Control method for thermal management system

Abstract

The invention relates to a control method for a thermal management system, and belongs to the technical field of vehicle thermal management. According to the first scheme, only a cab refrigeration mode is started, and when the temperature of the output side of an evaporator is smaller than a first set temperature and the pressure of the input side of a compressor is smaller than set pressure, the rotating speed of the compressor is reduced to the minimum; when the temperature of the output side of the evaporator continues to be reduced to the second set temperature, a battery refrigeration mode is started to consume redundant cooling capacity; when the temperature of the output side of the evaporator is increased to a third set temperature, the battery refrigeration mode is closed; according to the second scheme, the cab refrigeration mode and the battery refrigeration mode are started at the same time, and when the temperature of the output side of the evaporator is smaller than the fourth set temperature, the opening degree of the first expansion valve is adjusted to be smaller, and the opening degree of the second expansion valve is adjusted to be larger; and when the output side temperature of the evaporator continues to be reduced to the critical frosting temperature, the rotating speed of the compressor is reduced. The comfort of the cab air conditioner is improved by preventing the evaporator from frosting.

Description

Technical Field

[0001] The invention relates to a control method for a thermal management system, belonging to the technical field of vehicle thermal management. Background Art

[0002] At present, the vehicle thermal management system of pure electric heavy-duty trucks is mostly a direct evaporative air-conditioning system for the cab air-conditioning and a water plate exchange system for the battery thermal management system. This solution requires two compressors and two independent air-conditioning systems, which has the disadvantages of low system integration, low component utilization, and high cost. At the same time, because the air-conditioning system and the battery thermal management system are independent of each other and cannot distribute cooling capacity, the comfort of the air-conditioning and the high cooling capacity demand of the battery cannot be met at the same time.

[0003] When the existing vehicle thermal management system only turns on the cab cooling mode, in spring and autumn or when the temperature is not high, the cab will not require much cooling, so it will open the 1 / 2 low windshield (usually there are 7 windshields). At this time, the evaporator of the air-conditioning refrigeration cycle will often be frosted, causing the compressor to start and stop constantly, causing great damage to the compressor. At the same time, the air output of the air conditioner is sometimes cool and sometimes natural wind, making the air conditioning very comfortable.

[0004] The existing vehicle thermal management system's air conditioning refrigeration cycle in the cab cooling mode and the battery refrigeration cycle in the battery cooling mode share a compressor. Therefore, when the cab cooling mode and the battery cooling mode are turned on at the same time, in spring and autumn or when the temperature is not high, the cab requires little cooling and 1 / 2 windshield is opened. At this time, evaporator frost often occurs. Due to the evaporator frost, the compressor starts and stops continuously, and the compressor cannot run at a high frequency, resulting in the inability to meet the cooling capacity required for battery water cooling, which leads to high battery temperature. At the same time, the air outlet of the air conditioner is sometimes cool and sometimes natural wind, making the air conditioning very comfortable. Summary of the invention

[0005] The object of the present invention is to provide a control method for a thermal management system to solve the problem of poor comfort of air conditioning.

[0006] To achieve the above object, the solution of the present invention includes: A control method for a thermal management system of the present invention includes at least one of the following solutions: Solution 1: When only the cab cooling mode is turned on, the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air conditioning refrigeration cycle is lower than the first set temperature, and the input side pressure of the compressor in the air conditioning refrigeration cycle is lower than the set pressure, the speed of the compressor is reduced to the minimum. If the output side temperature of the evaporator continues to drop to the second set temperature, the battery cooling mode is turned on. If the output side temperature of the evaporator rises to the third set temperature, the battery cooling mode is turned off. The third set temperature is greater than or equal to the first set temperature. Solution 2: When the cab cooling mode and the battery cooling mode are turned on at the same time, and the output side temperature of the evaporator is lower than the fourth set temperature, the opening of the first expansion valve in series with the evaporator in the air conditioning refrigeration cycle is reduced, and the opening of the second expansion valve is increased. If the output side temperature of the evaporator continues to drop to the critical frosting temperature, the speed of the compressor is reduced; The battery refrigeration cycle in the battery refrigeration mode includes a second expansion valve and a compressor.

[0007] Furthermore, in the case where only the cab cooling mode is turned on, on the basis of turning on the battery cooling mode, the opening of the first expansion valve is reduced, and the opening of the second expansion valve is increased.

[0008] Furthermore, after adjusting the openings of the first expansion valve and the second expansion valve, if the output side temperature of the evaporator rises to the third set temperature, the opening of the first expansion valve is restored to the initial state on the basis of turning off the battery cooling mode.

[0009] Furthermore, the first set temperature ranges from 5 to 8 degrees Celsius, the set pressure ranges from 0.25 to 0.26 MPa, the second set temperature ranges from 1 to 3 degrees Celsius, and the third set temperature ranges from 8 to 10 degrees Celsius.

[0010] Furthermore, the fourth set temperature ranges from 6 to 9 degrees Celsius, and the critical frosting temperature ranges from 0 to 2 degrees Celsius.

[0011] Furthermore, in the second solution, after the speed of the compressor is reduced, if the output side temperature of the evaporator rises back to the fifth set temperature, the speed of the compressor is increased.

[0012] Furthermore, the fifth set temperature ranges from 4 to 6 degrees Celsius.

[0013] Furthermore, in the second solution, after the compressor speed is increased, if the output side temperature of the evaporator continues to rise to the sixth set temperature, the openings of the first expansion valve and the second expansion valve are adjusted to the initial state.

[0014] Furthermore, the sixth set temperature ranges from 8 to 10 degrees Celsius.

[0015] Furthermore, the air conditioning refrigeration cycle and the battery refrigeration cycle also share a condenser; the output side temperature of the evaporator is collected by a temperature sensor arranged on the output side of the evaporator; the input side pressure of the compressor is collected by a pressure sensor arranged on the input side of the compressor.

[0016] Beneficial effects of the present invention: The present invention is a pioneering invention, which provides a control method for a thermal management system, specifically including at least one of the following schemes, scheme one: when the thermal management system only turns on the cab cooling mode, in spring and autumn or when the temperature is not high, since the cab does not require much cooling, the 1 / 2 gear will be opened to block the wind, and the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air-conditioning refrigeration cycle and the input side pressure of the compressor in the cycle are monitored. When the output side temperature of the evaporator is lower than the first set temperature and the input side pressure of the compressor is lower than the set pressure, the speed of the compressor is reduced to the minimum speed, and the evaporator in the air-conditioning refrigeration cycle is avoided from frosting by reducing the generation of cooling; when the output side temperature of the evaporator continues to drop to the second set temperature, the battery cooling mode is turned on, and excess cooling is consumed by battery cooling to avoid frosting of the evaporator in the air-conditioning refrigeration cycle; when the output side temperature of the evaporator rises to the third set temperature, the battery cooling mode is turned off to meet the cooling demand of the cab.

[0017] Solution 2: When the thermal management system turns on the cab cooling mode and the battery cooling mode at the same time, in spring and autumn or when the temperature is not high, since the cab does not require much cooling, it will open 1 / 2 gear to block the wind, monitor the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air-conditioning refrigeration cycle, and when the output side temperature of the evaporator is lower than the fourth set temperature, reduce the opening of the first expansion valve in series with the evaporator in the air-conditioning refrigeration cycle, and increase the opening of the second expansion valve of the battery refrigeration cycle in the battery cooling mode, and immediately tilt the cooling capacity from the air-conditioning side to the battery water-cooling side, so as to consume a large proportion of cooling capacity through the battery to avoid frosting of the evaporator in the air-conditioning refrigeration cycle; if the output side temperature of the evaporator continues to drop to the critical frosting temperature, the evaporator in the air-conditioning refrigeration cycle is avoided by reducing the speed of the compressor.

[0018] The present invention mainly avoids the compressor from constantly starting and stopping by preventing the evaporator from frosting, and the air conditioning air is sometimes cold and sometimes natural, thereby ultimately achieving the purpose of improving the comfort of the air conditioning. Among them, the air conditioning refrigeration cycle and the battery refrigeration cycle share a compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a control flow chart for thermal management system; Figure 2It is a schematic diagram of the thermal management system. DETAILED DESCRIPTION

[0020] To solve the problems in the background technology, the present invention mainly avoids frosting of the evaporator by reducing the speed of the compressor or consuming cold energy through battery refrigeration, so as to improve the comfort of the cab air conditioning.

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0022] Embodiment 1 of a control method for a thermal management system: A control method for a thermal management system comprises the following steps: When the thermal management system only turns on the cab cooling mode, the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air conditioning refrigeration cycle of the thermal management system is less than the first set temperature, and the input side pressure of the compressor in the air conditioning refrigeration cycle is less than the set pressure, the speed of the compressor is reduced to the minimum, and the generation rate of cold energy is reduced to the minimum to reduce the generation of cold energy to avoid frosting of the evaporator; if the output side temperature of the evaporator continues to drop to the second set temperature, the battery cooling mode is turned on to consume excess cold energy, thereby avoiding frosting of the evaporator; if the output side temperature of the evaporator rises to the third set temperature, the battery cooling mode is turned off so that the generated cold energy can meet the cooling demand of the cab. Among them, the battery refrigeration cycle in the battery refrigeration mode and the air conditioning refrigeration cycle in the cab refrigeration mode share a compressor; the third set temperature is greater than or equal to the first set temperature.

[0023] The present invention improves the comfort of the cab air conditioning mainly by avoiding frosting of the evaporator; while avoiding frosting of the evaporator, the generated cooling capacity meets the cooling capacity demand of the cab, thereby improving the comfort of the cab air conditioning.

[0024] Specifically, after the battery cooling mode is turned on, the superheat of the two expansion valves is adjusted by controlling the opening of the first expansion valve and the second expansion valve to allocate the proportion of the cooling capacity in the cab (inside the vehicle) and the cooling capacity of the battery. The specific adjustment can be made according to the demand. If the total cooling capacity is large, the cab consumes too little, and the battery cooling capacity demand is too large, the opening of the second expansion valve in the battery refrigeration cycle in the battery cooling mode can be increased, and the opening of the first expansion valve in the air-conditioning refrigeration cycle connected in series with the evaporator can be reduced to achieve on-demand distribution of cooling capacity; if the total cooling capacity is large, the cab consumption is average, and the battery cooling capacity demand is too large, only the opening of the second expansion valve in the battery refrigeration cycle in the battery cooling mode can be appropriately increased, and the opening of the first expansion valve in the air-conditioning refrigeration cycle connected in series with the evaporator can be kept unchanged to achieve on-demand distribution of cooling capacity.

[0025] Specifically, after adjusting the openings of the first expansion valve and the second expansion valve, if the output side temperature of the evaporator rises to the third set temperature, the opening of the first expansion valve is restored to the initial state on the basis of turning off the battery cooling mode.

[0026] Specifically, if only the opening degree of the second expansion valve is adjusted, then after the opening degree of the second expansion valve is adjusted, if the output side temperature of the evaporator rises to the third set temperature, only the battery cooling mode may be turned off.

[0027] Among them, the first set temperature is greater than the second set temperature, and the third set temperature is greater than or equal to the first set temperature. The specific values ​​can be set according to actual needs. Specifically, the value range of the first set temperature is 5 to 8 degrees Celsius, the value range of the set pressure is 0.25 to 0.26 MPa, the value range of the second set temperature is 1 to 3 degrees Celsius, and the value range of the third set temperature is 8 to 10 degrees Celsius. Taking values ​​within this value range can control the thermal management system more accurately and efficiently, and effectively improve the comfort of the cab air conditioning.

[0028] Specifically, the air conditioning refrigeration cycle and the battery refrigeration cycle of the thermal management system used in the control method share a common compressor and a common condenser, thereby improving the integration of the thermal management system. The output side temperature of the evaporator is acquired by a temperature sensor disposed on the output side of the evaporator. The input side pressure of the compressor is acquired by a pressure sensor disposed on the input side of the compressor.

[0029] Embodiment 2 of a control method for a thermal management system: A control method for a thermal management system comprises the following steps: When the thermal management system turns on the cab cooling mode and the battery cooling mode at the same time, and the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air conditioning refrigeration cycle of the thermal management system is less than the fourth set temperature, the opening of the first expansion valve in the air conditioning refrigeration cycle connected in series with the evaporator is reduced, and the opening of the second expansion valve in the battery refrigeration cycle in the battery refrigeration mode is increased, and the cooling capacity is immediately tilted from the air conditioning side to the battery water cooling side, and the battery consumes a large proportion of cooling capacity to avoid frosting of the evaporator in the air conditioning refrigeration cycle; if the output side temperature of the evaporator continues to drop to the critical frosting temperature, the evaporator is prevented from frosting by reducing the speed of the compressor. Among them, the battery refrigeration cycle in the battery refrigeration mode and the air conditioning refrigeration cycle in the cab refrigeration mode share a compressor.

[0030] The present invention improves the comfort of the cab air conditioner by avoiding frost on the evaporator. The fourth set temperature is greater than the critical frost temperature. The specific value of the fourth set temperature can be set according to actual needs, and the critical frost temperature depends on the specifications of the evaporator. Specifically, the value range of the fourth set temperature is 6 to 9 degrees Celsius, and the value range of the critical frost temperature is generally 0 to 2 degrees Celsius. By taking a value within this value range, the thermal management system can be controlled more accurately and efficiently, effectively improving the comfort of the cab air conditioner.

[0031] Specifically, after reducing the compressor speed, if the output side temperature of the evaporator returns to the fifth set temperature, the compressor speed is increased to make the compressor run at a high frequency, which can avoid frosting of the evaporator while meeting the cooling needs of the vehicle and the battery at the same time.

[0032] The fifth set temperature is greater than the critical frosting temperature, and its specific value can be set according to actual needs. Specifically, the fifth set temperature has a value range of 4 to 6 degrees Celsius. Taking a value within this value range can control the thermal management system more accurately and efficiently.

[0033] Specifically, after increasing the compressor speed, if the output side temperature of the evaporator continues to rise to the sixth set temperature, the opening of the first expansion valve and the second expansion valve is adjusted to the initial state, so that the cooling demand of the vehicle and the battery can be met at the same time while avoiding frosting of the evaporator. Among them, the sixth set temperature is greater than the fifth set temperature, and its specific value can be set according to actual needs. Specifically, the value range of the sixth set temperature is 8 to 10 degrees Celsius. Taking a value within this value range can control the thermal management system more accurately and efficiently.

[0034] Specifically, the air conditioning refrigeration cycle and the battery refrigeration cycle of the thermal management system used in the control method share a common compressor and a common condenser, thereby improving the integration of the thermal management system. The output side temperature of the evaporator is acquired by a temperature sensor disposed on the output side of the evaporator. The input side pressure of the compressor is acquired by a pressure sensor disposed on the input side of the compressor.

[0035] Embodiment 3 of a control method for a thermal management system: A control method for a thermal management system, such as Figure 1 As shown, there are two solutions: Solution 1: When the thermal management system only turns on the cab cooling mode, in spring and autumn or when the temperature is not high, since the cab does not require much cooling, it will open 1 / 2 gear to block the wind, monitor the output side temperature of the evaporator used for heat exchange with the car in the air-conditioning refrigeration cycle and the input side pressure of the compressor in the cycle, and when the output side temperature of the evaporator is lower than the first set temperature and the input side pressure of the compressor is lower than the set pressure, reduce the speed of the compressor to the minimum speed to avoid frosting of the evaporator by reducing the generation of cooling; when the output side temperature of the evaporator continues to drop to the second set temperature, turn on the battery cooling mode, consume excess cooling by battery cooling, so as to avoid frosting of the evaporator; when the output side temperature of the evaporator rises to the third set temperature, turn off the battery cooling mode to meet the cooling demand of the cab. The present invention mainly avoids the constant starting and stopping of the compressor and the alternation of cool and natural air from the air conditioner by avoiding the frosting of the evaporator in the air conditioning refrigeration cycle, thereby ultimately achieving the purpose of improving the comfort of the air conditioning; while avoiding the frosting of the evaporator, the generated cooling capacity can meet the cooling capacity demand of the cab, thereby improving the comfort of the air conditioning in the cab.

[0036] Solution 2: When the thermal management system turns on the cab cooling mode and the battery cooling mode at the same time, in spring and autumn or when the temperature is not high, since the cab does not require much cooling, it will open 1 / 2 gear to block the wind, monitor the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air conditioning refrigeration cycle, and when the output side temperature of the evaporator is lower than the fourth set temperature, reduce the opening of the first expansion valve in series with the evaporator in the air conditioning refrigeration cycle, and increase the opening of the second expansion valve of the battery refrigeration cycle in the battery refrigeration mode, and immediately tilt the cooling capacity from the air conditioning side to the battery water cooling side, and consume a large proportion of cooling capacity through battery refrigeration to avoid evaporator frosting; if the output side temperature of the evaporator continues to drop to the critical frosting temperature, the evaporator frosting is avoided by reducing the speed of the compressor. Among them, the air conditioning refrigeration cycle and the battery refrigeration cycle share a compressor.

[0037] Specifically, after reducing the speed of the compressor, when the temperature on the output side of the evaporator returns to the fifth set temperature, the speed of the compressor is increased to make the compressor run at a high frequency, so that the cooling demand of the vehicle and the battery can be met at the same time while avoiding frosting of the evaporator. Specifically, after increasing the speed of the compressor, when the temperature on the output side of the evaporator continues to rise to the sixth set temperature, the opening of the first expansion valve and the second expansion valve are adjusted to the initial state, so that the cooling demand of the vehicle and the battery can be met at the same time while avoiding frosting of the evaporator. The present invention increases the speed of the compressor while avoiding frosting of the evaporator, so that the compressor runs at a high frequency, which can meet the cooling required for battery water cooling and effectively avoid high temperature of the battery.

[0038] by Figure 2 Taking the thermal management system shown in the figure as an example, the control method for the thermal management system of the present invention is described in detail, as follows: The vehicle thermal management system can simultaneously meet the requirements of cab air conditioning refrigeration and battery heat dissipation, and its main components include: a compressor, a condenser, and a cooling fan ( Figure 2 Fan in the middle), electronic expansion valve EXV1, evaporator, blower, electronic expansion valve EXV2, plate heat exchanger (referred to as plate heat exchanger), water pump, battery pack heat exchanger ( Figure 2 Referred to as battery pack in Chinese), high-pressure pressure sensor ( Figure 2 P is high pressure and low pressure sensor ( Figure 2 P low pressure) and temperature sensors at different locations. Figure 2 As shown, the temperature sensors include T exhaust, T outdoor, T in, T inlet pipe 1, T inlet pipe 2, T outlet pipe 1, T outlet pipe 2, T return water, and T outlet water. P high pressure is used to collect the pressure on the compressor output side, P low pressure is used to collect the pressure on the compressor input side, T inlet pipe 1 is used to collect the temperature on the evaporator input side, T inlet pipe 2 is used to collect the temperature on the heat exchanger input side, T outlet pipe 1 is used to collect the temperature on the evaporator output side, and T outlet pipe 2 collects the temperature on the heat exchanger input side.

[0039] Among them, the air-conditioning refrigeration cycle includes a compressor, a condenser, EXV1 and an evaporator connected in sequence, and the evaporator is used to exchange heat with the interior of the vehicle; the battery refrigeration cycle includes a compressor, a condenser, EXV2 and the refrigerant side of a plate heat exchanger connected in sequence, the refrigerant side of the plate heat exchanger exchanges heat with its liquid-cooled side, and the liquid-cooled side of the plate heat exchanger is connected in series in the battery liquid cooling cycle, and the battery liquid cooling cycle includes a water pump connected in series, the liquid-cooled side of the plate heat exchanger and the battery pack heat exchanger.

[0040] Taking into account the cooling of the single-open cab, in spring and autumn or when the temperature is not high, the demand for cooling is not large, and the 1 / 2 low windshield will be opened (usually there are 7 windshields). At this time, the evaporator will often be frosted, causing the compressor to start and stop constantly, causing great damage to the compressor. At the same time, the air output of the air conditioner is sometimes cold and sometimes natural wind, which is very uncomfortable. The present invention is controlled as follows: when the temperature of the T outlet pipe 1, i.e., the output side of the evaporator, is lower than the T set temperature value 1 (i.e., the first set temperature, whose value range is 5-8°C) and the P low pressure, i.e., the pressure on the output side of the compressor, is lower than the P set pressure (i.e., the set pressure, whose value range is 0.25-0.26Mpa), the compressor is immediately reduced to the lowest speed; when the T outlet pipe 1 continues to decrease to the T set temperature value 2 (i.e., the second set temperature, whose value range is 1-3°C), the battery water circuit refrigeration is turned on (specifically, the water pump and the electronic expansion valve EXV2 are turned on) to distribute the cold capacity, and at the same time, the superheat of EXV1 (i.e., the first expansion valve) and EXV2 (i.e., the second expansion valve) is adjusted; when the T outlet pipe 1 is heated to the T set temperature value 3 (i.e., the third set temperature, whose value range is 8-10°C), the battery water circuit refrigeration (water pump and electronic expansion valve EXV2) is turned off, and the opening of EXV1 and EXV2 is restored to the initial state, so as to ensure that the air-conditioning side is always in a refrigeration state, and the cold wind is constant, thereby improving the comfort of the air-conditioning.

[0041] Taking into account the cab cooling and battery water cooling at the same time, in spring and autumn or when the temperature is not high, the cab requires less cooling, and 1 / 2 windshield is opened. At this time, the evaporator will often be frosted. The compressor cannot run at a high frequency due to the evaporator frosting, resulting in the inability to meet the cooling required by the battery water cooling, which leads to high battery temperature. The control of the present invention is as follows: when the T outlet pipe 1 is lower than the T set temperature value 4 (i.e., the fourth set temperature, whose value range is 6-9°C), the opening of EXV1 is adjusted to be smaller, the opening of EXV2 is adjusted to be larger, the superheat 1 of EXV1 is increased, and the superheat 2 of EXV2 is reduced, and the cooling capacity is immediately tilted from the air conditioning side to the battery water cooling side; when the T outlet pipe 1 continues to cool down to the critical frosting point T set temperature value (i.e., the critical frosting temperature, whose value range is 0-2°C), the compressor starts to reduce the frequency at this time to reduce the compressor When the temperature of T outlet pipe 1 rises to a value slightly higher than the critical frost point T set temperature value 5 (i.e., the fifth set temperature, whose value range is 4-6°C), the compressor starts to perform frequency up-conversion processing, increases the speed of the compressor, and when T outlet pipe 1 continues to heat up to T set temperature value 6 (i.e., the sixth set temperature, whose value range is 8-10°C), the opening of EXV1 and EXV2 is restored to the initial state; this can simultaneously meet the needs of cab air conditioning and battery water cooling, and avoid high battery temperatures caused by evaporator frosting. The opening of the electronic expansion valve is controlled according to the superheat of the evaporator and the plate exchanger, and the cooling capacity distribution is adjusted according to different working conditions, and the coordination capacity is adjusted to improve the comfort of the cab air conditioning and ensure the heat dissipation effect of the battery. Among them, the electronic expansion valve is EXV, which is controlled by the superheat, and the corresponding superheat = T outlet pipe-T inlet pipe; the smaller the opening of the expansion valve, the greater its superheat.

[0042] The present invention provides a control logic for the case where a single air conditioner evaporator is frosted, and a control logic for the case where both the air conditioner and the battery water-cooled evaporator are frosted. The control logic for the case where both the air conditioner and the battery water-cooled evaporator are frosted reduces the refrigerant flow in the evaporator by first reducing the opening of the first expansion valve, and simultaneously increases the opening of the second expansion valve to increase the refrigerant flow in the plate exchanger, and then reduces the total cooling capacity by reducing the compressor speed, and consumes a large proportion of cooling capacity on the battery side, thereby reducing the battery temperature and eliminating cooling capacity waste. The present invention ensures that the air conditioner side is always in a constant cold air cooling state, thereby improving the comfort of air conditioner use.

Claims

1. A control method for a thermal management system, characterized in that: Includes at least one of the following: Solution 1: When only the cab cooling mode is turned on, the output side temperature of the evaporator used for heat exchange with the interior of the vehicle in the air conditioning refrigeration cycle is lower than the first set temperature, and the input side pressure of the compressor in the air conditioning refrigeration cycle is lower than the set pressure, the speed of the compressor is reduced to the minimum, if the output side temperature of the evaporator continues to drop to the second set temperature, the battery cooling mode is turned on, if the output side temperature of the evaporator rises to the third set temperature, the battery cooling mode is turned off; the third set temperature is greater than or equal to the first set temperature; Solution 2: When the cab cooling mode and the battery cooling mode are turned on at the same time, and the output side temperature of the evaporator is lower than the fourth set temperature, the opening of the first expansion valve in the air conditioning refrigeration cycle circuit connected in series with the evaporator is reduced, and the opening of the second expansion valve is increased. If the output side temperature of the evaporator continues to decrease to the critical frosting temperature, the speed of the compressor is reduced; The battery refrigeration cycle in the battery refrigeration mode includes the second expansion valve and the compressor.

2. The control method for a thermal management system according to claim 1, characterized in that: In the cab cooling mode only, on the basis of turning on the battery cooling mode, the opening of the first expansion valve is reduced and the opening of the second expansion valve is increased.

3. The control method for a thermal management system according to claim 2, characterized in that: After adjusting the openings of the first expansion valve and the second expansion valve, if the output side temperature of the evaporator rises to the third set temperature, the opening of the first expansion valve is restored to the initial state on the basis of turning off the battery cooling mode.

4. The control method for a thermal management system according to any one of claims 1 to 3, characterized in that: The first set temperature ranges from 5 to 8 degrees Celsius, the set pressure ranges from 0.25 to 0.26 MPa, the second set temperature ranges from 1 to 3 degrees Celsius, and the third set temperature ranges from 8 to 10 degrees Celsius.

5. The control method for a thermal management system according to claim 1, characterized in that: The fourth set temperature ranges from 6 to 9 degrees Celsius, and the critical frosting temperature ranges from 0 to 2 degrees Celsius.

6. The control method for a thermal management system according to claim 1 or 5, characterized in that: In the second solution, after reducing the speed of the compressor, if the output side temperature of the evaporator rises back to the fifth set temperature, the speed of the compressor is increased.

7. The control method for a thermal management system according to claim 6, characterized in that: The fifth set temperature ranges from 4 to 6 degrees Celsius.

8. The control method for a thermal management system according to claim 6, characterized in that: In the second solution, after the compressor speed is increased, if the output side temperature of the evaporator continues to rise to the sixth set temperature, the openings of the first expansion valve and the second expansion valve are adjusted to the initial state.

9. The control method for a thermal management system according to claim 8, characterized in that: The sixth set temperature ranges from 8 to 10 degrees Celsius.

10. The control method for a thermal management system according to claim 1, characterized in that: The air conditioning refrigeration cycle and the battery refrigeration cycle also share a condenser; the output side temperature of the evaporator is collected by a temperature sensor arranged on the output side of the evaporator; the input side pressure of the compressor is collected by a pressure sensor arranged on the input side of the compressor.

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