Principle Of Operation; System Perturbation - Siemens SINAMICS SL150 Operating Instructions Manual

3.3.3

Principle of operation

A special converter transformer suitable for operating a cycloconverter provides the supply
voltage from the medium-voltage system. Fans dissipate the heat losses. The current from the
snubber circuit supplies the CPLD electronics of the thyristors. Plastic fiber-optic conductors
transmit the gate signals from the PSA to the thyristor electronics board and the checkback
signals from the thyristor electronics to the PSA.
3.3.3.1

System perturbation

If the converter is connected to weak medium-voltage networks, filter circuits or a dynamic
reactive-power compensation system can be used to support the network. The required line
reactive power depends on the operating point (high reactive power with low speed and high
torque).
If you operate more than one cycloconverter at different speeds, the line current harmonics are
distributed across the frequency and are even partially eliminated.
Transvector control operates the synchronous machine with a motor cosϕ of approx. 0.95 to
1.0.
Figure 3-6
SINAMICS SL150 6SL38600UL432AA0Z
Operating Instructions Rev.201910281433 EXAMPLE
Typical line current harmonics of a 6-pulse cycloconverter
Description
3.3 Power unit
33