power4re: Research project launched to increase the reliability of converters

The research project »power4re« (reliable converters for regenerative energy supply) started with a virtual kick-off in mid-April. Under the direction of the Fraunhofer Institute for Wind Energy Systems IWES, five institutes of the Fraunhofer-Gesellschaft are working together with industry representatives on solutions aimed at increasing the reliability and robustness of inverters in photovoltaic systems and frequency converters in wind turbines. power4re is being funded under the internal research program PREPARE of the Fraunhofer-Gesellschaft with funds totaling 3.5 million euros. Converters are of central importance in the energy transition: They are indispensable technical components for the grid connection of photovoltaic and modern wind energy plants so that the regeneratively generated energy can be fed with grid-compliant voltage and frequency. The converters must, therefore, be highly reliable. However, they are exposed to particularly challenging operating and environmental conditions. For years, they have been some of the most frequently failing system components, often resulting in considerable costs. This means there is an urgent need for durable converters that are resistant to environmental influences. They therefore have a high economic potential as an indispensable technological component of the energy turnaround.

© Fraunhofer IWES
IGBT module of a wind turbine converter

The aim of the three-year project is to develop solutions that can significantly increase the reliability and robustness of converters for decentralized electrical energy conversion. The team will focus on application-specific weak points that have been identified from comprehensive field data and damage analyses and whose failure mechanisms – often resulting from a combination of climatic stress and electrical load – are to be investigated in greater detail within the project. In addition to hardware modifications and protection concepts, the project will also address suitable test procedures in order to be able to evaluate them under typical application conditions.

Another important aspect is the expansion of longer-term alliances between Fraunhofer Institutes. A total of five Fraunhofer Institutes are involved in the power4re project: the Fraunhofer Institute for Integrated Systems and Device Technology IISB, the Fraunhofer Institute for Microstructure of Materials and Systems IMWS, the Fraunhofer Institute for Solar Energy Systems ISE, the Fraunhofer Institute for Wind Energy Systems IWES (project management) and the Fraunhofer Institute for Reliability and Microintegration IZM. In addition, the power4re project is being accompanied by a circle of consultants that includes the companies ConverterTec (formerly Woodward Kempen), SMA Solar Technology AG, and Mitsubishi Electric R&D Centre Europe. On behalf of the Fraunhofer-Gesellschaft, the project is supervised by Dr. Vera Gramich from the Internal Research Programs department.

»With power4re, we are continuing to advance a socially acceptable energy transition in cooperation with our project partners, because increasing the reliability of wind energy and PV systems is vital in further reducing the production costs of regeneratively generated electricity. We can competently bring our comprehensive and long-standing system understanding of converters to bear in this area,« says Prof. Jan Wenske, Deputy Head of the Institute and Technical Director at the Fraunhofer IWES.

»We are developing new methods for field-data-based failure cause analysis and are working on condition monitoring that concentrates on the relevant failure mechanisms. We hope that the cross-institute cooperation will provide us with new and important insights, for example from comparison with PV applications,« adds Dr. Katharina Fischer, Project Manager and Senior Scientist at the Fraunhofer IWES.

The Fraunhofer IMWS is thus contributing its expertise in the material diagnostics of devices, components, and materials used in electronics, in particular regarding corrosion processes affecting electronic components such as wire bond contacts, metallic housing materials, metallization systems for substrates, and electronic contacts. The project is also focused on material evaluation and analysis of degradation mechanisms of insulation materials under the influence of humidity and electric fields, as they are often used in applications such as wind turbines.

Investigations into microstructure, material interactions, or defect formation will be correlated in detail with technology, material selection and design, and conditions of use. The research team in Halle will use methods of material characterization, microstructural diagnostics, complex physical failure analysis, and life cycle prediction in addition to numerical simulation. Apart from findings pertaining to the effects of the manufacturing process and the operating conditions on inverters, the necessary diagnostic, inspection, testing and modeling procedures are also being further developed.

The solutions aimed at increasing converter reliability are not limited to wind energy and photovoltaic applications, but can potentially be transferred to other sectors such as railways, avionics, and electromobility, where converters are also exposed to challenging environmental conditions.