published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

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Switched reluctance machines (SRMs) have recently attracted more interest in many applications due to the volatile prices of rare-earth permanent magnets (PMs) used in permanent magnet synchronous machines (PMSMs). They also have rugged construction and can operate at high speeds and high temperatures. However, acoustic noise and high torque ripples, in addition to the relatively low torque density, present significant challenges. Geometry and topology optimization are applied to overcome these challenges and enable SRMs to compete with PMSMs. Key geometric design parameters are optimized to minimize various objective functions within geometry optimization. On the other hand, the material distribution in a particular design space within the machine domain may be optimized using topology optimization. We discuss how these techniques are applied to optimize the geometries and topologies of SRMs to enhance machine performance. As optimizing the machine geometry and material distribution at the design phase is of substantial significance, this work offers a comprehensive literature review on the current state of the art and the possible trends in the optimization techniques of SRMs. The thesis also reviews different configurations of SRMs and stochastic and deterministic optimization techniques utilized in optimizing different configurations of the machine. This thesis introduces a new ON/OFF optimization method based on the line search method to overcome the limitations of the conventional annealing-based ON/OFF optimization. The proposed method shows a faster convergence to optimal solutions than the conventional annealing-based ON/OFF method. The thesis also compares the performance of the generative optimization and the topology optimization of a 6/14 switched reluctance machine with the proposed method and the conventional method. The two methods are applied to two different design domains of the machine for topology and generative optimization and the results are compared to the results of the annealing-based ON/OFF method. The results show the effectiveness of the newly proposed method. A new technique has been introduced in this thesis for reducing the time of calculating stator radial force density waves of switched reluctance machines (SRMs). The method is based on the finite element (FE) simulation of a fraction of an electrical cycle. The new approach shows that a significant time reduction is achieved as compared to the time required for stator radial force density calculation based on the one mechanical cycle simulation method. As the switched reluctance motors introduce new challenges in aspects such as acoustic noise, vibrations, and torque ripples, the method introduced in this helps reduce the time of the optimization process of switched reluctance machines in the design stage to improve the machine performance. The proposed method is applied to radial flux switched reluctance machines. Three different SRMs configurations were used to show the effectiveness of this technique in different force components with minimal error as compared to the benchmark method based on the FE simulation of one mechanical cycle. / Dissertation / Doctor of Philosophy (PhD)