PV power conditioning system with LLC resonant converter in DCM

This paper presents a DC-DC power conditioning system for photovoltaic (PV) panels. A series loaded resonant converter with galvanic isolation, also known as an LLC resonant converter is used to interface PV arrays to the batteries within an energy management system. The LLC converter is operated in discontinuous conduction mode (DCM) in order to minimize the switching losses, even with the wide input voltage range. This mode of operation also makes LLC converters easy to parallel, which is desirable when multiple micro-converters are used instead of a centralized inverter. A perturb and observe maximum power point tracking (MPPT) algorithm is implemented with just a voltage sensor. Its performance is compared to that of an MPPT algorithm using both voltage and current feedback. In this paper the PV power conditioning system is designed and implemented in the laboratory. Experimental measurements demonstrate the power conditioning system functionality.