Comparative analysis of feedback gains for adaptive full-order observers in sensorless induction motor drives

The adaptive full-order observers have been widely and successfully applied in sensorless induction motor drives. In the design of the observer, selecting proper feedback gains is the key, and many kinds of feedback gains have been proposed in the past years, but there are very few comparative studies. This paper presents a comparative study of three classical sets of feedback gains: Proportional Poles (PP), Left Poles (LP), Complete Stability (CS). The comparative analysis is based on two aspects: the convergence rate of the flux estimation, and the stability of the speed estimation. The advantages and disadvantages of each set of feedback gains are summarized. Not only computer simulations, but also experimental results are presented to confirm the validity of the proposed analysis. For the comparison tests in the paper, the dynamic parameters of both speed estimation and controlling are set at the same value for different feedback gains.