26 • vacon
Description of parameters
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Example 1:
In order to reduce the error value to zero, with the given values, the frequency converter output
behaves as follows:
Given values:
Par. 2.1.12, P = 0%
Par. 2.1.13, I-time = 1.00 s
Par. 2.1.14, 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 I-controller only.
According to the given value of parameter 2.1.13 (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.
Figure 3. PID controller function as I-controller.
Example 2:
Given values:
Par. 2.1.12, P = 100%
Par. 2.1.13, I-time = 1.00 s
Par. 2.1.14, D-time = 1.00 s
Min freq. = 0 Hz
Error value (setpoint – process value) = 10%
Max freq. = 50 Hz
As the power is switched on, the system detects the difference between the setpoint and the
actual process value and starts to either raise or decrease (in case the error value is negative)
the PID output according to the I-time. Once the difference between the setpoint and the
process value has been reduced to 0 the output is reduced by the amount corresponding to the
value of parameter 2.1.13.
In case the error value is negative, the frequency converter reacts reducing the output
correspondingly. See Figure 4.
Hz
t
1s
Error=10%
10%
10%
10%
10% I-Part=5 Hz/s
I-Part=5 Hz/s
I-Part=5 Hz/s
I-Part=5 Hz/s
I-Part=5 Hz/s
PID output
Error value
NX12k70
