Analysis of the Characteristics in Wide‐Input High Step‐Up LLC Resonant Converter

ABSTRACT The widely used LLC resonant converter is being focused on for high‐voltage applications such as renewable energy systems. However, the analysis methods of the high‐gain resonant network are usually unable to simultaneously balance both aspects, the accuracy and the simplicity, due to the complex resonant process, bringing difficulties in engineering practice as reference. Aiming at exploring the detailed step‐up principles of the resonant network, this paper gives a more accurate model based on the classical fundamental harmonic analysis to improve its practical utilization, reanalyzes the operating characteristics combined with the time domain analysis, proposes the resonant power analysis, and draws some conclusions previously neglected, for example, the characteristic frequencies related to the maximum gain and the boundary of soft‐switching and hard‐switching are actually unequal. A 3000 V‐output experimental prototype is built to verify the theoretical analysis and prove its practicality with a high‐ratio transformer, whose output power is 500–3000 W.