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Title: Novel 6-phase fractional-slot permanent magnet machine for electric vehicle applications
Author: Patel, Vipulkumar
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2014
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To tackle the issues concerning the global warming and the international energy security, the only way forward is the wide spread adoption of plug-in electric vehicles (EV) in the transportation industry. High power dense and highly efficient electrical machines pave the way for the swift realization of EV. The research underpinned in this thesis describes the new winding configurations and associated slot-pole combinations for permanent magnet (PM) brushless machines that lead to improved performance and facilitate cost reduction. The current state-of-the-art machine technologies and their topologies are weighed against one another qualitatively through a comprehensive literature survey, and quantitatively by a preliminary design study of the most competitive machine technologies for a micro-sized EV application. Compared to the current state-of-the-art, the salient feature of the proposed winding designs is elimination and/or reduction of undesirable space harmonics which result from the existing fractional-slot per pole per phase PM machines with concentrated windings. This brings the benefits of significant reduction of the eddy current loss in the rotor permanent magnets, shorter end-windings and hence reduced copper loss and copper usage, increased power/torque density, reduction in manufacturing cost, and improved energy efficiency. In order to improve power drivetrain availability for EV applications, the thesis proposes the design of 6-phase PM machine as two independent 3-phase systems using the proposed winding configuration. A number of possible phase shifts between two sets of 3-phase windings due to their slot-pole combination and winding configuration are investigated and the optimum phase shift is selected by analysing the harmonic distributions and their effect on machine performance including the eddy current loss in the magnets. The proposed 6-phase winding configuration is applied to the design of an interior permanent magnet (IPM) machine for segment-A EV, under the electrical, thermal, and volumetric constraints, and demonstrated by a series of preliminary functional tests on the prototype machines. The design study and the measurement results show that the proposed winding configuration results into high torque/power dense PM machine with high efficiency over wide operating range. The important design aspects of the new machine topologies for EV application are investigated in detail, which include effect of phase shifts on magnet eddy current loss and unbalanced magnetic pull of the machine, demagnetization assessment of the new machine topology under various fault conditions, and thermal analyses over the driving cycles.
Supervisor: Wang, Jiabin Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available