PLL Speed Control of Quick Torque Controlled Induction Motor with Disturbance Compensation

Abstract

This paper presents an excellent speed control scheme for the induction motor drive. The quick torque control of an induction motor is used to provide better torque characteristics. PLL technique based on PID feedback of phase difference is employed to provide extremely accurate speed regulation and the four quadrant operation is obtained by the exchange of PLL control for the constant torque control. Besides, the disturbance is estimated by the disturbance observer and its feedback eliminates the disturbance effect on speed. The system combines the advantage of the quick torque control and the precise speed regulation of PLL technique, and the insensitivity to disturbance by disturbance compensation.
An analytical model of the drive system is developed and phase plane analysis is used to evaluate effects of gain coefficients on PID feedback of phase difference and to predict the system behavior. An experimental model using a 2.2kW induction motor is built and tested. Experimental results are presented to verify the predicted system behavior.