Description: Over the past 5 years, the world of power electronics has changed with the emergence of wide bandgap power semiconductors. Power efficiencies have reached unrivaled levels higher than 99 % for non isolated converters. In isolated power converters, efficiency is now limited by losses in the conductors and transformer core.
Superconductors are materials that are able to carry currents exceeding several hundreds of amps at low temperature, e.g. the boiling temperature of liquid nitrogen (77 K = ‐196 °C).
The aim of this master thesis is to investigate the possibility of using a superconducting transformer in a switching power converter to overcome this limit.
The thesis will begin with a bibliographical review of papers on the application of superconductivity to power electronics, potential difficulties will be highlighted like the effect of switched currents on superconductors. Industrial usage of superconductors requires low temperatures with the associated cooling machinery. The extra cost induced by this cooling system will be industrially acceptable for quite high power applications (above hundred kW). Although the converter to be built during the thesis will be of the order of hundred watts, the topology will be chosen to allow future operation at higher power levels. Dual active bridges or LLC topologies are very good candidates.
A classical DC/DC converter will be built and tested at room temperature. Then, the transformer will be redesigned with the aim of immersing it at temperatures required to benefit from the superconductivity phenomenon.
Experiments will highlight the problems to be solved due to current densities and frequency effects. The impacts on magnetic components will also be analysed. The lessons learnt from these experiments will enable us to better assess the advantages and disadvantages of superconducting transformers regarding achievable power densities and efficiencies.
The thesis is coupled with an internship at CE+T Power, the company behind the project. The parts of the work not requiring extreme temperatures can be carried out within the company, while benefiting from expert engineers in power electronics. The other parts will be carried out in the “Measurement & Instrumentation” laboratory of the University of Liege.
The student choosing this subject will have the opportunity to work at the frontier of two exciting and rapidly evolving fields, at the heart of our society’s energy concerns.
Profile: electrical engineering or energy engineering, with a strong interest for experimental work.
CE+T Power offer:
Adresse Web: https://www.cet-power.com
Suggested course: ELEN0047 Superconductivity
Supervision: This master thesis is co-promoted by Professor Vanderbemden.
Contact : Fabrice Frebel - fabrice dot frebel at uliege dot be