Abstract:In this paper, a fuzzy-logic-control (FLC) based maximum power point tracking (MPPT) algorithm for photovoltaic (PV) systems is proposed. The power variation and output voltage variation are chosen as inputs of the proposed FLC, which simplifies the calculation. Compared with the conventional perturb and observe (P&O) method, the proposed FLC-based MPPT can simultaneously improve the dynamic and steady state performance of the PV system. To further improve the performance of the proposed method, an asymmetrical membership function (MF) concept is also proposed. Two design procedures are proposed to determine the universe of discourse (UOD) of the input MF. Comparing with the proposed symmetrical FLC-based MPPT method, the transient time and the MPPT tracking accuracy are further improved by 42.8% and 0.06%, respectively.

Nowadays, commercial lithium-ion (Li-ion) batteries are playing important roles as supplies for mobile phones, laptop computers and other electronics. In order to maximize the performance of Li-ion batteries, advanced charger is required. The main objective of an advanced battery charger includes short recharge times, high charging efficiencies and improved battery cycle life. This paper presents the design and implementation of a dsPIC-based fuzzy five-step Li-ion battery charging system. To obtain the optimal charging performance for the Li-ion battery, fuzzy-control-based fivestep charging algorithm and a simple power stage is used in the proposed system. Using this control, the performance of the proposed system can be improved.In addition to the hardware, a graphical user interface is also presented in this paper. According to the experimental results, the proposed charger is capable of charging the Li-ion batteries with higher efficiency and lower temperature rise.

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