IRT Saint Exupéry pursues a series of portraits devoted to the men and women who best represent the institute: its researchers. Their high-level skills and wealth of experience contribute hugely to IRT Saint Exupéry’s performance and unique position, which is so crucial for its members and partners.
Bernardo Cogo, 41, is a Senior Expert in power electronics. A passionate researcher and a real Swiss Army knife, Bernardo tells us about his journey from Brazil to France.
Can you tell us about your background?
Originally from Brazil, I studied electronics in a technical high school located on the campus of the Federal University of Minas Gerais in the city of Belo Horizonte. I continued my studies in the same university with a 5-year degree in electrical engineering, including a year of exchange with the University of Texas in the United States. I then specialized in power electronics.
Once back in Brazil, I completed a master’s degree, which unlike in France takes 7 years, during which I carried out several research activities that lead to more substantial publications. In 2004, I was lucky enough to obtain a grant from the European Union to do the “practical” part of this master’s degree, which took place in France, and more precisely in Toulouse at the Laplace laboratory (which was called at the time L2EI – Laboratory of electrical engineering & industrial electronics). It was my first time in France. After that, I worked for one and a half year in Brazil, where I was teaching in 3 different universities.
At the beginning of 2007, I got again a grant, Brazilian this time, to do my thesis and I went to France to start my research. It is here, in Toulouse, at the LAPLACE laboratory that I did my thesis for almost 4 years with occasional university exchanges such as with the University of Laval, in Quebec. At the end of October 2010, I defended my thesis and obtained my PhD. After this thesis I started to work, still on the research part. I did a 13-month post-doctorate in Switzerland, at the ETH (Swiss Federal Institute of Technology Zurich), then a second one in France, financed by the CNRS where I was attached to the LAAS laboratory but physically worked on the 3DPHI (3D Power Hybrid Integration) platform at the LAPLACE laboratory.
How did you make the transition to IRT Saint Exupéry?
In 2014, while I was doing a contract at Toulouse Tech Transfer for the valorization of a patent, I started to hear about the IRT Saint Exupéry. It was my meeting with Régine Sutra-Orus, then Director of the More Electrical Aircrafts Domain, that accelerated everything: I was hired by Zodiac in order to be seconded at the IRT Saint Exupéry on high ambition projects.
On the 1st of December 2014, I started my adventure at IRT as a power electronics expert within the INTEGRATION project whose main objective was the optimization of a power drive system by increasing the power density of the electrical system and reducing the weight of all components.
A few years later, IRT Saint Exupéry hired me as a Senior Expert in power electronics, aiming to perpetuate this key competence.
Indeed, power electronics plays a very important role in the missions of the “Greener Technologies” axis. Power electronics mainly deals with power and energy conversion thanks to devices that enable the nature and shape of electrical energy to be changed.
Electrical energy is present in a certain form (voltage and current) and must be used in another form. Our work consists in making this energy usable for some specific applications. The most typical case in our work concerns electrical loads present in an aircraft, where the energy comes from the electrical generators attached to the turbines, and must be used by actuators, heaters, or air conditioning systems for example. Most of these systems use motors and require electrical energy specific to their needs, generated by energy converters.
Can you tell us more about your role at IRT Saint Exupéry?
I am a Senior Expert in power electronics and work on 8 different projects. The most important one in terms of size and budget is the EPOWERDRIVE project whose objective is to propose to members technological and methodological solutions to reduce volume, increase power density and reliability of electromechanical chains.
I am also involved in the CHPA project, in 4 European projects (3 CleanSky and one SHIFT2RAIL), in the SICRET project for which I provide expertise to Fabio Coccetti‘s center of competence and in 1 project that has just been launched – OCEANE which is a continuation of the EPOWERDRIVE project.
I have a very transverse work in the projects of the Greener Technologies axis. I am mainly a researcher, but I am also involved at many other levels: supervision, internal and external training, promotion of the IRT through presentations in workshops, etc. I am also very involved in Business Development and act as an interface on the subject of power electronics: I discuss with industrial partners to set up new projects and maintain strong relations with our academic partners.
What are the main results of the EPOWERDRIVE project?
The EPOWERDRIVE project has produced many results, some of which have been patented and many of which have been transferred to our members for industrial applications.
I am thinking in particular of the SiC (silicon carbide) inverter, which is a generic three-phase inverter used to understand SiC converters.
This demonstrator, first developed within the framework of the INTEGRATION project, then used within the EPOWERDRIVE project, demonstrates the capacity of realizing a converter with a commercial SiC module.
EPOWERDRIVE Project
Budget : 7 174 811€
Members : AEROCONSEIL SA ; AIRBUS SAS ; APSI 3D ; ELVIA PCB ; LIEBHERR AEROSPACE TOULOUSE SAS ; MOTEURS LEROY SOMER; TFE Electronics; SAFRAN
Informations : This project focuses on the study of EMC, multi-stress optimization methods, the different components of the chain in order to optimize the power density, efficiency, reliability and manufacturing cost.
Silicon carbide is a very good energy conductor but the industrials were a bit reluctant to use it at the time because of its novelty. Our role was to show them the advantages of its use and its very high performance.
This demonstrator was transferred to one of our industrial members who estimated a gain of 6 months of internal research on this theme thanks to this acquisition.Today it remains a promising demonstrator which is still used within the OCEANE project, and even during demonstrations in some international conferences or training courses that I give, notably at ICAM.
What do you appreciate the most in your work at the IRT?
I like to use my scientific contribution to solve the problems of our industrial and academic members in the framework of major projects. But it is also the freedom and diversity of actions that I like: I do internal and external trainings, I give courses, I use my expertise for other IRT competence centers, through analytical and numerical computations, simulations and experiments, all this within a great team.
The IRT has evolved a lot in the last 8 years. Today, our members recognize the value of our work and our skills and come to us for our expertise. This is very appreciable.
Do you have a reflection to share?
Despite all my other activities, I consider myself mainly as a researcher: that’s what I am and that’s what I’m passionate about. I do research and I will always do it!
PUBLICATIONS LIST
B. Cougo, R. Riva, H. Hoffmann Sathler. Caractéristiques de commutation d’un module SiC faible inductance avec condensateurs intégrés pour les applications aéronautiques
Symposium de Génie Electrique, Université de Lorraine [UL], Jul 2018, Nancy, France
B. Cougo, L. Morais, R. Riva. Influence de méthodes PWM sur le cyclage thermique des semiconducteurs d’un onduleur SiC triphasé 15kVA
Symposium de Génie Electrique, Université de Lorraine [UL], Jul 2018, Nancy, France
A. Hilal, B. Cougo. Optimal Inductor Design and Material Selection for High Power Density Inverters Used in Aircraft Applications
Esars 2016 ( International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles), Nov 2016, Toulouse, France. pp. 1-6
B. Cougo, DH. Tran, G. Segond, A. Hilal. Influence of PWM methods in semiconductor losses of 15kVA three-phase SiC inverter for aircraft applications
EPE (18th International Conference on Electronic Power Engineering), Sep 2017, Varsow, Poland. pp. 1-10
H. Sathler, B. Cougo, JP. Carayon, F. Costa, D. Labrousse. Modeling of Common-Mode Voltage Source for Multilevel Inverter Topologies
2020 International Symposium on Electromagnetic Compatibility – EMC EUROPE, Sep 2020, Rome, Italy. pp.1-3, ⟨10.1109/EMCEUROPE48519.2020.9245681⟩
H. Hoffmann Sathler, L. Nagano, B. Cougo, F. Costa, D. Labrousse. Impact of multilevel converters on EMC filter weight of a 70 kVA power drive system for More Electrical Aircraft
CIPS 2020 – 11th International Conference on Integrated Power Electronics Systems, Mar 2020, Berlin, Germany
B. Cougo, T. Meynard, G. Gateau, L. Morais. Zero Sequences Optimizing Different Criteria for Three-Phase Multilevel Inverters
2018 IEEE Energy Conversion Congress and Exposition (ECCE), Sep 2018, Portland, France. pp.7243-7250, ⟨10.1109/ECCE.2018.8557898⟩
P. Bau, M. Cousineau, B. Cougo, F. Richardeau, N. Rouger. Modeling and Design of High Bandwidth Feedback Loop for dv/dt Control in CMOS AGD for GaN
2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Sep 2020, Vienna ( virtual ), Austria. pp.106-109, ⟨10.1109/ISPSD46842.2020.9170106⟩
P. Bau, M. Cousineau, B. Cougo, F. Richardeau, N. Rouger. Contrôle ultra-rapide et intégré de dv/dt en boucle fermée lors de l’amorçage de transistors à semiconducteurs grand-gap
Symposium de Génie Electrique 2021, Jul 2021, Nantes, France
A. Castelan, B. Cougo, J. Brandelero, D. Flumian, T. Meynard. Optimization of forced-air cooling system for accurate design of power converters
ISIE 2015 (24th IEEE International Symposium on Industrial Electronics), Jun 2015, Buzios, Brazil. pp.367 – 372, ⟨10.1109/ISIE.2015.7281496⟩
A. Hilal, B. Cougo, T. Meynard. Characterization of High Power SiC Modules for More Electrical Aircrafts
IECON 2016 (42nd Annual Conference of IEEE Industrial Electronics Society), 2016, Firenzi, Italy. pp. 1087-1092
P. Bau, M. Cousineau, B. Cougo, F. Richardeau, D. Colin et al.A CMOS gate driver with ultra-fast dV/dt embedded control dedicated to optimum EMI and turn-on losses management for GaN power transistors
2018 14th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME), Jul 2018, Prague, France. pp.105-108, ⟨10.1109/PRIME.2018.8430331⟩
P. Bau, M. Cousineau, B. Cougo, F. Richardeau, N. Rouger. CMOS Active Gate Driver for Closed-Loop d v /d t Control of GaN Transistors
IEEE Transactions on Power Electronics, Institute of Electrical and Electronics Engineers, 2020, 35 (12), pp.13322-13332. ⟨10.1109/TPEL.2020.2995531⟩
A. Castelan, B. Cougo, S. Dutour, T. Meynard. 3D Analytical Modelling of Sink Heat Distribution for Fast Optimisation of Power Converters
Electricmacs 2017, Jul 2017, Toulouse, France. pp.296-307
V. Dos Santos, N. Roux, B. Revol, B. Sareni, B. Cougo et al. Unshielded Cable modeling for Conducted Emissions Issues in Electrical Power Drive Systems
EMC Europe 2017, Sep 2017, Angers, France. pp. 1-6
B. Cougo, H. Schneider, T. Meynard. High Current Ripple for Power Density and Efficiency Improvement in Wide Bandgap Transistor-Based Buck Converters
IEEE Transactions on Power Electronics, Institute of Electrical and Electronics Engineers, 2015, 30 (8), pp.4489-4504. ⟨10.1109/TPEL.2014.2360547⟩
A. Castelan, B. Cougo, S. Dutour, T. Meynard. Optimisation de dissipateurs à ailettes pour des convertisseurs utilisant des composants puissance discrets
Symposium de Génie Electrique, Université de Lorraine [UL], Jul 2018, Nancy, France
V. Dos Santos, B. Cougo, N. Roux, B. Sareni, B. Revol et al. Trade-off between Losses and EMI Issues in Three-Phase SiC Inverters for Aircraft Applications
EMC 2017 (Electromagnetic Compatibility, Signal and Power Integrity), Aug 2017, Washington, United States. pp. 1-6
B. Taghia, B. Cougo, H. Piquet, D. Malec, A. Belinger et al. Overvoltage at motor terminals in SiC-based PWM drives
Mathematics and Computers in Simulation, Elsevier, 2018, 158, pp.264-240. ⟨10.1016/j.matcom.2018.09.009⟩
B. Taghia, B. Cougo, H. Piquet, D. Malec, A. Belinger et al. Advanced analysis of transient overvoltage in electromechanical chain fed by SiC inverter
Electrimacs 2017, Jul 2017, Toulouse, France. pp.0