power is too large, resulting in the problem of compressor cutting off, which causes safety accidents and affects the battery life.

[0004] CN118494101A; Suzhou Research Institute of Hunan University; This invention can heat the battery and passenger compartment quickly in extremely low temperature environments. It can improve heat utilization, reduce system energy consumption, and make the thermal management system more flexible, so that the car air conditioner can automatically select the corresponding heating / cooling mode according to different ambient temperatures to adjust the thermal balance between the passenger compartment and the battery pack. However, the heat source is relatively single, the energy-saving control method is relatively simple, and the heating efficiency is low, which easily leads to the problem of insufficient heating of the thermal management system.

[0005] CN118494141A; BYD Co., Ltd.; This invention controls the temperature of the refrigerant at the inlet of the first heat exchanger to achieve uniform temperature treatment of the battery, thereby reducing the temperature difference of the battery, making the battery have better charging uniformity and extending the service life of the battery. However, the control method and demand response are relatively simple, the heating efficiency is low, and it is easy to cause the problem of insufficient heating of the thermal management system.

[0006] CN118514487A; Guangzhou Automobile Group Co., Ltd.; This invention determines whether there is a risk of frost on the evaporator during the compressor speed-up process when performing heating and dehumidification. When there is a risk of frost on the evaporator, the compressor speed is no longer increased to avoid frost on the evaporator and ensure the dehumidification effect of the evaporator. However, the control of the compressor speed and the ability to widen the temperature range is poor, which easily leads to insufficient heating of the thermal management system.

[0007] To summarize, the existing thermal management system adopts a single heat pump mode, which has poor control over the compressor speed, resulting in insufficient system heating capacity and low heating efficiency, thus affecting the cruising range and battery life. Summary of the invention

[0008] The purpose of the present invention is to provide a pure electric vehicle thermal management multi-source heat pump control method, system and medium, which can solve the technical problems of existing thermal management systems due to low heating efficiency and insufficient heating capacity, thereby affecting the cruising range and battery life.

[0009] To achieve the above object, the present invention designs a pure electric vehicle thermal management multi-source heat pump control method, comprising the following steps:

[0010] According to the heating or cooling request from the passenger compartment and the battery, the corresponding multi-source heat pump control mode is selected in combination with the vehicle condition, vehicle speed and ambient temperature;

[0011] Measure the surface temperature T7 of the heater core;

[0012] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and perform PI adjustment on the compressor speed according to the difference ΔT7;

[0013] For the high-temperature heating circuit, the opening of the three-way valve D is adjusted to meet the heating needs of the battery or the passenger compartment respectively;

[0014] For the low-temperature cooling circuit, according to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recovering the low-temperature heat in the air to meet the battery cooling needs.

[0015] As a preferred solution, the multi-source heat pump control mode includes an electric drive source heat pump control mode, an electric drive waste heat + hot gas bypass control mode, an air source heat pump + PTC control mode, and a battery source heat pump control mode.

[0016] As a preferred solution, when the passenger compartment and the battery both send out heating requests during driving, the electric drive and electric control water outlet temperature T3 is greater than -20°C, and the ambient temperature can be as low as -40°C, the electric drive source heat pump control mode is selected. The high temperature heating circuit and low temperature cooling circuit of the electric drive source heat pump control mode are as follows:

[0017] For the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively;

[0018] For the low-temperature cooling circuit, the electric drive and electronic control water outlet temperature T3 is measured, and the opening of the three-way valve E and the switch of the electronic fan are controlled according to the electric drive and electronic control water outlet temperature T3 and the vehicle speed to recover part of the electric drive and electronic control heat or discharge excess heat of the electric drive and electronic control to the outside of the vehicle, so that the temperature of the electric drive and electronic control reaches the target range value.

[0019] As a preferred solution, when the passenger compartment and the battery both issue a heating request during driving, the electric drive and electric control water outlet temperature T3 is less than -20°C, and the ambient temperature can be as low as -40°C. The electric drive waste heat + hot gas bypass control mode is selected. The high temperature heating circuit and low temperature cooling circuit of the electric drive waste heat + hot gas bypass control mode are as follows:

[0020] For the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively;

[0021] For the low-temperature cooling circuit, the electric drive and electronic control water outlet temperature T3 is measured, and the difference ΔT3 between the electric drive and electronic control water outlet temperature T3 and the electric drive and electronic control minimum temperature T3m is calculated. The first electronic expansion valve performs PI dynamic adjustment according to the difference ΔT3 to recover a small amount of heat from the electric drive and electronic control so that the temperature of the electric drive and electronic control reaches the target range value.

[0022] Furthermore, in the electric drive waste heat + hot gas bypass control mode, the following steps are also included before the compressor speed is PI-regulated according to the difference ΔT7:

[0023] When the compressor inlet temperature pressure PT2 has a pressure P ≥ 1.5 bar, the compressor speed is PI-regulated according to the difference ΔT7;

[0024] When the pressure P in the compressor inlet temperature and pressure PT2 is less than 1.5 bar, the pressure difference ΔP between the measured P value of the compressor inlet temperature and pressure PT2 and the target pressure is measured, and PI dynamic adjustment is performed through the second electronic expansion valve to supply air to the compressor, so that the pressure P in the compressor inlet temperature and pressure PT2 is ≥ 1.5 bar, and then the compressor speed is PI adjusted according to the difference ΔT7.

[0025] As a preferred solution, in the parking condition where both the passenger compartment and the battery send heating requests, the vehicle speed is 0 km / h, and the ambient temperature is -20°C to 15°C, the air source heat pump + PTC control mode is selected. The high-temperature heating circuit and the low-temperature cooling circuit of the air source heat pump + PTC control mode are as follows:

[0026] For the high-temperature heating circuit, measure the coolant temperature T4 at the PTC outlet and compare it with its target temperature T4m; if T4 > T4m, proceed to the next step; if T4 < T4m, turn on the PTC, and the PTC performs PI dynamic adjustment according to the difference ΔT4 between its outlet coolant temperature T4 and its target temperature T4m, and then proceed to the next step;

[0027] Measure the battery inlet temperature T5, and adjust the opening of the three-way valve D according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively;

[0028] For the low-temperature cooling circuit, measure the P value of the compressor inlet temperature and pressure PT2, and adjust the gear of the electric fan according to the P value of PT2 to recover the low-temperature heat in the air.

[0029] As a preferred solution, in the driving condition where the passenger compartment sends a heating request and the battery sends a cooling request, the vehicle speed is greater than 0 km / h, and the ambient temperature is 5°C to 15°C, the battery source heat pump control mode is selected. The high-temperature heating circuit and the low-temperature cooling circuit of the battery source heat pump control mode are as follows:

[0030] For the high-temperature heating circuit, measure the coolant temperature T4 at the PTC outlet, calculate the difference ΔT4 between the coolant temperature T4 at the PTC outlet and its target temperature T4m, and adjust the opening of the three-way valve D according to the magnitude of the difference ΔT4 to meet the heating requirements of the passenger compartment;

[0031] For the low-temperature cooling circuit, measure the battery outlet temperature T6, calculate the difference ΔT6 between the battery outlet temperature T6 and the target temperature T6m, and the first electronic expansion valve performs PI adjustment according to the difference ΔT6; adjust the four-way valve A, the three-way valve C, and the four-way valve B respectively, and then pass through the low-temperature electric water pump to the water-cooled evaporator to meet the battery cooling requirements.

[0032] Further, in the battery source heat pump control mode, if ΔT4 ≥ 3, adjust the three-way valve D to reserve the electric drive and electronic control heat storage, specifically as follows:

[0033] If 3≤ΔT4≤7, adjust the duty cycle of the three-way valve D(1-2) to 5%, and the duty cycle of (1-3) to 95%, and at the same time, the electric drive and electric control store heat for standby;

[0034] If 7<ΔT4<15, adjust the duty cycle of the three-way valve D(1-2) to 20%, and the duty cycle of (1-3) to 80%, and at the same time, the electric drive and electric control store heat for standby;

[0035] If ΔT4≥15, adjust the duty cycle of the three-way valve D(1-2) to 50%, and the duty cycle of (1-3) to 50%, and at the same time, the electric drive and electric control store heat for standby.

[0036] The present invention also designs a pure electric vehicle thermal management multi-source heat pump control system, including a multi-source heat pump selection module, a heater core temperature measurement module, a PI adjustment module, a high-temperature cooling module, and a low-temperature cooling module;

[0037] The multi-source heat pump selection module is used to select a corresponding multi-source heat pump control mode according to the heating or cooling request issued by the passenger compartment and the battery in combination with the vehicle condition, vehicle speed and ambient temperature;

[0038] The heater core temperature measurement module is used to measure the heater core surface temperature T7;

[0039] The PI adjustment module is used to calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and the compressor speed is PI-adjusted according to the difference ΔT7;

[0040] The high temperature cooling module is used for the high temperature heating circuit to meet the heating requirements of the battery or the passenger compartment respectively by adjusting the opening of the three-way valve D;

[0041] The low-temperature cooling module is used for the low-temperature cooling circuit. According to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recover the low-temperature heat in the air, and meet the battery cooling needs.

[0042] The present invention also designs a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned pure electric vehicle thermal management multi-source heat pump control method are implemented.

[0043] Beneficial effects of the present invention:

[0044] The electric vehicle thermal management system of the present invention adopts a multi-source heat pump control mode, which can realize timely selection of multiple heat sources according to the actual operating status of the vehicle, make full use of electric drive waste heat, avoid energy waste, and effectively improve heating capacity and heating efficiency.

[0045] 2) It can operate in the extremely low temperature range of -40℃, ensuring the endurance and passenger comfort of electric vehicles in winter, and further significantly improving the heating capacity.

[0046] 3) Through intelligent control strategies, the compressor is placed at a better compression ratio, which improves system energy efficiency, extends the compressor service life, and further significantly improves heating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a structural diagram of the present invention for heating the passenger compartment and the battery simultaneously.

[0048] Figure 2 This is a flow chart of the electric drive source heat pump control mode of the present invention.

[0049] Figure 3 This is a flow chart of the electric drive waste heat + hot gas bypass control mode of the present invention.

[0050] Figure 4 This is a flow chart of the air source heat pump + PTC control mode of the present invention.

[0051] Figure 5 This is a schematic diagram of the battery source heat pump control mode of the present invention.

[0052] Figure 6 This is a flow chart of the battery source heat pump control mode of the present invention.

[0053] Description of reference numerals:

[0054] Refrigerant circuit: compressor 1, plate-type water-cooled condenser 2, first electronic expansion valve 3, plate-type water-cooled evaporator 4, second electronic expansion valve 17;

[0055] Low-temperature cooling circuit: low-temperature electronic water pump 12, low-temperature radiator 13, electronic fan 14, electric drive and electronic control 15, low-temperature expansion kettle 16, three-way valve E, four-way valve A, four-way valve B;

[0056] High temperature heating circuit: high temperature electronic water pump 5, PTC 6, heater core 7, blower 9, battery 10, high temperature expansion kettle 11, three-way valve C, three-way valve D, four-way valve A, four-way valve B;

[0057] Ambient temperature Tamb, passenger compartment set temperature Tset, compressor low-pressure side minimum operating temperature Ta, compressor low-pressure side maximum operating temperature Tb;

[0058] Electric drive and electric control water outlet temperature T3, electric drive and electric control minimum temperature T3m, electric drive and electric control upper limit temperature Td, electric drive and electric control water temperature difference ΔT3 (ΔT3=T3-T3m);

[0059] PTC outlet coolant temperature T4, PTC target temperature T4m, PTC temperature difference ΔT4 (ΔT4=T4-T4m);

[0060] Battery inlet temperature T5, battery outlet temperature T6, battery target water temperature Tbattery, battery temperature difference ΔT6 (ΔT6 = T6 - Tbattery);

[0061] Heater core surface temperature T7, heater core target temperature T7m, heater core temperature difference

[0062] ΔT7 (ΔT7 = T7 - ​​T7m);

[0063] Condenser outlet refrigerant temperature T, saturation temperature Te corresponding to P in PT2, superheat ΔSh (ΔSh = T-Te), target superheat ΔShm;

[0064] Compressor outlet temperature pressure PT1, compressor inlet temperature pressure PT2, pressure P of PT2, compressor target pressure Pm, pressure difference ΔP (ΔP=P-Pm). DETAILED DESCRIPTION

[0065] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0066] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] The present invention relates to a method for controlling an automobile thermal management heat pump, and mainly to a method for controlling a multi-source heat pump (electric drive source heat pump, electric drive waste heat + hot gas bypass, battery source heat pump, air source heat pump + PTC) in a system architecture diagram. Under the condition of constantly changing external conditions and customer vehicle use needs, how to use a control method to meet the wide low temperature (-40°C ~ 15°C) vehicle thermal management needs and the needs of cabin passengers, while achieving efficient recycling of energy and reducing the demand for battery power to increase the vehicle's cruising range.

[0068] PTC (Positive Temperature Coefficient), PTC heater is a new energy vehicle air conditioning component that uses the positive temperature coefficient characteristics of PTC materials for heating. When the PTC element is powered on, its resistance value will increase with the increase in temperature, so it will generate more heat to achieve the purpose of heating. PTC heaters have the advantages of fast heating speed, low energy consumption, and high safety, so they are widely used in new energy vehicles.

[0069] The present invention provides a multi-source heat pump control method, system and medium for thermal management of pure electric vehicles. The model is built through SIMULINK software, and the action of the electrical components is controlled according to this control method after being integrated with the whole vehicle model of the pure electric vehicle. The present invention avoids the above-mentioned problems through technical breakthroughs and innovations in control methods, parameter calibration, logic definition and valve matching, improves the cruising range, and tries to meet the thermal management requirements of the cabin, and ensures sufficient safety. Under different heat source modes, different multi-source heat pump control methods are selected, and the adaptability is high. A mode control method for a multi-source heat pump system for thermal management of a pure electric vehicle of the present invention optimizes the heat flow of the entire vehicle through an intelligent control strategy, realizes efficient recovery of electric drive heat and absorption of external environmental heat, reduces the demand for battery power, and improves the cruising range of the whole vehicle, and has a better mode selection strategy and control method, a wider temperature range adaptability and refrigerant adaptability. In addition, the compressor is in a suitable compression ratio state when operating at low temperature, which can improve the energy efficiency and life of the compressor.

[0070] The present invention provides a pure electric vehicle thermal management multi-source heat pump control method, comprising the following steps:

[0071] According to the heating or cooling requests issued by the passenger compartment and the battery, the corresponding multi-source heat pump control mode is selected in combination with the vehicle condition, vehicle speed and ambient temperature; the multi-source heat pump control mode includes electric drive source heat pump control mode, electric drive waste heat + hot gas bypass control mode, air source heat pump + PTC control mode, and battery source heat pump control mode.

[0072] Measure the surface temperature T7 of the heater core;

[0073] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and perform PI adjustment on the compressor speed according to the difference ΔT7;

[0074] For the high-temperature heating circuit, the opening of the three-way valve D is adjusted to meet the heating needs of the battery or the passenger compartment respectively;

[0075] For the low-temperature cooling circuit, according to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recovering the low-temperature heat in the air to meet the battery cooling needs.

[0076] It should be understood that the specific order or hierarchy of steps in the process disclosed by the present invention is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims provide the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0077] The present invention also provides a pure electric vehicle thermal management multi-source heat pump control system, comprising a multi-source heat pump selection module, a heater core temperature measurement module, a PI adjustment module, a high-temperature cooling module, and a low-temperature cooling module;

[0078] The multi-source heat pump selection module is used to select a corresponding multi-source heat pump control mode according to the heating or cooling request issued by the passenger compartment and the battery in combination with the vehicle condition, vehicle speed and ambient temperature;

[0079] The heater core temperature measurement module is used to measure the heater core surface temperature T7;

[0080] The PI adjustment module is used to calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and the compressor speed is PI-adjusted according to the difference ΔT7;

[0081] The high temperature cooling module is used for the high temperature heating circuit to meet the heating requirements of the battery or the passenger compartment respectively by adjusting the opening of the three-way valve D;

[0082] The low-temperature cooling module is used for the low-temperature cooling circuit. According to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recover the low-temperature heat in the air, and meet the battery cooling needs.

[0083] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps in the above-mentioned pure electric vehicle thermal management multi-source heat pump control method are implemented.

[0084] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0085] The present invention introduces in detail a method for controlling a mode of a multi-source heat pump (electric drive source heat pump, electric drive waste heat + hot gas bypass, battery source heat pump, air source heat pump + PTC) system for thermal management of a pure electric vehicle, which comprises a compressor 1, a plate-type water-cooled condenser 2, a first electronic expansion valve 3, a plate-type water-cooled evaporator 4, a second electronic expansion valve 17, a high-temperature electronic water pump 5, a PTC 6, a warm air core 7, a water-cooled evaporator 8, a blower 9, a battery 10, an expansion kettle 11, a low-temperature electronic water pump 12, a low-temperature radiator 13, an electronic fan 14, an electric drive electronic control 15, an expansion kettle 16, a four-way valve A, a four-way valve B, a three-way valve C, a three-way valve D, and a three-way valve E. Figure 1 , 3 The dark black line in 5 indicates that the circuit is connected, and the light gray line indicates that the circuit is disconnected.

[0086] Figure 1 This is the architecture diagram of the passenger compartment and battery heating at the same time of the present invention, which is applicable to the electric drive source heat pump control mode, the electric drive waste heat + hot air bypass control mode, and the air source heat pump + PTC control mode.

[0087] Refrigerant circuit: see Figure 1 In the middle black dotted line loop, the plate-type water-cooled evaporator 4 absorbs the waste heat of the electric drive and electronic control 15 on the coolant side through the low-temperature electronic water pump 12. The refrigerant side of the plate-type water-cooled evaporator 4 changes from low-temperature and low-pressure liquid to low-temperature and low-pressure gas, which is compressed by the compressor 1 and becomes high-temperature and high-pressure gas. The high-temperature heat is then transferred to the antifreeze liquid through the plate-type water-cooled condenser 2, and the refrigerant side becomes medium-temperature and high-pressure liquid. It is throttled by the first electronic expansion valve 3 and becomes low-temperature and low-pressure liquid, and returns to the plate-type water-cooled evaporator 4. When the waste heat of the electric drive is insufficient, the inlet temperature pressure PT2 of the compressor 1 will be too low. At this time, the second electronic expansion valve 17 needs to be opened to increase the pressure of PT2 to ensure the stable operation of the compressor.

[0088] Low temperature cooling circuit: see Figure 1 The left black dotted line loop circulates through the low-temperature electronic water pump 12 through the coolant side of the plate-type water-cooled evaporator 4, the four-way valve A (1-2), the three-way valve E (1-3), the electric drive and electronic control 15, the four-way valve B (1-2), and then to the low-temperature electronic water pump 12, transferring the heat of the electric drive and electronic control 15 to the plate-type water-cooled evaporator 4; when the electric drive and electronic control 15 has too much heat, the three-way valve E (2-3) is used to adjust the heat and transfer it to the low-temperature radiator 13, and then the electronic fan 14 discharges the heat to the air outside the vehicle.

[0089] High temperature heating circuit: see Figure 1The solid black line circuit on the right circulates through the high-temperature electronic water pump 5 through the coolant side of the plate-type water-cooled condenser 2, the three-way valve D (1-3), and / or the PTC 6, and transfers one path of heat to the heater core 7. The cold air exchanges heat with the heater core 7 through the blower 9 and transfers the heat to the passenger compartment to meet the heating demand of the passenger compartment; the other path of heat passes through the three-way valve D (1-2), the four-way valve A (3-4), and the three-way valve C (1-3) to transfer the heat to the battery for heating to meet the battery heating demand.

[0090] 1. Electric drive source heat pump control mode;

[0091] See Figure 1 , 2 As shown, the electric drive source heat pump control mode is suitable for driving conditions where both the passenger compartment and the battery make heating requests, the electric drive and electronic control water outlet temperature T3 is greater than -20°C, and the ambient temperature can be as low as -40°C.

[0092] The control method of the electric drive source heat pump control mode specifically includes the following steps:

[0093] Measure the surface temperature T7 of the heater core;

[0094] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and perform PI adjustment on the compressor speed according to the difference ΔT7;

[0095] For the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; the duty cycle of the three-way valve D (1-2) is 1-X1 to meet the battery heating requirement; the duty cycle of the three-way valve D (1-3) is X1 to meet the heating requirement of the passenger compartment;

[0096] For the low-temperature cooling circuit, the outlet water temperature T3 of the electric drive and electronic control is measured, and the opening of the three-way valve E and the switch of the electronic fan are controlled according to the outlet water temperature T3 of the electric drive and electronic control and the vehicle speed, so as to recover part of the heat of the electric drive and electronic control or discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, so that the temperature of the electric drive and electronic control reaches the target range value; the duty cycle of the three-way valve E (1-3) is X2, which is used to recover part of the heat of the electric drive and electronic control; the duty cycle of the three-way valve E (2-3) is 1-X2, and the opening and closing of the electronic fan are determined according to the vehicle speed and ambient temperature, so as to discharge the excess heat of the electric drive and electronic control to the outside of the vehicle.

[0097] Combination Figure 2When both the passenger compartment and the battery send out heating requests, the compressor performs PI (proportional-integral) dynamic adjustment according to the temperature difference ΔT7, and distributes the heat flow through proportional adjustment of the opening of the three-way valve D to meet the heating requirements of the passenger compartment and the battery under different vehicle conditions; the heat of the electric drive and electronic control 15 is reasonably distributed through the control of the three-way valve D and the electronic fan, and the cooling performance of the passenger compartment and battery heating is improved. The cooling performance coefficient = heating amount / electric power consumption, thereby extending the vehicle's cruising range.

[0098] The control method of compressor 1 is as follows: measuring the surface temperature T7 of the heater core, calculating the temperature difference ΔT7 between the surface temperature T7 of the heater core and the target temperature T7m, and dynamically adjusting the compressor speed by PI according to the temperature difference ΔT7. The compressor target speed = the current compressor speed + P + I, P = Kp*ΔT7, I = Ki*ΔT7; where P is the compressor speed change calculated by the proportional coefficient, in rpm; Kp is the proportional coefficient; I is the compressor speed change calculated by the integral coefficient, in rpm; Ki is the integral coefficient. The correspondence between the heater core target temperature T7m and the ambient temperature Tamb and the passenger compartment set temperature Tset can be obtained by calibrating the conversion function.

[0099] The control method of the first electronic expansion valve 3 is as follows: the superheat ΔSh is calculated by the measured value P of the compressor inlet temperature pressure PT2, and PI control is performed according to the target superheat ΔShm=5K; superheat ΔSh=T (condenser outlet refrigerant temperature)-Te (P value in PT2 corresponds to saturation temperature).

[0100] Control method of three-way valve D: By adjusting the opening of three-way valve D, the passenger compartment and battery heating can be satisfied at the same time. The battery is heated at different levels according to the inlet temperature T5. See Table 1 below for details.

[0101] Table 1

[0102]

[0103] The control method of the three-way valve E and the electronic fan: measure the outlet water temperature T3 of the electric drive and electronic control 15. When Ta<T3<Tb, the three-way valve E(1-3) is used to recover part of the heat of the electric drive and electronic control; Ta is the lowest operating temperature of the low-pressure side of the compressor, which is -10℃; Tb is the highest operating temperature of the low-pressure side of the compressor, which is 30℃. When T3>Tb, the electric drive and electronic control have too much heat. By adjusting the three-way valve E(2-3), the coolant passes through the low-temperature radiator 13 and the electronic fan 14 to discharge the excess heat to the air outside the vehicle. The control method is shown in Table 2. The low speed of the electronic fan in Table 2 refers to 1000rpm.

[0104] Table 2

[0105]

[0106]

[0107] 2. Electric drive waste heat + hot gas bypass control mode;

[0108] See Figure 3 As shown, the electric drive waste heat + hot gas bypass control mode is suitable for driving conditions where both the passenger compartment and the battery request heating. The electric drive and electronic control water outlet temperature T3 is less than -20°C, and the ambient temperature can be as low as -40°C.

[0109] The control method of the electric drive waste heat + hot gas bypass control mode specifically includes the following steps:

[0110] Measure the surface temperature T7 of the heater core;

[0111] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m. When the pressure P in the compressor inlet temperature pressure PT2 is ≥1.5bar, proceed to the next step. When the pressure P in the compressor inlet temperature pressure PT2 is <1.5bar, measure the pressure difference ΔP between the P value of the compressor inlet temperature pressure PT2 and the target pressure, perform PI dynamic adjustment through the second electronic expansion valve 17, replenish air to the compressor, and make the pressure P in the compressor inlet temperature pressure PT2 ≥1.5bar, and then proceed to the next step.

[0112] The compressor speed is PI-regulated according to the difference ΔT7;

[0113] For the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; the duty cycle of the three-way valve D (1-2) is 1-X1 to meet the battery heating requirement; the duty cycle of the three-way valve D (1-3) is X1 to meet the heating requirement of the passenger compartment;

[0114] For the low-temperature cooling circuit, the outlet water temperature T3 of the electric drive and electronic control is measured, and the difference ΔT3 between the outlet water temperature T3 of the electric drive and electronic control and the minimum temperature T3m of the electric drive and electronic control is calculated. The first electronic expansion valve 3 performs PI dynamic adjustment according to the difference ΔT3 to recover a small amount of heat from the electric drive and electronic control so that the temperature of the electric drive and electronic control reaches the target range value.

[0115] Combination Figure 3When both the passenger compartment and the battery send out heating requests, the compressor performs PI dynamic adjustment according to the temperature difference ΔT7, and distributes the heat flow through proportional adjustment of the three-way valve D to meet the heating requirements of the passenger compartment and the battery under different vehicle conditions; when the residual heat of the electric drive is insufficient, it is necessary to adjust the second electronic expansion valve 17 to replenish air to the compressor to increase the pressure of the compressor inlet temperature pressure PT2 to ensure stable operation of the compressor; by increasing the compression ratio by increasing the compressor speed, the power consumption heat is increased. In short, the compressor is regarded as a PTC, which absorbs a small amount of heat in the electric drive + most of the power consumption of the compressor itself, so as to meet the heating requirements of the passenger compartment and the battery.

[0116] Compressor 1 control mode: measure the surface temperature T7 of the heater core, calculate the temperature difference ΔT7 between the surface temperature T7 and the target temperature T7m, and perform PI dynamic adjustment on the compressor speed according to the temperature difference ΔT7. The compressor target speed = current compressor speed + P + I, P = Kp*ΔT7, I = Ki*ΔT7. The correspondence between the heater core target temperature T7m and the ambient temperature Tamb and the passenger compartment set temperature Tset can be obtained by calibrating the conversion function.

[0117] The control method of the first electronic expansion valve 3 is as follows: through the water temperature difference ΔT3 between the outlet water temperature T3 of the electric drive and electronic control 15 and the minimum temperature T3m (calibrated value) of the electric drive and electronic control, the first electronic expansion valve 3 performs PI dynamic adjustment according to the water temperature difference ΔT3 and through the low-temperature electronic water pump 12 and the plate-type water-cooled evaporator 4 to recover a small amount of heat from the electric drive and electronic control.

[0118] The control method of the second electronic expansion valve 17 is as follows: through the pressure difference ΔP between the pressure P value of the compressor inlet temperature pressure PT2 and the target pressure Pm, ΔP=P-Pm. The second electronic expansion valve 17 performs PI dynamic adjustment according to the pressure difference ΔP to replenish air to the compressor and increase the pressure of the compressor inlet temperature pressure PT2 to ensure stable operation of the compressor.

[0119] Control method of three-way valve D: By adjusting the duty cycle X1 of three-way valve D to simultaneously meet the heating of the passenger compartment and the battery, the battery is divided into heating levels according to the inlet temperature T5, which is the same as Table 1 above.

[0120] 3. Air source heat pump + PTC control mode;

[0121] See Figure 4 As shown, the air source heat pump + PTC control mode is applicable to the parking condition where both the passenger compartment and the battery make heating requests, the vehicle speed is 0 kmh, and the ambient temperature is -20℃~15℃.

[0122] The control method of the air source heat pump + PTC control mode specifically includes the following steps:

[0123] Measure the surface temperature T7 of the heater core;

[0124] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and the compressor speed is PI-regulated according to the difference ΔT7;

[0125] For the high-temperature heating circuit, first measure the coolant temperature T4 at the PTC outlet and compare it with its target temperature T4m; if T4 > T4m, proceed to the next step; if T4 < T4m, turn on the PTC, and the PTC is PI-dynamically regulated according to the difference ΔT4 between its outlet coolant temperature T4 and its target temperature T4m, and then proceed to the next step;

[0126] Secondly, measure the battery inlet temperature T5, and adjust the opening degree of the three-way valve D according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; the duty ratio of the three-way valve D (1-2) being on is 1-X1 to meet the battery heating requirement; the duty ratio of the three-way valve D (1-3) being on is X1 to meet the passenger compartment heating requirement;

[0127] For the low-temperature cooling circuit, measure the P value of the inlet temperature and pressure PT2 of the compressor 1, and adjust the gear of the electric fan according to the P value of PT2 to recover the low-temperature heat in the air.

[0128] Combined with Figure 4 , when both the passenger compartment and the battery send out heating requests, the compressor is PI-dynamically regulated according to the temperature difference ΔT7. The low-temperature cooling circuit absorbs the low-temperature heat of the external air through the electronic water pump, the low-temperature radiator circulation and the electric fan speed control in different gears; the coolant side of the water-cooled plate evaporator 4 absorbs the low-temperature heat, and the refrigerant side evaporates into a low-temperature and low-pressure gas and returns to the compressor, which is compressed into a high-temperature and high-pressure gas by the compressor; then the water-cooled condenser 2 is used to heat the passenger compartment and the battery. When the heating requirements of the passenger compartment and the battery are not enough, turn on the PTC6 to supplement the heat to meet the heating requirements of the passenger compartment and the battery under different ambient temperature conditions.

[0129] Control method of the compressor 1: Measure the surface temperature T7 of the heater core, calculate the temperature difference ΔT7 between the surface temperature T7 of the heater core and the target temperature T7m, and the compressor speed is PI-dynamically regulated according to the temperature difference ΔT7. The compressor target speed = compressor current speed + P + I, P = Kp * ΔT7, I = Ki * ΔT7. The corresponding relationship between the heater core target temperature T7m, the ambient temperature Tamb and the passenger compartment set temperature Tset can be obtained through a calibrated conversion function.

[0130] Control method of the first electronic expansion valve 3: Calculate the superheat ΔSh through the measured value of PT2, and perform PI control according to the target superheat ΔShm = 5K; the superheat ΔSh = T (refrigerant temperature at the condenser outlet) - Te (saturation temperature corresponding to P in PT2).

[0131] Electronic fan 14 control mode: the electronic fan gear is controlled according to the P value measured by PT2, and the control is shown in Table 3.

[0132] Table 3

[0133] P value of PT2 3bar≤P 1.8<P<3bar P≤1.8bar Fan position Low Range Mid-range upscale

[0134] Control method of three-way valve D: By adjusting the duty cycle X1 of three-way valve D to simultaneously meet the heating of passenger compartment and battery, the battery is divided into heating levels according to the inlet temperature T5, which is the same as Table 1 above.

[0135] PTC control mode: measure the PTC outlet coolant temperature T4, calculate the temperature difference ΔT4 between the PTC outlet coolant temperature and the target temperature T4m, and the PTC performs PI dynamic adjustment according to the temperature difference ΔT4. The adjustment range of the PTC under different ambient temperatures is shown in Table 4.

[0136] Table 4

[0137]

[0138] 4.Battery source heat pump control mode;

[0139] See Figure 5 , 6 As shown, the battery source heat pump control mode is suitable for driving conditions where the passenger compartment issues a heating request and the battery issues a cooling request, the vehicle speed is greater than 0 kmh, and the ambient temperature is 5°C to 15°C.

[0140] The control method of the battery source heat pump control mode specifically includes the following steps:

[0141] Measure the surface temperature of the heater core;

[0142] Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and perform PI adjustment on the compressor speed according to the difference ΔT7;

[0143] For the high-temperature heating circuit, the PTC outlet coolant temperature T4 is measured, and the difference ΔT4 between the PTC outlet coolant temperature T4 and its target temperature T4m is calculated. The opening of the three-way valve D is adjusted according to the size of the difference ΔT4 to meet the heating demand of the passenger compartment;

[0144] If ΔT4<3, adjust the duty cycle of the three-way valve D (1-2) to 0% and the duty cycle of (1-3) to 100%;

[0145] If 3≤ΔT4≤7, adjust the duty cycle of the three-way valve D(1-2) to 5%, and the duty cycle of (1-3) to 95%, and at the same time, the electric drive and electric control store heat for standby;

[0146] If 7<ΔT4<15, adjust the duty cycle of the three-way valve D(1-2) to 20%, and the duty cycle of (1-3) to 80%, and at the same time, the electric drive and electric control store heat for standby;

[0147] If ΔT4 ≥ 15, adjust the duty cycle of the three-way valve D (1-2) to 50%, and the duty cycle of (1-3) to 50%, and at the same time, the electric drive and electric control store heat for standby;

[0148] For the low-temperature cooling circuit, the battery outlet temperature T6 is measured, and the difference ΔT6 between the battery outlet temperature T6 and the target temperature T6m is calculated. The first electronic expansion valve 3 performs PI adjustment according to the difference ΔT6; the four-way valve A (2-3), the three-way valve C (1-3), and the four-way valve B (1-4) are adjusted respectively, and then pass through the low-temperature electronic water pump 12 to the water-cooled evaporator 4 to meet the battery cooling demand.

[0149] Refrigerant circuit: see Figure 5 In the middle black dotted line circuit, the plate-type water-cooled evaporator 4 absorbs the heat of the battery 10 on the coolant side through the low-temperature electronic water pump 12 circulation, and the refrigerant side of the plate-type water-cooled evaporator 4 changes from a low-temperature and low-pressure liquid to a low-temperature and low-pressure gas; after being compressed by the compressor 1, it becomes a high-temperature and high-pressure gas, and then the high-temperature heat is transferred to the antifreeze liquid through the plate-type water-cooled condenser 2, and the refrigerant side becomes a medium-temperature and high-pressure liquid, which is throttled by the first electronic expansion valve 3 to become a low-temperature and low-pressure liquid and returns to the plate-type evaporator 4.

[0150] Battery coolant circuit: see Figure 5 The middle black dotted line circuit circulates through the low-temperature electronic water pump 12 through the coolant side of the plate-type water-cooled evaporator 4, the four-way valve A (2-3), and the three-way valve C (1-3) to absorb the heat of the battery 10 to reduce the internal temperature of the battery 10; when the battery has too much heat, the heat is transferred to the electric drive and electronic control circuit for heat storage by adjusting the opening of the three-way valve D (1-2), the four-way valve A (1-4), and the three-way valve E (1-3).

[0151] High temperature heating circuit: see Figure 5 The solid black line circuit in the middle circulates through the high-temperature electronic water pump 5, passes through the coolant side of the plate-type water-cooled condenser 2, and the three-way valve D (1-3) to transfer heat to the heater core 7. The cold air exchanges heat with the heater core 7 through the blower 9 to transfer heat to the passenger compartment to meet the heating needs of the passenger compartment.

[0152] Combination Figure 6 When the passenger compartment issues a heating request and the battery issues a cooling request, the compressor performs PI dynamic adjustment according to the water temperature difference ΔT6. When giving priority to cooling the battery side, the heat flow is distributed through proportional adjustment of the three-way valve D to meet the heating needs of the passenger compartment at different set temperatures.

[0153] When T4m<T4<Td (T4m is the PTC target temperature, T4 is the PTC outlet coolant temperature, Td is the upper limit temperature of the electric drive and electric control, which is 65°C), the heat is transferred to the electric drive and electric control 15 for heat storage by adjusting the opening of the three-way valve D (1-2), the four-way valve A (1-4), and the three-way valve E (1-3). The control method of the three-way valve D is shown in Table 5 below.

[0154] Table 5

[0155]

[0156] Control method of compressor 1: PI dynamic adjustment is performed according to the difference ΔT6 between the battery target water temperature Tbattery and the battery outlet temperature T6, where ΔT6 = T6 - Tbattery.

[0157] The control method of the first electronic expansion valve 3 is as follows: the superheat ΔSh is calculated by measuring the P value of the compressor inlet temperature pressure PT2, and PI control is performed according to the target superheat ΔShm=5K; superheat ΔSh=T (condenser outlet refrigerant temperature)-Te (P in PT2 corresponds to the saturation temperature).

[0158] In summary, the mode control method and system of a multi-source heat pump system for thermal management of a pure electric vehicle of the present invention have the following advantages:

[0159] 1. Dynamic mode adjustment: When both the passenger compartment and the battery have heating requirements, the heat pump working mode can be dynamically adjusted according to the actual operating conditions of the vehicle (such as ambient temperature, battery status, electric drive temperature, passenger compartment air conditioning set temperature, internal and external circulation damper status, etc.) to achieve precise temperature control and improve overall energy efficiency. It can realize heating from multiple heat sources, including electric drive source heat pump, electric drive waste heat + hot air bypass, battery source heat pump, air source heat pump + PTC. It can realize timely selection of multiple heat sources according to the actual operating status of the vehicle, make full use of electric drive waste heat, and avoid energy waste.

[0160] 2. Wide temperature range working capability: In response to extreme climate conditions, the multi-source heat pump system can heat at -40℃, ensuring the endurance and comfort of electric vehicles in winter. It can work in the extremely low temperature range of -40℃, ensuring the endurance and comfort of electric vehicles in winter.

[0161] 3. Energy saving: The compressor speed is adjusted by setting the redundant target temperature of the passenger compartment to meet the heating needs of both the passenger compartment and the battery. The antifreeze flow is distributed to the passenger compartment and the battery by adjusting the ratio of the three-way water valve of the antifreeze circuit to avoid the situation where the compressor is not loaded after the passenger compartment and the battery meet the needs on one side, resulting in the other side not meeting the needs. When the residual heat of the electric drive is insufficient, the refrigerant hot gas bypass circuit is opened to avoid the problem of low energy efficiency caused by directly switching to the air source heat pump or PTC mode; when the battery has residual heat, the heat demand of the passenger compartment and the heat storage demand of the motor can be adjusted by the antifreeze flow to avoid direct dissipation to the environment and causing energy waste; in the air source heat pump + PTC mode, the electronic fan gear is controlled by the low pressure of the compressor, and the PTC power at different ambient temperatures is calibrated for different types of refrigerants, so that the compressor is in a better compression ratio state and the system energy efficiency is improved. The intelligent control strategy is used to make the compressor in a better compression ratio, improve the system energy efficiency, and extend the compressor service life.

[0162] 4. Applicability of the architecture diagram: Applicable to R134a, R1234yf, and R290 refrigerants.

[0163] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A multi-source heat pump control method for thermal management of pure electric vehicles, characterized in that: The following steps are included: According to the heating or cooling request from the passenger compartment and the battery, the corresponding multi-source heat pump control mode is selected in combination with the vehicle condition, vehicle speed and ambient temperature; Measure the surface temperature T7 of the heater core; Calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and perform PI adjustment on the compressor speed according to the difference ΔT7; For the high-temperature heating circuit, the opening of the three-way valve D is adjusted to meet the heating needs of the battery or the passenger compartment respectively; For the low-temperature cooling circuit, according to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recovering the low-temperature heat in the air to meet the battery cooling needs.

2. A pure electric vehicle thermal management multi-source heat pump control method according to claim 1, characterized in that: The multi-source heat pump control mode includes an electric drive source heat pump control mode, an electric drive waste heat + hot gas bypass control mode, an air source heat pump + PTC control mode, and a battery source heat pump control mode.

3. A pure electric vehicle thermal management multi-source heat pump control method according to claim 2, characterized in that: When the passenger compartment and the battery both send out heating requests, the electric drive and electric control water outlet temperature T3 is greater than -20°C, and the ambient temperature can be as low as -40°C. The electric drive source heat pump control mode is selected. The high temperature heating circuit and low temperature cooling circuit of the electric drive source heat pump control mode are as follows: For the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; For the low-temperature cooling circuit, the electric drive and electronic control water outlet temperature T3 is measured, and the opening of the three-way valve E and the switch of the electronic fan are controlled according to the electric drive and electronic control water outlet temperature T3 and the vehicle speed to recover part of the electric drive and electronic control heat or discharge excess heat of the electric drive and electronic control to the outside of the vehicle, so that the temperature of the electric drive and electronic control reaches the target range value.

4. A pure electric vehicle thermal management multi-source heat pump control method according to claim 2, characterized in that: When the passenger compartment and the battery both issue heating requests, the electric drive and electric control water outlet temperature T3 is less than -20°C, and the ambient temperature can be as low as -40°C. The electric drive waste heat + hot gas bypass control mode is selected. The high-temperature heating circuit and the low-temperature cooling circuit of the electric drive waste heat + hot gas bypass control mode are as follows: for the high-temperature heating circuit, the battery inlet temperature T5 is measured, and the opening of the three-way valve D is adjusted according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; For the low-temperature cooling circuit, the electric drive and electronic control water outlet temperature T3 is measured, and the difference ΔT3 between the electric drive and electronic control water outlet temperature T3 and the electric drive and electronic control minimum temperature T3m is calculated. The first electronic expansion valve performs PI dynamic adjustment according to the difference ΔT3 to recover a small amount of heat from the electric drive and electronic control so that the temperature of the electric drive and electronic control reaches the target range value.

5. A multi-source heat pump control method for thermal management of a pure electric vehicle according to claim 4, characterized in that: In the electric drive waste heat + hot gas bypass control mode, the compressor speed is adjusted according to the difference ΔT7 before the PI adjustment is performed. The following steps are included: When the compressor inlet temperature pressure PT2 has a pressure P ≥ 1.5 bar, the compressor speed is PI-regulated according to the difference ΔT7; When the pressure P in the compressor inlet temperature and pressure PT2 is less than 1.5 bar, the pressure difference ΔP between the measured P value of the compressor inlet temperature and pressure PT2 and the target pressure is measured, and PI dynamic adjustment is performed through the second electronic expansion valve to supply air to the compressor, so that the pressure P in the compressor inlet temperature and pressure PT2 is ≥ 1.5 bar, and then the compressor speed is PI adjusted according to the difference ΔT7.

6. A pure electric vehicle thermal management multi-source heat pump control method according to claim 2, characterized in that: In the parking condition where both the passenger compartment and the battery send heating requests, the vehicle speed is 0 km / h, and the ambient temperature is -20°C to 15°C, the air source heat pump + PTC control mode is selected. The high-temperature heating circuit and the low-temperature cooling circuit of the air source heat pump + PTC control mode are as follows: For the high-temperature heating circuit, measure the coolant temperature T4 at the PTC outlet and compare it with its target temperature T4m; if T4 > T4m, proceed to the next step; if T4 < T4m, turn on the PTC, and the PTC performs PI dynamic adjustment according to the difference ΔT4 between its outlet coolant temperature T4 and its target temperature T4m, and then proceed to the next step; Measure the battery inlet temperature T5, and adjust the opening of the three-way valve D according to the battery inlet temperature T5 and the vehicle condition to meet the heating requirements of the battery and the passenger compartment respectively; For the low-temperature cooling circuit, measure the P value of the compressor inlet temperature and pressure PT2, and adjust the gear of the electric fan according to the P value of PT2 to recover the low-temperature heat in the air.

7. A pure electric vehicle thermal management multi-source heat pump control method according to claim 2, characterized in that: In the driving condition where the passenger compartment sends a heating request and the battery sends a cooling request, the vehicle speed is greater than 0 km / h, and the ambient temperature is 5°C to 15°C, the battery source heat pump control mode is selected. The high-temperature heating circuit and the low-temperature cooling circuit of the battery source heat pump control mode are as follows: For the high-temperature heating circuit, measure the coolant temperature T4 at the PTC outlet, calculate the difference ΔT4 between the coolant temperature T4 at the PTC outlet and its target temperature T4m, and adjust the opening of the three-way valve D according to the magnitude of the difference ΔT4 to meet the heating requirements of the passenger compartment; For the low-temperature cooling circuit, measure the battery outlet temperature T6, calculate the difference ΔT6 between the battery outlet temperature T6 and the target temperature T6m, and the first electronic expansion valve performs PI adjustment according to the difference ΔT6; adjust the four-way valve A, the three-way valve C, and the four-way valve B respectively, and then pass through the low-temperature electric water pump to the water-cooled evaporator to meet the battery cooling requirements.

8. A pure electric vehicle thermal management multi-source heat pump control method according to claim 7, characterized in that: In the battery source heat pump control mode, if ΔT4 ≥ 3, adjust the three-way valve D to reserve the electric drive and electronic control heat storage, specifically as follows: If 3 ≤ ΔT4 ≤ 7, adjust the three-way valve D with a duty ratio of 5% for the (1-2) connection and 95% for the (1-3) connection, and at the same time reserve the electric drive and electronic control heat storage; If 7 < ΔT4 < 15, adjust the three-way valve D with a duty ratio of 20% for the (1-2) connection and 80% for the (1-3) connection, and at the same time reserve the electric drive and electronic control heat storage; If ΔT4 ≥ 15, adjust the three-way valve D with a duty ratio of 50% for the (1-2) connection and 50% for the (1-3) connection, and at the same time reserve the electric drive and electronic control heat storage.

9. A multi-source heat pump control system for thermal management of pure electric vehicles, characterized in that: It includes a multi-source heat pump selection module, a warm air core temperature measurement module, a PI adjustment module, a high-temperature cooling module, and a low-temperature cooling module; The multi-source heat pump selection module is used to select a corresponding multi-source heat pump control mode according to the heating or cooling request issued by the passenger compartment and the battery in combination with the vehicle condition, vehicle speed and ambient temperature; The heater core temperature measurement module is used to measure the heater core surface temperature T7; The PI adjustment module is used to calculate the difference ΔT7 between the surface temperature T7 of the heater core and its target temperature T7m, and the compressor speed is PI-adjusted according to the difference ΔT7; The high temperature cooling module is used for the high temperature heating circuit to meet the heating requirements of the battery or the passenger compartment respectively by adjusting the opening of the three-way valve D; The low-temperature cooling module is used for the low-temperature cooling circuit. According to different multi-source heat pump control modes, it is used to recover part of the heat of the electric drive and electronic control and discharge the excess heat of the electric drive and electronic control to the outside of the vehicle, recover the low-temperature heat in the air, and meet the battery cooling needs.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps in a pure electric vehicle thermal management multi-source heat pump control method according to any one of claims 1 to 8 are implemented.

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