D.Ing. (Electrical and Electronic Engineering) / Solid state converters are showing considerable progress in all applications for power electronics, mainly because of the advances made in the field of power semiconductor devices. Higher frequencies and power ratings of converters are therefore possible, leading to more and more applications for these solid state converters in induction heating. The available knowledge in this fast evolving field is however limited, leading to numerous research possibilities. It is none the less important to learn to crawl before attempting to run and a systematic line is therefore followed in this research. The combination of the heating-coil and work-piece is a challenging electromagnetic problem, resembling a transformer with a short circuited secondary. The heating of the work-piece to above the Curie temperature causes considerable variations in the parameters of the load. A study of the influence of temperature on the physical properties of the heated material is therefore made to obtain an understanding of these variations and is aided by Finite Element Simulations. Numerous circuit topologies and switching strategies are possible candidates for induction heating, and a collection of more than thirty converters is presented. Each of these has its own advantages and disadvantages, of which a good understanding is necessary to obtain the most suitable converter for a certain application in this field. The behaviour of some of the most popular converters under typical load variations is investigated to facilitate the final decision. This knowledge is then applied to some every day applications. A converter is chosen both for an induction cooker and a surface heater, after the specific requirements for each have been identified. A detailed design procedure and experimental results are presented...
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:10790 |
| Date | 16 April 2014 |
| Creators | Koertzen, Henry William Els |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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