Various motors are needed in many fields, including well-known stepper motors and servo motors. However, for many users, they do not understand the main differences between the two motors, so they always do not know how to choose. So, what is the main difference between stepper motor and servo motor?
1. Working principle
The two types of motors are very different in principle. Stepping motor is an open-loop control element stepping motor that converts electric pulse signal into angular displacement or linear displacement. Check the working principle of stepping motor.
The servo mainly relies on pulses to locate. The servo motor itself has the function of sending pulses, so each time the servo motor rotates an angle, it will send out a corresponding number of pulses, so that it echoes with the pulses received by the servo motor, or called closed loop, so that the system will know how many pulses are sent and received back, so that it can accurately control the rotation of the motor and achieve accurate positioning.
2. Control accuracy
The accuracy of the stepping motor is generally achieved through the precise control of the step angle. The step angle has a variety of different subdivision gears, which can achieve precise control.
The control accuracy of the servo motor is guaranteed by the rotary encoder at the rear end of the motor shaft. Generally, the control accuracy of the servo motor is higher than that of the stepper motor.
3. Speed and overload capacity
The stepping motor is prone to low-frequency vibration when operating at low speed, so when the stepping motor is operating at low speed, damping technology is usually needed to overcome low-frequency vibration phenomenon, such as adding damper on the motor or adopting subdivision technology on the driver, while the servo motor does not have this phenomenon, and its closed-loop control characteristics determine its excellent performance when operating at high speed. They have different torque-frequency characteristics. Generally, the rated speed of servo motor is greater than that of stepping motor.
The output torque of the stepping motor will decrease with the increase of the speed, while the servo motor is constant torque output, so the stepping motor generally has no overload capacity, while the AC servo motor has strong overload capacity.
4. Operational performance
Stepping motor is generally open-loop control, which may cause out-of-step or locked-rotor phenomenon when the starting frequency is too high or the load is too large. Therefore, it is necessary to deal with the speed problem or increase the encoder closed-loop control to see what is closed-loop stepping motor. The servo motor adopts closed loop control, which is easier to control without out-of-step.
Stepping motors have advantages in cost performance. To achieve the same function, the price of servo motors is higher than that of stepping motors with the same power. The high response, high speed and high precision of servo motors determine the high price of products, which is inevitable.
To sum up, there are great differences between stepper motor and servo motor in terms of working principle, control accuracy, overload capacity, operation performance and cost. However, both have their advantages. If users want to choose from them, they need to combine their actual needs and application scenarios.
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