Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Interleaved current source inverters for high power PV converters prototyping

Département des Technologies Solaires (LITEN)



Conventionally, systems for converting electrical energy in the photovoltaic domain are voltage inverter type structures [4] - [7]. In this case, the conversion chain of the photovoltaic energy is composed of two stages: a DC-DC converter followed by a voltage inverter (VSI). These voltage source topologies have short-term disadvantages (link capacitor lifetime problems) [5], [8], [9] and relatively low efficiency (due to a double conversion) [5]. As an alternative solution, the current inverter (CSI) structure can be used. Among the advantages of the CSI structure, can be listed: -A reduction in the number of power components, due to the conversion of energy with a single conversion stage [5] -A longer converter lifetime (compared to conventional structures) due to the suppression of the link capacitor [5], [8], [9] and a voltage in the blocked state seen by the switches lower [11] -Integration of natural short-circuit protection On the other hand, the CSI topology has the following disadvantages: -Relatively high conduction losses due to the series connection of devices (MOSFET + Diode) [4], [6] -Special protection requirements for AC and DC sides [4] For the CSI topology, one possible way to overcome the disadvantage of high switching losses is to use Wide bandgap devices (WBGs). Specifically, SiC semiconductors, because of their higher voltage ranges. The LSPV is currently working on: -The characterization of WBG semiconductors in 1.7kV blocking voltage -The design and building of a 100 kW CSI (using custom modules) -The characterization of the efficiency of the converters by calorimetric methods -The study and building of a high power multi-level CSI converter The subject of the thesis is the logical continuity of this work with an important part relative to the control of the structure, the interleaving of the blocks, the reduction of the size of the input inductor. [1] Jäger-Waldau, A. (2016). PV Status Report 2016. JRC Science for Policy Report (Publications Office of the European Union, 2016). [2] Photovoltaics report. Fraunhofer Institute for Solar Energy Systems-ISE, Freiburg, November 2016. Retieved May 2017. [3] BURGER, Bruno. Power Electronics for Photovoltaics. 2015. [4] Sahan, B., Araujo, S. V., Noding, C., & Zacharias, P. (2011). Comparative evaluation of three-phase current source inverters for grid interfacing of distributed and renewable energy systems. IEEE Transactions on Power Electronics, 26(8), 2304-2318. [5] Bülo, T., Sahan, B., Nöding, C., & Zacharias, P. (2007, September). Comparison of three-phase inverter topologies for grid-connected photovoltaic systems. In Proc. 22nd Eur. Photovolt. Sol. Energy Conf. Exhib., Milan, Italy. [6] Martin, J., Bier, A., Catellani, S., Alves-Rodrigues, L. G., & Barruel, F. (2016, May). A high efficiency 5.3 kW Current Source Inverter (CSI) prototype using 1.2 kV Silicon Carbide (SiC) bi-directional voltage switches in hard switching. In PCIM Europe 2016; Proceedings of (pp. 1-8). VDE. [7] Sahan, B., Vergara, A. N., Henze, N., Engler, A., & Zacharias, P. (2008). A single-stage PV module integrated converter based on a low-power current-source inverter. IEEE Transactions on Industrial Electronics, 55(7), 2602-2609. [8] Wang, H., Liserre, M., & Blaabjerg, F. (2013). Toward reliable power electronics: Challenges, design tools, and opportunities. IEEE Industrial Electronics Magazine, 7(2), 17-26. [9] Yang, S., Bryant, A., Mawby, P., Xiang, D., Ran, L., & Tavner, P. (2011). An industry-based survey of reliability in power electronic converters. IEEE Transactions on Industry Applications, 47(3), 1441-1451. [10] Engler, A., et al. "Design of a 200W 3-phase module integrated PV inverter as part of the European project PV-MIPS." Proceedings of the 21st European Photovoltaic Solar Energy Conference and Exhibition, Dresden, Germany. 2006. [11] Felgemacher, C., Araujo, S. V., Noeding, C., & Zacharias, P. (2016, May). Benefits of increased cosmic radiation robustness of SiC semiconductors in large power-converters. In PCIM Europe 2016; Proceedings of (pp. 1-8). VDE. [12] Rashid, M. H. (2010). Power electronics handbook: devices, circuits and applications. Academic press.

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