There are significant differences between AC servo motors and stepper motors in several aspects，Here are six key differences：

1. Different control methods

• Stepper motor：Open loop control is usually used，That is, the control mode without position feedback。It drives the motor to rotate at a fixed Angle according to the input pulse signal（Step Angle），The actual position of the motor is not directly detected。

• Ac servo motor：Closed-loop control，Have location、Independent controls such as speed and torque。It detects the actual position of the motor in real time via an encoder or other position sensor，And compare with the target position，Thus, the control signal of the motor is adjusted，Achieve high precision position control。

2. Different control accuracy

• Stepper motor：The control accuracy is relatively low，Especially at high speeds，Due to the cumulative error of step Angle，Its accuracy will be further reduced。merely，The control precision of stepper motor can be improved by subdivision drive technology to a certain extent。

• Ac servo motor：High control accuracy，It can achieve positioning accuracy at the micron or even nanometer level。Its closed-loop control system can correct errors in real time，Make sure the motor is moving exactly according to the predetermined trajectory。

3. Different dynamic performance

• Stepper motor：It has good dynamic performance at low speed，However, out-of-step or resonance phenomena may occur at high speed，The dynamic performance is affected。

• Ac servo motor：It has excellent dynamic performance，Able to maintain stable performance output at high speeds，It is not easy to appear out of step or resonance phenomenon。

4. Different response speed

• Stepper motor：The response is relatively slow，Especially in situations where rapid positioning or shifting is required，Its response speed may not meet the requirements。

• Ac servo motor：The response time is extremely fast，It can reach the predetermined position and speed in a very short time，Meet high speed、High precision control requirements。

5. Different overload capacity

• Stepper motor：The overload capability is weak，When the load is too large or the startup frequency is too high，It is easy to lose step or block rotation。

• Ac servo motor：Has a strong overload capacity，It can withstand large load impact in a short time，And maintain stable performance output。

6. Different application fields

• Stepper motor：Because of its simple structure、Low cost and easy to control，Therefore, it is widely used in some occasions where the accuracy and dynamic performance are not required，Such as industrial automation、Office equipment、Home appliances。

• Ac servo motor：Due to its high accuracy、High performance and excellent dynamic performance，It is widely used where precise control of position is required、Speed and torque of the occasion，Such as CNC machine tools、Robot、Automation equipment、Optical instrument、Medical equipment and other fields。

To sum up，Ac servo motor and stepper motor in the control mode、Control accuracy、Dynamic performance、Response speed、There are significant differences in overload capacity and application fields。When choosing a motor，Comprehensive consideration should be made according to specific application requirements and environmental conditions。