US Patent 7906931 Control of a switched reluctance machine

The windings of a switched reluctance machine are supplied from a converter which is capable of providing bipolar energization. The energization pattern supplied to the windings is dependent on the number of stator and rotor poles in the machine and is selected to produce unipolar energization in the rotor poles. This in turn reduces the losses in the rotor which would otherwise result from bipolar energization. The machine may also be operated to provide energization patterns which are adapted to provide optimum performance in different parts of its operating speed range.