Abstract
M.Ing. (Electrical and Electronic Engineering)
The possibilities and technology of converters with an alternating
voltage link are investigated for high specific power conversion at
high frequencies. With a view to the functional description of these
power converters, s i muLat i on techniques are considered for both
system and circuit analysis. A thorough investigation is made into
the design of high frequency power transformers, which play an important
role in this class of power circuits. This includes a theoretical
analysis in conjunction with the 'practical implementation of a
design procedure for minimal eddy current losses in the windings as
well as experimental work on losses in ferrite cores. For the
remainder of the study, attention is focussed on the two pulse inverter
which is responsible for the generation of the alternating
voltage in the high frequency link. The suitability of bipolar and
field effect transistors for power switching, is critically examined
and a voltage compensation on the bipolar Darlington, which reduces
on-state losses, yielded good results upon application. A study on
the feasibility of non-dissipative snubber techniques on the centre
tapped inverter is presented, thus supplying a practical way of reducing
switching losses without affecting the efficiency of the
system. An additional, yet simple, network is added to the snubber
circuits of the two pulse inverter which is operational during low
load conditions.' in order also to have low switching losses under
these circumstances. Finally a 50 k~v, 10 kHz centre tapped inverter
was developed and built.