This paper describes a method for modelling the printed conductors
employed in high-frequency (range 10 kHz-1 MHz), medium-power (several
kW) static converters, in order to simulate their conducted interference
emissions. The principle of this method is to divide the circuit's
layout into elementary rectangles. These rectangles are then
substituted by a bundle of thin cylindrical wires. Afterwards,
it becomes possible to determine an electrical equivalent circuit
for each bundle, which integrates inductive, capacitive and resistive
effects. In the first section of this paper, the theoretical
development, with respect to a single rectangular conductor,
is presented. The printed conductor and the thin-wire bundle
equivalence conditions are then specified in the second section,
and the validity of this principle is experimentally verified.
The third section is devoted to modelling the coupling phenomena
between two printed conductors. Special attention has been paid
to separating strong and negligible couplings, in order both
to reduce the computing time and to extract equivalent circuits
for a complex layout. Quantitative coupling criteria, based
on geometrical and current quantities, are proposed; they establish
the complexity of the equivalent circuits and thereby the simulation
time. The paper's final section focuses on the experimental
aspects of this research work. A chopper has been developed
on a PCB. Experimental and theoretical results are also compared:
the impedance curves of the entire circuit and the conducted
emission spectrum of the converter are presented and discussed.
The role played by the PCB in the conducted EMI is clearly revealed
and allows the designer to optimise the printed circuit pattern.