| 摘要 |
PURPOSE:To obtain a three-phase synchronous motor having reduced fluctuation of torque, by shortening the circumferential width of each pole or the slot pitch. CONSTITUTION:Width L' of each permanent magnet 12 is set to be shorter by (slot pitch l/number of pole P) than three times the slot pitch l of stator 26. Consequently, facing condition between each pole 12 of rotor 24 and each slot 14 of the stator 26 changes for different circumferential position of the stator 26, and variation rate of flux crossing with respective phases is settled at approximately constant level. Similar effect can be achieved when the slot pitch l of the stator 26 is shortened by 1/3P for the number of poles P. Since output torque from three-phase synchronous motor is proportional to a sum of products of flux variation rates of respective phases and synchronous currents, variation of torque is reduced when the flux variation rate is constant and the magnitude of torque is not lowered.
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