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Technische Universität Darmstadt
Description of research activities
The research activities of the Institute can
be grouped into two main areas:
1. Interaction between Power
Electronic Systems and Power Grid
Due to the success of Power Electronics –
enabled by the availability of powerful and
efficient semiconductors and expedited by
the extensive installation of renewable en-
ergies sources such as photovoltaics and
wind power – electrical energy has to un-
dergo a multitude of transformations by
means of power electronic systems dur-
ing the way from generation to consum-
er. Therefore, the characteristic of the grid
and the power quality (stability of voltage
level and frequency, harmonic content)
will be essentially influenced by Power
Electronic systems and components.
Therefore, emphasis has to be given to
the following aspects:
•
Active power filter and selective
harmonic cancellation
•
Optimizing of (passive) filter for active
infeed converter
•
Handling of unsymmetrical load
(occurrence of zero and negative
sequence)
•
Avoidance of unintended interaction
between power electronic systems
through the grid
•
Island operation and black-start
capability
2. Energy efficient drives
The efficiency of a drive system is deter-
mined by the electric machine and the
control methods implemented in the
frequency converter. Requirements for
efficiency of drives are described in the
European standard EN 50598 “Ecodesign
of Drives”.
Nowadays, predominately synchronous
or induction machine are being used
for drives. Alternatively, reluctance ma-
chines are under consideration in order
to achieve a better tradeoff between ef-
ficiency and costs. However, control of
reluctance machines including precise
control of torque and position over the
whole speed range is hard to implement,
especially if there is no room for the
application of position sensors for cost
and reliability reasons.
Our research is focused on the precise
torque and position control of reluctance
machine taking into consideration the
characteristics of the machine and the
frequency converter.
Lab Facilities
The lab AC power is supplied by 5 trans-
formers including voltage levels of 230V,
400V and 525V with a total power of
more than 1MVA. Additionally a DC grid
with up to 1.5kV and 192kW is available.
Teststand for an inverter with active neutral for
unbalanced power infeed
Institute staff in the lab facilities
2L-VSC SiC inverter with low common mode voltage
