Best Paper and Three Young Engineer Awards Presented during PCIM Opening Ceremony

May 13, 2013 by Power Pulse1595211359

Four outstanding conference papers were selected from more than 280 papers by the Conference Directors. The determining criteria were originality, topicality and quality. The Young Engineer Awards were presented to exceptional contributions from young professionals (under 35 years old). The awards were presented by the Scientific Advisory Board Chairman, Prof. Leo Lorenz of ECPE, Germany.

The papers were delivered for the first time at the PCIM Europe 2013 Conference and are published in the proceedings. The three Young Engineer Award winners received prize money, while the Best Paper Award winner received prize money and an invitation to the PCIM Asia 2014 Conference in Shanghai. The winner of the Best Paper Award is: Eckart Hoene of Fraunhofer IZM, Germany for "Ultra-Low-Inductance Power Module for Fast Switching Semiconductors."

The three PCIM Young Engineer Awards have been given to: Radoslava Mitova of Schneider Electric, France for “Half Bridge Inverter with 600V GaN Power Switches.” Samuel Araujo, University of Kassel, Germany for “High Switching Speeds and Loss Reduction: Prospects with Si, SiC and GaN and Limitations at Device, Packing and Application Level.” And Daniel Wigger, University of Rostock, Germany for “Impact of Inhomogeneous Current Distribution on the Turn-off Behavior of BIGTs.”

The following are the original abstracts and complete author listings for each of the winning papers:

Ultra-Low-Inductance Power Module for Fast Switching Semiconductors; Eckart Hoene, Andreas Ostmann, Binh The Lai, Christoph Marczok, Fraunhofer IZM, Germany; Andreas Müsing, Johann Walter Kolar, ETH Zürich, Switzerland

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 band-gap 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. (Picture Prototype 1200V SiC.jpg)

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.

Half Bridge Inverter with 600V GaN Power Switches; Radoslava Mitova, Alain Dentella, Miao-Xin Wang, Schneider Electric, France; Rajesh Ghosh, Uday Mhaskar, Schneider Electric, India; Damir Klikic, Schneider Electric, USA

The emerging Gallium nitride (GaN) power devices promise to outperform the legacy silicon devices and challenge the Silicon carbide devices in 600 voltage range; thanks to their faster switching speed and low switching and conduction losses. In last few years several device manufacturers have communicated their development on GaN based power devices in the range of 200-600V. This article presents the evaluation of a new 600V GaN High Electron Mobility Transistor in a half-bridge inverter prototype. The static and dynamic characterizations of these devices are presented. Several experiments have been conducted to test the GaN HEMT performances. The results shows that the GaN based devices improves the efficiency of the inverter prototype compared to the silicon and SiC based devices. The advantage of using higher switching frequency, as can be obtained using the GaN switch, on the size of the inverter output filter inductor is also commented.

High Switching Speeds and Loss Reduction: Prospects with Si, SiC and GaN and Limitations at Device, Packing and Application Level; Samuel Araujo, Thiemo Kleeb, Peter Zacharias, University of Kassel, Germany

The prospect of increasing the switching frequency without sacrificing efficiency is seen in many fields of application as a promising development for the current decade. 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. In the path towards such development it is thus interesting to identify the true limitations for each device technology based on inherent properties and also on properties of the freewheeling path. Several enhancements in the field of packing and montage are also still necessary in order to fully exploit the referred power devices’ capabilities. In addition to this, other issues at application level concerning EMI, driving and also the influence of transient speed at inductor losses still need to be addressed. This paper will present an overview of these issues based on experimental results and literature research in order to assert future development trends. In addition to this, a benchmarking of different SiC switch technologies based on a new figure of merit will be performed here.

Impact of Inhomogeneous Current Distribution on the Turn-off Behavior of BIGTs; Daniel Wigger, David Weiß, Hans-Günter Eckel, University of Rostock, Deutschland

BIGTs are a new type of power semiconductors. In opposite to a conventional IGBT/diode-module, this device includes the functionality of the diode and the IGBT. An advantage of the device is the softness of the turn-off behavior in the IGBT-mode compared to a conventional IGBT. The reason for this is the inhomogeneous current distribution in the BIGT.

The BIGT has a different chip design, compared to an IGBT. The BIGT chip contains the pilot-IGBT with a conventional design and the RC-IGBT with the shorts on the collector. The pilot-IGBT is needed to prevent the snapback effect. Due to the lack of the shorts the p-emitter efficiency is higher in the pilot area. As a reason of that, the plasma concentration during the on-state is higher in the pilot-IGBT, as in the RC-IGBT. The inhomogeneous charge carrier distribution will have an influence on the turn off behaviour in the IGBT mode. This turn off behaviour has been investigated at different current level and compared to a state of the art IGBT. At low current the BIGT has a significant higher dvCE/dt and a lower overvoltage. The large hole density in the pilot area causes a high dE/dx and a short space charge region at the same blocking voltage. So there remains a lot of charge in the BIGT, which leads to a large tail current. At high current the high dE/dx in the pilot-IGBT will cause the dynamic avalanche. Due to the dynamic avalanche the dvCE/dt and the di/dt will be limited. Compared to the IGBT the inception voltage of this effect in the BIGT is significantly smaller, that’s why the device is softer than the conventional IGBT.

A higher temperature leads to a higher charge carrier density in the IGBT and the BIGT. Besides the temperature influence the charge carrier distribution in the BIGT. Due to the lower forward bias voltage of the pn-junction on the collector and the lower mobility`s µp,µn the difference of the charge carrier density between the pilot-IGBT and the RC-IGBT is smaller. At small current the dvCE/dt significantly decrease with the temperature. In opposite to the IGBT, where the inception point of the dynamic avalanche only slightly increase, the inception point of this effect in the BIGT shows a strong temperature dependency. In the IGBT the higher avalanche field strength will be compensated by a higher hole density. Due to the fact of the less inhomogeneous current distribution in the BIGT, there is no increase of the charge carrier density and so the dynamic avalanche starts at a significantly higher voltage. At high temperature only a small difference in turn off behaviour between the BIGT and the IGBT can be seen.