Research And Realization Of A DC-DC Converter Of Three-Level High Efficiency PV Grid-connected Inverter

In face of energy crisis, more and more attention was paid to solar energy which is one of the new energy. Photovoltaic power generation is currently one of the main ways of utilizing solar energy.Small and medium power inverter power is an important part of the independent AC photovoltaic system, whose reliability and efficiency is critical to promote the photovoltaic systems, to use energy effectively and to reduce system cost.Therefore,in order to promote the industry to develop better and faster,national PV experts have been working hard to develop suitable household power inverter.Non-isolated three-level photovoltaic grid-connected inverter transmits electric power from the solar panels to the grid after a DC-DC and DC-AC conversion. This not only eliminates the need for heavy transformer, but also has the advantages of small size, light weight, low cost and high efficiency.This thesis is focused on the design and implementation of transformation of DC-DC in inverter system.The controller uses the combined structure of DSP and CPLD,achieving the digitization of the system and improving the control accuracy. This design uses the improved ZVT-Boost soft-switching converter,analyzes its working principle and selects parameters and models of the main components in the circuit.And verify the correctness of theoretical analysis through simulation and debugging. Experimental results show that the soft-switching of main switch and auxiliary switch are basically realized and the efficiency is99%. In the paper,a photovoltaic cell simulation model is builded to verify the impact of temperature and light intensity on the solar panels. Several common maximum power point tracking algorithm is selective analyzed.MPPT control scheme, the eventual adoption,is proposed. The high speed of track and accuracy of the algorithm is proved by simulation.And it is a good solution to misjudgment. At last,the required hardware circuit to achieve system performance is built, a software program is written,the experimental prototype is debugged. The experimental results show that it operates well, which achieves the desired performance and has good economic and social significance.