Refrigerant System With Stator Heater

Abstract

A refrigerant system adapted to reduce refrigerant migration therein includes a compressor and a controller. The compressor has a motor with motor windings. The motor windings are responsive to control signals to selectively generate heat in a manner that does not turn the motor. The controller selectively energizes the motor windings to generate heat based on at least one of a monitored temperature or pressure to warm the compressor.

1 . A refrigerant system adapted to reduce refrigerant migration therein, the system comprising:
 a compressor having a motor with motor windings, the motor windings responsive to control signals to selectively generate heat in a manner that does not turn the motor; and   a controller that selectively energizes the motor windings to generate heat based on at least one of a monitored temperature or pressure to warm the compressor.   
     
     
         2 . The system of  claim 1 , wherein the controller is the system controller. 
     
     
         3 . The refrigerant system of  claim 1 , wherein the controller determines a length of time during which the compressor has been inoperable and then calculates an operational time period to energize the motor windings to generate heat and/or the amount of heat desired to be generated by the motor windings based on the length of time the compressor has been inoperable. 
     
     
         4 . The refrigerant system of  claim 1 , wherein the controller calculates an operational time period during which the motor windings generate heat and/or an amount of heat desired to be generated by the motor windings based on at least one of the monitored refrigerant system temperature or pressure. 
     
     
         5 . The refrigerant system of  claim 4 , wherein the controller determines a length of time during which the compressor has been inoperable and then calculates the operational time period to energize the motor windings to generate heat and/or the amount of heat desired to be generated by the motor windings based on the length of time the compressor has been inoperable. 
     
     
         6 . The refrigerant system of  claim 1 , wherein the monitored refrigerant system temperature or pressure comprises at least one of a sensed outdoor air temperature, an outdoor coil temperature, an outdoor suction temperature, an indoor air temperature, an indoor unit return air temperature, an outdoor suction pressure, a motor stator temperature, an inverter drive temperature or an internal compressor temperature. 
     
     
         7 . The refrigerant system of  claim 6 , wherein the controller monitors the inverter drive temperature and the internal compressor temperature and selectively energizes the motor windings to generate heat based on whether at least one of the inverter drive temperature and the internal compressor temperature is less than at least one of a minimum indoor air temperature, a minimum outdoor air temperature, a minimum inverter drive temperature and a minimum internal compressor temperature. 
     
     
         8 . The refrigerant system of  claim 7 , wherein the controller monitors the inverter drive temperature and the internal compressor temperature and restricts the compressor from operating and energizes the motor windings to generate heat until the inverter drive temperature and the internal compressor temperature exceed predetermined temperatures. 
     
     
         9 . The refrigerant system of  claim 7 , wherein the controller monitors the inverter drive temperature and the internal compressor temperature at predetermined time increments based on the monitored outdoor air temperature. 
     
     
         10 . The refrigerant system of  claim 6 , further comprising a controller subassembly that monitors at least one of the motor stator temperature, the inverter drive temperature or the internal compressor temperature and selectively energizes the motor windings based on the at least one of the motor stator temperature, inverter drive temperature, or internal compressor temperature. 
     
     
         11 . The refrigerant system of  claim 6 , wherein the controller monitors the inverter drive temperature and cycles off or reduces current to the motor windings to maintain the inverter drive temperature below a predetermined temperature when the compressor is inoperable. 
     
     
         12 . The refrigerant system of  claim 1 , further comprising an inverter drive and wherein the inverter drive is refrigerant cooled and the controller operates the compressor at a minimum speed to allow for refrigerant to flow through and cool the inverter drive. 
     
     
         13 . The refrigerant system of  claim 1 , wherein the refrigerant system is configured as a heat pump, the heat pump comprising:
 a first heat exchanger in fluid communication with the compressor;   a first air circulation device positioned adjacent the first heat exchanger;   a second heat exchanger in fluid communication with the compressor and the first heat exchanger;   a second air circulation device positioned adjacent the second heat exchanger;   a reversing valve fluidly coupled between the first heat exchanger and the second heat exchanger;   an electronic expansion device fluidly coupled between the first heat exchanger and the second heat exchanger; and   an inverter drive;   wherein the controller selectively energizes the motor windings to generate heat in a manner that does not turn the motor.   
     
     
         14 . The refrigerant system of  claim 13 , wherein the controller controls at least one of the first air circulation device and the second air circulation device to render at least one temporarily operable to selectively cool the inverter drive from an overheat condition that can result from the motor windings generating heat within the compressor. 
     
     
         15 . The refrigerant system of  claim 13 , further comprising:
 an outdoor suction pressure sensor and an outdoor suction temperature sensor disposed adjacent the reversing valve or an accumulator and configured to output the outdoor suction pressure and the outdoor suction temperature to the controller;   a motor stator temperature sensor positioned within the compressor adjacent the motor windings and configured to output the motor stator temperature to the controller;   an inverter drive temperature sensor positioned within the inverter drive and configured to output the inverter drive temperature to the controller; and   an internal compressor temperature positioned within the compressor adjacent a compression area therein and configured to output the internal compressor temperature to the controller;   wherein the controller selectively energizes the motor windings to generate heat to warm the compressor based on at least one of the outdoor suction temperature, inverter drive temperature, the internal compressor temperature, or the motor stator temperature.   
     
     
         16 . A method of reducing refrigerant migration to a compressor comprising:
 providing compressor having a motor with motor windings responsive to control signals to selectively generate heat in a manner that does not turn the motor;   monitoring at least one of a refrigerant system temperature or pressure; and   controlling the motor windings to selectively generate heat based on at least one of the monitored temperature or pressure to reduce refrigerant migration to the compressor.   
     
     
         17 . The refrigerant system of  claim 16 , wherein the controller is the system controller. 
     
     
         18 . The method of  claim 16 , wherein the monitored refrigerant system temperature or pressure comprises at least one of a sensed outdoor air temperature, an outdoor coil temperature, an outdoor suction temperature, an indoor air temperature, an indoor unit return air temperature, an outdoor suction pressure, a motor stator temperature, an inverter drive temperature or an internal compressor temperature. 
     
     
         19 . The method of  claim 18 , wherein the controller monitors the inverter drive temperature and the internal compressor temperature and selectively energizes the motor windings to generate heat based on whether at least one of the inverter drive temperature and the internal compressor temperature is less than at least one of a minimum indoor air temperature, a minimum outdoor air temperature, a minimum inverter drive temperature and a minimum internal compressor temperature. 
     
     
         20 . The method of  claim 18 , further comprising an inverter drive electrically connected to the compressor and configured to vary the speed of the compressor, and wherein the controller monitors the inverter drive temperature and either cycles off or reduces current to the motor windings to maintain the inverter drive temperature below a predetermined temperature or operates the compressor at a minimum revolution per minute or operates a fan adjacent to the inverter to allow for cooling of the inverter drive while the motor windings generate heat.