Thesis (MEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / This thesis relates to the successful development of an unmanned terrestrial vehicle (UTV) capable of operating in an obstacle ridden environment. The primary focus of the project is on the specific path planning algorithms. It is shown that specific methods of populating the obstacle-free space can be combined with methods of extracting the shortest path from these popula- tions. Through use of such combinations the successful generation of optimal collision-free paths is demonstrated. Previously developed modular architectures are combined and modified to create a UTV platform which meets all the requirements for implementation of navigational systems and path planning algorithms on board the platform. A two-dimensional kinematic state estimator is developed. This estimator makes use of extended Kalman Filter theory to optimally combine measurements from low cost sensors to yield the vehicle’s state vector. Lateral guidance controllers are developed to utilize this estimated state vector in a feedback control configuration. The entire system is then successfully demonstrated within a simulation environment. Finally, practical results from two days of test runs are provided in both written and interactive form

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis is a description of how the first magnetically geared axial flux permanent magnet generator (MGAFG) is designed, constructed and experimentally evaluated. Magnetic gears (MGs) allow for contact-less power transfer and lubricant free operation, which may solve the reliability concerns with current mechanically geared wind energy converters. However, the complex structure of MGs may present serious challenges to its design. Thus, special care should be given to the mechanical layout and the electromagnetic influence of every component. The MGAFG can be configured to be magnetically coupled or decoupled. In the coupled configuration the permanent magnets (PMs) of the MG contribute to the total flux linkage in the PM generator (PMG). The coupled configuration is therefore more efficient. The processing time required to optimise the decoupled configuration is however much faster, since the MG and the PMG can be optimised separately. The optimised results show that a torque density in excess of 100kNm/m3 could be achieved, which is significantly higher than any of known electrical machines. However, owing to excessive losses in the mechanical support structures, the prototype exhibited lower torque density and poor efficiency. The design related aspects and issues are analysed and discussed in detail in an attempt to outline problem areas in the design process. Relevant recommendations are also given for future design improvements. The costs of magnetic material accounts for over fifty percent of the total cost of the prototype. Therefore to make the manufacturing of the MGAFG more economically viable magnetic material should be minimised in the design process. / AFRIKAANSE OPSOMMING: In hierdie tesis word die eerste magnetiese geratte aksiale vloed permanente magneet generator (MGAVG) ontwerp, vervaardig en eksperimenteel geëvalueer. In magnetiese ratte (MR) is daar geen kontak tussen werkende dele nie, daarom word geen smeermiddels benodig nie. Dit dra by tot die betroubaarheid van die ratkaste in wind energie generators en kan onderhoud grotendeels uitskakel. Die komplekse struktuur van magnetiese ratte kan egter die betroubaarheid van die ontwerp juis verswak. Daarom moet die meganiese uitleg noukeurig beplan word sodat dit nie die elektromagnetiese werking ondermyn nie. Die magnetiese rat (MR) en die permanente magneet generator (PMG) van die masjien kan magneties of sonder magnetiese koppeling verbind word. In die gekoppelde konfigurasie dra all die permanente magnete van die MR gesamentlik by tot die totale vloed-koppeling in die PMG. Wat die magnetiese gekoppelde konfigurasie meer doeltrefend maak. Minder tyd word benodig om die nie magnetiese gekoppelde konfigurasie te optimaliseer omdat die MR en die PMG apart geoptimaliseer kan word. Die optimale resultate toon dat ’n wringkrag van meer as 100kNm/3 bereik kan word, wat aansienlik beter is as die van bekende elektriese masjiene. Maar as gevolg van oormatige verliese in die meganiese strukture, toon die prototipe lae wringkrag digtheid en swak doeltreffendheid. Die ontwerp probleme word ontleed en bespreek in ’n poging om probleem areas in die ontwerp te identifiseer. Relevante aanbevelings word gegee vir toekomstige ontwerp verbeterings. Die koste van die magnetiese material verteenwoordig meer as vyftig persent van die vervaardigings koste van die prototipe. Koste kan bespaar word op die vervaardiging van die MGAVG deur die hoeveelheid magnete wat gebruik word te beperk.

Thesis (MScEng)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: Wind energy is a very current topic, both locally and internationally. It is one of the most rapidly growing renewable energy sources with installed capacity doubling every three years. South Africa's installed wind energy currently accounts for only 10 MW of the 197 GW worldwide installed capacity. With a 10 TWh renewable energy production target set for 2013 by the South African government, renewable energy projects have gained momentum in recent years. This target, together with data from case studies and reports on resource planning and technical requirements, shows that South Africa is well positioned for the implementation of wind energy sources. All this development in the local wind generation market creates a need for local knowledge in the field of wind energy as well as a need to efficiently model and analyse wind turbine systems and grid interactions for local operating conditions. Although the relevant model topologies are well established, obtaining or deriving appropriate parameter values from first principles remains problematic. Some parameters are also dependent on operating conditions and are best determined from site measurements using parameter estimation methodologies. One of the objectives of this project is to investigate whether the system parameter values can be obtained by performing parameter estimation on the model of a wind turbine system. The models used for parameter estimation processes require fast simulation times. Therefore, basic C-code S-function models of the wind turbine system components, i.e., the wind turbine blade, gearbox and generator, were developed and compiled as a Simulink library. These library components were then used for the parameter estimation process. The developed models, as well as the complete wind turbine system model, were validated and their performance evaluated, by comparing them to existing Simulink block models. These models all proved to be accurate and all showed reductions in simulation times. The principle of performing parameter estimation on C-code S-function models is proven by case studies performed on the individual models and the complete wind turbine system. The power coefficient matrix parameter values of the individual turbine blade model estimated with 100% accuracy for the excited elements. The individual gearbox parameter values all estimated accurately with errors below 2.5%. The parameter values of the individual generator models were estimated accurately for the ABC model, with errors below 4%, and less accurately for the DQ model with errors below 13%. The estimation results obtained for the complete wind turbine system model showed that the parameter values of the gearbox model and generator model were estimated accurately when the system model was excited through a step in angular velocity and steps in amplitude of the stator voltages respectively. A final estimation showed that a combination of gearbox and generator parameter values were accurately estimated when the model was excited through both a step in angular velocity and steps in the amplitude of the stator voltages. / AFRIKAANSE OPSOMMING: Windenergie is 'n baie aktuele onderwerp beide plaaslik en internasionaal. Windenergie is een van die vinnigste groeiende hernubare energie bronne met die geïnstalleerde kapasiteit wat driejaarliks verdubbel. Suid-Afrika se geïnstalleerde windenergie maak tans slegs 10 MW uit van die wêreldwye geïnstalleerde kapasiteit van 197 GW. Die Suid-Afrikaanse regering het ’n 10 TWh hernubare-energie produksie teiken gestel vir 2013. As gevolg hiervan het hernubare-energie projekte die laaste paar jaar momentum gekry. Hierdie teiken, tesame met die data van gevallestudies en verslae oor hulpbronbeplanning en tegniese vereistes, toon dat Suid-Afrika goed geposisioneer is vir die implementering van windenergiebronne. Hierdie ontwikkelinge in die plaaslike windenergie mark skep ’n behoefte aan plaaslike kennis op die gebied van windenergie, asook die behoefte vir ’n doeltreffende wyse vir die modellering en analisering van windturbine stelsels en netwerk integrasie vir plaaslike werkskondisies. Alhoewel die betrokke model topologieë reeds goed gevestig is, is die verkryging van toepaslike parameter waardes vanuit eerste beginsels steeds problematies. Sommige parameters is ook afhanklik van die werkskondisies en kan die beste bepaal word deur gebruik te maak van parameter estimasie metodologieë vanaf terrein metings. Een van die doelwitte van die projek is om ondersoek in te stel na die moontlikheid om die stelsel parameter waardes te verkry deur parameter estimasie toe te pas op ’n windturbine stelsel. Die modelle wat gebruik word vir die parameter estimasie prosesse benodig vinnige simulasie tye. Daarom is basiese C-kode S-funksie modelle vir die komponente van windturbine stelsels, d.w.s., die wind turbine lemme, ratkas en generator, ontwikkel en saamgestel as ’n Simulink biblioteek. Die komponente in hierdie biblioteek was toe gebruik vir die parameter estimasie proses. Die ontwikkelde modelle sowel as die hele windturbine stelsel model was gevalideer en hul werksverrigting geëvalueer, deur dit te vergelyk met bestaande Simulink blok modelle. Hierdie modelle het almal getoon dat hulle akkuraat is en het almal ’n vermindering in simulasie tyd getoon. Die beginsel van parameter estimasie wat uitgevoer word op C-kode S-funksie modelle, is bewys deur gevallestudies wat op die individuele modelle en die hele windturbine stelsel model uitgevoer was. Die geperturbeerde elemente van die kragkoëffisiënt-matriks arameter van die individuele turbine lemme model se waardes het 100% akkuraatheid geëstimeer. Die individuele ratkas model se parameter waardes was almal akkuraat geëstimeer, met foute kleiner as 2.5%. Die individuele generator modelle se parameter waardes was akkuraat geëstimeer vir die ABC model, met foute kleiner as 4%, en minder akkuraat vir die DQ model, met foute kleiner as 13%. Die resultate wat verkry is van die estimasie wat uitgevoer is op die volledige windturbine stelsel model, het getoon dat die parameter waardes van die ratkas model en die generator model akkuraat geëstimeer word, wanneer die stelsel model onderskeidelik deur ’n trap in die hoeksnelheid en trappe in die amplitude van die stator spannings geperturbeer word. ’n Finale estimasie het getoon dat ’n kombinasie van ratkas en generator parameter waardes akkuraat geëstimeer kan word as die model deur beide die trap in hoeksnelheid en die trappe in die amplitude van die stator spannings geperturbeer word.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The use of high voltage direct current (HVDC) applications has gained enormous popularity for long distance power transmission. This is due to the lucrative benefits offered by this type of power transmission technology when compared to the traditional high voltage alternative current (HVAC). This new shift in the paradigm of power system design has led to the increased interest in the research that focuses on issues relating to the reliability of power supply associated with HVDC. Amongst such issues, insulation coordination has increasingly become a challenging task that continues to receive renewed research focus. It has been convincingly demonstrated, both from field experience and laboratory research, that insulator contamination constitutes a multifaceted phenomenon, especially when transmission voltages ramp up into high operating voltage levels. More so, this is particularly interesting with reference to the increasing applications of high voltage direct current (HVDC). The recently commissioned HVDC power-line in Namibia is one of the major motivations upon which NamPower (Namibia‟s national power utility) has committed financial resources to research on insulator pollution performance. This project was a part of NamPower‟s research initiative – seeking to investigate the phenomena associated with insulator pollution performance under natural pollution environments when energized under both AC and DC excitation voltage types. The significance of this research is especially crucial for HVDC applications given the paucity of research conducted on the DC performance of insulators, under natural pollution environments. This study was conducted at the Koeberg Insulator Pollution Test Station (KIPTS) on the west coast of Cape Town in the Western Cape province of South Africa. KIPTS is an internationally recognized insulator pollution test facility, which is widely used by both insulator manufacturers and academic researchers from many parts of the world. STRI and ABB, both Swedish-based companies, are good examples of international subscribers to the KIPTS research facility. The first objective of this research was to design a suitable DC excitation voltage system for both DC+ and DC- to be used at KIPTS. This apparatus was designed and built at the University of Stellenbosch. The second objective was to conduct a comparative evaluation of the performance of high temperature vulcanized silicone rubber (HTV-SR) power line insulators under AC, DC+ and DC- when subjected to natural pollution conditions at KIPTS. All test insulators were made from the same material and sourced from the same manufacturer – having different creepage lengths. Five different creepage lengths were considered for each excitation voltage – summing up to fifteen HTV-SR test samples. A standard DC glass disc insulator was also installed on each excitation voltage as a control sample. It was therefore envisaged that this study would give rise to new research questions, leading to future explorations on the subject. With reference to weather monitoring and leakage current measurements (using an online leakage current monitoring device - OLCA), a correlation was found to exist between the variations in climatic conditions and the corresponding occurrence of leakage current on the insulator surfaces. High leakage current levels were recorded in summer due to the high pollution levels that were measured in that season (using the equivalent salt deposit density (ESDD) approach). Winter, in contrast, had lower levels of leakage current recorded. This corresponds to a high prevalence of rainfall in winter, which caused occasional natural washing of the insulator surfaces. The leakage current levels for the HTV-SR insulators were of a similar order of magnitude for AC and DC+ and lower for DC-. The harshest pollutants (with high conductivities, as measured with the directional dust deposit gauges (DDDG)) were found to have emanated largely from the south. As a result, most instances of erosion were observed in the southward direction on the test insulators. The electrical discharge activity observations, conducted at night, had revealed that dryband corona (DBC) and dryband discharge (DBD) prominently occurred on the terminating sheaths (both live and ground ends) and bottom side of HTV-SR and glass disc insulators, respectively. This justifies the dominance of erosion that was observed on the terminating sheaths and bottom side of HTV-SR and glass disc insulators, respectively. Flashover events were recorded on the shortest HTV-SR insulator installed on DC+ and the glass disc insulator installed on DC-. All flashover events occurred in summer (the harshest season at KIPTS). Two interesting observations, albeit unexplained, were observed: star-shaped erosion on the shed bottoms of the HTV-SR insulators installed on DC+ and material peel-off at the shed-to-sheath bonding interface of the HTV-SR insulators installed on DC-. These observations therefore require further investigation in order to establish possible explanations. / AFRIKAANSE OPSOMMING: Die gebruik van hoë gelykspanning (HSGS) het baie gewild geword vir kragtransmissie oor lang afstande. Dit is as gevolg van die uitstekende voordele wat hierdie tipe tegnologie teenoor die tradisionele hoë wisselspanning (HSWS) bied. Hierdie paradigmaskuif in die ontwerp van kragstelsels het tot verhoogde belangstelling in navorsing gelei wat betrekking het op aspekte wat verband hou met die betroubaarheid van kragvoorsiening deur HSGS. Van hierdie aspekte word isolasiekoördinasie toenemend ʼn uitdagende taak en navorsing word tans daarop toegespits. Daar bestaan oortuigende bewyse, gebaseer op laboratorium- en veldtoetse dat isolatorbesoedeling ʼn verskynsel met vele fasette is, veral wanneer hoër spannings gebruik word. Dit is in „n meerdere mate van belang met verwysing na toepassings van HSGS. Die onlangs inbedryfgestelde HSGS kraglyn in Namibië is een van die hoofmotiverings vir die verskaffing van geldelike steun deur NamPower (Namibië se nasionale kragvoorsiener) vir navorsing oor die besoedelingsprestasie van isolators. Hierdie projek is deel van NamPower se navorsingsinisiatief om verskynsels betreffende die besoedelingsprestasie van isolators in natuurlik-besoedelde omgewings te ondersoek, onder WS en GS-bekragtiging. Die betekenis van hierdie navorsing is veral belangrik vir die HSGS-toepassings in die lig van die skaarsheid van navorsing oor die GS-prestasie van isolators in natuurlik-besoedelde omgewings. Hierdie studie is gedoen by die Koeberg isolatorbesoedelingstoetsstasie (KIPTS) aan die weskus van die Wes-Kaap. KIPTS is 'n internasionaal-erkende toetsfasiliteit en word algemeen gebruik deur beide isolatorvervaardigers en akademiese navorsers uit baie dele van die wêreld. STRI en ABB, albei Sweeds-gebaseerde maatskappye, is die goeie voorbeelde van die internasionale gebruikers van die KIPTS navorsingsfasiliteit. Die oogmerk van hierdie navorsing was om eerstens 'n geskikte GS-kragbron vir beide die GS+ en die GS- vir gebruik by KIPTS te ontwerp. Hierdie apparaat is ontwerp en gebou deur die Universiteit van Stellenbosch. Tweedens is 'n vergelykende evaluering van die prestasie hoë temperatuur gevulkaniseerde silikoon (HTV-SR) kraglynisolators onder WS, GS+ en GS– onder natuurlike besoedeling by die KIPTS uitgevoer. Alle toetsisolators is van dieselfde materiaal gemaak en is afkomstig van dieselfde vervaardiger, maar het verskillende kruipafstande. Vyf verskillende kruipafstande is gebruik vir elke tipe spanning  'n totaal van vyftien HTV-SR toets monsters. 'n Standaard GS glasisolatorskyf is ook vir elke spanning as' n kontrolemonster geïnstalleer. Dit kan dus verwag word dat hierdie studie aanleiding sal gee tot nuwe navorsingsvrae, wat kan lei tot verdere toekomstige ondersoeke oor die onderwerp. Met verwysing na die monitering van die weer en die lekstroommetings (met behulp van 'n aanlyn-lekstroommoniteringstoestel - OLCA), is 'n korrelasie gevind tussen die variasie in klimaatstoestande en die ooreenstemmende voorkoms van lekstroom op die isolator- oppervlaktes. Hoë lekstroomvlakke is waargeneem in die somer, as gevolg van die hoë besoedelingsvlakke wat in daardie seisoen gemeet is (met behulp van die ekwivalente soutneerslag-digtheid (ESDD) metode). In die winter, in teenstelling, is die laagste vlakke van lekstroom aangeteken. Dit stem ooreen met 'n hoë voorkoms van reënval in die winter, wat die isolatoroppervlaktes van tyd tot tyd natuurlik gewas het. Die lekstroomvlakke op die HTV-SR isolators was van soortgelyke ordegrootte vir WS en GS+ maar laer vir GS-. Dit is bevind dat die ergste besoedelingstowwe, met 'n hoë geleiding, soos gemeet met die rigtingsensitiewe stofneerslagsmeters (DDDG), hoofsaaklik uit ʼn suidelike rigting kom. As gevolg hiervan, is die meeste gevalle van erosie aan die suidekant van die toetsisolators waargeneem. Die waarneming van elektriese ontladingsaktiwiteit in die nag, het aan die lig gebring dat droëbandkorona (DBC) en droëbandontladings (DBD) prominent voorgekom het op die skedes aan die uiteindes (beide lewende en grond kante) en onderste kant van HTV-SR en glasskywe, onderskeidelik. Oorvonkings is waargeneem op die kortste HTV-SR isolator op GS+ en op die glasisolator op GS-. Al die oorvonkings het in die somer (die ergste seisoen by KIPTS) voorgekom. Twee interessante, dog onverklaarbare, verskynsels is waargeneem: stervormige erosie aan die onderkante van die skerms van die HTV-SR isolators op GS+ en material-afskilfering by die skerm-skede tussenvlak van die HTV-SR isolators op GS-. Hierdie verskynsels vereis verdere ondersoek ten einde moontlike verklarings vas te stel.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The electromagnetic and mechanical design aspects of an optimally designed double-sided rotor radial flux permanent magnet wind generator with non-overlap iron-cored stator windings are analysed in this thesis. The generator topology proposed in this study aims to reduce the strength demand on the generator structural support, caused by the magnetic attraction forces between the rotor and stator iron components, and in so doing reducing the overall generator mass. The proposed design has very good cooling properties. Compared to a conventional iron-cored permanent magnet generator and an air-cored permanent magnet generator, the double-sided rotor iron-cored topology performs the best with reference to mass and efficiency. / AFRIKAANSE OPSOMMING: Die elektro-magnetiese en meganiese ontwerp-aspekte van ‘n optimal ontwerpte tweesydige rotor radial-vloed permanente magneet windgenerator met nie-oorvleulende ysterkern statorwindings word in hierdie tesis ontleed. Met die generator topologie wat in hierdie studie voorgestel word, word beoog om die strukturele materiaal wat vir die generator benodig is te verminder. Die magnetise aantrekkingskragte tussen die yster komponente van die rotor en stator word dus aangespreek in hierdie studie, om sodoende ook die algehele massa van die permanente magneet generator te verminder. Die voorgestelde tweesydige-rotor ontwerp het baie goeie verkoelings eienskappe en het ‘n kleiner massa en hoër effektiwiteit as beide ‘n konvensionele ysterkern generator met ‘n enkelsydige-rotor en ‘n tweesydige-rotor lugkern permanente magneet generator met dieselfde drywingsvermoë.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Although regenerative braking has been in used in railway systems for a long time already, the energy generated was dissipated in resistor banks. The rapid advances in the power electronics field, accompanied by the development of faster and higher power switching devices in recent years, now make it possible to convert the regenerated electrical energy from DC to AC, which can then be injected into the Eskom grid. A 1.5 MW full scale prototype system was built, installed and tested in a Spoornet DC traction substation. A seven level series-stacked converter topology was used along with a specially designed injection transformer. The system was controlled by the PEC 33 controller board, which was developed at the University of Stellenbosch. The primary function of the system is to function as a regeneration converter and as a secondary function act as an active power filter.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / Electrification of rural areas is one of the biggest challenges faced by ESKOM and methods are required to extend medium voltage distribution lines to these often remote areas. As loads increase due to line-extension, in-fills and energy theft, maintenance cost and life expectancy of distribution and power transformers becomes more critical. The thesis addresses these two aspects with the development of a self regulated and protected electrification transformer that makes use of current, voltage and ambient temperature measurements to regulate voltage and protect hardware from overloading. The design of the hardware that allows the system to run at 200% load without decreasing the lifetime of the transformer is examined. Temperature estimation techniques are used to estimate the temperatures in the 16 kVA, 22 kV to 230 V, distribution transformer to run above nameplate ratings without causing damage. The control of the system is implemented on TMS320F2812 digital signal processor from TI that is DSP/BIOS compatible. The control software is implemented using DSP/BIOS, which allows real-time scheduling and monitoring of procedures. Furthermore a distribution transformer was fitted with temperature sensors and heat run tests were performed. The results of the temperature tests were used to verify the estimation techniques and to determine constants used for temperature estimation.

Thesis (MEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / Autonomous rendezvouz and docking is seen as an enabling technology. It allows, among others, the construction of larger space platforms in-orbit and also provides a means for the in-orbit servicing of space vehicles. In this thesis a docking sequence is proposed and tested in both simulation and practice. This therefore also requires the design and construction of a test platform. A model hovercraft is used to emulate the chaser satellite in a 2-dimensional plane as it moves relatively frictionlessly. The hovercraft is also equipped with a single camera (monocular vision) that is used as the main sensor to estimate the target’s pose (relative position and orientation). An imitation of a target satellite was made and equipped with light markers that are used by the chaser’s camera sensor. The position of the target’s lights in the image is used to determine the target’s pose using a modified version ofMalan’s Extended Kalman Filter [20]. This information is then used during the docking sequence. This thesis successfully demonstrated the autonomous and reliable identification of the target’s lights in the image, and the autonomous docking of a satellite pair using monocular camera vision in both simulation and emulation.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / Electrical energy is continuously transported across the world by high voltage transmission lines. These transmission lines are however subject to losses beside the inherent resistive and dielectric losses. This additional loss phenomenon is described as corona. The CSIR has developed an optical system to detect the radiation caused by the corona so that preventive measures can be taken to reduce these losses. The corona mechanism and how it results in measurable radiation is explored and the structure of the optical system is analyzed. The optical emissions detected by the present optical system offer no indication of the severity of the corona discharge. This issue is addressed in this thesis as correlations are sought between the illuminated pixels displayed on the camera’s display and physical quantities. A blackbody is employed to find a correlation between these illuminated pixels and radiation. Deviations from the correlation drawn is explored regarding the saturation mechanisms of the optical system and the distance from the blackbody. A corona cage is next employed to find a correlation between the illuminated pixels and electrical corona loss, a quantity indicative of the severity of corona losses on a transmission line. Further tests are also performed at a reduced gain as it was discovered that the optical system’s response is more linear at reduced gain than at full gain. It is also indicated that this usage of reduced gain does not have a detrimental effect on the sensitivity of the optical system. The corona cage measurement employs a small spheric source which is taken as a base measurement against which all other measurements can be compared. The deviation of this base analogy is explored against deviations in the corona discharge geometry used, the prevalent weather condition, and the saturation of the optical system itself. Both the corona cage and blackbodies used are quite bulky pieces of laboratory equipment. The use of a smaller, more portable calibration source is therefore also explored. A literature study is made of lasers, lamp sources, and laser diodes that can be employed as a more portable calibration source. The final choice of calibration source is shown to be a lamp source. Tungsten calibration lamps are explored in depth and a circuit is designed to keep the radiation from a lamp source constant in order to improve on its ability as a calibration source.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / This thesis discuss an investigation into the applicability of modern high frequency power conversion technology in the plasma mineral processing industry. The physics governing the plasma in a processing environment are analysed to provide a clear understanding of this plasma as electrical load. This was done to create an electrical model for the plasma as load and gain understanding into the electrical supply requirements. Modern high frequency power conversion technology is contrasted with thyristor controlled line frequency technologies to provide a suitable starting point for the study. A 3 kW soft switched converter is proposed for application with a plasma load. This converter is designed and verified. The small-signal signature of the proposed converter under peak current mode control is investigated and a new model is proposed to describe this control configuration.