KR102018764B1 - Heat pump system and control method thereof - Google Patents

Abstract

The present invention relates to a heat pump system and a control method thereof, which can prevent the motor compressor from being stopped due to overload by rotating the motor at a constant speed under high pressure conditions based on the motor phase current and the discharge pressure of the motor compressor. The pump system includes an electric valve, a condenser connected to an outlet of the electric compressor having a first heat exchanger, an evaporator connected to an inlet of the electric compressor with a second heat exchanger, and an expansion valve provided in the middle of a refrigerant pipe connecting the condenser and the evaporator. A pressure sensor for detecting the discharge pressure of the discharge port of the electric compressor, and a power range below the power determined by the calculated torque and the speed of the motor in operation when the discharge pressure detected by the pressure sensor is greater than a predetermined reference pressure. Inverter controller for driving and controlling the motor in the.

Description

Heat pump system and its control method {HEAT PUMP SYSTEM AND CONTROL METHOD THEREOF}

The present invention relates to a heat pump system and a control method thereof, and more particularly, to stop the electric compressor from being stopped due to overload by rotating the motor at a constant speed under high pressure conditions based on the motor phase current and the discharge pressure of the electric compressor. A heat pump system that can be prevented and a control method thereof.

In the case of an air conditioning system equipped with a heat pump system, Full Automatic Temperature Control (FATC) determines the air conditioning mode and the heating mode according to the ambient temperature and the user's instruction, and controls the system valves and the electric compressor. do.

Here, in the vehicle heat pump system, the outdoor unit serves as an evaporator, and it is common to use an internal indoor condenser. A motor-driven compressor is a device that drives a compressor by a motor to compress a fluid. An inverter-integrated motor-compressor, which is a kind of motor-driven compressor, is a device that integrates an inverter for controlling a motor into a motor-compressor, and is used in a vehicle air conditioning system and the like. .

In the vehicle air conditioning system, when the heating mode is driven, excessive torque through the scroll compression unit is applied to the electric compressor due to the high pressure discharge pressure generated in the indoor condenser. As a result, excessive torque causes the electric compressor to be overloaded, and an overcurrent occurs in the motor driving the motor-overloaded compressor.

The relationship between the torque and the current in the motor is expressed by Equation 1 below.

In Equation 1, T represents torque, kt represents torque constant of the motor, and I represents phase current of the motor, respectively.

When the phase current of the motor reaches the limit current of the inverter, the inverter of the motor-compressor stops the operation of the motor-compressor for self-protection (prevention of damage to the inverter due to overcurrent).

As described above, when the operation of the electric compressor is stopped in the air conditioning system equipped with the conventional heat pump system, since the refrigerant cannot be compressed properly, the heating mode cannot be properly used in a device or facility such as a vehicle. This may cause a problem that the operation of the electric compressor is stopped.

In particular, in vehicles such as electric vehicles, fuel cell vehicles, and hybrid vehicles, the operating atmosphere of the electric motor or fuel cell stack can be maintained through the heat pump system. In this case, if the heat pump system is not operating properly, It is not possible to adequately preheat and supply reactants (air, etc.) such as this, which may cause the output of the fuel cell stack to become unstable, greatly reducing the efficiency of the device or disturbing the normal operation of the vehicle. There is.

Republic of Korea Patent Publication No. 10-2009-0062750 (2009.06.17)

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and provides a heat pump system and a method of controlling the same in which a current of more than a limit current flows to the inverter in the low speed and high load mode of the motor compressor to prevent the operation of the motor compressor to stop. It aims to do it.

The present invention also provides a heat pump system and a method of controlling the same, which can prevent the motor compressor from shutting down due to overload by rotating the motor at a constant speed under high pressure conditions based on the motor phase current and the discharge pressure of the motor compressor. The purpose.

(T는 토크, kt는 모터의 토크 상수, 그리고 I는 모터의 상전류)을 통해 산출된 토크와 작동중인 모터의 속도에 의해 결정되는 파워 이하의 파워 영역에서 모터를 구동 및 제어하는 제어기를 포함한다.In order to solve the above technical problem, the heat pump system according to the present invention, an electric compressor; A condenser connected to an outlet of the electric compressor having a first heat exchanger; An evaporator having a second heat exchanger and connected to an inlet of the electric compressor; An expansion valve provided in the middle of the refrigerant pipe connecting the condenser and the evaporator; A pressure sensor detecting a discharge pressure of the discharge port of the electric compressor; And when the discharge pressure detected through the pressure sensor is greater than a predetermined reference pressure,

A controller for driving and controlling the motor in a power region below the power determined by the torque calculated from (T is the torque, kt is the torque constant of the motor, and I is the motor's phase current) and the speed of the motor in operation. .

In one embodiment, the motorized compressor comprises a scroll compressor.

In one embodiment, the pressure sensor comprises an Automotive Pressure Transducer (APT) sensor.

In one embodiment, the inverter controller receives a mode signal corresponding to the discharge pressure and the operating mode of the heat pump system from the full automatic temperature control (FATC). Here, the FATC may receive and store the discharge pressure from an engine control unit (ECU) of an electric vehicle or a hybrid vehicle connected to the APT sensor.

In one embodiment, the inverter controller, the heating mode determination unit for determining the heating mode based on the mode signal from the FATC; A speed controller for driving and controlling the motor based on the speed feedback in the air conditioner mode; A discharge pressure receiver for receiving a discharge pressure of the electric compressor from the FATC in the heating mode; A comparison unit comparing the discharge pressure with a preset reference pressure; And a power control unit for driving and controlling the motor in a power region below the power determined by the calculated torque and the speed of the motor in operation when the discharge pressure is greater than the reference pressure.

을 통해 산출된 토크와 작동중인 모터의 속도에 의해 결정되는 파워 이하의 파워 영역에서 모터를 구동 및 제어하는 단계를 포함한다.A control method of a heat pump system according to the present invention includes determining whether the heat pump system is in a heating mode on the basis of a mode signal input from the outside in an inverter controller of an electric compressor of an electric vehicle or a hybrid vehicle; If the heat pump system is in heating mode, receiving a discharge pressure of the motor-driven compressor of the heat pump system; Comparing the discharge pressure with a preset reference pressure; If the discharge pressure is greater than the reference pressure, the formula

And driving and controlling the motor in a power region that is less than or equal to the power determined by the torque and the speed of the motor in operation.

In one embodiment, the method of controlling the heat pump system further comprises speed controlling the motor. Here, the speed control of the motor may be performed when the heat pump system is in an air conditioner mode instead of the heating mode, as a result of the determination in the step of determining whether the heat pump system is the heating mode. In addition, the step of controlling the speed of the motor may be performed when the discharge pressure is equal to or smaller than the reference pressure in the step of comparing the discharge pressure with the reference pressure.

In one embodiment, receiving the discharge pressure of the motor-driven compressor includes the inverter controller receiving the mode signal and the discharge pressure from a full automatic temperature control (FATC). Here, the FATC may receive and store the discharge pressure from an engine control unit (ECU) connected to an APT (Automotive Pressure Transducer) sensor.

The heat pump system and control method thereof according to the present invention provide an effect of preventing the operation of the motor-compressor due to a current exceeding a limit current flowing through the inverter in the low-speed, high-load mode of the motor-compressor.

In addition, the heat pump system and the control method according to an embodiment of the present invention, by rotating the motor at a constant speed under high pressure conditions based on the motor phase current and the discharge pressure of the motor compressor to prevent the motor compressor from stopping operation due to overload. It provides an effect that can be done.

1 is a schematic diagram of a heat pump system according to the present invention;
FIG. 2 is a block diagram illustrating a schematic configuration of a motor-driven compressor of the heat pump system of FIG. 1 and a connection relationship between a full automatic temperature control (FATC) and an ECU.
3 is a block diagram schematically showing the configuration of the inverter controller of FIG.
4 is a flow chart of a control method of a heat pump system according to the present invention.

The terms or words used in this specification and claims are not to be construed as being limited to conventional or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical idea of the present invention various that can be substituted for them at the time of the present application It should be understood that there may be equivalents and variations.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic configuration diagram of a heat pump system according to the present invention.

Referring to FIG. 1, the heat pump system of the present embodiment includes an electric compressor 10, a condenser 20, an expansion valve 30, an evaporator 40, and a pressure sensor 50.

The electric compressor 10 compresses and discharges the introduced refrigerant. The motor-driven compressor 10 may have various configurations and structures. The motor-driven compressor 10 of the present embodiment may be implemented as a scroll compressor or another compressor that performs a function corresponding to the scroll compressor. In addition, the motor-driven compressor 10 may be implemented as an inverter-integrated motor-driven compressor having an inverter for driving and controlling a motor provided in the motor-driven compressor.

The condenser 20 is connected to the discharge port through which the refrigerant is discharged in the electric compressor having the first heat exchanger. The expansion valve 30 is provided in the middle of the refrigerant pipe 61 connecting the condenser 20 and the evaporator 40. The evaporator 40 has a second heat exchanger and is connected to an inlet through which refrigerant is introduced into the electric compressor.

The detailed configuration and operating principle of the heat pump system having the above-described electric compressor 10, the condenser 20, the expansion valve 30 and the evaporator 40 are well known and thus detailed description thereof will be omitted.

The pressure sensor 50 detects the discharge pressure at the discharge port of the motor-driven compressor 10. The pressure sensor 50 may be provided in the refrigerant pipe 62 connected to the discharge port of the electric compressor 10. The pressure sensor may be an Automotive Pressure Transducer (APT) sensor. When the APT sensor is used, the APT sensor provided in the vehicle periodically detects the discharge pressure of the motor-driven compressor 10 periodically, and the detected discharge pressure information is transmitted to and stored in an engine control unit (hereinafter referred to as ECU). can do.

(T는 토크, kt는 모터의 토크 상수, 그리고 I는 모터의 상전류)을 통해 산출된 토크와 작동중인 모터의 속도에 의해 결정되는 파워 이하의 파워 영역에서 모터를 구동 및 제어하도록 설정된다. 이러한 전동 압축기(10)에 대하여 아래에서 좀더 상세히 설명한다.In the above-described configuration, when the discharge pressure detected through the pressure sensor is greater than a predetermined reference pressure, the equation

(T is the torque, kt is the torque constant of the motor, and I is the phase current of the motor) and is set to drive and control the motor in a power region below the power determined by the speed of the motor being operated. The motor-driven compressor 10 will be described in more detail below.

FIG. 2 is a block diagram illustrating a schematic configuration of a motor-driven compressor of the heat pump system of FIG. 1 and a connection relationship with a FATC and an ECU.

Referring to FIG. 2, the motor-driven compressor 10 according to the present embodiment includes an inverter 11 and a scroll compressor 15. The inverter 11 includes an inverter controller 12, and the scroll compressor 15 includes a motor 13 and a scroll compression unit 14.

The inverter 11 is for driving and controlling the motor of the motor-driven compressor 10. The inverter 11 includes a high voltage unit including elements for operating power and motor operation power of integrated circuits, and a low voltage unit including elements for communication for communication with an ECU 80, a full automatic temperature control (FATC), etc. of a vehicle. It can be provided. The communication refers to controller area network (CAN) communication and the like.

The inverter controller 12 receives a mode signal corresponding to the discharge pressure and the operation mode of the heat pump system from the FATC 70. The mode signal may include a heating mode and an air conditioning mode. Here, the inverter controller 12 may be implemented as an integrated circuit of the high voltage portion of the inverter 11, the FATC 70 receives and stores the discharge pressure from the ECU 80 of the electric or hybrid vehicle connected to the APT sensor Can be.

The scroll compressor 15 is a device that compresses a refrigerant (air or the like) by relatively moving two scroll-shaped parts. As the scroll compressor 15 rotates between the fixed scroll and the swing scroll, a crescent-shaped enclosed space (compression chamber) formed by both scrolls changes its volume in accordance with the relative movement of both scrolls, so that the refrigerant is sucked, compressed and discharged. Repeat the administration.

In the scroll compressor 15, the motor 13 engages with the swing scroll to rotate the swing scroll. The scroll compression unit 14 may correspond to a fixed scroll and a swing scroll coupled to the motor 13 and a housing surrounding the scroll scroll and the coolant inlet and the coolant outlet.

3 is a block diagram schematically illustrating the configuration of the inverter controller of FIG. 2.

Referring to FIG. 3, the inverter controller 12 according to the present exemplary embodiment may include a heating mode determining unit 121, a speed control unit 122, a discharge pressure receiving unit 123, a comparison unit 124, and a power control unit 125. It is provided.

The heating mode determination unit 121 determines the heating mode or the air conditioner mode based on the mode signal from the FATC. The mode signal may include a first signal of a first level corresponding to the heating mode and a second signal of a second level corresponding to the air conditioning mode and distinguished from the first level.

The speed controller 122 drives and controls the motor based on a control scheme preset for the inverter controller 12, for example, a speed feedback Wm in the air conditioner mode. In addition, when the discharge pressure of the electric compressor is equal to or less than a predetermined reference pressure, the speed controller 122 may drive and control the motor similarly to the air conditioner mode in the heating mode.

The discharge pressure receiving unit 123 receives the discharge pressure Pd of the electric compressor from the FATC in the heating mode. When the discharge pressure Pd exceeds a threshold value (specific pressure above the reference pressure, etc.), a high pressure (excessive discharge pressure) occurs in the condenser (indoor condenser, etc.) of the heat pump system, and corresponds to the high pressure through the scroll compressor of the electric compressor. Excessive torque is applied to the motor, and the excessive torque causes overcurrent in the motor, and the electric compressor is placed in an overloaded state. Therefore, the heat pump system according to the present embodiment periodically receives the discharge pressure in order to monitor the discharge pressure of the electric compressor in the heating mode in which excessive torque is likely to occur.

The discharge pressure receiving unit 123 may receive the discharge pressure from the FATC according to a preset processing procedure between the inverter controller 12 and the FATC to transmit and receive the discharge pressure information. For example, the discharge pressure receiver 123 is set to periodically read the discharge pressure information stored in a specific memory address of the FATC, or the FATC periodically transmits the discharge pressure information stored in its memory to the discharge pressure receiver 123. Can be set.

The comparator 124 compares the discharge pressure with a preset reference pressure. The reference pressure is for determining whether excessive torque by the scroll compression unit is applied to the motor, and may be appropriately selected according to the capacity of the heat pump system or the electric compressor. When excessive torque is applied to the motor, overcurrent flows through the inverter of the motor-driven compressor, thereby driving and controlling the motor may become unstable. The comparison unit 124 may be simply implemented as a logic circuit such as a flip-flop.

As a result of the comparison in the comparison unit 124, the power control unit 124, when the discharge pressure is greater than the reference pressure, the power control unit 124 is below the threshold power based on the power (critical power) determined by the calculated torque and the speed of the motor in operation. Drive and control the motor in the operating area. The power control unit 124 may constantly control the current supplied to the motor so that the speed (RPM) of the motor is lowered to a stable driving range when the torque is excessively high.

4 is a flowchart of a control method of a heat pump system according to the present invention.

4, the control method of the heat pump system according to the present embodiment, the heating mode determination step (S41), discharge pressure receiving step (S42), pressure comparison step (S43), power control step (S44) and speed A control step S45 is provided.

In more detail, each step of the heating mode determination step (S41), the inverter controller of the electric compressor of the electric vehicle or hybrid vehicle determines whether the heat pump system is the heating mode or the air conditioning mode based on the mode signal input from the outside. To judge. The heating mode may for example be set to run at an ambient temperature of 10 ° C. or higher.

In the discharge pressure receiving step S42, when the heat pump system is in the heating mode, the inverter controller receives the discharge pressure Pd of the electric compressor of the heat pump system. In the present embodiment, the discharge pressure receiving step (S42), the inverter controller is connected via a communication channel such as a full automatic temperature control (FATC) (70) and CAN communication according to a predetermined setting, discharge pressure from the FATC (60) (Pd) can be made to receive. Here, the FATC 70 may receive the discharge pressure Pd from the ECU 80 of the vehicle. In that case, the ECU 80 is preferably set to receive and store the discharge pressure periodically connected to the APT (Automotive Pressure Transducer) sensor.

In the pressure comparison step S43, the inverter controller compares the discharge pressure Pd with the preset reference pressure Pref. In this embodiment, the pressure comparison step S43 is for determining whether excessive torque occurs in the electric compressor due to the high pressure generated in the condenser of the heat pump system in the heating mode.

(T는 토크, kt는 모터의 토크 상수, 그리고 I는 모터의 상전류)을 통해 산출된 토크와 작동중인 모터의 속도에 의해 결정되는 파워 이하의 파워 영역에서 모터를 구동 및 제어한다.In the power control step (S44), the inverter controller when the discharge pressure is greater than the reference pressure, the equation

(T is the torque, kt is the torque constant of the motor, and I is the motor's phase current) and the motor is driven and controlled in a power region below the power determined by the speed of the running motor.

In the speed control step S45, when the discharge pressure is below the reference pressure, the inverter controller drives and controls the motor based on the speed detection or the speed feedback of the motor. In the present embodiment, the speed control step S45 may be performed when the heat pump system is in the air conditioner mode instead of the heating mode, as a result of the determination in the heating mode determination step S41. Further, the speed control step S45 may be performed when the discharge pressure is equal to or less than the reference pressure in the pressure comparison step S43.

According to the above embodiment, in the low speed and high load mode of the electric compressor, a current of more than the limit current flows to the inverter to prevent the electric compressor from being shut down by self-protection, and the high pressure is based on the motor phase current and the discharge pressure of the electric compressor. By rotating the motor at a constant speed in the region below the power calculated under the conditions, it is possible to improve the stability and reliability of the electric compressor and a heat pump system having such a motor compressor.

As described above, although the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the above-described embodiments and the general knowledge in the art to which the present invention pertains without departing from the spirit of the present invention. Various changes, substitutions, and modifications will be possible by those having the same, and such changes, substitutions, and modifications should be regarded as belonging to the claims of the present invention.

10: electric compressor 11: inverter
12: inverter controller 13: motor
20: condenser 30: expansion valve
40: evaporator 50: pressure sensor
61, 62: refrigerant pipe

Claims (9)

Electric compressor 10;
A condenser 20 having a first heat exchanger and connected to an outlet of the electric compressor;
An evaporator 40 connected to an inlet of said electric compressor having a second heat exchanger;
An expansion valve 30 provided in the middle of the refrigerant pipe 61 connecting the condenser and the evaporator;
A pressure sensor 50 for detecting a discharge pressure of the discharge port of the electric compressor; And
When the discharge pressure detected through the pressure sensor is greater than the predetermined reference pressure, the equation

(T is the torque, kt is the torque constant of the motor, and I is the motor's phase current) to drive and control the motor 13 in a power region below the power determined by the torque and the speed of the motor in operation. An inverter controller (12). The method according to claim 1,
The motor-driven compressor (10) comprises a scroll compressor (15) with the motor (13). The method according to claim 2,
The pressure sensor (50) comprises an APT (Automotive Pressure Transducer) sensor. The method according to claim 3,
The inverter controller 12 receives a mode signal corresponding to the discharge pressure and an operation mode of the heat pump system from a full automatic temperature control (FATC) 60, and the FATC 60 is connected to the APT sensor. A heat pump system for receiving and storing the discharge pressure from an engine control unit (ECU) of an automobile or a hybrid vehicle. The method according to claim 4,
The inverter controller 12,
A heating mode determination unit 121 for determining a heating mode based on the mode signal from the FATC 60;
A speed controller 122 for driving and controlling the motor 13 based on the speed feedback in the air conditioner mode;
A discharge pressure receiver 123 for receiving a discharge pressure of the electric compressor 10 from the FATC 60 in the heating mode;
A comparator 124 for comparing the discharge pressure with a preset reference pressure; And
And a power controller 125 for driving and controlling the motor in a power region below the power determined by the calculated torque and the speed of the motor in operation when the discharge pressure is greater than the reference pressure. . Determining whether the heat pump system is in a heating mode based on a mode signal input from the outside in an inverter controller of an electric compressor of an electric vehicle or a hybrid vehicle (S41);
If the heat pump system is in a heating mode, receiving a discharge pressure of the electric compressor of the heat pump system (S42);
Comparing the discharge pressure with a preset reference pressure (S43); And
When the discharge pressure is greater than the reference pressure, when the discharge pressure detected through the pressure sensor is greater than the predetermined reference pressure, the equation

Driving and controlling the motor in a power region below the power determined by the torque calculated through the torque (T is the torque, kt is the torque constant of the motor, and I is the phase current of the motor) and the speed of the motor in operation S44 Method of controlling a heat pump system comprising a. The method according to claim 6,
The method may further include controlling the speed of the motor (S45), and controlling the speed of the motor may be performed when the heat pump system is in an air conditioner mode (S41). How to control the heat pump system. The method according to claim 6,
Speed control of the motor (S45), the control method of the heat pump system is performed when the discharge pressure is equal to or less than the reference pressure in the step (S43) of comparing the discharge pressure and the reference pressure. The method according to claim 6,
Receiving the discharge pressure of the electric compressor (S42), the inverter controller includes receiving the mode signal and the discharge pressure from a Full Automatic Temperature Control (FATC) (60), wherein the FATC (60) The control method of the heat pump system for receiving and storing the discharge pressure from the engine control unit (Engine Control Unit, ECU, 70) connected to the APT (Automotive Pressure Transducer) sensor.

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