Importance

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Abstract

Electronically commutated motor and control arrangements particularly adapted for use with refrigeration systems and methods of operating refrigeration systems are disclosed. In one form, a fan control means is provided for responding to temperature of a compartment being cooled by a refrigeration system; comparing the compartment temperature with a desired temperature; and varying the speed of an evaporator fan, thereby varying the movement of refrigerated air across an evaporator and into the compartment. A regulating circuit is provided for maintaining the evaporator at a reference temperature by controlling the output signal of an alternator which supplies energization power to winding stages of a brushless DC motor. By varying the energization level of the winding stages, a compressor, which is coupled to the motor, is caused to vary the flow rate of refrigerant through the evaporator so as to maintain the evaporator at the reference temperature. The regulating circuit includes means for responding to a signal from the fan control means, which is indicative of the fan speed and relative compartment cooling demand, for changing the reference temperature for the evaporator thereby to cause variance in the temperature of air moved about the evaporator by the fan for controlling temperature within the compartment. The regulating circuit also includes: means for limiting and controlling motor winding current to a maximum value; means for limiting motor speed to a predetermined low value; means for limiting and controlling motor speed to a maximum high value; means for assuring a minimum energization level for the motor winding stages; means for limiting the energization level of the winding stages to a maximum voltage value; and means for inhibiting motor operation if the evaporator temperature is less than a predetermined low temperature value.

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First Claim