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Current control in brushless DC motors

  • US 9,548,684 B1
  • Filed: 10/04/2014
  • Issued: 01/17/2017
  • Est. Priority Date: 11/23/2011
  • Status: Active Grant
First Claim
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1. An apparatus comprising:

  • an H-bridge configured to couple a direct current power source to windings of a motor, wherein the H-bridge comprises a plurality of switches; and

    a motor controller configured to;

    close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings are short circuited,identify a desired direction for a current impulse to the windings, wherein identifying the desired direction comprises indicating to increase or decrease a magnitude of a current in the windings while maintaining a positive direction of the current,open the one of the plurality of switches in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings, andclose another of the plurality of switches in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings,wherein;

    the close of one of the plurality of switches, the open of the one of the plurality of switches, and the close of another of the plurality of switches are configured to reduce ripple currents relative to the ripple currents that would be present with pulse width modulation, andthe current impulse increases or decreases the magnitude of the current in the windings once per a duty cycle while maintaining the positive direction of the current.

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