A novel back EMF observer for sensorless control of interior permanent magnet synchronous motors

The paper presents a position sensing method for IPM motors based on an observer referring to the estimated frame of reference, eliminating problems with position dependent inductances. Convergence of the estimation error to zero is proofed, under the assumption that the mechanical time constant is much larger than the electrical one. The observer can be used right from startup to rated speed, so bump from a startup strategy is avoided. In order to verify the observer experiments have been performed