Browse Prior Art Database

Motor Control Circuit

IP.com Disclosure Number: IPCOM000098128D
Original Publication Date: 1960-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Allen, FK: AUTHOR

Abstract

The circuit operates from an A.C. source to provide controlled unidirectional current for operating, selectively in either direction, a fractional horsepower D. C. motor having permanent magnet field poles or a separately excited field.

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Motor Control Circuit

The circuit operates from an A.C. source to provide controlled unidirectional current for operating, selectively in either direction, a fractional horsepower D. C. motor having permanent magnet field poles or a separately excited field.

A.C. is provided from a source 1 through a transformer 2 to a closed circuit comprising transformer secondary 3, transistors 4 and 5 and the armature winding of a D.C. motor 8.

With the transistors 4 and 5 connected back to back by the respective emitters 6 and 7, the two diodes formed by the collectors 9 and 10 and the base electrodes 11 and 12 normally prevent any flow of current in the closed circuit.

During alternate half cycles of the A.C., a controlled biasing means including a reversible switch 13 and a transformer 14 so bias both of the transistor emitter circuits as to prevent conduction. During the other alternate half cycles, the emitters 6 and 7 are biased positively with respect to the base electrodes 11 and 12 and a controlled current is passed by that transistor 4 or 5 which would normally operate as a blocking diode. Therefore, with proper biasing applied between the emitter and base of the other transistor, a controlled current is permitted to flow through the motor 8.

By selectively operating the switch 13, a selected one of the transistors 4 or 5 is biased into controlled conduction during alternate half cycles.

Similarly, a full wave rectifier circuit may be constructed using four transist...