| The stepper motor is an electromechanical device that converts electrical pulses into discrete mechanical movements. The advantages of stepper motor are precise positioning and non-cumulative movement error from one step to the next. Compared to closed loop control, open loop operation of stepper motor is more reliable and less expensive. The disadvantages in using a step motor are vibration and noise at low speeds, resonance when the motor is operated at or around the natural resonance frequency, motor torque decreasing with speed increasing. These disadvantages limit step motor's application.Step motor cannot work without step motor driver. Its performance is close related to stepper motor driver. Traditionally, a motor driver is to provide the rated current to the motor windings in the shortest possible time, helping to maintain high speed torque. As a result, motor's vibration and noise is greater at low speeds. Otherwise, many types of step motor and driver have to be produced in order to satisfy customer's need for different step angles.After study many kinds of driver technology, a microstepping driver for three-phase hybrid stepper motor has been designed. The driver adopts sine wave current subdividing and current tracking PWM technology. Sine wave current subdividing technology not only overcomes the disadvantages of motor's vibration and noise at low speeds but also reduces probability of resonance. Current tracking PWM technology can maintain constant torque within wide speed range. This driver has 16 kinds of microstepping modes and four kinds of output phase current that can meet the need of different customer and motor. The power stage of this driver uses IGBT intelligent power module that provides high reliability.Experiments indicate this microstepping driver reduce vibration and noise of step motor. It has small size, low cost and high reliability. Some enterprises used this type of driver successfully in NC-system of bag-making machine.
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