Modular subpanel photovoltaic converter system: Analysis and control

A modular plug-and-play photovoltaic (PV) converter system for portable PV applications is proposed. Small subpanel of PV cells have individual dc/dc converters performing distributed maximum power point tracking. The dc/dc submodules are connected in parallel to a DC bus. Challenges for the proposed PV system to accommodate diverse types of loads are addressed. Based on scenario analysis, the operating mode and the operating range of the PV system are illustrated. A peer-to-peer control strategy is developed to maintain stable power supply automatically with PV power and/or load power changing. The DC bus is semi-regulated in accordance with different operating scenarios. The presented system features advantages of 1) compatibility of various types of PV subpanels (different chemistry, power levels, and operating characteristics); 2) capability of drawing higher power from mismatched PV subpanels; 3) high reliability due to its parallel structure and peer-to-peer operating mechanism. A prototype of the system has been developed in the lab, and experimental results are provided to verify the method.