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High power multilevel converters and related optimized control

by Agnès GP - published on , updated on

Research developed at this topic concerns the design of original architectures high power converters (from hundreds of kW to hundreds of MW) to ensure high quality waveform (low THD) and high energy efficiency. The search for candidate topologies is systematically performed taking into account specific constraints related to the load, to the available power source and also to the application. The methodological approach is based on combinations of associations (imbricated in series, superposed in parallel, direct parallelized, magnetic coupled, ...) of switching cell to exploit the best features of modern semiconductors (Si and SiC Medium and High Voltage) in order to achieve the desired voltage and/or current levels. New complex topologies with improved performance have been put foward and patented. However, they require a control strategy adapted to regulate the internal state variables with high temporal dynamics (floating voltages, differential currents which are images of the magnetic flux). This can be done by exploiting the additional degrees of freedom (redundancy in the switch states) of each new developed structure. Thus, the use of advanced digital technology allows the joint design of the modulation (multilevel PWM) and the control of state variables at a time scale up to the switching period. These aspects are particularly addressed in the framework of the “transversal” Action IEP (Power Electronics Integration) in collaboration with the research group Codiase of LAPLACE.

3-level 3-phase inverter topologies using two inverters coupled by Intercell Transformers (VDC=300V, AC=20ARMS) [PhD: A. Leredde, S. Solano]
Reactive power compensator using PWM AC chopper – 1.2 MVAR - Collaboration with SNCF [2006-2010, PhD: A. Lowinsky]
AC/DC 60kV isolated conversion system (air cooled). S = 200 kVA ; SiC MOSFET and SiC diodes (10 kV). Collaboration with ALSTOM – Transport et PRIMES. [2009-2012, PhD: J. Casarin; ANR Project “CONCIGI_HT”]
Prototype of an AC/DC modular multilevel converter (10kVA-600V). Control using OPAL-RT system. [2011-2013, PhD: N. Serbia – Co-directed by University of Naples]
Strategies for the control of internal and/or external variables of hybrid series-parallel multilevel topologies [2011-2013, PhD: E. Solano]