SCALING AND DIMENSIONING OF SWITCHED RELUCTANCE MACHINES

A scaling law applying to a geometrically analogous series of switched reluctance machines (SRM), based on two-dimensional non-linear field analysis is presented in the paper. Ir highlights the fact that both l inear and saturated permeances per unit axial length at different roto r positions are invariant under scaling. Based on a normalized static energy conversion loop in the electric/magnetic loading plane a qualit y factor is defined which serves to calculate the average specific tor que. A simple analytic expression for predicting the quality factor of a SRM is derived which depends only on the linear permeances at two e xtreme rotor positions and the electric and magnetic loadings at the t oy point of the static energy conversion loop. This simplifies greatly the prediction of specific torque at an early design stage. Finally t he effects of air-gap dimension ratios, electric loading, magnetic gea r ratio and leakage flux on the quality factor and the specific torque in designing SRM having different magnetic gear varies are discussed.