Study On Electromagnetic Interference Of Transmission Line Based On FDTD Algorithm

As today’s society has entered the electronic information age,electrical and electronic equipment is playing an increasingly important role in the development of every industries.At the same time when these equipments are running,it is inevitable that some electromagnetic energy will be coupled to other equipments or other parts of itself through space or dielectric,which will cause interference or even damage to the equipment.The electromagnetic interference between transmission lines is one of the problems that need to be studied.The multi-conductor transmission line theory is the basis of the study of transmission line problems.The finite-difference time-domain algorithm(FDTD)is a commonly used numerical method to solve the telegraph equation of multiconductor transmission line,but the traditional FDTD algorithm is limited by the Courant-Friedrichs-Lewy condition and numerical dispersion characteristics,so it has many limitations in use.In order to break through the above limitations,the high-order finite-difference time-domain algorithm(FDTD(2,4))and the local one-dimensional finite-difference time-domain algorithm(LOD-FDTD)are used to solve the multiconductor transmission line telegraph equation,and then the electromagnetic interference characteristics between transmission lines are studied.The main research contents of this thesis are as follows:1.The discrete iterative equations based on the FDTD(2,4)algorithm and the high-order LOD-FDTD algorithm are derived respectively for the uniform multi-conductor transmission line model.The specific models are established and their electromagnetic interference characteristics are simulated.At the same time,the numerical dispersion characteristics of FDTD(2,4)algorithm,the unconditional stability characteristics of LODFDTD algorithm and the efficiency of these two algorithms are verified.In view of the poor numerical dispersion characteristics of the LOD-FDTD algorithm,this thesis also improves the LOD-FDTD algorithm by using a high-order precision differential method.It is proved that the high-order LOD-FDTD algorithm is a cost-effective solution method which takes into account the computational efficiency and accuracy.2.Based on FDTD(2,4)algorithm,the electromagnetic interference of non-uniformly lossy multi-conductor transmission lines is studied in this thesis.The influences of non-uniformity,non-parallelism,non-frequency dependent loss and frequency dependent loss on electromagnetic interference between transmission lines are investigated respectively.At the same time,a non-uniform transmission line model with coupled microstrip line structure is established,and the influence of dielectric substrate thickness and permittivity on the electromagnetic interference between lines is explored.3.Based on high order LOD-FDTD algorithm,the electromagnetic interference problem of overhead multi-conductor transmission lines on the ground is studied.The influence of long-distance transmission line deformation caused by falling,the non-ideal of the earth and the height of transmission lines above the ground on the electromagnetic interference between overhead transmission lines is explored.