Kolloquiumsvortrag: Prof. Joachim Holtz, Life IEEE Fellow, University of Wuppertal / 19.10.15

19.10.2015 von 17:15 bis 18:45

Institut Elektrotechnik und Informationstechnik, Kaiserstr. 2, 24143 Kiel, Geb. D Raum: "Aquarium""

Titel: Reducing IGBT Switching Losses by Gate Charge Control

IGBTs are voltage controlled switching devices. Their fast switching characteristics
generate high voltage gradients which stress the motor winding insulation and generate
undesired bearing currents in ac drive systems. Electromagnetic interference may happen
with other electronic apparatus. Also the current gradients are high. They increase the diode
turn-off losses by generating high reverse recovery currents.
Voltage gradients are conventionally reduced by feeding the gate control signals through
resistors. The IGBT gate capacitance then delays the gate voltage changes, and thus increases
the transition intervals between switching states at the expense of higher switching losses.
The existing drawbacks are overcome by controlling the gate charge gradients at turn-on and
turn-off, thereby enforcing predetermined values of dv/dt and di/dt. Nonlinear dynamic IGBT
properties are accounted for. The gate charge profiles versus time are made dependent on the
particular load current value at switching, and on the internal device capacitances. These
incur rapid changes during the switching process under the influence of the device voltage
waveforms. Experiment results using 6.6 kV / 400 Amp IBGTs show that dv/dt is reduced
from 4 kV to 1 kV/ms while switching losses reduce to 70%.

About the Speaker
Joachim Holtz graduated in 1967 and received the Ph.D. degree in 1969 from the Technical
University Braunschweig, Germany.
In 1969 he became Associate Professor and, in 1971, Full Professor and Head of the Control
Engineering Laboratory, Indian Institute of Technology in Madras, India. He joined the
Siemens Research Laboratories in Erlangen, Germany, in 1972. From 1976 to 1998, he was
Professor and Head of the Electrical Machines and Drives Laboratory, Wuppertal University,
Germany. He is presently Professor Emeritus and a Consultant.
Dr. Holtz has extensively published, among others 12 invited papers in journals. He has
earned 15 Prize Paper Awards. He is the coauthor of seven books, and holds 33 patents.
Dr. Holtz is the recipient of the IEEE Industrial Electronics Society Dr. Eugene Mittelmann
Achievement Award, the IEEE Industrial Applications Society Outstanding Achievement
Award, the IEEE Power Electronics Society William E. Newell Field Award, the IEEE Third
Millennium Medal, the Anthony J. Hornfeck Service Award, and the IEEE Lamme Gold
Medal. He is a Life Fellow of the IEEE.
Dr. Holtz is Past Editor-in-Chief of the IEEE Transactions on Industrial Electronics, Distinguished
Lecturer of the IEEE Industrial Applications Society and IEEE Industrial Electronics

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