Master of Science in Engineering - Engineering / In this thesis, laser-triggering of spark gaps was investigated. In other words, the purpose of the project, was to ascertain what type of laser (in terms of wavelength, energy and pulse width) is the most efficient to accomplish elec-trical breakdown across a short spark gap. The spark gap used was set up in a coaxial geometry and the gap length was able to vary from 20 mm to 2.5 mm or less. Two lasers were used: A KrF excimer (248 nm - UV) and an Nd:YAG (1064-532-355 nm). Experiments showed that a gap of 5 mm in air and a focusing lens of 100 mm, yielded the best (widest) voltage breakdown range. It was found that the key element that will ensure electrical breakdown in a spark gap, was power density (W/cm2). A power density of about 10 GW/cm2 is needed to create a spark in air. In the case of the KrF laser, the voltage range was found to be 2-13 kV (216 mJ/pulse). In the case of the YAG laser operating at 1064 nm (170 mJ/pulse), the range was 600 V-13 kV and for 532 nm (40 mJ/pulse), 3 kV-13 kV. The wavelength of the laser did effect the result. For 1064 nm, breakdown in air occured at 70 mJ, whereas at 532 nm, breakdown occured at 40 mJ. For the case where the SF6 gap was used, the range was found to be much larger than in the case of air. This can be attributed to the sensitivity of this gas to high intensity electric fields.

Thesis (MEng in Electrical Engineering)--University of South Australia, 1996

Thesis (M.S.E.E.)--University of Central Florida, 2009. / Adviser: Issa Batarseh. Includes bibliographical references (p. 79).

Thesis (M.S.)--Ohio State University, 1987. / Includes bibliographical references (leaves 224-228). Available online via OhioLINK's ETD Center

The Department of Electrical Engineering at the University of British Columbia acquired a high-voltage test set in 1979 for teaching and research purposes. To make this test set useful for experiments which undergraduate students can do themselves, various additions and modifications had to be made. This thesis describes these additions and modifications. First, a Faraday cage had to be constructed with interlocking safety circuits. Experiments were then developed to show basic high-voltage phenomena with AC voltage, with DC voltage, and with impulse voltages. Considerable modifications were required to eliminate noise in the impulse measuring system. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 125-127).

The role of high/medium power bidirectional DC-DC converters in the next generation of multi-terminal high voltage DC transmission networks is to enable intercontinental bulk power transfer. This is encouraged by increased DC-DC converter functionalities such as DC voltage stepping/matching, DC line tapping, power flow regulation, bidirectional power flow control, and DC fault isolation. In this work, a bidirectional dual active bridge (DAB) DC-DC converter is selected to pursue such functionalities, due to its desirable features for use in high power applications. This includes galvanic isolation, fast power reversal, high power density, buck/boost operation, possibility of high stepping ratio of conversion and its inherent fault isolation capability without a need for a very fast controller. However, increased reactive power and reduced soft switching range are the main limitations of DAB for applications involving high voltage conversion ratios. Reactive power circulation increases the converter RMS current leading to an increase in conduction losses especially in high power applications. Therefore, a novel triple phase shift (TPS) control algorithm that minimises the total reactive power is proposed to enhance the performance of the DC-DC converter. The algorithm iteratively searches for TPS control variables that satisfy the desired active power flow while selecting the operating mode(s) with minimum reactive power consumption. In addition, a complete DAB converter behaviour under TPS control which has not been studied in the literature before is performed for both power flow directions. Steady state analysis is undertaken for each mode by computing exact expressions for modes power transfer and range (to characterise mode boundary) without fundamental frequency assumption. A new definition of reactive power consumption based on converter total inductance is proposed and a detailed constraint for zero voltage switching (ZVS) is also presented. Moreover, it is shown that all known DAB phase shift modulation techniques including conventional, dual and extended phase shift, represent special cases of TPS, therefore the presented analysis provides a generalised theory for all phase shift based modulation techniques. To scale the converter to higher power level, a modular DAB converter is implemented with a development of power sharing controllers that utilise TPS modulation scheme. The focus is to ensure stable operation of the DAB modules in both power flow directions in the presence parametric mismatches. The reactive power minimisation algorithm and a new DC fault management mechanism are embedded within the proposed controllers. Detailed simulation and experimentation are used to validate the proposed algorithm and power sharing controllers.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 131-133).