gefran ADP200 User Manual page 60

From the graph is possible to see that in injection phase the speed is higher than the holding phase
at the same level pressure. In general, due to hydraulic model, in the injection phase the pressure
gain during the injection phase should be higher than the holding phase. The gain scheduling works
in this direction allowing the user to increase the gain of the pressure loop at high speed. So to get
best performance the user can adapt the gain for these 2 condition (higher gains at higher speed).
b) Reduce overshoot during transition.
There is also a further benefits by using the gain scheduling that help to reduce the overshoot during
the transition. The reason is the interaction between the gain scheduling and the internal variables of
PI control. Higher value of the Proportional value at high/medium speed allow to create a fast
response during the transition from speed control to pressure control.
So as suggestion, if there is issue about pressure overshoot during transition, one way to try to solve
it is to increase the proportional gain (IPA 11162 and IPA 11168).
Variable gain (Multilevel PID)
In addition to existing parameters relating to gain-scheduling, they can also be changed using a digital control
or fieldbus (through WDecomp).
As a result, pressure control response dynamics can be altered in relation to a PLC command, which, for
example, may be linked to a processing phase change or any other information known by the same PLC.
In addition to standard operation, three additional proportional (kp) and integral (ki) pressure gain sets can be
set.
The gains used will not be offset using the Gain Scheduling method, which is only applied to the basic setting.
A command defined by IPA 11180, 11182, 11184, 11186 enables transition from set 0 (standard gains), to set
1 (IPA 11188, 11190), to set 2 (IPA 11192, 11194) and to set 3 (IPA 11196, 11198).
Gain transition occurs with a filter with a time constant equal to parameter 11200.
The combination of parameters 11184 and 11186, as well as from the fieldbus (through Wdecomp), allows for
gains to be programmed with digital HW inputs (this should be the main use).
With a digital bus, an SDO can be programmed directly on the digital command PAR 11182 and the desired
parameter setting can be written directly in a transition.
If parameter 11180 is ON (default condition), the parameter set is set by a digital command through parameter
11182 (default = 0).
If parameter 11180 is OFF, the parameter set is determined by the combination of 2 bits. The lower bit's source
is given by parameter 11184 MGain Term Source 1 while that of the upper bit by parameter 11186 MGain
Term Source 2.
In general, the following scenario is possible:
ADP200 Application PID-IMM
P
Pressure
Control Area during Holding
Figure 1: Example of Injection to holding phase transition
User Manual
Holding phase
(after injection)
Injection
Q Flow
Control Area during Injection
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