Design and implementation of multiple maximum power point trackers for multi-string PV panels in DC distribution systems

This paper presents design and implementation of multiple maximum power point trackers (MPPTs) with wide input voltage variation for dc distribution systems. The topology of the proposed MPPT combines buck and boost converters to accommodate PV input voltage from 0 V to 850 V. The control algorithm for tracking maximum power points is based on a “perturbation and observation” method. The proposed MPPT can on-line check the input configuration of PV-panel strings to determine the current for maximum power calculation. In the paper, operational principle, analysis and design of the proposed MPPT configuration and mode transition will be first presented. Flowcharts of the control algorithm include perturbation and observation method and on-line PV-panel string configuration check will be then explained. Experimental results obtained from three-string MPPTs with the maximum power of 10 kW have verified its performance and feasibility.