Photovoltaic Power-Increment-Aided Incremental-Conductance MPPT With Two-Phased Tracking

Abstract

This paper presents a two-phased tracking that forms a photovoltaic (PV) power-increment-aided incremental-conductance (PI-INC) maximum power point tracking (MPPT) to improve the tracking behavior of the conventional INC MPPT. The PI-INC MPPT performs, using either variable-frequency constant-duty control (VFCD) or constant-frequency variable-duty control (CFVD), with reference to a collectively called threshold-tracking zone (TTZ), beyond which a power-increment (PI) tracking along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> -V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> curve executes and within which an INC tracking along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> -V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> curve toward maximum power point (MPP) does. Delay tracking due to ambiguous conductance-increment detection in the flat portion of the left-hand side of the MPP along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> -V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> curve will not appear in the PI-INC MPPT by using the PI tracking with clear and correct power-increment detection along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> - V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> curve. In addition, the merit of INC MPPT to accurately track against the random solar insolation change still retains in the PI-INC MPPT that uses INC tracking toward MPP along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> -V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pv</sub> curve when tracking in the TTZ. Modeling and analysis of two typical PV power converters with VFCD and CFVD controls are addressed for implementing the tracking of the PI-INC MPPT in design and experiment. The tracking behavior of PI-INC MPPT and the conventional INC MPPT is assessed and compared through elaborate experimental tests.