| 摘要 |
PURPOSE:To increase an output for a unit volume by a method wherein the shape of the cross section of a permanent magnet perpendicular to the longitudinal direction is an arc shape expanding outward. CONSTITUTION:The shape of the cross section of a rotary shaft perpendicular to the longitudinal direction has arcs 3-6, whose number is the same as the number of poles and centers are identical to the center 2 of the shaft, and straight parts 7-10 connecting between the adjacent arc parts 3 and 4, 4 and 5, 5 and 6 and 6 and 3 without bending parts. The same number of permanent magnets 11-14 as the number of poles are provided. The center part of each permanent magnet is thicker than the other part and a permeance coefficient is large at the center part where the thickness Lm is large and small at the end part where the thickness L'm is small. With this variation of the permeance coefficient, a flux waveform which is high at the center part can be obtained. Therefore, the ratio of fundamental wave/total RMS becomes large so that the utilization of the flux can be improved and the controllability can be also improved.
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