Lenze i550

Fine adjustment of the PID controller
The dynamics of the PID controller are parameterised based on the gain of the P component
0x4048 (P601.00), the reset me for the I component 0x4049 (P602.00) and the gain of the D
component 0x404A (P603.00). In the default seng, the process controller operates as a PI
controller. The D component is deacvated.
Basics
•
If only the P component is used and the system operates in a steady-state status (the refer-
ence value is constant and the process variable is controlled to a xed value), a certain sys-
tem deviaon always connues to exist. This remaining system deviaon is also called "sta-
onary deviaon".
•
The I component prevents a permanent uctuaon around the setpoint. Here, the reset
me 0x4049 (P602.00) determines how much the duraon of the control deviaon inu-
ences the control. A high reset me means a lower inuence of the I component and vice
versa.
•
The D component does not respond to the height of the system deviaon but to their rate
of change only. The D component acts as a "damper" for overshoots. Overshoots may
occur if the control tries to respond quickly to changes in the system deviaon or the refer-
ence value. Thus, the D component reduces the risk of instabilies due to overshoots.
For most applicaons, the seng of the gain of the P component and the reset
me for the I component is sucient for the ne adjustment. The seng of the
gain of the D component may by required for a further stabilisaon of the sys-
tem especially if a quick response to system deviaons is to take place.
Execute ne adjustment:
1.
Set the reset me for the I component to 6000 ms in 0x4049 (P602.00) to deacvate the I
component.
•
With this seng and the default seng of 0x404A (P603.00), the process controller
operates as P controller.
2.
Increase gain of the P component step by step in 0x4048 (P601.00) unl the system
becomes instable.
3.
Reduce the gain again unl the system is stable again.
4.
Reduce the gain by another 15 %.
5.
Set reset me for the I component in 0x4049 (P602.00).
•
With this seng it should be noted that a too low reset me may cause overshoots,
especially in case of high steps of the system deviaon.
6.
Oponal: set the gain of the D component in 0x404A (P603.00).
•
With this seng it should be noted that the D component responds very sensively to
electrical disturbance on the feedback as well as digisaon errors.
Conguring the frequency control
Conguring the process controller
Basic seng
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