抄録
This paper studies properties and reducing techniques of cogging torque in brushless motors with surface permanent magnets and winding slots. Desirable combination between stator slots and magnet poles, and relation between the slots and added notches are shown. in order to minimize cogging torque, from the standpoint that cogging is mainly generated by fluctuation of 6th and 12th harmonic components in airgap magnetic energy lost by the stator slot openings.
Next, the proposed techniques are verified in the combination of poles and slots at typical 12 slots motors by using FEM simulation of two-dimensional model, and it is shown that bevelling of stator pole-tips reduces the cogging torque, especially in the motor with 12 slots and 10 poles.
Last, 6 slots and 4 poles motors with the added notches is calculated on the same 2D-FEM and it is shown that type B delivers better result in airgap magnetic flux distribution with rising part of quasi-sinusoidal waveform.
