Research On The Transverse-Flux Permanent-Magnet Linear Generator Used For Hybrid Electric Vehicles

The paper focuses on design, compare, analysis and optimization of several types of transverse flux permanent magnet (TFPM) linear generator, which was raised recent years and used for series hybrid electric vehicles (HEV) with the free piston engine combination.This article introduces the profile of electric vehicles and the advantages of the free piston engine combining with the linear generator tandem used for series HEV; then the author gives a relatively comprehensive overview based on the domestic and international research in this area. From this, it is found that the research about TFPM linear generator, which theoretically can be used for HVE very suitably, is quite few. The author gives a brief introduction of the working principle of this kind of generator, its structure and the approximate sinusoidal velocity curve of the mover. In this paper, 3 different models of TFPM linear generator were built, analyzed and optimized against 1 kW output power recur to the use of Maxwell 3D simulation software made by Ansoft Corporation. It was proved that Z type FTPM linear generator applied HEV has more obvious advantages by comparison of some parameters such as magnetic-flux leakage, armature-flux leakage and power density.In this paper, the author proposes the method that uses the simulation of the model with the mover in constant velocity motion to deduce the output of that in approximate sinusoidal velocity motion which the software can not deal with directly.Finally 1 kW Z type three-phase TFPM linear generator prototype was fabricated. As lacking of the mechanical design experience, some problems were met during the production of prototype. Finally only a two-phase electric machine was obtained, and the actual speed could only reach 2 m/s that only 1/5 of the rating speed, but these are not issues of principle, and it can be improved in the subsequent design quite easily. The test results were analyzed and it is in agreement with the simulation.Because of its larger thrust density, larger power density and partially overcoming the deficiencies of big reactance which suffers most of other types of TFPM linear generators, the author believes that it will become one of the types of promising alternative electrical machines with free-piston engine tandem used in HEV.