Comparison of two nonlinear controllers for current-fed induction motors

We present here a theoretical and experimental comparison between two recent nonlinear controllers for speed regulation of current-fed induction motors: the passivity based controller (PBC) of [14] and the observer based adaptive controller (OBAC) of [9]. The theoretical comparison centers on robust stability and performance, which can be easily assessed for the PBC given its exponential stability property. On the other hand, we show that, (as expected from a scheme based on nonlinearity cancellations). in the face of parameter mismatch OBAC may become unstable even in the state feedback case. For our experimental studies we used standard low-cost hardware readily available in a practical application.