Comparative Study of Dual-Rotor Slotless Axial-Flux Permanent Magnet Machines With Equidirectional Toroidal and Conventional Concentrated Windings

Axial-flux permanent magnet (AFPM) machines are gaining popularity in low-speed and high torque applications due to their density, efficiency, compact structure. In this article, a dual-rotor slotless AFPM (DRSAFPM) machine equipped with equidirectional toroidal winding (EDTW) is proposed compared that conventional single-layer double-layer concentrated windings (CWs). First, the differences between DRSAFPM EDTW CWs coil layout, electromotive force (EMF), magnetomotive revealed. Considering special layout of EDTW, factor size equations presented. Second, electromagnetic performance including air-gap field, back-EMF, torque, efficiency analyzed based on three-dimensional finite-element method. The simulation results validate correctness indicate EDTW–DRSAFPM has superiority back-EMF amplitude density. Finally, prototype manufactured tested, which validates feasibility analysis.