1. Control precision
The more phases and steps a stepper motor has, the higher its accuracy. Similarly, a servo motor uses its own encoder, and the more scales the encoder has, the higher its accuracy.
2. Control Method
One is open-loop control, and the other is closed-loop control.
3. Low-frequency characteristics
Stepper motors are prone to low-frequency vibration at low speeds. When operating at low speeds, damping or microstepping techniques are generally used to overcome this low-frequency vibration. Servo motors operate very smoothly and do not vibrate even at low speeds.
4. Moment-frequency characteristics
The output torque of a stepper motor decreases as the speed increases, while an AC servo motor provides constant torque output.
5. Overload capacity
Stepper motors generally do not have overload capacity, while AC motors have a strong overload capacity.
6. Operating performance
Stepper motors are controlled in an open-loop manner. If the starting frequency is too high or the load is too large, step loss or stalling may occur. If the speed is too high when stopping, overshoot may occur. AC servo drive systems are controlled in a closed-loop manner. The driver can directly sample the feedback signal from the motor encoder and internally form a position loop and a speed loop. Generally, step loss or overshoot will not occur with stepper motors, and the control performance is more reliable.
7. Speed Response Performance
Stepper motors take hundreds of milliseconds to accelerate from a standstill to their operating speed, while AC servo systems have better acceleration performance, typically requiring only a few milliseconds, making them suitable for control applications requiring rapid start and stop.
