Investigation of a tubular linear transverse flux machine for use with a free-piston engine

Abstract

This thesis explores different topologies of permanent magnet linear electric machines for use with a renewable engine – Free-Piston Engine. By comparing their performances, it aims to prove that a new linear modulate pole (transverse flux) machine can be the best overall topology. Five candidate topologies including longitudinal flux and transverse flux types are presented and simulated by finite element analysis method in MagNet software. The designer optimises each topology with the same effort and strategy by using an advanced algorithm in OptiNet software. The transverse flux and flux switching topology are detailed compared with different optimisation strategies to investigate machine performances. The designer performs an advanced design study on the modulated pole machine to simplify the manufacturing process, reduce building cost and improve output performance. The process includes the tooth combination design, the single tooth winding design and the lamination design. The designer expands the insight of the final designed modulated pole machine. The force production and power factor derivation are performed theoretically and numerically. The numerical solution is compared to the simulation result for validation. Detailed mechanical design for the final designed modulate pole machine is performed consisting of: the shaft strength investigation, the stator assembly strategy, the winding assembly and drive linear actuator selection. The designer tests the final build modulate pole machine in both static and dynamic conditions. Static tests include cogging force test and DC test. Dynamic tests include EMF test and short circuit current test. All results are compared with simulations for machine quality check. The thesis demonstrates that the tubular transverse flux machine is manufacturable and fulfil the requirements of a Free-Piston Engine.