 Image Number 8 for United States Patent #4629916.
A polyphase synchronous motor having a relatively large number of poles, constructed for substantial elimination of all significant harmonics. Harmonics are eliminated by dividing the motor into two symmetrical groupings, each a complete motor, then rotating one grouping relative to the other by an angle .pi./h electrical degrees, where h is the order of the harmonic being suppressed. Also, with a permanent magnet disc rotor, the magnet poles on one face of the disc can be rotated relative to those of the other face in the same manner, to suppress a harmonic.
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