Patent ID: 7804269

Claim:
A method of operating an electrical machine, the machine having a stator defining stator poles, a rotor defining rotor poles, the rotor being movable relative to the stator so that the rotor poles are successively alignable with any stator pole, and independently energisable phase windings, each associated with at least a pair of stator poles and having an inductance cycle determined by the passage of the rotor poles past the stator poles, the method comprising: in a first mode of operation, initiating the energisation of the phase windings in a predetermined sequence and for consecutive inductance cycles of each phase in turn; and in a second mode of operation, initiating the energisation of the phase windings in the same sequence, in which initiation of energisation of each phase winding is followed by at least one inductance cycle of that phase with no initiation of energisation.