NEMA 17 – The High Toque Stepper Motor Working Principle

Even the most basic electronics typically include an electric motor. As a result, it is crucial, particularly in systems that incorporate rotational motion. However, not all engines can be beneficial in circumstances when accuracy is required. The NEMA 17 stepper motors are useful in this situation. We’re going to give you all the important information about how this component works.

Fig.1. Dis-assembled electric step motor parts

NEMA 17 Stepper motor has a 1.8° step angle. There are 200 steps or revolutions per angle. Each phase of the motor type can draw a voltage of 12V when it is in operation. As a result, the current can maintain a holding torque of 3.2 kg-cm. Keep in mind that the motor type has six wires that are color-coded as well. Additionally, a bare lead is present on each cable. To provide control by unipolar and bipolar stepper motor drivers, cables are therefore essential. 

A stepper motor, also known as a step motor or stepping motor, is a brushless DC electric motor that separates a whole rotation into many equal steps. Without a position sensor to provide input, the motor’s position can be told to move and hold at one of these phases as long as it is scaled correctly for the application in terms of torque and speed (an open-loop controller). Switched reluctance motors are large stepping motors with fewer poles.

Mechanism of the Stepper Motor:

When DC voltage is applied to the terminals of brushed DC motors, the motors continue to spin. Stepper motors are well known for their ability to transform input pulse trains (usually composed of square waves) into accurate increments in rotational position. Each pulse rotates the shaft through a fixed angle.

Fig.2. Stepper Motor

A stepper motor consists of several “toothed” electromagnets arranged as a stator revolving around a central iron rotor. One electromagnet is powered to magnetically attract the gear teeth and turn the motor shaft. When lined up with the first electromagnet, the gear teeth are slightly offset from the next electromagnet. By turning off one electromagnet and turning on the next, the gear spins a little to line up with the next electromagnet. The process is then repeated. In a stepper motor, a full rotation is made up of a precise number of precise steps, each called a “step”.

Pin Description of the Motor:

Fig.3. Pin description of the NEMA17

Six wires or coils each with a specific function are part of the stepper controller. Two primary sections of the wires are wound. On the coil’s first winding, the black, yellow, and green wires come first. The second portion of the winding is then formed by the Red, White, and blue wires. The motor’s pin arrangement is shown here in the following manner:

No.	Pin Name	Wire Color
1	Coil 1	Black
2	Coil 2	Yellow
3	Coil 3	Green
4	Coil 4	Red
5	Coil 5	White
6	Coil 6	Blue

How to use the NEMA17 stepper motor:

The operation of NEMA 17 stepper motors is rather simple. Look at the coil schematic below first. It is essential to understand how the stepper motor will revolve around the wiring stages.

Fig.4. NEMA17 stepper motor coil diagram

Keep in mind that NEMA 17 stepper motors frequently require large currents. Therefore, using a driver IC like the A4988 is required. Additionally, the engine includes two split windings and six wires. The Centre winding taps are connected to the positive supply while in use. Over a drive circuit, every winding’s two ends are alternately grounded.

Applications:

3D printer: A stepper motor is almost present in lists of common 3D printer parts. This is because a stepper motor is a highly accurate and economical means to make extremely exact rotations and actions while a 3D printer is attempting to convert data from digital scans into actual 3D objects.

Computer Numerical Control (CNC): The majority of CNC machinery can be powered by stepper motors instead of servo motors. Numerous manufacturing processes use CNC applications, in which machine tools are operated and moved physically by pre-programed computer software in manufacturing and fabrication environments.

Cameras: For use in camera and video surveillance positioning systems, stepper motors also offer several other desirable characteristics, such as full torque at a standstill, extremely quick and accurate response times for all movement inputs, consistent repeatability of predetermined movements, and simple open-loop controls defined by fixed step sizes.

Conclusion: 

Stepper motors have a sophisticated appearance as we just mentioned, they work on a simple premise. Stepper motors allow users to boost the precision and efficiency of programmed movements across many applications and sectors. They are very versatile, dependable, affordable, and accurate. In the much larger category of automation and control gear, they thereby represent a significant and commonly utilized subgroup.

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