Semi-analytical 3-D magnetic charge model for force calculation of a Transverse Flux Machine

Modeling the 3-D flux patterns within Transverse Flux Machines (TFM) is one of the main challenges during their design. The analysis and design are often based on 3-D Finite Element Methods (FEM). Analytical models of TFMs are mostly limited to Magnetic Equivalent Circuits (MEC). This paper uses an analytical magnetic charge model to calculate the 3-D flux density in the air gap. An iterative approach allows for the modeling of flux focussing, resulting in a semi-analytical solution. Including flux focussing in the magnetic charge model results in a highly accurate prediction of the magnetic flux density in the air gap with less than 10% error. Furthermore, the cogging and attraction force of the machine are calculated for four topologies.