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Analysis of Unified Output MPPT Control in Sub-Panel PV Converter System

Fig. 1. Unified MPPT control diagram.
Photovoltaic (PV) systems frequently suffer disproportionate impacts on energy production due to mismatch cases. To remedy this, academia has proposed a distributed maximum power point tracking (MPPT) solution which has been implemented commercially. Taking the trend of the "distributed MPPT" concept a step further, this paper discusses and analyzes an MPPT converter that connects to each PV cell string, called a subpanel MPPT converter (SPMC), to better address the real-world mismatch issues. The SPMC system with a unified output MPPT control structure is also proposed in order to reduce the cost and simplify the distributed MPPT system. The proposal saves A/D units, current sensors and MPPT controllers on the premise of guaranteeing that all the PV cell strings work at their individual maximum power state regardless of the mismatch case. This is favorable for further integration and makes the whole SPMC system less expensive and easier to realize., The effectiveness of this proposal has been confirmed experimentally.

Fig. 2. Comparison of different structures.