Research And Design Of The Passive EMI Filter At The Input Terminal Of A Medium-power Or High-power Inverter System

The medium-power or high-power inverter shave the advantage of large torque, large power, convenient adjustment of positive & negative acceleration & deceleration, soft start-up, power factor compensation, energy feedback, energy saving. So they play a more and more important role in the industrial fields of electric drive system. But they produce much transmitting or radiant electromagnetic interference with high amplitude in broadband range. It can pollute the electromagnetic environment in power grid, and influence the normal operation of the electrical and electronic equipment near the inverters. For this reason, the research related to electromagnetic compatibility of the inverter has become one of the most important steps in the development and application of medium-power or high-power inverter systems. For the serious electromagnetic conducted interference polluting the power grid, produced by the input terminal of medium-power or high-power inverter system, this paper makes a analysis of the theoretical basis for the design of passive filter in details, based on the exposition of the characteristics of electromagnetic noise and the electromagnetic compatibility requirements, such as, two-port network, impedance mismatch, model equivalent circuit, high frequency model, grounding system, etc. Then, from the angle of design practice about the EMI filter, this paper expounds the selection basis of the type and parameters of different components, the method for topology determining, the reference standard of the actual layout. And design an EMI passive filter which can attenuate the system noise very well.Finally, combined with a large number of experiments, measurement experience in related subjects, this paper introduces the experimental methods such as equipment testing, installation, layout about EMI passive filter when the electromagnetic compatibility testing is done, and measure the EMI noise. By the EMI noise suppression using EMI passive filter, the inverter system can meet the national related standards. At the same time, a series of improvement measures and matters needing attention, etc. are summarized.