Yaskawa SGDB - Manual (Page 552)

SERVO ADJUSTMENT
A.2.2 Manual Adjustment cont.
544
However, the integration time constant must be increased to prevent machine vibration
if the load inertia is large or the mechanical system includes a element that is prone to
vibration.
The following formula calculates a guideline value.
Ti: Integration Time Constant (sec)
Kv: Speed Loop Gain (Hz) (calculated above)
Ti ≥ 2.3 ×
1
2π × Kv
• Torque Reference Filter Time Constant (Cn-17)
When a ball screw is used, torsional resonance may occur which increases the pitch of
the vibration noise.
This vibration can sometimes be overcome by increasing the torque reference filter
time constant.
However, this filter will produce a delay in the servo system, just like the integration time
constant, and its value should not be increased more than necessary.
• Speed Reference Gain (Cn-03)
Changing the speed reference gain (Cn-03) changes the position loop gain an equiva-
lent amount. That is, reducing the speed reference gain is equivalent to reducing the
position loop gain and increasing it is equivalent to increasing the position loop gain.
Use this parameter (Cn-03) in the following circumstances:
• No position loop gain adjustment at host controller (including cases where fine ad-
justment not possible by changing number of D/A converter bits)
• Clamping the speed reference output range to specific speeds
Normally leave at the factory setting.
NOTE For a speed-control SGD or SGDA SERVOPACK, or SGDB or DR2 SERVOPACK used for
speed control, the position loop gain (Cn-1A) is valid in zero-clamp mode only.
The position loop gain (Cn-1A) parameter is always invalid for a DR1 SERVOPACK.
For normal control, change the position loop gain at the host controller or adjust the speed
reference gain (Cn-03) in the SERVOPACK.
Changing Cn-1A does not change the position loop gain.
J Adjustment Procedure
1. Set the position loop gain at the host controller to a low value and increase the speed
loop gain (Cn-04) within the range that no abnormal noise or vibration occurs.
If adjustment of the position loop gain is not possible at the host controller, reduce the
speed reference gain (Cn-03).
2. Slightly reduce the speed loop gain from the value at step 1, and increase the position
loop gain at the host controller in the range that no overshooting or vibration occurs.
If adjustment of the position loop gain is not possible at the host controller, increase
the speed reference gain (Cn-03).
A