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Direct detection of back EMF in permanent magnet step motors

  • US 4,480,218 A
  • Filed: 03/29/1983
  • Issued: 10/30/1984
  • Est. Priority Date: 03/29/1983
  • Status: Expired due to Fees
First Claim
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1. A step motor control comprising:

  • a supply voltage for the motor;

    drive means connected to said supply voltage for orthogonally driving each of orthogonal low impedance windings of the motor;

    means for causing the current in one of said orthogonal windings to decay rapidly to zero while another of said orthogonal windings is being driven by said drive means;

    sensing means connected across said one of said orthogonal windings for directly sensing the voltage induced in said one of said orthogonal windings by the permanent magnet of the motor after the current in said one of said orthogonal windings has decayed to substantially zero.

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