The development of a DC-DC converter for use in a proposed range of one to ten
kilowatt off-line power supplies is presented. The converter makes good use of
established design practices and recent technical advances.
The thesis begins with a review of traditional design practices, which are used in the
design of a 3kW, 48V output DC-DC converter, as a bench-mark for evaluation of
recent technical advances. Advances evaluated include new converter circuits, control
techniques, components, and magnetic component designs. Converter circuits using
zero voltage switching (ZVS) transitions offer significant advantages for this
application. Of the published converters which have ZVS transitions the phase shift
controlled full bridge converter is the most suitable, and assessments of variations on
this circuit are presented. During the course of the research it was realised that the
ZVS range of one leg of the phase shift controlled full bridge converter could be
extended by altering the switching pattern, and this new switching pattern is proposed.
A detailed analysis of phase shift controlled full bridge converter operation uncovers
a number of operational findings which give a better and more complete understanding
of converter operation than hitherto published. Converter design equations and
guidelines are presented and the effects of the new improvement are investigated by
an approximate analysis. Computer simulations using PSPICE2 are carried out to
predict converter performance.
A prototype converter design, construction details and test results are given. The
results obtained compare well to the predicted performance and confirm the
advantages of the new switching pattern.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.