| 主权项 |
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 (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 (402), the primary PID loop (402) including a compressor motor housing temperature sensor mounted on a motor housing surface, and a first PID controller (404) in communication with the motor housing temperature sensor, the first PID controller (404) further programmed with a motor housing temperature set point; providing a secondary PID loop (412), the secondary PID loop (412) including a stator winding temperature sensor mounted on the stator windings and a second PID controller (414) in communication with the second expansion valve (1043) and the first PID controller (404), the second PID controller (414) further programmed with a stator winding temperature set point; providing a signal indicative of the stator winding temperature to the second PID controller (414); providing a signal indicative of the motor housing temperature to the first PID controller (404); providing a signal from the second PID controller (414) to the second expansion valve (1043) regulating refrigerant flow to the motor cooling circuit when the stator winding temperature varies from the stator setpoint temperature; providing a signal from the first PID controller (404) to the second PID controller (414) reprogramming the stator winding temperature setpoint, the stator winding temperature setpoint being dynamically calculated by the first PID controller (404) based on the signal from the motor housing temperature sensor indicative of the motor housing temperature and its variance from the motor housing temperature setpoint as a result of refrigerant flow to the motor cooling circuit. |
