High-performance Electromechanical Conversion Systems Design strategies for variable speed renewable energy generation and computational tools for investigation of iron losses
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SubjectHigh-frequency parameters; Iron losses; Jiles-Atherton model; Homogenization technique; Sensorless control; FEM; Hydroelectric power conversion; Electrical machine; ING-IND/33
The framework of the future energy policies is being changed due to the global warming effects and the efforts in order to reduce the world-wide energy consumption. Since the latter is going to increase due to the third world countries’ development, efficiency improvements in industrial and civil applications have to be functional and cost-effective in order to safe primary energy. It is clear that the electrical energy has a central role in the future energy framework thanks to its flexible generation, transportation and possible storage forms. In the last years, a significant increase of renewable energy production has occurred, not only in order to reduce the CO 2 emissions, but also for the increasing energy demand. However, the production of electrical energy from renewable energy can be in some cases low-efficient due to the non-mature technologies or to the small size of the power plants. In the latter case, it is important to efficiently manage the production system in order to achieve the maximum electrical energy. The purpose of this work is to find a solution for the management of a micro-hydroelectric power plant in order to avoid a specific design of the system, to decrease the manufacture and design costs, and consequently to reduce the pay-back period. Besides the economical aspects, also an efficiency improvement of the production system is required. Therefore, at the beginning, the project focuses on the global aspects of the production system by finding a solution at system level. The solution is to operate the system at variable speed in order to follow the maximum power point at the maximum efficiency. The solution is validated by experimental tests. Afterwards, the electrical machine of the production system is concerned in order to analyze those aspects that can be studied for further improve the efficiency. Thus, the losses of the electrical machine are analyzed and the focus falls on the iron losses which are the most difficult to determine and reduce. In the thesis, the main goal of this part is to find out accurate and precise methods for the estimation of the iron losses. The methods are investigated and validated through experimental results. Finally, another important aspect to further improve a generation system or an industrial system is to avoid position and speed sensors and to operate the system in sensorless control. A part of this thesis is devoted to the determination of the iron losses which are parasitic effects that can be exploited to determine the rotor position. In last part of the project, the investigation of the self-sensing capability of the machine is addressed by including the parasitic effects present in the permanent magnets and in the lamination of the machine. This part wants to give other techniques for the evaluation of the self-sensing capability of an electrical machine by reducing the computational costs.
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