B&R ACOPOSinverter P84, Руководство пользователя

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Programming guidelines
ACOPOSinverter P84 User's Manual 2.10 251
Diagram
PID error (RPE)
PID output (RPO)
Reference applied
to motor
If the delta of error (negative value) is
multiplied by the RPG, the result is that
we have a down ramp on the output.
This ramp will be faster than the error
reduces since we are multiplying the value with a
gain value: PID output = deltaError x RPG
Since the PID feedback is linear, the delta of
the error between n and n-1 is always the same
value. And even if the error is positive, the
delta of error will be negative: n - (n-1) > 0.
This negative value for the delta of the error is multiplied
by a gain value (positive)
t(s)
t(s)
Conclusion and recommendation
•
In our inverters PID output is calculated by multiplying the RPG-value (gain) with the delta value of the error.
Even in the case of a positive error, the delta value of the error is negative if this error reduces. The delta
value of the error is multiplied by the RPG-value. For this reason with a high RPG-value the PID output is
a falling ramp up to 0 (or reversal operation at POL < 0).
• If the motor has also been stopped in the event of a change of the PID reference, the motor starts, but
follows the AC2 parameters. This is not the case if the inverter is in RUN mode and the PID reference
variable is moved.
• For correct behavior, the PID must be adjusted. Proportional gain cannot be used alone. The same applies
for the integral gain - it cannot be completely suppressed. You can have a minimum value of 0.01 for it,
but it is always present.
The points 1 and/or 2 may be the result of a poor positioning at the customer site.