An Improved Photovoltaic Differential Power Processing System Using Bidirectional Boost-Type Converters With Synchronous Switching

In photovoltaic (PV) differential power processing (DPP) systems, bidirectional flyback converters are commonly used because of their isolated structure and bidirectional power-flow capability. However, they have a coupled inductor, often with high leakage inductance that causes high power loss. This work introduces a split-inductor boost converter in combination with conventional boost converters for the PV-to-bus DPP system to replace the conventional flyback converters to achieve higher DPP system efficiency. The proposed PV-to-bus DPP system includes three different topologies of nonisolated boost converters connected together. These bidirectional converters operate in discontinuous conduction mode (DCM), and synchronous switching is utilized to further increase efficiency. To validate the proposed DPP converters, system efficiency was measured at different mismatch levels and compared to the results with flyback converters. At 50% mismatch of one PV substring (in a module of three substrings), the system efficiency reached 92.7%, which was 4.9% higher than when using flyback converters. The implemented split-inductor boost converter had a volume of 72 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> , while the flyback converter had a volume of 141 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> . Overall, this research verifies that using the DPP split-inductor boost converters with DCM synchronous switching has better performance and a smaller overall volume than using flyback converters.