Noise Suppression Mechanism Modeling Method Of Complex Electronic Systems And Electromagnetic Interference

With the rapid development of automotive electronics, wireless communications and the internet of things, electromagnetic interference(EMI)noises are produced by the electronics devices via cable transmission and space coupling, which give rise to severe electromagnetic environment pollution and affect the operational functions of the other electrical equipments. According to the above problems, in the paper:(1) The uncertainty of conducted EMI noise standard measurement was evaluated based on high frequency parasitic parameters in circuit topology of artificial mains network. Common mode (CM) and differential mode(DM) conducted EMI noise models were established based on balance and non-balance noise circuits.A novel noise separation network was proposed with radio-frequency transformer and CM choke. And noise source impedance was extracted by employing dual resistances calibration and Levenberg-Marquardt’s algorithm.(2) CM and DM radiated EMI noise models and equivalent circuits were established based on electric dipole and magnetic dipole.Radiated EMI mechanism and its experimental setup were proposed through the relationship between near field wave impedance and measurement distance. And radiated EMI noise was estimated by employing voltage driven model.(3) Conducted EMI noise suppression methods were presented based on crosstalk, no well grounding and impedance mismatch, and radiated EMI noise suppression approaches were proposed according to no well grounding, large loop signal,crosstalk, transmission line and impedance mismatch.(4) The equivalent circuit of the excitation coil’s transfer impedance was introduced for magneto-rheological damper(MRD).Conducted and radiated EMI noise models were established through cable transmission and space coupling based on MRD and its semi-active control strategy. EMI noise suppression methods of MRD were proposed by employing the optimization design of shell structure and excitation circuit. Smoothing filter algorithm without delay of the semi-active control signal was designed for radiated noise reduction.The theoretical simulation and experimental results show that the characteristic parameters of the present novel network, whose DMIL decreases2dB and DMRR increases8dB,are superior to Mardiguian’s network. The amplitude frequency and phase frequency characteristics and their equivalent circuits can be obtained by using the proposed method with high precision and no constraint. The electric field and magnetic field distribution and the relationship between near field wave impedance and measurement distance can be analyzed based on radiated noise diagnosis method, which can separate CM and DM noises.The maximum radiated electric field intensity can be calculated through noise circuit in the cable, measurement distance and radiated impedance of the cable according to the present radiated noise estimation approach, especially250MHz before. The conducted and radiated EMI noises can be reduced effectively and pass GB9254for8electronics products, such as vehicle navigation, medical equipment and electric power equipment. The amplitude frequency and phase frequency characteristics of the excitation coil’s transfer impedance of MRD can be extracted based on the introduced method under the condition of static and different drive current.The EMI noises of MRD and the semi-active control strategy are suppressed efficiently by employing the optimization structure and excitation circuit of MRD and smoothing filter algorithm without delay, which can provide theoretical basis and practical guidance to scheme design of the EMI noise reduction for the complex electronics devices, such as MRD and its semi-active control strategy.