Case Study: Vibration analysis for the design of a high-speed generator for a turbo-electric hybrid vehicle

Abstract The project relates to the design and development of a prototype high-speed turbo-generator as the thermal engine in a series hybrid vehicle. The substantial benefit of the turbo-generator against a diesel generator lies in the very high power-weight, power-volume ratio and renders itself particularly attractive for use in hybrid vehicle applications. However, to achieve a 50 kW power output, the turbo-generator has to have an operating speed of 60 000 r/min and thus important mechanical problems have to be solved. The core of this study addresses the requirement for an adequate understanding of rotor-dynamic behaviour by combining the results from both analytical and practical techniques. The assessment of modal testing, finite element analysis and vibration-condition monitoring, their feedback within the design-make-and-test procedure and the practical compromises and design constraints are presented and a design methodology is formulated. It is concluded that, under certain conditions, the prototype generator can be directly coupled to a small gas turbine, can operate safely and can produce the required power output.