The Servo motor vs. Stepper motors debate has been going on for years. When buying a motor, people often wonder which motor is preferable, but the answer is that it depends on the application and cost. Using the proper motor with high-quality parts and performing regular maintenance keeps your facility running smoothly and protects endpoint equipment from wear and power spikes.The selection of a correct motor for the application involves several parameters like torque, speed.
This article will teach you the main difference between the Servo and Stepper motors, and how to choose the right one.
WHAT IS A STEPPER MOTOR?
A stepper motor is an electromechanical device that converts electrical power into mechanical power. It’s also a brushless, synchronous electric motor with the ability to divide a full rotation into a significant number of stages. As long as the motor is properly sized for the application, the position of the motor can be precisely regulated without the use of any feedback device.
The step movement becomes continuous rotation as the frequency of the digital pulses increases, with the speed of rotation being directly proportional to the frequency of the pulses. Because of its low cost, great reliability, high torque at low speeds, and a simple, sturdy architecture that can function in practically any environment, step motors are utilized every day in both industrial and commercial applications.Some of the features of stepper motor is given below:
- small step angle
- high positioning accuracy
- high torque to inertia ratio
- stepping rate and accuracy
• Simple design/control
• No feedback required
• Excellent low speed torque
• Excellent low speed smoothness
• Lower overall system cost
• Torque decreases as speed increases
• Constant current regardless of requirements
• Cannot react to changes is load
WHAT IS A SERVO MOTOR?
Servo motor is a rotary actuator or linear actuator Servo motors are motors capable of providing very precise angular or linear control. It comprises of a suitable motor coupled to a sensor for position feedback.
A servo motor system’s feedback detects the difference between the actual and desired speed or position so that the controller may rectify any deviation from the target position. The two primary types of servo motors are positional rotation and continuous rotation.Some of the features of servo motor are:
- Inertia of the servo motor should be less for precision and accuracy
- Offers a fast response which can be obtained by keeping a high torque to weight ratio.
- The torque-speed characteristics should be linear
- Four quadrant operation is desirable by using further converters.
- Stable operation
- Robust nature.
• Closed loop control
• Higher torque at higher speed
• Lower motor heating
• Better choice for variable load systems
• More complex control – tuning required
• Position feedback required
• Higher overall system cost
WHAT IS THE DIFFERENCE BETWEEN THE STEPPER MOTOR & SERVO MOTOR?
Here we are going to discuss the major differences between the stepper motor and servo motor in detail.
- Number of Poles
A magnetic pole pair is a set of north and south magnets that work together to rotate a motor. The motor can be two-pole, four-pole, eight-pole, and so on. A stepper motor has a lot of poles, usually between 50 and 100.
The pole count of a servo motor is normally 4-8. Consider the poles to be your teeth. The more teeth you have, the better able you are to chew things effectively.
The number of poles affects the magnetic fields and current inside the motor. That means, the more poles a motor has, the better it can control its spinning.Due to large number of poles in the stepper motor, it is able to move in more counts and stepwise; that too in small steps The greater the number of steps in a single revolution, the more accurate it will be.
As a result, the stepper motor may be utilised in open loop control with complete trust, as it is precisely controlled by its own step motions.For proper control, a servo motor will require closed loop control with encoder feedback.
Stepper motors provide a high amount of torque at low speeds, due to the high number of poles. This isn’t feasible in servo motors because they produce less torque than conventional motors.
Stepper motors, on the other hand, offer relatively low torque at higher speeds and typically lose a lot of torque. The fundamental advantage of servo motors at greater speeds is that they provide more torque.
- Vibration level and Heat
Stepper motors produce very high levels of vibrations and resonance. They also dissipate a large amount of heat as compared to servo motors.
Stepper motors are less expensive than servo motors. Moreover, servo motors require an encoder and gearbox for more precise control, the cost of these components makes this motor more expensive.
However, if you ignore the cost consideration, you will find that using closed-loop control gives you more control and more features in operating the system than using stepper motors.
The speed of the servo motor is higher than the stepper motor. They provide greater RPM as compared to stepper motors.
Servo motors tend to pulsate or vibrate in standstill position; which does not happen in stepper motors.
So, if you need a motor to hold a load stable as a rock and not cause any havoc in the system, a stepper motor is an excellent choice.
There are some general differences between servo and stepper motors. Choosing the proper motor is entirely dependent on the application and the designer’s expertise. Hope all of you find this article informative. For more queries, contact our online store-MATHA ELECTRONICS