Industrial Motors are used to convert electrical energy to mechanical energy. They are neither precision speed nor precision positioning devices.For an automated systems, precise speed and precise positioning are required.To fulfill these limitations stepper motors are used.
The Stepper Motor becomes very popular because it can be controlled directly by computers, microprocessors and programmable controllers.
The only moving part in a stepper motor is its rotor. The rotor has no windings, commutator or brushes. Because of these feature the motor is quite robust and reliable.
The angle through which the motor shaft rotates for each command pulse is called the step angle.
The relationship between steps per revolution and step angle is given by the following formula:-
Step angle = 360° / [No. of steps per revolution]
Smaller the step angle, greater the number of steps per revolution and higher the resolution or accuracy of positioning obtained.
Some stepper motor operates upto 20,000 steps per second. Still it remain fully in synchronism with the command pulses.
When the pulse rate is high, the shaft rotation looks like continuous. Such an operation of stepper motor at high-speed is called ‘slewing’.
1. Variable Reluctance Stepper Motor.
2. Permanent Magnet Stepper Motor.
3. Hybrid Stepper Motor.
1.Stepper Motors are used in a variety of automation applications in which a relatively small amount of torque is needed.
2.Typical applications include rotary table control, wire-harness assembly, laser or pen positioning, and office peripheral equipment control.
3.Stepper motors can be used for precise positioning, without the need for a complicated position indicating feedback system.