EP-4741739-A1 - CONTROL DEVICE, REFRIGERATION CYCLE DEVICE, CONTROL METHOD, AND PROGRAM

EP4741739A1EP 4741739 A1EP4741739 A1EP 4741739A1EP-4741739-A1

Abstract

Provided are a control device, a refrigeration cycle device, a control method, and a program, which enable improvement of suppression of a disproportionation reaction of a working medium. The control device controls a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium. The control device includes: a drive circuit to drive the compressor; a state detection circuit to detect a state of at least one of the compressor or the drive circuit; a switching device to switch between a first route connecting a discharge pipe of the compressor to the condenser and a second route connecting the discharge pipe of the compressor to a predetermined space decreasing an internal pressure of the compressor to be a predetermined pressure or less; and a control circuit to control the drive circuit and the switching device. The control circuit switches from the first route to the second route by the switching device when the state of at least one of the compressor or the drive circuit detected by the state detection circuit indicates a non-steady state of the refrigeration cycle circuit.

Inventors

TSUNOYAMA, HIRONORI
NAGAO, NOBUAKI
MURAKAMI, HIKARU
HIWATA, AKIRA
HASHIMOTO, TAKAHIKO

Assignees

Panasonic Intellectual Property Management Co., Ltd.

Dates

Publication Date: 20260513
Application Date: 20240624

Claims (20)

A control device for controlling a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium, comprising: a drive circuit configured to drive the compressor; a state detection circuit configured to detect a state of at least one of the compressor or the drive circuit; a switching device configured to switch between a first route connecting a discharge pipe of the compressor to the condenser and a second route connecting the discharge pipe of the compressor to a predetermined space decreasing an internal pressure of the compressor to be a predetermined pressure or less; and a control circuit configured to control the drive circuit and the switching device, the control circuit being configured to switch from the first route to the second route by the switching device when the state of at least one of the compressor or the drive circuit detected by the state detection circuit indicates a non-steady state of the refrigeration cycle circuit.
The control device of claim 1, wherein the predetermined space has a pressure of 0.4 MPa or less.
The control device of claim 1, wherein the predetermined pressure is 3.0 MPa or less.
The control device of claim 1, wherein: the switching device is positioned between the discharge pipe of the compressor and the condenser; the first route connects the discharge pipe of the compressor to the condenser; and the second route connects the discharge pipe of the compressor to the predetermined space.
The control device of claim 4, wherein: the refrigeration cycle circuit includes an accumulator positioned closer to a suction pipe of the compressor; and the second route connects the discharge pipe of the compressor to an internal space of the accumulator.
The control device of claim 1, wherein: the refrigeration cycle circuit includes a first heat exchanger and a second heat exchanger; the switching device is a four-way valve configured to switch a direction in which the working medium circulates through the refrigeration cycle circuit between a first direction corresponding to a cooling operation and a second direction corresponding to a heating operation; the first route corresponds to the second direction and connects the discharge pipe of the compressor to the second heat exchanger; the second route corresponds to the first direction and connects the discharge pipe of the compressor to the first heat exchanger; and the control circuit is configured to switch from the first route to the second route by the switching device and increase a degree of opening of the expansion value when the state of at least one of the compressor or the drive circuit detected by the state detection circuit indicates the non-steady state.
The control device of claim 1, wherein the control circuit is configured to interrupt or limit an operation of the drive circuit when the state of at least one of the compressor or the drive circuit detected by the state detection circuit indicates the non-steady state.
The control device of claim 7, wherein: the drive circuit includes an inverter circuit configured to output AC output power to the compressor; the state detection circuit is configured to detect the AC output power; and the non-steady state includes an abnormality relating to a leakage current detectable among connecting lines individually corresponding to three phases of the AC output power.
The control device of claim 7, wherein: the drive circuit includes a converter circuit configured to output DC output power so that a voltage of the DC output power is equal to a first voltage, based on input power from a power supply, and an inverter circuit configured to output AC output power to the compressor, based on the DC output power; the state detection circuit is configured to detect the DC output power to output a detection voltage indicative of the voltage of the DC output power; and the non-steady state includes a state where the detection voltage is lower than a second voltage equal to or lower than the first voltage.
The control device of claim 9, wherein the second voltage is between 0.3 and 0.8 times the first voltage, inclusive.
The control device of claim 1, wherein the control circuit is configured to switch from the first route to the second route by the switching device and then interrupt an operation of the drive circuit, and restart the operation of the drive circuit when determining the non-steady state is no longer continuing based on at least one of a time-dependent change in a pressure, a temperature, or a product amount inside the refrigeration cycle circuit.
A refrigeration cycle device comprising: the control device of claim 1; and the refrigeration cycle circuit.
The refrigeration cycle device of claim 12, wherein the working medium contains ethylene-based fluoroolefin.
The refrigeration cycle device of claim 13, wherein the ethylene-based fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene.
The refrigeration cycle device of claim 12, wherein the working medium further contains difluoromethane.
The refrigeration cycle device of claim 12, wherein the working medium further contains a saturated hydrocarbon.
The refrigeration cycle device of claim 13, wherein the working medium contains a haloalkane with 1 or 2 carbon atoms as a disproportionation inhibitor for suppressing a disproportionation reaction of the ethylene-based fluoroolefin.
The refrigeration cycle device of claim 16, wherein the saturated hydrocarbon contains n-propane.
A control method performed by a control device for controlling a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium, the control device including a drive circuit configured to drive the compressor, and a control circuit configured to control the drive circuit, the control method comprising connecting a discharge pipe of the compressor to a predetermined space to decrease an internal pressure of the compressor to a predetermined pressure or less, when a state of at least one of the compressor or the drive circuit indicates a non-steady state of the refrigeration cycle circuit.
A program executed by a computer system included in a control device for controlling a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium, the control device including a drive circuit configured to drive the compressor, and a control circuit configured to control the drive circuit, the program allowing the computer system to connect a discharge pipe of the compressor to a predetermined space to decrease an internal pressure of the compressor to a predetermined pressure or less, when a state of at least one of the compressor or the drive circuit indicates a non-steady state of the refrigeration cycle circuit.

Description

TECHNICAL FIELD The present disclosure relates to control devices, refrigeration cycle devices, control methods, and programs. BACKGROUND ART Conventionally, R410A has been widely used as a working medium (heat medium, refrigerant) for refrigeration cycle devices. However, the global warming potential (GWP) of R410A is as high as 2090. Therefore, from the viewpoint of preventing global warming, research and development of working media with smaller GWPs has been conducted. Patent Document 1 discloses 1,1,2-trifluoroethylene (HFO1123) as a working medium with a smaller GWP than R410A. Patent Document 2 discloses 1,2-difluoroethylene (HFO1132) as a working medium with a smaller GWP than R410A. HFO1123 and HFO1132 have a smaller GWP than R410A, but are therefore less stable than R410A. For example, the generation of radicals may cause a disproportionation reaction of HFO1123 or HFO1132, resulting in the conversion of HFO1123 and HFO1132 to other compounds. Patent Document 3 discloses a refrigeration cycle device which aims to improve the reliability of a refrigeration cycle device that uses a working medium containing HFO1123. The refrigeration cycle device disclosed in Patent Document 3 constitutes a refrigeration cycle by annularly connecting a compressor equipped with an electric motor, a condenser, an expansion means, and an evaporator, and by sealing a working medium containing an ethylene-based fluorohydrocarbon having a double bond in the refrigeration cycle. The device further includes a protective device that interrupts the power supply to the compressor when a current value input to the compressor exceeds a predetermined current value, which is set to be at least three times the maximum current value during normal operation other than at start-up, or at least twice the current value at start-up. PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: WO 2012/157764 A1Patent Document 2: WO 2012/157765 A1Patent Document 3: JP 2019-152380 A SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION Patent Document 3 states that "when the current value input to the compressor becomes equal to or greater than a predetermined value, the power supply to the electric motor is stopped, thereby suppressing layer short-circuiting caused by overcurrent and effectively suppressing a disproportionation reaction." The discharge energy that affects the propagation of the disproportionation reaction greatly depends on the internal pressure of the compressor, and when the internal pressure of the compressor is high, the disproportionation reaction may not be sufficiently suppressed. The present disclosure provides a control device, a refrigeration cycle device, a control method, and a program, which enable improvement of suppression of a disproportionation reaction of a working medium. SOLUTIONS TO THE PROBLEMS A control device according to one aspect of the present disclosure is configured to control a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium. The control device includes: a drive circuit configured to drive the compressor; a state detection circuit configured to detect a state of at least one of the compressor or the drive circuit; a switching device configured to switch between a first route connecting a discharge pipe of the compressor to the condenser and a second route connecting the discharge pipe of the compressor to a predetermined space decreasing an internal pressure of the compressor to be a predetermined pressure or less; and a control circuit configured to control the drive circuit and the switching device. The control circuit is configured to switch from the first route to the second route by the switching device when the state of at least one of the compressor or the drive circuit detected by the state detection circuit indicates a non-steady state of the refrigeration cycle circuit. A refrigeration cycle device according to one aspect of the present disclosure includes: the control device; and the refrigeration cycle circuit. A control method according to one aspect of the present disclosure is performed by a control device for controlling a refrigeration cycle circuit which includes a compressor, a condenser, an expansion valve, and an evaporator and allows circulation of a working medium. The control device includes a drive circuit configured to drive the compressor, and a control circuit configured to control the drive circuit. The control method includes connecting a discharge pipe of the compressor to a predetermined space to decrease an internal pressure of the compressor to a predetermined pressure or less, when a state of at least one of the compressor or the drive circuit indicates a non-steady state of the refrigeration cycle circuit. A program according to one aspect of the present disclosure is executed by a computer system included in a control device for controlling a refrige