Magnetic permeance of doubly-salient airgaps

Design data are presented in the form of permeance factors for the airgap between doubly-slotted surfaces, for the cases in which the teeth are perfectly aligned and symmetrically misaligned. Data previously available are thus extended to become applicable to stepping motors as well as to other types of machine, and the new data are in a more convenient form. The permeance factors are used to calculate the average force over a step length, and these results confirm the accuracy of earlier studies based on more approximate data. The effect of finite slot depth is discussed, and the solution of the troublesome implicit equations involved is obtained using a patternsearch minimisation procedure.