Design of axial flux permanent magnet synchronous motor with reduced cogging torque

High yield of permanent magnet motors, made possible via the supply of excitation current by magnets, makes them highly popular. Consequently, a large number of studies have been carried out on various types of permanent magnet synchronous motors. Radial and axial flux are two basic structures in permanent magnet motors.Because of their structural advantages, axial flux permanent magnet motors are highly remarkable and nowadays are subject to many studies. However, cogging torque caused by the natural structure of the motor and an important reason of torque ripple presents a critical problem for a number of specific applications.A literature review reveals that a wide array of techniques, such as skewing magnets or stator slots, shaping magnets specifically, using commutating slots or teeth or optimization of magnet poles are applied in order to reduce cogging torque in radial flux permanent magnet motors. Some of these techniques can be applied for axial flux permanent motors. However, techniques applied on stator dramatically increase the costs. Techniques that do not cause an increase in costs and that reduce cogging torque are hence needed.This present thesis suggests low cost techniques for rotor side in order to reduce cogging torque and the effects of these techniques on cogging torque and torque ripple are analyzed seperately by 3D finite elements method. Two different rotor structures that minimize cogging torque are used to construct a motor prototype. Suggested techniques are verified experimentally by comparing 3D SEA values with test results obtained from constructed motor. It is confirmed that constructed prototype and designed rotor structure cogging torque values are similar.