Design and Optimization of a Novel Permanent Magnet Synchronous Machine Based on Transverse Flux Topology.

ADEEB, AHMED. Design and Optimization of a Novel Permanent Magnet Synchronous Machine Based on Transverse Flux Topology. (Under the direction of Dr. Iqbal Husain). Rotating electric machines are the primary mean for world energy generation and a major candidate for energy consumption as well. A minute change in the performance of these machines inflicts a large impact in the world energy expenditure. Among different types of electric machines, permanent magnet machines are gaining attention due to their capability of highefficiency operation and compact size. Moreover, recent electrification strategy in the automotive industry, increasing popularity of wind energy harvest and overall desirability of device compactness are creating higher demand for machines with smaller physical footprints. Electric machines are primarily torque producing entity and the compactness of these machines is synonymous with their torque yield capability within a physical constraint or more commonly referred as torque density. When torque density is of concern, a special variant of electric machinesknown as transverse flux machines (TFM) deserve special consideration. These machines are reputed for high torque density operation but have never been popularized due to some limiting factors such as low power factor and consequent increase in drive circuit cost, structural complexities and associated manufacturing cost. The primary target of this research is to perform a thorough investigation in identifying the potentials of this topology over conventional radial flux machines (RFM), recognizing the root sources responsible for causing the limitations and finally addressing the concerns with a systematic approach. The outcome of the in-depth analysis provided the concept of a novel transverse flux topology with substantially improved performance over existing state of the art machines. The topology was built upon strong logical reasoning with the highest emphasis on reducing structural complexities and exclusion of unconventional construction materials otherwise common in existing TFMs. An innovative approach was undertaken to mathematically represent the factors primarily responsible for performance degradation and an objective-function based method was followed for design optimization. Moreover, mathematical analysis of torque ripple harmonic contributions was carried out and design optimization was performed to ensure reasonable performance. As subsidiary works, a mathematical model representing TFM performance was developed which can be an effective tool for thorough investigation of these machines. Finally, a prototype was built which validated the topology benefit and the systematic approach undertaken during the design process. Detailed experiments were performed with the prototype and the performance proved to be in close correspondence with finite element analysis (FEA) results. The machine exhibited high torque density with power factor comparable with conventional permanent magnet machines. During the test procedure, a novel approach was undertaken for accurately separating the loss components and consequent loss comparison with FEA prediction. In conclusion, the research work provided a novel TFM capable of exhibiting high torque density with good power factor performance. The topology relied on conventional motor construction materials such as silicon steel and structural complexity-especially for the moving part was reduced to a negligible extent. Subsequently, the primary concerns of this topology were effectively addressed and the proposed novel TFM brings these machines a step closer to largescale industry adoption.