Five-Phase <i>LLC</i> Resonant DC/DC Converter Utilizing <i>CLC</i> Filter for Current Sharing
Jianing Wang, Wei Pei, Jiawen Hu, Shuang Zhao, Jiacai Zhuang
Abstract
Multiphase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters are extensively used in the high-power scenarios. Compared with the common three-phase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters, a five-phase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> (FPLLC) resonant converter can operate at higher power density with reduced current ripple, yet the current imbalance issue induced by the passive component tolerance is aggregated. In this article, the FPLLC converter topology is introduced. Via the current phasor diagram and time-domain analysis of resonant current with large component tolerance, an analytical model for unbalanced currents of the worst case is deduced. In addition, a current sharing method utilizing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> output filter is proposed. The high-impedance commutation path introduced by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> parallel resonance tank of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> filter can suppress the unbalanced current. Combining with the derived unbalanced current in the worst case, the design process of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> filter is presented in details. Both the analytical model of resonant current in the worst case and the current sharing functionality of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> filter are validated with simulation and experimental study.