Power electronics is one of the most important key enabling technologies in changing society from a fossil fuel based society to a much more sustainable one. More than 70 % of all electricity is processed through power electronics which justifies the establishment of a Center Of Reliable Power Electronics (CORPE) at Aalborg University aiming to design more reliable and more efficient power electronic systems for use in power generation, distribution and consumption.

The center will address better understanding of how reliability of power electronic devices and systems is influenced by different stress factors such as temperature, overvoltage and current, overload and environment.

The center is established in close collaboration with major Danish power electronic companies, Aarhus University, two leading European universities and one U.S. university.

Further, the center will develop device and system models that will enable simulation and design of power electronic systems very close to the limits of the devices and enable designed reliability. The knowledge will also be used online during operation to predict lifetime and enable smart derating of the equipment still in operation and ensure longer lifetime. The objectives will be:

• Power electronic systems will be more reliable
• More efficient
• More competitive (price) by reducing maintenance and operation costs.
   

Research will be carried out on three different levels in order to cover the entire scope of reliability and to be able to develop tools to design for reliability. Based on analysis of failure analysis from the system level, research will be conducted on the component, converter and system level.

The figure below illustrates the center activity with the locations of the main contributions from the partners.

The research needs to be multidisciplinary and integrated between the partners but most input and efforts from industry will be at the system level (both in terms of feedback from the market and new designs) whereas research at the universities will mostly be dominant at the component and converter levels where models and tools are developed.

The research is divided into six tasks covering the entire range of activities from basic reliability modeling, testing up to predicted reliability system level design.

Task 1

Analysis, understanding and modeling of failure mechanisms & field load. The very large number of power electronics components installed in various power electronic systems by companies participating in the project form an unique basis for analysis of failure mechanisms in components exposed to field operation conditions.

Task 2

Lifetime prediction and design. Lifetime calculations can be based on empirical equations where the input, e.g. is the temperature profile of the module. It can also be based on physics of failure modeling including stress analysis. Some failure mechanisms are well known and modeled based on accelerated testing. But new components require characterization and the analysis in task 1 is expected to direct attention to new areas.

Task 3

Accelerated test and verification. Based on the reliability analysis in WP1 and models in task 2, components are selected for further tests where the external stress factors (current, voltage, temperature, humidity, etc.) are controlled in order to accelerate degradation of specific elements in the components like busbar, wirebond, chip solder and substrate solder. This will produce valuable input to lifetime modeling in task 2.

Task 4

Design tools for power electronic converter and system. A design platform including different state-of-the-art models of power electronic components will be developed. The platform will include electrical, thermal and mechanical dependent lifetime models.

Task 5

Real time monitoring and prediction in components and systems. Identifying methods for the real time (on-line) detection of the lifetime (wear-out) state of the power transistor (or power diode) by monitoring various relevant (thermal, electrical, optical etc.) sensor signals. This work will build on the results from task 1 and task 2, and an important task here is to make possible the desired real time detection during normal operation of a power converter.

Task 6

Application design:

The developed methods and models are validated through four different designs based on their mission profiles and they are expected to be tested in the field.