Vector control for induction machine on the application of optimal control theory

An approach for constructing a field-oriented control system using the state-space method is proposed. The field-oriented control system can be realized by coinciding the synchronously rotating reference frame with the axes of the secondary flux linkage reference frame and by simultaneously but independently adjusting the three control inputs. A control-system synthesis method that achieves speed control, field-oriented control, and constant flux control simultaneously is presented. The control system has a full-state feedback structure and is synthesized by applying a multi-input and multi-output optimal regulator theory. The excellent robustness of the constructed system results in zero steady-state errors for changes in parameters such as rotor resistance. The validity of the control scheme is verified by simulation studies. Results are presented for a field-oriented induction motor driven by a PWM (pulse-width modulation) inverter