Gain And Integral Time Settings; The P-Gain Reduction; Output Limitation - ABB DCS 500B Description

Functional Software description
SPEED_CONTROL
function block
Gain and Integral
time settings
The P-gain re-
duction

Output Limitation

32
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).
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 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).
KP (2014)
KPSMIN
(2015)
KPSPOINT (2016)
Figure 17 Reduction of gain as a function of torque reference
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.
OUT (12004)
Torque ref.
DCS 500 Software Description