Upgrade of Exciter for Synchronous Generators basing on the Hybrid Excitation Concept

In the classical brushless arrangement, the field current of wound-field synchronous generators (SGs) is provided by exciters through rotating diode rectifiers. The control of the SG field current is achieved indirectly by regulating the field current of the exciter, whose excitation winding is stationary. This paper investigates the possibility to equip the exciter with hybrid excitation by adding surface-mounted permanent magnets (PMs). While a hybrid PM-field winding exciter has already been proposed in a recent work, where the selected condition was the rated no-load operation of the SG, in this paper the PMs are designed to sustain the generating set (genset) operation at a suitably selected load condition. This permits to further reduce the excitation losses of the exciter and to operate the genset even in case of full failure in the exciter field system, including the related electronic controller.