A stepper motor is an electromechanical device that converts electrical pulses into precise mechanical motion. It is designed to move in discrete steps, hence the name "stepper" motor. Unlike conventional motors that rotate continuously, stepper motors rotate incrementally, typically in steps of 1.8 degrees (for a motor with 200 steps per revolution).
The basic construction of a stepper motor consists of multiple toothed electromagnets arranged around a central rotor. The rotor is typically made up of a permanent magnet or a soft magnetic material. The number of teeth on the rotor is usually a multiple of the number of electromagnets surrounding it.
Stepper motors require a specialized driver circuit to control their motion. This driver circuit delivers precise sequences of electrical pulses to the motor windings, which in turn produce the rotational movement.
The most common types of stepper motors are bipolar and unipolar motors:
1. Bipolar Stepper Motor: A bipolar stepper motor has two windings or phases, and each phase can be controlled independently. The windings have a center tap, and the motor can have either four or eight leads. Bipolar motors provide more torque compared to unipolar motors but require more complex driver circuits.
2. Unipolar Stepper Motor: A unipolar stepper motor has multiple windings with a center tap for each phase. The windings are typically energized in a specific sequence to create the steps. Unipolar motors are easier to control but generally provide less torque than bipolar motors.
To rotate the stepper motor, the driver circuit applies voltage or current to the motor windings in a specific sequence. The most common sequence is known as "wave drive" or "one-phase on." In this mode, the driver energizes one phase at a time and steps through the phases in a cyclic manner to rotate the motor.
More advanced driving techniques, such as "full step," "half-step," or "microstepping," can be used to achieve smoother motion or finer positioning. These techniques involve different energization patterns for the motor windings, which divide a full step into smaller increments.
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