Date of Award:

12-2020

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Electrical and Computer Engineering

Committee Chair(s)

Regan Zane

Committee

Regan Zane

Committee

Abhilash Kamineni

Committee

Don Cripps

Committee

Doran Baker

Committee

David Geller

Abstract

Power distribution with DC source is advantageous over its AC counterpart in long distance distribution network due to the absence of effects of reactive components. Long distance power distribution with traditional voltage source suffers from drop in voltage over the length of the cable due to its impedance and forces the converters in the network to be over-designed with higher power rating than needed. In underwater power distribution network such as ocean observatory, marine sensors on the sea-bed etc., power conversion modules are situated at a distance far away from the shore, ranging from tens of kilometers to hundreds of kilometers. DC current distribution offers ruggedness against voltage drop over the length of the trunk cable and thus eliminates the need of converter over-design, making it the preferred choice in underwater long distance power distribution network. Moreover, distribution with DC current source improves the overall system reliability with robustness under cable fault scenarios.

Converters used in underwater system require operation with high reliability with little to no maintenance due to their geographical locations. Resonant converters offer quiet and efficient operation with low EMI due to low di/dt and dv/dt owing to sinusoidal current and/or voltage and soft-switching. This makes resonant converters an excellent choice for reliable, long term operation in underwater distribution system. However, designing resonant converters with constant current input imposes certain challenges as compared voltage source input, which are analyzed in this work. Addressing these challenges it is shown how different resonant power conversion topologies can be suitably selected and designed to meet the end goal of regulating its output current or voltage for wide range of loads. Soft switching requirements of these topologies are also investigated with appropriate solutions to ensure devices used in these converters switch with low loss and dv/dt. Some of the critical loads in the system demand bidirectional power transfer capability which is also presented in this work with befitting topology. Detailed modeling, analysis, design and experimental results from hardware prototypes are presented for all the converters in the system operating with 250 kHz switching frequency, regulating its output voltage or current from 1 A DC current source, up to a power level of 1 kW.

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