An MPPT technique for unshaded/shaded photovoltaic array based on transient evolution of series capacitor

摘要

For maximum power point (MPP) application, the transient evolution of capacitor can be exploited to examine the power-voltage (P-V) characteristics of a photovoltaic (PV) array. This method is simple and inexpensive. In addition, it can be implemented on any array size whether un-shaded or partially shaded. This paper presents a new MPPT technique that scans the P-V curve of PV array with a series capacitor (C-scan) through a unique H-bridge architecture. The proposed technique employs a simple algorithm, which controls the H-bridge to scan the P-V curve in two sequences: (1) during charging of capacitor, and (2) during discharging of capacitor. The proposed MPPT neither requires the isolation of PV array from load nor executes power loss during checking of P-V curve. The effects of input capacitor (CO of converter during scanning of P-V curve are comprehensively discussed, and then the correct sizing of C-scan according to array size is explained with a design example. A comparative analysis of different MPPTs in the context of tracking ability, dynamic, and steady state efficiencies is presented. This analysis highlights the advantage of proposed technique over other MPPTs. Finally, the fundamental operation of proposed MPPT is verified through experimental results. (C) 2017 Elsevier Ltd. All rights reserved.