Analysis of Integration Options for A Two-Stage Synchronous Generator

The popularity of synchronous generators over other power generating systems has dramatically increased over the last few decades. They are particularly important for applications that provides smooth excitation control and requires minimum maintenance. Brushless synchronous machines with a separate exciter is a good candidate in such cases, however, having a separate exciter machine introduces thermal difficulties and reduces the compactness of the system. To eliminate such limitations, this paper proposes a solution with a two-stage synchronous generator, where the exciter machine is integrated to the active and passive components of a wound-field synchronous generator. The methods considered and analysed in this work include, keeping the bore diameter identical for both the exciter machine and the main synchronous generator and integrating the exciter machine to a fan with 55 mm and 65 mm length. A more compact machine design with more than 40% reduction in the axial length was achieved, in conjunction with improved thermal management and increased power density.