屏蔽电缆参数计算及屏蔽层与芯线间的串扰

为分析线缆间的串扰问题,基于有限元软件ANSYS分析了屏蔽电缆周围的电磁场分布,通过计算导体所带电荷量以及磁链,求得了多导体传输线系统的电感电容矩阵。针对位于地面上方的屏蔽电缆系统提出了一种新的表示其传输线参数的模型,即以大地为参考导体,建立包括芯线、屏蔽层、大地的统一模型,计算其相应的传输线参数;运用所得屏蔽电缆的传输线参数,结合传输线时域有限差分(FDTD)法,仿真分析了屏蔽电缆屏蔽层中的电压、电流在电缆芯线中的耦合响应问题;基于实验室研究设备,对同轴电缆屏蔽层与芯线之间的耦合问题进行了实验测量,验证了理论研究的正确性。

Parameters Calculation of Shield Cable and Crosstalk Between Shielding Layer and Core Wires

Based on the finite element software ANSYS,the electromagnetic field around the shield cable were analyzed,the inductance and capacitance matrices of the multiconductor transmission lines were acquired by calculating the quantity of electric charge and flux linkage of the conductor.Through the contrast it is shown that the precision of this method is very high,and it can be used for complex and irregular section transmission line model.A new model was advanced for the expression of transmission-line parameters of the cable with shielding above the ground,it takes the shielding of the cable as one of the transmission lines with ground as the referent to calculate its transmission-line parameters.With the obtained parameters,the crosstalk between shielding layer and core wires were analyzed by the Finite difference time domain method (FDTD).The problems were experimentally studied,and comparison of the data of the experiments with simulations shows that both waveforms and amplitudes are basically identical,thus the methods presented in this paper are demonstrated to be effective.