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Brushless DC motor sensor control system and method

  • US 6,538,403 B2
  • Filed: 12/20/2000
  • Issued: 03/25/2003
  • Est. Priority Date: 01/07/2000
  • Status: Expired due to Fees
First Claim
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1. A method for controlling a brushless DC motor including a rotor and a stator having at least three phases, the rotor being magnetically coupled to and moveable by the stator when the phases are appropriately energized, each of the phases being characterized by a corresponding voltage waveform, comprising the steps of:

  • providing no more than two position sensors for sensing a rotor position during a start-up mode, each position sensor having an associated position sensor signal;

    aligning the position sensors to sense the rotor position such that each position sensor signal indicates a zero torque point corresponding to a phase voltage waveform;

    sensing the position of the rotor such that the position sensor signals indicate a start-up operating state;

    during a first ambiguous start-up state;

    alternately energizing two predetermined phases; and

    during a defined start-up operating state;

    energizing one predetermined phase.

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