The Proliferated Use of Stepper Motors

Stepper motors are used to convert electrical power to mechanical power, hence they are electromechanical devices. They contain numerous coils ordered in groups known as ‘phases. The motor rotates step-by-step by energizing each phase sequentially. One can achieve speed control and precise positioning by computer-controlled stepping. These motors are available in various styles and sizes with varying electrical properties.

Characteristics of a stepper motor-

Speed control- One can acquire an excellent control on the rotational speed by precise increments in the movements. This has a lot of scope in robotics and automation processes.

Positioning- These motors are extensively used in applications like CNC, 3D printers, X-Y plotters, Camera platforms and much more due to their precise repeatable steps. Disk drives also make use of motors to position their read/write heads.

Low-speed torque- the regular DC motors do not posses much torque at low speeds, but a stepper motor has an exceptionally maximum torque even at low speeds. Hence, they are a perfect choice for applications that require low speed along with high precision.

Various operations of a stepper motor:

The general stepper motors have a different operation as compared to DC brush motors which are capable of rotating when a voltage is applied at their terminals. Whereas, these motors effectively contain multiple electromagnets in tooth-like arrangement around a gear-shaped central piece of iron. These electromagnets are excited by the use of an external control circuit like a microcontroller.

In order to turn the motor shaft, the initial electromagnet is supplied with power that makes the gear’s spikes magnetically attracted to the teeth of the electromagnet. Once the teeth of the gear are aligned to the electromagnet, they are put in a slight offset position from the next electromagnet. Hence, once the next electromagnet is supplied with power, the first one is turned OFF. The gear thus rotates up to some extent to align itself with the next electromagnet. This process is repeated thus forth. The single slight rotation of the electromagnet is known as a step. The cumulative integers of these steps result in a full rotation. In this manner, the stepper motor is turned precisely to its destination. It is important to note that these motors do not rotate continuously, instead they rotate in terms of a step.

On the stator, four coils are fixed maintaining a 90o angle between each coil. The motor’s connections are resolved by the interconnection between the coils. The coils are not coupled together in a stepper motor. The coils are energized in a cyclic order with coils having a 90o rotational step. This determines the direction of the shaft rotation. The working of a stepper motor is easily understood by operating the switch. The current consumption of a stepper motor is independent of the load unlike most of the DC motors. Due to this reason, they tend to draw a lot of currents that are often hot.