Functional Software description
DCS 500 Software Description 85
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12 pulse configuration
The 12- pulse parallel connection produces the following advan-
tages:
- reduction in power converter´s effects on the mains supply net-
work, like reduced harmonics and different frequencies
- large output DC currents; doubling of the output current due to
parallel connection of two 6-pulse standard power converters
- improved current ripple; less amount of current ripple, higher
frequency and smaller torque pulsation
Basically, the 12 –pulse connection is a classical master-slave con-
figuration with a speed controlled 6-pulse master power converter
and a current controlled 6-pulse slave power converter. In addition
to these 2 identical power converters one field supply unit is
needed, which is controlled by the master.
The 12-pulse parallel connection is obtained by feeding the slave
with a mains supply offset by 30 degree compared to the master
and joining the power converter outputs on one side over a T-
reactor (interface choke, 12-pulse choke, … )
The 12-pulse mode has been implemented in the standard software
and will not become operative until parameterization is done. After a
few signals have been replaced for switch-on and switch-off, and
the specific master/slave parameters have been set, the two power
converters will work in the usual way. The only distinctive feature
compared with the classical 6-pulse version is that the two power
converters are synchronized for reversing the bridges.
Depending on the application and the type of converter (2 or 4
quadrant type) the final configuration is different:
- at 2 quadrant systems:
the 12-pulse function block remains unchanged; the current ref-
erence is taken out of the master and feed to the slave via ana-
log output – input;
see separate documentation MASTER – FOLLOWER 1.1
- at 4 quadrant systems:
the 12-pulse function block is used; the parameters need to be
set and the pins need to be connected;
see separate documentation DCS 500 Planning and Startup for
12 Pulse Power Converters
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