Research On High Frequency Isolated Three-level Bi-directional DC/DC Converter

The high frequency isolated bi-directional DC/DC converter of the cascadedmulti-level converter without line-frequency transformer is taked as the researchobject, and the topology which based on the structure of half-bridge three-level ispresented. To study the high frequency isolated bi-directional DC/DC converter, thetwo main structure which are the dual half-bridge three-level structure and the hybridstructure of half-bridge three-level add H-bridge are recearched. The paper analyzedthe working principles and working modes of the two topology in detail, researchedthe power flow characteristics, soft-switching conditions, reactive power and backflow power characteristics based on the traditional single phase-shift modulationstrategy, the proposed of new dual phase-shift modulation strategy is not only enlargethe range of the soft-switching, but also achieved to decrease reactive power and backflow power. At the same time, the article also built the mathematical model of thehigh frequency isolated dual half-bridge three-level bi-directional DC/DC converterand designed a controller as well as developed a small experimental platform.Simulation and experiment proves the validity of the researching findings.