Time Domain Analysis and Gain Curve Modeling of Fractional-Order Full-Bridge LLC Resonant Converter

This article adopts fractional calculus and its Laplace transform to model and analyze the fractional-order full-bridge LLC resonant converter (FO-FBLLC), which aims to extend the topology to fractional-order domain and construct a FO dc model of FO-FBLLC. In this article, a generalized mode analysis is presented, which can provide highly accurate prediction on resonant current and voltage behavior and the dc gain characteristic. Different from traditional integer-order FB-LLC, the operation modes of FO-FBLLC are not only affected by load, frequency and gain conditions, but also by the order of components. Therefore, the operating modes boundary conditions and power loss analysis of fractional-order components are discussed and illustrated. Based on the fractional-order model, a recommended design procedure of FO-FBLLC is presented. Moreover, fractional-order components are constructed and tested based on Oustaloup approximation method. The theoretical analysis of FO model, dc gain curve, mode boundary conditions and design procedure are all demonstrated and validated with high accuracy in simulation results. Finally, an experimental prototype is built to verify the analysis.