Virtual vectors based predictive control of torque and flux of induction motor and speed sensorless drives

In this paper, a simple scheme of predictive control of torque and flux is proposed to decrease the torque ripple and improve the flux locus distortion at low speed range in the direct torque control (DTC) of an induction motor. The concept of virtual vectors is also introduced to generate a fixed and higher switching frequency for the PWM invertor. Also, a MRAS (model reference adaptive control system) method using the modified rotor flux model is implemented to identify the rotor speed of induction motor, which can achieve wider bandwidth speed control. The simulation results show that very good dynamic response and steady state precision can be obtained with the proposed schemes, and this is confirmed by the experiments realized with a digital control structure using signal processor TMS320C32.