ECPE ESREF Workshop Humidity and Condensation in Power Electronics Systems

The workshop was held on 25th of September, Toulouse, France in the framework of 30th European Symposium on reliability of Electron Devices, Failure Physics and Analysis. Well visited workshop comprehended invited presentations followed by the discussion with the audience.

1. Introduction, Andreja Rojko - Mitsubishi Electric R&D Centre Europe and Michel Piton - Alstom, France

Two ECPE activities related to Humidity issues in power electronics were outlined:  (1) ECPE Workgroup ‘Power Semiconductor Reliability for Railway Application’ which is preparing ECPE Guideline on ‘Technical Specifications for Railway Applications: HV-H3TRB tests’ and (2) recently organized ECPE Workshop ‘Humidity and Condensation in Power Electronic Systems’.

2.Humidity and Condensation in Power Electronics Systems: Challenges for Railway Traction, Michel Piton - Alstom, France

The presentation addressed three challenges in the railway traction applications: (1) development of the models for microclimate around power semiconductor devices based on the environmental conditions, (2) estimation of converter lifetime under humidity influence, and (3) qualification and testing strategy. It was discussed how to transfer power cycling methodology to the humidity testing and define qualification strategy. Finally it was stressed that those tasks request close cooperation between semiconductor suppliers, converter manufacturers and railway operators.

3. Model-Based Condition Monitoring of Power Semiconductor Devices in Wind Turbines, Michael Hanf - University of Bremen, Germany

The focus of presentation was wind power application. Field data showing ingress of humidity in the converter cabinet were shown and discussed. Analyzed data showed that stress due to humidity is moderate and there are no indication of condensation in the converter cabinets. Currently valid models predicts life time for wind turbines based on real mission profiles over 100 years. However big data (also measurement campaign) show correlation between high humidity and converter failures. It was suggested that beside devices also other components as gate drivers, Dc link capacitors and busbar should be tested. On general the converter should be tested as whole.

4. Some Experiences with HICon: Humidity robustness experiment, Stefan Mollov - Mitsubishi Electric R&D Centre Europe, France

Presented were humidity robustness test results of HiCon (highly integrated converter). The results were compared to the results of testing TO247 SiC MOSFET devices. Although some failures in HiCon cannot be identified yet HICon appears to be better (at least no worse) than TO247.

5. Humidity-related Degradation Mechanisms of Capacitors, Huai Wang - Aalborg University/CORPE, Denmark

In the presentation the humidity related degradation of film capacitors was addressed. Some test results were presented and discussed, Although it is widely assumed that film capacitors are more reliable than Aluminum electrolytic capacitors this has proven not to be the case.

General discussion

In general discussion it was again stressed that other components beside semi-conductor devices may compose biggest percentage of humidity related failures. Further it was discussed if controlled climate in the converter box would not be the best solution for the humidity issues in power electronics. Namely due to the complexity of the problem it is unlikely that enough precise models, and lifetime prediction methods can be developed.



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