Stepping Motors Fundamentals
Stepping motors fill a unique niche in the motor control world. These motors
are commonly used in measurement and control applications. Sample applications
include ink jet printers, CNC machines and volumetric pumps. Several features
common to all stepper motors make them ideally suited for these types of applications.
These features are as follows:
- Brushless – Stepper motors are brushless. The commutator and brushes
of conventional motors are some of the most failure-prone components, and
they create electrical arcs that are undesirable or dangerous in some environments.
- Load Independent – Stepper motors will turn at a set speed regardless
of load as long as the load does not exceed the torque rating for the motor.
- 3. Open Loop Positioning – Stepper motors move in quantified increments
or steps. As long as the motor runs within its torque specification, the position
of the shaft is known at all times without the need for a feedback mechanism.
- 4. Holding Torque – Stepper motors are able to hold the shaft stationary.
- 5. Excellent response to start-up, stopping and reverse.
The following sections discuss the most common types of stepper motors, what
circuitry is needed to drive these motors, and how to control stepping motors
with a microcontroller.
AN907, Stepping Motors, Stepper Motors, Unipolar, Bipolar, Bifilar, Hybrid