Energy saver control for single phase motors

摘要

A circuit is disclosed for controlling operation of a single phase electric motor to obtain maximum efficiency over a complete range of load conditions for the motor. Under conditions of less than full load, single phase motors waste electricity when full AC power is continuously supplied thereto. At less than full load, the torque requirements of a motor are reduced and therefore the flux can be reduced, thus increasing the efficiency. An electrical switch, in electrical series with the motor, is used to control the motor flux by reducing the "on time" of the switch and thereby decreasing the voltage applied to the motor. The ratio of auxiliary winding voltage to main winding voltage is the parameter used in the instant invention to provide a measure of the load condition of the motor and thus operate the electrical switch.