Difference Between Stepper Motor and Servo Motor

Stepper motors and servo motors are two important technologies in the automation and precision control industry. While they both play an important role in industrial applications, they have distinct characteristics and advantages. In the article below, join RX Tradex to learn about the difference between stepper motors and servo motors.

1. Basic Differences Between Stepper Motor and Servo Motor

Stepper motors typically use non-contact sliding technology, with the number of pole points ranging from 50 to 100. In contrast, a typical servo motor has only 4 to 12 pole points.

The obvious difference between stepper motors and servo motors is in the coding and position control method:

• Stepper motors do not require coding because they can move precisely to the positions of nearly 100 pole points in the motor. They work by controlling each step through the supply of electrical pulses to the coils.
• Servo motors, although only have a smaller number of pole points, need to be coded to accurately determine the location of each pole point. They work by reading data from motor encoder signals and adjusting the current to achieve the required position.

Plus:

• In multi-pulse mode, the stepper motor rotates more smoothly (without jerking), due to the absence of brushes and the rotor is made of permanent magnets, which increases sustainability over time.
• The servo motor can be a DC or AC motor, equipped with an encoder to increase the accuracy in position control. Combined with encoder, DC and AC motors become DC servo motors and AC servos respectively.

2. Advantages and disadvantages between servo motors and stepper motors

Servo motor thanks to the feedback of the encoder, conditional closed-loop control, so it has higher accuracy. Thanks to this mechanism, the servo motor is capable of controlling the position with high precision even in the event of force slippage (motor loss of step), ensuring the required precise positioning.

In contrast to stepper motors, when there is a force slippage, stepper motors often give incorrect position results due to loss of step.

In particular, servo drivers require higher power and have weaker torque than drivers for stepper motors. DC servo motors are generally less durable due to the use of brushes and the need for periodic maintenance.

On the other hand, stepper motors can operate for a long time and require little maintenance due to the absence of brushes, which are compact in size but provide great torque.

These characteristics highlight the differences between servo motors and stepper motors, which are suitable for each specific application and requirement in modern industrial and automation systems.

3. Notable points between servo motor and step motor

In today’s practice, there are many stepper motors equipped with a rear encoder to take full advantage of the advantages of stepper motors and closed-loop control capabilities such as servo motors.

For the programming and control of the stepper motor, the positioning process is usually based on the number of steps (each step corresponds to a certain rotation angle). When applying an electric pulse to the coils, the motor moves step by step and from there we can deduce the specific position.

In contrast, with servo motors, the control reaches the desired position using a more complex mechanism. The servo motor is driven based on the number of pulses from the encoder. When the motor is given a pulse sequence from the encoder, the system counts and monitors the number of pulses. When a certain number of pulses are counted from the encoder, the servo motor will stop at the desired position.

This difference in programming and control clearly reflects the superior characteristics and precision of each type of motor in modern industrial and automation applications.

4. Conclusion

Through the above article, RX Tradex has reviewed the basic differences, advantages and disadvantages, and notable points between stepper motors and servo motors in the industry. Hopefully, you have more useful information to apply to the practice of production and automation of your industrial processes. In addition, if you are interested in the latest technologies and market trends, you can participate in NEPCON 2024 – the only exhibition in Vietnam on SMT, Inspection Technology, Equipment and Supporting Industry for Electronics Manufacturing organized by RX Tradex Vietnam. In addition, this year, RX Tradex also organized leading exhibitions in the region such as Vietnam Manufacturing Expo, METALEX Vietnam,… Register right here.