In an axial gap motor, 3D electromagnetic field simulation is necessary because the magnetic flux passing through the facing rotor and stator is a 3D magnetic circuit.
In this example, presents an example of cogging torque analysis of an axial gap type motor.
Cogging Torque Waveform
This result shows that the amplitude is approximately 0.044 Nm. The cogging torque period is determined by the number of slots and the number of poles. Since this analysis target has 8 poles and 6 slots, the cogging torque period is 15 deg obtained by dividing 360 by 24, the least common multiple of 6 and 8. The torque waveform result is periodic and has a period of 15 deg as well, and since the coils are not excited the torque waveform has half-wave symmetry.
Magnetic Flux Density Distribution
The symmetry of the magnetic flux density distribution seen at the rotation angle of 0 deg is not seen at the rotation angle of 3.75 deg. Cogging torque is generated by this phenomenon.