Excitation advance control schemes for switched reluctance motors

A straightforward analytical expression for the optimal excitation advance (OEA) in motoring is derived. The product of this OEA and the voltage level turns out to be only dependent on the current. Although this dependency looks rather nonlinear, for not too low current levels the OEA varies about linearly with the current. Dynamic simulations on a simplified motor model yield optimal excitation lead times that match the analytically calculated optimum quite well. Both analytical and simulation results show fair correlation with measurements on the actual motor. Finally, the theoretical and simulation results form the basis of a straightforward excitation advance law with a linear dependency on the current. This excitation advance can easily be implemented in actual drives and results in only a marginal torque loss compared with the OEA.<>