Line-start axial-flux permanent-magnet synchronous motor

This paper presents the design process of a novel axial-flux permanent-magnet (AFPM) motor capable of auto-starting. The preliminary design is a slot-less double-sided solid-rotor line-start AFPM motor with 4 poles for high torque density and stable rotation. One spaced raised ring was added to the inner radii of the rotor disc for smooth line-start motor. The design allows the motor to operate at both starting and synchronous speeds. The basic equations for the solid ring of the rotor for the proposed axial-flux permanent-magnet motor are presented. Non-symmetry of the designed motor led to its 3D time-stepping finite element analysis (FEA), which is used to evaluate the design parameters and predict the transient performance. The designed motor was fabricated and tested; sample experimental result showed good agreement with those of FEA based simulated results. The prototype motor showed excellent characteristics (high starting torque, good synchronization), and excellent steady-state performance.