Multilayer approach to the analysis of single-sided linear induction motors

Among linear electric motors, single-sided linear-induction motors (s.l.i.m.s) with sheet on solid-back-iron secondary have been generally preferred for low-speed drives and, in the last few years, they are considered one of the most probable alternative for the propulsion of some of the medium and high speed vehicles of the near future. Although a precise assessment of the performance of s.l.i.m.s is necessary, this seems to be a difficult task because of the presence of longitudinal-, and transverse-edge effects together with skin, and saturation effects in the back iron of the secondary. The literature in the field ignores one or two of the above mentioned phenomena. The present paper strives to present a complete theory of s.l.i.m.s and at the same time takes into account the specific phenomena mentioned earlier. The theory is based on the double Fourier series decomposition of the primary magnetomotive force (m.m.f.). The back iron of the secondary is notionally split into thin sheets of constant permeabilities which are determined by means of an underrelaxed iterative procedure. The theory has shown good agreement with results obtained from tests performed on an arch-type primary with a large diameter-wheel secondary.