AS64 series AC servo drive Commissioning
-240-
may cause unstable responsiveness of the entire servo system. Perform adjusting in the following
sequence:
1. Set the position loop gain to a small value and increase it to a value as large as possible without
causing abnormal noise or vibration.
2. Decrease the speed loop gain gradually and increase the position loop gain as much as allowed
without causing overshooting or vibration.
3. Decrease the speed loop integral time constant as much as possible without causing vibration since
this time constant is determined by positioning time.
4. Adjust the position loop gain, speed loop gain, and speed loop integral time constant slightly to
achieve optimum settings.
The following describes typical adjusting cases (in the cases except case 1, only one parameter needs
to be adjusted):
⚫
Appropriate parameter settings
In this case, parameters are set appropriately, the motor speed is compliant with the position command,
the speed is not overshot, and positioning time is short.
⚫
Speed loop integral time constant too small
The servo drive speed loop must respond quickly. If the speed fluctuates, the speed loop integral time
constant is too small, which deteriorates the speed loop stableness. Therefore, the running is unstable.
⚫
Speed loop integral time constant too large
The difference from the case of appropriate parameter settings is not noticeable. The speed loop
integral has no significant impact when the speed follows up the position command, but the response
time of the speed loop is impacted if the speed loop integral time constant is too large.
⚫
Speed loop gain too high
In this case, the motor speed fluctuates. If the speed loop integral time is too short, the similar impact
is caused. You must increase both the speed loop gain and the speed loop integral time. Otherwise,
the servo system may encounter vibration.
⚫
Speed loop gain too low
If the speed loop gain is decreased, the motor speed fluctuates. According to the comparison the case
of speed loop gain too large, the fluctuation frequency of the motor speed is lower in this case, which
indicates that increasing the speed loop gain improves the system working frequency, control system
responsiveness, and anti-interference.
⚫
Position loop gain too low
In the servo system, the working frequency of the position loop is lower than that of the speed loop. If
the position loop gain is too low, the system cannot counteract the position deviation that is caused
during speed responding, which delays the interval at which the motor speed follows up the position
command.
⚫
Position loop gain too high
