Computer Simulation of Responses of Earth-return Circuits to the AC and DC External Excitation

摘要

The use of the circuit simulation package SPICE (Simulation Program with Integrated Circuit Emphasis) permits the complex analysis of the EMI (electromagnetic interference) on earth-return circuits. In the approach presented, the earth-return circuit with excitation by AC signals and transients, as well as with DC energization is modelled as a large multinode electrical equivalent circuit. The circuit is a chain of basic circuits, which are equivalents of homogenous sections of the earth-return circuit with uniform exposure to the primary interfering electric field associated with the inductive and the conductive influence. The application of controlled voltage and current sources in the basic circuits permit the modelling of coupling effects in systems of earth-return circuits. Contrary to the analytical methods the SPICE simulation enables one to solve the EMI problems in practical cases connected with: topological complexity of the system considered, non-homogeneous geometrical and electrical parameters of the earth-return circuits, non-homogeneous earth, application of insulating flanges, bonds, earth electrodes in a system of earth-return circuits, non-linearity of the system, etc. The SPICE simulation is an alternative and a useful approach to the analysis of EMI problems in earth-return circuits, when comparing with existing analytical and numerical solutions. The usefulness of the SPICE simulation has been illustrated by examples.