The stepper motor purchased from the printer motor generally does not have overload capacity, and the AC servo motor has a strong overload capacity. The Panasonic AC servo system, for example, has both speed overload and torque overload capabilities. Its maximum torque is three times the rated torque and can be used to overcome the moment of inertia of inertial load at the moment of start-up.
Because the motor does not have this overload capacity, in order to overcome this moment of inertia, it is often necessary to select a large torque motor, and the machine does not need so much torque during normal operation, so the phenomenon of torque waste occurs.
The control of stepper motor is open-loop control. If the starting frequency is too high or the load is too high, it is easy to lose step or block rotation. If the speed is too high when stopping, it is easy to overshoot.
Ac servo drive system is closed loop control, the driver can directly sample the feedback signal of the motor encoder, and the internal structure of position ring and speed ring, generally there will be no step loss or overshot of the stepper motor, the control performance is more reliable.
