Analytical 3-D design of a Transverse Flux Machine with high power factor

Abstract

Low-speed high-torque applications, e.g. wind energy generation, favor high number of pole solutions. for traditional radial or axial flux machines this leads to an increase in leakage flux while the power output does not increase. For Transverse Flux Machines (TFM) the increase in power output is proportional to the number of poles. However, large flux leakage is also present in TFMs, reducing their power factor and commercial application. Fast and accurate 3-D models are required to model this flux leakage. Finite Element Models (FEM) comprising a large number of elements are commonly used to calculate the 3-D flux density distribution. This approach is very time consuming with hours for a single solution. A fast and more accurate parameterized model is essential to minimize the machine volume while maintaining the required power factor. In this paper, a design approach is presented to obtain a TFM of a minimum volume with a predefined power factor. An analytical 3-D magnetic charge model is used to model a single magnetic period of the TFM. With the required power factor and the obtained flux due to the magnets the coil dimensions are calculated. The performance of the single magnetic period of the TFM is used to determine the full machine dimensions.