The thesis deals with a special version of diesel welding generator, which consists of a diesel engine, a polyphase welding generator and a self-excited induction generator. We will focus on analysis and possibilities of modifying the latter. Diesel welding generator is used in some special welding processes, because of its specific properties and advantages. With progress in development of high power electronics and its sophisticated control techniques, inverter-based welding machines are being used for the same tasks with increasing frequency. A decrease in demand, because of competitive modern products and some repetitious failures in our current production, started considerations for optimizing the current design.
In the second chapter the working principle of welding generator, its basic characteristics, advantages and disadvantages in comparison to other versions of welding machines are described briefly. The manufacturing process of the treated diesel welding generator is described and the difficulties faced during production and operation. In the continuation our research is limited to analysis and optimisation of an induction generator, because it is a key issue in most technical breakdowns. Its modification would bring the most benefits.
The third chapter encompasses the theory of the induction machine. Working principle and types are described in detail. We familiarized ourselves with the theoretical fundamentals, which will be the base for the analysis using the simulation model.
In the fourth chapter we describe the built-in induction generator of the welding generator and its characteristics. Ideas for possible improvements are discussed. With the intent of reducing the number of different components, the potential of building the induction generator stator windings by using the existing stator laminations of the polyphase welding generator is studied. For the squirrel cage rotor standard laminations out of Kienle + Spiess product catalogue are used. In the study the current configuration and possible altered geometries were simulated, using modern computer-aided tools.
In the fifth chapter some basic traditional design and construction procedures of cage rotor induction motor are described. With their help, the ideas of altering the induction generator geometry are analysed.
In the final chapter we continue the research using Cedrat Flux 2D simulation software. A simulation model of the original induction generator was build and analysed using finite element method (FEM). The results were compared with the measurement performed on the existing generator. This approach verifies our computer model and gives us confidence that it can be used for the calculations and analysis of the generator prototypes with altered geometry. After a comparison between the modified and original design we can evaluate if production of the physical prototype would be reasonable.
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