Analysis and design of a secondary side resonance tank LLC converter for a wide input range grid-connected photovoltaic system

In this paper, the use of a secondary side resonance tank LLC converter in a grid-connected photovoltaic system is suggested. The proposed converter, like a conventional LLC resonant converter, has a resonance tank with three passive components. Hence, it has its advantages such as soft switching and good performance in a wide range of input and load. In this converter, the resonance tank is shifted from the primary side of the transformer to the secondary side. Therefore, the efficiency increases as the current stress in the resonant tank decreases. To show the better performance of this converter than a conventional LLC resonant converter, the converter is designed for a power range of ۳۳۵W. The simulations of the designed converter are done with MATLAB/SIMULINK for both zero voltage switching and zero current switching regions. This converter has similar results in both cases when operating at best conditions. However, when the irradiance is low, in zero voltage switching case, the efficiency is low, and in zero current switching case, despite the appropriate efficiency, its ripple is high. In the best condition, the efficiency of this converter is ۰.۹۶, which is much higher than the conventional LLC resonant converter whose value was ۰.۹۴۳.

Keywords:

secondary side resonance tank LLC converter , grid-connected photovoltaic system , zero voltage switching , zero current switching