Thermal analysis and experimental verification of a staggered-teeth transverseflux permanent-magnet linear machine

To overcome the inherent demerit of low power factor existing in transverse-flux permanent-magnet (TFPM) machines, a tubular staggered-teeth TFPM linear machine is presented here. Linear alternator integrated with free-piston Stirling engines could offer a great potential in a wide variety of applications ranging from solar energy generation to space power supply. The thermal behaviour of the machine is studied using a three-terminal lumped-parameter thermal network (LPTN) to solve the problem of temperature overestimation of the traditional LPTN. The determination of thermal resistances and thermal parameters are introduced in detail. The temperatures of various components of the machine under different load conditions are calculated by both the three-terminal LPTN model and the numerical thermal model. Sensitivity analysis is carried out to study the influence of critical thermal parameters on the temperature rise of the machine. On this basis, the effectiveness of the forced air cooling is investigated. A prototype is fabricated and temperature experiment indicates that there is a good agreement between measurement and calculation.