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Immunity of Stepping Motor Performance Against Parameter Variation

IP.com Disclosure Number: IPCOM000086313D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

De la Court, AW: AUTHOR

Abstract

In an open-loop control system for a stepping motor, upward and downward variations of the power supply voltage cause overshoot and undershoot, respectively, of the rotor in its move to the next position. The effect of these voltage variations is minimized by an appropriate timing of the controlling pulse sequence, causing such a decelerating torque that the rotor momentarily is brought to a standstill or even negative velocity between the start and final positions of the move.

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Immunity of Stepping Motor Performance Against Parameter Variation

In an open-loop control system for a stepping motor, upward and downward variations of the power supply voltage cause overshoot and undershoot, respectively, of the rotor in its move to the next position. The effect of these voltage variations is minimized by an appropriate timing of the controlling pulse sequence, causing such a decelerating torque that the rotor momentarily is brought to a standstill or even negative velocity between the start and final positions of the move.

Overshoot and undershoot due to variations of the supply voltage result in oscillations which increase the time in which the rotor reaches the relatively stable position, required to start the next move. The time for reaching rotor stability at voltages above and below nominal is substantially decreased by performing each move of the rotor in more than one operation. The timing of the usual controlling pulse sequence is chosen such, that the rotor initially is accelerated, then decelerated to nearly standstill or even negative velocity, after which the rotor is again accelerated and stopped in the final position.

The diagrams of Figs. 1 and 2 illustrate the effect of this accelerating and decelerating procedure. Fig. la-c shows rotor movement as a function of time for a normal four-pulse sequence 0-2.0-6.0-9.5 msec at 21V, 24V and 27V, respectively. The perfect stop at the nominal voltage of 24V in Fig. 1b is highly sensitive to voltage variations, as apparent from Fig. 1a and 1c.

Figs. 2a-c shows rotor moveme...