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Design with IGBT modules for high power inverters

Posted: 18 Aug 2008 ?? ?Print Version ?Bookmark and Share

Keywords:IGBT module? power inverter design? IGBT? converter?

By Piotr Luniewski and Uwe Jansen
Infineon Technologies AG

Although IGBT modules with blocking voltages up to 6500 V are available, many applications require the design of inverters with ratings close to or even beyond 1MVA with 1,2000V or 1,7000V devices. Applications like variable speed drives, UPS systems, heavy-duty commercial vehicles and grid connection of microturbines or renewable energy systems like windmills or large solar farms often imply restrictions that don't allow to design with higher voltage levels. The recently introduced PrimePACK module housing, together with the new IGBT4 technology in 1,200V and 1,700V, fits to this market by enabling a cost effective and modular inverter design.

Heatsink size
Every converter design, regardless of its final application, faces at least two problems: power part volume and efficiency. When a converter dedicated to high power application is considered in power electronic equipment consisting of IGBT modules, DC-link capacitors and heatsink are usually installed in control cubicles having a height of 1.80- to 2.20m, airflow from bottom to top and placed in front of a wall. An alternate approach uses racks where several heatsinks placed above each other are cooled by a horizontal airflow entering the cabinet at the front and leaving it at the backside. In both cases the most important dimension for the end user is the width of the cabinets.

To limit overall equipment size, it is therefore advantageous to use a heatsink as long and deep as possible but with limited width. Hence, a PrimePACK module with narrow and long baseplate helps to achieve the right heatsink dimensions and proper heat distribution. Further reduction in heatsink volume is possible by operating this module with extended junction temperature Tvjop = +150C. Figure 1 shows that increasing operating junction temperature is a much more useful means to increase power dissipation than to increase heatsink size significantly beyond module footprint.

Converter efficiency is mainly determined by the semiconductor technology used for IGBTs and diodes. Hence, in the recent years much effort has been spent to tailor semiconductor technology to the different applications and power levels. To meet the growing requirements for energy efficiency, the PrimePACK module is equipped with the Trench-/Fieldstop IGBT4 generation. The module family is dedicated for two inverter power levels: medium (E4) and high power (P4) in 1200V [1] and 1,700V class.

Figure 1: Power dissipation of a 150mm x 150mm module at different junction operating temperatures

Cutting voltage drop, switching losses
Major focus has been set on further reduction of forward voltage drop and switching losses. However, especially in high power applications, the small dynamic losses are not the main target. To cope with overvoltages and EMI, appropriate controllability and certain softness during module switching is required and seen as main development target [2]. With various current ratings, PrimePACK modules provide a good match to converters with different power range without changing the module housing.

Figure 2: Flexible driver system consisting of MA300Exx, 2ED300E12-SFO and 2ED300C17-S for 1200 V and 1700V PrimePACK modules

As most of converters consists of several branches where each one has two IGBTs in series the PrimePACK module is in half-bridge configuration together with FWD diodes embedded in one housing. This type of internal layout and connections reduces stray inductances in commutation loop compared to leg composed from single modules.

Increased power of the inverter system can be realized by parallel connection of smaller inverters or by paralleling modules in one inverter design. The long and narrow module shape and the half-bridge configuration are especially beneficial, while paralleling modules in one inverter is preferable.

Modularity of power inverter system on one side is given by system oriented module design but on the other side the IGBT driver must support the flexibility goals. Efficient use of modules in parallel connection with optimized current balance requires applying a suitable IGBT driver approach [3]. Figure 2 shows an example of it where driver system can be used for 1,200V as well as for 1,700V PrimePACK modules with minor changes. This driver kit is suitable for driving up to three modules in parallel. In any case one EiceDRIVER 2ED300C17-S drive and one 2ED300E17-SFO adapter board is necessary. Number of module adapter boards MA300EXX is always the same as number of modules [4], [5].

Figure 3: 2ED250E12-F evaluation driver board for 1200V single PrimePACK module

In a converter requiring only one high power module and modularity in parallel operation is not needed, the driving system can be optimized resulting in cost and volume reduction. The PCB driver called 2ED250E12-F employing an EiceDRIVER-IC 1ED020I12-F [6] and dedicated to the 1,200V devices of the PrimePACK family is depicted in Figure 3. With the Coreless Transformer technology [7] and protection functions implemented in the design, the 2ED250E12-F driver complements the PrimePACK module to a building block comparable to an IPM (Intelligent Power Module) in half-bridge configuration.

PrimePACK modules today are available in 1,200V and 1,700V class, various current ratings and two different IGBT technologies. This approach makes these modules mechanically universal and electrically suitable for many high power applications. Finding a perfect match to final design by appropriate trade off between static and dynamic loses is additionally supported by a modular driver approach [3].

[1] M. Baessler, et. al.: 1200V IGBT4 Low and Medium PowerChips designed to the Needs of the Application, PCIM Europe, 2007
[2] M. Baessler, et. al.: 1200V IGBT4High Powera new Technology Generation with Optimized Characteristics for High Current Modules, PCIM Europe, 2006
[3] P. Luniewski, et. al.: Benefits of System-oriented IGBT Module Design for High Power Inverters, EPE 07
[4] AN-2007-06, MA300E12 / MA300E17 Module Adapter Board for PrimePACK IGBT Modules,
[5] AN-2007-05, 2ED300E17-SFO Evaluation Board for 2ED300C17-S /-ST IGBT Driver,
[6] Infineon Technologies AG: Target datasheet Version 1, EiceDRIVER, 1ED020I12-F, Single IGBT Driver IC,
[7] A. Volke, at. al.: IGBT/MOSFET Applications based on Coreless Transformer Driver IC 2ED020I12-F, PCIM Nuremberg, 2004.

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