Controlling Stepper Motors

The most simple and cost effective way to control a stepper motor is to turn on the complete winding of the motor. A majority of stepper motors operate with four phases, this requires each phase to be turned individually. This is usually done by using a transistor switch that features an on and off button.

Also available off the shelf are chips that contain internal transistors which control the external mosfets (metal–oxide–semiconductor field-effect transistor). Once the full step is complete, the shaft of the motor will turn 1.8 degrees.

Stepper Motors

Stepper motors are also able to move in a half step, compared to the full step listed above. This refers as the motor only rotating one half of a step (.09) at a time, rather than a full step (1.8).

Like the full step transistor, mosfets can be used to inexpensively control the motor. When ran in half step the motor tends to run a bit smoother, and less resonance issues will occur.

In the 1980’s micro-stepping control were created for stepper motors, and quickly popularized by Compumotor. This type of drive technique is the most popular, however, it is also the most expensive compared to the half step or full step.

Since the creation of this type of stepper motor many companies have been able to develop micro-stepping motors at a more economical price. Many of the stepper motors on the market today operate by using the micro-stepping technique.

George

George Leger has a Masters in Electrical Engineering from Stanford University, worked in private industry pioneering surface-mount technology and in government research labs for twenty years, published several papers on surface-mount technology, co-authored papers published in national symposiums on accelerator technology, was past president of SMTA and an adjunct professor at the community college level, holds a patent, and is a certified microchip design partner, serving as a consultant to many companies developing electronic circuits.

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