Research On Transmission Line Crosstalk Method Based On Multi-conductor Transmission Line Theory

With the development of high integration of equipment brought by the continuous progress of science and technology,the electromagnetic compatibility problem in modern power electronic system is becoming more and more significant,and the phenomenon of crosstalk is also coming.Crosstalk will cause potential safety risks to the equipment and bring expensive rectification costs in the later stage.In view of these phenomena,this dissertation conducts a series of studies on the crosstalk problems existing in the multi-conductor transmission line system,and the main work is summarized as follows:Firstly,this dissertation focuses on the equation of multi-conductor transmission line and the calculation of distribution parameters.The equation of multi-conductor transmission line is derived from two different angles,namely,Maxwell equation in integral form and equivalent circuit theory of unit length.In the process of derivation,the concept of distribution parameters of unit length is introduced.The numerical method represented by the finite element method and the analytical method represented by the mirror image method are used respectively to derive the parameters of the unit length distribution theoretically,and the comparison between the two methods is given.The calculation results show that the derivation process of the mirror image analysis method needs to ensure the wide interval between transmission lines because the proximity effect is ignored.Secondly,the transient analysis of multi-conductor transmission lines in time domain is studied in this dissertation.The basic principle of Kambiz Afrooz difference scheme and ?-Leapfrog-FDTD difference scheme are expounded and theoretically deduced respectively,and the iterative general formula is given.The accuracy and effectiveness of the proposed method are proved by using ?-Leap Frog-FDTD to solve the case where nonlinear load is considered at the end of the transmission line.Aiming at the common phenomena of nonphysical oscillation at the discontinuity and too wide of the transition region in FDTD,a non-stable differential scheme called Implicit Wendroff is designed.An example shows that the method can make up for the problems of ? Leapfrog-FDTD dependent on the CFL stability condition and the low computational efficiency of Kambiz Afrooz.Finally,the steady state analysis of multi-conductor transmission lines in frequency domain is studied,and its general solution is obtained by using the method of modulus decoupling.In the analysis of terminal conditions,multi-conductor transmission lines are characterized by the properties of dual-port network,and the concept of chain parameter matrix is derived.An example is given to prove that multiconductor transmission lines can be approximated by lumped parameter circuit model under small electrical size.The chain parameter matrix method is used to approximate the non-uniform transmission lines in two different cases of sag arrangement and non-parallel arrangement,and the influence of the number of segments on the accuracy of the solution is explored.When the power and frequency of the external electromagnetic environment in which MTL is located reach a certain threshold,or there are some external factors that promote the transmission line to be acted by the external field source,the common mode current will flow in the conductor.In this case,the "field-line coupling" model can be used to characterize the MTL system.It is proved that the FDTD algorithm is a very accurate method to solve the field-line coupling model by calculating the uniform plane waves under three different incidence modes.