Modification in Method of Images for Three Dimensional Magnetic Field Analysis of a Transverse Flux Permanent Magnet Machine

Transverse flux machines (TFMs) are complex in construction and have a three dimensional flux path. Therefore, three dimensional (3D) finite element method (FEM) is usually used for the electromagnetic analysis of TFMs. Though the 3D-FEM technique is very accurate, computational time is very high. In the initial design and optimization process, fast and reasonably accurate analytical techniques are required. Method of magnetic charge along with method of images (MoI) is one of analytical techniques used to analyze single phase TFM in the literature. This paper proposes a modification in this method which improves the accuracy of the estimated air-gap flux density pattern. The comparison of the air-gap magnetic field using three methods, viz. MoI described in the literature, proposed modified MoI and 3D-FEM, is presented. It is observed that the proposed modification in MoI improves the ability to model flux focussing in MoI.