Torque Reference; Torque Reference Scaling; Load Sharing In Master / Follower Application; Output Limitation - ABB DCS 500B Description

• Torque Reference

TORQ_REF_SELECTI
ON function block
Torque Refer-
ence Scaling
Load sharing in
Master / Follower
Application

Output Limitation

TORQUE/CURRENT_
LIMITATION function
block
Current Limita-
tions
DCS 500 Software Description
The function of the torque reference chain is to form a desired ref-
erence for the current regulation.
An external torque reference can be connected via analog inputs.
AI2 function block is connected to [TREF A] (2401) in the standard
program, and this input contains a filter controlled by parameter
TREF A FTC (2402) (1000 = 1s), 0 = not in use.
[TREF B] (2404) input is another torque reference input, which
contains the ramp generator function controlled by parameter
TREF B SLOPE (2405) (1000 = 1s), 0 = not in use.
The value 4000 is equal to nominal torque of the DC-motor (T N ).
Therefore the analog input must be scaled according to this value.
For example, an external torque reference -10V...+10 V is con-
nected to analog input AI2 and the torque reference should be
-100%...+100% of the motor nominal torque. The parameter set-
tings are:
AI2 CONV MODE (107)
AI2 HIGH VALUE (108)
AI2 LOW VALUE (109)
The load of the follower drive can be adjusted by means of input
[LOAD SHARE] (2403) to the desired value by the application
function blocks. The default value is 100 % = 4000.
The output OUT (12401) is calculated:
[TREF A] x [LOAD SHARE] / 4000 + [TREF B]
The final torque reference before limitation is a sum of a [TREF A]
multiplied by [LOAD SHARE] and [TREF B].
The output OUT (12401) can be limited by internal signals [TREF
TORQMAX1] and [TREF TORQMIN1] in the function block
TORQUE / CURRENT LIMITATION.
Torque / Current Limitation function block consist of limitation cir-
cuits for torque and current references and gear backlash compen-
sation.
The limitation of armature current is based on fixed current limit pa-
rameters and on limits which are the function of the actual speed.
There is a function block with given points of speed and maximum
current on these points. Finally the current limit selection is based
on a maximum/minimum selection of these two limitation sources.
Functional Software description
= 1
= 4000
= -4000
37