Discrete position estimator for a switched reluctance machine using a flux-current map comparator

A rotor position estimator for a switched reluctance motor (SRM) employs a flux-current map to determine whether the actual rotor angle is closer to, or farther from, axial alignment of stator and rotor poles than a reference angle theta r. The flux-current map is a plot of reference flux PSI r as a function of current for the reference angle theta r. If a flux linkage estimate PSI /< ANd >i is greater than the reference flux PSI r, then the actual rotor angle is closer to alignment than the reference angle theta r, and the flux-map comparator output is a logic level one. If the flux linkage estimate PSI /< ANd >i is lower than the reference flux PSI r, then the actual rotor angle is farther from alignment than the reference angle theta r, and the flux-map comparator output is a logic level zero. When the result of the flux comparison causes the flux-current map comparator to change state, the actual rotor angle is equal to the reference angle theta r, with the result that phase currents can be successfully commutated relative to this rotor position. The flux-current map can be implemented using either single-phase or multi-phase SRM flux-current characteristics.