A Multi-Degree-of-Freedom Differential Power Processing Architecture for Photovoltaic System

To address the efficiency loss caused by the need for an additional central converter in traditional photovoltaic-isolated port architecture, the concepts of differential power processing (DPP) and series-connected partial power processing are introduced, and then a multi-degree-of-freedom differential power processing (MF-DPP) architecture for photovoltaic system is proposed. In the proposed architecture, the auxiliary converter is introduced to be paralleled with the DPP converters and connected in series with the PV modules, so that the bus port can directly connect the loads with specific voltage requirements and the efficiency of the entire system can be improved. A control algorithm for the new architecture is also proposed, which can simultaneously achieve maximum power point tracking for PV modules and least power point tracking for the total power processed by the DPP converters. Finally, a photovoltaic system experimental platform is built to verify the effectiveness of the proposed architecture and control algorithm. The experimental results show that the proposed architecture can effectively improve system efficiency under mismatched power conditions.