Effect of dielectric thickness on the bandwidth of planar transformers
Date
2017
Authors
Vallabhapurapu, Hyma Harish
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Abstract
This research has considered an idealistic non-interleaved planar transformer
wherein only the electromagnetic parasitic capacitive and inductive elements arising
out of the transformer geometry are taken into account, without considering
material limitations. A suitable model for the planar transformer is used to analyse
its frequency and power transfer characteristics; this model was validated by three
dimensional electromagnetic simulations of various planar transformer structures
in FEKO simulation software. The capacitive and inductive parasitics in this model
have been found to be functions of the dielectric thickness.
The theoretical bandwidth for the planar transformer is defined in this research
as a function of dielectric thickness. The effect of dielectric thickness of the transformer
windings on the bandwidth of the transformer is analysed, based on the
premise that the inherent parasitic capacitive and inductive elements would affect
the transfer characteristics of the transformer. Upon conclusion of this analysis, it
is found that the dielectric thickness of a planar transformer can be optimised such
as to present an optimised bandwidth. A closed form analytic expression for the
optimum dielectric thickness value is derived and presented in this research.
In a design example of a 4:1 50W transformer presented in this research, it has
been shown that the bandwidth can be improved by 384%, along with a power
density improvement of 45%, upon choosing of an optimum dielectric thickness of
0.156mm to replace a standard 0.4mm thick dielectric.
It should be noted that the results derived in this research are purely theoretical,
justified by many idealisations and assumptions that are argued throughout
the research. It is thus expected that practical results should at best approach the
theoretical results, due to the known non-ideal nature of reality.
Description
A dissertation submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Johannesburg, in fulfilment of
the requirements for the degree of Master of Science in Engineering, 2017
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Citation
Vallabhapurapu, Hyma Harish (2017) Effect of dielectric thickness on the bandwidth of planar transformers, University of the Witwatersrand, <https://hdl.handle.net/10539/25527>