Equivalent EMF based position observers for sensorless synchronous machines

This paper provides a simple, robust, and universal position observer for position sensorless control of synchronous machines. The observer is designed using an equivalent EMF model of a synchronous machine or, alternately, using a sliding mode controller based on the equivalent EMF model. The sliding mode observer provides fast convergence and low sensitivity to parameter variations. Experimental results with a 5-hp Interior Permanent Magnet (IPM) machine have validated the effectiveness of the proposed equivalent EMF theory.