Use of Vector Fields to Model the Physical Blockage from Power Supply, Cable, andTransformer Sources

摘要

This effort was designed to improve electromagnetic (EM) analysis techniques thatcan be used to supplement the Intelligent EMC Analysis and Design System (IEMCADS). The primary objective of the work was to model the physical blockage of magnetic fields produced by IEMCADS sources. The sources include transformers, cables, and power supplies, all of which IEMCADS represents in a simplistic and scalar form to yield worst case field conditions. These sources do not give rise to uniform fields or plane waves, but to fields that vary as inverse powers of the radial distance. It was decided that the best way to obtain an analytical solution to the problem was to expand the IEMCADS sources in Legendre polynomials and use a hollow cylindrical physical blockage as a representation of cabinets. This technique enables the fields in the various regions around and within the physical blockage to be modeled as expansions in Legendre polynomials. These expansions make the source modeling compatible with the physical blockage modeling, and thus allow boundary conditions to be applied for the B and H fields at the two interfaces of the cylindrical shell. The application of the boundary conditions generates a system of 10 equations and 10 unknowns for the coefficients of expansion for each source type. The solution of the 10 equations and 10 unknowns yields the coefficients of expansion of the Legendre polynomials. The final Legendre polynomial expansions produce the magnetic scalar potentials for the different sources. The gradients of the magnetic scalar potentials are taken to yield the vector B and H fields in the regions of the source, the regions outside and within the shell of the physical blockage, and the hollow region of the physical blockage.