Pole Shape-Based Reduction of the Harmonic Content of the IPM T-LSM Air Gap Flux Density

This paper presents a sizing approach dedicated to the reduction of the harmonic content of the air gap flux density of interior permanent magnet tubular-linear synchronous machines (IPM T-LSMs) based on pole shaping. The study is initiated by a formulation of the air gap flux density of conventional IPM T-LSMs equipped with flat-shaped poles. In the second step, the established model is reformulated with emphasis on the pole shape variation characterized by two parameters: the pole air gap radial width and the pole head opening. Following its experimental validation, the resulting model is applied to the sizing of the pole shape in an attempt to reduce the harmonic content of the air gap flux density. The developed sizing procedure considers the effect of the above-defined parameters on the harmonic content of both the radial and axial components of the air gap flux density. The study is achieved by the selection of a set of parameters for which both radial and axial components of the air gap flux density exhibit their lowest spatial harmonic distortion.