Motor temperature control technique with temperature override

A method of temperature management of a motor drivingly coupled to a compressor of a chiller system, the method comprising:

• monitoring, via a temperature sensor, a temperature of the motor drivingly coupled to the compressor in a refrigeration loop of the chiller system including a condenser, wherein refrigerant is provided from the condenser to the motor for cooling of the motor;
• controlling, via a motor temperature control system, opening and closing of a motor cooling valve through which the refrigerant flows from the condenser to the motor to regulate an amount of the refrigerant introduced into the motor based on a set point for the temperature of the motor, a first temperature threshold, and a second temperature threshold lower than the first temperature threshold;
• switching, via the motor temperature control system, between the opening and the closing of the motor cooling valve based on an open command and a close command;
• and
• proportionally limiting the close command provided to the motor cooling valve, via the motor temperature control system, based on the temperature of the motor exceeding the second temperature threshold to limit the closing of the motor cooling valve.

A motor temperature control system for a motor coupled to a compressor of a chiller system, wherein the motor temperature control system is configured to couple to a motor cooling valve to regulate an amount of refrigerant introduced into the motor from a condenser of the chiller system according to a temperature control scheme, wherein the motor temperature control system comprises:

• memory circuitry storing the temperature control scheme;
• and
• processing circuitry configured to implement the temperature control scheme, wherein the temperature control scheme comprises:
• a monitored temperature of the motor;
• a first temperature threshold;
• a second temperature threshold lower than the first temperature threshold;
• a motor cooling control process configured to alternate the motor cooling valve between opening and closing based on an open command and a close command for the motor cooling valve;
• and
• a proportionally limited close command override of the close command that proportionally limits the close command for the motor cooling valve based on the monitored temperature of the motor exceeding the second temperature threshold to limit closing of the motor cooling valve.