Design of a PM Synchronous Motor for an Integrated Light EV Motor Drive Application
Date
2024-12
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Stellenbosch : Stellenbosch University
Abstract
Light electric vehicles (LEVs) have gained prominence as an appealing mode of transportation across diverse driving conditions. The development of these vehicles is driven by the pursuit of enhanced efficiency, reduced volume, and cost-effectiveness. This burgeoning interest in LEVs has prompted the exploration of various drive train options to meet these evolving requirements. This dissertation is dedicated to the investigation and design of a PM synchronous motor specifically tailored for light electric vehicle applications, and ensuring an ease of integration with the other components of the electric drive train. The integral components of the proposed integrated motor drive encompass the magnetic gear, electric motor, and electric drive system, with the electric motor serving as the heart of the system. Many types of design choices are available for the electric motor, and difficulty is generally found on the design optimisation for traction application. Therefore the focus of this dissertation revolves around these design choices, and correctly implementing an optimisation method in order to find a cost effective design. Further, research has shown that certain methods exist in order to achieve high speed applications for traction motors. While existing research emphasizes high-speed traction motor applications using V-shaped rotor designs and intricate control strategies, this work advocates for a more cost-effective solution through the utilization of a surface-mounted permanent magnet (SPM) motor capable of achieving optimal speeds for the particular application. A thorough exploration of various topologies, including rotor choices and winding layouts, for light electric vehicles is undertaken and systematically compared. The findings reveal that a cost-effective SPM motor with an overlapping winding and SPM rotor choice can achieve an extensive high-speed range without compromising on the cost efficiency. This design choice undergoes further scrutiny through unique optimisations employing finite element analysis and a driving cycle approach. A novel flux mapping method is developed, leading to the identification of elongated stator teeth as a strategic enhancement. This design modification improves synchronous inductance, consequently enhancing field-weakening capabilities and thermal efficiency. The culmination of this work emphasizes the effectiveness of the optimisation strategy, demonstrating how an extended field-weakening range can be attained by increasing the slot tooth region. This research contributes valuable insights into achieving a balance between cost-effectiveness and a high-performance design, shedding light on the potential of surface mounted PMs for electric motors to be implemented within light electric vehicles.
Description
Thesis (PhD)--Stellenbosch University, 2024.