YASKAWA S Series User Manual page 105

Application
5.9.4 Guidelines for Setting the Load Inertia Ratio
II B i a s Control
Positioning
complete
(PSET)
5.9.4 Guidelines for Setting the Load Inertia Ratio
■ Machines with High Rigidity
Load Inertia Ratio
(Cn-0003) [%]
lx (100)
3x (300)
5x (500)
When the number of pulses in the error counter exceeds the positioning complete width
(Cn-001B), bias (Cn-001C) is added to the error counter output (speed reference) until the speed
reference falls within the positioning complete width. This shortens the positioning time by re-
ducing the number of pulses in the error counter.
Motor operation will become unstable if the bias is set too high. Adjust the bias while monitoring
the response because the optimum value will vary with the gain and the positioning complete
width.
Set Cn-001C to 0 if bias control will not be used.
Speed S p e e d
reference
Adjustment guidelines are given below based on the rigidity and load inertia of the mechanical
system. These values are given as guidelines only, and vibration or poor response may occur
within the given ranges. Monitor the response (waveform) to optimize the adjustment. Higher
gain is possible with highly rigid machines.
Machines with high rigidity include ball screws and direct-drive machines.
Examples: Chip Mounters, IC Bonders, Precision Machine Tools
Position Loop
(GD2L/GD2M) Gain (Cn-001A)
[0.01/s]
5000 to 7000
Note As the inertia ratio increases, set the position loop gain and speed loop gain to
the lower limit of the range of values specified and increase the speed loop in-
tegration time constant.
Motor speed without bias control
Motor speed with bias control
Speed Loop Gain
(Cn-0004) [0.1 Hz]
500 to 700
5 -24
Time
Speed Loop Integration
Time Constant (Cn-0005)
[0.01ms]
500 to 2000