A Passive Current Sharing Method for Two-Phase Common Inductor LLC Resonant Converters and Mathematical Analysis of Current Sharing Effect

A passive current sharing method for a two-phase common inductor LLC resonant converter is proposed in this article, and the relative mathematical analysis of current sharing error is carried out. The concept of a common inductor comes from the introduction of coupled impedance, where the resonant inductors of two phases are connected, which means that the separated two phases are coupled by an additional impedance. Obviously, there are four cases of coupled impedance, which are infinite impedance, infinitely small impedance, inductive impedance, and capacitive impedance, and they are all analyzed in the article. In addition, for different inductor and capacitor parameter differences, the two-phase common inductor LLC resonant converter has different current sharing characteristics, and there is an optimal solution for different coupled impedance for each difference. However, under each parameter difference, when the coupled index g is a negative number, there is generally a better current sharing effect. At last, simulation and experimental results have proved the correctness of the theoretical analysis.