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Speed Control for Stepper Motor

IP.com Disclosure Number: IPCOM000074314D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Greer, WM: AUTHOR

Abstract

Motor 20 is a two-phase, two-pole stepping motor driven by two-stage counter 21 connected to motor drive circuits 22. Counter 21 in turn is advanced by output pulses from single shots SS1 and SS2 connected through NAND gates 12 and 13. The speed-regulator circuit 23 comprises single shot SS3, frequency discriminator 24, comparator 25, and a polarity-hold circuit comprised of NAND gates 4 through 7 with outputs connected to NAND gates 1 and 2 connected to the inputs of single shots SS1 and SS2.

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Speed Control for Stepper Motor

Motor 20 is a two-phase, two-pole stepping motor driven by two-stage counter 21 connected to motor drive circuits 22. Counter 21 in turn is advanced by output pulses from single shots SS1 and SS2 connected through NAND gates 12 and 13. The speed-regulator circuit 23 comprises single shot SS3, frequency discriminator 24, comparator 25, and a polarity-hold circuit comprised of NAND gates 4 through 7 with outputs connected to NAND gates 1 and 2 connected to the inputs of single shots SS1 and SS2.

The circuit operates as follows: a start pulse is introduced to single shot SS1 advancing counter 21 on the recovery (positive) edge of SS1 pulse. Advancing the counter 21 causes motor 20 to rotate causing the timing-pulse generator 26 to supply a timing pulse to single shot SS3. Single shot SS3 in turn provides a pulse of constant width to the frequency-discriminator circuit 24 and also to the polarity-hold circuit of NAND 4 through 7. The output of the frequency- discriminator circuit 24 is an analog signal proportional to motor speed which is fed into the voltage-comparator circuit 25. Initially, the output of frequency discriminator circuit 24 is low and the output of the voltage comparator 25 is down. This allows the pulse from SS3 to be passed through NAND 1 thereby triggering single shot SS1. As the speed of motor 20 attempts to increase, the analog voltage from frequency-discriminator circuit 24 causes the output of voltage comparator...