Guide to NEMA 17 Stepper Motors: How They Work, Advantages and Disadvantages, How to Use Them, and Their Application Scenarios
2024-01-19 14073

In today's highly automated technological field, the NEMA 17 stepper motor, with its precise control capability and robust adaptability, has become an essential component of precision control systems. This article aims to delve into the construction, characteristics, and control strategies of the NEMA 17 stepper motor in advanced applications. From its unique step angle characteristics and efficient energy conversion capabilities to its performance in various application scenarios, we will analyze the technical details and application advantages of this motor in detail. Particularly in areas like 3D printers, CNC machines, and robotic technologies, the NEMA 17 stepper motor demonstrates its irreplaceable importance with its high positioning accuracy and strong holding torque. We will also explore its coil layout, current control, and driver configuration, which collectively determine the motor's performance and efficiency.

stepper motor

NEMA 17 stepper motors are the cornerstone of precision control systems and excel at providing detailed angle management. Its notable feature is the 1.8° step angle, which helps the motor shaft rotate accurately with each step. A complete 360° rotation requires 200 steps. This complex stepping has proven to help improve positioning accuracy, making the motor an excellent choice for 3D printers, CNC machines and robots where accuracy is critical.

NEMA 17 motors operate on standard 12V and are capable of expertly managing up to 1.2A per phase. This capability plays a key role in ensuring maximum holding torque. With a peak holding torque of up to 3.2 kg-cm, the motor is ideally suited to handle the large loads found in automation equipment.

How NEMA 17 Works

The wiring configuration is an aspect worth noting, NEMA 17 motors include six color-coded wires with exposed lead ends. The functions of these wires vary depending on whether they are in a unipolar or bipolar stepper motor driver.

The motor's windings are divided into two groups: the first contains black, yellow, and green conductors, and the second contains red, white, and blue conductors. This special arrangement is critical for efficient management of current and torque. Within these windings, the direction and strength of the current flow complexly influence the resulting magnetic field and thus torque and speed. Careful management of these windings is critical to ensuring stable, efficient operation of the motor under varying load conditions.

Furthermore, proper wiring configuration goes beyond mere performance considerations; it significantly affects the life of the motor. Improper wiring can cause problems such as motor overheating or reduced torque, while correct settings can maximize efficiency and output. Therefore, in the design and implementation of stepper motor control systems, attention must be paid to these complex issues.

Characteristics

• Efficiently converts current into torque.
• High durability and accuracy.
• Suitable for various devices like Makerbot, MBot, etc.
• Moderately sized for easy integration.

Specifications

• Step angle of 1.8 degrees.
• Weight of 350 grams.
• Rated current of 1.2A per winding.
• Output shaft diameter of 5mm.
• Control dimensions of 42.3mm×48mm (excluding shaft).
• 4-wire, 8-inch leads.
• Holding torque of 3.2 kg-cm.
• Rated voltage of 4V, operating voltage of 12V DC.
• The inductance of 2.8 mH per winding.
• Lead length of 30 cm.
• Operating temperature range of -10 to 40°C.
• Holding torque of 22.2 oz-in.

Structure of stepper motors

Advantages of stepper motors

The angle of rotation of the rotor is determined by the number of pulses applied. The stepper motor rotates unevenly, but the steps have a certain value. So to turn the axis to the desired position we simply apply a known number of pulses.

The position depends on the input pulse, enabling feedback-free positioning. One step, one impulse. With the number of pulses provided, the engine enters this position.

The engine delivers full torque in stop mode. This is good because the powered motor doesn't need a brake to hold the position of the shaft, you can brake it with the help of the driver.

Precise positioning and repeatability. A good stepper motor has an accuracy of 3% to 5% of the pitch value. This error does not accumulate from one step to the next because the number of steps per engine revolution is constant, which always results in a 360-degree turn.

High reliability. The high reliability of the motor is due to the absence of brushes. The service life is determined by the service life of the bearing.

Possibility of obtaining low RPM. To obtain a lower motor speed, it is enough to slow down the pulse rate, then the motor will go slower and the speed will be small.

High torque at low speed. High torque at low speeds eliminates the need for a gearbox, simplifying equipment design.

A considerable speed range can be covered. The speed of the motor is directly proportional to the frequency of the input pulses, by delivering them faster or slower we also affect the rotational speed.

Disadvantages of stepper motors

Stepper motors are characterized by the phenomenon of resonance. Stepper motors have an inherent resonant frequency. This is because the rotor will oscillate for some time before locking into its final position after supplying current to the windings, and the greater the inertia of the rotor, the stronger the oscillation. Resonance can lead to increased noise, vibration, and reduced engine torque. One way to defeat resonance is to increase pitch divisions. Small movements in micro-stepping do not require long periods of acceleration and rotor fixation, stopping quickly between steps and increasing the walking frequency above the resonant frequency.

Since there is no feedback from the operation, position control may be lost. If the force on the shaft exceeds what the motor can produce, it will start skipping steps. Since there is no feedback from the motor, the controller has no way of knowing that, even if the motor starts spinning again, it is starting from the wrong operating position. To compensate for this shortcoming, you can use a servo stepper motor or increase the torque on the shaft by increasing the voltage, tuning the drive to a higher current, or replacing the motor with a more powerful one.

Energy is consumed regardless of load. The stepper motor in the neutral position locks at full torque. He also walks with plenty of momentum. Therefore, it continues to consume power without much dependence on the load on the shaft. We can reduce the overall energy consumption of the motor by using a driver to reduce the current provided in hold mode.v

NEMA 17 Stepper Motor Usage and Control Strategies

NEMA 17 stepper motor applications

Conclusion

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