New method for speed control of single phase induction motor with improved motor performance

In this paper, a new method of speed control for the single phase induction motor is introduced to overcome the disadvantages of the conventional methods. In this method, the magnitude of the main winding current and its angle are controlled to control the motor speed, as well as to increase the starting torque at all speed settings. In the meanwhile, the voltage applied to the auxiliary winding is kept constant at the rated value. The performance of a 1 hp capacitor run single phase induction motor is experimentally and theoretically investigated, using this method of speed control. The experimental rig is built in the laboratory and a complete set of test results is obtained. On the other hand, a mathematical model for the motor is developed and the motor performance is calculated. Good agreement between the experimental and theoretical results is obtained. These results show that the new method of speed control gives much higher starting torque. This enables the motor to start at low speed settings. Also, a great improvement in motor efficiency and power factor at all speeds is achieved. (C) 2001 Elsevier Science Ltd. All rights reserved.