MATERIAL SELECTION ANALYSIS AND MAGNET SKEWING TO REDUCE COGGING TORQUE IN PERMANENT MAGNET GENERATOR

Sari

Cogging Torque is a pounding (torque opposite the direction of rotator generator)
when rotating the rotor that causes the rotor is difficult to rotate by hand and can interfere
with the rotation of the generator at the start, causing vibrations and disturbing sounds.
Cogging is a characteristic attached to a permanent magnet generator (GMP) caused by
the geometry of the generator. Cogging torque may affect start ability, generate noise and
mechanical vibrations when GMP is installed in wind turbines. Therefore cogging GMP
should be made as small as possible (coggingless), one way is to tilt (Skewing) permanent
magnet. Simulation using magnet software to know the magnitude of the cogging torque
caused by the rotation of the rotor on the generator. The cogging torque simulation results
are further validated by the starting torque on the GMP testing method using material
changes and magnetic skewing. The best magnetic slope is achieved when the magnetic
slope is 7.5 °, because in this position also the highest cogging torque (9.951905191 x
Nm) is found in model 3 material A skewing magnet (7.5º) with Cr-10 core material
and NdFeb magnetic magnet, while the lowest cogging value (1.17512009 x Nm) is
found in model 3 material A magnetic skewing (7.5º) with core material M250-35A and
permanent magnet NdFeb.
Keywords: Generator, Cogging, Skewing, Torque