What Is A Stepper Motor?

A stepper motor is a very unique type of brushless DC motor because of the internal rotation of the motor. A direct current is sent in pulses to energize sets of stator windings in turn, and movement is created by intentionally designing the motor to have a different number of stator teeth in comparison to the number of rotor teeth. In doing so, only some sets can be aligned at any given time. By de-energizing the set of stator teeth that are aligned and then energizing those that are adjacent, the rotor teeth will “step” to the next position, making a rotation based on the movement that requires the smallest step. The geometry of the teeth will determine the degree of the movement from one position to the next; this angel is expressed as a “step size.”

 

 

Additionally, half-stepping can be achieved by energizing two coils at one time (to create a half step in between the two) before completely de-energizing the previous coil. In this way, a stepper motor with a 1.8-degree step between rotor teeth could also rotate at step angles of 0.9 degrees, offering even more precision and control.

Going one step further, micro-stepping can be accomplished by changing the intensity of the charge sent to the two coils at the same time. This will create an unequal pull between them and add additional steps between alignment with the two teeth. (However, this does require an even more complex motor driver in comparison with half-stepping, the torque is smaller per step, and the possibility of missing steps increases.)

Because they do not continuously rotate, stepper motors do not receive a horsepower rating, and the frequency of the pulses directly controls the speed of the motor. They cannot run at high speeds nor are they high power devices, but they are incredibly precise and have a high holding torque.

They are ideal for operations at moderate speeds where motion accuracy is required, because their special movement allows for control over the angular position of the rotor without a closed feedback loop (no sensor is required to determine the motor position). The simple, open, and accurate open-loop system does not require feedback for accurate movements when used for applications such as assembly-line or packing robots.

 

Micro and Small Stepper Motors

As they are ideal for low power situations where simple but precise movements are required, this is also what makes them so ideal for small applications. They offer good torque for the size and weight and often have quite a long lifespan so they will likely last the lifetime of your small toy or electronic device.

Micro or small stepper motors may only be a few millimeters in diameter and are used in small electronics such as phones and cameras and in toys like RC cars or drones. They are also great for 3D printers, robotics, and conveyors.

Advantages and Disadvantages of Stepper Motors

Stepper motors are relatively inexpensive and are rather durable, so they also have long lifespans. Because of both of these factors, they have a low initial investment and also do not hit you with the cost of frequent replacements down the line nor require the hassle of taking apart your assembly to repair or replace the motor. The motor control is also pretty simple, it may not require a sensor to determine the motor position or require complex calculations and tuning in order to work correctly. For low to moderate power requirements and low weight-bearing jobs, stepper motors are a clear choice.

However, there are disadvantages to this kind of motor as well. A stepper motor might become noisy and miss-steps if it is rotating too quickly, so if you require high speeds and high torque, it might not be the right motor for the job. Overall, they have a low torque to inertia ratio as well as low power density.

Do You Have A Project That Calls For A Micro Stepper Motor?

If you are considering a small or micro stepper motor for your own personal project, you have come to the right place. Our team provides a wide variety of conventional and hybrid stepper motors with modifications available to ensure that no matter what you’re working on, we can help you choose (or design) the perfect motor for your project. Please don’t hesitate to contact us with any questions you have about stepper motors or about choosing the best motor to meet the needs of your job.

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