Brushless DC drive motor with external rotor for use in disc drives and like devices

  • US 5,382,853 A
  • Filed: 10/03/1990
  • Issued: 01/17/1995
  • Est. Priority Date: 06/06/1980
  • Status: Expired due to Fees
First Claim
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1. A brushless DC drive motor of the type having a total number of phases divisible by three, comprising, in combination,a stator;

  • a permanent-magnet rotor mounted on said stator for rotation relative thereto about a rotation axis, said rotor having a total of four rotor poles of which two are of a first magnetic polarity and the other two of an opposite magnetic polarity, the rotor poles of first polarity alternating circumferentially with the rotor poles of second polarity;

    a stator winding mounted on said stator and consisting of three pairs of non-overlapping stator coils; and

    rotor-position-dependent control means connected to the three pairs of non-overlapping stator coils for controlling energization of said three pairs of non-overlapping stator coils in dependence upon angular position of the rotor, and including rotor-position-detecting means located stationary with respect to said stator and operative for detecting the angular position of the rotor,wherein each pair of stator coils consists of two coils which are located diametrically opposite to each other and which are so wound and electrically connected that both are energized substantially simultaneously with identical magnetic polarity.

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