ABB DCS 500B, Description

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Functional Software description
32 DCS 500 Software Description
The output OUT OF WIN (12002) is activated to logical state 1 , if
the value of speed error is outside the window area (defined in pa-
rameter
WIN SIZE (2004) .
SPEED_CONTROL
function block
Gain and Integral
time settings The speed error is formed in the SPEED ERROR function block,
and it is connected to input
IN (2006) . The proportional gain (scal-
ing 100 = 1 gain) KP (2014) and integrator time constant (scaling 1
= 1ms) KI (2018) are the main parameters of the speed controller
PI-function. The output of the integral function can be reset by set-
ting the input
[RINT] (2007) to state 1. Hold function is activated by
setting the input [HOLD] (2012) to logical state 1.
The P-gain re-
duction The adaptive gain of the speed controller is used to smooth out
disturbances which are caused by e.g. low load and backlash.
Moderate filtering of speed error
FRS (2005) is typically not enough
to tune the drive. Especially if there is a substantial backlash in the
drive and the drive oscillates at a low torque due to the mechanics.
Parameter KPSMIN (2015) determines the proportional gain when
the controller output is zero. When the output exceeds the value of
parameter
KPSPOINT(2016) , the proportional gain is normal KP
(2014) . The rate of change of the proportional gain can be smooth-
ened by means of parameter KPSWEAKFILT (2017) .
KPSMIN
(2015)
KP (2014)
KPSPOINT (2016)
OUT (12004)
Torque ref.
Figure 17 Reduction of gain as a function of torque reference
Output Limitation The speed control output OUT (12004) is limited by the
TORQUE/CURRENT LIMITATION function block (SPC
TORQMAX1 and SPC TORQMIN1). Output
IN LIMIT (12005) is in
logical state 1, when the output of the speed controller is in positive
or negative limit.