Ultra-Fast MPPT for Residential PV Systems With Low DC-Link Capacitance and Differential Power Processing

Tracking efficiency, cost, and reliability are important factors when selecting photovoltaic (PV) architectures and converter topologies. PV systems require power converters to maximize power extraction, for which dc–dc converters are a common choice. Differential power processing (DPP) architectures can achieve higher efficiencies and lower cost by reducing the amount of power passing through these converters, while still providing maximum power point tracking (MPPT) capabilities. Single-phase grid connected PV systems, which are the most popular choice in residential applications, require a large capacitance in the dc bus to minimize the voltage ripple caused by double-line pulsating power, impacting the cost and reliability of the system. This work introduces a new MPPT mode of operation for flyback converters in DPP architectures. The proposed MPPT method shows extremely fast dynamic performance and it is capable of maximizing the power extraction even for extreme variations in the bus voltage. In this way, the method enables a significant reduction in the dc bus capacitance, reducing costs, and facilitating the use of ceramic capacitors, while maintaining excellent tracking efficiency. The analysis incorporates comprehensive models that characterize the large-signal dynamic behavior of ideal and nonideal flyback converters, and it is supported by detailed mathematical procedures. The system performance behavior, and limits are validated through simulation and experimental results.