Study On Conducted Emi Prediction Model Of A Grid Connected Three-phase Inverter

With the wide spread of distributed generator, grid connected three-phase inverter has been used more and more frequently. However, much disturbance possibly flows into the grid, and destroys the electromagnetic environment of the grid. As a result, the other equipments are influenced. This paper has proposed a conducted electromagnetic interference prediction model of grid connected three-phase inverter, whose parameters are adjustable and structure is easier, for electromagnetic interference design and pre diction of grid conducted power generation system.First of all, the math model of conduct electromagnetic interference source has been gained through the analysis of the main switch of the inverter MOSFET and its equivalent circuit. And the parameters in the model are only related a few circuit parameters and variables besides part of parameters of switch itself. Then the time domain waveform of electromagnetic interference source has been gained by simulation. The electromagnetic interference source model has been proved to be accurate by compare the result of simulation and test.Next, the transmission channel of one phase has been obtained by analyzing the work process of one phase and comparing the process with buck circuit. Same work has been did to the other two phase. The high frequency model of elements in three-phase inverter has been got. Three-phase transmission channel and the high frequency model of elements in the inverter have been combined to make three-phase conducted electromagnetic interference transmission channel simulation model of the inverter.Finally, the electromagnetic interference source model and the transmission channel have been combined to obtain the whole conducted electromagnetic interference model of three-phase inverter. The simulated time domain waveform of the conducted electromagnetic interference model has been obtained and the simulated frequency domain waveform has been obtained by Fast Fourier Transform. The real three-phase inverter has been jointed and the parameters of the actual inverter have been obtained. The actual time domain waveform and the frequency domain spectrum of conducted electromagnetic interference in three-phase inverter have been got by test. The conducted electromagnetic interference model of grid connected three-phase inverter proved to be accurate by compare the result of simulation and test.The modeling method can not only reach the goal of easy to understand and accurate as traditional ways are, but also meet the new requirements that the model is easier and it has good randomness. So the model is more suitable for the conducted EMI prediction model of grid connected three-phase inverter.