Adaptive Speed Parameters - Santerno DCREG2 Series User Manual

15P0059B3
USER MANUAL

ADAPTIVE SPEED PARAMETERS

6 . 9
When the speed reference value is suddenly changed and the load speed is not able to follow such
variation, the speed loop proportional gain in the transient is to be large enough to avoid any excessive
speed overshot both during acceleration and deceleration. On the other hand, once the speed is
constantly kept at the new value set, said value is generally too high for the speed loop and may cause
some instability.
DCREG allows to enable the ADAPTIVE SPEED PARAMETERS mode through par. P082 (AdaptCtrl).
This parameter allows the proportional gain to have a rather high value, selected through par. P073
(KpSpdAdapt) when also speed error value Verr is remarkable - so when the speed value has not yet
reached the reference value. When the load speed reaches the new value set, so the speed error
decreases until it becomes null, the proportional gain is gradually reduced until it reaches the original
value set in par. P070 (KpSpeed): the transition between the two values is not sudden but it gradually
occurs between the error value set in par. P083 (Verr1) and the one set in par. P084 (Verr2).
This may be seen in the figure below.
The adaptive speed parameters also control the speed loop integral time. During the transient, the
integral time may be changed starting from the original value set in par. P071 (TiSpeed) up to the new
value set in par. P074 (TiSpdAdapt). In that case as well, the transition between the two values gradually
occurs between the error value set in par. P083 (Verr1) and the one set in par. P084 (Verr2).
Two opposite cases are shown below, requiring an opposite integral time change.
1. Constant-load quick reference change. This may happen with an inertial load, when the drive is in
current limit mode due to a sudden speed reference change.
In that case, to avoid any speed overshot at the transient end, the proportional gain is to be temporarily
increased and the integral time is to be longer, as is shown in the figure below.
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