Sensorless control of a permanent magnet synchronous machine down to near zero speed applied to position motion control

This paper presents a sensorless estimation scheme that enables a permanent magnet nonsalient pole motor to be position controlled without the aid of position or velocity feedback transducers. A closed loop state space observer using two phase current feedback measurements and two phase voltage commands provide estimates for the unmeasured states: position and velocity. The estimates can be parameter sensitive. Therefore, this paper has modeled motor parameters and proposes to perform on-line identification to enhance the output of the observer.