Experimental comparison between field oriented control and passivity based control of induction motors

In this paper, an experimental comparison of two nonlinear controllers for flux and torque control of an induction motor is presented, namely the passivity based control (PBC) and the direct field oriented control (DFOC) methods. The principal differences between these methods are that PBC does not require state observers or estimators, requiring thus a reduced computational effort, and DFOC require all states measurements, hence, the inclusion of an observer or an estimator is needed for practical implementation. The comparison shows controller yields in satisfactory speed regulation, and load disturbance rejection. It is also shown that these two control methods are sensitive to uncertainty in the rotor time constant of the induction motor, and then motor flux and torque are not well controlled when this time constant is not exactly known