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Method of Testing a Bifilar-Wound Permanent Magnet Step Motor

IP.com Disclosure Number: IPCOM000043258D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Raider, JW: AUTHOR [+2]

Abstract

A four-phase permanent magnet step motor has windings 10 and 11 wound in opposite directions on a first bobbin and windings 12 and 13 wound in opposite directions on a second bobbin. Neither bobbin has significant mutual coupling with the other. The four phases are produced by utilizing a switching arrangement to connect the windings 10 and 12, the windings 12 and 11, the windings 11 and 13, and the windings 13 and 10 in sequence. This continuously changes the polarity to cause the rotation of the motor in steps. To detect if there is a short circuit between the windings 10 and 11 or between the windings 12 and 13, a connection 14 is made between the junction of the windings 10 and 12 and the junction of the windings 11 and 13.

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Method of Testing a Bifilar-Wound Permanent Magnet Step Motor

A four-phase permanent magnet step motor has windings 10 and 11 wound in opposite directions on a first bobbin and windings 12 and 13 wound in opposite directions on a second bobbin. Neither bobbin has significant mutual coupling with the other. The four phases are produced by utilizing a switching arrangement to connect the windings 10 and 12, the windings 12 and 11, the windings 11 and 13, and the windings 13 and 10 in sequence. This continuously changes the polarity to cause the rotation of the motor in steps. To detect if there is a short circuit between the windings 10 and 11 or between the windings 12 and 13, a connection 14 is made between the junction of the windings 10 and 12 and the junction of the windings 11 and 13.

A constant current source 15 is connected to supply constant current to the windings 10 and 12 in series with Vsup, being the voltage applied across the windings 10 and 12 in the manner described in U.S. Patent 4,422,040. If no short circuit exists, then no current will flow through the induced winding 11 or 13. If there is a short circuit, then the voltage across the winding 10 or across the winding 12 will be affected by the portion of the current flowing through the winding 11 if the short is between the windings 10 and 11 or by the portion of the current flowing through the winding 13 if the short is between the windings 12 and 13. The complete motor characteristics, using back emf measurements, can be obtained through circuitry similar to that in U.S. Patent 4,422,040. This requires both the constant current source 15 and a constant velocity source. Only the winding...