| 摘要 |
A synchronous motor includes a unitary rotor, a first stator, a second stator and phase-changing switches. The unitary rotor has a first rotor portion formed by a first permanent magnet and a second rotor portion formed by a second permanent magnet and an induction type rotor and these first and second rotor portions are mounted on a common rotary axle with a predetermined space provided therebetween. The first stator faces the first rotor portion for producing a first rotating magnetic field. The second stator faces the second rotor portion for producing a second rotating magnetic field and is disposed such that, at the starting operation, the attracting action or the repelling action produced between the first rotating magnetic field and the first permanent magnet is canceled by the repelling action or the attracting action produced between the second rotating magnetic field and the permanent magnetic field. The phase-changing switches are associated with either one of the first stator or the second stator and set a phase difference of 0 degree or 180 degrees between the first rotating magnetic field and the second rotating magnetic field. Due to the cancellation action, any starting interference which may otherwise be caused by the permanent magnets is made negligible.
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