The Analysis of Current Sharing Effect for Two-Unit Paralleled Common Capacitor LLC Resonant Converter

A passive current sharing method for paralleled LLC resonant converters is proposed in this article, and the current sharing effect of paralleled common capacitor LLC resonant converter is analyzed. The passive current sharing method is achieved by adding coupled impedance between the LLC resonant converters, and the coupled impedance can be inductive, capacitive, infinitely small, and infinitely large. Among them, it is traditional paralleled LLC resonant converter without current sharing ability when the coupled impedance is infinitely large. First, the mathematical model of paralleled common capacitor LLC 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 LLC 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 LLC resonant converter. Last, the theoretical analysis results are verified by simulation and experimental results.