The Analysis of Current Sharing Effect for Two-Unit Paralleled Common Capacitor <i>LLC</i> Resonant Converter
Wei Tang, Hongliang Wang, Xiaonan Zhu, Wenhui Mo, Wenyong Gao, Xiumei Yue
Abstract
A passive current sharing method for paralleled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters is proposed in this article, and the current sharing effect of paralleled common capacitor <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter is analyzed. The passive current sharing method is achieved by adding coupled impedance between the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters, and the coupled impedance can be inductive, capacitive, infinitely small, and infinitely large. Among them, it is traditional paralleled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter without current sharing ability when the coupled impedance is infinitely large. First, the mathematical model of paralleled common capacitor <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter with coupled impedance is built based on fundamental harmonic analysis. Second, according to the mathematic model, the current sharing effect of the paralleled common capacitor <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter of different coupled impedance under different parameter difference is analyzed, it is easy to see the current sharing effect is improved after the couple impedance is added, and in general, inductive coupled impedance has a better current sharing effect for paralleled common capacitor <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter. Last, the theoretical analysis results are verified by simulation and experimental results.