Modeling and Design of the LLC Resonant Converter Used as a Solar-Array Simulator

The LLC resonant converter has been used to implement a solar-array simulator with high-efficiency and fast-response features. In this paper, its small-signal model is derived based on the extended describing function concept. The corresponding frequency response can be easily obtained from IsSPICE simulation of the equivalent circuit model. The derived model is matching with the measured results very well. Furthermore, a solar-array simulator with closed-loop control is designed according to the derived small-signal model. The experimental measurements have really proved that high-efficiency and fast-transient responses can be achieved in the system. The output voltage and output current can be adjusted simultaneously to match the electrical characteristics of photovoltaic output.