Fuzzy Logic Based Maximum Power Point Tracking Scheme for PV System Using P-V and I-V Characteristics

This paper presents a fuzzy logic-based maximum power point tracking (FL-MPPT) scheme for photovoltaic (PV) systems using P-V and I-V characteristics of the PV source. Conventional FL-MPPT schemes given in the literature are based on P-V characteristics. The fuzzy input variables used in conventional schemes are typically designed using P-V characteristics at standard test conditions (STC). So, for the environmental conditions away from STC, their performance detracts typically at low irradiance. This is mainly attributed to the flatness of the P-V characteristics. To overcome this issue, FL-MPPT uses both P-V and I-V characteristics for tracking maximum power point (MPP). Usage of the I-V characteristics improves the performance MPPT scheme for all irradiance and temperature. It not only improves the transient racking period but also has low power ripple during steady state. For the validity of the proposed method, MATLAB/Simulations results are presented for gradual and step change in environmental conditions and compared with the conventional FL-MPPT scheme.