Axial-flux hybrid-excitation synchronous machine: Analysis, design and experimental evaluation

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.