The Research Of Vector Fitting Algorithm In The EMC Analysis Of The Transmission Line

The core of EMC analysis in electronic and power system is modeling disturbance source, coupling path and sensitive equipment. The application of Vector Fitting in the EMC analysis of the transmission line (including the transmission line of PCB) is discussed, and the model of transmission line is deduced. Vector Fitting is improved when noise exists.In this paper, based on the deducing of the telegram equation and the uncoupling equation instead of the coupling equation by modal decomposition, the propagation function and the characteristic admittance are fitted by Vector Fitting. The macro model is achieved in phase domain. Taking the 5 conducts transmission line as an example, the fitting result of the propagation function is comparatively ideal, and we can get the RMS error of 2.0982e^-005 by 4 iterations.The fitting result of Vector Fitting is not ideal when noise exists, and there is a need to improve Vector Fitting. The band limit norm _μn(p) of spurious poles does not affect the fittingprocess too much, so the spurious poles can be deleted. The maximums of frequency-dependent error△_ij (ω) between model and data can be selected to be the addingpoles. The Vector Fitting is improved by deleting spurious poles, adding starting poles and the number of adding process. The number of iterations is reduced to 3 from 8, and the RMS error also achieves 9.5684e⁰⁰⁶.Vector Fitting can also be used in the transmission line in PCB, and the RLC equivalent circuit model is discussed based on poles and residues in the transfer function with real poles and complex poles.The macro model of transmission line based on Vector Fitting and the equivalent circuit model of the transmission line in PCB can be used in EMC analysis.