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Motor controls, refrigeration systems and methods of motor operation and control

  • US 5,376,866 A
  • Filed: 03/26/1993
  • Issued: 12/27/1994
  • Est. Priority Date: 06/24/1974
  • Status: Expired due to Term
First Claim
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1. A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields, the method comprising the steps of:

  • simulating rotor position in accordance with the back emf condition of at least one winding;

    selectively energizing the windings in accordance with the simulated rotor position;

    sensing an underspeed condition when the motor speed is less than a minimum value for a length of time; and

    preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time.

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