SLX9000 Adjustable Frequency Drives User Manual
9-34 For more information visit: www.eaton.com
MN04003020E
January 2009
Figure 9-25: PID Controller Function as I-Controller
2.9.6 PID controller D-time ID132
The parameter 2.9.5 defines the derivative time of the PID controller. If this
parameter is set to 1.00 second, a change of 10% in the error value during 1.00 s
causes the controller output to change by 10.00%. If the parameter value is set to
0.00 s, the PID controller will operate as PI-controller.
See examples below.
Example 1:
In order to reduce the error value to zero, with the given values, the drive output
behaves as follows:
Given values:
Par. 2.9.4, P = 0% PID max limit = 100.0%
Par. 2.9.5, I-time = 1.00 s PID min limit = 0.0%
Par. 2.9.6, D-time = 0.00 s Min freq. = 0 Hz
Error value (setpoint - process value) =
10.00%
Max freq. = 50 Hz
In this example, the PID controller operates practically as ID-controller only.
According to the given value of parameter 2.9.5 (I-time), the PID output increases by
5 Hz (10% of the difference between the maximum and minimum frequency) every
second until the error value is 0.
10%
10%
10%
10%
Error = 10%
PID Output
Error Value
I-Part = 6 Hz/s
I-Part = 6 Hz/s
I-Part = 6 Hz/s
I-Part = 6 Hz/s
I-Part = 6 Hz/s
1s
Hz
t
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