Abstract:
Axial flux Permanent Magnet (AFPM) machines, due to its high torque capability, high
power density and compact size, are the most suitable candidates for in-wheel Electric Vehicle
application. However, the presence of cogging torque in AFPM machines, resulting from the interaction
of PMs and stator slots, introduces torque ripples, noise and vibrations which deteriorates the
performance of the machine. To overcome this, several techniques for cogging reduction are utilized. Out
of various techniques, rotor magnet shape variation is most commonly utilized. This paper investigates
the effect of some preferred magnet shaping techniques in AFPM machines on several performance
parameters such as magnetic flux density distribution in air gap, cogging torque, flux linkage, no loadinduced emf, emf harmonics, electromagnetic torque and torque ripple. These parameters were analyzed
using 3-D Finite Element Method (FEM) based simulations. It was found that a maximum cogging
reduction by 62.49% and output torque ripple by 63.25% were obtained by using short-pitched and
skewed rotor magnets. This also resulted in a reduction of induced emf by 14.18% and electromagnetic
torque by 15.17%
