Research On EMI Mechanism Based On Boost PFC Radiation

Reduce the harmonic pollution of power electronics to the power grid through the Power Factor Correction(PFC)function in the switching power supply.However,due to the increased operating frequency of the switching power supply,external cables and internal switching devices generate strong electromagnetic interference(EMI)noise,which affects the normal operation of the internal electronic equipment.Faced with the above problems,this paper establishes the EMI model radiated by Boost PFC circuit,the EMI model of cable radiation and the shielding model of the casing.Through the construction of the above model,the generation mechanism of radiation noise and casing shielding is further revealed.After that,an effective suppression method is proposed,as follows:First,modeling common mode radiation and differential mode radiation,based on the EMI noise generation mechanism of circuit radiation.Using the common mode and differential mode radiated noise formula,the high frequency noise current extracted from the circuit simulation software is calculated,and then the EMI noise caused by different inductance values ??is analyzed.Secondly,for different antenna models,the EMI noise prediction method for cable radiation is based on the extraction method and application range of the cable radiation impedance.The CST simulation software was used to build a cable model with inconsistent length for comparative analysis,and the improved prediction model and Todd Hubing voltage prediction model were also compared.Then,for the different apertures of the opening of the casing of the switching power supply PFC,the shielding effectiveness is analyzed,and the shielding mechanism of the good metal conductor is analyzed.Simulation analysis and comparison of shielding effectiveness were performed using CST simulation software.Through experiments,the shielding effectiveness of the casing and the effectiveness of the simulation model are verified.Finally,the hardware circuit of Boost PFC was designed based on the control chip of Texas Instruments(TI).Three suppression experiments were performed on the hardware circuit,namely cable radiation,circuit radiation and chassis shielding,thus verifying the correct validity of the study.