On the analytical prediction of the force production capability of a quasi-Halbach PM excited T-LSM

The paper is devoted to an analytical prediction of the force production capability of a quasi-Halbach PM excited tubular-linear synchronous machine (T-LSM). To start with, the air gap flux density is derived considering both PMs excitation and armature magnetic reaction. The no-load operation is then characterized with the prediction of the back-EMFs and the cogging force. The obtained results are validated by 2D finite element analysis (FEA). Accounting for the armature magnetic reaction, the analytical model makes it possible the prediction of the developed force with emphasis on its synchronizing and reluctant components. The study is extended to an investigation of the effects of two major design ratios: (i) the radially-magnetized PM width to the pole pitch ratio, and (ii) the stator slot opening to the stator tooth shoes opening ratio, on the developed force mean value and ripple. This enables the selection of an optimized T-LSM design for which an investigation of the force-displacement characteristics is carried out for different values of the maximum current density. The analyticallypredicted characteristics are validated by 2D FEA.