The Basic Knowledge and Application of Stepper Motor

What is a stepper motor? Stepper motor is an actuator transforming electric pulse into angular displacement. Popularly, when receiving a pulse signal, the stepper motor will rotate a fixed angle (namely"stepping angle") according to the direction set for the stepper motor. The angular displacement volume can be controlled by controlling the pulse number to achieve the purpose of positioning accurately. In the meantime, the rotational velocity and acceleration of motor can be controlled by controlling the pulse frequency to achieve the purpose of speed control.
The stepper motor is an electromagnetic device that converts digital pulses into mechanical shaft rotation. Advantages of step motors are low cost, high reliability, high torque at low speeds and a simple, rugged construction that operates in almost any environment.

The most widely used motors in motion controls are stepper motors. Stepper motors are relatively inexpensive compared to brushless dc motors. They are able to be very accurately controlled for the most precise positioning applications without any feedback devices like encoders or hall sensors. Stepper motors can be classified by different ways of wiring (unipolar or bipolar), various step angles (1.8 degree, 0.9 degree or micro stepping) and the numerous NEMA frame sizes. NEMA frame sizes refer to the motor mounting pattern.

It was brought up by National Electrical Manufacturers Association to indicate the physical characteristics of the stepper motor. It has nothing to do with the motor’s electrical characteristics such as horsepower or voltage. For example, a NEMA 17 stepper motor has a 1.7 inch square flange with 4 mounting holes, one at each corner of the square. Likewise, a NEMA 23 stepper motor has a 2.3 inch square mounting flange with an individual hole at each corner. Currently, the most commonly used stepper motors are NEMA 17 NEMA 23 and NEMA 34. But in some specific applications, NEMA 8 NEMA 11 NEMA 14 and NEMA 42 stepper motors are also used.

Stepper motor is divided into three types: permanent magnet stepper motor (PM), variable reluctance stepper motor (VR) and hybrid stepper motor (HB).
The operation of this motor works on the principle that unlike poles attract each other and like poles repel each other. When the stator windings are excited with a DC supply, it produces magnetic flux and establishes the North and South poles.


Choosing a Stepper Motor and the controller
Choose the right stepper motor for your application