THE DIFFERENCES BETWEEN STEPPER MOTOR AND SERVO MOTOR

Servo motors and stepper motors are the two most common motor drives in the industrial control field, what are the differences between them:

1-Controller 

The stepper motor controller is an electronic product that can send out uniform pulse signals. After the signal sent by it enters the stepper motor driver, it will be converted by the driver into the strong current signal required by the stepper motor to drive the stepper motor to run. The stepper motor controller can accurately control the stepper motor to rotate through every angle. What the driver receives is a pulse signal. Every time it receives a pulse, the driver will give the motor a pulse to turn the motor through a fixed angle. Because of this feature, stepper motors are widely used in various industries today. 

A servo motor controller is a controller used to control a servo motor. Its function is similar to that of a frequency converter acting on an ordinary AC motor. It is a part of the servo system and is mainly used in high-precision positioning systems. Generally, the servo motor is controlled through three ways of position, speed and torque to achieve high-precision transmission system positioning. It is currently a high-end product of transmission technology. 

2-Control Accuracy 

The more phases and beats of the stepper motor, the higher its accuracy. The servo motor is based on the built-in encoder. The more scale the encoder has, the higher the accuracy. 

3-Control Methods 

One is open-loop control and the other is closed-loop control. 

4-Low-frequency Characteristics 

Stepper motors are prone to low-frequency vibration at low speeds. Generally, damping or subdivision technology is used to overcome low-frequency vibrations, while servo motors will not vibrate at low speeds. The AC servo system has a resonance suppression function, which can cover the lack of rigidity of the machine, and the system has a frequency analysis function (FFT) inside the system, which can detect the resonance point of the machine to facilitate system adjustment. 

5-Operating Performance 

The stepper motor adopts open-loop control. If the starting frequency is too high or the load is too large, it is easy to lose steps or stall. When the speed is too high, it is easy to overshoot. The servo system is closed-loop control. The drive can directly sample the feedback signal of the motor encoder. The position loop and the speed loop are formed inside. Generally, there will be no step loss or overshoot of the stepper motor, and the control performance is more reliable.