HVAC system of vehicle and control method thereof

Abstract

The invention relates to an HVAC system of a vehicle and a control method thereof. The system includes a compressor having a compression portion, a motor portion configured to drive the compression portion, and an inverter; the inverter is configured to operate the motor portion in any one of an efficiency mode and a loss mode. The system also includes a controller configured to control an inverter of the compressor based on a minimum temperature of the refrigerant and a freezing temperature of refrigerant oil contained in the refrigerant.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to Korean Patent Application No. 10-2023-0176004 filed in the Korean Intellectual Property Office on December 6, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a heating, ventilation and air conditioning (HVAC) system of a vehicle and a control method thereof. More particularly, the present invention relates to an HVAC system of a vehicle that operates a compressor in a heating mode and a control method thereof. Background Art

[0004] As people pay more and more attention to energy efficiency and environmental issues, there is a need to develop environmentally friendly vehicles that can replace internal combustion engine vehicles. Such environmentally friendly vehicles are divided into electric vehicles that use fuel cells or electricity as a power source for driving, and hybrid electric vehicles that use an engine and a battery for driving.

[0005] Such an environmentally friendly vehicle may include a vehicle thermal management system for thermal management of a vehicle compartment (or passenger compartment), a battery, and the like. The vehicle thermal management system may include a heating, ventilation, and air conditioning (HVAC) system for heating or cooling the air discharged into the vehicle compartment, and a battery cooling system for cooling the battery. The HVAC system may be thermally connected to the battery cooling system via a battery chiller. The battery chiller may include a refrigerant channel through which a refrigerant circulating in the HVAC system flows, and a battery coolant channel through which a battery coolant circulating in the battery cooling system flows. The battery chiller may be designed to cool the battery coolant using a refrigerant.

[0006] The HVAC system may include a refrigerant circulation path through which the refrigerant circulates. The refrigerant circulation path may be fluidly connected to a compressor, an evaporator, an internal condenser, a heating side expansion valve, an external heat exchanger, a cooling side expansion valve, and the like.

[0007] When the HVAC system is operated in a heating mode when the outside temperature of the vehicle is low, the cabin heating performance achieved by the refrigerant circulating in the HVAC system may be relatively reduced. In addition, the consumption of electric energy may increase with the use of electric vehicles.

[0008] In addition, when the HVAC system is operated in a heating mode under low temperature conditions and the minimum temperature of the refrigerant is relatively reduced below the freezing temperature of the refrigerant oil contained in the refrigerant, the refrigerant oil contained in the refrigerant may freeze and the density of the refrigerant may decrease, thereby limiting the RPM of the compressor. Accordingly, when the HVAC system is operated in the heating mode, the amount of heat transferred from the refrigerant to the vehicle cabin may be limited.

[0009] The above information described in this background technology section is provided to help understand the background technology of the present invention. The background technology section may include any technical concepts that are not considered to be prior art (in other words, technologies known to a person of ordinary skill in the art). Summary of the invention

[0010] The present invention is intended to solve the above-mentioned problems arising in the prior art while completely maintaining the advantages achieved by the prior art.

[0011] One aspect of the present invention provides a vehicle thermal management system including a heating, ventilation and air conditioning (HVAC) system of a vehicle and a control method thereof to control an inverter of a compressor based on a temperature of a refrigerant, a freezing temperature of refrigerant oil, and a component temperature of the compressor, thereby preventing freezing of the refrigerant oil and improving cabin heating performance.

[0012] According to one aspect of the present invention, a HVAC system of a vehicle may include a compressor having a compression part, a motor part, and an inverter, wherein the motor part is configured to drive the compression part; and the inverter is configured to operate the motor part in either an efficiency mode or a loss mode. The system may also include a controller configured to control the inverter of the compressor based on a minimum temperature of the refrigerant and a freezing temperature of the refrigerant oil contained in the refrigerant.

[0013] The controller may be configured to control the inverter of the compressor to operate in a heating mode when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is lower than a threshold value and the component temperature of the compressor is lower than an acceptable temperature. The heating mode may refer to a mode in which additional heat is generated from the compressor when the inverter operates the motor part in a loss mode.

[0014] The controller may be configured to calculate the required heat and the maximum heat capacity of the vehicle when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is below a threshold value. The maximum heat capacity may refer to the maximum amount of heat transferred from the refrigerant to the vehicle cabin when the HVAC system is operating in a heating mode.

[0015] In one embodiment, when the maximum heat capacity is lower than the heat required by the vehicle, the controller may be configured to select a control mode and control parameters of the motor portion of the compressor based on the difference between the heat required by the vehicle and the maximum heat capacity. The controller may be configured to calculate the heat generated from the compressor based on the selected control mode and control parameters, and estimate the component temperature of the compressor based on the calculated heat.

[0016] The controller may be configured to operate an inverter controlling the compressor in a heating mode when the estimated component temperature is below an acceptable temperature.

[0017] The controller may be configured to estimate vibration and noise levels generated by the compressor and the refrigerant based on the selected control mode and control parameters when the estimated component temperature is below an acceptable temperature.

[0018] The controller may be configured to control the inverter of the compressor to operate in a heating mode when vibration and noise levels generated by the compressor and the refrigerant are below acceptable vibration and noise levels.

[0019] According to another aspect of the present invention, a method for controlling a heating, ventilation and air conditioning (HVAC) system of a vehicle is provided. The system may include a compressor having: a compression part, a motor part and an inverter, wherein the motor part is configured to drive the compression part; and the inverter is configured to operate the motor part in either an efficiency mode or a loss mode. The method may include: operating the HVAC system in a heating mode; and controlling, by a controller, an inverter of the compressor based on a minimum temperature of a refrigerant and a freezing temperature of a refrigerant oil contained in the refrigerant.

[0020] The control of the inverter may include: when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is lower than a threshold value and the component temperature of the compressor is lower than an acceptable temperature, the controller controls the inverter of the compressor to operate in a heating mode. The heating mode may refer to a mode in which additional heat is generated from the compressor when the inverter operates the motor part in a loss mode.

[0021] The control of the inverter may include: when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is lower than a threshold value, the controller calculates the required heat of the vehicle and the maximum heat capacity. The maximum heat capacity may refer to the maximum amount of heat transferred from the refrigerant to the vehicle cabin when the HVAC system is operating in the heating mode.

[0022] When the maximum heat capacity is lower than the heat required by the vehicle, the control of the inverter may include: selecting, by the controller, a control mode and a control parameter of the motor portion of the compressor based on the difference between the heat required by the vehicle and the maximum heat capacity. The control of the inverter may also include: calculating, by the controller, the heat generated from the compressor based on the selected control mode and control parameter; and estimating, by the controller, the component temperature of the compressor based on the calculated heat.

[0023] The controlling of the inverter may include controlling, by the controller, the inverter of the compressor to operate in a heating mode when the estimated component temperature is below an acceptable temperature.

[0024] The controlling of the inverter may include estimating, by the controller, vibration and noise levels generated by the compressor and the refrigerant based on the selected control mode and control parameters when the estimated component temperature is below an acceptable temperature.

[0025] The controlling of the inverter may include controlling, by the controller, the inverter of the compressor to operate in a heating mode when vibration and noise levels generated by the compressor and the refrigerant are lower than acceptable vibration and noise levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings:

[0027] Figure 1 A heating, ventilation and air conditioning (HVAC) system for a vehicle according to an embodiment of the present invention is shown; and

[0028] Figure 2 A flow chart showing a method of controlling an HVAC system of a vehicle according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention are described in detail with reference to the accompanying drawings. In the entire accompanying drawings, the same reference numerals are used to represent the same or equivalent elements. In addition, in order not to unnecessarily obscure the subject matter of the present invention, the detailed description of the known techniques related to the present invention is omitted.

[0030] Terms such as first, second, A, B, (a) and (b) can be used to describe the elements in embodiments of the present invention. These terms are only used to distinguish an element from another element, and the inherent characteristics, sequence or order of the corresponding elements, etc. are not limited by these terms. Unless otherwise defined, all terms used herein (including technical terms or scientific terms) have the same meaning as those terms commonly understood by those of ordinary skill in the field to which the present invention belongs. These terms defined in commonly used dictionaries should be interpreted as having the meaning consistent with the contextual meaning in the relevant technical field, and unless clearly defined in the application as having an idealized or overly formal meaning, these terms should not be interpreted as having an idealized or overly formal meaning.

[0031] When the controller, component, device, element, part, unit, module, etc. of the present invention is described as having a purpose or performing an operation, function, etc., the controller, component, device, element, part, unit or module should be considered as "configured to" meet the purpose or perform the operation or function. Each controller, component, device, element, part, unit, module, etc. can be implemented separately or include a processor and memory as part of the device, such as a non-transitory computer-readable medium.

[0032] refer to Figure 1 , the heating, ventilation and air conditioning (HVAC) system 11 of the vehicle according to the embodiment of the present invention can be configured to heat or cool the air in the cabin of the vehicle using the refrigerant circulating in the refrigerant circulation path 21. The refrigerant circulation path 21 can be fluidly connected to the evaporator 31, the compressor 32, the interior condenser 33, the heating side expansion valve 16, the water-cooled heat exchanger 70, the exterior heat exchanger 35 and the cooling side expansion valve 15. Figure 1 In the refrigerant circulation path 21 , the refrigerant may sequentially flow through the compressor 32 , the internal condenser 33 , the heating-side expansion valve 16 , the water-cooled heat exchanger 70 , the external heat exchanger 35 , the cooling-side expansion valve 15 , and the evaporator 31 .

[0033] The evaporator 31 may be configured to evaporate the refrigerant received from the cooling-side expansion valve 15. In other words, the refrigerant expanded by the cooling-side expansion valve 15 may absorb heat from the air and evaporate in the evaporator 31. During the cooling operation of the HVAC system 11, the evaporator 31 may be configured to cool the air using the refrigerant cooled by the external heat exchanger 35 and expanded by the cooling-side expansion valve 15, and the air cooled by the refrigerant may be guided to the passenger compartment.

[0034] The compressor 32 may be configured to compress the refrigerant received from the evaporator 31 and / or the battery chiller 37. According to an embodiment, the compressor 32 may be an inverter compressor including an inverter 32c.

[0035] The compressor 32 may compress the refrigerant to circulate the refrigerant through the refrigerant circulation path 21 .

[0036] According to an embodiment of the present invention, the compressor 32 may include: a compression part 32a that compresses the refrigerant, a motor part 32b that drives the compression part 32a, and an inverter 32c that controls the motor part 32b. The compressor 32 may have a refrigerant passage 32d disposed in the inverter 32c and the motor part 32b, and the refrigerant may flow into the compression part 32a through the refrigerant passage 32d.

[0037] The interior condenser 33 may be configured to condense the refrigerant received from the compressor 32. Accordingly, the refrigerant flowing through the inner passage of the interior condenser 33 may heat the air passing through the interior condenser 33. When the air heated by the interior condenser 33 is guided to the vehicle cabin, heating of the vehicle cabin may be performed.

[0038] The external heat exchanger 35 may be arranged adjacent to the front grille of the vehicle, and the external heat exchanger 35 may be exposed to the outside so that heat may be transferred between the external heat exchanger 35 and the ambient air. During the cooling operation of the HVAC system 11, the external heat exchanger 35 may be configured to condense the refrigerant received from the internal condenser 33. In other words, the external heat exchanger 35 may be used as an external condenser that condenses the refrigerant by transferring heat to the ambient air during the cooling operation of the HVAC system 11. During the heating operation of the HVAC system 11, the external heat exchanger 35 may be configured to evaporate the refrigerant received from the water-cooled heat exchanger 70. In other words, the external heat exchanger 35 may be used as an external evaporator that evaporates the refrigerant by absorbing heat from the ambient air. In particular, the external heat exchanger 35 may perform heat exchange with the ambient air forcibly blown by the cooling fan 75, so that the heat transfer rate between the external heat exchanger 35 and the ambient air may be further improved.

[0039] The water-cooled heat exchanger 70 may be configured to transfer heat between the refrigerant circulation path 21 of the HVAC system 11, the battery coolant circulation path 22 of the battery cooling system 12, and the PE coolant circulation path 23 of the power electronics (PE) cooling system 13. Specifically, the water-cooled heat exchanger 70 may be arranged between the internal condenser 33 and the external heat exchanger 35 on the refrigerant circulation path 21. The water-cooled heat exchanger 70 may include: a refrigerant channel 71 fluidly connected to the refrigerant circulation path 21, a first coolant channel 72 fluidly connected to the PE coolant circulation path 23, and a second coolant channel 73 fluidly connected to the battery coolant circulation path 22.

[0040] During the heating operation of the HVAC system 11, the water-cooled heat exchanger 70 can be configured to evaporate the refrigerant received from the interior condenser 33 using the heat transferred from the PE cooling system 13. In other words, during the heating operation of the HVAC system 11, the water-cooled heat exchanger 70 can be used as an evaporator that evaporates the refrigerant by recovering waste heat from the motor 51 and the PE component 52 of the PE cooling system 13.

[0041] During the cooling operation of the HVAC system 11, the water-cooled heat exchanger 70 may be configured to condense the refrigerant received from the interior condenser 33. The water-cooled heat exchanger 70 may function as a condenser that cools the refrigerant by using the battery coolant circulating in the battery coolant circulation path 22 of the battery cooling system 12 and the PE coolant circulating in the PE coolant circulation path 23 of the PE cooling system 13 to condense the refrigerant.

[0042] The heating-side expansion valve 16 may be disposed on the upstream side of the water-cooled heat exchanger 70 in the refrigerant circulation path 21. Specifically, the heating-side expansion valve 16 may be disposed between the interior condenser 33 and the water-cooled heat exchanger 70. The heating-side expansion valve 16 may adjust the flow of the refrigerant flowing into the water-cooled heat exchanger 70 and / or the flow rate of the refrigerant during the heating operation of the HVAC system 11. The heating-side expansion valve 16 may be configured to expand the refrigerant received from the interior condenser 33 during the heating operation of the HVAC system 11.

[0043] According to the embodiment, the heating side expansion valve 16 may be an electronic expansion valve (EXV) having a drive motor 16a. The drive motor 16a may have a shaft that can be moved to open or close an orifice defined in a valve body of the heating side expansion valve 16, and the position of the shaft may vary according to the rotation direction, degree of rotation, etc. of the drive motor 16a. Accordingly, the opening of the orifice of the heating side expansion valve 16 may vary. The controller 100 may control the operation of the drive motor 16a. The heating side expansion valve 16 may be a fully open type EXV.

[0044] The opening degree of the heating side expansion valve 16 may be changed under the control of the controller 100. As the opening degree of the heating side expansion valve 16 changes, the flow rate of the refrigerant flowing into the refrigerant passage 71 of the water-cooled heat exchanger 70 may change. The heating side expansion valve 16 may be controlled by the controller 100 during the heating operation of the HVAC system 11.

[0045] The cooling side expansion valve 15 may be arranged between the external heat exchanger 35 and the evaporator 31 in the refrigerant circulation path 21. The cooling side expansion valve 15 may be arranged on the upstream side of the evaporator 31 so that it can adjust the flow of the refrigerant flowing into the evaporator 31 and / or the flow rate of the refrigerant. In addition, the cooling side expansion valve 15 may be configured to expand the refrigerant received from the external heat exchanger 35.

[0046] According to an embodiment, the cooling side expansion valve 15 may be a thermal expansion valve (TXV) that senses the temperature and / or pressure of the refrigerant and adjusts the opening of the cooling side expansion valve 15. Specifically, the cooling side expansion valve 15 may be a TXV having a shutoff valve 15a that selectively blocks or does not block the refrigerant from flowing into the internal passage of the cooling side expansion valve 15. The shutoff valve 15a may be a solenoid valve. The shutoff valve 15a may be opened or closed by the controller 100 so that the shutoff valve 15a may not block or block the refrigerant from flowing into the cooling side expansion valve 15. When the shutoff valve 15a is opened, the refrigerant may flow into the cooling side expansion valve 15, and when the shutoff valve 15a is closed, the refrigerant may be blocked from flowing into the cooling side expansion valve 15. According to an embodiment, the shutoff valve 15a may be installed in the valve body of the cooling side expansion valve 15, thereby opening or closing the internal passage of the cooling side expansion valve 15. According to another embodiment, the shutoff valve 15a may be arranged on the upstream side of the cooling side expansion valve 15, thereby selectively opening or closing the inlet of the cooling side expansion valve 15.

[0047] When the stop valve 15a is closed, the cooling-side expansion valve 15 may be blocked, and accordingly, the refrigerant may not be guided to the cooling-side expansion valve 15 and the evaporator 31, but may be guided only to the battery chiller 37. In other words, when the stop valve 15a of the cooling-side expansion valve 15 is closed, the cooling operation of the HVAC system 11 may not be performed, and only the battery chiller 37 may be cooled or the heating operation of the HVAC system 11 may be performed. When the stop valve 15a is opened, the refrigerant may be guided to the cooling-side expansion valve 15 and the evaporator 31. In other words, when the stop valve 15a of the cooling-side expansion valve 15 is opened, the cooling operation of the HVAC system 11 may be performed.

[0048] The HVAC system 11 may include an HVAC housing 30 having an inlet and an outlet. The HVAC housing 30 may be configured to allow air to flow into the cabin of the vehicle. An evaporator 31 and an interior condenser 33 may be located in the HVAC housing 30. An air mixing door 34a may be disposed between the evaporator 31 and the interior condenser 33, and a positive temperature coefficient (PTC) heater 34b may be disposed on a downstream side of the interior condenser 33.

[0049] The HVAC system 11 may further include an accumulator 38 disposed between the evaporator 31 and the compressor 32 in the refrigerant circulation path 21, and the accumulator 38 may be located on the downstream side of the evaporator 31. The accumulator 38 may separate liquid refrigerant from the refrigerant received by the evaporator 31, thereby preventing the liquid refrigerant from flowing into the compressor 32.

[0050] The HVAC system 11 may further include a branch line 36 branching from the refrigerant circulation path 21. The branch line 36 may branch from an upstream point of the cooling-side expansion valve 15 in the refrigerant circulation path 21 and be connected to the compressor 32. A battery chiller 37 may be fluidly connected to the branch line 36, and the battery chiller 37 may be configured to transfer heat between the branch line 36 and the battery coolant circulation path 22. In other words, the battery chiller 37 may be configured to transfer heat between the refrigerant circulating in the HVAC system 11 and the battery coolant circulating in the battery cooling system 12.

[0051] Specifically, the battery chiller 37 may include a first channel 37a fluidly connected to the branch line 36 and a second channel 37b fluidly connected to the battery coolant circulation path 22. The first channel 37a and the second channel 37b may be adjacent to or in contact with each other in the battery chiller 37. The first channel 37a may be fluidly separated from the second channel 37b. Accordingly, the battery chiller 37 may be configured to transfer heat between the battery coolant flowing through the second channel 37b and the refrigerant flowing through the first channel 37a. The refrigerant may absorb heat from the battery coolant so that the refrigerant may evaporate and overheat, and the battery coolant may release heat to the refrigerant so that the battery coolant may cool.

[0052] The branch line 36 may be fluidly connected to the accumulator 38 , and the refrigerant flowing through the branch line 36 may be contained in the accumulator 38 .

[0053] The chiller-side expansion valve 17 may be disposed in the branch line 36 on the upstream side of the battery chiller 37. The chiller-side expansion valve 17 may adjust the flow of the refrigerant and / or the flow rate of the refrigerant flowing into the battery chiller 37. The chiller-side expansion valve 17 may be configured to expand the refrigerant received from the external heat exchanger 35.

[0054] According to the embodiment, the chiller side expansion valve 17 may be an EXV having a drive motor 17a. The drive motor 17a may have a shaft that can be moved to open or close an orifice defined in the valve body of the chiller side expansion valve 17. The position of the shaft may vary according to the rotation direction, degree of rotation, etc. of the drive motor 17a. Accordingly, the opening degree of the chiller side expansion valve 17 may vary. In other words, as the controller 100 controls the operation of the drive motor 17a, the opening degree of the chiller side expansion valve 17 may vary. The chiller side expansion valve 17 may be a fully open type EXV. The chiller side expansion valve 17 may have a structure that is the same as or similar to that of the heating side expansion valve 16.

[0055] As the opening of the chiller-side expansion valve 17 changes, the flow rate of the refrigerant flowing into the battery chiller 37 may change. For example, when the opening of the chiller-side expansion valve 17 is greater than a reference opening, the flow rate of the refrigerant flowing into the battery chiller 37 may be relatively increased to be above the reference flow rate. In addition, when the opening of the chiller-side expansion valve 17 is less than the reference opening, the flow rate of the refrigerant flowing into the battery chiller 37 may be similar to the reference flow rate or relatively reduced to be below the reference flow rate. The reference opening refers to the opening of the chiller-side expansion valve 17 required to maintain the target temperature of the evaporator, and the reference flow rate refers to the flow rate of the refrigerant flowing into the battery chiller 37 when the chiller-side expansion valve 17 is opened to the reference opening. Accordingly, when the chiller-side expansion valve 17 is opened to the reference opening, the refrigerant may flow into the battery chiller 37 at the corresponding reference flow rate.

[0056] When the opening of the chiller-side expansion valve 17 is adjusted by the controller 100, the flow rate of the refrigerant flowing into the battery chiller 37 may be changed, and accordingly, the flow rate of the refrigerant flowing into the evaporator 31 may be changed. When the opening of the chiller-side expansion valve 17 is adjusted, the refrigerant may be distributed to the evaporator 31 and the battery chiller 37 at a predetermined ratio. Accordingly, the cooling of the HVAC system 11 and the cooling of the battery chiller 37 may be performed simultaneously or selectively.

[0057] The HVAC system 11 may further include a refrigerant bypass line 39 that connects a downstream point of the refrigerant passage 71 of the water-cooled heat exchanger 70 and the branch line 36. The inlet of the refrigerant bypass line 39 may be connected to a downstream point of the water-cooled heat exchanger 70, and the outlet of the refrigerant bypass line 39 may be connected to the branch line 36. Specifically, the inlet of the refrigerant bypass line 39 may be connected to a point between the water-cooled heat exchanger 70 and the external heat exchanger 35, and the outlet of the refrigerant bypass line 39 may be connected to a point between the battery chiller 37 and the compressor 32 in the branch line 36. The first three-way valve 61 may be arranged at a connection point between the inlet of the refrigerant bypass line 39 and the refrigerant circulation path 21. Accordingly, the first three-way valve 61 may be arranged between the water-cooled heat exchanger 70 and the external heat exchanger 35 in the refrigerant circulation path 21. When the first three-way valve 61 is switched to open the inlet of the refrigerant bypass line 39, the refrigerant flowing through the refrigerant passage 71 of the water-cooled heat exchanger 70 may be guided to the compressor 32 through the refrigerant bypass line 39 and the accumulator 38. In other words, when the inlet of the refrigerant bypass line 39 is opened by the switching of the first three-way valve 61, the refrigerant may bypass the external heat exchanger 35. When the first three-way valve 61 is switched to close the inlet of the refrigerant bypass line 39, the refrigerant flowing through the refrigerant passage 71 of the water-cooled heat exchanger 70 may not flow through the refrigerant bypass line 39, but may be guided to the external heat exchanger 35. In other words, when the inlet of the refrigerant bypass line 39 is closed by the switching of the first three-way valve 61, the refrigerant may flow through the external heat exchanger 35.

[0058] The controller 100 may be configured to control respective operations of the stop valve 15a of the cooling-side expansion valve 15, the heating-side expansion valve 16, the chiller-side expansion valve 17, the compressor 32, etc. Thus, the overall operation of the HVAC system 11 may be controlled by the controller 100. According to an embodiment, the controller 100 may be a fully automatic temperature control (FATC) system.

[0059] When the HVAC system 11 operates in cooling mode, the shut-off valve 15a of the cooling side expansion valve 15 can be opened, and the refrigerant can flow through the compressor 32, the internal condenser 33, the heating side expansion valve 16, the refrigerant channel 71 of the water-cooled heat exchanger 70, the external heat exchanger 35, the cooling side expansion valve 15 and the evaporator 31 in sequence.

[0060] The battery cooling system 12 may be configured to cool the battery 41 using the battery coolant circulating in the battery coolant circulation path 22. The battery coolant circulation path 22 may be fluidly connected to the battery 41, the heater 42, the battery chiller 37, the second battery pump 45, the battery radiator 43, the reservoir 48, and the first battery pump 44. Figure 1In the battery coolant circulation path 22, the battery 41, the heater 42, the battery chiller 37, the second battery pump 45, the battery radiator 43, the liquid storage tank 48, the second coolant channel 73 of the water-cooled heat exchanger 70 and the first battery pump 44 can be flowed through in sequence.

[0061] The battery 41 may have a cooling liquid channel provided inside or outside, through which the battery cooling liquid may flow. The battery cooling liquid circulation path 22 may be fluidly connected to the cooling liquid channel of the battery 41 .

[0062] The heater 42 may be disposed between the battery chiller 37 and the battery 41, and the heater 42 may be configured to heat the battery coolant circulating in the battery coolant circulation path 22, thereby heating the coolant. According to an embodiment, the heater 42 may be a water-heating heater that heats the coolant by exchanging heat with a high-temperature fluid. According to another embodiment, the heater 42 may be an electric heater.

[0063] The battery radiator 43 may be adjacent to the front grille of the vehicle, and the battery radiator 43 may be cooled using ambient air forced by the cooling fan 75. The battery radiator 43 may be adjacent to the external heat exchanger 35.

[0064] The first battery pump 44 may be configured to circulate the battery coolant through at least a portion of the battery coolant circulation path 22. The second battery pump 45 may be configured to circulate the battery coolant through at least a portion of the battery coolant circulation path 22.

[0065] The first battery pump 44 may be located at a point upstream of the battery 41 in the battery coolant circulation path 22 . Accordingly, the first battery pump 44 may be configured to forcibly pump the battery coolant into the battery 41 , thereby causing the battery coolant to flow through the battery 41 .

[0066] The second battery pump 45 may be located at an upstream point of the battery radiator 43 in the battery coolant circulation path 22. Accordingly, the second battery pump 45 may be configured to forcefully pump the battery coolant into the inlet of the battery radiator 43, thereby causing the battery coolant to flow through the battery radiator 43.

[0067] The first battery pump 44 and the second battery pump 45 may be individually and selectively operated according to the thermal condition and charging condition of the battery 41 , the operating condition of the HVAC system 11 , and the like.

[0068] The fluid reservoir 48 may be disposed between the outlet of the battery radiator 43 and the inlet of the first battery pump 44 .

[0069] The battery cooling system 12 may further include a first battery bypass line 46 that allows the battery coolant to bypass the battery radiator 43. The first battery bypass line 46 may be configured to directly connect a point upstream of the battery radiator 43 and a point downstream of the battery radiator 43 in the battery coolant circulation path 22.

[0070] The inlet of the first battery bypass line 46 may be connected to a point between the battery chiller 37 and the inlet of the battery radiator 43 in the battery coolant circulation path 22. Specifically, the inlet of the first battery bypass line 46 may be connected to a point between the battery chiller 37 and the inlet of the second battery pump 45 in the battery coolant circulation path 22.

[0071] The outlet of the first battery bypass line 46 may be connected to a point between the first battery pump 44 and the outlet of the battery radiator 43 in the battery coolant circulation path 22. Specifically, the outlet of the first battery bypass line 46 may be connected to a point between the outlet of the reservoir tank 48 and the first battery pump 44 in the battery coolant circulation path 22.

[0072] The battery coolant can be guided from the downstream side of the battery chiller 37 to the upstream side of the first battery pump 44 through the first battery bypass line 46, so that the battery coolant can bypass the second battery pump 45, the battery radiator 43, the liquid storage tank 48 and the water-cooled heat exchanger 70. Accordingly, the battery coolant flowing through the first battery bypass line 46 can flow through the battery 41, the heater 42 and the battery chiller 37 in sequence through the first battery pump 44.

[0073] The battery cooling system 12 may further include a second battery bypass line 47 that allows the battery coolant to bypass the battery 41, the heater 42, and the battery chiller 37. The second battery bypass line 47 may be configured to directly connect a point downstream of the battery chiller 37 and a point upstream of the battery 41 in the battery coolant circulation path 22.

[0074] The inlet of the second battery bypass line 47 may be connected to a point between the outlet of the first battery bypass line 46 and the outlet of the battery radiator 43 in the battery coolant circulation path 22. Specifically, the inlet of the second battery bypass line 47 may be connected to a point between the outlet of the reservoir tank 48 and the outlet of the first battery bypass line 46 in the battery coolant circulation path 22.

[0075] The outlet of the second battery bypass line 47 may be connected to a point between the inlet of the first battery bypass line 46 and the inlet of the battery radiator 43 in the battery coolant circulation path 22. Specifically, the outlet of the second battery bypass line 47 may be connected to a point between the inlet of the first battery bypass line 46 and the inlet of the second battery pump 45 in the battery coolant circulation path 22. The battery coolant may be guided from the downstream side of the battery radiator 43 to the upstream side of the second battery pump 45 through the second battery bypass line 47, so that the battery coolant may bypass the battery 41, the heater 42, and the battery chiller 37. Accordingly, the battery coolant flowing through the second battery bypass line 47 may flow through the battery radiator 43, the reservoir 48, and the second coolant channel 73 of the water-cooled heat exchanger 70 in sequence through the second battery pump 45.

[0076] The first battery bypass line 46 and the second battery bypass line 47 may be connected in parallel with each other.

[0077] The battery cooling system 12 may further include a second three-way valve 62 disposed at the inlet of the first battery bypass line 46. In other words, the second three-way valve 62 may be disposed at the connection between the inlet of the first battery bypass line 46 and the battery coolant circulation path 22. When the second three-way valve 62 is switched to open the inlet of the first battery bypass line 46, a portion of the battery coolant (battery coolant discharged from the battery chiller 37) may flow through the first battery bypass line 46, so that a portion of the battery coolant may bypass the battery radiator 43, and the rest of the battery coolant (battery coolant discharged from the battery radiator 43) may flow through the second battery bypass line 47, so that the rest of the battery coolant may bypass the battery 41, the heater 42, and the battery chiller 37. In other words, when the inlet of the first battery bypass line 46 is opened by switching the second three-way valve 62, the battery coolant circulation path 22 can form a coolant circulation loop independent of each other through the first battery bypass line 46 and the second battery bypass line 47. The battery coolant flowing through the first battery bypass line 46 can bypass the second battery pump 45, the battery radiator 43, the liquid storage tank 48 and the water-cooled heat exchanger 70. The battery coolant can flow through the battery 41, the heater 42 and the battery chiller 37 in sequence through the operation of the first battery pump 44. The battery coolant flowing through the second battery bypass line 47 can bypass the first battery pump 44, the battery 41, the heater 42 and the battery chiller 37. The coolant can flow through the battery radiator 43, the liquid storage tank 48 and the water-cooled heat exchanger 70 in sequence through the operation of the second battery pump 45.

[0078] When the second three-way valve 62 is switched to close the inlet of the first battery bypass line 46, the battery coolant may not flow through the first battery bypass line 46. In other words, when the inlet of the first battery bypass line 46 is closed by switching the second three-way valve 62, the battery coolant may circulate through the battery coolant circulation path 22.

[0079] The battery cooling system 12 may be controlled by a battery management system 110. The battery management system 110 may monitor the state of the battery 41, and perform cooling of the battery 41 when the temperature of the battery 41 rises to a threshold temperature or higher. The battery management system 110 may send an instruction for cooling the battery 41 to the controller 100. Accordingly, the controller 100 may operate the compressor 32 and open the chiller-side expansion valve 17. When the operation of the HVAC system 11 is not required during the cooling operation of the battery 41, the controller 100 may close the cooling-side expansion valve 15. In addition, the battery management system 110 may control the operation of the first battery pump 44 and the switching operation of the second three-way valve 62, so that the battery coolant may bypass the battery radiator 43 and flow through the battery 41 and the battery chiller 37 as needed.

[0080] The PE cooling system 13 may be configured to cool the motor 51 and the PE component 52 of the electric PE system using the PE coolant circulating in the PE coolant circulation path 23. The PE coolant circulation path 23 may be fluidly connected to the motor 51, the PE component 52, the PE radiator 53, the PE pump 54, and the liquid storage tank 56. Figure 1 In the embodiment, the PE coolant may flow sequentially through the motor 51, the PE radiator 53, the liquid storage tank 56, the first coolant channel 72 of the water-cooled heat exchanger 70 and the PE component 52 in the PE coolant circulation path 23.

[0081] The motor 51 may have a coolant channel provided inside or outside, through which the PE coolant may flow. The PE coolant circulation path 23 may be fluidly connected to the coolant channel of the motor 51.

[0082] The PE component 52 may include at least one PE component related to the driving of the motor 51, such as an inverter, an OBC, and an LDC. The PE component 52 may have a coolant channel disposed inside or outside, through which the PE coolant may flow. The PE coolant circulation path 23 may be fluidically connected to the coolant channel of the PE component 52.

[0083] The PE radiator 53 may be adjacent to the front grille of the vehicle, and the PE radiator 53 may be cooled using ambient air forcibly blown by the cooling fan 75. The external heat exchanger 35, the battery radiator 43, and the PE radiator 53 may be arranged adjacent to each other at the front of the vehicle, and the cooling fan 75 may be arranged behind the external heat exchanger 35, the battery radiator 43, and the PE radiator 53.

[0084] The PE pump 54 may be disposed on an upstream side of the motor 51 and the PE assembly 52 , and the PE pump 54 may be configured to circulate the coolant in the PE coolant circulation path 23 .

[0085] The PE cooling system 13 may further include a PE bypass line 55 that allows the PE coolant to bypass the PE radiator 53. The PE bypass line 55 may be configured to directly connect an upstream point of the PE radiator 53 and a downstream point of the PE radiator 53 in the PE coolant circulation path 23, so that the PE coolant discharged from the outlet of the motor 51 may be guided to the inlet of the PE pump 54 through the PE bypass line 55. Accordingly, the PE coolant may bypass the PE radiator 53.

[0086] The inlet of the PE bypass line 55 may be connected to a point between the motor 51 and the PE radiator 53 in the PE coolant circulation path 23. The outlet of the PE bypass line 55 may be connected to a point between the reservoir tank 56 and the PE assembly 52 in the PE coolant circulation path 23. Specifically, the outlet of the PE bypass line 55 may be connected to a point between the reservoir tank 56 and the inlet of the PE pump 54 in the PE coolant circulation path 23.

[0087] The PE cooling system 13 may further include a third three-way valve 63 disposed at the inlet of the PE bypass line 55. The PE coolant may bypass the PE radiator 53 via the PE bypass line 55 by switching the third three-way valve 63. The PE coolant may flow through the motor 51, the first coolant channel 72 of the water-cooled heat exchanger 70, and the PE assembly 52 in sequence through the PE pump 54.

[0088] The reservoir tank 56 may be disposed on the downstream side of the PE radiator 53. In particular, the reservoir tank 56 may be disposed between the PE radiator 53 and the first coolant channel 72 of the water-cooled heat exchanger 70 in the PE coolant circulation path 23.

[0089] The switching of the third three-way valve 63 and the operation of the PE pump 54 in the PE cooling system 13 may be controlled by the controller 100 .

[0090] When the HVAC system 11 operates in the heating mode, the stop valve 15a of the cooling side expansion valve 15 may be closed, the opening degree of the heating side expansion valve 16 may be adjusted, and the first three-way valve 61 may be switched to open the inlet of the refrigerant bypass line 39. The refrigerant compressed by the compressor 32 may be condensed in the interior condenser 33, and the refrigerant condensed by the interior condenser 33 may be expanded in the heating side expansion valve 16. The expanded refrigerant may evaporate in the refrigerant passage 71 of the water-cooled heat exchanger 70, and the evaporated refrigerant may be guided to the compressor 32 through the refrigerant bypass line 39. Thus, the refrigerant may flow through the compressor 32, the interior condenser 33, the heating side expansion valve 16, and the water-cooled heat exchanger 70 in sequence.

[0091] According to an embodiment of the present invention, the controller 100 may control the inverter 32c of the compressor 32 in such a manner that the motor portion 32b of the compressor 32 operates in either an efficiency mode or a loss mode. The inverter 32c may be configured to operate the motor portion 32b in either an efficiency mode or a loss mode. The heat generated from the compressor 32 when the motor portion 32b operates in the loss mode may be higher than the heat generated from the compressor 32 when the motor portion 32b operates in the efficiency mode. In other words, when the motor portion 32b operates in the loss mode under the control of the inverter 32c, additional heat may be generated from the compressor 32.

[0092] According to an embodiment of the present invention, the controller 100 may be configured to control the inverter 32c of the compressor 32 based on the minimum temperature "Tr" of the refrigerant and the freezing temperature "To" of the refrigerant oil contained in the refrigerant when the HVAC system 11 operates in a heating mode.

[0093] According to an embodiment of the present invention, in a state where the HVAC system 11 is operated in a heating mode, when the temperature difference (Tr-To) between the lowest temperature Tr of the refrigerant and the freezing temperature To of the refrigerant oil contained in the refrigerant is lower than the threshold a and the component temperature Te of the compressor 32 is lower than the acceptable temperature, the controller 100 may be configured to control the inverter 32c of the compressor 32 in such a manner that the compressor 32 is operated in a heating mode. The heating mode refers to a mode in which additional heat is generated from the compressor 32 when the inverter 32c causes the motor part 32b to operate in a loss mode under the control of the controller 100. In other words, when the motor part 32b is operated in a loss mode, additional heat may be generated from the components of the compressor 32 (e.g., the power device of the inverter 32c and the coil of the motor part 32b). Accordingly, the temperature of the refrigerant discharged from the compressor 32 may be relatively increased, so that the refrigerant oil contained in the refrigerant may be prevented from freezing. In particular, the additional heat generated from the compressor 32 may be transferred to the vehicle cabin through the refrigerant, thereby improving the vehicle cabin heating performance.

[0094] According to an embodiment of the present invention, when it is determined that the temperature difference between the lowest temperature "Tr" of the refrigerant and the freezing temperature "To" of the refrigerant oil contained in the refrigerant (i.e., Tr-To) is lower than the threshold value "a", the controller 100 can be configured to calculate the required heat "Hr" and the maximum heat capacity "Hm" of the vehicle. The required heat Hr of the vehicle refers to the sum of the heat required to heat the vehicle cabin based on the heating temperature set by the occupant and the required heat of the battery 41 received from the battery management system 110. The maximum heat capacity Hm refers to the maximum amount of heat transferred from the refrigerant circulating in the refrigerant circulation path 21 of the HVAC system 11 to the vehicle cabin when the HVAC system 11 is operating in the heating mode.

[0095] According to an embodiment of the present invention, when the maximum heat capacity Hm is lower than the required heat capacity Hr of the vehicle, the controller 100 may be configured to select the most appropriate control mode and control parameters among the control modes and control parameters of the motor portion 32b of the compressor 32 based on the difference between the required heat capacity Hr of the vehicle and the maximum heat capacity Hm (i.e., Hr-Hm). The controller 100 may also calculate the heat generated from the compressor 32 based on the selected control mode and control parameters, and estimate the component temperature "Te" of the compressor 32 based on the calculated heat.

[0096] According to an embodiment of the present invention, when the estimated component temperature Te is lower than the first acceptable temperature "T1", the controller 100 may control the inverter 32c of the compressor 32 in such a manner that the compressor 32 operates in the heating mode. Accordingly, when the motor portion 32b operates in the loss mode under the control of the inverter 32c based on the selected control mode and control parameters, additional heat may be generated from the components of the compressor 32.

[0097] Figure 2 A flow chart showing a method of controlling an HVAC system of a vehicle according to an embodiment of the present invention is shown.

[0098] The HVAC system 11 may operate in a heating mode (step S1 ), and the controller 100 may monitor the temperature of the refrigerant sensed by the refrigerant temperature sensor and check the freezing temperature of the refrigerant oil contained in the refrigerant.

[0099] The controller 100 may determine whether the temperature difference between the lowest temperature "Tr" of the refrigerant and the freezing temperature "To" of the refrigerant oil contained in the refrigerant (i.e., Tr-To) is lower than a threshold value "a" (step S2). The threshold value refers to a reference temperature for checking whether the refrigerant oil is frozen at the lowest temperature of the refrigerant.

[0100] When it is determined in step S2 that the temperature difference (Tr-To) between the lowest temperature "Tr" of the refrigerant and the freezing temperature "To" of the refrigerant oil contained in the refrigerant is lower than the threshold value "a", the controller 100 can calculate the required heat "Hr" and the maximum heat capacity "Hm" of the vehicle (step S3). The required heat Hr of the vehicle refers to the sum of the heat required to heat the vehicle cabin based on the heating temperature set by the occupant and the heat required for heating the battery 41 received from the battery management system 110. The maximum heat capacity Hm refers to the maximum amount of heat transferred to the vehicle cabin when the HVAC system 11 operates in the heating mode.

[0101] The controller 100 may determine whether the maximum heat capacity Hm is lower than the vehicle required heat capacity Hr (step S4).

[0102] When it is determined in step S4 that the maximum heat capacity Hm is lower than the required heat capacity Hr of the vehicle, the controller 100 may request the compressor 32 to operate in the heating mode (step S5). The heating mode of the compressor 32 refers to an operating mode in which additional heat is generated from components of the compressor 32 when the motor portion 32b of the compressor 32 is controlled by the inverter 32c to operate in the loss mode.

[0103] The controller 100 may select the most appropriate control mode and control parameter among the control modes and control parameters of the motor portion 32b of the compressor 32 based on the difference between the vehicle required heat amount Hr and the maximum heat capacity Hm (ie, Hr-Hm) (step S6).

[0104] In step S7, the controller 100 may calculate the amount of heat generated from the compressor 32 based on the control mode and control parameters selected in step S6. Specifically, the controller 100 may calculate the amount of heat generated from the compressor 32 by applying the selected control mode and control parameters to the power efficiency map. For example, the amount of heat generated from the compressor 32 may be the sum of the amount of heat generated from the coil of the motor portion 32b and the amount of heat generated from the power device of the inverter 32c.

[0105] The controller 100 may estimate the component temperature "Te" of the compressor 32 based on information about heat transfer between each component of the compressor 32 and the refrigerant (temperature of the refrigerant, flow rate of the refrigerant, revolutions per minute (RPM) of the compressor, etc.) and the calculated heat amount (step S8). For example, the controller 100 may estimate the temperature of the coil of the motor portion 32b and sense the temperature of the power device of the inverter 32c using a temperature sensor.

[0106] The controller 100 may determine whether the estimated component temperature "Te" is lower than the first acceptable temperature "T1" (step S9). The first acceptable temperature T1 refers to a first reference temperature for determining whether each component of the compressor 32 may be damaged due to the generated heat.

[0107] When it is determined in step S9 that the estimated component temperature Te is lower than the first acceptable temperature T1, the controller 100 may estimate the vibration and noise level V1 generated by the compressor 32 and the flow of the refrigerant based on the selected control mode and control parameters (step S10). When the compressor 32 is controlled to operate in the loss mode, the compressor 32 may physically vibrate. Since the vibration is transmitted from the compressor 32 to the refrigerant flowing through the refrigerant circulation path 21, vibration and noise may be generated by the compressor 32 and the flow of the refrigerant.

[0108] The controller 100 may calculate an acceptable vibration and noise level V2 based on various operating conditions (vehicle speed, blower noise, vehicle audio, etc.) (step S11 ).

[0109] The controller 100 may determine whether a vibration and noise level V1 generated by the compressor 32 and the flow of the refrigerant is lower than an acceptable vibration and noise level V2 (step S12 ).

[0110] When it is determined that the vibration and noise level V1 generated by the compressor 32 and the flow of the refrigerant is lower than the acceptable vibration and noise level V2, the controller 100 may operate the compressor 32 in the heating mode based on the selected control mode and control parameters (step S13). In order to operate the motor part 32b in the loss mode under the control of the inverter 32c based on the selected control mode and control parameters, the controller 100 may control the inverter 32c of the compressor 32 in such a manner that the compressor 32 operates in the heating mode. Thus, additional heat may be generated from the components of the compressor 32.

[0111] When it is determined in step S9 that the estimated component temperature Te is higher than or equal to the first acceptable temperature T1, the controller 100 may determine whether the estimated component temperature Te is lower than a second acceptable temperature "T2" (step S14). The second acceptable temperature T2 refers to a second reference temperature for determining whether each component of the compressor 32 may be damaged due to the generated heat, and the second acceptable temperature T2 may be higher than the first acceptable temperature T1.

[0112] When it is determined at step S14 that the estimated component temperature Te is lower than the second acceptable temperature T2, the controller 100 may maintain the motor portion 32b of the compressor 32 in the current control mode (step S15).

[0113] When it is determined at step S14 that the estimated component temperature Te is higher than or equal to the second acceptable temperature T2, the controller 100 may cancel the heating mode of the compressor 32 (step S16).

[0114] When it is determined in step S2 that the temperature difference between the lowest temperature Tr of the refrigerant and the freezing temperature To of the refrigerant oil contained in the refrigerant (i.e., Tr-To) is higher than or equal to the threshold value "a", the controller 100 may determine whether the estimated component temperature Te is lower than the second acceptable temperature T2 (step S14). Then, steps S15 and S16 may be performed based on the result of step S14.

[0115] When it is determined in step S4 that the maximum heat capacity Hm is greater than or equal to the vehicle required heat Hr, the controller 100 may determine whether the estimated component temperature Te is lower than the second acceptable temperature T2 (step S14). Then, steps S15 and S16 may be performed based on the result of step S14.

[0116] As described above, the HVAC system of the vehicle and the control method thereof according to the embodiment of the present invention can be designed to control the inverter of the compressor in such a way that the motor part of the compressor operates in a loss mode based on the temperature of the refrigerant, the freezing temperature of the refrigerant oil, and the component temperature of the compressor, so that the compressor can operate in a heating mode that generates additional heat from the compressor. Such an HVAC system and method can prevent the freezing of the refrigerant oil and relatively increase the RPM of the compressor, thereby improving the cabin heating performance.

[0117] In the above, although the present invention has been described with reference to the embodiments and the accompanying drawings, the present invention is not limited thereto. On the contrary, the present invention may be variously modified and changed by a person skilled in the art to which the present invention belongs without departing from the spirit and scope of the present invention claimed in the appended claims.

Claims

1. A HVAC system for a vehicle, comprising: A compressor including a compression part, a motor part, and an inverter, the motor part being configured to drive the compression part, the inverter being configured to operate the motor part in any one of an efficiency mode and a loss mode; and A controller is configured to control an inverter of the compressor based on a minimum temperature of the refrigerant and a freezing temperature of refrigerant oil contained in the refrigerant.

2. The HVAC system of a vehicle according to claim 1, wherein: The controller is configured to: when a temperature difference between a minimum temperature of the refrigerant and a freezing temperature of refrigerant oil contained in the refrigerant is lower than a threshold value and a component temperature of the compressor is lower than an acceptable temperature, control an inverter of the compressor to operate in a heating mode; The heat generation mode is a mode in which additional heat is generated from the compressor when the inverter operates the motor portion in a loss mode.

3. The HVAC system for a vehicle according to claim 1, wherein: The controller is configured to: calculate the required heat amount and the maximum heat capacity of the vehicle when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is lower than a threshold value; The maximum heat capacity is the maximum amount of heat transferred from the refrigerant to the vehicle cabin when the HVAC system is operating in heating mode.

4. The HVAC system of a vehicle according to claim 3, wherein: The controller is configured as follows: When the maximum heat capacity is lower than the heat required by the vehicle, selecting a control mode and a control parameter of the motor portion of the compressor based on a difference between the heat required by the vehicle and the maximum heat capacity; calculating heat generated from the compressor based on the selected control mode and control parameters; The component temperature of the compressor is estimated based on the calculated heat amount.

5. The HVAC system for a vehicle according to claim 4, wherein: The controller is configured to control an inverter of the compressor to operate in a heating mode when the estimated component temperature is below an acceptable temperature.

6. The HVAC system for a vehicle according to claim 4, wherein: The controller is configured to estimate vibration and noise levels generated by the compressor and the refrigerant based on the selected control mode and control parameters when the estimated component temperature is below an acceptable temperature.

7. The HVAC system for a vehicle according to claim 6, wherein: The controller is configured to control an inverter of the compressor to operate in a heating mode when vibration and noise levels generated by the compressor and the refrigerant are lower than acceptable vibration and noise levels.

8. A method of controlling an HVAC system of a vehicle, the HVAC system of the vehicle including a compressor having a compression portion, a motor portion configured to drive the compression portion, and an inverter configured to operate the motor portion in either an efficiency mode and a loss mode, the method comprising: Operate the HVAC system in heating mode; The inverter of the compressor is controlled by a controller based on the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant.

9. The method according to claim 8, wherein: The controlling of the inverter includes: when a temperature difference between a minimum temperature of the refrigerant and a freezing temperature of refrigerant oil contained in the refrigerant is lower than a threshold value and a component temperature of the compressor is lower than an acceptable temperature, controlling, by a controller, the inverter of the compressor to operate in a heating mode; The heat generation mode is a mode in which additional heat is generated from the compressor when the inverter operates the motor portion in a loss mode.

10. The method according to claim 8, wherein: The control of the inverter includes: when the temperature difference between the lowest temperature of the refrigerant and the freezing temperature of the refrigerant oil contained in the refrigerant is lower than a threshold value, calculating the required heat amount and the maximum heat capacity of the vehicle by a controller; The maximum heat capacity is the maximum amount of heat transferred from the refrigerant to the vehicle cabin when the HVAC system is operating in heating mode.

11. The method according to claim 10, wherein: The inverter control includes: When the maximum heat capacity is lower than the heat required by the vehicle, the controller selects a control mode and a control parameter of the motor portion of the compressor based on a difference between the heat required by the vehicle and the maximum heat capacity; calculating, by the controller, a heat generated from the compressor based on the selected control mode and control parameters; The temperature of components of the compressor is estimated by the controller based on the calculated heat amount.

12. The method according to claim 11, wherein: The control of the inverter includes: when the estimated component temperature is lower than the acceptable temperature, the controller controls the inverter of the compressor to operate in a heating mode.

13. The method according to claim 11, wherein: The control of the inverter includes estimating, by the controller, vibration and noise levels generated by the compressor and the refrigerant based on the selected control mode and control parameters when the estimated component temperature is below an acceptable temperature.

14. The method according to claim 13, wherein: The control of the inverter includes: when the vibration and noise levels generated by the compressor and the refrigerant are lower than the acceptable vibration and noise levels, the controller controls the inverter of the compressor to operate in the heating mode.

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