METHOD AND APPARATUS FOR DRIVING STEP MOTORS WITHOUT OVERSHOOT

摘要

A method and apparatus for driving a stepper motor such that when the motor is stepped, the velocity of the motor is substantially zero upon reaching a new stepped position, thereby eliminating overshoot and ringing, and the wasted energy associated with these effects. The method comprises energizing at least one of the stepper motor windings at a predetermined current level for a predetermined step time, wherein the current level is determined as a function of the step time and dynamic single-step response characteristics of the stepper motor and load so that the motor velocity is substantially zero when the adjacent stepped position is reached. At this point, the stepper motor windings that were energized to make the rotor of the motor move are de-energized, whereupon the rotor is held in place by the inherent detent torque of the stepper motor. Since the velocity of the motor is substantially zero when the adjacent stepped position is achieved, there is no overshoot, and thus ringing is eliminated.