Controller Design for Vector Controlled AC Induction Motor Drive using State-space Design Methodologies

Recently, Vector Control also known as Field Oriented control used in AC induction motor drive provides us of a way to control AC induction motor similar to that of a DC motor. This objective is achieved by transforming the time-varying, difficult to control stator currents into a simple time-invariant system by means of coordinate transformations. This in turn provides us with a systematical way towards designing a controller using classical control or modern state-space design methodologies. Purpose of this research is to use the latter in designing a controller towards regulating current responsible for torque response. A non-linear model of the AC Induction Motor is modeled in the rotating (d,q) reference frame for the control purposes. Then, a state feedback linearization controller was design based on the idea of “exact linearization” to transform the nonlinear model into linear state-space model, thus enabling controller design using modern state-space approach. A Linear Quadratic optimal controller and Feedback+Feedforward controller is then designed and applied to the linearized induction motor model. For comparison purposes a classical P/PI controller was also designed. Simulation is then carried out using MATLAB/SIMULINK software and results shows good current regulation by controller design using modern state –space methodologies