Ⅰ Stepper motor definition

A stepper motor is a brushless synchronous DC motor that, unlike many other common types of electric motors, does not simply rotate for an arbitrary number of spins before the DC voltage is switched off.

stepper motor

Stepper motors, on the other hand, are a type of digital input-output device that allows for precise starting and stopping. They're designed so that the current passing through it hits a series of phased coils that can be turned on and off in rapid succession. This allows the motor to turn a fraction of a rotation at a time, and we refer to these individual predetermined phases as "steps."

A stepper motor divides a single full rotation into a series of much smaller (but essentially equal) part-rotations. These can be used to instruct the stepper motor to move through specific degrees or angles of rotation for practical purposes. As a result, a stepper motor can be used to transfer minutely precise movements to mechanical parts that require extreme precision.

Stepper motors are usually digitally controlled and play an important role in an open-loop motion-control positioning system. They're most commonly used in holding and positioning applications, where their ability to assert much more clearly defined rotational positions, speeds, and torques make them ideal for tasks that require extremely precise movement control.

Ⅱ Stepper motor working principle

A brushed DC motor works by applying a voltage to terminals, which allows a wire coil to spin at a high speed within a fixed magnet housing (the stator).

stepper motor internal structure

The spinning wire coil (the rotor) essentially becomes an electromagnet in this configuration and spins rapidly at the motor's core based on the well-known magnetic attraction and repulsion theory. Brushes (electrical contacts) and a commutator (a rotary electrical switch) work together to easily adjust the direction of the current flowing through the wire coil. As long as the assembly is supplied with enough voltage, the rotor coil spins in a continuous unidirectional fashion.

The fact that this sort of motor spins indefinitely and for an infinite number of rotations before power is turned off is a possible drawback. This makes it difficult to control the motor's exact stopping point, making it unsuitable for applications that need greater precision. Manually regulating the flow of power to the motor will not provide the start-stop precision necessary for performing minutely precise movements.

The configuration for a stepper motor is very different. Stepper motors are constructed with a fixed wire housing (the stator in this case) arranged around a series of "toothed" electromagnets spinning at the core, rather than a wire coil rotor spinning within a fixed housing of magnets. A pulsing electrical current operated by a stepper motor driver is translated into precise one-step movements of this gear-like toothed part around a central shaft by the stepper motor.

The rotor is pushed by one exact and set increment of a full turn by each of these stepper motor pulses. The rotary part can complete full or partial turns as needed as the current changes between the wire coils arranged in sequence around the outside of the motor, or it can be made to stop very suddenly at any of the steps around its rotation.

The real advantage of a stepper motor over a standard DC brushed motor is that it can easily locate itself to a known and repeatable location or interval, and then maintain that position for as long as it is required. This makes them suitable for high-precision applications like robotics and printing.

Ⅲ Stepper motor types

There are several different types of stepper motors available, and learning what each one does will help you determine which one is better for your application.

1.Bipolar stepper motor

A bipolar stepper motor has an onboard driver that reverses the current flow through the phases using an H bridge circuit. All of the coils can be put to work turning the motor by energizing the phases while reversing the polarity.

In practice, this ensures that a bipolar stepper motor's coil windings are more used than a typical unipolar stepper motor (which only uses half of the wire coils at any given time), allowing bipolar stepper motors more effective and efficient to work. While bipolar stepper motors are theoretically more difficult to operate, they typically come with an inbuilt driver chip that takes care of the majority of the necessary instructions and behaviors.

Since unipolar stepper motors don't need the current flow to be changed in order to conduct stepping functions, they're generally more costly at first. This makes their internal circuitry much smoother and quicker to manufacture.

2.Hybrid stepper motor

Hybrid stepper motors have much more accuracy due to half-stepping and micro-stepping techniques. Microstepping involves programming a driver to give an alternating sine/cosine waveform to the coils in order to maximize the set number of steps in a motor. Stepper motors will also be set up to work faster and more reliably than in a regular configuration if this is achieved.

Poles or teeth are normally offset on two separate cups along the edge of the magnet rotor in hybrid stepper motors. This makes for more accurate control of phases and rotations, as well as quieter running, better torque-to-size ratios, and quicker performance speeds than typical stepper motors.

Ⅳ Stepper motor applications

Stepper motors are used in a number of industries and disciplines, with some of the most famous examples being:

• Computing

• Robotics

• Cameras

• Scanners and printers, including 3D printers

• Automation of systems and packaging equipment

• Valve pilot stage placement for fluid control systems

• Equipment for accurate placement

1.Stepper motors for 3D printers

A stepper motor of some sort is almost always included in standard 3D printer parts lists. This is because using a stepper motor in a 3D printer helps you to perform very precisely, realistic movements and rotations while the printer is trying to convert details from computer scans into actual 3D objects.

Stepper motors and drivers in 3D printers allow for precisely controlled movement along the X, Y, and Z axes, either independently or simultaneously, allowing for incredibly accurate movement and positioning without the use of encoders or any external software or sensors.

Multiple stepper motors are usually used in both the construction platforms and the filament extruders of 3D printers, where they are used to help pull in filament and monitor the continuous, even supply of material to the system over the length of a print run.

2.Stepper motors for CNC

For powering most forms of CNC equipment, stepper motors are an alternative to servo motors. CNC systems include a wide variety of industrial processes in which computer software is used to monitor the operation and physical movement of machine tools in factory and fabrication environments.

Although stepper motors are frequently thought of as a less costly alternative to servo motors in CNC applications, this is an oversimplification dependent on the experience of older technology that isn't really true today. For the same power, stepper motors are usually less costly than servo motors, but modern models are just as flexible. As a result, stepper motors became becoming more readily available and used in a broader variety of devices and systems, ranging from machine tools to personal computers and cars.

CNC stepper motors have another major benefit over servo motors: they do not need an encoder. Servo motors are generally more difficult to grasp and control than stepper motors, and this difficulty is compounded by the fact that they have an encoder, which is more vulnerable to failure than any other parts of the otherwise stable servo motor. Since stepper motors do not need an encoder, they are potentially more efficient than servos.

Furthermore, unlike servo motors, stepper motors are brushless, which means they won't need to be replaced on a daily basis as long as their bearings are in good working order.

3.Stepper motors for Raspberry Pi

Stepper motors are a common peripheral for connecting to Raspberry Pi single-board computing modules by home enthusiasts who want to learn the basics of computer programming.

Raspberry Pi starter kits are normally sold in a very simple setup, with the expectation that the individual user can install any additional components they choose to their system in the order in which they learn about them, expanding their ability set by learning to manage new components using programming languages like Python.

Learning to handle and monitor small, inexpensive stepper motors is often seen as a reasonable next step after learning to control LED on/off cycles and other basic switch or buzzer types among the Raspberry Pi user group. In effect, home hobbyists will begin to build a simple and programmable robot by attaching a couple of these stepper motors in series.

There is a range of suitable stepper motors for this use, beginning with very inexpensive 5V models that are simple to connect with headers on the Raspberry Pi motherboard.

4.Stepper motors for cameras

Stepper motors are commonly used in high-end camera technologies for a number of applications. They're used in the housings and exterior mechanics of surveillance cameras and remote monitoring devices, as well as to manage extreme precision internals like in-lens autofocus and aperture settings.

Stepper motors and motorized camera sliders, in particular, make for the very smooth running of camera-positioning rigs, ensuring that video recorded by surveillance cameras is free of potentially troublesome image distortion induced by the camera rotating across its field of view.

Stepper motors offer several further attractive functions, including full torque standstill, highly accurate and immediate response times for any motion input, consistent repeatability of pre-detailed motions, and simple open-loop controls defined by fixed step-sizes, for use in camera and video surveillance systems.

Ⅴ Summary

Stepper motors are an unbelievably versatile, reliable, economical, and precise way of controlling accurate motor movements that enables the user to increase programmed mobility dexterity and efficiency through a wide variety of applications and industries. This makes them an important and widely used subset in the much wider automation and control equipment category.

It is crucial to find out exactly which configurations are best suited to which kind of environments in the planning of purchase with so many stop-motion brands, sizes, torque rates, design styles, and intended applications for the worldwide market.