Abstract
This paper proposes a Sensorless Field Oriented Control for surface mounted permanent magnet synchronous motor combining two approaches for different rotor speed ranges. The active flux observer is applied at low speed and combined with a back-EMF observer at high speed. This combination allows for an improvement of the rotor position estimation for a large speed range and is therefore resulting in a higher stability of the sensorless control scheme when compared to the conventional back EMF method. The presented approach is discussed based on simulations.