There are multiples conditions that lead to partial shading conditions (PSC) in photovoltaic systems (PV). Under these conditions, the harvested energy decreases in the PV system. The maximum power point tracking (MPPT) controller aims to harvest the greatest amount of energy even under partial shading conditions. The simplest available MPPT algorithms fail on PSC, whereas the complex ones are effective but require high computational resources and experience in this type of systems. This paper presents a new MPPT algorithm that is simple but effective in tracking the global maximum power point even in PSC. The simulation and experimental results show excellent performance of the proposed algorithm. Additionally, a comparison with a previously proposed algorithm is presented. The comparison shows that the proposal in this paper is faster in tracking the maximum power point than complex algorithms.

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This paper presents a digitally controlled integrated electronic ballast with dimming and power factor correction features. The control circuit is based on a low-cost PIC16C71 microcontroller where the different strategies for energysaving have been implemented. The ballast is operating in closed loop achieving tight lamp current regulation through a digital Proportional-Integral algorithm. The integrated power stage is based on a frequency-controlled single-switch boost rectifier plus a half-bridge series resonant parallel loaded inverter sharing one power switch. The single-switch boost rectifier works in discontinuous inductor current mode with automatic power factor correction. Detailed analysis of the power stages and experimental results using 42-watt electronic ballast are presented.