| Work Detail |
The Fraunhofer Institute for Microstructure of Materials and Systems (Fraunhofer IMWS) has developed a methodology to improve inverter lifetime predictions, in order to help manufacturers reduce material usage and testing efforts while lowering production costs without compromising device lifetime.
Inverters for photovoltaic systems, battery storage and electromobility must withstand harsh environmental factors such as climate, dirt, high voltages and long operating times.
Despite these challenges, high-quality inverters typically last between 20 and 25 years. However, the specific construction methods, materials and designs that ensure this lifespan remain unclear, especially for newer applications such as photovoltaics and electromobility.
To address this problem, inverters are often designed with excessive safety margins, using materials and processes that offer durability without detailed knowledge of aging and failure mechanisms. The result is increased costs.
In response, Fraunhofer IMWS, the Institute for Machine Elements at the University of Stuttgart and the German companies SMA, Electronicon Kondensatoren and Merz Schaltgeräte have developed a methodology to improve lifetime and reliability predictions of inverters and their key components.
“Our results enable precise design in the development of new inverters and faster testing in quality control,” says Sandy Klengel, project manager at Fraunhofer IMWS. “This enables lower manufacturing costs, as we have a much deeper understanding of the behaviour of the components.”
Fraunhofer IMWS studied failure and aging processes in film capacitors and electromechanical switching devices such as DC circuit breakers and relay assemblies.
The researchers created defects and triggered degradation mechanisms under laboratory conditions using specially developed test setups. They took into account material interactions, varying electrical loads, and environmental influences such as seasonal temperature changes, humidity, and corrosive agents such as salt spray.
They then evaluated which phenomena were relevant to real-world use by comparing laboratory results to field-aged components that remained defect-free.
The results revealed problems such as cracks in the ceramic layers affecting insulation, formation of oxide layers, demetallization, polymer degradation, thermal damage and deterioration of welds. The researchers also observed crystalline deposits, local melting, contamination and failures in the housing components.
The team compiled these findings into a catalogue summarizing the types, characteristics and causes of the failures. They also used numerical simulations to better understand the physics of the failures, such as local current density and heat loss in the switches.
“With these results, manufacturers can reduce material requirements and testing effort, and therefore device costs, without compromising the reliability and lifetime of the inverters,” says Klengel. |
