Phase Shift, Duty Cycle and variable Frequency Control of a Full-Bridge DC-DC Converter for Two Solar PV Panels

Abstract

Renewable energy resources are becoming the future of power generation with a particular focus on harvesting the solar energy found in abundance on earth’s surface. Different power converter topologies are used for energy conversion that allow PV’s to connect in different configurations for the transfer of power. Differential power processing (DPP) has the advantage of high efficiency, but the limitation of such architectures exist in the complexity of operation with the increasing number of PV panels.

This thesis presents a novel DC-DC converter topology for multiple PV panels. The proposed topology provides an individual maximum power point tracking (MPPT) of the series connected PV panels by a differential current path introduced by an auxiliary inductor. The MPPT of the PV panels is achieved by controlling the three converter parameters: phase shift control to regulate the panel PV1 voltage, duty cycle to control the differential current through the auxiliary inductor, and lastly the control of converter’s switching frequency for increased efficiency under light mismatch condition of the PV panels. Controlling the differential current of the auxiliary inductor, also helps in achieving ZVS for the entire load range and eliminates the need for any additional active switches to achieve MPPT for the PV panels. Thus, the simple structure and the ability to achieve ZVS of the proposed topology make it an excellent and cost-effective solution for high frequency solar applications.