Model-independent sensorless control for non-salient PM Synchronous Motors at low speeds including standstill

This article presents a new position and speed sensorless drive for non-salient pole PM synchronous machines in low speed range including standstill. The proposed method does not depend on the machine parameters and is very simple to implement. A voltage pulse injection is combined to a magnetic circuit saturation which will be created by an additional current. This latter is not necessary if the machine is salient pole. Mathematical proof of the convergence is presented. The minimum saliency required for sensorless operation at zero speed is determined. It is also shown that the proposed approach is robust with respect to parameter uncertainties. The effectiveness of this technique is verified by simulation and experimentation on an eight-poles 1 hp - 1000 rpm test machine.