A NONLINEAR SPEED OBSERVER FOR PERMANENT-MAGNET SYNCHRONOUS MOTORS

The application of vector control techniques in ac drives demands accu rate position and velocity feedback information for the current contro l and servo control loops. This paper describes a speed observer syste m suitable for use with the permanent-magnet synchronous motors as a s oftware transducer. The observer is developed from the dq model of the machine. The nonlinearities in the machine model present a problem to the observer design, and a technique employing state detection is use d to achieve global stability and consistent convergency of the observ er system. The design considerations of the observer are discussed. Th e simulations show that the performance of the observer is robust agai nst noise and parameter uncertainties.