Dual-Input Single-Resonant Tank LLC Converter with Phase Shift Control for PV Applications

Abstract

This paper proposes a dual-input LLC resonant converter that interfaces with two photovoltaic (PV) panels. The topology is a dual half-bridge LLC circuit with four active switches. This topology allows the two sources to share the same resonant tank for transferring energy to the load without the need for additional circuit components. A phase-shift pulsewidth modulation (PWM) control is employed to implement independent maximum power point tracking (MPPT) for each PV panel. Independent MPPT is achieved by varying the PWM phase shift of each source. Zero-voltage-switching is realized in all switches over the entire range of source voltage and load conditions. In addition, voltage stress across switches does not exceed the input PV voltage. A 500-W prototype was built to demonstrate the performance of the proposed topology. The input voltage range was selected between 25 and 50 V with an output voltage regulated at 220 V dc. Experimental results show that the proposed converter can achieve the peak efficiency of 95.8% while maintaining a wide input voltage range and implementing MPPT for each PV panel.