Nonlinear speed observer for permanent-magnet synchronous motors

Abstract

The application of vector control techniques in ac drives demands accurate position and velocity feedback information for the current control and servo control loops. This paper describes a speed observer system suitable for use with the permanent-magnet synchronous motors as a software transducer. The observer is developed from the dc model of the machine. The nonlinearities in the machine model present a problem to the observer design, and a technique employing state detection is used to achieve global stability and consistent convergency of the observer system. The design considerations of the observer are discussed. The simulations show that the performance of the observer is robust against noise parameter uncertainties.