Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Reliable and extremely long-lasting – high-voltage power electronics for network expansion

04.08.2015

How is it possible to increase the dielectric strength and reliability of power modules for medium- and high-voltage applications?

This question was addressed by scientists at Rogers Germany GmbH, an insulating substrate manufacturer based in Eschenbach, Germany, and the Fraunhofer Institute for Integrated Systems and Device Technology IISB in Erlangen.


Large DBC card with 24 different test designs for partial discharge tests.

Fraunhofer IISB

In the framework of the APEx research project, the researchers developed new construction and testing techniques for high-voltage modules. The project was supported by the German Federal Ministry for Education and Research (BMBF) for over two and a half years with approx. 1.3 million euros and was coordinated by the Fraunhofer IISB.

Today, power electronics systems are already found along the entire power generation chain – from the power station to the consumer. These systems continue to grow in importance due to the German federal government's decision to expand the energy networks.

Power electronic systems are the key components for an efficient transmission and distribution of electrical power and for ensuring network stability. Power modules with voltage classes up to 6.5 kV have become established in industrial drive technology and in rail technology. However, the new applications in energy technology make considerably higher demands of the dielectric strength and the reliability of these modules.

The main ceramic insulator, the socalled DBC insulating substrate (DBC: "Direct Bonded Copper") can be regarded as the central component of the power modules. The DBC substrate serves as a circuit carrier and accommodates the electronic power devices. The electrical contacting of the devices and the actual wiring of the circuit take place via a copper layer on the substrate surface that is formed by etching.

In the project "Construction and Testing Technology for Extremely Durable High-Voltage Modules" (APEx), it was possible to increase the dielectric strength of currently available DBC insulation ceramics using an optimized module design. In addition to specific material characteristics, the electrical field distribution in and around the insulator is a significant influencing factor, among others.

Increases in the electrical field strength especially occur at the edge structures of the etched copper layer. The field increases cause local insulation currents, socalled partial discharges, in the surrounding insulating material, which can considerably reduce the lifetime of the power modules. The amount of the field increases depends on the applied voltage on the one hand as well as strongly on the geometric form of the edge structure on the other. For this reason, it can be influenced in a relatively cost-neutral way.

To optimize the edge structures, the maximum field strengths that occur on different designs had to be simulated and associated with partial discharge measurements. A comprehensive, simulation-based preliminary investigation of the field strength distribution on the edge structures of the DBCs identified the principal geometric and material-specific influencing factors and allowed a basic theoretical understanding of the interactions.

This also required a review of the simulation tools as well as the models used, especially to circumvent so-called unavoidable singularities. In numerical simulation, the modeling of ideal edges can produce excessive values for the field strengths that occur. With the FEM simulation (FEM: "Finite Element Method") used for this, it is therefore essential to have the right lattice parameters and select suitable measuring points to be able to exclude gross distortions of the calculated field strength distributions.

The findings obtained from the simulations and the newly developed ideas were confirmed by partial discharge measurements on corresponding test designs with adapted edge structures. Thanks to the support of the BMBF, it is now also possible – in addition to purely indirect measurement – to detect the precise point or origin of partial discharges visually using a UV camera system at Fraunhofer IISB.

To increase the reliability and lifetime of power modules, tests were also carried out on coating systems in the framework of APEx. Filling microcracks and insulating gaps with suitable inorganic and organic materials considerably increased the mechanical resistance. Accelerated aging tests on module-oriented set-ups in temperature shock cabinets demonstrated the improved thermal fatigue resistance or storage stability of the DBC modules coated in this way.

APEx was supported in the framework of the BMBF support program "IKT 2020 – Research for Innovations". One objective of IKT 2020 is to develop innovative materials and components in electronics for the application field of energy supply.

On the basis of the modifications for DBC power modules studied in APEx, initial prototypes were produced at Rogers Germany GmbH. The optimization of the edge structures as well as the coating technology can be used individually or in combination to improve the product characteristics. The methods can be used on existing DBC layouts as well as on standardized power module dimensions.

The continued decentralization of the energy supply in the medium- and high-voltage sector suggests an increasing demand for breaker cells with an extremely long lifetime of 40 or more years in continuous operation as well as with high dielectric strength. Last but not least, this makes the availability of such components strategically important for the energy industry.

Images for editorial use can be found at http://www.iisb.fraunhofer.de/presse.

Contact

Andreas Schletz
Fraunhofer Institute for Integrated Systems and Device Technology IISB
Schottkystrasse 10, 91058 Erlangen, Germany
Phone +49 911 23568 - 27
Fax +49 911 23568 - 12
andreas.schletz@iisb.fraunhofer.de

Fraunhofer IISB

Founded in 1985, the Fraunhofer Institute for Integrated Systems and Device Technology IISB conducts applied research and development in the fields of power electronics, mechatronics, microelectronics and nanoelectronics. The work of the institute in power electronic systems for energy efficiency, hybrid and electrical automobiles as well as in technology, device and material development for nanoelectronics enjoys international attention and recognition.
In the business area of power electronics, the primary focus is on topics such as innovative circuit and system solutions for highly efficient and compact power converters, mechatronic 3D integration, multifunctional integration and use of new materials and semiconductor devices. Application fields include e.g. electrical energy transmission, drive technology, switching power supplies and voltage transducers, components for vehicle technology and vehicle models, construction and connection technology for passive and active power modules as well as lifetime and reliability tests. Fraunhofer IISB additionally has extensive experience in the area of error analysis. This applies to all levels of electronic circuits, from chips to chip contacting, housings and circuit carriers or insulation substrates, up to passive devices.
Around 230 employees work in contract research for industry and public institutions. In addition to its headquarters in Erlangen, the IISB also has two further locations in Nuremberg and Freiberg. The IISB closely cooperates with the Chair of Electron Devices at the Friedrich-Alexander-University Erlangen-Nuremberg.

Weitere Informationen:

http://www.iisb.fraunhofer.de/presse Press release and Images for editorial use.

Presse Institute | Fraunhofer-Gesellschaft

Further reports about: BMBF COPPER Device IISB circuit drive technology energy supply material measurements voltage

More articles from Power and Electrical Engineering:

nachricht Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH

nachricht To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>