In an increasingly urgent climate crisis, the use of electric powertrains in smaller,
purpose-built vehicles can expedite the global adoption of electrification. This thesis discusses
the detailed design of an axial-flux switched reluctance motor for application in a light electric
vehicle, such as an E-motorcycle. A vehicle application is studied based on typical driving
conditions in an urban environment. The requirements of the propulsion motor are extracted,
and a baseline machine topology is analyzed for its performance and manufacturability,
towards the goal of a functional prototype. The prototype design includes a self-supporting
foil winding, designed to maximize the use of axial space and allow for good conductive heat
transfer to the machine casing. The rotor structure is found to be a limiting factor, where
maximum speed is limited by the mechanical stresses.
The performance of the motor is analyzed in detail, beginning with a numerical iron
loss model that is implemented to provide faster simulation time of the machine efficiency
than FEA. The efficiency is found to peak at 90%, comparable with other traction motors
of similar size on the market. The switching angles are studied, and the trade-offs between
torque quality and efficiency are quantified over the drive cycle. It was determined that
the vehicle could save 19.6 Wh/km by accepting poor torque quality and operating with
the most efficient control parameters. Thermal analysis is performed to determine the
realistic performance limitations. The machine was found to have power ratings of 7.12
kW instantaneous and 4.76 kW continuous. The final temperature of the winding during the
drive cycle was predicted not to exceed the temperature ratings of the insulation system.
Finally, the prototype is assembled, and a test plan is outlined for qualification of the motor. / Thesis / Master of Applied Science (MASc) / This thesis documents the design of a new type of electric motor that is intended to be used
in a small electric vehicle. The electric motor is different from the majority of motors used
in this application for two reasons: firstly, the motor is a switched reluctance motor, which
means that it does not contain any permanent magnets, offering cost savings and additional
robustness. Secondly, the machine takes the form of a disk, where the magnetic interface
between rotating and stationary components is on the face perpendicular to the axis of
rotation. Normally, electric motors have the magnetic interface on the cylindrical surface
which is parallel to the axis of rotation. The disk form factor presents multiple design
challenges, which when coupled with the switched reluctance motor type, are addressed.
A series of mathematical models are built to predict the performance of the motor in the
vehicular application. Finally, a prototype of the motor is constructed.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26036 |
| Date | January 2020 |
| Creators | Jack Gillies |
| Contributors | Ali Emadi, Berker Bilgin, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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