A position observer for permanent magnet synchronous motor drive

A fast position observer using current measurements and a slow generic velocity estimator is proposed for a permanent magnet synchronous motor drive. An iterative algorithm is used. Assuming that the velocity is approximately constant over the transient period of the position observer, we get a linearised state model which is used to estimate the position. The observed position has two important properties. The position error is bounded by the velocity error. The derivative of the observed position, under mild assumptions, gives the actual velocity. Thus an accurate velocity estimate can be generated which in turn is used to improved the position estimate. Experimental results are presented