Patent ID: 7583046

Claim:
For a multiphase alternating current (AC) wound field synchronous machine (WFSM) that has a stator with a selected number of poles, the WFSM having an associated exciter and multiphase AC permanent magnet machine (PMM) directly coupled to the WFSM, a method of sensing the position of a rotor in the WFSM comprising the steps of: configuring a stator for the PMM to have a number of poles that is a sub-multiple of the selected number of WFSM stator poles; inducing saliency in a rotor for the PMM; applying multiphase AC power of a selected frequency to the PMM stator; detecting at least one set of stator harmonic currents of the multiphase AC power resulting from the rotor saliency; converting the detected PMM harmonic stator currents from their multiphase coordinates to αβ coordinates; rotating the converted PMM stator currents into a reference frame for at least one selected harmonic to generate αβ coordinate harmonic current vectors; and estimating the position of the WFSM rotor based on the values of the αβ coordinate harmonic current vectors in the selected harmonic reference frame.