Design and analysis of a dual-input single-resonant tank LLC converter for PV applications

This paper proposes a dual-input LLC resonant converter that interfaces with two 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 pulse width 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 (ZVS) 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 V to 50 V with an output voltage regulated at 440 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.