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Awards – New topic, new presentation, new opportunity.

The PCIM Europe conference starts to the new season and again supports talents in the power electronics industry in 2019.

Where award-worthy ideas become award winners

Where award-worthy ideas become award winners

From all the papers presented, the conference directors select the ones to be honored at the opening event.

Apply for one of the three “Young Engineer Awards” if you are an engineer and not older than 35 years. Each prize is worth 1,000 Euro. The best submission overall will be honoured with the “Best Paper Award”. The winner will receive 1,000 Euro.

Award winners of PCIM Europe Conference 2018

The PCIM Europe conference committee led by Prof. Dr. Leo Lorenz, ECPE, Germany, chose this year’s winning entries from more than 340 papers that were submitted.

PCIM Europe 2018 Award winners
PCIM Europe 2018 Award winners (from left): Arne Hendrik Wienhausen, Alexander Lange, Thomas Fuchslueger, Fabian Denk.

Winner of Best Paper Award 2018

Arne Hendrik Wienhausen, RWTH Aachen, Germany
“Highly Integrated Two-Phase SiC Boost Converter with 3D Printed Fluid Coolers and 3D Printed Inductor Bobbins”

Arne Hendrik Wienhausen, RWTH Aachen, Germany

Short biography

Arne Hendrik Wienhausen (S’17) received his diploma degree in electrical engineering from RWTH Aachen University, Germany, in 2012. After his studies he joined the power electronics department of the Fraunhofer Institute for Solar Energy Systems ISE, Freiburg, Germany. Since 2016 he is with the Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, as a group leader of the power electronics group.

Title of the Paper

Highly Integrated Two-Phase SiC Boost Converter with 3D Printed Fluid Coolers and 3D Printed Inductor Bobbins

Summary of the paper

With the use of Selective Laser Melting (SLM) new 3D printed cooling structures for power converters can be realized. In this paper, a highly integrated two-phase interleaved bidirectional boost converter using discrete SiC-MOSFETs and 3D printed fluid coolers as well as 3D printed inductor bobbins is presented. The converter is operated at a high switching frequency of 400 kHz and features a high power density of 32.6 kW/dm3 while delivering 15 kW of output power.

Winners of Young Engineer Awards 2018

Fabian Denk, Karlsruher Institut für Technologie, Germany
“25 kW High Power Resonant Inverter Operating at 2.5 MHz based on SiC SMD Phase-Leg Modules”

Thomas Fuchslueger, Technische Universität Wien, Austria
“Reducing the dv/dt of Motor Inverters by a Two Leg Resonant Switching Cell”

Alexander Lange, Friedrich-Alexander-Universität Erlangen, Germany
„High Efficiency Three-Level Simplified Neutral Point Clamped (3LSNPC) Inverter with GaN-Si Hybrid Structure”

Fabian Denk, Karlsruhe Institute of Technology, Germany

Short biography

Fabian Denk received the M.Sc. degree in electrical engineering from the Karlsruhe Institute of Technology, Germany, in 2014. He is currently working at the Light Technology Institute of the Karlsruhe Institute of Technology, Germany. His research handle the characterization of silicon carbide power transistors and the development of high power resonant inverters operating in the MHz-range

Title of the paper

25 kW High Power Resonant Inverter Operating at 2.5 MHz with SiC SMD Phase-Leg Modules

Summary of the paper

In this work we present investigations on a high power resonant inverter operating at 2.5 MHz with ISOPLUS SMPD SiC-MOSFET phase-leg modules. These modules combine excellent thermal performance with very low parasitic inductances and good high frequency switching performance. A prototype of the full-bridge inverter with the SMPD module was built. With this prototype an efficiency of 95% was measured at a switching frequency of 2.5 MHz and an output power of maximal 25 kW could be delivered to the load resistor.

 

Thomas Fuchslueger, Technical University of Vienna, Austria

Short biography

Thomas Fuchslueger studied Electrical Engineering at TU Wien, Vienna Austria, with
focus on Automation Engineering/Power Electronics. He currently is working on the
research project for optimizing traction converter systems.

Title of the paper

Reducing the dv/dt of Motor Inverters by a Two Leg Resonant Switching Cell

Summary of the paper

A concept for reducing the output dv/dt of SiC PWM motor inverters, which keeps high semiconductor switching speed is presented and analyzed. This is achieved by
splitting up each phase leg into two legs which are gated slightly time delayed against each other and combining the output voltages by an interphase transformer. The stray inductance of this transformer in combination with an additional capacitor forms a resonant circuit which shows a cosine edge shaped output (motor) voltage at low dv/dt rates for a properly operation.

 

Alexander Lange, Friedrich-Alexander-Universität Erlangen, Germany

Short biography

Alexander Lange graduated in electronics engineering in 2015. Since 2015 he has
been with the Chair of Electrical Drives and Machines, University of Erlangen-
Nuremberg, Erlangen, Germany, where he is currently working towards his Ph.D.
degree. His main research interests include advanced control techniques for power
electronics and multilevel inverters for electrical drives.

Title of the paper

High Efficiency Three-Level Simplified Neutral Point Clamped (3L-SNPC) Inverter with GaN-Si Hybrid Structure

Summary of the paper

In this paper, a new Three-Level Simplified Neutral Point Clamped inverter with GaNSi hybrid structure for motor drive applications is introduced. This topology allows the utilization of fast switching capability of new wide bandgap power devices with low blocking voltage together with conventional silicon power devices with high blocking voltage in one system. Thus, the advantages of fast switching power devices and multilevel inverter topologies are combined and the efficiency can be improved.

Best Paper Award winners of recent years

Alexander Hensler, Siemens, Germany

Short biography

Alexander Hensler studied Electrical Engineering at the University of Applied Sciences in Nuremberg. He received his PhD degree from the Chemnitz University of Technology in 2012. Since 2011 he is working with Siemens AG, Business Unit Motion Control, in Erlangen. Currently he is developing new technologies for industrial inverter applications in the Innovation Center Power Electronics.

Title of the paper

Air Cooled SiC Three Level Inverter with High Power Density for Industrial Applications

Summary of the paper

A dual three phase three level converter has been realized with the newest generation of SiC MOSFETs, a space saving embedding technology of power semiconductors, an optimized air cooling concept and a novel DC link configuration. The air cooled converter system has a high power density of 17,2 kW/l combined with an efficiency of 99,2%. With the new inverter design the volume could be reduced by a factor of six in comparison to a standard high performance Si-based converter.

Nicolas Quentin, Sagem - Ampere Labs, France

Short biography

Nicolas Quentin received the Diploma degree in electrical engineering from ENSE3 University, Grenoble, France in 2013. He is currently pursuing the Ph.D. degree in electrical engineering at Safran Group and Ampere Lab. His research interests include topologies and control circuits on soft-switching power electronics converter.

Title of the paper

A Large Input Voltage Range 1 MHz Full Converter with 95% Peak Efficiency for Aircraft Applications

Summary of the paper

This digest presents a design methodology of a 50 W isolated DC/DC converter serving as a power supply for aircraft equipment like a FADEC (Full Authority Digital Electronics Control). The particularity of this work is the design of a full converter regarding two antagonistic requirements, which are wide input voltage and high efficiency.

 

Dorothea Werber, Infineon Technologies, Germany

Short biography

Dorothea Werber studied Electrical Engineering at the Technische Universität München, Germany, where she received the diploma degree in 2003. Hereafter she worked at the Institute for Physics of Electrotechnology at the Technische Universität München, Germany, on SiC bipolar diodes in the group of Prof. Dr. Gerhard Wachutka and received the Ph.D. in 2011. Since 2010 she has worked at Infineon Technologies AG in the field of IGBT chip and IGBT module development.

Title of the paper

A 1000A 6.5 kV Power Module Enabled by Reverse-Conducting Trench-IGBT-Technology

Summary of the paper

A reverse conducting IGBT module based on the well-established high insulation 6.5 kV-package platform for single switches is presented. The function of the IGBT-switch and the freewheeling diode is integrated into a single die enabling the higher current rating of 1000A by improved thermal resistance and dynamic loss reduction. Since the maximum allowed junction temperature remains at 125°C, no cutbacks of the power cycling reliability, yet an increase of the effectiveness are observed.

Martel Tsirinomeny, EPFL, Switzerland

Short biography

Martel Tsirinomeny received his Bac C in 2004. Then, he had followed the high school of engineering and got his diploma of electronics and industrial computing in 2010, from ESPA-Madagascar. Since 2011, he has been as a PhD student with the LEI-EPFL Lausanne, Switzerland. His main scientific interests include battery charging, hybrid and electric vehicles, modular multilevel converters as well as applications of modern control methods on power electronics systems.

Title of the paper

Configurable Modular Multilevel Converter (CMMC) for a Universal and Flexible Integrated Charging System

Summary of the paper

Electric Vehicles owners are confronted by the limited compatibility of available charging infrastructures. Therefore, this paper is focused on presenting a Configurable Modular Multilevel Converter (CMMC) for a universal and flexible integrated charging system. This concept is designed for a large range of charging infrastructure; from AC household basic supply to AC or DC ultrafast charging.

Eckart Hoene, Fraunhofer IZM, Germany

Short biography

Dr. Hoene was born in 1970. He studied drive engineering at the Technical University Berlin and entered Fraunhofer IZM in 1997. There we worked on his PhD on Predicting EMI behavior of drive systems, which he finished in 2001. After that he continued at the IZM as Postdoc, Gourp leader and finally business development manager. His group comprises 8 Scientists and his technical topics are EMC, Package development and system design. He holds 5 patents and is often invited speaker at conferences.

Title of the paper

Ultra-Low-Inductance Power Module for Fast Switching Semiconductors

Summary of the paper

The developments in switching semiconductors have come to a point, were the packaging of the semiconductors becomes a severe influence on switching performance. Especially wide  bandgap materials like SiC or GaN switch so fast, that parasitic influences of wire bonds or pins influence the components performance. Furthermore expert knowledge to design a switching cell properly in needed and inhibits the broad use of the superior semiconductor properties. In the paper “Ultra Low Inductance power module for Fast switching Semiconductors” new strategies and technologies presented to face this challenge. First of all a packaging technology was developed that combines a Direct Copper Bond (DCB) Substrate with Printed Circuit Board (PCB) technologies. Thereby the superior thermal properties of the ceramic is combined with the design freedom of the PCB. These possibilities were then used to create packages with extraordinary electromagnetic properties with the additional feature to be able to directly solder components like capacitors or drivers onto the module.

The manufactured module comprises a half bridge with SiC JFETs and a blocking voltage of 1200V. The Dc link inductance was measured to be below 1nH, which sets the new standard in packaging. The concept of the module is to integrate the critical switching cell into the module including a dc link capacitor. This module concept shows the way to make high speed switching available to users with less experience in design for high power and speed.

Keiji Okumura, ROHM, Japan

Short biography

Keiji Okumura studied in Nanomechanics and receved his Master degree from Tohoku University in 2007. Afterwards he joined ROHM Co., Ltd. as SiC power module engineer and got the R&D 100 awards in collaboration with Arkansas Power Electronics International, Inc., and the University of Arkansas, US in 2009. He is currently working on development and production of SiC MOSFET as SiC device engineer.

Title of the paper

Ultra low Ron SiC Trench devices

Summary of the paper

This paper presents next generation Silicon Carbide (SiC) planar MOSFETs, trench structure Schottky diodes, and trench MOSFETs. Firstly, some companies have already begun mass production of SiC planar MOSFETs for the sake of lower switching losses in high voltage applications such as converters and inverters. However, on-resistance increases when current flows into the parasitic body diodes of these mass-produced MOSFETs. This is because the parasitic PN body diodes, with the base plane dislocation, induce expansion of stacking faults in 4H-SiC epilayers and degrade the on-resistance of both the body diodes and MOSFETs. This is an obstacle for application in circuits which require current penetration from source to drain such as converters and inverters at the mass production level. However, our developed SiC planar MOSFETs have suppressed the degradation of parasitic PN junction diodes even if forward current penetrates into the PN junction diodes. Secondly, SiC Schottky diodes are attractive devices to reduce switching losses in high voltage applications. The reduction of conductive losses is also required to improve efficiency. However, SiC Schottky diodes have higher forward voltage drop when compared to silicon PN junction diodes. The reason is that SiC Schottky diodes need high barrier heights to block leakage current because SiC has a breakdown strength 10 times greater than that of silicon. SiC Schottky diodes, with newly developed trench structures, successfully showed lower forward voltage than conventional SiC diodes while keeping leakage current at an acceptable level. Thirdly, SiC trench MOSFETs can have lower conductive losses when compared with planar MOSFETs because planar MOSFETs have JFET regions which increase the on-resistance. However, the trench MOSFETs had issues regarding oxide breakdown at the trench bottom during high drain-source voltage application. Developed SiC MOSFETs with a double-trench structure have improved reliability of the device while maintaining ultra low on-resistance due to the fact that the new structure effectively reduced the highest electric field at the bottom of the gate trench, preventing gate oxide breakdown.

Sebastian Liebig, Liebherr-Elektronik, Germany

Short biography

Sebastian Liebig graduated from the University of Applied Sciences in Konstanz, Germany with german diploma degree in Electrical Engineering in 2007. Afterwards he joined Liebherr-Elektronik GmbH as power electronics engineer. Since 2010 Sebastian Liebig works on his PhD-thesis in the field of AC/DC topologies for aerospace applications. He graduates at the Technical University in Chemnitz, supervised by Josef Lutz, Chair of Powerelectronics and EMC.

Title of the paper

Concept and prototyping of an active mains filter for aerospace application

Summary of the paper

The requirements for high efficiency and low weight of subsystems in aerospace has led to increased research in power electronic devices. These play an important role in present and future airplanes. One major topic is the substitution of conventional hydraulic or pneumatic systems with electrical systems such as electrical environmental condition system (E-ECS). Conventionally, the DC-link voltage is generated using state-of-the-art topologies, most commonly active power factor correction (APFC) or autotransformer rectifier unit (ATRU). The active parallel power filter (APF) represents an interesting alternative to these topologies, since it has to be designed only for the sum of 5th and 7th harmonic power. This promises less weight and volume, which is a crucial topic for all aerospace systems. Due to high supply frequencies, which can vary between 360 and 800 Hz, the use of active filters in airplanes is more complex. The current control algorithm has to be robust and accurate during steady state condition . During frequency steps or ramps, the active filter must remain stable and follow with reasonable compensation performance but without faults or control loss. To ensure that both requirements are met, the control algorithm is split into two main parts - robust reference current generation based on instantaneous power theory and accurate harmonics regulation, which ensures the power quality. For the EMC design, the entire power electronic device is divided into several impedance matrices. The switching of active filter and motor inverter is translated into a voltage spectrum, which results together with impedance matrices in distortion currents. The influence of input and output filters can be calculated by simply adding another two matrices. These calculations are done using Matlab m-files. A power losses comparison between state-of-the-art 1200V NPT-IGBT and 1700V SiC-MOSFET reveals the superior properties of SiC-technology. In order to minimize the risk of a single-event burnout (SEB) induced by cosmic radiation, a 1700V MOSFET is chosen. The results of an APF prototype with smaller power rating are presented. The control is done with a rapid prototyping system from dSPACE. The 5th and 7th harmonics are compensated for to nearly zero percent. The dynamic behaviour during frequency steps and ramps is excellent. The deviation of 5th and 7th harmonics remains in a range of ±25% and does not cause any instabilities or loss of control. Further steps are the construction of a prototype with full power rating (46 kW) using SiC-MOSFET modules, the implementation of control algorithm into a DSP and validation of the proposed EMC filter.

Christian Nöding, University of Kassel, Germany

Short biography

Christian Nöding studied electrical Engineering and graduated from University of Kassel, Germany (Dipl.-Ing. M.Sc.) in 2009. Afterwards, he joined the Center of Competence for Distributed Electric Power Technology (KDEE) in Kassel, Germany. His main fields of interest are design and control of power converters for grid connection of decentralized energy sources as well as design of general energy converters.

Title of the paper

Evaluation of a Three‐Phase Two‐HF‐Switch PV Inverter with Thyristor‐Interface and Active Power Factor Control

Summary of the paper

For generators connected to the medium voltage grid new rules of action have to be applied in Germany since 2008. These new rules are defined within the medium voltage grid code of the BDWE, the “Bundesverband der Energie‐ und Wasserwirtschaft” and require special features of the generators which have an effect on cost of the devices especially when standard components are used (like IGBT). The presented PCIM‐paper deals with an inverter topology which combines the rugged properties of well known thyristors with functions of modern technology to comply with the requests of the grid code. Within this paper the “Minnesota Inverter” is evaluated, which was presented by Ned Mohan in 1995 for the first time. This topology uses only two high frequency switches to feed‐in a three‐phase sinusoidal current via a standard thyristor bridge. Thereby the power factor (cosφ) can be set within a specific range by a control strategy illustrated in this paper. Therefore a feed‐in of reactive power into the grid is possible which allows new ranges of application for thyristor topologies. Using modern SiC switches the “Minnesota Inverter” is able to utilize the full potential of  the SiC technology because of the high energy density within the high frequency switches. Next to a detailed description and control of the circuit the paper provides a comparison of the introduced topology to conventional circuits like 2‐level and 3‐level inverters. A table shows the field of application of the “Minnesota Inverter” in comparison to well known inverter topologies like 2‐level, NPC and BS‐NPC by using losses factors and the inductor volume. As a conclusion the results of a constructed prototype are presented. Scopes of the output signals at different power factors and a comparison of measured and calculated efficiency curves proves the operability of the system. Therefore the “Minnesota Inverter” presents an up to date alternative to common topologies due to the combination of cheap and rugged thyristors and modern high frequency switches like SiC switches.

Benjamin Sahan, University of Kassel, Germany

Short Biography

Benjamin Sahan was born in Hannover, Germany in 1979. He studied Electrical Engineering and graduated from Leibniz University of Hannover (Dipl.-Ing.) in 2006. Afterwards, he joined the Power Electronics Group at the Institute for Solar Energy Technology (ISET) in Kassel, Germany. He is also pursuing his PhD at the University of Kassel. His main fields of interest are design and control of power converters for grid connection of decentralized energy sources.

Title of the paper

Photovoltaic converter topologies suitable for SiC-JFETs

Summary of the paper

SiC semiconductors offer very interesting characteristics and can be considered as a future trend in photovoltaic converter technology. The vertical JFET is an example of a very promising device, mainly due to its relative structural simplicity. Nevertheless, its inherent normally-on characteristic calls for specially tailored topologies that has been presented and discussed in this publication. Finally, a 1kW laboratory prototype inverter was shown featuring very high efficiency using only one fast (SiC-JFET) switch which highlights the interesting potential for the future application of SiC-JFET devices in PV systems. The Centre of Competence for Distributed Power Technology (KDEE) has been founded in January 2009 at the University of Kassel. Focus is the research and development of electronic power conditioning units and systems for the exploitation of distributed, especially renewable, power resources. Beside scientific research KDEE is closely co-operating with industrial and utility companies.

Stéphane Lefebvre, SATIE, France

Short Biography

Stéphane Lefebvre received his Ph.D. degree in Electrical Engineering from the École
Normale Supérieure de Cachan, France, in 1994. He is currently working in the poxer
integration team of the SATIE (UMR CNRS 8029). He is professor at the Conservatoire
National des Arts et Métiers (CNAM), Paris, France, where he teaches Power Electronics.
He his currently interested in the behaviour of power semiconductor in hard working
conditions and at high operating temperature.

Title of the paper

Investigations on ageing of IGBT transistors under repetitive short-circuits operations

Summary of the paper

In this paper, we describe experimental results concerning the ageing of 600 V IGBT under repetitive short circuit conditions. A critical energy, which is dependant on test conditions, has been already pointed out which separates two failure modes. The first one, with a cumulative degradation effect, requires some 104 short circuits to reach failure and the other one leads to the failure at the first short-circuit with a thermal runaway effect. This paper is focused on the first failure mode. In order to characterize the electrical resistances of die metallization pad as well as contact between bond wires and metallization, Microsemi has realized a dedicated package. Several modules with 600 V IGBT dies (in Trench Field Stop technology) have been provided for this study. A four probe contact design was chosen for the bond wire connections (with judicious location of bond contacts) in order to perform precise measurement of the Al metallization layer and also of different electrical characteristics. Robustness results of IGBT transistors are presnted in the case of the repetition of short circuit operations in the ageing failure mode. The study is focused particularly on experimental results showing the correlation between the decrease of the short-circuit current and the increase of the on-state resistance. One hypothesis to explain these results is that some cells of IGBT dies may be disconnected from the Al metallization due to the strong degradation of this material. An other hypothesis is the transconductance variation due to the metallization degradation as well.Measurements allowed by Microsemi packaging have shown the effect of the repetition of short circuit operations on the increase of the resistivity of the Al layer. This is explained by Al reconstruction and cracks of the metal layer due to ageing. Strong degradation of the metallization (Al reconstruction and cracks) as well as bond wire lift offs were observed on all tested devices. In these specific conditions of test (dissipated energy lower than  the critical value), failure always appears at turn-off when the device begins to open the short circuit current which  looks like dynamic latchup. The local increase of temperature due to wire contact degradation and Al layer ageing when repeating short-circuit could explain the failure at turnoff considering the trigger of the parasitic transistor of the IGBT which is facilitated by the temperature rise. In order to understand this phenomenon, the next step will be to verify the hypothesis given above. For this purpose, we plan to study the effect of the metallization ageing on the transconductance and thus on the gate drive characteristics. In addition, we will characterize the rate of disconnected IGBT elementary cells from the metallization layer (contact quality).This will be made by failure analysis techniques like micro-sections.

Young Engineer Award winners of recent years

Marco Denk, University of Bayreuth, Germany

Short biography

Marco Denk received his Master's degree in 'Electrical Engineering' in 2012 and his Ph.D. in 'Power Electronics' in 2016. Currently he is post-doc at the University of Bayreuth. His areas of interest include junction temperature measurement and innovative gate driver circuits.

Title of the paper

IGBT Gate Driver with Accurate Measurement of Junction Temperature and Inverter Output Current

Summary of the paper

This paper presents an advanced IGBT gate driver that includes a combined measurement of the IGBT junction temperature and the inverter output current. For this purpose, the conventional gate driver is expanded by two simple measuring circuits that determine the collector-emitter voltage and the on-chip internal gate resistor of the IGBT during the regular inverter operation. This combination of two different temperature sensitive electrical parameters enables accurate temperature and current measurement on driver level.

 

Tomoyuki Miyoshi, Hitachi, Japan

Short biography

Tomoyuki Miyoshi received the B.S., M.S., and Ph.D. in Tohoku University, Miyagi,Japan, in 2005, 2007, and 2015. In 2007, he joined Hitachi, Ltd., Japan. He is currently engaged in research and development of power device technologies.

Title of the paper

Dual Side-Gate HiGT Breaking Through the Limitation of IGBT Loss Reduction

Summary of the paper

A novel Dual side-gate HiGT (High-conductivity IGBT) with an extremely small feedback capacitance (Cres) and a function of controllable conductivity modulation was proposed. Dynamic control of stored carrier concentration right before switching  by tandem drive of the dual gate makes it possible to further reduce switching loss with conventional single-gate IGBTs. Compared to the single gate drive, dual side-gate HiGT further reduces loss during turn-on and turn-off by 12% and 30%, respectively.

 

Franz Stubenrauch, University of Applied Sciences Rosenheim, Germany

Short biography

Study of Electrical Engineering and Information Technology at University of Applied Sciences Rosenheim, Germany. Ph.D. student at Technische Universität München and University of Applied Sciences Rosenheim. Topics of Bachelor and Master Thesis in power electronics with the focus on resonant topologies and high switching frequencies. Employment as Ph.D. student since 2014 with the focus on high switching frequency converters at University of Applied Sciences Rosenheim, Germany.

Title of the paper

Design and Performance of a 200 kHz GaN Motor Inverter with Sine Wave Filte

Summary of the paper

This paper analyses Gallium Nitride semiconductor devices as an alternative for future motor inverters. Due to the small switching loss the PWM frequency range can be extended up to 500 kHz. This allows the use of motor filters with small component size. As a result, high motor efficiency, low torque ripple, high control bandwidth and nearly ideal sinusoidal output voltages are achieved. A hybrid sine wave filter consisting of an analog and a digital part is presented and optimized to achieve low power loss and high current control bandwidth. A 3-phase GaN motor inverter with 200 kHz PWM frequency verifies the system design.

Christian Felgemacher, University of Kassel, Germany

Short biography

Christian Felgemacher received the M.Eng. (Hons.) degree in electronics and electrical engineering with management from the University of Edinburgh, Edinburgh, UK in 2011. He joined the Centre of Competence for Distributed Electric Power Technology at the University of Kassel in 2012.

Title of the paper

Benefits of Increased Cosmic Radiation Robustness of SiC Semiconductors in large Power-Converters

Summary of the paper

Cosmic radiation induced single-event-burnout is a known failure mode for power semiconductors. To achieve high reliability derating of the maximum voltage applied to the semiconductors is common. Measurements of the voltage dependent failure rate of SiC MOSFETs have shown that SiC devices can be operated with less voltage derating. The possible advantage this brings for applications such as photovoltaic inverters is investigated in this paper.

 

Stefan Hain, University of Bayreuth, Germany

Short biography

Stefan Hain studied physics at the University of Bayreuth and got his diploma in 2011. Since then he works as an academic council at the department of mechatronics at the University of Bayreuth. His research area includes the characterization of extremely fast switching IGBTs, the development of fast short circuit detection methods and new current measurement technologies.

Title of the paper

New Ultra Fast Short Circuit Detection Method Without Using the Desaturation Process of the Power Semiconductor

Summary of the paper

This paper presents a new short circuit detection method for power semiconductor devices by monitoring the di/dt and gate voltage behaviour. It can be shown that this method is able to detect a low inductive hard switching fault within 20ns, after the fault can be  distinguished from a normal turn-on process. Furthermore, the ability to detect fault under load conditions reliably with low and high short circuit inductances is demonstrated.

 

Christoph Marxgut, Helbling Technik, Germany

Short biography

Christoph Marxgut received the M.Sc. degree (with Hons.) from the University of Technology Vienna, Austria, in 2008, and the Ph.D. degree from the Power Electronic Systems Laboratory (PES), ETH Zürich, Switzerland, in 2013. He is currently working with Helbling Technik as a power electronic specialist focusing in renewable energy and automotive systems.

Title of the paper

A Generic Topology for Electrical Energy Storage Systems

Summary of the paper

This paper presents an electrical storage system which is aimed for the recuperation of energy in electrical drives. The topology is based on a combination of a multi-level and a bidirectional boost converter which enable the application of low-voltage energy storage components. Due to its generic structure, the topology can be adapted to different voltage, power, and energy levels which makes it interesting for various applications.

Marinus Petersen, University of Kiel, Germany

Short biography

Marinus Petersen received the Dipl.-Wirtsch.-Ing. degree in 2012 from the Christian-Albrechts-University of Kiel, Germany, where he is currently a Research Assistant in the Institute for Power Electronics. His current research interest lies in the area of E-Mobility with focus on contactless charging techniques.

Title of the paper

Design of a Highly Efficient Inductive Power Transfer (IPT) System for Low Voltage Applications

Summary of the paper

Design variants for SS-compensated IPT systems in low voltage applications (<100 V) are investigated. The analysis in this paper is focused on the optimal power electronics and system topology. The validity of the results is exemplarily shown on a 6 kW prototype with an input voltage of 400 VDC and low output voltage of 24 VDC (battery voltage). A high efficiency between 90.1 and 94.2 % can be achieved in any operation point.

 

Jan Richter, Karlsruhe Institute of Technology, Germany

Short biography

Jan Richter graduated from Karlsruhe Institute of Technology (KIT) with his diploma in 2011.  In June 2011 he started to work as a doctoral candidate at the Institute of Electrical Engineering at KIT in the field of modelling, parameter identification and control of permanent magnet synchronous machines with nonlinear magnetics.

Title of the paper

Mitigation of Current Harmonics in Inverter-Fed Permanent Magnet Synchronous Machines with Nonlinear Magnetics

Summary of the paper

Inverter nonlinearities and machine spatial harmonics yield unwanted machine current  harmonics causing additional losses and torque ripples. Thus, a method is presented that  allows online identification and compensation of both effects for permanent magnet synchronous machines with nonlinear magnetics. The method does not require additional sensor signals and can be implemented easily in existing inverters. Test bench measurements show significant improvements in the whole operational area. Using the proposed method, the total harmonic distortion of the motor current can be reduced to less than an eighth of the uncompensated value at nominal operation for the machine under test.

 

André Schön, University of Bayreuth, Germany

Short biography

André Schön received his diploma degree in Electrical Engineering from the University of Erlangen-Nuremberg in 2011. In 2012 he joined the Department of Mechatronics at the University of Bayreuth and is currently working towards his PhD. His research interests include power electronics for HVDC transmission systems, especially high power DC/DC converter, power flow control and grid stability.

Title of the paper

Comparison of the most efficient DC-DC Converters for Power Conversion in HVDC Grids

Summary of the paper

The structure of electric energy generation is rapidly changing, from controllable and equally distributed power generation using few high power plants to a decentralized power generation with many, widely distributed power plants. The key technology for the future of the power grid is HVDC power transmission, which will move from the periphery of the AC grid to its center. In this paper two promising HVDC-DC converter topologies will be compared in terms of efficiency and investment costs.

Vinoth Kumar Sundaramoorthy, ABB Switzerland, Switzerland

Short biography

Dr. Sundaramoorthy is working as a Scientist at Corporate Research Center of ABB Switzerland Ltd, Switzerland since August 2008. He completed his PhD in Electrical Engineering from University of Nottingham, UK in 2008. His research interests include design and characterization of silicon and wide  bandgap semiconductor devices for power electronic applications.

Title of the paper

Simultaneous Online Estimation of Junction Temperature and Current of IGBTs Using Emitter-Auxiliary Emitter Parasitic Inductance

Summary of the paper

A novel method is presented for online estimation of the junction temperature (Tj) of semiconductor chips in IGBT modules, based on the voltage drop (VEE`) across the parasitic inductor that exists between the main emitter (E) and auxiliary emitter (E`) terminals. The peak amplitude of the voltage drop (VEE`) was found to depend on the junction temperature at a known current and DC link voltage. Also, the collector current can be estimated simultaneously, by integrating VEE without the use of any additional sensors. Measurement circuits were implemented to estimate Tj and the current, and their results are discussed.

 

Hidekazu Umeda, Panasonic, Japan

Short biography

Hidekazu Umeda received the B.S. and M.S. degrees in electrical engineering from Osaka University, Osaka, Japan, in 2004 and 2006, respectively. In 2006, he joined Semiconductor Device Research Center, Panasonic Co. Ltd., Osaka, Japan. His current interests include GaN-based electronic devices for  power switching and high frequency applications.

Title of the paper

Highly Efficient Low-Voltage DC-DC Converter at 2-5 MHz with High Operating Current Using GaN Gate Injection Transistors

Summary of the paper

A low-voltage DC-DC converter using GaN Gate Injection Transistors (GITs) demonstrates highly efficient operation at 2-5MHz with high output current. Reduction of the gate lengths of the GITs and optimized design of the field plates significantly improve the RonQg down to 19mOnC. The peak efficiency at  2MHz reaches 90% for the conversion from 12V to 1.2V, while the operating current can be increased up to 50A. The converter also can serve 5MHz operation with the peak efficiency of 81%.

 

Gang Yang, Valeo, France

Short biography

Gang Yang received Dipl-Ing and PhD degrees in Electrical Engineering both from SUPELEC, France, 2010 and 2014 separately. Since 2010, he has been with VALEO as a power electronics engineer, where he was involved in the research and development of high efficiency power converters for electric/hybrid vehicles. He is currently a senior power electronics engineer at VALEO, France. Untill now, he has authored more than 20 referred papers and held 3 patents. His fileds of interest are in the area of power electronics.

Title of the paper

High Efficiency Parallel-Parallel Interleaved LLC Resonant Converter for HV/LV Conversion in Electric/Hybrid Vehicles

Summary of the paper

A hybrid/electric automobile targeted 2.5kW, 250 kHz, HV/LV double phase parallelparallel LLC resonant converter is presented. A double loop control strategy is proposed to share the current equally between the two power cells and to maintain a high efficiency among a wide power range. The total  prototype performs 3kg, 2.5L, with a nominal efficiency higher than 94% and a power density 1W/cm3.

Samuel Araújo, University of Kassel, Germany

Short biography

Samuel Araújo received the Bachelor in Electrical Engineering in the Federal University of Ceará in Brazil and the Master of Science in Renewable Energies and Energy Efficiency (RE2) at the University of Kassel in Germany. He is now pursuing his PhD at the University of Kassel under the supervision of Prof.  Peter Zacharias. He is currently working as the leader of the Power Electronics group from the Centre of Competence for Distributed Electric Power Technology at the Kassel University.

Title of the paper

High Switching Speeds and Loss Reduction: Prospects with Si, SiC and GaN and Limitations at Device, Packing and Application Level

Summary of the paper

The prospect of increasing the switching frequency without sacrificing efficiency is seen in many fields of application as a promising development. This will be mainly achieved through new device technologies, not only relying on WBG materials but also on silicon, capable of operating at much faster switching speeds and thus with lower losses. On the other hand, new developments in the field of packing and montage are necessary in order to fully exploit new device capabilities.

 

Radoslava Mitova, Schneider Electric, France

Short biography

Dr. Radoslava Mitova received M.S degree in Electric Engineering from the Technical University of Sofia in 2001 and Ph.D degree in Power electronics from the National Polytechnic Institute of Grenoble in 2005. She also worked for PRIMES Lab (Tarbes) on high voltage architectures with medium voltage transformer for railway traction. She joined Schneider Electric in 2007 as power electronic engineer. She is currently working on new material power semiconductors as SiC and GaN in industrial application inverters.

Title of the paper

Half Bridge Inverter with 600 V GaN Power Switches

Summary of the paper

The emerging GaN power devices promise to outperform the actual Silicon devices and to challenge the Silicon Carbide ones in 600 voltage range thanks to their faster switching speed. This article presents evaluation of new GaN transistor devices in half- bridge inverter. The operation principle of these devices in half-bridge configuration is be detailed. Multiple measurements carried out on a dedicated test bench will show the performances of the GaN devices.

 

Daniel Wigger, University of Rostock, Germany

Short biography

Daniel Wigger studied electrical engineering at the University of Rostock and got his diploma in 2007. Since 2008 he works as a research assistant at the University of Rostock. His technical interests include the application and the device physics of high voltage power semiconductors.

Title of the paper

Impact of Inhomogeneous Current Distribution on the Turn-off Behavior of BIGTs

Summary of the paper

The BIGT shows a soft turn-off behavior in the IGBT-mode. A reason for the soft behavior is the dynamic avalanche, which limits the dvCE/dt and the electric field in the device. In comparison to IGBT with the same current density, the dynamic avalanche inception voltage of BIGT is significantly lower. This is caused by an inhomogenous current distribution inside the BIGT, which leads to a higher hole density in regions with higher current and thereby to a higher gradient of the electrical field. In this paper the influence of the current distribution on the turn-off behavior will be described.

Johannes Kolb, Karlsruhe Institute of Technology (KIT), Germany

Short biography

Dipl.-Ing. Johannes Kolb received the Dipl.-Ing. degree from the University of Karlsruhe (TH), Germany in 2007. Since that time he has been working as scientist at the Institute of Electrical Engineering which is located in the Karlsruhe Institute of Technology (KIT) to receive a PhD. His research interests are Electrical Drives and Power Electronics especially Multilevel converters and novel converter topologies.

Title of the paper

Operating performance of Modular Multilevel Converters in drive applications
Summary

Summary of the paper

This paper presents an investigation on Modular Multilevel Converters used as motor-sided converter as well as grid-sided active-front-end converter. Experimental results from a prototype system show the operating performance of the DC-coupled MMCs at steady state including the start-up procedure. The MMC can be run up by pre-charging the cells via resistors, where no extra, galvanic isolated feed-in with an additional voltage source is necessary. The dynamic response of the system is tested to verify the cascaded vector control scheme of the MMCs. The measurements from the low voltage MMC  system illustrate the proper operation of the Modular Multilevel Converter. The suitability of the control system for balancing the inner energy in the capacitors of the arms is verified under all operating conditions. It is shown that this control scheme is qualified for an operation of several, DCcoupled MMCs.  Finally, the control scheme can be transferred to medium and high voltage applications without any difficulty.

 

Hari Babu Kotte, Mid Sweden University, Sweden

Short biography

Hari Babu Kotte received his B.Tech (EEE), M.Tech in Power Engineering from JNTU, Hyderabad, India. He has also received his M.S and Licentiate degrees (M.Phil) in Power Electronics from Mid Sweden University, Sundsvall, Sweden and currently working towards his PhD on ‘High Speed Switch Mode Power Supplies’. His research area includes high speed DC/DC, AC/DC converters, resonant converters, power semiconductor devices, PCB transformer technology.

Title of the paper

A ZVS Half Bridge DC-DC Converter in MHz Frequency Region using Novel Hybrid Power Transformer

Summary of the paper

The significant problems in increasing the switching frequency of isolated converters to achieve low cost and high power density are increased magnetic and switching losses. This paper presents solution with the investigation of newly designed high frequency, low profile, hybrid power transformer  together with commercially available GaN MOSFETs. For achieving stringent power converters, a center tapped 4:1:1 half bridge transformer was designed in a multilayered PCB laminate with a total height of transformer as 4.2mm. The maximum obtained energy efficiency of transformer is 98% in the frequency region of 1 – 5MHz with tested power density of 47W/cm3 at an operating frequency of 3MHz. This transformer has been utilized in the multi resonant zero voltage switching (ZVS) half bridge converter with synchronous rectification using GaN MOSFETs and then evaluated. The maximum achieved efficiency of the converter with this transformer is 92% in 3 – 4.5 MHz switching frequency range with characterized output power of 40W. This work provides considerable step for the development of next generation ultra flat low profile isolated DCDC/AC-DC converters operating in MHz frequency region.

 

Marek Siatkowski, University of Bremen, Germany

Short biography

Marek Siatkowski received Dipl.-Ing. Degree in Electrical Engineering from the University of Bremen, Germany in 2006. Subsequently, he joined the Institute for Electrical Drives, Power Electronics and Devices (IALB), at the University of Bremen. He is working towards his Dr.-Ing. degree. His main research fields include numerical (FEM) analysis of electromagnetic fields and electrical machine design, especially Transverse Flux and permanent magnet machines.

Title of the paper

Construction of a High Force Density Linear Motor with a Passive Stator using Transverse Flux Technology

Summary of the paper

In most direct drive linear motors high energy permanent magnets are used in the stator, which makes the stator length a significant cost factor.The IALB has developedand builta synchronous permanent magnet linear motor with a passive, and therefore cost effective, stator. Theexcitation magnets and  phase windings are located in the short mover. High thrust force densities were reached, which are comparable to other which are comparable to other high end linear direct drives on the market..

Johannes Kolb, Karlsruhe Institute of Technology (KIT), Germany

Short biography

Dipl.-Ing. Johannes Kolb received the Dipl.-Ing. degree from the University of Karlsruhe (TH), Germany in 2007. Since that time he has been working as scientist at the Institute of Electrical Engineering which is located in the Karlsruhe Institute of Technology (KIT) to receive a PhD. His research interests are  Electrical Drives and Power Electronics especially Multilevel converters and novel converter topologies.

Title of the paper

A novel control scheme for low frequency operation of the Modular Multilevel Converter

Summary of the paper

The contribution presents a control strategy for the Modular Multilevel Converter (MMC), which allows generating low frequency or even zero frequency three-phase output voltages. This feature is necessary to feed a three-phase machine at low frequency. The common mode voltage and correspondent  inner currents are used to ensure a symmetrical energy distribution in the arms of the MMC and to avoid AC-currents in the DC-source.

 

Anna Mayer, University of the federal armed forces Munich, Germany

Short biography

Anna Mayer received the Dipl.-Ing. (M.Sc.) degree in 2008 from the “Universität der Bundeswehr München”, Munich. She is currently working toward the Ph.D. degree in Power Electronics at the “Universität der Bundeswehr München”, Munich, Germany in the Institute for Power Electronics and Control. She is engaged in research and control of new converter Topologies.

Title of the paper

Control Concept of the Modular High Frequency – Converter for Vehicle Applications

Summary of the paper

For future vehicles, new converter systems are required. Beside low weight and a small volume, low losses and an excellent dynamic behavior are demanded. These requirements cannot be met with conventional converters like 2-level IGBT-converters or NPCs. The new Modular High Frequency-Converter  MHF) for vehicle applications enables essential improvements of these problems. This paper presents a control concept of the MHF. Moreover test results of the excellent dynamic behavior are depicted.

 

Hitoshi Uemura, Mitsubishi Electric Corporation, Japan

Short biography

Hitoshi Uemura received the B.E. and M.E. degrees in applied Electrical Engineering from University of Nagasaki in 2003 and 2005. In 2005, he joined the Power Device Works of Mitsubishi Electric Corporation, where he works on the High Voltage design & development Dept.  

Title of the paper

Optimized Design Against Cosmic Ray Failure for HVIGBT Modules

Summary of the paper

The new developed HVIGBT (High Voltage Insulated Gate Bipolar Transistor) has been improved the robustness against cosmic ray induc ed failure in comparison with conventional IGBT. The key factors are the distribution of electric field strength by LPT structure with optimized carrier lifetime control and  minimized the crystal defect in silicon by the strengthened gettering during of wafer process. Consequently the SEB failure spot moved from the collector side to emitter side prov ed by the analysis of the neutron irradiation experiment and investigation of failed HVIGBT chips. The new developed HVIGBT also decreased power losses and decreased leakage current.

Dayana El Hage, EPFL, Switzerland

Short biography

Finished studies in electrical engineering in Lebanon (Ecole supérieure d'ingénieurs de Beyrouth) in 2007 and did Master degree in Ecole Polytechnique Fédérale de Lausanne (EPFL) in Electricity and Electronics (power conversion and systems). Finished in february 2009 and continued working in
EPFL in the Industrial Electronics Laboratory (LEI). Did internships both in Lebanon (Matelec, Ghorfine) and in Switzerland (Ecole d'ingénieurs et d'architectes de Fribourg and Pasan S.A. Neuchâtel).

Title of the paper

A High Current Pulse-Power Supply for Flash Lamps in PV-Panel Measurement-Facilities

Summary of the paper

In this paper, a high current pulse power supply for the feeding of a flash lamp has been developed, on the base of a multilevel converter with cascaded cells. The pulsed high power is provided by capacitive energy storage, directly connected to the cells of the converter. A low current ripple is reached by  interleaved switching technique. The original topology, its design regarding the sizing of the storage cells, and the associated control are presented. Simulation results as well as a realization of a prototype for industrial use are described in details.

 

Christoph Klarenbach, University of Applied Sciences Cologne, Germany

Short biography

Christoph Klarenbach studied electrical engineering from 2001 to 2006 at Wuppertal University where he became a Master of Science in 2006. He focuses on the areas of control and drive technology as well as power electronics. He is currently working on his doctoral thesis in the field of drive control using FPGAs. This research project is sponsored by Beckhoff Automation, Germany.

Title of the paper

Fast and High Precision Motor Control for High Performance Servo Drives

Summary of the paper

This paper reports a new architecture of a fast current controller with two feedback signals for high performance motion control. Due to parallel processing inside the Field Programmable Gate Array (FPGA), the control algorithm computing time is significantly less than 1 μs. Together with advanced control  technologies in combination with a new current observer the bandwidth of fast switching IGBT or MOSFET power stages is not limited by the delay time of high precision (integrating) current measurement any longer. Using that technology high control bandwidth in conjunction with high precision current control is now possible at no trade off. The control strategy relies on a simplified machine model without incurring performance degradations. The presented results have been produced with a high speed Computerized Numerical Controlled (CNC) machine (high speed lathe).

 

Andreas Munding, Liebherr Elektronik, Germany

Short biography

Andreas Munding graduated from the University of Ulm in Ulm, Germany with a german diploma degree in Electrical Engineering in 2002. He has worked as a researcher in the field of 3D chip integration at the University of Ulm and at Vestfold University College in Horten, Norway. In 2007 he received his doctoral degree in engineering from the University of Ulm. Dr. Munding is working for Liebherr-Elektronik GmbH since 2007, where he is a project leader in the department of advance developement.

Title of the paper

Compact PCB-packaging and water cooling of a 25-kW inverter

Summary of the paper

In many power electronics applications, volume and weight is a cost factor which developers seek to minimize by increasing power density. Many approaches to achieve a higher power density focus on reducing wiring and tubing expenses by integrating the system components into the electric actuator. The resulting installation areas are typically exposed to high vibrational and high temperature stresses. This work features simulation results of a sandwich PCB assembly with an electronic board and a high current board attached to either side of an aluminum heat sink. This heat sink is thermally attached to the metal housing and to a liquid cooling channel which was optimized for low pressure drop. In addition, the effect of the low pressure drop cooler structure on the IGBTs of a directly cooled pin-fin based power module was simulated and characterized. It was found that a geometry with lateral coolant  impingement exhibit lowest pressure drop and allows for a large flow rate operation range in automotive applications.

Michael Heeb, University of Kassel, Germany

Short biography

Michael Heeb holds a technical degree (Dipl.-Ing.) of Technical University of Ilmenau. He carried out research on MOSFET switching and EMC tests. Since 2006 he has been with the Institute of Electric Power Supply Systems at the University of Kassel. Here, he is researching on oscillations in high power  semiconductors.

Title of the paper

Carrier Transit Time Approximation for Prediction of PETT Oscillation in Power Diodes

Summary of the paper

Plasma Extraction Transit Time (PETT) Oscillation can appear under special conditions during the turn-off phase of high power semiconductors. It can be suppressed or supported by the circuit arrangement given by the module layout incorporating the chips. PETT is a high frequency oscillation which  possibly spreads out into the close vicinity of the device and thus can cause EMC disturbances. The frequency range of the oscillation can be estimated by simple analytical formulas reported in the literature or sophisticated numerical analyses. Several measures for PETT avoidance are also reported. In the present work a new analytical procedure for predicting the frequency range of PETT Oscillation is presented and compared to experimental findings. Together with the simulation of the parasitic environment a sufficient match between theory and experiment is achieved. These results can be implemented in the design flow for power semiconductors and thus improve the quality and reliability.

 

Jérémy Martin, PEARL-ALSTOM Transport, France

Short biography

Jérémy Martin received the Postgraduate degree in electrical engineering from Université de Montpellier II, Montpellier, France, in 2006. He is currently working toward the Ph.D. degree that focuses on high-power converters for railway traction. ALSTOM Transport P.E.A.R.L, SEMEAC, France. Laboratoire Plasma et Conversion d’Energie, Toulouse, France.

Title of the paper

Characterisation of IGBTs in Soft Commutation Mode for Medium Frequency Transformer Application in Railway Traction

Summary of the paper

Nowadays, the typical railway traction chain, which operates under AC catenaries, includes a bulky and heavy transformer. In order to reduce the weight and the size of the input transformer, a medium frequency topology, which involves soft commutation mode for the switches, is proposed. At this effect, for the characterization of high voltage components in soft commutation mode, a specific test bench is built in the Power Electronics Associated Research Laboratory (PEARL, Tarbes , France). In this paper, experimental characterisation results are given for 6.5 kV IGBTs in Dual-Thyristor mode. The snubber  capacitors provide a significant reduction in turn-off energy and a switching frequency of several kHz is then possible.

 

Roland Zeichfüßl, Siemens AG, Germany

Short biography

Roland Zeichfüßl received the Dipl. Ing. degree in electrical engineering from the Technical University Munich, Germany, in 2007 and is currently working towards the doctorate degree at the Technical University Munich. In 2007 he received the Ernst von Siemens Doctoral scholarship, which supports alented young scientists in their doctorate projects. His research focuses on switched-mode power stages and motor control on the hardware description level for the piezoelectric actuator drives.

Title of the paper

A Powerful and Efficient Switch-Mode Power Stage for a New Piezoelectric Drive

Summary of the paper

The Piezoelectric Actuator Drive (PAD) is a highly dynamic and powerful rotary motor with high angular resolution. Its kinematic principle converts the periodic linear motion of solidstate actuators into a continuous and precisely controllable rotation. In comparison to conventional positioning drives it  does not require gears, brakes or rotary encoders. The PAD is driven by powerful piezoelectric multilayer stacks, which electronically behave like capacitors. Thus it requires an efficient power stage, which recovers the energy stored in the actuators, to attain high mechanical output power and low losses at  the same time. Furthermore high signal quality is essential for high positioning accuracy and low noise during operation. At the beginning an appropriate topology and filter is selected. It is then analyzed by calculation and simulation. After dimensioning the parts, the signal quality is estimated. Finally the power, efficiency, and real signal quality are experimentally evaluated by driving the PAD in a motor test bench at high speeds and loads.

Marco Bock, Siemens AG, Germany

Short biography

Marco Bock, a 27 years old doctoral student in mathematics at the Justus-Liebig-University (JLU) in Gießen, is writing his doctoral thesis at the Siemens company (Automation and Drives, Motion Control, Research and Development) since January 2007. The topic is 'Time Optimal Motion Planing for  Redundant CNC-Axes'. From 2001 to 2006 he studied mathematics/computer science at JLU Gießen where he got his diploma. The focus of his diploma thesis was applied mathematics.

Title of the paper

Methods for Path Decomposition of Redundant CNC-Axes and large working range with redundant axes

Summary of the paper

This approach consists of a conventional large machine with a high working volume, but at the position of the tool center point an additional lightweight, highly dynamic, small machine is installed. It can be seen as a ”machine inside a machine”. In 1992 this concept was already patented for machine tools,  but it did not gain much attention since the computing power necessary for the control algorithms was not yet available. Today, the situation has changed: Research activities on corresponding control algorithms have been started, and several manufacturers already offer redundant machines. To combine the individual advantages of both parts, special control strategies inside the CNC are necessary. While the machine is in action, all axes should move coordinated and synchronously, and so the motion of the tool center point is composed of a part for the large machine and a part for the small machine. Therefore, the question is: How to decompose the motion to obtain high productivity. The paper focuses on two geometric methods to compute such a decomposition. All geometric paths in the paper are represented by so-called spline curves. A decomposition method in the sense of the paper is an  algorithm which computes for both, the large and the small machine, an individual spline curve as its reference path. Two conditions are crucial: The sum of both paths has to result in the path for the tool center point and all axes have to stay within their working range. The methods themselves use techniques from mathematical approximation theory. In the first one a spline operator (Schoenberg operator) is applied. In the second approach the path for the large machine is determined as a spline curve which minimizes a certain smoothing functional under constraints. This leads to an optimization  problem with a quadratic objective function and linear constraints. Both methods can be realized inside the numerical control kernel. Finally, the developed methods have been tested by simulation. It turns out that the productivity of a machine with redundant axes is higher than that of a non-redundant machine with the same working range. Furthermore, the optimization approach results in shorter machining times than the first one but also needs more computing power.

 

Luc Lowinsky, LAPLACE Research Laboratory, France

Short biography

Luc Lowinsky was born in Saint-Denis de la Réunion, Reunion Island, France, in 1981. He  received the M.S. degree in power electronics in 2006 from the University Paul Sabatier in Toulouse, France. He joined the Société Nationale des Chemins de Fers (SNCF) and the Laboratoire des PLAsmas et de  Conversion d'Energie (LAPLACE), in Toulouse, France, as a Ph D student. His Ph D subject concerns the reactive power compensation in AC railway network.

Title of the paper

3 MVAR Single Phase STATCOM based on AC Chopper Topology

Summary of the paper

25 kV AC single phase supply is widely used in railway systems in France. The use of such systems require the installation of reactive power compensators (as traffic and load increase) to reduce the spending for reactive power and to keep the voltage at acceptable level. Nowadays, the 25 kV AC single  phase network of the SNCF is equipped with thyristor based Static Var Compensators SVC. The main disadvantage of this topology is the requirement of a large LC shunt filter tuned for the third harmonic. That is why the SNCF is prospecting for new high efficiency topologies using PWM control. Compared  to a Voltage Source Inverter, the AC Chopper topology which allows reducing the commutation losses was selected. The AC chopper STATCOM presented in this paper is based on low voltage IGCTs. The single phase STATCOM system is rated for 3 MVAR and three modules, providing 1 MVAR, are parallel  associated and interleaved. The semiconductor losses are evaluated by two methods .The first one is based on analytic relationships obtained by calculation. The second one consists of a power losses estimator included in the simulation circuit of the STATCOM. Finally, to demonstrate the feasibility of this  solution and to validate the current control loop, experimental results, concerning a 100 kVAR single-phase AC Chopper, are presented.

 

Matthias Neumeister, Siemens AG, Germany

Short biography

Matthias Neumeister was born in Löbau, Germany, in 1975. From 1992 till 1997 he passed an apprenticeship as electrician. From 2000 till 2002 he successfully completed his certified technician. Since 2002 he studied electrical engineering at the Chemnitz University of Technology. He received the diploma  degree in the main dicipline of power engineering in 2007. He then became a member of the scientific staff of the Siemens AG in October 2007. His fields of activity are traction converts.

Title of the paper

Investigation of Surge Current Capability of SiC MPS Diodes

Summary of the paper

In the paper the surge current capability of Silicon Carbide (SiC) Merged-Pin-Schottky (MPS) diodes is investigated. The diodes were impinged with trapezoidal respectively sinus shaped surge current pulses at different pulse times and temperatures. Thereby the diode structures provide a different  responsiveness depending on the diodes design. The destruction mechanisms for a sort of is temperature limitation of the material, in this case the anode metallisation. An other sort of diodes shows destruction at lower current density by occurring hot spots. While surge current, the first sort of diodes  reaches astonishingly high temperatures on the anode face. This sort of diodes was simulated with a simplified temperature model.

Award sponsors

Young Engineer Award in the press

2018 article Vienna University of Technology

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