Chapter
3
- Functional Description
DCS 500 12-Pulse Planning and Start-Up
3 - 3
Dynamic response
The dynamic response of the 12-pulse configuration is delayed in
comparison to the 6-pulse power converter (master) by:
+ 0.5 of a cycle because of the 30-degree-offset mains feed to
the slave
+1 - 2 cycles because of the special feature incorporated for
bridge reversal (see under “Bridge reversal”)
+2 - 3 cycles because of the analog current reference and actual
current transmission
The signals are processed independently of each other for each
power converter.
Current feed-
back/reference
A current reference signal is transmitted from the master to the
salve in analog form, and the current feedback value (again in
analog form) from the slave to the master.
The standard terminals used at AI2 and AO2 (see the block dia-
gram). The signals concerned are bipolar, but this does not matter,
since the polarity is already being transmitted via Plug Connector
X18.
AI2 and AO2 are processed in the 5 ms task. The polarity signals
are transmitted in the cyclical task of 3.3 ms (at 50 Hz). This will
likewise produce time-delays amounting to two to three times the
cycle time.
Current refer-
ence, Master-
Slave
Master:
This transmits the current reference (see the block diagram in the
section on “Control Structure” further on in this chapter).
This signal is outputted here through AO2 to X4:8 (SDCS-IOB-1)
before current limitation (Parameter 406). The polarity of this signal
is irrelevant for the slave, since it is transmitted digitally through
X18.
Slave:
The current reference is inputted at Terminal X3:8 at the analog in-
put AI2 (IOB-1) and is then connected internally at Pointer 3604 to
the 12-PULSE LOGIC block. Here, too, the polarity is not directly
evaluated.
Terminals X4:8 (Master) and X3:8 (Slave) must be connected to
each other using a cable of >1 mm².
For the 12-pulse function, the current limitation parameters (406),
(2307) and (2308) must all be set to the same size.
