Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Slip-synchronous permanent magnet generators (SS-PMG) is a recently proposed direct-grid connected direct-drive generator topology for wind power applications. It combines a permanent magnet synchronous generator and a slip permanent magnet generator through a common permanent magnet rotor. In this study the possibility of using an eddy current coupling as the slip permanent magnet generator is investigated. The eddy current coupling has the attractive advantage of completely removing cogging and load torque ripple, which are known problems in the SS-PMG. However, the analytical modelling of the eddy current coupling is complex. Three different topologies are considered for the eddy current coupling. A finite element model is presented for the eddy current coupling. It is shown that 2D finite element methods are inaccurate compared to 3D finite element methods when solving eddy currents in eddy current couplings. In order to test the accuracy of the finite element modelling of a large eddy current coupling a prototype slip rotor is designed to operate with an existing permanent magnet rotor. Two topologies are optimally designed and compared for the slip rotor, using 3D finite element transient simulations. One of the designed topologies is used for the construction of the prototype slip rotor. The manufactured eddy current coupling allows for comparison between the 3D finite element simulations and measured results, which shows an excellent correlation. Based on observations of the 3D finite element simulations an analytical approximation of the eddy current coupling is proposed for low slip frequencies. It is shown that the analytical model is very dependent on the accurate modelling of the eddy current paths in the slip rotor, something that is difficult to determine accurately. An approximation is made, again based on 3D finite element simulations, which allows the accurate modelling of the current paths for different axial lengths. The analytical model is used for rapid design optimisation of both the slip rotor and permanent magnet rotor of the eddy current coupling, for two different eddy current coupling topologies. The optimised eddy current coupling design with the best results is compared to existing slip permanent magnet generator technologies. The eddy current coupling is shown to have the potential to be a feasible alternative to existing slip permanent magnet generator topologies for application in slip-synchronous permanent magnet generators. It has excellent torque versus slip behaviour, and no cogging or load torque ripple. However, the manufacturing and assembly process of the proposed slip rotor has to be improved for the eddy current coupling to be a realistic competitor to the existing slip permanent magnet generator technologies. / AFRIKAANSE OPSOMMING: Die glip-sinkroon permanente magneet generator is ʼn direk-aangedrewe wind generator wat direk aan die krag netwerk gekoppel kan word. Dit kombineer ʼn permanente magneet sinkroon generator en ʼn permanente magneet glip generator deur middel van ʼn gemeenskaplike permanente magneet rotor. In hierdie studie word die moontlike gebruik van ʼn werwelstroom skakel as plaasvervanger vir die permanente magneet glip generator ondersoek. Die werwelstroom skakel het geen vertandings of las draaimoment rimpeling nie, wat bekende probleme vir die glip-sinkroon permanente magneet generator is. Die analitiese modellering van die werwelstroom skakel is egter nie eenvoudig nie. Daar word drie verskillende topologieë oorweeg vir die werwelstroom skakel. ʼn Eindige element model word ontwikkel vir die werwelstroom skakel. Dit word bevind dat 2D eindige element analise onvoldoende is vir die berekening van werwelstrome in die werwelstroom skakel, en gevolglik word 3D eindige element modelle gebruik in hierdie studie. Om die akkuraatheid van die eindige element model te beproef word ʼn prototipe glip rotor optimaal ontwerp deur middel van eindige element analise. Die glip rotor vorm saam met ʼn bestaande permanente magneet rotor ʼn werwelstroom skakel. Vir hierdie ontwerp word twee werwelstroom skakel topologieë gebruik, en met mekaar vergelyk. Die topologie wat beter presteer word gebruik vir die vervaardiging van die glip rotor. ʼn Vergelyking van die gemete waardes van die vervaardigde werwelstroom skakel en die resultate van die 3D eindige element simulasies dui daarop dat die 3D eindige element modellering ʼn baie goeie voorspelling van die werklikheid is. ʼn Analitiese model vir die werwelstroom skakel onder lae glip toestande is ontwikkel deur gebruik te maak van observasies uit die 3D eindige element simulasies. Die analitiese model is baie afhangklik van die modellering van die werwelstrome se stroompaaie, iets wat moeilik is om akkuraat te bepaal. ʼn Benadering word gemaak wat die akkurate modulering van die stroompaaie moontlik maak vir verskillende aksiale lengtes. Die analitiese model word dan gebruik vir vinnige optimering van die werwelstroom skakel se ontwerp vir twee verskillende werwelstroom skakel topologieë. Die geoptimeerde ontwerp wat die beste resultate toon word vergelyk met bestaande permanente magneet glip generators. Dit word gewys dat die werwelstroom skakel die potensiaal het om ʼn uitvoerbare alternatief tot die permanente magneet glip generator te wees, vir gebruik in glip-sinkroon permanente magneet generators. Die werwelstroom skakel toon baie goeie draaimoment teenoor glip gedrag, en het geen vertandings of las draaimoment rimpeling nie. Voordat die werwelstroom generator ʼn realistiese kompeteerder teenoor die bestaande glip-sinkroon tegnologie is, moet daar verbeterde vervaardigings maniere gevind word vir die voorgestelde glip rotor.

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 1997. / This dissertation considers the feasibility of using atmospheric drag to control constellations of micro-satellites in low Earth orbits. The constellation control requirements include an acquisition phase and a maintenance phase. Optimal strategies are designed to control the relative positions of the satellites during these two phases. It is shown that the feasibility and success of the strategies depend on many factors, including the satellite properties and orbital configuration. A nominal test constellation is presented and used as a generic example for the application of the control strategies. The dissertation also focuses on the accurate modelling and simulation of a typical low Earth orbit satellite, moving under the influence of a variety of significant orbit perturbation forces. The simulations form an integral part of the study and are used to verify the application of all the proposed control strategies.

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The focus of this thesis is on the optimal design, control and evaluation of 3-phase permanent magnet radial flux synchronous machines with non-overlapping, concentrated-coil, double layer stator windings for EV hub drive applications. A simple analytical method is developed that can be used as a first design tool. The method uses and predicts the MMF harmonic content for a certain pole-slot combination as well as the harmonic content for the air gap permeance function. These harmonics are then used to calculate the torque and torque ripple of machines with large stator slot openings and surface mounted permanent magnets. A different approach to calculate the iron, stator copper eddy current and magnet losses is presented. This method specifically looks at the machine during field weakening operation when the flux paths are changing in the machine. Flux density information throughout the machine is extracted from a series of static FE solutions, to calculate the losses and to combine this with an empirical formula. Some machine topology choices are compared for use as hub drives in small electric ve- hicles. The parameters that influence the machine design are discussed and evaluated after a multidimensional design optimization is done and an efficient control algorithm is imple- mented. The algorithm works through the entire operating speed range and make use of, automatically generated, 2D look up tables to determine the correct current reference. A stator lamination design is proposed, that combines the use of rectangular preformed coils and semi-closed stator slots. Two prototype machines, one with a good winding factor and the other with a low winding factor, are built and compared. The manufacturing and testing of the two prototype machines are described and shown in detail. / AFRIKAANSE OPSOMMING: Die fokus van hierdie tesis is op die optimale ontwerp, beheer en evaluasie van 3-fase per- manent magneet radiale vloed sinchroon masjiene met nie-oorvleuelende, gekonsentreerde, dubbel laag stator wikkelinge vir EV hub motor toepassings. ’n Eenvoudige analitiese metode is ontwikkel wat as ’n eerste ontwerp gereedskap stuk gebruik kan word. Die metode gebruik en voorspel die MMF se frekwensie inhoud vir ’n sekere pool-gleuf kombinasie sowel as die frekwensie inhoud vir die lug spleet permeansie funksie. Hierdie frekwensie inhoud word dan gebruik om die draaimoment en draaimoment riffel van masjiene met groot stator gleuf openinge en oppervlak magnete te voorspel. ’n Ander benadering om yster, stator koper werwel stroom en magneet verliese te bepaal word voorgestel. Hierdie metode kyk spesifiek na masjiene onder veld verswakking beheer wanneer die vloed paaie verander vanaf die normale. Die vloeddigtheid, regdeur die masjien, word verkry deur om van ’n reeks statiese eindige element oplossings gebruik te maak en dit te kombineer met ’n empiriese verliesberekening. Die parameters wat die masjienontwerp beïnvloed, word bespreek en geëvalueer na ’n mul- tidimensionele ontwerp optimering gedoen is en ’n effektiewe beheer algoritme geïmplimen- teer is. Die algoritme werk vir enige spoed en is gebaseer op die outomaties gegenereerde 2D opsoek tabelle wat die korrekte stroomverwysing gee. ’n Stator laminasie ontwerp word voorgestel wat die gebruik van vooraf vervaardigde spoele en gedeeltelik toe stator gleuwe moontlik maak. Twee prototipe masjiene, een met ’n goeie windingsfaktor en een met ’n swakker windingsfaktor is gebou en vergelyk. Die ver- vaardiging en toetsing van die twee prototipe masjiene word in detail beskryf en gewys.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The slip synchronous-permanent magnet generator (SS-PMG) is a direct-driven, direct-to-grid generator for wind turbine applications. This investigation focuses on achieving automated grid connection and low voltage ride-through for a small-scale SS-PMG. To reduce cost and complexity, components such as blade pitch controllers and frequency converters are avoided. Instead, electromagnetic braking is employed to control turbine speed prior to grid synchronisation and compensation resistances are used to facilitate grid fault ride-through. The conditions under which the SS-PMG can be successfully synchronised with the grid are determined, indicating a need for speed control. An evaluation of electromagnetic braking strategies reveals that satisfactory speed control performance can be achieved when employing back-to-back thyristors to switch in the braking load. Simulations show that controlled synchronisation can be executed successfully under turbulent wind conditions. All controllable parameters are held within safe limits, but the SS-PMG terminal voltage drop is higher than desired. Compensation is developed to allow the SS-PMG to ride through the voltage dip profile specified by the Irish distribution code. It is found that a combination of series and shunt resistances is necessary to shield the SS-PMG from the voltage dip, while balancing active power transfer. The flexibility offered by thyristor switching of the shunt braking load is instrumental in coping with turbulent wind conditions and unbalanced dips. The South African voltage dip profile is also managed with conditional success. Following on from the theoretical design, the grid connection controller is implemented for practical testing purposes. Protection functions are developed to ensure safe operation under various contingencies. Before testing, problems with the operation of the thyristors are overcome. Practical testing shows that grid synchronisation can be undertaken safely by obeying the theoretically determined conditions. The speed control mechanism is also shown to achieve acceptable dynamic performance. Finally, the SS-PMG is incorporated into a functioning wind turbine system and automated grid connection is demonstrated under turbulent wind conditions. Future investigations may be focused on optimal control strategies, alternative solid-state switching schemes, and reactive power control. Low voltage ride-through should also be optimised for the South African dip profile and validated experimentally. / AFRIKAANSE OPSOMMING: Die glip-sinchroon permanente magneet generator (GS-PMG) is ‘n direkte dryf, direkte netwerkgekoppelde generator vir windturbine toepassings. Hierdie ondersoek fokus op die bereiking van ’n ge-outomatiseerde netwerkkoppeling en lae spanning deurry vir ‘n kleinskaalse GS-PMG. Om kostes en kompleksiteit te verminder, word komponente soos lemsteekbeheerders en frekwensie-omsetters vermy. In plaas daarvan word elektromagnetiese remwerking gebruik om die turbine spoed, voorgaande net-werksinchronisasie, te beheer, en word kompensasieweerstande gebruik om netwerkfoutdeurry te handhaaf. Die omstandighede waaronder die GS-PMG suksesvol met die netwerk gesinchroniseer kan word, is vasgestel en dit het die behoefte aan spoedbeheer uitgewys. ‘n Evaluering van elektromagnetiese remstrategië wys uit dat ’n bevredigende spoedbeheervermoë verkry kan word as anti-parallelle tiristors gebruik word om die remlas te skakel. Simulasies wys dat beheerde netwerksinchronisasie suksesvol uitgevoer kan word, selfs onder turbulente windtoestande. Alle beheerbare parameters is binne veilige perke gehou, maar die GS-PMG se klemspanningsval is gevind as hoë as verwag. Kompensasie is ontwikkel om die GS-PMG toe te laat om deur die spanningsvalprofiel, soos gespesifieer deur die Ierse distribusiekode, te ry. Dit is gevind dat ‘n kombinasie van serie- en parallelle weerstande nodig is om die GS-PMG teen die spanningsval te beskerm, terwyl aktiewe drywingsoordrag gebalanseer word. Die buigbaarheid wat verkry word met die tiristorskakeling van die parallele weerstand is noodsaaklik in die hanteering van turbulente windtoestande en ongebalanseerde spanningsvalle. Die Suid-Afrikaanse spanningsvalprofiel is ook met voorwaardelike sukses hanteer. In opvolg van die teoretiese ontwerp is die netwerkkoppelingsbeheerder vir praktiese toetsdoeleindes in werking gestel. Beskermingsfunksies is ontwikkel om veilige werking onder verskeie gebeurlikhede te verseker. Die probleme met die werking van die tiristors is oorkom voor die aanvang van die toetse. Die praktiese toetse bewys dat netwerksinchronisasie veilig gedoen kan word deur die teoretiese bepaalde voorwaardes te volg. Dit is ook getoon dat met die spoedbeheermeganisme aanvaarbare dinamiese gedrag verkry kan word. Ten laaste is die GS-PMG in ‘n werkende windturbinestelsel geïnkorporeer en outomatiese netwerkkoppeling is onder turbulente windtoestande gedemonstreer. Toekomstige ondersoeke kan toegespits word op optimale beheerstrategië, alternatiewe vaste toestand skakelingskemas en reaktiewe drywingsbeheer. Lae spanning deurry moet nog vir die Suid- Afrikaanse spanningsprofiel ge-optimeer en eksperimenteel bevestig word.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In the last century the earth has experienced an increase in the global mean temperature, with the main contributing factor being the increase in greenhouse gasses. Evidence indicates that the burning of fossil fuels, critical in the supply of energy, contributed towards three quarters of the carbon dioxide (CO2) increase. In 2008 South Africa reached electricity capacity constraints. A subsequent economic downturn experienced in the country, brought about by the worldwide economic recession, has relieved some of the strain on the electricity supply system. However, consumption levels are returning to those experienced during 2008 and no new base load power stations have been added. Short-term capacity constraints can be managed by shifting the peak demand, but the electricity shortage can only be avoided by adding additional capacity or reducing the overall electricity consumption. Supply-side solutions are both overdue and too expensive. The only solutions that can provide lasting results are demand-side solutions. During the past few years the Energy Efficiency and Demand-side Management (EEDSM) programme implemented by South Africa’s electricity supply utility, Eskom, has gained prominence. This programme relies heavily on calculating the savings incurred through any demand-side intervention. Energy audits enable the calculation of various consumption scenarios and can provide valuable insight into load operation and user behaviour. Energy audits involve a two-part procedure consisting of load surveying and an analysis. This thesis describes the development of both these procedures, combined into a single application. The application has been tested and provides an accurate and effective tool for simulating consumption and quantifying savings for various load adjustments. The results gained from the auditing application surpassed the expectations and provides the user with a sufficient base-line consumption estimate. The results do not reflect day-to-day variations, but the simulations are sufficient to quantify savings and determine whether demand-side interventions are financially viable. The application also presents a benchmark for the type of applications required to successfully implement an EEDSM programme. / AFRIKAANSE OPSOMMING: In die afgelope eeu het die aarde se gemiddelde temperatuur toegeneem, met die toename in kweekhuisgasse as die grootste bydraende faktor. Dit wil ook voorkom asof die verbranding van fossielbrandstowwe, wat noodsaaklik is vir die verskaffing van energie, verantwoordelik is vir driekwart van die toename in koolstofdioksied (CO2). Gedurende 2008 het Suid-Afrika elektrisiteitsbeperkings bereik. Die daaropvolgende ekonomiese afswaai wat in die land ervaar is weensdie wêreldwye ekonomiese resessie, het van die druk op die elekriese netwerk verlig. Verbruikersvlakke is egter besig om terug te keer na waar dit in 2008 was, maar geen nuwe basislas-kragstasies is gebou nie. Op die kort termyn kan die kapasiteitsbeperkings bestuur word deur die aanvraag te verskuif, maar die elektrisiteitstekort kan op die lang duur slegs vermy word deur bykomende kapasiteit by te voeg of die totale aanvraag te verminder. Toevoerkant-oplossings is beide agterstallig en te duur. Die enigste oplossings wat blywende resultate kan lewer, is dus aan die verbruikerkant. In die afgelope paar jaar het die effektiewe bestuur van energieverbruik baie aansien geniet. Die nasionale energievoorsiener, Eskom, het ook 'n program geloods om te help met die implimentering van energiebesparingmaatreëls. Die implementering van energie-oudits om met die kwantifisering van besparings te help, is van integrale belang vir die sukses van die program. Energie-oudits stel die eindverbruiker in staat om verskeie verbruiksmoontlikhede te beproef en sodoende waardevolle inligitng te verkry rakende die verbruikspatrone van die fasiliteit. Energie-oudits behels 'n tweeledige proses, bestaande uit 'n lasopname en 'n verbruiksanalise. Hierdie proefskrif beskryf die ontwikkeling van 'n stelsel wat beide die prosesse kombineer in 'n enkele applikasie. Die applikasie is getoets en bied 'n akkurate en doeltreffende instrument om verbruik te simuleer en besparings te kwantifiseer vir verskeie verbruiksmoontlikhede. v Die resultate van die oudit het die aanvanklike verwagtinge oortref en voorsien verbruikers van 'n goeie skatting van die basisverbruik van 'n fasiliteit. Die resultate weerspieël nie dagtot- dag variasies nie, maar die simulasies is voldoende om besparings te kwantifiseer en help om die finansiële lewensvatbaarheid van verbruikerskant-intervensies te bepaal. Die program bied ook 'n verwysingspunt vir applikasies wat besparingstudies wil implementeer.

The Eskom Transmission Network experiences an exceptionally high number of line faults, the cause of which, may not be correctly identified. This thesis analyses a number of all the possible factors responsible for causing these faults. The objective is to assign probable causes of these faults and that the correct preventative or corrective measures may be planned. The percentage of unexplained line faults is estimated to be 35 % of the total system faults. It is important for the Transmission Group of Eskom to minimise the number of faults. Major efforts to minimise identified faults such as bird streamers, veld fires, sugar cane fIfes, lightning and a hypothesised light pollution, light wetting mechanism has been undertaken by the transmission grid authority. This thesis presents an analysis of the statistical data of the unknown faults (unknown faults is defined as lines that trip due to a reason which could not be identified) that has been undertaken. This analysis takes into account a number of categories of causes of line faults. The period, for which the performance of the lines was analysed for was the years inclusive of 1993 to 1997. The investigation has focused on the identification of the under-performing lines of the main Transmission Network. The identified poorly performing lines have been compared with each other from the perspective ofthe following variables: • Region • Voltage (System Voltage) • Climatic Data Line faults - Time ofDay analysis • Line Faults - Time of Year analysis. The analysis indicates that the majority of unexplained flashovers occur between 22 :00 and 07:00 the following morning (Britten et al, 1999). Almost all of the under performing lines in South Africa fall in the sub-tropical/humid climatic area. All the lines studied are insulated with standard glass disc insulators. The analysis indicated that most of the unexplained line faults occur during the months when the seasons change, e.g. from autumn to winter. The analysis further indicates that most unexplained line faults occurred during the months of April to May and August to September. Of note is that during the period of this investigation bird guarding was performed on some lines. Installing bird guards may reduce those line faults that are caused by bird streamers. However, the bird pollution (deposited on glass disc insulators) that is not washed off at the same time as the bird guard installation may cause the line to trip due to the combination of the pollution and wetting resulting in a pollution type flashover. This is a possible cause of some unexplained line faults that occur from April to May. Bird streamers are also identified as the most probable cause of the unexplained faults which occur during the late evening periods (22:00 - 00:00). Pollution (with wetting) during the early morning periods may result in faults for the period 00:00 to 02:00. Line faults in the early morning periods (04:00 - 7:00) could be due to bird streamers or pollution and wetting, depending on the time of year in which the faults occurs. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

Abstract available in digital copy. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

EThekwini Electricity (EE) purchases its energy on the Megaflex tariff from Eskom which has had considerable changes in content over the years. This has caused the present tariffs offered by EE to move away from cost reflectivity. Structural changes over the years have caused distortion to even the supposedly cost reflect ‘Time of Use’ tariff (TOU) which emulated Eskom’s previous Large Power Users (LPU) tariffs. The divergence between the purchase of electricity and the method of recovery for the sales becomes a cause for concern. This opens EE to risk of not being able to offer cost reflective tariffs and diminish risks in recovery via the tariffs. This has an impact on the budgeted revenue. The primary intention of this study was to establish a formalised procedure and to develop a methodology that Ethekwini Electricity (EE) can use for the review of their tariffs. This study was necessary and extremely crucial for the mitigation of financial risk when tariffs are reviewed and restructured since the revenue recovered via the tariffs are in excess of 5 billion rand per annum. The study consisted of the development of a methodology which consists of a process flowchart and a series of Excel spreadsheets in which the analysis was done. The development of the model utilised information that were readily available and data that were extracted and manipulated from installed systems. The objectives were to determine all associated costs for the delivery of electricity, identify cost drivers, determine cost structure and finally determine applicable tariffs for EE. Issues such as customer categorisation, cross subsidisation, cost reflectivity and affordability were taken into account. This model could now be used in the future for tariff increases and applications to the regulator. This methodology was used to design of the 2009/2010 electricity tariffs for Ethekwini Electricity. The outcome of this study resulted in the re-categorisation of EE’s customer base, changes to the tariff structures and the phasing out of the non cost reflective tariffs. This study enabled the restructure of the LPU TOU tariff which was crucial for EE’s cost recovery. It also resulted in the development of two new TOU tariffs for residential and commercial customers. Whilst other municipalities experienced difficulties in recovering their revenue due to Eskom’s restructured Megaflex tariff, EE’s actual revenue differed by 1% when it was compared to the budgeted revenue towards the end of 2009. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The management of parallel and series resonance conditions is important for ensuring that harmonic levels are managed on utility networks, and that shunt compensators are able to operate without constraints for various network conditions (states). For these and similar problems, harmonic impedance assessment of the ac network is required for the design of ac filter or shunt capacitor bank installations. This is particularly important for large installations connected to HV or EHV systems, because resonances at these voltage levels tend to be highly un-damped resulting in potentially damaging voltage and current amplification. The objective of this dissertation was to develop and demonstrate a design methodology which makes use of network impedance assessment methods to provide robust harmonic integration of large shunt compensators into a transmission and HVDC systems. The design methodology has two aspects. The first part considers network modeling, evaluation of different models and simulation of harmonic impedance. In the second part, methods of analyzing and assessing the simulated harmonic impedance are developed. A detailed step-by-step approach was taken in the development of the design methodology. The methodology was documented as a guideline and accompanied by the development of an Excel tool that can be used to assess the simulated harmonic impedance. The Excel tool permits a systematic assessment of the simulated network impedance where shunt compensators are integrated into transmission systems. The tool also ensures that the design of transmission and HVDC ac shunt compensation is optimally robust in terms of harmonic resonances. The theoretical and computational review has been tested and demonstrated on the existing Eskom Transmission system through several case studies. The results have shown the merits of the design methodology. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The digital control of UPS systems has been difficult in the past due to a lack of DSP technology. It was for this reason not possible to establishing the necessary control to regulate the voltages and currents of the UPS systems. Recent advances in DSP technology have however provided the means of establishing central control of the UPS system as well as incorporating more complex closed-loop control algorithms by utilising a single floating-point DSP. Closed-loop control strategies are investigated and the central control of a line-interactive UPS is established in this study. Both the status of the physical system as well as various system parameters are controlled. The system both regulates and charges the storage batteries when the main utility supply is maintained. In the event that the utility fails, the converter instantaneously changes power flow towards the load with the aim of maintaining an uninterrupted voltage supply. Several closed-loop deadbeat based control strategies are investigated for the regulation of the inductor current. A solution for the regulation of the DC-link is also developed and implemented. Furthermore, an intensive study is done on the regulation of the voltage supplied to the load in the event that the utility supply fails. The investigation is initially approached by considering classical control theory. Although these control strategies provided sufficient results, a predictive strategy that is based on the physical conditions of the switching converter is finally investigated to establish closed loop control of the output voltage. This resulted in a high-bandwidth voltage controller capable of maintaining control under a wide-array of load conditions. / AFRIKAANSE OPSOMMING: Die digitale beheer van UPS stelsels was moeilik in the verlede as gevolg van 'n gebrek aan DSP tegnologie. Dit was vir hierdie rede nie moontlik om beheer te kon bewerkstelling ten einde die spannings and strome in the UPS stelsels te kon reguleer nie. Onlangse vordering in DSP tegnologie het egter dit moontlik gemaak om sentrale beheer van die UPS stelsel te bewerkstellig sowel as om meer komplekse geslote lus beheer algoritmes te inkorporeer met behulp van 'n enkele DSP. Geslote lus beheer strategiëe word ondersoek en die sentrale beheer van die line-interaktiewe UPS word bewerkstellig in hierdie studie. Beide die huidige toestand van die fisiese stelsel sowel as die verskeie parameters word beheer. Die stelsel beide laai en reguleer die batterye terwyl die hooftoevoer onderhou word. In die geval dat die hooftoevoer faal, word die omsetter se rigting van drywingsvloei verander om die las te voorsien van 'n ononderbroke spannings toevoer. Verskeie geslote-lus “deadbeat” beheer strategiëe word ondersoek vir die regulasie van die induktor stroom. 'n Oplossing vir die regulasie van die GS-koppervlak word ook ontwikkel en geïmplementeer. Verder word 'n intensiewe studie gedoen op regulasie van die spanning wat aan die las gevoer word in die geval dat die hooftoevoer faal. Hierdie ondersoek word aanvanklik benader deur klassieke beheer teorie te bestudeer. Alhoewel hierdie beheer strategiëe voldoene resultate gebied het, was 'n voorspel beheerstrategie gebaseer op die fisiese toestand van die omsetter finaal ondersoek. Die resultaat is 'n hoë-bandwydte spannings beheerder wat daartoe instaat is om beheer te handhaaf onder 'n verskeidenheid van lastoestande.