Design and Analysis of a Novel Axial-Flux Electric Machine

A novel low-speed axial-flux-modulated motor is proposed for in-wheel applications in hybrid electric vehicles. The proposed motor breaks the traditional design rule which stipulates that the pole-pair numbers of the stator and the rotor must be equal. Special ferrite segments in the air gap are used to modulate the magnetic field. It has the merit of having a very high torque density at low speed. It can be fitted into very limited space, such as inside the wheel rim of electric vehicles. Compared with radial-flux-modulated motors (RFMM), its manufacturing and assembling process are simple and easy. Its performance is compared with that of an RFMM using two-dimensional and three-dimensional finite-element methods and the comparison results verify the validity of this proposed machine design.