As an open-loop control system of stepping motor, and modern digital technology there is an essential link. At present, digital control systems, stepper motors are widely used. With the emergence of fully digital AC servo system AC servo motors are also increasingly used in digital control system. In order to adapt to the development trend of digital control, most of the motion control system using stepper motors or as a force motor Digital AC servo motor. Although the two are similar in control (pulse and direction signal), but there are large differences in properties and applications. Now compare the performance of both.
A, control accuracy of different
Two-phase hybrid stepping motor stride angle is 1.8 °, 0.9 degrees, five-phase hybrid stepping motor stride angle is 0.72 °, 0.36 °. There are some high performance stepper motor through the subdivision will pave the angle is smaller. AC servo motor control precision guaranteed by the rotary encoder of the motor shaft end. With full digital AC servo motors, for example, for motors with encoder standard 2000 lines, due to the internal driver four times times the frequency, pulse equivalent for 360 °/8000=0.045 °. With 17 bit encoder motor, drive round every 131,072 pulse motor, its pulse equivalent for 360 °/131072=0.0027466 °, is the step angle 1.8 ° stepper motor pulse equivalent of 1/655.
Second, low-frequency characteristics
Stepper motor in low speed prone to low frequency vibrations. Vibration frequency and load and drive performance-related, generally considered vibration frequency for motor take off half the frequency. This decided by the stepper motor works of low frequency vibration for the normal operation of the machine is very negative. When stepping motor in low speed, low frequency vibration damping technology should be used to overcome, such as in motors and dampers, or drives using subdivision techniques and so on. AC servo motor run smoothly, even at low speed vibration does not occur. AC servo system with resonant suppression, may cover the insufficient rigidity of the machine and system with frequency analysis functions (FFT), mechanical resonance can be detected, and easy to adjust.