This paper presents an axial-flux machine with hybrid excitation, in which the flux linkage can be regulated in an extremely wide range through an excitation winding. Therefore, this machine shows a theoretically infinite constant power speed range and exhibits also an high degree of fault tolerance against uncontrolled generator operation. The machine has a single-stator double-rotor topology, one rotor mounting permanent magnets and the other supporting an excitation winding. After a review of the state of the art, the paper examines the principle of operation of this machine. Subsequently, a prototype is designed, studied through FEA, and constructed, in order to verify the benefits of the proposed solution.
Axial-Flux Hybrid-Excitation Synchronous Machine: Analysis, Design and Experimental Evaluation / GIULII CAPPONI, Fabio; DE DONATO, Giulio; Caricchi, Federico Attilio. - STAMPA. - (2012), pp. 3641-3648. ((Intervento presentato al convegno IEEE Energy Conversion Congress and Exposition tenutosi a Raleigh, NC, USA nel 15-20 Settembre 2012 [10.1109/ECCE.2012.6342482].