Patent ID: 9574805
Date: 2017-02-21
CPC Classifications: F25B

Claim:
1. A method for controlling temperature of a compressor motor ( 170 ) having a motor cooling circuit, the compressor motor ( 170 ) in a refrigeration circuit ( 1014 ) comprising a compressor ( 1020 ) having a motor ( 170 ), a condenser ( 1030 ) in fluid communication with the compressor ( 1020 ), a first expansion valve ( 1040 ) in fluid communication with the condenser ( 1030 ), an evaporator ( 1050 ) in fluid communication with the first expansion valve ( 1040 ) and in fluid communication with the compressor ( 1020 ), the motor cooling circuit comprising a second expansion valve ( 1043 ) in fluid communication with the condenser ( 1030 ) and the compressor motor ( 170 ), the compressor motor ( 170 ) further being in fluid communication with the refrigeration circuit ( 1014 ) between downstream of the first expansion valve ( 1040 ) and a compressor inlet, wherein the compressor motor ( 170 ) further includes a stator ( 176 ) having windings and a rotor ( 178 ) mounted within a motor housing ( 174 ) and refrigerant fluid provided from the condenser ( 1030 ) to the motor cooling circuit as a cooling fluid through the second expansion valve ( 1043 ), wherein the improvement is characterized by: providing a primary PID loop ( providing a secondary PID loop ( providing a signal indicative of the stator winding temperature to the second PID controller ( providing a signal indicative of the motor housing temperature to the first PID controller ( providing a signal from the second PID controller ( providing a signal from the first PID controller (