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Intermediate Speed Control for Stepping Motor Drives

IP.com Disclosure Number: IPCOM000077323D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Barcomb, JG: AUTHOR [+3]

Abstract

Shifting from high to selectable lower speeds using closed-loop step ping motor controls is obtained without disturbing the essential elements of the closed loop, by interrupting the path between the feedback pulse and the control register so as to buffer the feedback pulse until a time equivalent to the desired speed has passed. An oscillator-controlled clock can provide this predetermined time. At clock end, if a feedback pulse has been received, the motor control emitter is allowed to advance. Assuming the motor is up to speed, the emitter feedback will always precede clock end. During acceleration, clock end is reached before the feedback but the circuitry waits for the pulse before advancing the motor control register.

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Intermediate Speed Control for Stepping Motor Drives

Shifting from high to selectable lower speeds using closed-loop step ping motor controls is obtained without disturbing the essential elements of the closed loop, by interrupting the path between the feedback pulse and the control register so as to buffer the feedback pulse until a time equivalent to the desired speed has passed. An oscillator-controlled clock can provide this predetermined time. At clock end, if a feedback pulse has been received, the motor control emitter is allowed to advance. Assuming the motor is up to speed, the emitter feedback will always precede clock end. During acceleration, clock end is reached before the feedback but the circuitry waits for the pulse before advancing the motor control register. By using a clock control system or single-shots, numerous speeds less than the normal high-speed rate can be attained. Otherwise, various speed ranges with stepper motors must be accomplished by varying the DC voltage to the motor, or by setting different emitter systems for speeds at the desired rates. This is avoided by the circuit shown which, by delaying the emitter feedback pulses a preselected time via single-shots, counters or the like, permits selection of any speed lower than the maximum closed-loop speed. As the delay is increased, the speed of the stepper motor will decrease.

The controlling element in this circuit is the optional speed control latch 10. With this latch off, the stepper motor closed-loop feedback control essentially operates in a well-known manner. That is, the feedback emitter 11 is allowed to feed through sense amplifier 12, stepper motor advance hold latch 13, AND 14, stepper advance control latch 15, and AND 16 i...