When selecting the motor, the selection will be made according to the customer's requirements and the characteristics of the linear module. Generally, stepper motors are suitable for low-speed occasions; servo motors are suitable for high-precision and high-speed occasions. In addition to the linear module, the first motor must comprehensively consider the control requirements, cost and other factors, and select the appropriate control motor.
So what are the differences between stepper motors and servo motors? Let's take a look first!
The stepper motor is a discrete movement device, which has an essential connection with modern digital control technology. In the current domestic digital control system, stepper motors are widely used. With the advent of all-digital AC servo systems, AC servo motors are increasingly used in digital control systems. In order to adapt to the development trend of digital control, most of the motion control systems use stepper motors or all-digital AC servo motors as executive motors. Although the two are similar in control methods (pulse train and direction signal), there are big differences in performance and applications. Now make a comparison of the performance of the two.
In summary, the following aspects are:
(1) The control accuracy is different. The control accuracy of the AC servo motor is guaranteed by the rotary encoder at the back of the motor shaft
(2) The low-frequency characteristics are different. The stepper motor is prone to low-frequency vibration at low speed; the AC servo motor runs very smoothly, and there is no vibration even at low speed.
(3) The torque-frequency characteristics are different. The output torque of the stepping motor decreases with the increase of the speed, and will drop sharply at higher speed.
(4) Different overload capacity, stepper motors generally do not have overload capacity. AC servo motors have strong overload capacity.
(5) The operation performance is different. The control of the stepping motor is 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 cause overshoot. To ensure the accuracy of its control, the speed-up and speed-down problems should be handled well. The AC servo drive system is a closed-loop control. The drive can directly sample the feedback signal of the motor encoder. The position loop and speed loop are formed inside. Generally, the stepper motor will not lose steps or overshoot, and the control performance is more reliable.
(6) The speed response performance is different. It takes 200 to 400 milliseconds for a stepper motor to accelerate from a standstill to a working speed (generally several hundred revolutions per minute). The acceleration performance of the AC servo system is better.
Therefore, when choosing a linear module motor, you must follow your own needs, and the one that suits you is the best.
