Design and analysis of axial flux permanent magnet motor for electric bicycles with hybrid stator core

Abstract

This paper proposes a new axial flux permanent magnet (AFPM) motor, whose stator is composed of laminated steel and soft magnetic composite (SMC) material. Axial flux machines are considered a preferred solution compared to radial flux machines for electric vehicles and traction applications because of its high torque density and thin disk-shaped structure. However, the manufacturing cost of axial flux machines is greater than radial flux machines due to its inherent structure. The hybrid construction of the stator core presented in this paper reduces the manufacturing complexity and fabrication cost in axial flux machines. The proposed AFPM is designed to be utilized in electric bicycles replacing the currently used radial flux brushless DC (BLDC) motor. The performance characteristics of the developed AFPM are analyzed using the 3D Finite Element Analysis (FEA) to verify the advantages of the proposed model. However, the torque ripple of the basic model of novel AFPM was high, which was reduced by adjusting rotor pole arc width (PAW) ratio, to make it viable for the commercial application. Finally, a prototype of the proposed motor was manufactured and tested in the laboratory.