24-09-2013, 04:22 PM
Stepper motot
Stepper motot.pptx (Size: 56.07 KB / Downloads: 34)
INTRODUCTION
A stepper motor is a brushless, synchronous electric motor that converts digital pulses into mechanical shaft rotation. Every revolution of the stepper motor is divided into a discrete number of steps, in many cases 200 steps, and the motor must be sent a separate pulse for each step. The stepper motor can only take one step at a time and each step is the same size. Since each pulse causes the motor to rotate a precise angle, typically 1.8°, the motor's position can be controlled without any feedback mechanism. As the digital pulses increase in frequency, the step movement changes into continuous rotation, with the speed of rotation directly proportional to the frequency of the pulses. Step motors are used every day in both industrial and commercial applications because of their low cost, high reliability, high torque at low speeds and a simple, rugged construction that operates in almost any environment.
Stepper Motor Advantages
The rotation angle of the motor is proportional to the input pulse.
The motor has full torque at standstill (if the windings are energized).
Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 to 5% of a step and this error is non-cumulative from one step to the next.
Excellent response to starting/stopping/reversing.
Very reliable since there are no contact brushes in the motor. Therefore the life of the step motor is simply dependant on the life of the bearing.
The stepper motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.
It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.
A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.