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Title:High-frequency, slotless permanent magnet synchronous motor for aircraft propulsion
Author(s):Yoon, Andy K.
Director of Research:Haran, Kiruba S.
Doctoral Committee Chair(s):Haran, Kiruba S.
Doctoral Committee Member(s):Banerjee, Arijit; Jin, Jianming; Krein, Philip T.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Electric airplane, electric machine, high frequency, slotless, litz, halbach, aerospace, high specific power, high power density, flight weight
Abstract:While electric machines have already shown impact in applications where efficiency, reliability, and cost are critical, newer applications are instigating development of next-generation, lightweight, power-dense motors. The benefit of lower weight in a motor is especially attractive when considered for aerospace applications, such as electric propulsion for aircraft. More specifically, significant reduction of weight and/or volume of the propulsor may allow placement of more batteries for increased overall energy storage capability for the aircraft, or reduction in energy needed during take-off or cruising. In fact, recent analysis has shown that hybridization of commercial aircraft could allow up to 33% reduction in fuel consumption, 55% reduction in NOx emissions at cruise, and 60% reduction in NOx emissions during landing and take-off. Furthermore, the National Aeronautics and Space Administration (NASA) has identified lightweight, low-volume electric machines as one of the key enabling technologies. This dissertation details work accomplished in the development of a 1 MW, 13 kW/kg, high-frequency electric machine design for improving specific power density for weight- and/or volume-sensitive applications. Analytical models that correspond to this topology are discussed. Slotless topology is compared to conventional slotted motor topology using the analytical models to show slotless topology's potential for high specific power at higher frequencies. Furthermore, the models are used to show the scalability of the high-frequency, slotless machine at different speeds. The results show that the topology maintains the lightweight characteristics even at lower speeds. The study is extended to include a specific aerospace application, and three possible motor-fan integrations are presented. While the benefit in specific power density is highlighted, the proposed slotless, cantilevered rotor topology is sensitive to manufacturing tolerances. Particularly, the low reactance of the motor and the slotless structure contributes to the increase in circulating current in the armature coils. The aforementioned analytical model is used to predict the imbalance in back-EMF and thus the circulating current due to the manufacturing tolerances, and a low- field rotor is constructed to verify the prediction. The experimental measurements point to shortcomings of the rotor eccentricity model in predicting the circulating current in the coils. The relationships between manufacturing tolerances in coils and circulating current are highlighted.
Issue Date:2019-11-18
Rights Information:Copyright 2019 Andy K. Yoon
Date Available in IDEALS:2020-03-02
Date Deposited:2019-12

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