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a H-Bridge modulation strategy. It com-
bines both pulse-frequency and phase-
shift modulation improving the controlla-
ble voltage gain of a LLC-resonant circuit
by less frequency variation. Pulse patterns
are programmed directly on a flexible
FPGA platform acting as rapid prototyp-
ing system for our setups.
Various PFC and DC-AC circuits are con-
trolled by the same platform, including
a 4-quadrant operation of an H-Bridge.
Latter consists of Low-Side fast switching
MOSFET’s operating against SiC diodes,
and of 50Hz operated High-Side IGBT’s.
Magnetics
Inductive wireless-power systems for
consumer applications are analyzed with
special regard to the magnetic shielding
material. Furthermore, a 500W wireless
power transfer system was set up as part
of the 2015 IEEE International Future
Energy Challenge Competition.
A research project is on coupled induc-
tors with H-Bridge being supposed to
show material savings compared to clas-
sical inverter-legs with inductive output.
Such systems are analyzed in combi-
nation with the use of wide-bandgap
power semiconductor devices.
Drives / Electromobility
A novel drive train concept based on
the doubly rotating electrical machine
is demonstrated as depicted. It allows
a major increase in overall system effi-
ciency in contrast to conventional drive
train structures due to the connection
of electric powertrain, double rotating
electric motor and combustion engine,
optimized for a certain operating point
in terms of energy efficiency (2,9 l/100km,
calculated from internal, not calibrated
measurements of a 100km ride).
Cologne Institute for Renewable
Energy at Cologne University of
Applied Sciences
The Cologne Institute for Renewable Energy
(CIRE) is an association of currently 17 Pro-
fessors plus Scientists within the fields of
electrical engineering, mechanical engi-
neering and resource management.
With 17 disciplines under one roof, CIRE
combines interdisciplinary research and
teaching dedicated to the technology and
the implementation of renewable energy.
CIRE activities include a strong focus on
Power Electronics and Electrical Drives
with Prof. Lohner (Automation Engineer-
ing and Electrical Drives), Prof. Waffen-
schmidt (Electrical Grids) and Prof. Dick
(Power Electronics and Electrical Drives)
sharing laboratories, conducting research
and common publications.
Converter Modulation and control
Techniques
A research focus is on (resonant) DC-DC
converters, e.g. as maximum power point
tracker for PV. A major contribution was
Cologne Institute for Renewable Energy
