A novel adaptive magnetizing inductance control scheme for high-efficiency LLC resonant converter for PV applications

Abstract

In this paper, A novel control scheme of LLC resonant converter is proposed to maximize energy harvest of photovoltaic resources by adapting an integrated transformer with variable magnetizing inductance adaptively. The proposed resonant converter changes its magnetizing inductance according to the PV panel operating condition, and thus it is possible to achieve a minimum circulating energy under wide input voltage range by the appropriate DC gain of the resonant tank. In addition, the proposed method introduces the feedback loop based on the switching frequency to regulate the magnetizing inductance, and as a result, those advantages can be easily obtained in even wide output power levels. The operating principles of the proposed converter and its control structure are explained in detail, and the design example of a 250-W converter is also presented by using the fundamental harmonic analysis. Several simulation results under various conditions of PV source and output power levels are provided in order to verify its effectiveness.