In a permanent magnet brushless motor, airgap field excited by a 2-pole magnet ring with parallel magnetisation is sinusoidal.
永磁无刷电机中，平行充磁的2极磁环产生的气隙磁场是正弦分布的。
2
An experimental set up of travelling magnetic field excited by supper power permanent magnet was designed, which has obviously refine function for metal solidification structure.