Thermal analysis of a high-speed generator

The machine under study is a permanent magnet synchronous generator intended for operation at high speeds together with a micro-turbine in a combined heat and power (CHP) unit. Target power is 110 kW at 70000 rpm. The study is both theoretical and experimental since it includes calculation of loss distribution and thermal analysis together with calorimetric measurements of losses and temperature measurements. In this paper the thermal model is described. Using results from loss calculation and calorimetric measurements a thermal analysis is carried out. It is shown that introducing a copper screen in the rotor reduces the losses to acceptable values. A limit for the allowable rotor losses is given.