A differential current compensation technique for PV systems under partially shaded condition

This paper presents a differential current compensation technique for partially shaded PV string. The proposed technique integrates an input parallel output series (IPOS) configuration of DC-DC flyback converters with distributed digital voltage mode control. PV modules in the string are interfaced with IPOS configuration of flyback converters. Each dedicated converter is regulated at the MPP voltage of corresponding PV module while supplying differential current to the string to keep the string current maximum under partially shaded condition. Dedicated voltage mode controller is implemented using eight bit PIC microcontroller (PIC18F452). A hardware prototype of a PV string is developed by connecting two PV modules in series. The experimental results are demonstrated for static and dynamic operation of IPOS configuration of DC-DC flyback converters under partially shaded condition of PV string.