Yaskawa DR2 Sigma Servo - Manual (Page 445)

SERVO ADJUSTMENT
B. 2 .2 Manual Adjustment cont.
434
b) Speed Loop Integration Time Constant (Cn-05)
The speed loop has an integration element to allow response to micro-inputs.
This integration element can produce a delay in the servo system, and the positioning
setting time increases and response becomes slower as the time constant increases.
However, the integration time constant must be increased to prevent machine vibra-
tion 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
c) 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.
d) Speed Reference Gain (Cn-03)
Changing the speed reference gain (Cn-03) changes the position loop gain an equiv-
alent 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 user constant (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) user constant 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.
B