Initial rotor angle detection of a nonsalient pole permanent magnet synchronous machine

This paper presents a technique that calculates the absolute angular position of a permanent magnet (PM) rotor within a pole pair at standstill. The algorithm works with nonsalient pole motors. By choosing an appropriate voltage pulse width and applying it to each phase winding, the stator currents partially saturate the stator iron, enabling the algorithm to discern between a north pole and a south pole, and subsequently, the absolute position. The scheme is computationally simple and does not rely on the knowledge of any of the motor parameters.