Various motors are needed in many fields, including the well-known stepper motors and servo motors. However, for many users, they do not understand the main differences between these two types of motors, so they never know how to choose. So, what are the main differences between stepper motors and servo motors?
Servo motor
1、Working principle
These two motors are very different in principle, stepper motor is the electrical pulse signal into an angular displacement or linear displacement of the open-loop control element stepper motor parts, view the working principle of stepper motor.
And servo mainly relies on pulse to position, servo motor itself has the function of sending out pulses, so the servo motor every rotation of an angle, will send out the corresponding number of pulses, so that, and the servo motor to accept the pulse formed an echo, or closed loop, so that the system will be clear how many pulses sent and received how many pulses back, so that it can accurately control the rotation of the motor to achieve accurate positioning.
2、Control accuracy
The precision of stepper motor is generally achieved by the precise control of step angle, which has many different subdivision gears to achieve precise control.
The control accuracy of servo motor is guaranteed by the rotary encoder at the back end of the motor shaft, and the control accuracy of servo motor is generally higher than that of stepper motor.
3、Speed and overload capacity
Stepper motor in low-speed operation is prone to low-frequency vibration, so when the stepper motor in low-speed work, usually also need to use damping technology to overcome the phenomenon of low-frequency vibration, such as adding dampers on the motor or drive using subdivision technology, etc., while the servo motor is not the occurrence of this phenomenon, its closed-loop control characteristics determine its high-speed operation to maintain excellent performance. The moment-frequency characteristics of the two are different, and generally the rated speed of the servo motor is greater than that of the stepper motor.
The output torque of the stepper motor decreases as the speed increases, while the servo motor is a constant torque output, so the stepper motor generally has no overload capability, while the AC servo motor has a stronger overload capability.
4、Running performance
Stepper motors are generally open-loop control, in the case of too high a starting frequency or too large a load will be out of step or plugging phenomenon, so the use of the need to deal with speed issues or increase the encoder closed-loop control, see what is a closed-loop stepper motor. While servo motors use closed-loop control, easier to control, there is no loss of step phenomenon.
5、Cost
Stepper motor is advantageous in terms of cost performance, to achieve the same function in the case of servo motor price is greater than the same power stepper motor, servo motor's high response, high speed and the advantages of high precision determines the high price of the product, which is inevitable.
In summary, stepper motors and servo motors both from the working principle, control accuracy, overload capacity, operational performance and cost there are major differences. But the two have their own advantages, users who want to make a choice from them need to combine their actual needs and application scenarios.
Post time: Nov-09-2022