STEP MOTOR Yisheng Zhang

Overview What is a step motor? How to control it? Why to use it? Where to use it? How to select it? Where to get it?

What is a step motor? An electromagnetic device – Convert digital pulses into mechanical shaft rotation – Has no brushes Precision – Determined primarily by the number of steps per revolution

How to control it? User interface: host computer, PLC, or dumb terminal Indexer (or Controller): a microprocessor capable of generating step pulses and direction signals Driver (or Amplifier): translates the indexer command signals into appropriate phase currents to energize the motor windings Rotation angle has a direct relation to the number of input pulses Speed is related to the frequency of the pulses

Why & where to use it? Advantages – Open-loop control, high reliability, low cost Disadvantages – Can’t tell slip using open-loop control Applications – Printers (paper feed, print wheel) – Disk drives – Clocks and watches – Factory automation – Many other applications

How to select & where to get it? Considering load characteristics, performance requirements, and mechanical design including coupling techniques A long list of parameters to be considered are included in the report Availability – From old printers – Lin Engineering Step Motor Specialists – Anaheim Automation