Table of Contents
Introduction to Stepper Motors
Stepper Motor and Controller
Stepper Motor Concepts
- Look at the open Mercury motor. The two "phases", each of which consists of several coils, always have opposite currents.
- Anaheim Automation
has a nice selection of stepper motors. Note that some motors have integral gear boxes. Gears usually exhibit backlash.
Empire Magnetics makes vacuum rated motors,
cryogenic motors and
waterproof motors. With suitable gear
ratios, surprisingly small stepper, AC, DC or hydraulic motors can drive impressive
slew drives.
Warning! Never, ever, ever disconnect the motor from the controller when the power is on.
Remember Faraday's law. If you suddenly disconnect the current through a coil, the energy stored in the coil
will be dissipated through an electrical discharge. A large value in dI/dt will create a large potential difference
across the two sides of the coil, and this potential will damage the controller.- How much torque is required to rotate the shaft of your motor when disconnected from the driver?
When the coils are shorted with a wire or LED? When connected to the driver with the power on?
When stepping?
- There is a single bearings at each end of the shaft. Is there any play in this shaft when not energized or when energized?
Might there be some oscillation of the shaft when a step is taken?
- Steppers are prone to resonance oscillations at particular step frequencies, and they begin to miss a step
occasionally when the step rate is too high.
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