Quad-Input Single-Resonant Tank LLC Converter for PV Applications

A quad-input LLC converter for photovoltaic (PV) application is proposed in this paper. In this topology, a single LLC resonant tank is utilized to transfer the energy from four PV panels to the output by using two Y configurations of switches. The PWM generation of all these switches depends on switching frequency and three phase shifts. An MPPT control strategy based on Perturb and Observe (P&O) method has been proposed in this paper to ensure the independent maximum power point tracking (MPPT) for all PV panels. The zero-voltage switching (ZVS) across all the switches for a wide input range and load variations is achievable with this topology. A detailed mode-by-mode analysis followed by the switching waveforms has been illustrated, which led to the gain equation derivation. In that context, a state plane trajectory has also been drawn according to the various modes of LLC topology. Finally, a 500W prototype has been built and tested to verify the operation of the converter. The achieved peak efficiency of the converter is 94.3% when all four PV panels track their maximum power point (MPP) individually.