Modeling and Design of a Zero-Voltage Switching Battery Charger for Photovoltaic Applications

A novel solar-fed quasi-resonant battery charger operating in the Discontinuous Voltage Mode (DVM) is proposed and designed to achieve a high efficiency on a wide range of operating powers. The converter design procedure ensures the achievement of the Zero Voltage Switching of its MOSFETs on a wide range of operating conditions, thus reducing the switching losses. An analytical model of the converter operation and its static characteristic in its two operating modes is provided. A step-by-step design procedure for the converter is proposed for given battery and PV panel specifications. Measurements on a 100 W, 12 V-output prototype validate the accuracy of the modelling and highlight a high efficiency always above 90.9% with the input voltage ranging from 26.5 V and 28.5 V and an input power in the wide 20 W-100 W range.