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Brushless DC spindle motor startup control

  • US 5,530,326 A
  • Filed: 07/19/1993
  • Issued: 06/25/1996
  • Est. Priority Date: 07/19/1993
  • Status: Expired due to Term
First Claim
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1. A multi-mode control method for controlling startup of a polyphase brushless DC motor comprising the steps of:

  • determining with a programmed digital microcontroller an angular position of a rotor of the DC motor having a first plurality of permanent magnets and magnetic poles, and a stator having a core defining a second plurality of pole segments generally facing the magnetic poles and phase windings formed around the pole segments during a first operational mode,generating an initial commutation sequence characterized by a non-linear commutation ramp for the phase windings of the DC motor with the programmed digital controller based upon determined angular position of the rotor,applying the initial commutation sequence to the phase windings to start rotation of the rotor in a forward direction, without reverse rotation, with rotor angular position leading electrical phase angle of the initial commutation sequence,monitoring back-EMF induced in the phase windings to determine rotor angular position relative to the initial commutation sequence to determine a cross-over between rotor angular position and electrical phase angle of the initial commutation sequence during a second operational mode, andgenerating a back-EMF commutation sequence with a motor controller from monitored back-EMF and commutating the motor with the back-EMF commutation sequence following the cross-over, during a third operational mode.

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