Stator Design for an Axial Flux PM Motor Using Straight Teeth Core with Distributed Winding

An axial flux (or axial gap) permanent magnet (PM) motor with 48-slot/8-pole distributed winding has been developed for electric motorcycle applications. The stator core includes 48 radially laminated straight core teeth inserted into the axially laminated back yoke. The designed stator has two-layer overlapped short-pitch distributed winding arrangement to generated 8-pole field with 8 turns per slot. One simple punching die is required for the stator teeth core, and the stator back yoke core can be separately made. Hence, this stator can be easily assembled and leads to cost reduction. The rotor has surface-mounted separated PM structure with a ring-shaped back iron. A prototype with single-statorl/single-rotor configuration was made and tested. The maximum speed was 5000 rpm with 48 Vdc with field weakening control. The maximum output and torque were 11 kW at 3000 rpm and 39 Nm, respectively, with a phase current of 240 A. The maximum efficiency was 93.6 %.