Date of Award
6-13-2024
Publication Type
Dissertation
Degree Name
Ph.D.
Department
Electrical and Computer Engineering
Keywords
Analytical modeling;Electric vehicles;Finite element analysis;Hairpin windings;Stator winding design;Winding function
Supervisor
Narayan Kar
Supervisor
Jimi Tjong
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Abstract
Transportation electrification is seen as a promising solution to meet future fuel economy requirements and reduce carbon emissions. As a result, the electric vehicle (EV) market is expected to experience significant growth, which requires future electric motors (e-motors) in EVs following their torque-power-speed characteristics, achieving higher torque and power with enhanced efficiency across a wider speed range at lower weight and volume. To meet these objectives, focus should be on crucial design aspects of e-motors, particularly the stator windings. As the heart of the e-motor, stator windings create the revolving magnetomotive force in the airgap converting the electrical energy into the magnetic field, playing a crucial role in enhancing the e-motor’s electromagnetic performance, while minimizing its volume and weight for extending its driving range. Therefore, the goal of this research is to propose an optimal stator winding configuration for traction e-motor using an improved analytical model. The aim is to enhance torque and power efficiency, reduce torque ripples across a wider speed range, and achieve a lighter and more compact stator winding configuration. Towards this research, a traction induction machine (IM) is utilized as the benchmark traction machine, as induction machines are expected to remain a popular choice for automakers in the future as the demand for EVs increases. The research started with the process of developing an experimentally validated improved winding function based (IWFB) analytical model. These include addressing knowledge gaps of frequency-dependent core magnetomotive force (mmf) drops; consideration of simultaneous time and space harmonics effects; and accounting magnetic saturation in various core regions. This improved model calculates the EM performance of the inverter fed traction induction machine in a wider speed range. Additionally, the model is versatile, accommodating different winding types (circular and hairpin windings) to facilitate the exploration of more innovative designs. Thereafter, the IWFB analytical model is used in the optimal winding design process. The processes started with the investigation of various winding configurations to determine a competitive winding configuration to replace the predominately using integer slot distributed windings for improved EM performance across a wider speed range, aiming for shorter winding length and lighter weight. The identified, most competitive variable pitch concentric winding layout, and required coil pitch shifting and a genetic algorithm-based winding turn optimization to make it to exhibit higher torque and power as well as efficiency in the full speed range of the machine, to propose an optimal concentric winding layout. Further, the same design method is applied to propose an optimal concentric winding layout for a commercial traction IM with circular windings. The winding design extends to different stator geometries by varying the number of stator slots, while keeping the machine's pole number constant and altering the winding layers to 1 and 2 to find the optimal winding layout design with circular windings. Then to integrate more versatility and integrate the hairpin winding designs into the design process, while adjusting the developed IWFB model. This introduces a novel concentric winding layout featuring hairpin windings for the baseline traction IM. The primary contribution lies in the proposed hairpin winding layout, which proves superior EM performance over a wider speed range, achieved with lower winding length and weight. Following the comparison of overall performances between concentric winding designs proposed using circular and hairpin windings for the baseline traction IM, the design with hairpin windings demonstrated the overall best performance and is selected as the optimal and novel winding design for the baseline machine, effectively meeting the research objectives Further recommendations for design improvement, future work and analysis will also be summarized towards the end of the dissertation.
Recommended Citation
Guruwatta Vidanalage, Buddhika De Silva, "Stator Winding Design of Traction Machines Using an Extended Winding Function-Based Model for Enhanced Traction Performances" (2024). Electronic Theses and Dissertations. 9407.
https://scholar.uwindsor.ca/etd/9407