Implementation of INC MPPT and CV Charging Using LLC Resonant Converter for Solar Streetlight System

摘要

Most existing stand-alone photovoltaic (PV) power systems employ pulse-width-modulated (PWM) DC-DC converters for maximum power point tracking (MPPT) and battery charging control. However, PWM converters experience high switching loss and high electromagnetic interference when operating at high frequency. Therefore, this paper presents an incremental conductance (INC)-based MPPT with constant voltage (CV) charging using LLC resonant converter for stand-alone solar streetlight system. INC MPPT maximizes the PV power generation while CV charging ensures good battery charging characteristics. Both the INC MPPT and CV charging are implemented in an algorithm using an Arduino Uno board. Detailed design procedure as well as extensive design considerations for a 100 W prototype LLC resonant converter are presented. Experimental results show good MPPT performance under various environmental conditions such as sudden rise or sudden drop of incident irradiance. Furthermore, the system shows exceptional robustness in toggling between INC MPPT mode and CV charging mode depending on the environmental conditions. The converter displays excellent switching operation by achieving primary-side zero voltage switching and secondary-side zero current switching for the entire design range.