Investigation of cogging forces using reluctance circuits equivalent approximation in a ladder secondary single-sided linear induction motor

Abstract

Linear induction motors have recently played an important role in positioning linear motion. However, they suffer a low level of precision for very low speed application. For improving the precision of LIM, especially in very low speed application - high-performance motor - the existence of cogging forces due to the magnetic conductance of air gap variation or interactive magnetic edge and end effect variation in the ladder-secondary single-sided linear induction motor (LSLIM) should be reduced as small as possible. This paper developed two simple magnetic circuits: one-slot and multi-slot model. The cogging forces analysis will be concerned with magnetic energy variation in the air gap. Based on magnetic conductance inparalleland series structures, analysis of RCE will be done by implementation of Kirchoff law number one and number two. It shows that analytical result trends are close to the experimental results and finite element method software. This paper provides the prediction of a close form of the mathematical model of maximum cogging forces for single-side linear induction motors. So, those results can contribute one aspect in related designing a physical single or double-sided linear induction motor. The variation of flux densities in the air gap in the middle region of LSLIM can give some contribution for calculating cogging forces, and different variation of leakage magnetic path fields in the end region can reduce the magnitude of flux densities in the air gap, but cogging forces in the end region can cancel each other.