Objectives and content
Power modules in IGBT (insulated gate bipolar transistor) technology are now at the threshold of their introduction to railway traction appilcations. Owing to the very rigorous operating conditions involved, above all the large temperature fluctuations between winter and summer and the frequency of the on and off states, very high demands are made on the reliability of these power devices: thus they must operate for 35 years without failures. However, the number of power devices used in railway traction applications will always be relatively small, so that the reliability requirements cannot be simply verified by experiment.
Hence the concept of buiit-In reliability must be consistently implemented. The core of the activities planned for the project therefore consists of the elaboration of accelerated reliability tests, whose scientific basis consists of the failure mechanisms and the corresponding models.
The requirements profiles of the tests are determined from the line profiles under normal and abnormal operating conditions. The end-users, i.e. the railway operators, will be involved in the work of defining the line profiles. All major applications, from tramways to high-speed trains, will be examined in this process. In addition to testing the IGBT power modules separately, it appears to be particularly important to test them within the system as well. To this end, assemblies for worst-case operation (AWCOs) are to be developed and operated for test purposes.
Planned flanking measures include work on alternative contacting techniques as well as an investigation into whether any reliability indicators exist that allow module degradation to be indicated in a simple way. The reliability simulation of the system should permit a reliability prediction to be made on the basis of models for failure modes. All these activities should result in the concluding of an agreement on standardized reliability tests by the end-users (railway operators), the power semiconductor manufacturers and the transportation industry. This agreement should then be proposed as an IE standard.
Funding SchemeCSC - Cost-sharing contracts
LN1 1SG Lincoln
CB2 1PZ Cambridge