SuperGrid Institute is going global! Next week, Arthur Boutry will be crossing the Atlantic to collaborate with the Center for Power Electronics Systems (CPES), a laboratory at Virginia Tech (listed by The Times as one of the top 300 universities in the world in 2019!). During his time in the USA, Arthur will continue his work on designing MMC sub-modules for HVDC applications as part of his PhD which he began in 2018 at SuperGrid Institute, in collaboration with the Laboratoire Ampère. Arthur received a grant from the American government for his exchange year in the form of a Fulbright scholarship, one of the most prestigious and competitive fellowship programs in the world. An impressive accomplishment!
This Tuesday the 10th of July, Michel MERMET-GUYENNET presented a keynote speech at the 13th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2019) in Toulouse, following the invitation of Bernado COGO from the Antoine de Saint Exupéry Institute of Technology (IRT Saint Exupéry). In his paper, Michel MERMET-GUYENNET presented power electronics technologies for MV and HV grids.
This paper proposes an in-depth analysis from the control point of view of dynamic models of a Modular Multilevel Converter (MMC) for high-voltage direct current (HVDC) application. Firstly, a generic method of analysis is presented for a natural arm-level state-space model. Its structural analysis highlights the decoupled nature of the MMC. Secondly, the well-known sum and difference of the upper and lower arm state and control variables is considered to obtain a (S/D) model. This transformation leads to a coupling between state and control variables and to an increase of the system complexity. Using the analysis results of the natural model and the (S/D) model, an original arm-modular control is finally proposed. The simulation results show the effectiveness of the proposed control, which is simpler to design compared to a conventional (S/D) control.
This year, for the first time our presence at PCIM Europe 2019, was noticeable with our stand from 6th to 9th May. At the conference, and as power electronics is at the heart of our innovations, SuperGrid Institute was invited to present during the « Smart Transformers » special session.
Power electronic traction transformers in 25 kV / 50 Hz systems: Optimisation of DC/DC Isolated Converters with 3.3 kV SiC MOSFETs
In AC electric trains, power electronic traction transformers (PETT) are multilevel single phase AC/DC converters connected to the AC medium voltage overhead line. For indirect topologies, DC/DC isolated converters are key elements of PETTs. This paper shows a method to design such DC/DC converters, and several variants are considered. Finally, the comparison results, in the case of a 25 kV / 50 Hz power supply and 3.3 kV SiC MOSFETs, show that the variant with a resonant AC link, with only one controlled bridge and a switching frequency lower than the resonant frequency, offers the best efficiency at rated power for a given volume.
The main objective of this thesis is to develop a methodology to size PETT topologies, in order to compare them.
PhD Quentin MOLIN « High Voltage SiC MOSFET Robustness study: threshold voltage shift and short-circuit behaviour »
This manuscript is a contribution to reliability and robustness study of MOSFET components on silicon carbide “SiC”, wide band gap semiconductor with better characteristics compared to silicon “Si” material. Those new power switches can provide better switching frequencies or voltage withstanding for example in power converter. SiC MOSFET are the results of approximately 10 years of research and development and can provide increased performances and weight to some converter topology for high voltage direct current networks.
Gate-oxide technology weakness is a main reliability issue of Silicon Carbide MOSFET transistors. The threshold voltage shift is a critical phenomenon that addresses the reliability of industrial power applications. It is important to have a better understanding of the phenomena implied in the gate threshold voltage shift. In this context, HTGB test is proposed and the resulting gate oxide stress is studied and discussed in this paper.
Robustness study for the 1.7 kV SiC MOSFET is presented. After evaluation of the critical energy required for failure, devices were submitted to repetitive short-circuits conditions.
This article presents the design, the fabrication, and the test of an isolated DC-DC converter for renewable energy applications. The converter is based on the Dual Active Bridge topology and uses silicon carbide power semiconductors and a medium frequency transformer. The design process covers hardware ranging from the semiconductor die to the complete power converter. For the control, a rapid prototyping approach was used. The experimental validation of the 100 kW prototype is presented.