Analysis of a novel Transversal Flux Machine with a tubular cross-section for Free Piston Energy Converter application

University dissertation from Stockholm : KTH

Abstract: Constantly growing need for oil, all over the world, has caused oil price to rise rapidly during the last decade. High oil prices have made fuel economy as one of the most important factors when consumers are buying their cars today. Realizing this, many car manufacturers have developed or are looking for some alternative solutions in order to decrease fuel consumption. Combining two different technologies in a vehicle, the so called hybrid vehicle, can be seen as the first step toward a better and more sustainable development. There are several different solutions for hybrid vehicles today, among the best known are the Serie Electric Hybrid Vehicle (SEHV), the Parallel Electric Hybrid Vehicle (PEHV) and the Serie-Parallel Hybrid Electric Vehicle (SPEHV).By integrating a combustion engine with a linear electric machine into one unit, a system that is called Free Piston Energy Converter (FPEC) is achieved. The FPEC is suitable for use in a SEHV. Other application areas like stand alone generator are also possible.In this report a novel Transverse Flux Machine (TFM) with a tubular cross section of the translator has been investigated. Application of the machine in a FPEC has put tough requirement on the translator weight, specific power and force density. Different configurations of the winding arrangements as well as the magne tarrangement have been investigated. It has been concluded that the buried magnet design suffers from high leakage flux and is thus not asuitable TFM concept. Instead the surface mounted magnet design has been chosen for further investigation. An analytical model has been developed and a prototype machine has been built based on the analytical results. In order to have a better understanding of the machine characteristic a 3D-FEM analysis has been performed.The results from the analytical model, FEM model and measurements are analyzed and compared. The comparison between the measured and FEM-simulated results shows very good agreement. Furthermore, the results from the analytical model indicates that it can be successfully developed for further analysis and optimization of the design to give a cost-effective solution of the novel generato for mass production.