Refrigeration cycle apparatus

Abstract

A refrigerant circuit includes a compressor, an outdoor heat exchanger, a throttle device, an indoor heat exchanger, and a four-way valve, and it is configured such that refrigerant circulates therethrough. An inverter is configured to control the compressor as being variable in speed. The refrigerant circuit is configured to perform a defrosting operation in which refrigerant discharged from the compressor is introduced into the outdoor heat exchanger. The compressor includes a motor. The inverter has, as an operation mode, a speed control mode in which the motor is controlled such that a rotation speed thereof is closer to a rotation speed corresponding to a command value and an output control mode in which the rotation speed of the motor is controlled such that output from the motor is closer to a target value. The inverter is configured to operate by using the output control mode in the defrosting operation.

1 . (canceled) 
     
     
         2 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit comprising a compressor, an outdoor heat exchanger, a throttle device, an indoor heat exchanger, and a four-way valve, refrigerant circulating through the refrigerant circuit; and   an inverter to control the compressor as being variable in speed, wherein   the refrigerant circuit is configured to perform a defrosting operation in which refrigerant discharged from the compressor is introduced into the outdoor heat exchanger as a result of switching of the four-way valve,   the compressor comprises a compression mechanism portion and a motor to drive the compression mechanism portion,   the inverter has, as an operating mode, a speed control mode and an output control mode, in the speed control mode, the motor being controlled such that a rotation speed of the motor is closer to a rotation speed corresponding to a command value, in the output control mode, a current flowing through the motor being detected and the rotation speed of the motor being controlled such that output from the motor is closer to a target value,   the inverter is configured to operate by using the output control mode in the defrosting operation, and   the output control mode is selected when a value indicated by an externally provided command value becomes equal to or larger than a rotation speed upper limit value determined by a DC voltage of the inverter, a characteristic value of the motor, and a current in the motor.   
     
     
         3 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit comprising a compressor, an outdoor heat exchanger, a throttle device, an indoor heat exchanger, and a four-way valve, refrigerant circulating through the refrigerant circuit; and   an inverter to control the compressor as being variable in speed, wherein   the refrigerant circuit is configured to perform a defrosting operation in which refrigerant discharged from the compressor is introduced into the outdoor heat exchanger as a result of switching of the four-way valve,   the compressor comprises a compression mechanism portion and a motor to drive the compression mechanism portion,   the inverter has, as an operating mode, a speed control mode and an output control mode, in the speed control mode, the motor being controlled such that a rotation speed of the motor is closer to a rotation speed corresponding to a command value, in the output control mode, a current flowing through the motor being detected and the rotation speed of the motor being controlled such that output from the motor is closer to a target value,   the inverter is configured to operate by using the output control mode in the defrosting operation, and   in the defrosting operation, at time of start of defrosting, the speed control mode is selected as the operating mode, and after a certain time period has elapsed since start of defrosting, the operating mode is switched from the speed control mode to the output control mode.   
     
     
         4 . A refrigeration cycle apparatus comprising:
 a refrigerant circuit comprising a compressor, an outdoor heat exchanger, a throttle device, an indoor heat exchanger, and a four-way valve, refrigerant circulating through the refrigerant circuit; and   an inverter to control the compressor as being variable in speed, wherein   the refrigerant circuit is configured to perform a defrosting operation in which refrigerant discharged from the compressor is introduced into the outdoor heat exchanger as a result of switching of the four-way valve,   the compressor comprises a compression mechanism portion and a motor to drive the compression mechanism portion,   the inverter has, as an operating mode, a speed control mode and an output control mode, in the speed control mode, the motor being controlled such that a rotation speed of the motor is closer to a rotation speed corresponding to a command value, in the output control mode, a current flowing through the motor being detected and the rotation speed of the motor being controlled such that output from the motor is closer to a target value,   the inverter is configured to operate by using the output control mode in the defrosting operation, and   the refrigeration cycle apparatus further comprising a temperature sensor to measure a discharge temperature of refrigerant discharged by the compressor, wherein   when the discharge temperature is higher than a criterion value, the speed control mode is selected as the operating mode, and when the discharge temperature is lower than the criterion value, the output control mode is selected as the operating mode.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the motor comprises a rotor, the rotor comprising a plurality of permanent magnets and an iron core, and   the iron core includes a bridge portion, the bridge portion extending in a radial direction on a q axis located between adjacent magnets of the plurality of permanent magnets and holding positions of the adjacent magnets.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the inverter comprises a d-axis current command calculator to control an amplitude and a phase of a current in the motor, and   the d-axis current command calculator controls a current command value to set the current in the motor to a maximum rated value during the output control mode.   
     
     
         7 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the inverter detects a q-axis current in the output control mode, recognizes lowering in load torque of the compressor, and increases a speed command value for the motor based on an expression (2):
   ω* 2   =P*/Iq/k   (2),
 
   
       where ω* 2  represents the speed command value for the motor, P* represents an upper limit value of output from the motor, Iq represents a q-axis current, and k represents a constant.