The difference between the stepping motor and servo motor

The difference between stepping motor and servo motor are:

1, Control accuracy is different; The more the number of phases and the number of beats of the stepping motor, the higher the accuracy, the servo motor depends on its own encoder, the more the encoder scale, the higher the accuracy.

2, Control mode is different; one is open-loop control, another is closed-loop control.

3, Different low frequency characteristics; stepping motor prone to the phenomenon of low frequency vibration at low speeds, when it works at low speed generally use damping technology or subdivision technology to overcome low frequency vibration phenomenon, the servo motor is running very smoothly, even at low speeds does not appear vibration phenomena. AC servo system has a resonance suppression function, can cover the insufficient of mechanical stiffness and the system has a function of frequency analysis (FFT), can detect mechanical resonance point convenient for system adjustment.

4, Different torque frequency characteristics; stepper motor output torque will decrease with the increase of the rotating speed, and AC servo motor is a constant torque output.

5, The overload capacity is different; the stepping motor generally does not have the overload capacity, but the AC motor has the strong overload ability.

6, Different operating performance; stepper motor control is open-loop control, the starting frequency is too high or the load is too large is easy to lose step or blocking phenomenon, stop with excessive rotating speed prone to overshoot phenomenon, AC servo drive system is the closed-loop control, the motor encoder feedback signal can be sampled directly by drives, the internal structure of the position loop and speed loop, generally does not appear stepper motor lost step or overshoot phenomenon, control performance is more reliable.

7, Speed response performance is different; stepper motor to accelerate from standstill to operating speed required hundreds of milliseconds, and AC servo system has better acceleration performance, generally only a few milliseconds, can be used for applications require fast start and stop control.

Source: http://www.machineballscrew.com Ball Screw Assemblies