Sensorless control of PMSM based on extended kalman filter

This paper proposes a sensorless control system based on extended Kalman filter (EKF) for permanent magnet synchronous motors (PMSM). The EKF equations are built in rotor flux oriented synchronous coordinate, so it can easily be used for either non-salient or salient pole motors. Inertia and other mechanic parameters are not needed in this observer. Rotor speed and position can be estimated exactly and then a sensorless control system is built. The initial rotor position and the mechanic parameters are not needed in this system. By some compensation in observer equations, the observer can be always stable and has only one expected equilibrium point. So the motor can start up from any unknown initial positions.