Abstract:
Advances in power electronics over the last 30 years have enabled the re-
alisation of highly efficient energy conversion systems. Such systems have
found use in applications such as electrical networks and renewable energy
interfaces etc. A converter which has recently received much attention is
the isolated Dual Active Bridge (DAB) dc-dc converter. This converter has
the potential for bidirectional energy flow at high powers and efficiencies;
the latter being a result of its soft switching capabilities. The ability of the
converter to operate efficiently at high switching frequencies enables it to be
effectively applied in systems requiring high bandwidth control.
Recent publications have focused on the modulation strategy of the DAB
converter and its effect on the efficiency of the power electronic switches. The
Triple Phase Shift modulation method has been found to be highly effective to
reduce reactive power and minimize the current stress. The shortcomings of
these approaches are that the shape of the waveform applied to the isolation
transformer not only affects the power losses of the power electronics but also
the transformer losses and therefore the overall converter efficiency.
This thesis presents two main contributions to knowledge in this area.
The first is to consider the effect of the modulation method on the effi-
ciency of the transformer to maximise the efficiency of the overall converter
rather than just the power electronics. The second is to obtain high band-
iv
width control and fast dynamic response by augmenting the Triple Phase
Shift modulation method of the converter with a predictive control strategy.
Analysis is supported by complete experimental results from an 1kW DAB
lab demonstrator.
