An efficient and low-cost DMPPT approach for photovoltaic submodule based on multi-port DC converter

Abstract

Solar energy is one of the most promising energy types, but photovoltaic (PV) mismatches have several negative effects. Finding an efficient and low-cost method to reduce or eliminate the power loss caused by the mismatch in PV power generation systems is necessary. In this paper, we propose a PV submodule-distributed maximum power point tracking (DMPPT) scheme based on a multi-port DC converter. In-depth analysis and research are performed on the PV model and mismatch characteristics, the PV module voltage equalization (VE) strategy, and implementation with the multi-port buck–boost converter. We discuss the trade-off between true DMPPT and VE on control overhead and tracking accuracy, and a detailed derivation is created to illustrate the differences between them. The VE can reduce the cost and complexity of the system at the expense of a small PV energy capture. The proposed implementation reduces the number of semiconductor components and current sensors, which is conducive to the integrated design of the hardware. A prototype based on a multi-port buck–boost converter for a 36 V/200 W PV module was designed and built. The feasibility and progress of the proposed scheme were verified through experiments.