Research On EMC Of Non-isolated Solar Inverter Connected To Grid

With the development of the new energy,the development of photovoltaic powersystem also step into the high way.because of so many power system being conneceted to thegrid, harmonic component is brought into the grid, so the EMC in requirements must beproposed. However the non-isolated solar inverter connected between pv arry and the gridhas no Isolation Device, so the leakage current problem must be taken into consideration.meanwhile, the sysyterm is susceptible to the EMI brought by the same reference ground ofthe systerm which desgined to solve the problem of GroundBounce Noise.The non-isolated solar inverter systerm testbed with the boost and Full Briudge structurehas been built, and many experiments has been performed for further study.In this paper,And many improvements including the improvement of the clamping circuit of the SMPS,absorbing circuit and driving circuit, EMI filter, the optimal design of the PCB board andtopology have been made,through which the EMI interference is effectively restrained,besides,the EMC of the system is improved and the cureent harmonic is eliminated up to1%,Radiated Interference is decreased12db in the horizontal direction,13db in vertical direction,Conducted Interference is decreased19db.On the other hand, the software optimization is also implemented, including, medianfiltering and mean filtering as well as prediction algorithm based on the Taylors formula，reduce the possibility to restart,improve work efficiency.The application of Bipolar Pulse Modulation is proposed to restain the Common-modeCurrent on the inverter, and the inverter successfully parallel in the grid by the application ofBipolar Pulse Modulation,meet the function of reactive output by the phrase angle (±0.95)controlling.Finally, comprehensive research on the insulation resistance and residual current in PVsystem with transformer-less inverter has been made. Based on the research, both thedetecting circuit and protection circuit are designed, which are proved to be feasible andeffective through lots of experiments.