Thesis (MTech(Electrical engineering))--Cape Technikon, Cape Town, 2000 / The development of an automatic frequency control system for a miniature high frequency induction furnace is described. A background study into the fields of induction-heating, resonance, power electronic resonant converters and phase locked-loops are performed with relevance to this research. An analysis of the resonant load circuit is performed by means of a combination of measurement and numerical simulations. The study of the load behavior and power source is used as a :001 to aid effective implementation of the automatic frequency control system. This Jimulation data is used to detenninc the operating frequency range of the RLL system. A background study is performed in whieh several frequency-control schemes for power electronic converters are investigated. A brief summary, in which the basic requirements for a frequency control system with regards to this research are presented. Two revisions of the Automatic Frequency Control system (RLL) were implemented, on the induction furnace. Experimental results on both systems (Revl and Rev2), illustrating the necessity for frequency control are also presented. Future suggestions for optimizing the loop performance are presented. Further steps in the developmental process of the miniature high frequencj induction furnace are also discussed.

Thesis (M. Eng.)(Metallurgical)--University of Pretoria, 2008. / Summaries in Afrikaans and English. Includes bibliographical references.

M.Ing. (Electrical And Electronic Engineering) / The metals manufacturing industry is the link between the mining industry, where the ore is mined, and the manufacturing industries, where metals are utilized to create a wide range of products. Melting processes.are used in the manufacturing of metals from the ore, of which induction melting is one of the possible melting processes. In this study the improvement of induction melting of metals is investigated. A new topology for an induction melting furnace is proposed, and this topology is thoroughly investigated. The induction melting process is influenced by certain user-controlled variables as well as the electromagnetic layout of the furnace. In this study, the influence of these variables on the performance of the furnace are investigated through finite element simulations and insight is also gained into the influence of the electromagnetic layout of the system. An experimental induction melting furnace is described in this study, investigated and compared to the predictions from the simulations. Improvements from structural, thermal and measuring viewpoints are also investigated and implemented.

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