Design Of A High-Speed Generator For A Helium Expansion Turbine

Abstract

This paper presents design of an ultra-high-speed generator, propelled by a helium expansionturbine. The power output of the presented generator is 5 kW at 160 000 rpm. Very highefficiency, over 95%, was achieved thanks to the use of permanent magnet synchronous machine typeand proper material selection. Special care was taken during design of the machine rotor to meet bothmechanical and electromagnetic requirements. Only high-strength materials can withstand the load.Stator sheets have to be very thin, to suppress the skin effect and eddy current losses, especially withthe 4 pole configuration. It was shown that the design process for standard, low-speed machines canbe used with the awareness of it’s limitations. Weak points of the design, which should be furtherinvestigated, were pointed out.