Yaskawa Large Capacity Sigma II Series - Manual (Page 213)

5 Servo Adjustment
5.4.3 Making Manual Adjustments
5-30
• Torque Reference Filter Time Constant (Pn401)
If the mechanical system uses ball screws, torsion resonance may result, in which case
the oscillation noise will be a high-pitched tone. The oscillation may be stopped by
increasing the time constant of the torque reference filter. Like the integral time con-
stant, this filter causes a delay in the operation of the servo system. Therefore, this con-
stant must not be set to an excessively large value.
• Speed Reference Input Gain (Pn300)
Changing the speed reference input gain set in Pn300 is equivalent to changing the posi-
tion loop gain. In other words, an increase in the speed reference input gain set in Pn300
is equivalent to a decrease in the position loop gain and vice versa. Use this parameter in
the following cases.
• When the host controller does not have a function for adjusting the position loop
gain.
(The host incorporates a D/A converter to change the number of bits but cannot make
fine adjustments of position loop gain.)
• When it is necessary to clamp the full range of the speed reference output of the host
device to a specified rotation speed.
In normal operation, the factory-set value can be used as it is.
If the SERVOPACK is used for speed control, the position loop gain set in Pn102 is enabled in zero-
clamp mode only. In normal control operation, change the position loop gain through the host or
change the speed reference input gain in Pn300 in the SERVOPACK. The position loop gain remains
the same if the setting in Pn102 is changed.
Adjustment Procedure
1. Set the position loop gain to a comparatively low value in the host device. Then increase
the speed loop gain set in Pn100 to within a range where there is no noise or oscillation
resulting.
If the position loop gain cannot be changed through the host device, increase the speed
reference input gain set in Pn300 to a larger value.
2. Decrease the speed loop gain a little from the value set in step 1. Then increase the posi-
tion loop gain through the host controller to within a range where there is no noise or
oscillation resulting.
As in step 1., decrease the set value of Pn300 if the position loop gain cannot be changed
through the host device.
3. Set the speed loop integral time constant in Pn101 while observing the positioning set-
ting time and the vibration of the mechanical system. If the constant is too large, posi-
tioning setting time will be long.
4. Set the torque reference filter to a small value in Pn401 if the mechanical system does
not have shaft torsion resonance. If the mechanical system generates oscillation noise in
a high-pitched tone, shaft torsion resonance may be occurring. In that case, set Pn401 to
INFO