Electromagnetic Interference Analysis And Filter Protection Of Shielded Cables

With the progress of semiconductor technology,electronic equipment toward the modular,high power,high integration,miniaturization.The electromagnetic compatibility of electronic equipment has become prominent.At the same time,human intentions and electronic equipment inadvertently radiation to the electromagnetic waves,making the environment is full of various complex electromagnetic fields.The impact of this environment on electronic systems can not be ignored.Especially,the strong electromagnetic pulse,which carry high power and wide band of electromagnetic waves,have serious damaging effects on electronic equipment.Cables as the carrier are used for data transmission or power transmission between the linked equipment.And most part of the cables are exposed to a complex electromagnetic environment.It is vulnerable that the cables couple strong electromagnetic pulse.The coupled electromagnetic interference get into the equipment via the cable,that is easy to damage the electronic equipment.Therefore,the analysis,prediction and prevention of the electromagnetic coupling of the shielded cables are of great significance and practical value to improve the reliability of the electronic equipment.That can guide the design of the electronic equipment.Firstly,the time domain hybrid algorithm applied to the electromagnetic coupling analysis of shielded cables is studied.(FDTD)method,transmission line equation(TL)and fast calculation method of cable excitation field,and combined with the inverse convolution technique,the efficient time domain hybrid algorithm is studied.This algorithm can be used for simulating electromagnetic coupling of shield cables.This simulation results are compared with the other literature results,and the correctness and validity of the algorithm are verified.Then,the effect of different load,different cables height and different electromagnetic wave incident angle is analyzed by using the hybrid algorithm.Secondly,the influence of the error of the transfer impedance model of the shield cable on the coupling analysis is considered.The calculation models of transfer impedance are introduced,and propose to optimize the braided angle and the shield diameter Dm parameters in the model by cable braid coverage K.According to the design of the three coaxial transfer impedance measurement device to measure the transfer impedance of the cable to verify the optimization of the cable transfer impedance model of the effectiveness of this article.Based on these work,the electromagnetic coupling of the different structure of the shielded cables are analyzed.Then,this optimized transition impedance model is combined with the time domain hybrid algorithm to improve the accuracy of the algorithm.Finally,the electromagnetic coupling of the electromagnetic pulse to the shielded cable is analyzed with a filter.The first is the establishment of an electromagnetic coupling model for shielded cables and connect the matching load at both sides of the shielded cable.Then,the above algorithm is used to simulate and obtain the voltage and current response of the inner line.And make a further analysis to obtain the amplitude response,frequency range and other information.Then design the filter according to the relevant information.With this voltage and current response as the interference source,combined with the circuit simulation software analysis of the effect of the filter.The design of filter for shielded cable is analyzed.