KR102764531B1 - Electric vehicle air conditioning system and its control method - Google Patents

Abstract

The present invention relates to an air conditioning system for an electric vehicle, which can minimize a phenomenon in which cooling performance is temporarily reduced due to a sudden change in the refrigerant path when the air conditioning system enters a battery cooling mode while operating in a cooling mode, and a control method thereof. The air conditioning system control method for an electric vehicle according to the present invention is characterized by including: a step of determining a cooling or heating mode according to a user's temperature setting; a step of performing interior cooling by PID controlling a compressor until a difference between a target evaporator temperature according to the user's temperature setting and a current evaporator temperature converges to an error range when the cooling mode is determined; a step of determining whether a request for cooling a battery has been received from a battery control unit; a step of opening an expansion valve directed to a battery chiller and performing battery cooling through the battery chiller when the request for cooling a battery has been determined to have been received, and simultaneously performing PID control of the compressor for a predetermined period of time by adding a specific compensation RPM value corresponding to the cooling load of the battery to the RPM of the compressor currently under PID control; and a step of returning to the original PID control value of the compressor before applying the compensation RPM value when cooling of the battery is completed.

Description

{Electric vehicle air conditioning system and its control method}

The present invention relates to an air conditioning system for an electric vehicle and a method for controlling the same, and more specifically, to an air conditioning system for an electric vehicle and a method for controlling the same, which can minimize a phenomenon in which cooling performance is temporarily reduced due to a sudden change in the refrigerant path when the air conditioning system enters a battery cooling mode while operating in a cooling mode.

As is well known, automobiles are equipped with air conditioning systems to control the temperature of the air inside the car. These automobile air conditioning systems generate heat in the winter to keep the car warm, and generate cold air in the summer to keep the car cool.

A typical automobile air conditioning system sequentially connects a compressor, a condenser, an expansion valve, and an evaporator via refrigerant pipes, and the refrigerant circulates as the compressor is driven by the engine power. In this automobile air conditioning system, refrigerant gas compressed at high temperature and high pressure by the compressor passes through the condenser, exchanges heat with the surrounding air, and is converted into a liquid refrigerant. The liquefied refrigerant passes through a receiver dryer connected to the condenser, removes impurities, and then passes through the expansion valve to change into a low-temperature gas. Then, the vaporized low-temperature refrigerant passes through the evaporator, exchanges heat with the surrounding air, and is cooled. This cooled air is discharged into the automobile interior by the blower, and the low-temperature gas refrigerant that has passed through the evaporator is sent back to the compressor and compressed at high temperature and high pressure, repeating the process.

Meanwhile, electric vehicles that use electric energy as a power source have been released recently, but the air conditioning systems installed in these electric vehicles are configured to heat the interior of the vehicle by heating water or air using power supplied from the battery, which has the disadvantage of significantly reducing the power performance of the electric vehicle.

Accordingly, the air conditioning system of electric vehicles uses a heat pump system similar to that of conventional internal combustion engine vehicles. This heat pump system is a combined cooling and heating system that reversibly applies the cycle of compression-condensation-decompression-evaporation of the refrigerant to provide both cooling and heating.

In other words, since the heat pump system has a circulatory cycle in which the liquid refrigerant evaporates in the evaporator, takes away the surrounding heat and becomes a gas, and then liquefies again in the condenser while releasing the heat to the surroundings, it has the advantage of being able to secure a heat source that is lacking in existing air conditioning systems when applied to electric or hybrid vehicles.

Conventional air conditioning systems for electric vehicles that use a heat pump system like this one have a part of the refrigerant circuit piped to an evaporator located inside an HVAC (Heating Ventilation Air Conditioning System) module located inside the vehicle, and cooled air is obtained through heat exchange between the refrigerant in the evaporator and the air moving around it.

However, when a conventional electric vehicle air conditioning system receives a request for cooling the battery from the Battery Management System (BMS) while operating in cooling mode, the system opens an expansion valve installed on the battery chiller side to supply low-temperature refrigerant that has exchanged heat in an external heat exchanger to the battery chiller side, thereby cooling the battery. However, if the expansion valve installed on the battery chiller side is a solenoid-type expansion valve whose opening amount cannot be controlled, when the system enters battery cooling mode and the expansion valve is opened, some of the refrigerant heading from the external heat exchanger to the internal heat exchanger (evaporator) is rerouted to the battery chiller side, which causes a temporary deterioration in indoor cooling performance.

In order to prevent this temporary decrease in cooling performance that occurs when the battery enters cooling mode, there have been attempts to compensate for the temporary decrease in cooling performance by controlling the RPM of the compressor with PID (Proportional Integral Differential Control) or increasing the flow rate of refrigerant by PID controlling the electronic expansion valve (EEV) installed in the internal heat exchanger (evaporator). However, this method of compensating for the decreased cooling performance by PID controlling the compressor or electronic expansion valve has the problem of accompanying physical limitations. There was also an attempt to compensate for the cooling performance by installing an electronic expansion valve with adjustable opening amount on the battery chiller side, but this method also had the problem of being a burden in terms of cost due to the installation of expensive expansion valves.

Republic of Korea Patent No. 10-2183499 (2020.11.20)

The present invention has been made to solve the above-described conventional problems, and the technical problem to be solved by the present invention is to provide an air conditioning system for an electric vehicle and a control method thereof, which can prevent a phenomenon in which interior cooling performance is temporarily reduced due to a sudden change in the refrigerant path when entering battery cooling mode by adding a compensation RPM value corresponding to the cooling load of the battery to the RPM value of the compressor under PID control and performing PID control of the compressor for a certain period of time when the air conditioning system is operating in cooling mode and a control method thereof.

In order to solve the above-described technical problem, the method for controlling an air conditioning system for an electric vehicle according to the present invention comprises: (a) a step of determining a cooling or heating mode according to a user's temperature setting; (b) a step of performing indoor cooling by PID controlling a compressor until a difference between a target evaporator temperature according to the user's temperature setting and a current evaporator temperature converges to an error range if the mode is determined to be the cooling mode; (c) a step of determining whether a request for cooling a battery has been received from a battery control unit; (d) a step of performing battery cooling through the battery chiller by opening an expansion valve directed to the battery chiller if the request for cooling a battery has been determined to have been received, and simultaneously performing PID control of the compressor for a predetermined period of time by adding a specific compensation RPM value corresponding to the cooling load of the battery to the RPM of the compressor currently under PID control; and (e) a step of returning to the PID control value of the compressor in step (b) if the cooling of the battery is completed.

Here, if it is determined in step (a) that the heating mode is in effect, a step (a-1) of determining whether the outside temperature is within a set range may be further included.

And, if it is determined from the step (a-1) that the outside temperature is within the set range, a step (a-2) of simultaneously performing PID control of the coolant electric heater and the compressor to perform indoor heating may be further included.

The specific compensation RPM value added in the above step (d) can be calculated as a constant ratio value according to the cooling load of the battery.

The above expansion valve may be configured as an expansion valve that is operated ON/OFF in a solenoid manner.

Meanwhile, an air conditioning system for an electric vehicle according to the present invention comprises: a compressor that compresses and discharges a refrigerant; a four-way valve that transfers the refrigerant discharged from the compressor to an external heat exchanger or an internal heat exchanger according to an air conditioning mode; an external heat exchanger that heat-exchanges the refrigerant delivered from the compressor or the internal heat exchanger with air outside the vehicle; an internal heat exchanger that heat-exchanges the refrigerant delivered from the external heat exchanger with air supplied into an HVAC module or the refrigerant discharged from the compressor with air supplied into an HVAC module; an electronic expansion valve that is arranged on a refrigerant line introduced into or discharged from the internal heat exchanger and is capable of controlling the opening amount so as to allow the refrigerant to expand according to the air conditioning mode; a coolant electric heater that is installed inside the HVAC module and heats the air discharged through the internal heat exchanger; A battery chiller mounted between an external heat exchanger and an internal heat exchanger within an HVAC module, and configured to transfer refrigerant discharged from the external heat exchanger to the compressor after heat-exchanging with a battery depending on the air conditioning mode; an expansion valve for opening and closing the flow of refrigerant from the external heat exchanger toward the battery chiller; A control unit which controls the compressor, the cooling water electric heater, and the expansion valve according to the air conditioning mode; The control unit performs indoor cooling by PID controlling the compressor until the difference between the target evaporator temperature according to the user's temperature setting and the current evaporator temperature converges to an error range when the air conditioning mode is operated in the cooling mode, and when a request for cooling the battery is received from the battery control unit, opens the solenoid-type expansion valve directed to the battery chiller to perform battery cooling through the battery chiller, and simultaneously performs PID control of the compressor for a predetermined period of time by adding a specific compensation RPM value corresponding to the cooling load of the battery to the RPM of the compressor currently under PID control, and when the cooling of the battery is completed, returns to the original PID control value of the compressor.

In this case, a specific compensation RPM value added to the PID control of the compressor when cooling the battery can be calculated as a constant ratio value according to the cooling load of the battery.

And, the above expansion valve can be applied as an expansion valve that operates ON/OFF in a solenoid manner.

In addition, the air conditioning system for an electric vehicle according to the present invention may further include an electrical component cooling circuit section which is mounted adjacent to an external heat exchanger and absorbs heat generated from electrical components mounted in the vehicle and discharges it through an electrical component radiator depending on an air conditioning mode, or absorbs the heat and then performs heat exchange with a refrigerant/electrical component coolant heat exchanger; and a refrigerant/electrical component coolant heat exchanger which is mounted between the external heat exchanger and a four-way valve and performs heat exchange between refrigerant discharged from the external heat exchanger and coolant flowing through an electrical component coolant passage.

According to the air conditioning system for an electric vehicle of the present invention and its control method, in an air conditioning system in which indoor air conditioning and battery cooling are performed in a single loop system, when a request for cooling a battery is received from a battery control unit while the air conditioning system is operating in a cooling mode, a specific compensation RPM value corresponding to a battery cooling load is added to the RPM value of a compressor under PID control in the cooling mode to perform high-output PID control of the compressor for a certain period of time, thereby compensating for a temporary decrease in indoor cooling performance due to a sudden change in the refrigerant path in the process of entering the battery cooling mode, thereby providing an advantage in that a comfortable cooling environment can be provided to indoor passengers without discomfort due to a sudden temperature change.

In addition, instead of using an expensive electronic expansion valve (EEV) with adjustable opening for the expansion valve installed on the battery chiller side, a low-cost expansion valve that is only turned on/off by a solenoid is used, thereby compensating for the decrease in indoor cooling performance that occurs when entering battery cooling mode by applying only the simple control logic of the compressor, which has the advantage of reducing the configuration cost of the air conditioning system.

Figure 1 is a schematic diagram showing the configuration of an air conditioning system for an electric vehicle according to the present invention.
Figure 2 is a schematic diagram showing the flow of refrigerant when the air conditioning system is operated in cooling mode.
Figure 3 is a schematic diagram showing the flow of refrigerant when the air conditioning system is operated in heating mode.
Figure 4 is a schematic diagram showing the flow of refrigerant when the air conditioning system is operated simultaneously in cooling mode and battery cooling mode.
Figure 5 is a flow chart showing a control method of an air conditioning system according to the present invention.
Figure 6 is a diagram showing the PID control of the compressor in a mathematical relationship when the air conditioning system is operated in cooling mode.
Figure 7 is a diagram showing the mathematical relationship that compressor PID control is performed by adding a specific compensation RPM value corresponding to the battery cooling load when the air conditioning system enters battery cooling mode while operating in cooling mode.

Below, with reference to the attached drawings, an embodiment of the present invention is described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily practice the present invention.

However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. In addition, it is to be understood that parts denoted by the same reference numerals throughout the detailed description represent the same components.

Hereinafter, an air conditioning system for an electric vehicle and a control method thereof according to an embodiment of the present invention will be described in detail.

Figure 1 is a schematic diagram showing the overall configuration of an air conditioning system for an electric vehicle according to an embodiment of the present invention.

Referring to FIG. 1, an air conditioning system (100) for an electric vehicle according to an embodiment of the present invention is configured to include a compressor (110), a four-way valve (120), an external heat exchanger (130), an internal heat exchanger (140), an electrical component cooling circuit (160), a first expansion valve (170), a battery chiller (190), a second expansion valve (191), which are arranged at specific locations and perform specific roles, and a control unit (Electric HVAC vehicle control unit, EHVCU) that controls the compressor (110), the four-way valve (120), the coolant electric heater (104), and the first and second expansion valves (170, 191) respectively according to an air conditioning mode.

The compressor (110) is configured to compress and discharge refrigerant, and is equipped with an electric compressor capable of PID controlling (Proportional Integral Differential Control) the RPM of the compressor (110) through a control unit.

When the indoor temperature is controlled by the user, the compressor (110) sets the temperature around the internal heat exchanger (140) as a target temperature in the control unit, and performs indoor cooling or heating by PID controlling the compressor (110) through feedback control until the difference between the set target temperature and the current temperature around the internal heat exchanger (140) measured by the temperature sensor converges within a preset error range.

The four-way valve (120) is configured to transfer the refrigerant discharged from the compressor (110) to an external heat exchanger (130) or an internal heat exchanger (140) depending on the air conditioning mode, and can direct the flow of the refrigerant in a specific direction through control of the control unit.

The external heat exchanger (130) has the function of exchanging heat between the refrigerant delivered from the compressor (110) or the internal heat exchanger (140) and the air outside the vehicle, and the internal heat exchanger (140) has the function of exchanging heat between the refrigerant delivered from the external heat exchanger (130) and the air supplied to the interior where the passengers are located, or exchanging heat between the refrigerant discharged from the compressor (110) and the air supplied to the interior.

The first expansion valve (170) is placed on the refrigerant line that is introduced into or discharged from the internal heat exchanger (140), and can be operated according to a control signal transmitted from the control unit to expand the refrigerant. At this time, as the first expansion valve (170) employed in the air conditioning system (100) of the present invention, an electronic expansion valve (EEV) capable of controlling the opening amount by PID control is used.

The electrical component cooling circuit (160) is installed adjacent to the external heat exchanger (130) and has the function of absorbing heat generated from electrical components installed in the vehicle and discharging it to the outside according to the air conditioning mode.

The above-mentioned electrical component cooling circuit (160) is equipped with a refrigerant/electrical component cooling water heat exchanger (161) that is installed between the external heat exchanger (130) and the four-way valve (120) and performs heat exchange between the refrigerant discharged from the external heat exchanger (130) and the cooling water flowing along the electrical component cooling water path (162).

The electrical component coolant passage (162) forms a single coolant flow passage connecting the refrigerant/electrical component coolant heat exchanger (161) and the electrical component radiator (163), and an electrical component cooling means (164) for absorbing heat generated from electrical components mounted on a vehicle and an electrical component coolant circulation pump (165) for generating one-way flow of coolant are mounted on the electrical component coolant bypass passage (167), and a three-way valve (166) for electrical component cooling is mounted at the intersection of the electrical component coolant passage (162) and the electrical component coolant bypass passage (167).

And, the electrical component radiator (163) is installed adjacent to the external heat exchanger (130) to release the heat of the coolant flowing through the electrical component cooling water path (162). At this time, depending on the case, the electrical component cooling circuit (160) can be used to absorb the heat generated from the electrical components mounted on the vehicle and release it only through the electrical component radiator (163), and a separate cooling fan (168) can be installed to promote heat dissipation.

Meanwhile, the four-way valve (120) that directs the flow of refrigerant in a specific direction is configured to include a first port (121), a second port (122), a third port (123), and a fourth port (124).

Specifically, the first port (121) of the four-way valve is a refrigerant inlet through which refrigerant discharged from the compressor (120) is always introduced regardless of the air conditioning mode, and the second port (122) is a refrigerant inlet/outlet that is selectively connected to the first port (121) or the third port (123) depending on the air conditioning mode, and is connected to an internal heat exchanger (140) placed inside the HVAC module (101).

In addition, the third port (123) of the four-way valve is a refrigerant outlet that is selectively connected to the second port (122) and the fourth port (124) depending on the air conditioning mode, and is connected to an intermediate heat exchanger (180) placed in front of the compressor (110) in the refrigerant flow.

In addition, the fourth port (122) of the four-way valve is a refrigerant inlet/outlet that is selectively connected to the first port (121) and the third port (123) depending on the air conditioning mode, and is connected to the refrigerant/electrical component cooling water heat exchanger (111) of the electric component cooling circuit.

In addition, when the first port (121) of each port of the above four-way valve is connected to the second port (122), the third port (123) is connected to the fourth port (124), and when the first port (121) is connected to the fourth port (124), the second port (122) is connected to the third port (123).

Accordingly, when the first port (121) of the four-way valve is connected to the fourth port (124), the refrigerant discharged from the compressor (110) is transferred to the refrigerant/electrical component cooling water heat exchanger (161) of the electrical component cooling circuit (160), and when the fourth port (124) is connected to the third port (123), the refrigerant that has passed through the refrigerant/electrical component cooling water heat exchanger (161) of the electrical component cooling circuit is transferred to the intermediate heat exchanger (180) arranged in front of the compressor (110) in the refrigerant flow.

Meanwhile, a first branch point (181) is provided on the refrigerant line connecting the external heat exchanger (130) and the internal heat exchanger (140) to branch or join the refrigerant discharged from the external heat exchanger (130), and a second branch point (182) is provided on the refrigerant line connecting the third port (123) of the four-way valve (120) and the compressor (110) to branch or join the refrigerant discharged through the four-way valve (120).

At this time, it is preferable to position the second branch point (182) before the intermediate heat exchanger (180) so as to further increase the superheat and performance of the refrigerant coming from the battery chiller (190).

In addition, a battery chiller (190) is mounted on a separate refrigerant branch line connecting the first branch point (181) and the second branch point (182), and depending on the air conditioning mode, the refrigerant discharged from the external heat exchanger (130) can be introduced into the second expansion valve (191) to cool the battery through heat exchange in the battery chiller (190). In this case, a check valve (192) can be mounted on the outlet side piping line of the battery chiller (190) through which the refrigerant is discharged to prevent reverse flow of the refrigerant.

The intermediate heat exchanger (180) is a configuration also abbreviated as IHX (Intermediate Heat Exchanger), and is a configuration provided for heat exchange between the refrigerant before and after passing through the first expansion valve (170) and the internal heat exchanger (140).

This intermediate heat exchanger (180) is installed between the first branch point (181) of the refrigerant line connecting the external heat exchanger (130) and the internal heat exchanger (140) and the external heat exchanger (130), and depending on the air conditioning mode, it heat-exchanges the refrigerant discharged from the external heat exchanger (130) and then transfers it to the internal heat exchanger (140), or heat-exchanges the refrigerant discharged from the internal heat exchanger (140) and then transfers it to the external heat exchanger (130).

In this case, the intermediate heat exchanger (180) may be configured as a double-pipe type heat exchanger including an outer pipe that transfers refrigerant toward the first expansion valve (170) and an inner pipe that transfers refrigerant toward the accumulator (150) and compressor (110). Here, refrigerant having a relatively high pressure and temperature may flow through the outer pipe connected to the first expansion valve (170), and refrigerant having a relatively low pressure and temperature may flow through the inner pipe.

Meanwhile, a heater core (103) into which coolant heated by a coolant electric heater (104) is introduced is mounted inside the HVAC module (101). The heater core (103) is mounted inside an air passage supplied to the interior of a vehicle, and when the air conditioning mode is a heating mode, a dehumidification mode, or a defrost mode, heat is applied to the air supplied to the interior of the vehicle, and the temperature of the coolant supplied to the heater core (103) can be controlled through PID control of the coolant electric heater (104) by a control unit.

The electrical component cooling circuit (160) is controlled to operate when the air conditioning mode of the heat pump system is the heating mode or the cooling mode, and the refrigerant/electrical component cooling water heat exchanger (161) operates as a water-cooled condenser using electrical component cooling water in the cooling mode, and as an evaporator that absorbs heat generated from the electrical component in the heating mode.

Meanwhile, when the air conditioning system (100) is operated in cooling mode, the control unit can perform indoor cooling by PID controlling the compressor (110) until the difference between the target evaporator temperature set by the user through the temperature control device and the current evaporator temperature measured through the temperature sensor converges within the error range.

That is, when the air conditioning system (100) is operated in cooling mode, the internal heat exchanger (140) functions as an evaporator, and the control unit sets the temperature of the internal heat exchanger (140) to the target evaporator temperature according to the temperature set by the user, and performs PID control on the RPM of the compressor (110) until the difference between the current evaporator temperature detected by a temperature sensor (not shown) installed around the internal heat exchanger (140) and the target evaporator temperature converges to a preset error range, thereby performing indoor cooling.

Meanwhile, when the battery (194) is overheated above the set temperature while indoor cooling is being performed by the PID control of the compressor (110) and a request for cooling the battery (194) is received from the battery management system (BMS), the control unit transmits a control signal to open the second expansion valve (191) located on the battery chiller (190) side so that low-temperature refrigerant is supplied to the battery chiller (190), thereby allowing cooling of the battery (194) through the heat exchange action of the battery chiller (190).

In this case, since the second expansion valve (191) installed in the previous position of the battery chiller (190) uses a low-cost expansion valve that can only open/close ON/OFF in a solenoid manner, unlike the first expansion valve (170) described above, when a battery cooling request is received and the second expansion valve (191) is opened, some of the refrigerant supplied from the external heat exchanger (130) to the internal heat exchanger (140) flows into the battery chiller (190), and the amount of refrigerant directed to the internal heat exchanger (140) is rapidly reduced, which may cause a temporary reduction in indoor cooling performance.

In order to compensate for this, in the present invention, when a request for battery cooling comes in during operation in cooling mode and the system enters battery cooling mode, the control unit opens the second expansion valve (191) to perform battery cooling, and at the same time, a specific compensation RPM value corresponding to the cooling load of the battery (194) (total capacity of the battery pack) is added to the RPM of the compressor (110) currently under PID control, that is, a preset specific compensation RPM value capable of compensating for the cooling load of the battery (194), thereby controlling the compressor (110) to perform PID control at high output for a certain period of time, thereby compensating for the phenomenon of indoor cooling performance degradation due to a sudden change in refrigerant when the second expansion valve (191) is opened.

At this time, when entering the battery cooling mode as described above, the battery control unit (BMS) may transmit a preset compensation RPM value that can compensate for the battery (194) cooling load to the compressor (110), and perform PID control of the compressor (110) at high output for a certain period of time through the added compensation RPM value.

And, when the cooling of the battery (194) is completed, the control unit closes the second expansion valve (191) to induce the flow of refrigerant toward the internal heat exchanger (140) and simultaneously controls the PID control value (RPM value) of the compressor (110) currently being controlled to return to its original state (operation only in cooling mode), thereby preventing a rapid temperature drop in the room due to the return of the refrigerant path and reducing power consumption other than for the high-output operation of the compressor (110).

Below, each air conditioning mode of the air conditioning system for an electric vehicle according to the present invention will be described in detail.

FIGS. 2 to 4 illustrate refrigerant circulation flow diagrams showing refrigerant flows in each of the cooling mode, heating mode, cooling mode, and battery cooling mode of an air conditioning system for an electric vehicle according to an embodiment of the present invention.

First, we will explain the cooling mode illustrated in Fig. 2.

In cooling mode, the flow of refrigerant is controlled to flow in the following order: "compressor (110) - 4-way valve (120) - electrical component cooling circuit (160, refrigerant/electrical component cooling water heat exchanger (161) functions as a water-cooled condenser) - external heat exchanger (130, functions as a condenser) - intermediate heat exchanger (180) - internal heat exchanger (140, functions as an evaporator) - 4-way valve (120) - accumulator (150) - compressor (110)".

In cooling mode, the first port (121) of the four-way valve (120) is connected to the fourth port (124) and the second port (122) is connected to the third port (123) so that the refrigerant discharged from the compressor (110) is introduced into the external heat exchanger (130) and the refrigerant discharged from the internal heat exchanger (140) is introduced into the compressor (110).

And, the internal heat exchanger (140) exchanges heat with the refrigerant delivered from the external heat exchanger (130) depending on the air conditioning mode, or exchanges heat with the refrigerant discharged from the compressor (110) with the air supplied to the interior of the vehicle.

Specifically, one port of the internal heat exchanger (140) functions as a passage through which refrigerant that absorbs heat from air introduced into the HVAC module (101) depending on the air conditioning mode is discharged or refrigerant that provides heat to air supplied to the interior of a vehicle is introduced, and the other port functions as a passage through which refrigerant that absorbs heat from air introduced into the HVAC module (101) depending on the air conditioning mode is introduced or refrigerant that provides heat to air supplied to the interior of a vehicle is discharged.

Here, when the air conditioning mode is operated in the cooling mode, the internal heat exchanger (140) functions as an evaporator. The refrigerant delivered from the external heat exchanger (130) is expanded in the first expansion valve (170) and then introduced into the internal heat exchanger (140) in a low-temperature state to exchange heat with the air supplied to the vehicle interior.

The accumulator (150) is installed between the intermediate heat exchanger (180) and the compressor (110), absorbs the refrigerant discharged from the internal heat exchanger (140) through the four-way valve (120), and then delivers it to the compressor (110).

In addition, the electrical component cooling circuit (160) can be operated when the air conditioning mode is the cooling mode, and in this case, the refrigerant/electrical component cooling water heat exchanger (161) operates as a water-cooled condenser using the electrical component cooling water, thereby further cooling the refrigerant inside the refrigerant/electrical component cooling water heat exchanger (161), thereby improving the cooling performance.

Here, the cooling mode shown in Fig. 2 is an operation mode under outside temperature conditions where battery cooling is not required, and the second expansion valve (191) is closed to prevent the battery cooling path branched from the outlet side refrigerant line of the intermediate heat exchanger (180) from opening, thereby preventing the refrigerant from flowing to the battery chiller (190).

Next, the heating mode of the present invention will be described with reference to Fig. 3.

In heating mode, the flow of refrigerant can be controlled to flow in the following order: "compressor (110) - 4-way valve (120) - internal heat exchanger (140, functioning as a condenser) - external heat exchanger (130, functioning as an evaporator) - electrical component cooling circuit (160, refrigerant/electrical component cooling water heat exchanger (161) functioning as an evaporator) - 4-way valve (120) - accumulator (150) - compressor (110)".

The first port (121) of the four-way valve (120) can be communicated with the second port (122), and the third port (122) can be communicated with the fourth port (123) so that the refrigerant discharged from the compressor (110) flows into the internal heat exchanger (140), and the refrigerant discharged from the external heat exchanger (130) flows into the compressor (110).

When operated in heating mode in this manner, the internal heat exchanger (140) functions as a condenser, and the refrigerant discharged from the compressor (110) is introduced into the internal heat exchanger (140) so that the refrigerant can be condensed and heat exchanged with the air supplied to the interior of the vehicle.

In addition, the heating performance can be improved by operating the coolant electric heater (104) so as to heat the air supplied to the interior of the vehicle. At this time, as shown in Fig. 3, a heater core (103) is placed in the HVAC module (101), and a coolant line circulating through the heater core (103) is configured, and a coolant electric heater (104), a pump (105), and a coolant reservoir tank (106) can be placed on the coolant line.

In this case, the accumulator (150) can absorb the refrigerant discharged from the electrical component cooling circuit (160) through the four-way valve (120) and then transfer it to the compressor (110). In addition, in the electrical component cooling circuit (160), the refrigerant discharged from the external heat exchanger (130) can absorb the heat generated from the electrical components mounted on the vehicle through heat exchange, and the refrigerant that has absorbed the heat can be transferred to the accumulator (150) through the four-way valve (120).

In cases where this type of heating mode is operated, such as in winter when the outdoor temperature is low, there is no need to cool the battery in general cases, so the second expansion valve (191) is closed to prevent the refrigerant from flowing toward the battery chiller (190).

At this time, if battery cooling is required due to an abnormality in the battery itself or its surroundings, the battery is cooled by switching to a battery cooling mode that only performs battery cooling, and heating can be performed only by a coolant electric heater (104).

In addition, when the vehicle is running, heat is generated in the electrical components, and when refrigerant flows into the electrical components cooling circuit (160), the refrigerant/electrical components coolant heat exchanger (161) of the electrical components cooling circuit (160) functions as an evaporator, so that the refrigerant absorbs the heat generated in the electrical components and reaches a relatively higher temperature before flowing into the accumulator (150) and compressor side, thereby increasing the amount of heat generated in the internal heat exchanger (140), thereby further improving heating performance.

Meanwhile, when the air conditioning system (100) operates in a cooling mode as in the aforementioned FIG. 2 and then switches to a heating mode as in FIG. 3 as needed, the internal heat exchanger (140) functions as an evaporator in the cooling mode and then changes to a condenser in the heating mode, which may cause a flash fogging phenomenon in which water droplets (moisture) accumulated in the internal heat exchanger (140) evaporate and form on the vehicle windshield.

In the case of an air conditioning system (100) using a 4-way valve (120) like this, when the system is operated in cooling mode and then switched to heating mode, the moisture contained in the internal heat exchanger (140) in the evaporator state evaporates and forms a flash fogging phenomenon on the window, so it was not possible to actively apply a heat pump system with a 4-way valve (120) to a vehicle in the past.

However, in order to solve the flash fogging phenomenon occurring in a heat pump system to which a 4-way valve (120) is applied as described above, in the present invention, when the internal heat exchanger (140) is used as an evaporator and then switched to a condenser by a user or other operating conditions, an operation to dry the internal heat exchanger (140) can be performed by entering a separately set mode called 'Inner HEX dry mode' before being used as a condenser or during a battery reset stage.

In the above internal heat exchanger drying mode, for example, in step 1, the heater core (103) located inside the HVAC module (101) can be driven to perform dehumidification of the internal heat exchanger (140) and indoor heating for a certain period of time. At this time, in step 1, the blower fan (102) provided inside the HVAC module (101) can be driven in two or more stages to assist the dehumidification of the internal heat exchanger (140). In addition, in step 2, the compressor (110) operated in heating mode can be operated at the minimum RPM for a certain period of time to remove residual moisture in the internal heat exchanger (140).

In this case, when the air conditioning system (100) is operated in the internal heat exchanger drying mode as described above and is operated by the user in the defrost (DEF) or air conditioning (A/C) mode (cooling mode), or when the air conditioning system (100) is turned off, the operation of the internal heat exchanger drying mode can be stopped.

In this way, when the air conditioning system (100) switches from cooling mode to heating mode, or enters the internal heat exchanger drying mode when the battery is reset, the internal heat exchanger (140) is naturally dried for a certain period of time using only the heater core (103) in the first step, and the remaining moisture in the internal heat exchanger (140) is removed by operating the compressor (110) at the minimum RPM for a certain period of time in the heat pump mode (heating mode) in the second step, thereby completely drying the internal heat exchanger (140), and when the drying operation of the internal heat exchanger (140) is completely completed, the system is operated in the heating mode (heat pump mode) so as to operate normally, thereby effectively suppressing the phenomenon of flash fogging occurring on the vehicle's windows.

Next, with reference to FIG. 4, a description will be given of a case where the cooling mode and battery cooling mode of the air conditioning system according to the present invention are simultaneously implemented.

When the cooling mode and the battery cooling mode are performed simultaneously, the flow of the refrigerant is controlled to flow in the order of "compressor (110) - 4-way valve (120) - electrical component cooling circuit (160, refrigerant/electrical component cooling water heat exchanger (161) functions as a water-cooled condenser) - external heat exchanger (130, functions as a condenser) - intermediate heat exchanger (180) - internal heat exchanger (140, functions as an evaporator) - 4-way valve (120) - accumulator (150) - compressor (110)", and the refrigerant line connecting the intermediate heat exchanger (180) and the internal heat exchanger (140) can be branched so that a portion of the branched refrigerant can flow into the battery chiller (190) through the second expansion valve (191) to cool the battery.

Here, when the air conditioning system is operated in cooling mode, the internal heat exchanger (140) functions as an evaporator, and the refrigerant delivered from the external heat exchanger (130) is expanded through the first expansion valve (170) and then flows into the indoor heat exchanger (140) to exchange heat with the air supplied to the vehicle interior.

And, the accumulator (150) mounted between the intermediate heat exchanger (180) and the compressor (110) receives the refrigerant discharged from the internal heat exchanger (140) through the four-way valve (120) and then transfers it back to the compressor (110).

Meanwhile, the refrigerant discharged from the external heat exchanger (130) is expanded through the second expansion valve (191) to reach a low temperature state and then introduced into the battery chiller (190) to cool the battery (194) through heat exchange with the cooling water circulating in the battery (194).

In this case, a coolant circulation pump (193), a battery (194), and a battery heater (195) are sequentially arranged in a battery cooling/heating coolant circuit that exchanges heat with a battery chiller (190) to achieve coolant circulation, and the battery chiller (190) performs the role of an evaporator.

In this way, the refrigerant condensed while passing through the external heat exchanger (130) expands through the first expansion valve (170) and the second expansion valve (191) and flows into the internal heat exchanger (140) and the battery chiller (190) as low-temperature refrigerant, thereby cooling the air flowing into the HVAC module (101) and performing indoor cooling, and at the same time, the battery (194) can be cooled by the heat exchange action of the low-temperature refrigerant flowing into the battery chiller (190). Then, the refrigerant that has undergone heat exchange in the battery chiller (190) passes through the internal heat exchanger (140) and the refrigerant that has passed through the four-way valve (120) at the second branch point (182) and flows into the intermediate heat exchanger (181).

In this way, the cooling mode is operated during the summer season when the outdoor temperature is high, and the temperature of the battery (194) rises, thereby reducing battery efficiency. Therefore, the second expansion valve (191) is opened to allow the refrigerant to flow, but the refrigerant is expanded, and the expanded refrigerant passes through the battery chiller (190) that functions as an evaporator, thereby cooling the coolant in the battery cooling and heating coolant circuit. This coolant is circulated to the cooling plate of the battery pack, thereby preventing the battery pack from overheating.

Meanwhile, battery cooling can be performed simultaneously with indoor cooling when a battery cooling request signal is received from the battery management system (BMS) when the battery (194) is overheated above the set temperature. That is, when a battery cooling request is received from the battery management system while the air conditioning system (100) is operating in cooling mode, the management system transmits a control signal to open the second expansion valve (191) located on the battery chiller (190) side and supply low-temperature refrigerant to the battery chiller (190) to perform battery cooling.

In this case, the second expansion valve (191) located on the battery chiller (190) side is an expansion valve that can only be opened and closed by a solenoid (ON/OFF) method and cannot be opened and closed by adjusting the opening amount, unlike the electronic first expansion valve (170) located on the internal heat exchanger (140) side that can control the opening amount. Therefore, when the second expansion valve (191) is opened by entering the battery cooling mode, a portion of the refrigerant flow rate delivered from the external heat exchanger (130) flows into the battery chiller (190) side, and thus the refrigerant flow rate toward the internal heat exchanger (140) side is temporarily reduced, which may cause a problem in that the indoor cooling performance is temporarily reduced.

Accordingly, when a battery cooling request is received while the air conditioning system (100) is operating in cooling mode and enters cooling mode, the control unit opens the second expansion valve (191) to perform battery cooling through the battery chiller (190), and at the same time, adds a specific compensation RPM value corresponding to the cooling load of the battery (194) to the RPM value of the compressor (110) currently under PID control in cooling mode, thereby performing PID control of the compressor (110) at high output for a certain period of time, thereby compensating for a temporary decrease in indoor cooling performance due to a sudden change in the refrigerant path when the second expansion valve (191) is opened.

And, when the cooling of the battery is completed, the control unit closes the second expansion valve (191) to induce the flow of refrigerant only towards the internal heat exchanger (140). In this case, since the compressor (110) operates at high output with a specific compensation RPM value applied in the battery cooling mode, the amount of refrigerant continuously increases, which may cause excessive indoor cooling.

Accordingly, when cooling of the battery is terminated, the control unit applies the current compensation RPM value to control the PID control value of the compressor (110) under high-output PID control to return to the original state (state of operation only in cooling mode), thereby reducing the amount of refrigerant directed to the evaporator, thereby minimizing the phenomenon of rapid temperature drop in the room due to return of the refrigerant path, and also reducing other power consumption for high-output operation of the compressor (110).

Meanwhile, Fig. 5 is a flow chart showing a control method of an air conditioning system according to the present invention. In addition, Fig. 6 is a diagram showing a PID control of a compressor in a mathematical relationship when the air conditioning system is operated only in a cooling mode, and Fig. 7 is a diagram showing a PID control of a compressor RPM with a specific compensation RPM value corresponding to the cooling load of the battery added when the air conditioning system enters a battery cooling mode while operating in a cooling mode.

Referring to FIGS. 5 to 7, the control method of the air conditioning system according to the present invention first determines in the control unit of the air conditioning system (100) whether the current air conditioning system (100) is operating in cooling mode (AC ON) or heating mode (HEAT ON). (S210)

Here, if it is determined from the above step (S210) that the current air conditioning system (100) is operating in heating mode, it is determined whether the current outside temperature of the vehicle is within the set range (S212).

At this time, if the current outside temperature is outside the set range, only the coolant electric heater (104) is PID controlled to perform indoor heating (S214), and if the outside temperature is within the set range, the compressor (110) of the heat pump is PID controlled (S216) in parallel with the PID control (S214) of the coolant electric heater (104) to perform indoor heating.

Meanwhile, if it is determined from the above step (S210) that the current air conditioning system (100) is operating in cooling mode, it is determined whether a request for cooling the battery has been received from the battery management system (BMS). (S220)

At this time, if a battery cooling request is not received, the compressor (110) is PID controlled until the difference between the target evaporator temperature according to the user's indoor temperature setting and the current evaporator temperature converges to the set error range, thereby performing indoor cooling (S222). In this way, the equation related to the PID control of the compressor (110) when the air conditioning system (100) is operated only in the cooling mode is shown in the diagram illustrated in Fig. 6.

On the other hand, if it is determined that a request for cooling the battery has been received in the step (S220), the control unit transmits a control signal to the second expansion valve (191) to open the second expansion valve (191) and introduce low-temperature refrigerant into the battery chiller (190) to cool the battery, and at the same time, adds a specific compensation RPM value corresponding to the cooling load of the battery to the RPM value of the compressor (110) currently under PID control in the cooling mode, and performs PID control of the compressor (110) at high output for a certain period of time. (S230)

The diagram illustrated in FIG. 7 shows a mathematical relationship for PID controlling the compressor (110) by adding a specific compensation RPM value corresponding to the battery cooling load after entering the battery cooling mode in the step (S230).

In this way, when a request for cooling of the battery comes in while the air conditioning system (100) is operating in cooling mode and enters the battery cooling mode, the second expansion valve (191) is opened to perform battery cooling through the battery chiller (190), and at the same time, a specific compensation RPM value corresponding to the cooling load of the battery is added to the RPM value of the compressor (110) currently under PID control in cooling mode, thereby controlling the compressor (110) to perform PID control at high output for a certain period of time, thereby increasing the amount of refrigerant directed to the internal heat exchanger (140) for a certain period of time, thereby effectively compensating for the temporary deterioration of indoor cooling performance due to a sudden change in the refrigerant path caused by the opening of the second expansion valve (191).

And, when the battery cooling is completed, the control unit closes the second expansion valve (191) in the open state to induce the flow of refrigerant back toward the internal heat exchanger (140), and at the same time, controls the PID control value (RPM value) of the compressor (110) currently under PID control with the compensated RPM value to return to the original state (state of operation only in cooling mode), thereby preventing a rapid temperature drop inside the vehicle due to the return of the refrigerant path to the original state, and reducing power consumption due to temporary high-output operation of the compressor (110).

In an actual experiment related to the present invention, when the air conditioning system (100) was operating in cooling mode and entered battery cooling mode, a phenomenon occurred in which the temperature change of the air discharged into the vehicle interior temporarily decreased by about 10 degrees due to a sudden change in the refrigerant path. However, when the air conditioning system control method of the present invention was applied, it was confirmed that the temperature change of the discharged air decreased to less than 5 degrees.

In addition, it can be confirmed that the indoor discharge air temperature does not drop excessively as the PID control value (RPM value) of the compressor (110) currently being controlled at high output returns to the control value of the original state (state of operation only in cooling mode) at the time when battery cooling is terminated.

In this way, when a battery cooling request comes in while the vehicle's air conditioning system is operating in cooling mode and the vehicle enters battery cooling mode at an initial point in time, a specific compensation RPM value corresponding to the battery cooling load (total capacity of the battery pack) is added to the RPM value of the compressor (110) currently under PID control in cooling mode, thereby controlling the compressor (110) to perform PID control at high output, thereby minimizing the phenomenon of temporary deterioration of interior cooling performance due to a sudden change in the refrigerant path when entering battery cooling mode, and thereby creating a comfortable interior environment for interior passengers without discomfort caused by a decrease in interior cooling temperature.

In addition, by controlling the PID control value of the compressor (110) that is currently under high output PID control at the currently compensated RPM value at the time when cooling of the battery is completed to return to the original state, a rapid temperature drop inside the vehicle due to the return of the refrigerant path can be prevented, and power consumption due to high output operation of the compressor (110) can be reduced.

Although the preferred embodiments of the present invention have been described above, the scope of the present invention is not limited to these specific embodiments, and those skilled in the art will be able to make appropriate changes within the scope described in the claims of the present invention.

100 : Air Conditioning Systems 101 : HVAC Modules
102: Blower fan 103: Heater core
104: Coolant electric heater 110: Compressor
120: 4-way valve 130: External heat exchanger
140: Internal heat exchanger 150: Accumulator
160: Cooling circuit for the entire body 170: First expansion valve
180: Intermediate heat exchanger 190: Battery chiller
191: Second expansion valve 194: Battery

Claims (9)

(a) a step of determining a cooling or heating mode based on the user's temperature setting;
(b) a step of performing indoor cooling by PID controlling the compressor until the difference between the target evaporator temperature according to the user's temperature setting and the current evaporator temperature converges within the error range when the cooling mode is determined;
(c) a step of determining whether a request for cooling the battery has been received from the battery control unit;
(d) When it is determined that a request for cooling of the battery has been received, the expansion valve directed to the battery chiller is opened to perform cooling of the battery through the battery chiller, and at the same time, a specific compensation RPM value corresponding to the cooling load of the battery is added to the RPM of the compressor currently under PID control to perform PID control of the compressor for a certain period of time.
A step of performing indoor cooling by PID controlling the compressor (110) until the difference between the target evaporator temperature according to the user's indoor temperature setting and the current evaporator temperature converges to a set error range when it is determined that a battery cooling request has not been received;
(e) a step of returning to the PID control value of the compressor of step (b) when cooling of the battery is completed;
(f) a step of switching from cooling mode to heating mode, or entering the internal heat exchanger drying mode when the battery is reset, and naturally drying the internal heat exchanger (140) with only the heater core (103) for a certain period of time, and a step of operating the compressor (110) in heating mode at a minimum RPM for a certain period of time to remove residual moisture in the internal heat exchanger (140), thereby completely drying the internal heat exchanger (140), and operating it so that it operates normally in heating mode when the drying operation of the internal heat exchanger (140) is completely completed;
A method for controlling an air conditioning system of an electric vehicle, characterized by including a.
A method for controlling an air conditioning system of an electric vehicle, characterized in that in the first paragraph, if it is determined in step (a) that the heating mode is in effect, the method further comprises a step (a-1) of determining whether the outside temperature is within a set range.
In the second paragraph, a method for controlling an air conditioning system of an electric vehicle, characterized in that the method further includes a step (a-2) of simultaneously performing PID control of a coolant electric heater and a compressor to perform indoor heating if the outside temperature is determined to be within a set range from the step (a-1).
A method for controlling an air conditioning system of an electric vehicle, characterized in that in the first paragraph, the specific compensation RPM value added in the step (d) is calculated as a constant ratio value according to the cooling load of the battery.
A method for controlling an air conditioning system of an electric vehicle, characterized in that in the first paragraph, the expansion valve is an expansion valve that is turned on/off in a solenoid manner.
A compressor that compresses and discharges refrigerant;
A four-way valve that transfers the refrigerant discharged from the compressor to an external heat exchanger or an internal heat exchanger depending on the air conditioning mode;
An external heat exchanger that exchanges heat between the refrigerant delivered from the compressor or internal heat exchanger and the air outside the vehicle;
An internal heat exchanger that heat-exchanges the refrigerant delivered from the external heat exchanger with the air supplied into the HVAC module, or heat-exchanges the refrigerant discharged from the compressor with the air supplied into the HVAC module;
An electronic expansion valve capable of controlling the opening amount, which is arranged on a refrigerant line introduced into or discharged from the internal heat exchanger and is provided to allow the refrigerant to expand according to the air conditioning mode;
A cooling water electric heater installed inside the HVAC module and heating the air discharged through the internal heat exchanger;
A battery chiller mounted between an external heat exchanger and an internal heat exchanger within an HVAC module, configured to transfer refrigerant discharged from the external heat exchanger to the compressor after heat-exchanging it with a battery depending on the air conditioning mode;
An expansion valve that opens and closes the flow of refrigerant from the external heat exchanger toward the battery chiller;
It includes a control unit that controls the compressor, the cooling water electric heater, and the expansion valve according to the air conditioning mode;
In the battery cooling and heating coolant circuit that exchanges heat with the above battery chiller, a coolant circulation pump, a battery, and a battery heater are sequentially arranged to circulate the coolant.
A first branch point is provided on the refrigerant line connecting the external heat exchanger and the internal heat exchanger, where the refrigerant discharged from the external heat exchanger branches or joins, and a second branch point is provided on the refrigerant line connecting the third port of the four-way valve and the compressor, where the refrigerant discharged through the four-way valve branches or joins.
The above second branch point is located before the intermediate heat exchanger,
The above control unit,
When the air conditioning mode is operated in cooling mode, the compressor is PID controlled to perform indoor cooling until the difference between the target evaporator temperature according to the user's temperature setting and the current evaporator temperature converges to the error range.
When a request for cooling the battery is received from the battery control unit, a solenoid-type expansion valve directed to the battery chiller is opened to perform cooling of the battery through the battery chiller, and at the same time, a specific compensation RPM value corresponding to the cooling load of the battery is added to the RPM of the compressor currently under PID control to perform PID control of the compressor for a certain period of time, and when the cooling of the battery is completed, the control is performed to return to the original PID control value of the compressor.
An air conditioning system for an electric vehicle characterized in that it operates in the following steps: a first step of naturally drying the internal heat exchanger using only a heater core for a predetermined period of time by switching from cooling mode to heating mode or entering the internal heat exchanger drying mode when the battery is reset; a second step of operating the compressor (110) in heat pump mode at a minimum RPM for a predetermined period of time to remove any remaining moisture in the internal heat exchanger; and when the drying operation of the internal heat exchanger is completely completed, it operates in the heating mode to operate normally.
An air conditioning system for an electric vehicle, characterized in that in claim 6, a specific compensation RPM value added to the PID control of the compressor when cooling the battery is calculated as a constant ratio value according to the cooling load of the battery.
An air conditioning system for an electric vehicle, characterized in that in claim 6, the expansion valve is an expansion valve that is turned on/off in a solenoid manner.
In the 6th paragraph, an electrical component cooling circuit section which is mounted adjacent to the external heat exchanger and absorbs heat generated from electrical components mounted in the vehicle according to the air conditioning mode and releases the heat through an electrical component radiator or performs heat exchange with a refrigerant/electrical component coolant heat exchanger after absorbing the heat; and
A refrigerant/electrical component cooling water heat exchanger installed between the external heat exchanger and the four-way valve, and exchanging heat between the refrigerant discharged from the external heat exchanger and the cooling water flowing through the electric component cooling water passage;
An air conditioning system for an electric vehicle, characterized by further including: