Prediction of the air gap flux density distribution of a T-LSM with quasi-Halbach magnetized PMs: Application to the cogging force minimization

Abstract

The paper is aimed at a dual sizing-based approach to minimize the cogging force of a tubular linear synchronous machine (T-LSM) with quasi-Halbach magnetized PMs in the mover. The study is initiated by the prediction of the spatial repartition of the no-load air gap flux density. Then, a formulation of the cogging force, based on the predicted spatial repartition of the no-load air gap flux density, is developed, considering (i) the case of an “infinite” length machine and (ii) the case of a finite length one. A case study, corresponding to an initial concept, is treated with a focus on the prediction of its spatial repartition of the no-load air gap flux density and its cogging force. With this done, the study is extended to a first cogging force reduction procedure considering the case of an “infinite” length machine. It consists in the investigation of the effects of two influent sizing parameters on the cogging force, that enables the identification of a pre-optimized concept. The cogging force of this latter is then predicted in the case of a finite length machine. The study is achieved by a second cogging force reduction procedure, consisting in a quasi-cancellation of the end effect. The prediction of the cogging force of the optimized T-LSM with quasi-Halbach magnetized PMs has clearly demonstrated the effectiveness of the proposed dual sizing-based approach.