Yaskawa iQpump Drive User Manual - Manual (Page 100)

5.1 iQpump Basic Programming Parameters
100 YASKAWA TM.iQp.01 iQpump Drive User Manual
Figure 5.13
Figure 5.16 PI Feedback Response Characteristics
■ b5-04 Integral Limit Setting
Setting Range: 0.0 to 100.0%
Factory Default: 100.0%
On some applications, especially those with rapidly varying loads, the output of the PI function may have large oscillations. To suppress
these oscillations, a limit can be applied to the integral factor by programming b5-04.
■
b5-06 PI Output Limit
Setting Range: 0.0 to 100.0%
Factory Default: 100.0%
Places a cap on the output of the PI function. Limiting the PI function may help to prevent large overshoots in the iQpump drive’s
response to error (the difference between the setpoint and the feedback).
■
b5-07 PI Offset Adjustment
Setting Range: -100.0% to +100.0%
Factory Default: 0.0%
The PI Offset Adjustment parameter has two different uses. Parameter b5-07 serves different functions depending on whether it is used
on a standard PI loop or a Differential PI loop.
Parameter b5-07 causes an offset to be applied to the output of the PI function in a non-Differential PI loop. Every time the PI output is
updated, the offset (b5-07) is summed with the PI output. This can be used to artificially kick-start a slow starting PI loop.
If the iQpump drive is configured for Differential PI Regulation (H3-09 = “16: PI differential”), then this parameter is the target setpoint
for the differential to be maintained between the signal measured on analog input A1 and the signal measured on analog input A2.
■
b5-08 PI Primary Delay Time Constant
Setting Range: 0.00 to 10.00 sec
Factory Default: 0.00 sec
Acts as a time based filter that lowers the responsiveness of the PI function, but also makes the function more stable when the setpoint
varies rapidly or when the feedback is noisy.
Zero
offset with
Integral Action
No Integral With Integral
Measur
ed Feedb
ack
Mea
su
red Feedb
ack
Setpoint
Offset
Setpoint
Feedback Feedback
TIME TIME