Control method for multi-evaporator type thermal management system, thermal management system, and vehicle

Abstract

The invention discloses a control method of a multi-evaporator type heat management system, the heat management system and a vehicle, and relates to the technical field of new energy automobile heat management systems and control methods thereof. If yes, a driving side refrigerant circulation path is switched into a running state, the opening degree of a driving side expansion valve is gradually increased till the calibrated minimum refrigerating capacity Qmin is equal to the thermal management requirement of the cab side, the temperature of the battery pack is monitored in real time, and if the temperature of the battery pack is lower than a preset low-temperature protection threshold value, temperature protection treatment is conducted on the battery pack; the invention mainly solves the problem of how to provide a reasonable control method for the multi-evaporator type thermal management system. The reasonable control method is provided for the multi-evaporator type heat management system under the scene that the requirement for the refrigerating capacity is low, and the reliability and stability of the heat management system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of a thermal management system for a new energy vehicle and a control method thereof, and in particular to a control method for a multi-evaporator thermal management system, a thermal management system and a vehicle. Background Art

[0002] New energy vehicles that use electric motors as one of their driving forces are gradually gaining market share.

[0003] The thermal management system of new energy vehicles is quite different from that of traditional vehicles. For example, in addition to meeting the temperature control requirements of the cab, the thermal management system of new energy vehicles also needs to meet the temperature control requirements of electric drive devices such as battery packs, motors and controllers. Therefore, the thermal management system of new energy vehicles usually needs to be equipped with at least two evaporators to meet the temperature control requirements of the above-mentioned different temperature zones (i.e., the cab and electric drive devices).

[0004] During the operation of the multi-evaporator thermal management system, the speed range of the compressor is limited (for example, the variable frequency compressor needs to set a minimum speed to meet the oil return demand of the lubricating oil and maintain the normal operation of the thermal management system). In the scenario where the overall heat generation of the new energy vehicle is low (for example, the cab needs to be cooled, and the electric drive device does not need phase change cooling), the cooling capacity corresponding to the minimum speed of the compressor will far exceed the overall cooling capacity demand of the new energy vehicle, which will cause problems such as overshoot of the thermal management system; in addition, the compressor runs at the lowest speed for a long time, which can easily cause problems such as difficulty in returning the lubricating oil, excessive temperature of the variable frequency drive, and low energy efficiency of the thermal management system.

[0005] In summary, how to provide a reasonable control method for the multi-evaporator thermal management system in the scenario of low cooling capacity demand has become an urgent problem to be solved. Summary of the invention

[0006] The object of the present invention is to provide a control method, a thermal management system and a vehicle for a multi-evaporator type thermal management system, which can obtain a reasonable control method in a scenario with low cooling capacity demand, thereby improving the reliability and stability of the thermal management system while meeting the cooling capacity demand and energy consumption control.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a control method of a multi-evaporator type thermal management system, which can be applied in a thermal management system; a refrigeration module of the thermal management system at least includes a compressor, a condenser, a cab-side expansion valve, a cab-side evaporator, a drive-side expansion valve and a drive-side evaporator; the compressor, the condenser, the cab-side expansion valve and the cab-side evaporator are circulated and connected in sequence to form a cab-side refrigerant circulation path; the compressor, the condenser, the drive-side expansion valve and the drive-side evaporator are circulated and connected in sequence to form a drive-side refrigerant circulation path;

[0008] The method includes:

[0009] S1. Divide the compressor into several groups of working conditions. Under each group of working conditions, measure the lowest speed at which the compressor can maintain normal operation, which is recorded as the calibrated lowest speed n. min , and the compressor is measured at the lowest calibrated speed n min The corresponding cooling capacity is recorded as the minimum cooling capacity Q min ;

[0010] S2, under each group of working conditions, the compressor is rotated from the calibrated minimum speed n min Start to increase the speed, and divide the speed of the compressor into several gear speeds n 1,2,…,n , respectively record the speed n of the compressor at each gear 1,2,…,n The cooling capacity under the gear is recorded as the gear cooling capacity Q 1,2,…,n ;

[0011] S3, record the minimum calibrated speed n measured by the compressor under each set of working conditions min , rated minimum cooling capacity Q min , gear speed n 1,2,…,n And the gear cooling capacity Q 1,2,…,n , forming a reference data model of cooling capacity;

[0012] S4. During the operation of the vehicle, according to the thermal management requirements of the vehicle, controlling the speed of the compressor, the opening of the cab-side expansion valve, and the opening of the drive-side expansion valve;

[0013] S5, real-time monitoring of the operating conditions and the speed of the compressor, under any operating condition, if the speed of the compressor reaches the calibrated minimum speed n min , then obtain the corresponding calibrated minimum cooling capacity Q in the cooling capacity reference data model min , and there are:

[0014] S5.a, if only the refrigerant circulation path on the cab side is in operation, and the calibrated minimum cooling capacity Q min When the cooling capacity is greater than the heat management demand of the cab side, the drive side refrigerant circulation path is switched to the running state, and the opening of the drive side expansion valve is gradually increased until the calibrated minimum cooling capacity Q min The thermal management requirements are equal to those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than a preset low temperature protection threshold, the battery pack is subjected to temperature protection processing;

[0015] S5.b, if only the drive side refrigerant circulation path is in operation, and the calibrated minimum cooling capacity Q min When the temperature is greater than the thermal management requirement of the driving side, the battery pack is subjected to temperature protection treatment;

[0016] S6. Under any operating condition, if the speed of the compressor reaches the calibrated minimum speed n min , and when the temperature of the variable frequency drive of the compressor exceeds the preset warning threshold, the gear speed n recorded by the cooling capacity reference data model is 1,2,…,n , gradually increase the speed of the compressor until the temperature of the variable frequency drive is below the warning threshold, and obtain the gear speed n in the cooling capacity reference data model 1,2,…,n The corresponding gear cooling capacity Q 1,2,…,n , and there are:

[0017] S6.a, if only the cab side refrigerant circulation path is in operation, and the gear cooling capacity Q 1,2,…,n When the cooling capacity Q is greater than the heat management demand of the cab side, the drive side refrigerant circulation path is switched to the running state, and the opening of the drive side expansion valve is gradually increased until the gear cooling capacity Q 1,2,…,n The thermal management requirements are equal to those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than a preset low temperature protection threshold, the battery pack is subjected to temperature protection processing;

[0018] S6.b, if only the drive side refrigerant circulation path is in operation, and the gear cooling capacity Q 1,2,…,n When the temperature is greater than the thermal management requirement of the driving side, the battery pack is subjected to temperature protection treatment.

[0019] In the above technical solution, in step S5.a, the battery pack is subjected to temperature protection treatment, specifically:

[0020] (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than a preset low temperature protection threshold;

[0021] (2) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, then the low-temperature radiator is used to recover heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0022] (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0023] In the above technical solution, in step S5.b, the battery pack is subjected to temperature protection treatment, specifically:

[0024] (1) If the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than a preset low-temperature protection threshold;

[0025] (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S5.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0026] In the above technical solution, in step S6.a, the battery pack is subjected to temperature protection treatment, specifically:

[0027] (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than a preset low temperature protection threshold;

[0028] (2) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, then the low-temperature radiator is used to recover heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0029] (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0030] In the above technical solution, in step S6.b, the battery pack is subjected to temperature protection treatment, specifically:

[0031] (1) If the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than a preset low-temperature protection threshold;

[0032] (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S6.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0033] In the above technical solution, in step S2, the speed of the compressor is divided into a number of gear speeds n 1,2,…,n The specific method is: under each group of working conditions, the compressor is calibrated from the lowest speed n min Start to increase the speed, measure the relationship between the refrigeration capacity and energy efficiency value of the compressor and the speed, and divide the speed of the compressor into several gear speeds n according to the level of the energy efficiency value. 1,2,…,n .

[0034] In the above technical solution, the operating conditions include any one or more of the following: ambient temperature, the evaporation temperature of the compressor, and the condensation temperature of the compressor.

[0035] In the above technical solution, in step S4, the thermal management requirements of the vehicle include any one or more of the following: a given air outlet temperature of the air conditioner in the cab, a given air outlet gear of the air conditioner in the cab, the temperature of the battery pack, the temperature of the motor and the temperature of the drive controller.

[0036] A thermal management system applies the control method of the multi-evaporator thermal management system.

[0037] A vehicle comprises the above thermal management system.

[0038] Compared with the prior art, the present invention has the following advantages: the control method, thermal management system and vehicle of the multi-evaporator thermal management system of the present invention can calibrate the minimum cooling capacity Q minWhen the heat management demand on the cab side is greater than that on the cab side, the refrigerant circulation path on the drive side is switched to the running state, and the minimum cooling capacity Q can be calibrated. min When the temperature is greater than the thermal management demand of the drive side, the battery pack is subjected to temperature protection treatment. In this way, a reasonable control method is provided for the multi-evaporator thermal management system in the scenario of low cooling capacity demand, thereby improving the reliability and stability of the thermal management system while meeting the cooling capacity demand and energy consumption control, and effectively avoiding the problem of the compressor running at the lowest speed for a long time, thereby increasing the service life of the thermal management system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural view of the thermal management system of the present invention.

[0040] The accompanying drawings are marked as follows: 1. compressor; 2. condenser; 3. expansion valve on the cab side; 4. evaporator on the cab side; 5. expansion valve on the driving side; 6. evaporator on the driving side; 7. first circulation pump; 8. second circulation pump; 9. four-way valve; 10. low-temperature radiator; 11. liquid heat exchanger; 12. third circulation pump; 13. heater; 14. three-way valve; 15. air heat exchanger; 100. battery pack; 200. motor; 300. drive control device. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present embodiment provides a control method for a multi-evaporator thermal management system, which can be applied in the thermal management system to control the operation of the thermal management system to avoid problems such as overshoot in the thermal management system.

[0043] The thermal management system of this embodiment is installed on a vehicle that uses an electric motor as (one of) the driving forces, and its thermal management objects include a battery pack 100, a motor 200, a drive control device 300 (for example, a three-in-one controller) and an air conditioner in the cab; wherein the battery pack 100, the motor 200 and the drive control device 300 are all equipped with a liquid cooling medium channel for heat exchange with the liquid cooling medium.

[0044] See also Figure 1 As a typical case, the thermal management system of this embodiment includes at least a refrigeration module, and the refrigeration module of the thermal management system includes at least a compressor 1, a condenser 2, a cab side expansion valve 3, a cab side evaporator 4, a drive side expansion valve 5 and a drive side evaporator 6.

[0045] Among them, the compressor 1 is a compressor used to compress refrigerant in the refrigeration system, specifically a variable frequency compressor; the condenser 2 is a condenser in the refrigeration system, which dissipates heat through its own fan, and the fan is a precision electronic fan that can control and feedback its rotation speed; the cab side expansion valve 3 and the drive side expansion valve 5 are both throttling devices in the refrigeration system. In this embodiment, the cab side expansion valve 3 and the drive side expansion valve 5 are both electronic expansion valves; the cab side evaporator 4 and the drive side evaporator 6 are both evaporators in the refrigeration system, which can provide refrigerant for evaporation, thereby cooling.

[0046] The compressor 1, the condenser 2, the cab-side expansion valve 3 and the cab-side evaporator 4 are circulated and connected in sequence to form a cab-side refrigerant circulation path; the compressor 1, the condenser 2, the drive-side expansion valve 5 and the drive-side evaporator 6 are circulated and connected in sequence to form a drive-side refrigerant circulation path; the refrigeration module shares the compressor 1 and the condenser 2, which is also a common setting of the vehicle's thermal management system. The output end of the condenser 2 is diverted to the cab-side expansion valve 3 and the drive-side expansion valve 5, and the output end of the cab-side evaporator 4 and the output end of the drive-side evaporator 6 are converged to the input end of the compressor 1.

[0047] The thermal management system of this embodiment further includes a liquid cooling module, which includes at least a first circulation pump 7 , a second circulation pump 8 , a four-way valve 9 , a low-temperature radiator 10 and a liquid heat exchanger 11 .

[0048] Among them, the first circulation pump 7 and the second circulation pump 8 are both liquid pumps capable of driving the flow of liquid cooling medium, such as electronic water pumps; the four-way valve 9 is a liquid valve, which has a port a, a port b, a port c and a port d that can be controlled by a host computer (such as a vehicle controller or a thermal management system controller) to open, close and switch the connection; the low-temperature radiator 10 is a metal radiator with multiple liquid flow channels, and heat dissipation fins are arranged between each liquid flow channel. It can dissipate heat for the liquid cooling medium flowing through it by forced convection or natural convection. In this embodiment, the low-temperature radiator 10 and the condenser 2 of the refrigeration module share one / a group of fans. In other embodiments, the condenser 2 of the refrigeration module and the low-temperature radiator 10 of the liquid cooling module can also be configured with an independent group of fans; the liquid heat exchanger 11 has two independent liquid flow channels, which can provide heat exchange for the medium in the two liquid flow channels;

[0049] like Figure 1As shown, when the port a and the port b of the four-way valve 9 are interconnected, and the port c and the port d are interconnected, one liquid-cooling medium circulation path is: the first circulation pump 7, the port a and the port b of the four-way valve 9, the liquid-cooling medium channel of the driving side evaporator 6, the liquid heat exchanger 11 and the liquid-cooling medium channel of the battery pack 100, and the liquid-cooling medium circulation path realizes phase change refrigeration and heat dissipation through the driving side evaporator 6; the other liquid-cooling medium circulation path is: the second circulation pump 8, the port c and the port d of the four-way valve 9, the liquid-cooling medium channel of the drive control device 300, the liquid-cooling medium channel of the motor 200 and the low-temperature radiator 10, and the liquid-cooling medium circulation path realizes air convection heat dissipation through the low-temperature radiator 10.

[0050] When port a and port d of the four-way valve 9 are interconnected, and port b and port c are interconnected, the liquid cooling medium circulation path is: the first circulation pump 7, port a and port d of the four-way valve 9, the liquid cooling medium channel of the drive control device 300, the liquid cooling medium channel of the motor 200, the low-temperature radiator 10, the second circulation pump 8, port c and port b of the four-way valve 9, the liquid cooling medium channel of the drive side evaporator 6, the liquid heat exchanger 11 and the liquid cooling medium channel of the battery pack 100. The liquid cooling medium circulation path realizes air convection heat dissipation through the low-temperature radiator 10. At this time, the refrigeration module is not operating.

[0051] The thermal management system of this embodiment further includes a heating module, which includes at least a third circulation pump 12 , a heater 13 , a three-way valve 14 and an air heat exchanger 15 .

[0052] Among them, the third circulation pumps 12 are all liquid pumps that can drive the flow of liquid cooling medium, such as electronic water pumps; the heater 13 is an electric liquid heater 13, which is used to heat the liquid cooling medium, and it can be controlled by the host computer to open / close and adjust the heating power; the three-way valve 14 is a liquid valve, which has a port a, a port b and a port c that can be controlled by the host computer (such as a vehicle controller or a thermal management system controller) to open, close, and switch the connection; the air heat exchanger 15 is a metal heat exchanger with multiple liquid flow channels, and heat dissipation fins are arranged between each liquid flow channel. It can dissipate the heat of the liquid cooling medium flowing through it into the air by forced convection.

[0053] like Figure 1As shown, the a port and the b port of the three-way valve 14 are interconnected. When the c port is closed, the liquid cooling medium circulation path is: the third circulation pump 12, the heater 13, the a port and the b port of the three-way valve 14 and the air heat exchanger 15. In the liquid cooling medium circulation path, the liquid cooling medium is heated by the heater 13 and is emitted into the cab when flowing through the air heat exchanger 15 to provide air conditioning warm air for the cab; the a port and the c port of the three-way valve 14 are interconnected. When the b port is closed, the liquid cooling medium circulation path is : The third circulation pump 12, the heater 13, the a port and the c port of the three-way valve 14 and the liquid heat exchanger 11 of the liquid cooling module. In the liquid cooling medium circulation path, the liquid cooling medium is heated by the heater 13. When flowing through the liquid heat exchanger 11, it can heat the liquid cooling medium in the liquid cooling module, thereby heating / insulating the battery pack 100; obviously, when the a port, the b port and the c port of the three-way valve 14 are interconnected, it can provide air conditioning warm air for the cab and heat / insulate the battery pack 100.

[0054] The thermal management system of this embodiment is only used as a typical case. For example, in other embodiments, the driving side evaporator 6 can be a direct cooling heat exchanger. For example, in other embodiments, liquid cooling modules and heating modules of other structures can be used. In fact, it is only necessary to configure a refrigeration module with a compressor 1, a condenser 2, a cab side expansion valve 3, a cab side evaporator 4, a driving side expansion valve 5 and a driving side evaporator 6 to implement the following control method.

[0055] The control method of the multi-evaporator thermal management system of this embodiment includes:

[0056] S1. Divide the compressor into several groups of working conditions. Under each group of working conditions, measure the lowest speed at which the compressor can maintain normal operation, which is recorded as the calibrated minimum speed n. min , and measured the compressor at the lowest calibrated speed n min The corresponding cooling capacity is recorded as the minimum cooling capacity Q min .

[0057] The operating conditions include any one or more of the following: ambient temperature, evaporation temperature of the compressor, and condensation temperature of the compressor.

[0058] The compressor is divided into several groups of working conditions, specifically, the ambient temperature, the evaporation temperature of the compressor and the condensation temperature of the compressor are divided into several groups within a certain range, any one or several of which are formed to form several groups of working conditions, and the compressors are placed in the several groups of working conditions respectively / sequentially; for example, the ambient temperature is divided into -20℃~0℃, 0℃~20℃ and 20℃~40℃, and the compressors are placed in the ambient temperatures respectively / sequentially.

[0059] In this embodiment, the compressor can maintain the lowest speed for normal operation (i.e., the calibrated lowest speed n min ), specifically, the lowest speed at which the compressor can meet the oil return volume requirement under this operating condition.

[0060] S2, under each group of working conditions, the compressor is rotated from the rated minimum speed n min Start to increase the speed and divide the compressor speed into several gear speeds n 1,2,…,n , respectively record the compressor speed n at each gear 1,2,…,n The cooling capacity under the gear is recorded as the gear cooling capacity Q 1,2,…,n .

[0061] Specifically, in step S2, the speed of the compressor is divided into a number of gear speeds n 1,2,…,n , the specific method is:

[0062] Under each group of working conditions, the compressor is rotated from the rated minimum speed n min Start to increase the speed, measure the relationship between the compressor's cooling capacity and energy efficiency value and the speed, and divide the compressor speed into several gear speeds n according to the level of energy efficiency value. 1,2,…,n .

[0063] Among them, the level of energy efficiency value is a range value, which can be defined by national standards, industry standards, industry regulations and other scientific standards / scientific regulations, or it can be defined by the manufacturer itself.

[0064] Among them, gear speed n 1,2,…,n Specifically, it refers to the midpoint value of the speed of the compressor at a certain energy efficiency level, and the gear cooling capacity Q 1,2,…,n Specifically, the compressor speed n at a certain gear 1,2,…,n The cooling capacity below.

[0065] S3. Record the lowest rated speed n measured by the compressor under each set of working conditions. min , rated minimum cooling capacity Q min , gear speed n 1,2,…,n And the gear cooling capacity Q 1,2,…,n , forming a reference data model for cooling capacity.

[0066] In some possible embodiments, the minimum speed n is calibrated min As the starting point of the independent variable, the gear speed n 1,2,…,n As a discrete independent variable, the minimum cooling capacity Q min As the starting point of the dependent variable, and the calibrated minimum speed n min Correspondingly, the cooling capacity Q 1,2,…,n As a discrete dependent variable, it is respectively related to the speed n of each gear1,2,…,n Correspondingly, a refrigeration capacity reference data model can be obtained, and the refrigeration capacity reference data model will be reflected in a data form.

[0067] S4. During the operation of the vehicle, the speed of the compressor, the opening of the expansion valve on the cab side, and the opening of the expansion valve on the driving side are controlled according to the thermal management requirements of the vehicle.

[0068] Specifically, the thermal management requirements of the vehicle include any one or more of the following: a given air outlet temperature of the air conditioner in the cab, a given air outlet position of the air conditioner in the cab, the temperature of the battery pack, the temperature of the motor, and the temperature of the drive controller.

[0069] In this step, the rotation speed of the compressor, the opening of the cab-side expansion valve, and the opening of the drive-side expansion valve are controlled, which is specifically achieved through a vehicle controller or a thermal management system controller.

[0070] S5. Real-time monitoring of the compressor working conditions and compressor speed. Under any working condition, if the compressor speed reaches the calibrated minimum speed n min , then obtain the corresponding calibrated minimum cooling capacity Q in the cooling capacity reference data model min , and there are:

[0071] S5.a, if only the refrigerant circulation path on the cab side is in operation and the minimum cooling capacity Q is calibrated min When the cooling capacity is greater than the heat management demand on the cab side, the refrigerant circulation path on the driving side is switched to the running state, and the opening of the expansion valve on the driving side is gradually increased until the minimum cooling capacity Q is calibrated. min The thermal management requirements are the same as those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than the preset low-temperature protection threshold, the battery pack is subjected to temperature protection treatment.

[0072] The above will calibrate the minimum cooling capacity Q min The minimum cooling capacity Q can be compared by converting the cab temperature, ambient temperature, cab air conditioning set air outlet temperature, cab air conditioning set air outlet position, etc. into the same thermodynamic unit. min Thermal management requirements on the cab side.

[0073] The above, the minimum cooling capacity Q min When the pressure is greater than the thermal management demand on the cab side, the air conditioner in the cab is prone to overshoot (perceived as excessive cooling capacity). At this time, the refrigerant circulation path on the driving side is switched to the running state. The refrigerant circulation path on the driving side will divert part of the refrigerant on the refrigerant circulation path on the cab side, and by gradually increasing the opening of the expansion valve on the driving side, the refrigerant flow on the refrigerant circulation path on the cab side can be indirectly adjusted until the minimum cooling capacity Q is calibrated.min When it is equal to the thermal management demand on the cab side, overshoot of the cab air conditioning can be avoided.

[0074] S5.b, if only the drive side refrigerant circulation path is in operation and the minimum cooling capacity Q is calibrated min When it is greater than the thermal management requirement of the drive side, the battery pack is subjected to temperature protection.

[0075] S6. Under any operating condition, if the compressor speed reaches the rated minimum speed n min , and the temperature of the compressor's variable frequency drive exceeds the preset warning threshold (e.g. 0.9 times the frequency reduction temperature), the gear speed n recorded according to the cooling capacity reference data model is 1,2,…,n , increase the speed of the compressor step by step until the temperature of the variable frequency drive is below the warning threshold, and obtain the speed n of this gear in the cooling capacity reference data model 1,2,…,n The corresponding gear cooling capacity Q 1,2,…,n , and there are:

[0076] S6.a, if only the refrigerant circulation path on the cab side is in operation and the gear cooling capacity Q 1,2,…,n When the cooling capacity is greater than the heat management demand on the cab side, the refrigerant circulation path on the driving side is switched to the running state, and the opening of the expansion valve on the driving side is gradually increased until the gear cooling capacity Q 1,2,…,n The thermal management requirements are the same as those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than the preset low-temperature protection threshold, the battery pack is subjected to temperature protection treatment.

[0077] As mentioned above, the gear cooling capacity Q 1,2,…,n The heat management requirements of the cab side (such as cab temperature, ambient temperature, cab air conditioning given air outlet temperature and cab air conditioning given air outlet gear, etc.) are converted into the same thermodynamic unit, and the gear cooling capacity Q can be compared. 1,2,…,n Thermal management requirements on the cab side.

[0078] The above mentioned gear cooling capacity Q 1,2,…,n When the pressure is greater than the heat management demand on the cab side, the air conditioner in the cab is prone to overshoot (perceived as excessive cooling capacity). At this time, the refrigerant circulation path on the driving side is switched to the running state. The refrigerant circulation path on the driving side will divert part of the refrigerant on the refrigerant circulation path on the cab side, and by gradually increasing the opening of the expansion valve on the driving side, the refrigerant flow on the refrigerant circulation path on the cab side can be indirectly adjusted until the gear cooling capacity Q 1,2,…,n When it is equal to the thermal management demand on the cab side, overshoot of the cab air conditioning can be avoided.

[0079] S6.b, if only the drive side refrigerant circulation path is in operation, and the gear cooling capacity Q 1,2,…,n When it is greater than the thermal management requirement of the drive side, the battery pack is subjected to temperature protection.

[0080] Specifically, in step S5.a, the battery pack is subjected to temperature protection processing, specifically:

[0081] (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than the preset low temperature protection threshold;

[0082] (2) If the cooling module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0083] (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0084] Specifically, in step S5.b, the battery pack is subjected to temperature protection processing, specifically:

[0085] (1) If the thermal management system is equipped with a low-temperature radiator, the low-temperature radiator recovers heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0086] (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S5.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0087] Specifically, in step S6.a, the battery pack is subjected to temperature protection processing, specifically:

[0088] (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than the preset low temperature protection threshold;

[0089] (2) If the cooling module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0090] (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0091] Specifically, in step S6.b, the battery pack is subjected to temperature protection processing, specifically:

[0092] (1) If the thermal management system is equipped with a low-temperature radiator, the low-temperature radiator recovers heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold;

[0093] (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S6.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

[0094] The control method, thermal management system and vehicle of the multi-evaporator thermal management system of the present embodiment can calibrate the minimum cooling capacity Q min When the heat management demand on the cab side is greater than that on the cab side, the refrigerant circulation path on the drive side is switched to the running state, and the minimum cooling capacity Q can be calibrated. min When the temperature is greater than the thermal management demand of the drive side, the battery pack is subjected to temperature protection treatment. In this way, a reasonable control method is provided for the multi-evaporator thermal management system in the scenario of low cooling capacity demand, thereby improving the reliability and stability of the thermal management system while meeting the cooling capacity demand and energy consumption control, and effectively avoiding the problem of the compressor running at the lowest speed for a long time, thereby increasing the service life of the thermal management system.

[0095] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control method for a multi-evaporator thermal management system, which can be applied in the thermal management system; The refrigeration module of the thermal management system at least includes a compressor, a condenser, a cab side expansion valve, a cab side evaporator, a drive side expansion valve and a drive side evaporator; The compressor, the condenser, the cab-side expansion valve and the cab-side evaporator are circulated and connected in sequence to form a cab-side refrigerant circulation path; the compressor, the condenser, the drive-side expansion valve and the drive-side evaporator are circulated and connected in sequence to form a drive-side refrigerant circulation path; It is characterized in that The method includes: S1. Divide the compressor into several groups of working conditions. Under each group of working conditions, measure the lowest speed at which the compressor can maintain normal operation, which is recorded as the calibrated lowest speed n. min , and the compressor is measured at the lowest calibrated speed n min The corresponding cooling capacity is recorded as the minimum cooling capacity Q min ; S2, under each group of working conditions, the compressor is rotated from the calibrated minimum speed n min Start to increase the speed, and divide the speed of the compressor into several gear speeds n 1,2,…,n , respectively record the speed n of the compressor at each gear 1,2,…,n The cooling capacity under the gear is recorded as the gear cooling capacity Q 1,2,…,n ; S3, record the minimum calibrated speed n measured by the compressor under each set of working conditions min , rated minimum cooling capacity Q min , gear speed n 1,2,…,n And the gear cooling capacity Q 1,2,…,n , forming a reference data model of cooling capacity; S4. During the operation of the vehicle, according to the thermal management requirements of the vehicle, controlling the speed of the compressor, the opening of the cab-side expansion valve, and the opening of the drive-side expansion valve; S5, real-time monitoring of the operating conditions and the speed of the compressor, under any operating condition, if the speed of the compressor reaches the calibrated minimum speed n min , then obtain the corresponding calibrated minimum cooling capacity Q in the cooling capacity reference data model min , and there are: S5.a, if only the refrigerant circulation path on the cab side is in operation, and the calibrated minimum cooling capacity Q min When the cooling capacity is greater than the heat management demand of the cab side, the drive side refrigerant circulation path is switched to the running state, and the opening of the drive side expansion valve is gradually increased until the calibrated minimum cooling capacity Q min The thermal management requirements are equal to those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than a preset low temperature protection threshold, the battery pack is subjected to temperature protection processing; S5.b, if only the drive side refrigerant circulation path is in operation, and the calibrated minimum cooling capacity Q min When the temperature is greater than the thermal management requirement of the driving side, the battery pack is subjected to temperature protection treatment; S6. Under any operating condition, if the speed of the compressor reaches the calibrated minimum speed Q min , and when the temperature of the variable frequency drive of the compressor exceeds the preset warning threshold, the gear speed n recorded by the cooling capacity reference data model is 1,2,…,n , gradually increase the speed of the compressor until the temperature of the variable frequency drive is below the warning threshold, and obtain the gear speed n in the cooling capacity reference data model 1,2,…,n The corresponding gear cooling capacity Q 1,2,…,n , and there are: S6.a, if only the cab side refrigerant circulation path is in operation, and the gear cooling capacity Q 1,2,…,n When the cooling capacity Q is greater than the heat management demand of the cab side, the drive side refrigerant circulation path is switched to the running state, and the opening of the drive side expansion valve is gradually increased until the gear cooling capacity Q 1,2,…,n The thermal management requirements are equal to those on the cab side. At the same time, the temperature of the battery pack is monitored in real time. If the temperature of the battery pack is lower than a preset low temperature protection threshold, the battery pack is subjected to temperature protection processing; S6.b, if only the drive side refrigerant circulation path is in operation, and the gear cooling capacity Q 1,2,…,n When the temperature is greater than the thermal management requirement of the driving side, the battery pack is subjected to temperature protection treatment.

2. The control method of the multi-evaporator thermal management system according to claim 1, characterized in that: In step S5.a, the battery pack is subjected to temperature protection treatment, specifically: (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than a preset low temperature protection threshold; (2) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, then the low-temperature radiator is used to recover heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold; (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S5.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

3. The control method of a multi-evaporator thermal management system according to claim 1 or 2, characterized in that: In step S5.b, the battery pack is subjected to temperature protection treatment, specifically: (1) If the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than a preset low-temperature protection threshold; (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S5.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

4. The control method of a multi-evaporator thermal management system according to claim 1, characterized in that: In step S6.a, the battery pack is subjected to temperature protection processing, specifically: (1) If the refrigeration module of the thermal management system is equipped with a gas-liquid separator, the refrigerant is guided into the gas-liquid separator until the temperature of the battery pack is higher than a preset low temperature protection threshold; (2) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator, or after implementing part (1) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, but the thermal management system is equipped with a low-temperature radiator, then the low-temperature radiator is used to recover heat from the air side to the battery pack until the temperature of the battery pack is higher than the preset low-temperature protection threshold; (3) If the refrigeration module of the thermal management system is not equipped with a gas-liquid separator and the thermal management system is not equipped with a low-temperature radiator, or, after implementing part (2) of step S6.a, the temperature of the battery pack is still lower than the preset low-temperature protection threshold, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

5. The control method of a multi-evaporator thermal management system according to claim 1 or 4, characterized in that: In step S6.b, the battery pack is subjected to temperature protection, specifically: (1) If the thermal management system is equipped with a low-temperature radiator, heat is recovered from the air side of the battery pack through the low-temperature radiator until the temperature of the battery pack is higher than a preset low-temperature protection threshold; (2) If the thermal management system is not equipped with a low-temperature radiator, or if the temperature of the battery pack is still lower than the preset low-temperature protection threshold after implementing part (1) of step S6.b, the battery pack is heated by a heater until the temperature of the battery pack is higher than the preset low-temperature protection threshold.

6. The control method of a multi-evaporator thermal management system according to claim 1, characterized in that: In step S2, the speed of the compressor is divided into a number of gear speeds n 1,2,…,n , the specific method is: Under each group of working conditions, the compressor is rotated from the calibrated minimum speed n min Start to increase the speed, measure the relationship between the refrigeration capacity and energy efficiency value of the compressor and the speed, and divide the speed of the compressor into several gear speeds n according to the level of the energy efficiency value. 1,2,…,n .

7. The control method of a multi-evaporator thermal management system according to claim 1, characterized in that: The operating conditions include any one or more of the following: Ambient temperature, the evaporating temperature of the compressor, and the condensing temperature of the compressor.

8. The control method of a multi-evaporator thermal management system according to claim 1, characterized in that: In step S4, the thermal management requirements of the vehicle include any one or more of the following: The air outlet temperature of the air conditioner in the cab, the air outlet position of the air conditioner in the cab, the temperature of the battery pack, the temperature of the motor and the temperature of the drive controller.

9. A thermal management system, characterized in that: A control method for a multi-evaporator thermal management system using any one of claims 1-8.

10. A vehicle, characterized in that: Includes the thermal management system as claimed in claim 9.

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