Abstract: A variable capacity refrigeration system includes a control scheme having three interrelated closed loops. The system includes a refrigeration system controller and at least one variable speed, electronically commutated DC motor driving a compressor. In the first closed loop, the controller supplies a speed command signal to a motor drive which governs the speed of the motor driven compressor. The speed of the compressor varies the system's capacity to condition the temperature of a comfort zone. A temperature sensor in the zone provides a temperature feedback signal to the controller to complete the first closed loop. In the second closed loop, the speed command signal from the controller is varied in response to a speed feedback signal received from a compressor drive which includes both the motor and the motor drive. The third closed loop is between the motor drive and the motor.

Abstract: A device for mounting a thermal overload protector to the motor of a hermetic refrigeration compressor. The overload protector is temperature responsive and is operative to protectively interrupt the current to the motor when the stator windings, rotor, or other heat source in the compressor overheats due to a compressor overload. The protector's mounting device is a plastic receptacle having a shield connected by an integral hinge. The hinge not only facilitates manufacturing the receptacle as a unitary part by an injection molding process, but also enables the shield to be opened for inserting the overload protector into the receptacle. The overload protector is held firmly in place by a U-shaped bracket integrally disposed inside the receptacle. A U-shaped groove runs along the inner edge of the bracket and is designed to slidingly engage protectors of various shapes. The receptacle includes an opening on one side of the protector opposite the heat retaining shield.