BASIC STEPPING-MOTOR CONTROL CIRCUITS (Electric Motors)

10.8
This section deals with the basic final-stage drive circuitry for stepping motors. This circuitry is centered on a single issue, switching the current in each motor winding on and off and controlling its direction. The circuitry discussed in this section is connected directly to the motor windings and the motor power supply, and this circuitry is controlled by a digital system that determines when the switches are turned on or
off.
This section covers all types of motors, from the elementary circuitry needed to control a variable-reluctance motor to the H-bridge circuitry needed to control a bipolar permanent magnet (PM) motor. Each class of drive circuit is illustrated with practical examples, but these examples are not intended as an exhaustive catalog of the commercially available control circuits, nor is the information given here intended to substitute for the information found in the manufacturer’s component data sheets for the parts mentioned.
This section covers only the most elementary control circuitry for each class of motor. All of these circuits assume that the motor power supply provides a drive voltage no greater than the motor’s rated voltage, and this significantly limits motor performance. Section 10.9, on current-limited drive circuitry, covers practical high-performance drive circuits.