Research On Single Non-isolated Grid Research On Single-phase Two-stage Soft-switching Isolated Grid-tied PV Inverter Switching

The energy in our country is characterized by its great energy reserves, low per capita share of resources and disequilibrium of resource distribution, so the development of power industry is effective and useful to solve these problems. Solar power generation has great potential in the development of electric power because of its safety, stability, convenience and cleaning. However, single-pahse two-stage non-isolated grid-tied PV inverter is core equipment, which can turn solar energy into electricity and whose research focus on how to decrease the switching power loss of circuit. And soft-switching technology can solve this problem by reducing the switching power loss when turn on or turn off the switches. In order to put right the weakness, some improved measures were proposed in this paper. In this system, boost soft-switching converter worked as first circuit, H6 full-bridge soft-switching inverter worked as second circuit, the full text was arranged as follows:Firstly, basic principles, equivalent circuits and oscillgrams of four kinds of soft-switching working modes, which include zero current turning-on, zero voltage turning-off, zero voltage turning-on, zero current turning-off were concluded briefly. In addition, two kinds of common zero transition PWM circuits were introduced.Secondly, soft-switching technology was introduced to reduce the switching power loss of boost converter, the main switch S1 can only achieve zero current turning-on under traditional modulation strategy, but improved modulation strategy was put forward, which can make the main switch S1 achieve zero current turning-on, the conclusion proved to be right under the simulation.Thirdly, soft-switching technology was introduced to reduce the switching power loss of H6 full-bridge inverter, however, it is impossible for the auxiliary to achieve zero current turning-off, so improved topology, modulation strategy were proposed to solve this problem.Finally, single-pahse two-stage non-isolated grid-tied PV inverter was designed,whose first cicruit was boost soft-switching converter and second circuit was H6 full-bridge soft-switching inverter, the results were given, including the main circuit working principle, the overall design scheme and part of experiment results.