Use of transverse-flux machines in a free-piston generator

2014 17th International Symposium on Electromagnetic Launch Technology

Zhao

Zhang

et al. 2014

This paper deals with the design of transverse flux linear machines (TFLM) targeting electromagnetic launch (EML) applications, and the issues pertinent to its topology selection, design optimization and thermal modeling are discussed. By overall comparison of practical topologies and technologies of the TFLM, a tubular moving-magnet topology with separated flux paths is believed to be more appropriate. Design optimization is then performed to maximize the thrust force under specific volumetric constraints. It is shown that the thrust force is more sensitive to the stator segment length, instead of the magnet thickness. Regarding the overload requirement inherently in EML systems, special focus is given on the thermal characteristics of the TFLM at overload conditions, and it is proven that the machine shows appreciable overload capability. Measurements carried out on a prototype TFLM have validated the predictions.

Section: B Choice Of Moving-coil or Moving-magnetmentioning

confidence: 96%

Design considerations of transverse flux linear machines for eelectromagnetic launch applications

2014 17th International Symposium on Electromagnetic Launch Technology

Zhao

Zhang

et al. 2014

“…All rotary components, such as the crankshaft and connecting rods, are eliminated from the machine and it is hoped this has the potential to produce low mass, high efficiency generation devices. A number of alternative linear machines have been investigated for this application, including tubular permanent magnet [2,3] and transverse flux [4]. The 3.8 kW free piston engine presented in [5] is used to derive a specification upon which the machine topologies considered here can be evaluated.…”

Section: A the Free Piston Enginementioning

confidence: 99%

Optimization and comparison of linear transverse flux and flux switching machines

Baker

2016 XXII International Conference on Electrical Machines (ICEM)

Atkinson

2016

This paper investigates the design of alternative permanent magnet linear machines for use as the generator in a free piston engine. All of the machines are of a modulated pole structure with three dimensional flux flows. In transverse flux machines such as these, the current flows in a different plane to the flux path, eliminating the usual conflict between electric and magnetic loading. For a linear machine, the mass of magnets used is sensitive to whether the magnets are mounted on the stator or translator. Hence this paper compares transverse flux machines with translator mounted magnets and flux switching machines with stator mounted magnets. A three dimensional finite element analysis of each topology is run through an optimization routine in order to investigate the magnet usage, power factor and other performance criteria. It is concluded that flux switching machine is uncompetitive due to the 65% flux leakage even with improved tooth structure, moreover the transverse flux machine is shown to perform better overall, giving a better power factor, better efficiency and lower translator mass as a whole flux switching machine is not match for free piston engine applications.

“…For conventional machine designs, however, due to the space competitions between the stator teeth and armature conductors, the force density improvement is limited. In this regard, the transverse flux machine is believed to be a promising candidate, in which a higher value of force density can be achieved by increasing the number of poles, and therefore, is particularly attractive for space platform, where minimal weight and high volumetric efficiency are essentially of great importance [4]. In view of this, a tubular linear permanent magnet (PM) machine with transverse flux configuration has been presented and investigated for EML applications [5], the schematic structure of which is illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Inductances and phase coupling analysis of tubular permanent magnet machines with transverse flux configuration

2014 17th International Symposium on Electromagnetic Launch Technology

Zhao

et al. 2014

This paper performs the inductance and phase coupling analysis of a tubular permanent magnet machine with transverse flux configuration for electromagnetic launch (EML) applications. Self-and mutual-inductances are calculated by employing a frozen permeability FE technique, and the results are validated by measurement on a prototype machine. The analysis of phase coupling problem is then undertaken, and it has been shown that the tubular transverse flux machine has the merit of magnetic decoupling between phases, and thus shows a brilliant prospect in EML applications. The influence of armature reaction on the inductance is also investigated, and it indicates that at higher current, the inductance fluctuates once instead of twice within one electrical cycle, which is quite different from that in conventional machines.