Condition Monitoring of MMC Submodule Semiconductors

Submodules are the building blocks for MMC-type HVDC converters and therefore of utmost importance for converter reliability. In order to unlock smarter maintenance strategies for submodule semiconductors, the technical condition of the semiconductors needs to be estimated to form a health index. Besides the non-project-specific traditional...

Design of Balancing Converter for Bipolar DC Grids Using Series Connected MOSFET Switches

Global electricity usage has been increasing exponentially over the last 40 years and with the current pace of population and economic growth, the same trend will continue in the coming years. However, the current electricity generation is predominantly fossil fuels based, which makes the overall process unsustainable and polluting, and is...

Evaluation of the Potential Radar Cross-Section & Experimental Aero-Acoustic Noise Merits of the GA-ASI MQ-9 Reaper by Applying Flap Morphing

Defence institutions and military aircraft manufacturers are increasingly exploring the ways to im- prove stealth in new aircraft designs. Design for low observability, more specifically for low Radar Cross-Section is the fundamental design aspect during design of a new military aerial vehicle. Acoustic stealth is also an important...

Optimising the Input Filter of Traction Installations in DC Railway Power Systems

In the world of DC railway trains nowadays, asynchronous-traction machine with traction controllers, i.e. an inverter with variable output frequency, is implemented. This controller changes the incoming DC voltage into an AC voltage of a variable frequency and RMS amplitude. The disadvantages of switching inverters, compared to a pure sine wave...

The use of RFID technology to measure dielectric coefficients of diethyl ether-oil-brine mixtures for enhanced imbibition experiments.

Characterization of fluid properties is significant in the petroleum engineering practice, especially in solvent-based enhanced oil recovery (SEOR) where the use of injected chemicals should ideally be reduced to the bare minimum in order to minimize the costs and environmental impact of SEOR. However, current techniques for measurement inside...

Design of a fully integrated CMOS highly temperature stable frequency reference

A new fully integrated frequency reference has been designed, fabricated and measured. The goal of the design procedure has been high stability of the frequency over temperature variations. This should be achieved using a CMOS technology without MEMS and crystals, while being restricted by a very low power budget. The frequency is designed based...

A Precision RC-locked Oscillator

In this thesis, the development and implementation of a new precision RC-locked oscillator topology suitable for wireless sensor networks (WSNs) is described. The objective of this thesis was to investigate the performance of the proposed topology and to compare this with the state-of-the-art in terms of accuracy and power consumption. The new...

Solution of the vector wave equation using a Krylov solver with an algebraic multigrid approximated preconditioner