Comparison of Axial Flux PM Synchronous Machines With Different Rotor Back Cores

摘要

Rotor losses of axial flux permanent magnet (PM) synchronous machines with fractional windings depend on stator magneto–motive force (MMF) harmonics. To reduce rotor losses, a soft magnetic composite rotor can be used. This paper focuses on the comparison between two machines with the same soft magnetic composite stator and different rotor cores: one of solid steel and another of soft magnetic composite. The study evidenced the composite rotor improved the power density and the efficiency. Moreover, it highlighted a nonlinear salient-pole operation of the composite rotor machine, mainly connected to spatial harmonics.