Direct computation of ac machine inductances based on winding function theory

A numerical procedure for computing the inductances of ac machines is described. The procedure does not require that explicit expressions for airgap or winding functions be obtained therefore complicated integrations are avoided. The effects of stator slots are included in a manner in which all the harmonics are taken into account. The inductances obtained are subsequently transformed to d-q-0 reference frame and the results are seen to compare favorably with measurements. Significant differences exist in the computed inductances especially in the d-axis. Cross-coupling effects between the d-axis and q-axis inductances which are generally ignored when approximate expressions are used are also observed.