In the drive towards power electronic integration, planar structures are widely used.
Applications for the use of these structures are varied. These have been shown to have
potential advantages with regard to reduction in size and cost. Much work has been done with
regard to integration, but generally from an intuitive perspective, and without a general
approach.
An important part of power electronic integration is EMI filtering. One way in which this is
achieved is through dissipative filtering. It is demonstrated that this can be done for planar
structures through the use of multi-layered conductors. Planar conductors have a particularly
distinct advantage in that they are low profile and can be miniaturised. The resulting focus of
this dissertation is an investigation into the characterisation of two-layer conductors in terms
of how the properties of the two layers contribute to the frequency dependent resistance of
the conductor. This is done with a direct view towards dissipative filtering.
This investigation begins with a description of the method of characterisation of two-layered
conductors, and the construction of a parametric study around this. A contribution of this
dissertation is the demonstration that the parametric space can be reduced without loss of
generality of the characterisation. The results of this characterisation are used to demonstrate
the importance of the total conductivity and total permeability as concepts. This concept
provides flexibility in the design of two-layer dissipative filters.
The concept of a single-layer approximation is presented and investigated. It is shown to even
further simplify the model used for multi-layered conductors, and presents a good first level
understanding of what the frequency dependent resistance of the structure will be. This
concept is shown to be useful in the design of two-layered conductors, and may be
generalisable to multiple layers. A second contribution of this work is the presentation of
design equations based upon this approximation for five different scenarios. This contribution
includes the limits to the dimensions of the two-layer structure, with the conclusion that some
specifications do not have physically realisable forms.
The final, major contribution that this work presents is as follows. In terms of dissipative
filtering, it is shown under differential-mode excitation that the desired properties of the inner
layer of the conductor should be: less conductive than the outer layer, and more permeable
than the outer layer. These conditions are shown to provide a steeper gradient of resistance
increase with respect to frequency. This conclusion is verified experimentally, which
provides confidence in the modelling technique this dissertation is based upon.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/13737 |
| Date | 12 February 2014 |
| Creators | Leeburn, Dominic Andrew |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
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