Answer: Differences between stepper motors and servo motors: Control accuracy, control mode, low-frequency characteristics, overload capacity, operating performance, speed response performance.
Answer analysis:
There are significant differences between stepper motors and servo motors in many aspects, which are mainly reflected in control accuracy, control mode, low-frequency characteristics, overload capacity, operating performance and speed response performance. The following is a detailed analysis of these differences:
1. Control accuracy
Stepper motor: Its control accuracy mainly depends on the number of phases and beats of the motor. The more phases and beats, the higher the accuracy. Generally, stepper motors can achieve higher positioning accuracy, but their accuracy may be slightly inferior to that of servo motors.
Servo motors: They have extremely high position control accuracy, usually reaching a range of a few microns or less. This high accuracy is mainly due to the encoder that comes with the servo motor. The more scales the encoder has, the higher the accuracy.
2. Control method
Stepper motor: Usually uses open-loop control. This means that the stepper motor does not rely on external feedback signals to adjust its movement, but directly controls the rotation of the motor based on the input pulse signal.
Servo motor: Closed-loop control is adopted. The servo motor monitors the position and speed of the motor in real time through the encoder, and feeds this information back to the control system for precise adjustment. This closed-loop control method makes the servo motor perform well in terms of control accuracy and stability.
3. Low-frequency characteristics
Stepper motor: Low-frequency vibration is prone to occur when running at low speed. In order to overcome this problem, damping technology or subdivision technology is usually required to optimize the performance of the motor.
Servo motor: It runs very smoothly and does not vibrate even at low speed. This is due to the resonance suppression function and frequency resolution function (FFT) inside the servo motor, which can ensure that the motor can maintain stable operation under various working conditions.
4. Overload capacity
Stepper motor: Generally does not have overload capacity. When the motor load is too large, it may lose steps or stall.
Servo motor: It has a strong overload capacity. Servo motors can usually withstand working conditions exceeding the rated load for a short time and continue to operate stably after the load returns to normal.
5. Operation performance
Stepper motor: Due to its open-loop control characteristics, it is easy to lose steps or overshoot when the starting frequency is too high or the load is too large.
In addition, the stopping process of the stepper motor may also cause overshoot due to excessive speed.
Servo motor: Due to its closed-loop control characteristics, the driver can directly sample the feedback signal of the motor encoder, and the position loop and speed loop are formed internally. This control method makes the servo motor more stable and reliable during operation, and it is not easy to lose steps or overshoot.
6. Speed response performance
Stepper motor: It takes a long time (usually hundreds of milliseconds) to accelerate from static to working speed.
Servo motor: It has faster speed response performance. Generally, it only takes a few milliseconds to complete the acceleration process, which makes the servo motor have obvious advantages in control occasions that require fast start and stop.
In summary, there are significant differences between stepper motors and servo motors in terms of control accuracy, control mode, low-frequency characteristics, overload capacity, operation performance, and speed response performance. When selecting a motor, these factors need to be comprehensively considered according to the specific application scenario and needs.