Inverter device, refrigeration cycle device, and inverter control method

Abstract

Provided is an inverter device that suppresses a decrease in temperature of an electrolytic capacitor when there is not a drive command issued for the inverter device.　This cold inverter device has: an electrolytic capacitor that smooths an input voltage and generates a DC voltage; an inverter unit that generates an AC voltage from the DC voltage and drives a motor; and a control unit that controls heating of the electrolytic capacitor. The control unit heats the electrolytic capacitor if the temperature of the electrolytic capacitor is less than a predetermined first threshold value when no voltage is applied to the motor, and the control unit heats the electrolytic capacitor if the voltage is not applied to the motor after determining whether the temperature of the electrolytic capacitor is less than the first threshold value, and the temperature of the electrolytic capacitor is less than a second threshold value that is a value smaller than the predetermined first threshold value.

Description

Inverter device, refrigeration cycle device, and inverter control method

[0001] The present disclosure relates to an inverter device, a refrigeration cycle device, and an inverter control method.

[0002] Generally, inverter devices that control the voltage of an AC power supply are known. The inverter device includes a converter unit that rectifies the AC voltage and converts it into a pulsating voltage, an electrolytic capacitor that smoothes the pulsating voltage, and an inverter unit that converts the smoothed DC voltage back into an AC voltage.

[0003] The performance of electrolytic capacitors deteriorates in low-temperature environments, so when an inverter device is operated in a low-temperature environment, the electrolytic capacitors must be warmed up before operation.

[0004] In the inverter device described in Patent Document 1, if the temperature of the electrolytic capacitor in the inverter device is lower than the target temperature when a command to drive the electric motor is issued, the temperature of the electrolytic capacitor is raised to the target temperature by passing current through the electric motor before starting normal operation of the electric motor.

[0005] JP 2012-222925 A

[0006] However, the inverter device described in Patent Document 1 has a problem in that the temperature of the electrolytic capacitor drops when the motor is in a low-temperature environment and no drive command is issued for a long period of time.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to prevent the temperature of the electrolytic capacitor from decreasing when no drive command for the inverter device is issued.

[0008] The inverter device of the present disclosure includes an electrolytic capacitor that smooths an input voltage to generate a DC voltage, an inverter unit that generates an AC voltage from the DC voltage to drive a motor, and a control unit that controls heating of the electrolytic capacitor, wherein the control unit heats the electrolytic capacitor if the temperature of the electrolytic capacitor when no voltage is applied to the motor is less than a predetermined first threshold, and heats the electrolytic capacitor if, after determining whether the temperature of the electrolytic capacitor is less than the first threshold, no voltage is applied to the motor and the temperature of the electrolytic capacitor is less than a second threshold that is a value smaller than the predetermined first threshold.

[0009] The refrigeration cycle device of the present disclosure includes a compressor that compresses a refrigerant, an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant, a pressure reducing device that reduces the pressure of the refrigerant, an indoor heat exchanger that exchanges heat between indoor air and the refrigerant, and refrigerant piping that connects the compressor, the outdoor heat exchanger, the pressure reducing device, and the indoor heat exchanger to form a refrigerant circuit. The inverter device that drives the motor of the compressor includes an electrolytic capacitor that smooths an input voltage to generate a DC voltage, an inverter unit that generates an AC voltage from the DC voltage to drive the motor, and a control unit that controls heating of the electrolytic capacitor. The control unit heats the electrolytic capacitor when the temperature of the electrolytic capacitor is less than a predetermined first threshold value when no voltage is applied to the motor, and heats the electrolytic capacitor when no voltage is applied to the motor after determining whether the temperature of the electrolytic capacitor is less than the first threshold value and when the temperature of the electrolytic capacitor is less than a second threshold value that is smaller than the predetermined first threshold value.

[0010] The inverter control method of the present disclosure also includes an inverter device having an electrolytic capacitor that smooths an input voltage to generate a DC voltage, an inverter unit that generates an AC voltage from the DC voltage to drive a motor, and a control unit that controls heating of the electrolytic capacitor, the inverter control method comprising: a first step in which the control unit heats the electrolytic capacitor when the temperature of the electrolytic capacitor when no voltage is applied to the motor is less than a predetermined first threshold; and a second step in which the control unit heats the electrolytic capacitor after the first step when the temperature of the electrolytic capacitor is less than a second threshold that is smaller than the predetermined first threshold.

[0011] The inverter device, the refrigeration cycle device, and the inverter control method of the present disclosure can suppress a decrease in the temperature of the electrolytic capacitor when no drive command for the inverter device is issued.

[0012] Fig. 1 is a refrigerant circuit diagram showing an overview of a refrigeration cycle device according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of a compressor of a refrigeration cycle device according to an embodiment of the present disclosure. Fig. 3 is a circuit diagram showing a configuration of an inverter device of a refrigeration cycle device according to an embodiment of the present disclosure. Fig. 4 is a block diagram showing a functional configuration of a control unit of an inverter device according to an embodiment of the present disclosure. Fig. 5 is a block diagram showing a hardware configuration of a control unit of an inverter device according to an embodiment of the present disclosure. Fig. 6 is a flowchart showing processing contents of a control unit of an inverter device according to an embodiment of the present disclosure. Fig. 7 is a flowchart showing processing contents of a heating operation mode performed by a control unit of an inverter device according to an embodiment of the present disclosure.

[0013] An inverter device, a refrigeration cycle device, and an inverter control method according to embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following embodiments, and modifications or omissions may be made without departing from the spirit of the present disclosure. Furthermore, common elements in each drawing will be assigned the same reference numerals, and redundant explanations will be omitted.

[0014] 1 is a refrigerant circuit diagram showing an overview of a refrigeration cycle apparatus 100 according to an embodiment of the present disclosure. The configuration of the refrigeration cycle apparatus 100 will be described with reference to FIG. 1.

[0015] As shown in Fig. 1, the refrigeration cycle apparatus 100 includes an indoor unit 110 and an outdoor unit 120. Furthermore, refrigerant piping 130 connects the components of the refrigeration cycle apparatus 100 so that the refrigerant circulates between them. In Fig. 1, the flow of the refrigerant during heating operation in the refrigeration cycle apparatus 100 is indicated by dashed arrows, and the flow of the refrigerant during cooling operation is indicated by solid arrows.

[0016] The indoor unit 110 includes an indoor heat exchanger 111 and an indoor blower 112. The indoor heat exchanger 111 exchanges heat between the indoor air of the building and the outdoor air. The indoor blower 112 blows indoor air to the indoor heat exchanger 111.

[0017] The outdoor unit 120 includes a compressor 121, an inverter device 122, a pressure reducing device 123, an outdoor heat exchanger 124, an outdoor blower 125, and a four-way valve 126. The outdoor unit 120 is formed such that each component device is connected to the other component device by refrigerant piping 130.

[0018] The compressor 121 compresses and discharges the refrigerant. More specifically, the compressor 121 is a scroll compressor. The inverter device 122 is connected to the AC power supply 50 and controls the power applied to the compressor 121. The AC power supply 50 is a three-phase AC power supply. Detailed configurations of the compressor 121 and the inverter device 122 will be described later.

[0019] The pressure reducing device 123 is a device that reduces the pressure of the refrigerant, and more specifically, is an expansion valve. The outdoor heat exchanger 124 exchanges heat between the refrigerant and air outside the building. The outdoor air blower 125 blows outdoor air to the outdoor heat exchanger 124.

[0020] The four-way valve 126 switches between a refrigerant circuit for heating operation and a refrigerant circuit for cooling operation. The four-way valve 126 is, for example, a differential pressure driven four-way valve.

[0021] Using FIG. 1, the flow of refrigerant when the refrigeration cycle apparatus 100 is operating in cooling mode will be described. High-pressure gas refrigerant discharged from the compressor 121 flows into the outdoor heat exchanger 124. The high-pressure gas refrigerant that flows into the outdoor heat exchanger is condensed and becomes liquid refrigerant. The liquid refrigerant that flows out of the outdoor heat exchanger 124 flows into the pressure reducing device 123. The refrigerant that flows into the pressure reducing device 123 is decompressed and expands, becoming low-pressure two-phase gas-liquid refrigerant. The low-pressure two-phase gas-liquid refrigerant that flows out of the pressure reducing device 123 flows into the indoor unit 110 and then into the indoor heat exchanger 111. The low-pressure two-phase gas-liquid refrigerant that flows into the indoor heat exchanger 111 evaporates and becomes low-pressure gas refrigerant. The low-pressure gas refrigerant that flows out of the indoor heat exchanger 111 flows into the compressor 121. By circulating the refrigerant in this manner, the indoor air is cooled by the low-pressure refrigerant in a gas-liquid two-phase state in the indoor heat exchanger 111 .

[0022] Next, the flow of refrigerant when the refrigeration cycle apparatus 100 performs heating operation will be described using FIG. 1 . High-pressure gas refrigerant discharged from the compressor 121 flows into the indoor heat exchanger 111. The high-pressure gas refrigerant that flows into the indoor heat exchanger 111 is condensed into liquid refrigerant. The liquid refrigerant that flows out of the indoor heat exchanger 111 flows into the pressure reducing device 123. The liquid refrigerant that flows into the pressure reducing device 123 is decompressed and expands, becoming low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant that flows out of the pressure reducing device 123 flows into the outdoor unit 120 and then into the outdoor heat exchanger 124. The low-pressure two-phase gas-liquid refrigerant that flows into the outdoor heat exchanger 124 evaporates into low-pressure gas refrigerant. The low-pressure gas refrigerant that flows out of the outdoor heat exchanger 124 flows into the compressor 121. By circulating the refrigerant in this manner, the indoor air is heated by the high-temperature, high-pressure gas refrigerant in the indoor heat exchanger 111 .

[0023] Fig. 2 is a schematic cross-sectional view of the compressor 121 of the refrigeration cycle apparatus 100 according to the embodiment of the present disclosure. Fig. 3 is a circuit diagram showing the configuration of the inverter device 122 of the refrigeration cycle apparatus 100 according to the embodiment of the present disclosure. The detailed configurations of the compressor 121 and the inverter device 122 of the refrigeration cycle apparatus 100 will be described using Fig. 2 and Fig. 3. In Fig. 2, the flow of refrigerant in the compressor 121 is indicated by arrows.

[0024] As shown in FIG. 2 , the compressor 121 has a suction port 20 , a compressor motor 21 , a drive shaft 22 , a compression chamber 23 , and a discharge port 24 .

[0025] The intake port 20 draws refrigerant into the compressor 121. The compressor motor 21 drives the compression chamber 23. Specifically, the compressor motor 21 rotates a drive shaft 22. The compressor motor 21 is provided below the compression chamber 23. The power applied to the compressor motor 21 is controlled by an inverter device 122. As shown in FIG. 3 , the compressor motor 21 is a three-phase motor. The compressor motor 21 includes a stator 21a and a rotor 21b.

[0026] The stator 21a is a ring-shaped stator fixed to the inner surface of the compressor 121 by, for example, shrink fitting. The stator 21a is configured, for example, by windings wound around an iron core made of multiple laminated electromagnetic steel sheets with an insulating layer interposed between them. The rotor 21b is disposed in the internal space of the stator 21a and is a cylindrical rotor having a through-hole that passes through it in the vertical direction in the center. The rotor 21b is configured, for example, by incorporating a permanent magnet inside an iron core made of multiple laminated electromagnetic steel sheets.

[0027] The drive shaft 22 transmits the rotational force generated by the compressor motor 21 to the compression chamber 23. The drive shaft 22 is, for example, a rod-shaped member made of metal. The drive shaft 22 is disposed inside the compressor 121 so that its axial direction is in the up-down direction.

[0028] The compression chamber 23 compresses the refrigerant. The discharge port 24 discharges the refrigerant compressed in the compression chamber 23 to the outside of the compressor 121.

[0029] 3 , the inverter device 122 is connected to the AC power supply 50 and the compressor motor 21, and controls the power applied to the compressor motor 21. The inverter device 122 has a circuit including the converter unit 10, the film capacitor 11, and the inverter unit 12, a temperature detection unit 30, a voltage detection unit 31, and a control unit 32.

[0030] The converter unit 10 converts an AC voltage obtained from an AC power supply 50 into a DC voltage. The converter unit 10 includes a rectifier unit 2, a reactor 3, a diode 4, an electrolytic capacitor 5, and a resistor 6.

[0031] The rectifier 2 converts the AC voltage obtained from the AC power supply 50 into a pulsating voltage by rectifying the AC voltage. More specifically, the rectifier 2 is a diode bridge circuit.

[0032] The reactor 3 removes noise contained in the pulsating voltage converted by the rectifier 2. The diode 4 prevents a reverse voltage from being generated in the pulsating voltage converted by the rectifier 2, thereby protecting the inverter device 122.

[0033] The electrolytic capacitor 5 smoothes the pulsating voltage converted by the rectifier 2 and converts it into a DC voltage. The electrolytic capacitor 5 is connected in parallel with the rectifier 2 to the circuit of the inverter device 122. The electrolytic capacitor 5 charges when the pulsating voltage converted by the rectifier 2 exceeds a certain value, and discharges when it falls below the certain value. In this way, the electrolytic capacitor 5 smoothes the pulsating voltage output from the rectifier 2 by repeatedly charging and discharging. Specifically, the electrolytic capacitor 5 is an aluminum electrolytic capacitor.

[0034] The resistor 6 controls the discharge of the electrolytic capacitor 5 and suppresses sudden current or voltage fluctuations. The resistor 6 is connected in parallel with the electrolytic capacitor 5 to the circuit of the inverter device 122.

[0035] The film capacitor 11 reduces the ripple voltage contained in the DC voltage. The film capacitor 11 is connected in parallel with the rectifier 2 to the circuit of the inverter device 122.

[0036] The inverter unit 12 converts the DC voltage into an AC voltage based on a signal determined by the control unit 32. The detailed configuration of the control unit 32 will be described later. The inverter unit 12 also has two operation modes: a normal operation mode and a heating operation mode. In the normal operation mode, the inverter unit 12 drives the compressor motor 21. In the heating operation mode, the inverter unit 12 heats the electrolytic capacitor 5 without driving the compressor motor 21. More specifically, the inverter unit 12 heats the electrolytic capacitor 5 by Joule heat generated by applying a voltage to the compressor motor 21 that does not generate a rotating magnetic field. The heating operation mode is performed until the temperature of the electrolytic capacitor 5 reaches or exceeds a predetermined first threshold.

[0037] The inverter unit 12 implements the heating operation mode if the temperature of the electrolytic capacitor 5 is below a predetermined first threshold value when a predetermined first detection time has elapsed since the compressor motor 21 stopped driving, that is, since it detected a state in which no voltage is applied to the compressor motor 21. Furthermore, the inverter unit 12 implements the heating operation mode if the temperature of the electrolytic capacitor 5 is below a predetermined second threshold value that is smaller than the first threshold value when a predetermined second detection time has elapsed since it detected the temperature of the electrolytic capacitor 5, the second detection time being a predetermined value and shorter than the first detection time.

[0038] In other words, the heating operation mode is implemented at predetermined intervals (first detection time, second detection time) when the temperature of the electrolytic capacitor 5 is decreasing when a drive command for the compressor motor 21 is not issued. If a drive command for the compressor motor 21 is not issued for a long period of time and the ambient temperature is low, the electrolyte in the electrolytic capacitor 5 may freeze. If the electrolyte in the electrolytic capacitor 5 freezes, irreversible problems such as cracking or leakage may occur. Therefore, it is necessary to prevent the temperature of the electrolytic capacitor 5 from decreasing when a drive command for the inverter device 122 is not issued. The inverter device 122 of the embodiment achieves the effect of preventing the temperature of the electrolytic capacitor 5 from decreasing when a drive command for the inverter device 122 is not issued by implementing the heating operation mode and warming the electrolytic capacitor 5.

[0039] In other words, when no drive command for the compressor motor 21 is issued, the voltage applied to the compressor motor 21 is 0 or a voltage that does not generate a rotating magnetic field.

[0040] Furthermore, by configuring the inverter device 122 to determine whether the temperature of the electrolytic capacitor 5 is below a second threshold value, which is smaller than the first threshold value, when a second detection time has elapsed since the temperature of the electrolytic capacitor 5 was detected, the inverter device 122 can prevent the temperature of the electrolytic capacitor 5 from decreasing when the temperature of the electrolytic capacitor 5 decreases due to the surrounding environment.

[0041] In the embodiment, the second detection time is shorter than the first detection time. With this configuration, the inverter device 122 of the embodiment can efficiently suppress a decrease in the temperature of the electrolytic capacitor 5 due to the ambient environment of the electrolytic capacitor 5.

[0042] Next, a method for heating the electrolytic capacitor 5 will be described. As shown in FIG. 2 , the uncompressed refrigerant drawn into the compressor 121 through the suction port 20 passes near the compressor motor 21. Therefore, when the inverter unit 12 operates in a heating operation mode and the compressor motor 21 generates Joule heat, the uncompressed refrigerant in the compressor 121 is heated. In this manner, by heating the uncompressed refrigerant in the compressor 121, the electrolytic capacitors installed around the compressor 121 can be heated. This configuration also has the effect of preventing the uncompressed refrigerant from becoming sluggish due to a low-temperature environment around the compressor 121.

[0043] The inverter unit 12 is a circuit configured with switching elements, such as field-effect transistors (FETs). The inverter unit 12 generates a three-phase AC voltage by switching the switching elements on and off. The inverter unit 12 also converts a DC voltage into an AC voltage using PWM (Pulse Width Modulation) control. PWM control controls output by changing the pulse width, which is the time interval between the half-value point of the peak power from the rising edge of a pulse and the half-value point of the falling edge.

[0044] The temperature detection unit 30 detects the temperature of the electrolytic capacitor 5. Hereinafter, the temperature of the electrolytic capacitor 5 detected by the temperature detection unit 30 will be referred to as the detected temperature. The temperature detection unit 30 is a temperature sensor, and more specifically, a thermocouple or a resistance sensor. The temperature detection unit 30 detects the detected temperature at regular time intervals. In addition, the temperature detection unit 30 transmits a signal indicating the detected temperature to the control unit 32.

[0045] The voltage detection unit 31 detects the value of the voltage applied to the compressor motor 21. Specifically, the voltage detection unit 31 is a voltmeter. The voltage detection unit 31 also transmits a signal indicating the value of the voltage applied to the compressor motor 21 to the control unit 32.

[0046] The control unit 32 controls the inverter unit 12. More specifically, the control unit 32 determines a pulse signal for the inverter unit 12. For example, the control unit 32 determines the pulse signal using a triangular wave comparison method. The control unit 32 causes the inverter unit 12 to operate in a normal operation mode or a heating operation mode. In other words, the control unit 32 controls heating of the electrolytic capacitor 5.

[0047] Fig. 4 is a block diagram showing the functional configuration of the control unit 32 of the inverter device 122 according to an embodiment of the present disclosure. Fig. 5 is a block diagram showing the hardware configuration of the control unit 32 of the inverter device 122 according to an embodiment of the present disclosure. The detailed configuration of the control unit 32 of the inverter device 122 will be described using Figs. 4 and 5 .

[0048] As shown in FIG. 4, the functional configuration of the control unit 32 includes a transmitting / receiving unit 310 , a temperature determining unit 311 , a drive determining unit 312 , a signal determining unit 313 , and a storage unit 314 .

[0049] The transmitting / receiving unit 310 transmits a signal from the control unit 32 or receives a signal to the control unit 32. The transmitting / receiving unit 310 receives a signal indicating a detected temperature from the temperature detection unit 30. The transmitting / receiving unit 310 also receives a signal indicating a voltage value applied to the compressor motor 21 from the voltage detection unit 31. The transmitting / receiving unit 310 also transmits a pulse signal determined by the signal determination unit 313 to the inverter unit 12.

[0050] The temperature determination unit 311 determines whether the temperature detected by the temperature detection unit 30 is less than a first threshold value or less than a second threshold value.

[0051] The drive determination unit 312 determines whether the compressor motor 21 is stopped. More specifically, the drive determination unit 312 determines whether the compressor motor 21 is driven based on the voltage value applied to the compressor motor 21. If the voltage value applied to the compressor motor 21 is 0, that is, if no voltage is being applied to the compressor motor 21, the drive determination unit 312 determines that the compressor motor is stopped.

[0052] The signal determination unit 313 determines a pulse signal to be sent to the inverter unit 12. More specifically, when the temperature detected by the temperature detection unit 30 while the compressor motor 21 is stopped is less than a first threshold value, the signal determination unit 313 determines a pulse signal to cause the compressor motor 21 to operate in the heating operation mode. Furthermore, when the detected temperature is less than the second threshold value when a second detection time has elapsed since the temperature detection unit 30 detected the temperature, the signal determination unit 313 determines a pulse signal to cause the compressor motor 21 to operate in the heating operation mode. Furthermore, when a drive command is issued to the compressor motor 21, the signal determination unit 313 determines a pulse signal to cause the compressor motor 21 to operate in the normal operation mode.

[0053] The storage unit 314 stores information related to the control of the inverter unit 12. Specifically, the storage unit 314 stores a first detection time, a second detection time, a first threshold value, and a second threshold value.

[0054] As shown in FIG. 5, the hardware configuration of the control unit 32 includes a processor 320 , a memory 321 , a storage 322 , and a hardware interface 323 .

[0055] The processor 320 executes a program stored in the memory 321. Specifically, when the drive determination result of the compressor motor 21 and the detected temperature satisfy the conditions, the processor 320 causes the compressor motor 21 to execute the heating operation mode. The processor 320 is, for example, a CPU (Central Processing Unit).

[0056] The memory 321 stores programs executed by the processor 320. The memory 321 is also used as a work area for the processor 320. The memory 321 is, for example, a volatile memory such as a random access memory (RAM), a non-volatile memory such as a read-only memory (ROM), or both a volatile memory and a non-volatile memory. The temperature determination unit 311, the drive determination unit 312, and the signal determination unit 313 are realized by the processor 320 and the memory 321.

[0057] The storage 322 stores the first detection time, the second detection time, the first threshold value, and the second threshold value. The storage unit 314 is realized by storing information in the storage 322.

[0058] The hardware interface 323 wirelessly or wiredly transmits and receives signals to and from the inverter unit 12 and the temperature detection unit 30. The transmitting / receiving unit 310 is realized by the hardware interface 323.

[0059] FIG. 6 is a flowchart showing the processing performed by the control unit 32 of the inverter device 122 according to an embodiment of the present disclosure. FIG. 7 is a flowchart showing the processing performed in the heating operation mode by the control unit 32 of the inverter device 122 according to an embodiment of the present disclosure. FIG. 7 shows the processing performed in step S105 in FIG. 6 in more detail. The processing performed by the control unit 32 will be described with reference to FIGS. 6 and 7. The control unit 32 starts the processing shown in FIG. 6 when the compressor motor 21 stops driving. That is, the control unit 32 performs the processing shown in FIG. 6 when the compressor motor 21 is powered on and the voltage value applied to the compressor motor 21 is zero, and ends the processing when the compressor motor 21 is not powered on.

[0060] Step S102 is performed after the first detection time stored in the memory unit 314 has elapsed since the control unit 32 started processing (step S101). In step S102, the drive determination unit 312 of the control unit 32 determines whether the compressor motor 21 has stopped driving. More specifically, the drive determination unit 312 determines whether the voltage value applied to the compressor motor 21 is 0. In step S102, the drive determination unit 312 determines whether the condition is satisfied, and the processing ends.

[0061] Step S103 is performed when it is determined in step S102 that the compressor motor 21 is stopped (Yes in step S102). In step S103, the transmitter / receiver 310 of the control unit 32 receives the detected temperature detected by the temperature detector 30. When the transmitter / receiver 310 receives the detected temperature, the process in step S103 ends.

[0062] Step S104 is performed after step S103. In step S104, the temperature determination unit 311 of the control unit 32 determines whether the detected temperature received in step S103 is less than the first threshold value stored in the storage unit 314. In step S104, the temperature determination unit 311 determines whether the condition is satisfied, and the process ends.

[0063] Step S105 is performed when it is determined in step S104 that the detected temperature is less than the first threshold value (Yes in step S104). In step S105, the control unit 32 causes the inverter unit 12 to execute the heating operation mode. More specifically, the process of step S105 includes the processes of steps S111 to S114, as shown in FIG. 6. The processes of steps S111 to S114 will be described below.

[0064] Step S111 is performed after step S104. In step S111, the signal determination unit 313 of the control unit 32 determines a pulse signal that causes the inverter unit 12 to execute the heating operation mode. When the signal determination unit 313 determines the pulse signal, the process of step S111 ends.

[0065] Step S112 is performed after step S111. In step S112, the transmitter / receiver 310 of the control unit 32 transmits the pulse signal determined in step S111 to the inverter unit 12. When the transmitter / receiver 310 transmits the pulse signal, the process of step S112 ends.

[0066] Step S113 is performed after step S112. In step S113, the transmitter / receiver 310 of the control unit 32 receives the detected temperature detected by the temperature detection unit 30. When the transmitter / receiver 310 receives the detected temperature, the process of step S113 ends.

[0067] Step S114 is performed after step S113. In step S114, the temperature determination unit 311 of the control unit 32 determines whether the detected temperature received in step S113 is equal to or greater than the first threshold value stored in the storage unit 314. In step S114, the temperature determination unit 311 determines whether the condition is satisfied, and then the process ends.

[0068] If it is determined in step S114 that the detected temperature is equal to or higher than the first threshold value (Yes in step S114), the control unit 32 ends the heating operation mode, that is, the process of step S105 ends.

[0069] If it is determined in step S114 that the detected temperature is not equal to or greater than the first threshold, i.e., is less than the first threshold (No in step S114), the signal determination unit 313 of the control unit 32 performs the process of step S111. That is, the control unit 32 of the inverter device 122 is configured to implement the heating operation mode until the detected temperature becomes equal to or greater than the first threshold. With this configuration, the inverter device 122 can effectively control the temperature of the electrolytic capacitor 5 with high accuracy.

[0070] Step S107 is performed after a second detection time, which is a value stored in the memory unit 314 and shorter than the first detection time, has elapsed since step S105 (step S106), or after the second detection time has elapsed since step S102 when it is determined that the compressor motor 21 has not stopped (step S102, No). In step S107, the drive determination unit 312 of the control unit 32 determines whether the compressor motor 21 has stopped. The drive determination method of the drive determination unit 312 is the same as that of step S102. In step S107, the drive determination unit 312 determines whether the condition is satisfied, and the process ends.

[0071] Step S108 is performed when it is determined in step S107 that the compressor motor 21 is stopped (step S107, Yes). In step S108, the transmitter / receiver 310 of the control unit 32 receives the detected temperature detected by the temperature detector 30. When the transmitter / receiver 310 receives the detected temperature, the process in step S108 ends.

[0072] If it is determined in step S107 that the compressor motor 21 has not stopped (No in step S107), the control unit 32 performs step S101. If the compressor motor 21 has not stopped, that is, if the compressor motor 21 is still running, the temperature around the compressor motor 21 is unlikely to decrease after a certain period of time, so the detection interval is set to the first detection time, which is longer than the second detection time. This configuration allows the inverter device 122 according to the embodiment to achieve the effect of reducing the capacity of the memory 321.

[0073] Step S109 is performed after step S108. In step S109, the temperature determination unit 311 of the control unit 32 determines whether the detected temperature received in step S108 is less than a second threshold value that is a value stored in the storage unit 314 and is smaller than the first threshold value. In step S104, the temperature determination unit 311 determines whether the condition is satisfied, and the process ends.

[0074] If it is determined in step S109 that the detected temperature is less than the second threshold value (Yes in step S109), the control unit 32 performs step S105. If it is determined in step S109 that the detected temperature is not less than the second threshold value (No in step S109), the control unit 32 performs step S101. In other words, if the detected temperature is equal to or greater than the second threshold value, the temperature around the compressor motor 21 is unlikely to decrease after a certain period of time, so the detection interval is set to the first detection time, which is longer than the second detection time. This configuration allows the inverter device 122 according to the embodiment to achieve the effect of reducing the capacity of the memory 321.

[0075] As described above, the inverter device 122 according to the embodiment includes the electrolytic capacitor 5 that smooths the input voltage to generate a DC voltage, the inverter unit 12 that generates an AC voltage from the DC voltage to drive the motor (corresponding to the compressor motor 21), and the control unit 32 that controls heating of the electrolytic capacitor 5. The control unit 32 heats the electrolytic capacitor 5 (performs a heating operation mode) when the temperature of the electrolytic capacitor 5 is below a predetermined first threshold when no voltage is applied to the motor, and heats the electrolytic capacitor 5 when no voltage is applied to the motor after determining whether the temperature of the electrolytic capacitor 5 is below the first threshold and the temperature of the electrolytic capacitor 5 is below a second threshold that is smaller than the first threshold. With this configuration, the inverter device 122 according to the embodiment can prevent the temperature of the electrolytic capacitor 5 from decreasing when a drive command for the inverter device 122 is not issued.

[0076] The refrigeration cycle device 100 according to the embodiment includes a compressor 121 that compresses a refrigerant, an outdoor heat exchanger 124 that exchanges heat between outdoor air and the refrigerant, a pressure reducing device 123 that reduces the pressure of the refrigerant, an indoor heat exchanger 111 that exchanges heat between indoor air and the refrigerant, and refrigerant piping 130 that connects the compressor 121, the outdoor heat exchanger 124, the pressure reducing device 123, and the indoor heat exchanger 111 to form a refrigerant circuit. The inverter device 122 that drives the motor of the compressor 121 (corresponding to the compressor motor 21) includes an electrolytic capacitor that smooths an input voltage and generates a DC voltage. The refrigeration cycle apparatus 100 according to the embodiment has a motor 5, an inverter unit 12 that generates an AC voltage from a DC voltage to drive the motor, and a control unit 32 that controls heating of the electrolytic capacitor 5, wherein the control unit 32 heats the electrolytic capacitor 5 when the temperature of the electrolytic capacitor 5 is less than a predetermined first threshold when no voltage is applied to the motor, and heats the electrolytic capacitor 5 when no voltage is applied to the motor after determining whether the temperature of the electrolytic capacitor 5 is less than the first threshold and the temperature of the electrolytic capacitor 5 is less than a second threshold that is smaller than the predetermined first threshold. With this configuration, the refrigeration cycle apparatus 100 according to the embodiment can prevent the temperature of the electrolytic capacitor 5 from decreasing when a drive command for the inverter unit 122 is not issued.

[0077] Furthermore, an inverter control method according to an embodiment includes an inverter device 122 having an electrolytic capacitor 5 that smooths an input voltage to generate a DC voltage, an inverter unit 12 that generates an AC voltage from the DC voltage to drive a motor (corresponding to compressor motor 21), and a control unit 32 that controls heating of electrolytic capacitor 5. The inverter control method includes the following steps: a first step in which, when the temperature of electrolytic capacitor 5 when no voltage is applied to the motor is below a predetermined first threshold, the control unit 32 heats electrolytic capacitor 5; and a second step in which, after the first step, the control unit 32 heats electrolytic capacitor 5 when the temperature of electrolytic capacitor 5 is below a second threshold that is smaller than the predetermined first threshold. With this configuration, the inverter control method according to an embodiment can prevent the temperature of electrolytic capacitor 5 from decreasing when a drive command for inverter device 122 is not issued.

[0078] Moreover, the inverter device 122 according to the embodiment further includes, as an additional component, a temperature detection unit 30 that detects the temperature of the electrolytic capacitor 5. With this additional component, the inverter device 122 according to the embodiment has the effect of being able to quickly obtain the temperature of the electrolytic capacitor 5.

[0079] Furthermore, the inverter device 122 according to the embodiment has an additional configuration in which heating of the electrolytic capacitor 5 is stopped when the temperature of the electrolytic capacitor 5 reaches or exceeds a first threshold value. With this additional configuration, the inverter device 122 according to the embodiment has the effect of being able to accurately control the temperature of the electrolytic capacitor 5.

[0080] Furthermore, the inverter device 122 according to the embodiment has an additional configuration in which it is heated by heat generated in the motor (corresponding to the compressor motor 21), and the electrolytic capacitor 5 is heated by the refrigerant. With this additional configuration, the inverter device 122 according to the embodiment has the effect of being able to heat the electrolytic capacitor 5 without increasing the number of components of the inverter device 122.

[0081] Furthermore, the inverter device 122 according to the embodiment has an additional configuration in which the control unit 32 heats the electrolytic capacitor 5 if the temperature of the electrolytic capacitor 5 is below the first threshold when a predetermined first detection time has elapsed since voltage was no longer applied to the motor (corresponding to the compressor motor 21), and heats the electrolytic capacitor 5 if voltage is no longer applied to the motor and the temperature of the electrolytic capacitor 5 is below the second threshold when a predetermined second detection time has elapsed since determining whether the temperature of the electrolytic capacitor 5 is below the first threshold, the second detection time being shorter than the first detection time. With this additional configuration, the inverter device 122 according to the embodiment has the effect of being able to reduce the capacity of the memory 321.

[0082] Moreover, the refrigeration cycle apparatus 100 according to the embodiment further includes, as an additional component, a temperature detection unit 30 that detects the temperature of the electrolytic capacitor 5. With this additional component, the refrigeration cycle apparatus 100 according to the embodiment has the advantage of being able to quickly obtain the temperature of the electrolytic capacitor 5.

[0083] Furthermore, the refrigeration cycle apparatus 100 according to the embodiment has an additional configuration in which heating of the electrolytic capacitor 5 is stopped when the temperature of the electrolytic capacitor 5 becomes equal to or higher than a first threshold value. With this additional configuration, the refrigeration cycle apparatus 100 according to the embodiment has the effect of being able to accurately control the temperature of the electrolytic capacitor 5.

[0084] Furthermore, the refrigeration cycle apparatus 100 according to the embodiment has an additional configuration in which the refrigerant before compression that is drawn into the compressor 121 is heated by heat generated in the motor (corresponding to the compressor motor 21), and the electrolytic capacitor 5 is heated by the refrigerant. With this additional configuration, the refrigeration cycle apparatus 100 according to the embodiment has the effect of being able to heat the electrolytic capacitor 5 without increasing the number of components of the inverter device 122.

[0085] Furthermore, the refrigeration cycle apparatus 100 according to the embodiment has an additional configuration in which the control unit 32 heats the electrolytic capacitor 5 if the temperature of the electrolytic capacitor 5 is below the first threshold when a predetermined first detection time has elapsed since the motor (corresponding to the compressor motor 21) stopped, and heats the electrolytic capacitor 5 if no voltage is being applied to the motor and the temperature of the electrolytic capacitor 5 is below the second threshold when a predetermined second detection time has elapsed since determining whether the temperature of the electrolytic capacitor 5 is below the first threshold, the second detection time being shorter than the first detection time. With this additional configuration, the refrigeration cycle apparatus 100 according to the embodiment has the effect of reducing the capacity of the memory 321.

[0086] Furthermore, as an additional configuration, the refrigeration cycle apparatus 100 according to the embodiment has a configuration in which the refrigerant before compression drawn into the compressor 121 is heated by heat generated in the motor (corresponding to the compressor motor 21), and the refrigerant heats the electrolytic capacitor 5. With this additional configuration, the refrigeration cycle apparatus 100 has the effect of suppressing stagnation of the refrigerant before compression due to the low temperature environment around the compressor 121.

[0087] Furthermore, the inverter control method according to the embodiment further includes, as an additional configuration, a third step in which, when the temperature of the electrolytic capacitor 5 becomes equal to or higher than the first threshold value, the control unit 32 terminates heating of the electrolytic capacitor 5. With this additional configuration, the inverter control method according to the embodiment has the effect of being able to accurately control the temperature of the electrolytic capacitor 5.

[0088] Furthermore, as an additional feature, the inverter control method according to the embodiment heats the electrolytic capacitor 5 with the refrigerant, and the refrigerant is heated by heat generated in the motor (corresponding to the compressor motor 21) before being compressed and drawn into the compressor 121. With this additional feature, the inverter control method according to the embodiment has the effect of being able to heat the electrolytic capacitor 5 without increasing the number of components of the inverter device 122.

[0089] Furthermore, the inverter control method according to the embodiment has an additional configuration in which the first step is performed when a predetermined first detection time has elapsed since the motor (corresponding to the compressor motor 21) has stopped, and the second step is performed when a predetermined second detection time, which is shorter than the first detection time, has elapsed since the first step. With this additional configuration, the inverter control method according to the embodiment has the effect of reducing the capacity of the memory 321.

[0090] Although the refrigeration cycle device according to the embodiment has a four-way valve and is configured to be able to switch between cooling operation and heating operation, this is not limiting. The refrigeration cycle device may not have a four-way valve and may be configured to perform only cooling operation or only heating operation.

[0091] Furthermore, although the compressor in the refrigeration cycle apparatus according to the embodiment is a scroll compressor, the compressor is not limited to this. The type of compressor is not limited as long as the refrigerant before being drawn into the compressor passes around the compressor motor.

[0092] Although the AC power supply connected to the inverter device according to the embodiment is three-phase, this is not limiting. The inverter device may be configured to be connected to a single-phase AC power supply. Furthermore, although the compressor motor according to the embodiment has three phases, this is not limiting. For example, the inverter device may have a single phase.

[0093] Furthermore, although the temperature detection unit of the inverter device according to the embodiment is configured to detect the temperature of the electrolytic capacitor, the present invention is not limited to this. For example, the temperature detection unit may be configured to detect the temperature around the electrolytic capacitor. Furthermore, the temperature of the electrolytic capacitor may be estimated from the temperature around the electrolytic capacitor detected by the temperature detection unit.

[0094] Furthermore, although the temperature detection unit of the inverter device according to the embodiment is configured to detect the detected temperature at regular time intervals, this is not limiting and the temperature detection unit may be configured to detect the detected temperature after receiving a command from the control unit.

[0095] Furthermore, although the inverter device according to the embodiment is configured to heat the electrolytic capacitor with pre-compressed refrigerant that is heated using Joule heat generated by the compressor motor, the present invention is not limited to this. The electrolytic capacitor may be heated by other methods. For example, the pre-compressed refrigerant may be heated by providing a heater near the compressor. Furthermore, instead of heating the electrolytic capacitor with the refrigerant, the electrolytic capacitor may be directly heated. Furthermore, the electrolytic capacitor may be heated by a combination of these methods.

[0096] Furthermore, although the inverter device according to the embodiment includes a voltage detection unit, the present invention is not limited to this. The location of the voltage detection unit is not limited as long as the inverter device control unit can receive the voltage value applied to the compressor motor. Furthermore, the voltage detection unit is not limited to a voltmeter, and may be a voltage sensor or a multimeter.

[0097] Furthermore, the inverter device according to the embodiment determines that the compressor motor is not operating when the voltage value applied to the compressor motor is 0, but this is not limiting. For example, the inverter device may be configured to determine that the compressor motor is not operating when the voltage value applied to the compressor motor is less than a predetermined voltage reference value.

[0098] Furthermore, although the inverter device according to the embodiment is configured to use the voltage value detected by the voltage detection unit to determine whether the compressor motor should be driven, this is not limiting. The inverter device may be configured to determine whether the compressor motor should be driven based on an index other than the voltage value. For example, the inverter device may be configured to determine whether the compressor motor should be driven based on the current value of the compressor motor, the sound or vibration emitted by the compressor motor, or the output of an encoder.

[0099] Furthermore, although the inverter device according to the embodiment has a configuration including a temperature detection unit, the configuration is not limited to this. The location of the temperature detection unit is not limited as long as the control unit of the inverter device is configured to receive the temperature of the electrolytic capacitor.

[0100] Furthermore, although the control unit of the inverter device according to the embodiment is configured as a single device, this is not limiting. For example, the component corresponding to the storage unit may be configured as an independent device as a storage device.

[0101] Furthermore, although the inverter device according to the embodiment is configured to operate in the heating operation mode until the temperature of the electrolytic capacitor reaches the first threshold, this is not limiting. For example, the inverter device may be configured to operate in the heating operation mode for a predetermined period of time. This configuration eliminates the need to detect the temperature while the heating operation mode is in operation, thereby reducing the memory capacity.

[0102] Furthermore, the inverter device according to the embodiment is configured to receive the detected temperature after determining whether the compressor motor should be driven at each first detection time or each second detection time, but is not limited to this. For example, the control unit of the inverter device may be configured to constantly determine whether the compressor motor should be driven, and receive the detected temperature when the compressor motor has been stopped for a predetermined time or longer.

[0103] Furthermore, although the inverter device according to the embodiment drives a compressor motor, the invention is not limited to this and can be applied to devices that drive devices other than compressor motors.

[0104] The configurations described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure.

[0105] 2 Rectifier, 3 Reactor, 4 Diode, 5 Electrolytic capacitor, 6 Resistor, 10 Converter, 11 Film capacitor, 12 Inverter, 20 Intake port, 21 Compressor motor, 21a Stator, 21b Rotor, 22 Drive shaft, 23 Compression chamber, 24 Discharge port, 30 Temperature detection unit, 31 Voltage detection unit, 32 Control unit, 50 AC power supply, 100 Refrigeration cycle device, 110 Indoor unit, 111 Indoor heat exchanger, 112 Indoor blower, 120 Outdoor unit, 121 Compressor, 122 Inverter device, 123 Pressure reducing device, 124 Outdoor heat exchanger, 125 Outdoor blower, 126 Four-way valve, 130 Refrigerant piping, 310 Transmitter / receiver, 311 Temperature determination unit, 312 Drive determination unit, 313 Signal determination unit, 314 Storage unit, 320 processor, 321 memory, 322 storage, 323 hardware interface.

Claims

1. An inverter device comprising: an electrolytic capacitor that smooths an input voltage to generate a DC voltage; an inverter unit that generates an AC voltage from the DC voltage to drive a motor; and a control unit that controls heating of the electrolytic capacitor, wherein the control unit heats the electrolytic capacitor if the temperature of the electrolytic capacitor is less than a predetermined first threshold when no voltage is applied to the motor, and heats the electrolytic capacitor if, after determining whether the temperature of the electrolytic capacitor is less than the first threshold, no voltage is applied to the motor and the temperature of the electrolytic capacitor is less than a second threshold that is a value smaller than the first threshold.

2. The inverter device according to claim 1, further comprising a temperature detection unit for detecting the temperature of the electrolytic capacitor.

3. The inverter device according to claim 1 or 2, wherein heating of the electrolytic capacitor is terminated when the temperature of the electrolytic capacitor reaches or exceeds the first threshold value.

4. The inverter device described in any one of claims 1 to 3, wherein the control unit heats the electrolytic capacitor if the temperature of the electrolytic capacitor is below the first threshold when a predetermined first detection time has elapsed since detecting a state in which no voltage is being applied to the motor, and heats the electrolytic capacitor if no voltage is being applied to the motor and the temperature of the electrolytic capacitor is below the second threshold when a predetermined second detection time has elapsed since determining whether the temperature of the electrolytic capacitor is below the first threshold, and the second detection time is shorter than the first detection time.

5. A refrigeration cycle apparatus comprising: a compressor that compresses a refrigerant; an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant; a pressure reducing device that reduces the pressure of the refrigerant; an indoor heat exchanger that exchanges heat between indoor air and the refrigerant; refrigerant piping that connects the compressor, the outdoor heat exchanger, the pressure reducing device, and the indoor heat exchanger to form a refrigerant circuit; an inverter device that drives a motor of the compressor; an electrolytic capacitor that smooths an input voltage to generate a DC voltage; an inverter unit that generates an AC voltage from the DC voltage to drive the motor; and a control unit that controls heating of the electrolytic capacitor, wherein the control unit heats the electrolytic capacitor if the temperature of the electrolytic capacitor when no voltage is applied to the motor is less than a predetermined first threshold, and heats the electrolytic capacitor if, after determining whether the temperature of the electrolytic capacitor is less than the first threshold, no voltage is applied to the motor and the temperature of the electrolytic capacitor is less than a second threshold that is a value smaller than the first threshold.

6. The refrigeration cycle device according to claim 5, wherein the refrigerant before being compressed and drawn into the compressor is heated by heat generated in the motor, and the electrolytic capacitor is heated by the refrigerant.

7. An inverter device having an electrolytic capacitor that smooths an input voltage to generate a DC voltage, an inverter unit that generates an AC voltage from the DC voltage to drive a motor, and a control unit that controls heating of the electrolytic capacitor, the inverter control method comprising: a first step in which the control unit heats the electrolytic capacitor when the temperature of the electrolytic capacitor when no voltage is applied to the motor is less than a predetermined first threshold; and a second step in which the control unit heats the electrolytic capacitor after the first step when the temperature of the electrolytic capacitor is less than a second threshold that is a value smaller than the first threshold.

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