A simple speed control method for small induction motors base on phase difference

Some form of simple control is needed for small induction motors. This paper proposes a simple speed control method for small induction motors using a simple calculation without the need for a speed sensor. In this method, the load torque is estimated from the detected power factor of the induction motor and the speed of the induction motor is compensated for by a frequency-boost technique. The boost frequency is selected from a data table measured beforehand. Satisfactory experimental results are obtained with 90 W induction motors.