A globally converging observer of mechanical variables for sensorless PMSM

This paper analyzes Matsui's paper which presented two PMSM mechanical sensorless control methods (see IEEE Trans. Ind. Electron., vol.43, no.2, p.300-308, 1996). Our studies show that the convergence of the estimated variables depends on their initial values and is not guaranteed. We propose a simple solution to start up the motor from any rotor initial position by modifying Matsui's methods. A new nonlinear model of PMSM for mechanical sensorless application is also presented. Simulation and experimental results illustrate the validity of the model and the applicability of this approach.