Winding Function Model-Based Performance Evaluation of a PM Transverse Flux Generator for Applications in Direct-Drive Systems

The magnetic flux in a permanent magnet transverse flux generator (PMTFG) is three-dimensional (3D), therefore, its efficacy is evaluated using 3D magnetic field analysis. Although the 3D finite-element method (FEM) is highly accurate and reliable for machine simulation, it requires a long computation time, which is crucial when it is to be used in an iterative optimization process. Therefore, an alternative to 3D-FEM is required as a rapid and accurate analytical technique. This paper presents an analytical model for PMTFG analysis using winding function method. To obtain the air gap MMF distribution, the excitation magneto-motive force (MMF) and the turn function are determined based on certain assumptions. The magnetizing inductance, flux density, and back-electro-magneto-motive force of the winding are then determined. To assess the accuracy of the proposed method, the analytically calculated parameters of the generator are compared to those obtained by a 3D-FEM. The presented method requires significantly shorter computation time than the 3D-FEM with comparable accuracy.