Design, Development and Test of a 30 kW Oil Free, Turboalternator

This paper describes the design procedures and testing program used in the development of a 30 kW single shaft permanent magnet turboalternator with compliant foil bearing supports. The development program included design tradeoff studies assessing generator rotor and bearing configurations, design of the turbine, and packaging of the entire system. This paper also describes the test program to assess dynamics, thermal management of the system and testing to assess power output. Test results achieved with the prototype system operating to full speed and under power generating mode will be presented. A comparison between predicted and measured electrical output will also be presented up to a power generating level of 25 kWe at approximately 55,000 rpm. The excellent correlation between design and test provides the basis for scale up to larger power levels. This program demonstrates the successful integration of oil-free foil bearings, 4-pole composite wound permanent magnet alternator, thermal management capabilities and an axial flow turbine.