Photovoltaic power-increment-aided incremental-conductance maximum power point tracking using variable frequency and duty controls

This paper presents a smart photovoltaic (PV) power-increment-aided incremental-conductance MPPT (PI-INC MPPT) using either variable-frequency constant-duty control (VFCD) or constant-frequency variable-duty control (CFVD). The tracking of PI-INC MPPT with reference to a threshold tracking zone (THZ) is implemented by a two-step approach, a power-increment (PI) coarse-tracking along P_pv-V_pv curve and an incremental-conductance (INC) fine-tracking along I_pv-V_pv curve. An ambiguous detection using INC MPPT, in the flat-and-low conductance region of I_pv-V_pv curve, will not be arisen by using the PI coarse-tracking that enriches the PI-INC MPPT fast tracking along P_pv-V_pv curve with obvious detection against the potential tracking delay. Modeling and analysis of two typical PV power converters, using VFCD and CFVD controls, which implement the tracking of the PI-INC MPPT, are respectively addressed. The effectiveness of the tracking behavior of PI-INC MPPT by the two power converters in comparison with that using conventional INC-MPPT is assessed through the experimental tests.