Soft-switching techniques for medium-voltage isolated bidirectional DC/DC converters in solid state transformers

Soft switching techniques are very attractive and often mandatory requirements in medium-voltage and medium-frequency applications such as solid state transformers. The effectiveness of these soft switching techniques is tightly related to the dynamic behavior of the internal stored charge in the utilized semiconductor devices. For this reason, this paper analyzes the behavior of the internal charge dynamics in high-voltage semiconductors, giving a clear base to understand the previously proposed zero-current-switching techniques for IGBT-based resonant dual-active-bridges. From these previous approaches, the two main concepts that allow switching loss reduction in high-voltage semiconductors are identified: 1) shaping of the conducted current in order to achieve a high recombination time in the previously conducting semiconductors and 2) achieving ZVS in the turning-on device. The means to implement these techniques in a triangular current mode dual-active-bridge converter together with the benefits of the proposed approaches are analyzed and experimentally verified with a 1:7 kV IGBT-based NPC bridge. Additionally, the impact of the modified currents in the converter's performance are quantified in order to determine the benefits of the introduced concepts in the overall converter.

[1]  M. Steiner,et al.  Medium frequency topology in railway applications , 2007, 2007 European Conference on Power Electronics and Applications.

[2]  J.W. Kolar,et al.  A comparative evaluation of isolated bi-directional DC/DC converters with wide input and output voltage range , 2005, Fourtieth IAS Annual Meeting. Conference Record of the 2005 Industry Applications Conference, 2005..

[3]  Staffan Norrga,et al.  New topology for more efficent converters for future offshore wind farms , 2004 .

[4]  J. W. Kolar,et al.  1 Megawatt, 20 kHz, isolated, bidirectional 12kV to 1.2kV DC-DC converter for renewable energy applications , 2010, The 2010 International Power Electronics Conference - ECCE ASIA -.

[5]  J. Taufiq,et al.  Power Electronics Technologies for Railway Vehicles , 2007, 2007 Power Conversion Conference - Nagoya.

[6]  Nikolaus Schibli.  Symmetrical multilevel converters with two quadrant DC-DC feeding , 2000 .

[7]  Hans-Peter Nee,et al.  On Dynamic Effects Influencing IGBT Losses in Soft-Switching Converters , 2011, IEEE Transactions on Power Electronics.

[8]  Steffen Bernet,et al.  Characterization of a 6.5 kV / 500A IGBT module in a series resonant converter , 2011, 2011 IEEE Energy Conversion Congress and Exposition.

[9]  L. Heinemann,et al.  The universal power electronics based distribution transformer, an unified approach , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[10]  Harry Reinold.  Characterization of Semiconductor Losses in Series Resonant DC-DC converters for High Power Applications using Transformers with Low Leakage Inductance , 1999 .

[11]  B Piepenbreier,et al.  High voltage IGBTs and medium frequency transformer in DC-DC converters for railway applications , 2010, SPEEDAM 2010.

[12]  Staffan Norrga,et al.  New topology for more efficient AC/DC converters for future offshore wind farms , 2004 .

[13]  Jun Wang,et al.  Smart grid technologies , 2009, IEEE Industrial Electronics Magazine.

[14]  Frederick Kieferndorf,et al.  Power Electronic Transformer Technology for Traction Applications – An Overview , 2012 .

[15]  V. Parthasarathy,et al.  A study of the internal device dynamics of punch-through and nonpunch-through IGBTs under zero-current switching , 1997 .

[16]  Michael Weiss,et al.  Design, implementation and performance of a modular power electronic transformer (PET) for railway application , 2011, Proceedings of the 2011 14th European Conference on Power Electronics and Applications.

[17]  Drazen Dujic,et al.  Laboratory scale prototype of a power electronic transformer for traction applications , 2011, Proceedings of the 2011 14th European Conference on Power Electronics and Applications.