Internal Current Control In Vvc Plus Mode - Danfoss VLT Decentral Drive FCD 302 Design Manual

Product Overview
The short circuit behaviour depends on the 3 current
transducers in the motor phases and the desaturation
protection with feedback from the brake.
2 2
L1 91
L2 92
L3 93
Illustration 2.3 Control Principle
2.1.2 Internal Current Control in VVC
Mode
The frequency converter features an integral current limit
control which is activated when the motor current, and
thus the torque, is higher than the torque limits set in
4-16 Torque Limit Motor Mode, 4-17 Torque Limit Generator
Mode and 4-18 Current Limit.
When the frequency converter is at the current limit during
motor operation or regenerative operation, it reduces
torque to below the preset torque limits as quickly as
possible, without losing control of the motor.
Smart Logic Control (SLC) is essentially a sequence of user-
defined actions (see 13-52 SL Controller Action [x]) executed
by the SLC when the associated user-defined event (see
13-51 SL Controller Event [x]) is evaluated as TRUE by the
SLC.
The condition for an event can be a particular status or
that the output from a Logic Rule or a Comparator
Operand becomes TRUE. That leads to an associated
Action as illustrated in Illustration 2.4.
12
®
VLT Decentral Drive FCD 302
R inr
P 14-50
plus
®
MG04H102 - VLT is a registered Danfoss trademark
Inrush
Par. 13-51
SL Controller Event
Running
Warning
Torque limit
Digital inpute X 30/2
. . .
Par. 13-43
Logic Rule Operator 2
. . .
. . .
Par. 13-43
Comparator Operator
=
TRUE longer than..
. . .
. . .
Illustration 2.4 Current Control Status/Event and Action
Events and actions are each numbered and linked together
in pairs (states). This means that when [0] event is fulfilled
(attains the value TRUE), [0] action is executed. After this,
the conditions of [1] event will be evaluated and if
evaluated TRUE, [1] action will be executed and so on. Only
one event will be evaluated at any time. If an event is
evaluated as FALSE, nothing happens (in the SLC) during
the current scan interval and no other events will be
evaluated. This means that when the SLC starts, it
evaluates event [0] (and only [0] event ) each scan interval.
Only when [0] event is evaluated TRUE, will the SLC
Brake
R+
82
Resistor
R-
81
U 96
V 97
M
W 98
Par. 13-51
SL Controller Action
Coast
Start timer
Set Do X low
Select set-up 2
. . .