Study Of Interleaved Dual Buck Full Bridge Three-level Photovoltaic Grid Inverter

Clean and green renewable energy is a new hope to alleviate energy shortage and environmentalpollution problems. Solar energy resource is the most widely distributed in renewable energy sources,so the study of the solar photovoltaic grid-connected inverter system has important theoretical andpractical significance. To meet the requirement of enhancing power levels, quality of grid connectedcurrent and conversion efficiency of the inverter in solar photovoltaic grid connected inverter system.The interleaved dual buck full bridge three-level photovoltaic grid inverter system has been studiedand analyzed deeply in this paper.Firstly, the overall program design of the system is proposed. Detailed studies and discussesabout the defects of the common full bridge grid inverter and dual buck full bridge three-level gridinverter are carried out. The interleaved dual buck full bridge three-level inverter is adopted as themain circuit topology structure and the working principle of it is introduced in detail. Current loop PIregulator strategy is chosen as closed-loop control strategy of the inverter. A specific frequencydoubling unipolar SPWM modulation method is adopted after analyzing several ways of SPWM inthe actual working situation and the interleaved output current of the system is analyzed. Simulationsare also carried out to verify the feasibility and the theoretical analysis of this design in Saber.Secondly, the detailed designs of various modules of hardware and software in the system arecarried out. Hardware circuit part of the system mainly includes main circuit, output filter circuit,auxiliary power supply circuit, phase-locked control circuit, signal sampler and conditioner, drivercircuit, protecting circuit, closed-loop control circuit while the software part includes initialized unit,square-wave signal generation unit, display unit, signal sampling unit and protection unit.Finally, comprehensive experiments have been carried out on the prototype. The prototype worksstability with high conversion efficiency and preferable dynamic performance. Each performanceindex of the prototype meets the requirements of the design. All the test results verify the correctnessof the theoretical analysis and simulation results about the system.