YASKAWA SGD7S series Product Manual page 58

3.3 Adjusting Less-Deviation Control 2
3.3.2 Adjustment Example
The effects of Pn19B are shown below.
The torque reference and
torque feedforward do not
agree due to viscous friction.
Position reference
Torque reference
Torque feedforward
Position deviation
Adjustment Example for Less-Deviation Control 2 Incom-
plete Integration Rate (Pn19A)
With less-deviation control, the position integral is used to bring the position deviation close to
0 during constant-speed operation. However, a long period of time is normally required for the
position deviation to converge to 0 with only position integration. To reduce that trend, the
incomplete integral, for which the integral effect falls off with time, is also used. The default set-
ting of Pn19A is 10,000 (100%). In other words, 100% of the previous output from integrator
will be subtracted from the current input to the integrator every control cycle.
Therefore, when the deviation settles, the effectiveness of the position integral is lost. However,
you can adjust this parameter to increase positioning capability when stopping if you are willing
to accept a somewhat longer settling time. If you set this parameter to 0%, operation will be
the same as for a normal integrator.
Position reference
Position deviation
3-8
Before Adjustment ： Pn19B = 0 (0.00%/min
speed
0 100 200
Time (ms)
Before Adjustment ： Pn19A = 0 (0.0%)
speed
0 175 350
Time (ms)
-1 )
The torque reference and
torque feedforward agree.
Position reference
Torque feedforward
Position deviation
300 400 500
Position reference
Position deviation
525 700 875
After Adjustment ： Pn19B = 75 (0.75%/min
speed
Torque
reference
Position deviation
is reduced.
0 100 200
Time (ms)
After Adjustment ： Pn19A = 100 (100.0%)
speed
0 175 350 525
Time (ms)
-1 )
300 400 500
Convergence time is reduced.
However, positioning capability
is also reduced.
700 875