Application Of Push-pull Full-bridge Converter In Photovoltaic System Research

Due to global environmental issues and national energy development strategyadjustment，the Photovoltaic systems has been developed rapidly. In stand-alonePhotovoltaic systems, the storage link is essential. Aming at the applications of largeinput current and high voltage transfer ratio situation, a Push-pull Full-bridgeBidirectional DC/DC Converter is researched in this paper.Fisrtly, this paper introduces development and application background ofBidirectional DC/DC Converter, Proposed the current-fed push-pull full-bridgebidirectional DC/DC converter. There are two operating modes（1）Boost mode：battery discharge，through the push-pull circuit and high-frequency transformer forthe battery voltage boost.（2）Buck mode：Battery charge, through the full-bridgecircuit and high-frequency transformer for the DC bus voltage buck. This paperdescribes the working principle of the two models and simulation waveforms. Thenraised three key questions used in stand-alone PV system current-fed push-pullfull-bridge bidirectional DC/DC converter:(1) The startup and shutdown;(2) Pushside voltage spikes;(3) High-frequency transformer magnetic bias and magnetic fluxleakage. Detailed study of the voltage spikes and the push-pull side.Analyzed the reasons of the spike voltage generated on the push-pull side, andproposed three solutions which are RCD, LCD, the active clamp. Studied the workingprinciple and the advantages and disadvantages of the three solutions and Theeffects of synchronous rectification mode voltage spikes. Finally developed aconverter of1000W, give a detailed hardware design process and experimentaloscillogram.