Speed Sensorless Variable Structure Control of PMSM

Digital implementation of algorithms, designed for speed sensorless control is accounted for in the control design. For that reason, the transformation from rotating to stationary frame is achieved using rotor flux itself instead of rotor flux angle. The stability of presented model based rotor flux observer is proved by Lyapunov stability criteria. Both, the observer and the control system is tested especially at low speed with simulations and experiments