Torque optimized speed control of a 3-phase induction motor

Abstract

A novel technique for speed control of a 3-phase induction motor (IM) based on optimal preview control theory is implemented in this paper. The vector method is adopted to synthesize a model for the 3-phase IM. This model comprises three-input variables and three-output variables which coincide with the synchronous reference frame. The input variables of this model are the stator angular frequency and the two components of the stator space voltage vector while the output variables are the rotor angular velocity and the two components of the stator space flux linkage. The objective of the proposed controlled system is to achieve motor speed control, field orientation control and constant flux control. A new error system is introduced into the control law to increase the robustness of the system. The preview feed-forward steps of the desired signal and disturbance signal are used to improve the transient response of the system. A space vector PWM control technique for a voltage source fed IM is prepared for microprocessor based control. Spectral analysis of the output voltage is evaluated to predict the effect of the proposed space vector modulation (SVM) technique on the dynamic performance of the IM. The optimal preview controlled system is synthesized and its applicability and robustness are demonstrated by digital computer simulation results.