Using COMSOL Multiphysics® for the Development of an Arc Synchronous Motor with a Halbach Wheel Rotor

R. Anderka[1], A. Jocas[1], A. Vasudevan[1]
[1]University of Edinburgh, United Kingdom
Published in 2019

Hyperloop is a theoretical high-speed mass transportation system which aims to increase efficiency through the use of low-pressure tunnels and contactless propulsion. The University of Edinburgh’s Hyperloop Team (HYPED) has been selected to participate in the SpaceX Hyperloop Pod Competition for the third consecutive year and will be competing against 20 other teams from all around the globe.

This year HYPED presents a significantly improved propulsion module using our own concept arc permanent magnet synchronous motor (APMSM). Our motor works as a magnetic propulsion system similar in principle to a linear induction motor (LIM) but eliminates the need for stator-side magnetizing flux and current, thus increasing the power factor significantly. In particular, the module integrates an electrodynamic wheel, which is used to accelerate our prototype pod and simultaneously functions as the rotor of the APMSM, and a custom designed arc stator. This removes the need for an external motor, resulting in a module that is more compact by volume and mass than the previous Halbach wheel propulsion system, which was driven by external synchronous motors.

COMSOL Multiphysics® simulations played a crucial part in the design process of the module. The Structural Mechanics Module was used alongside the Optimization Module in order to minimize the mass of the propulsion system while keeping the same structural integrity. The AC/DC Module was used to evaluate and optimize the magnetic flux densities of multiple different Halbach array configurations, allowing for rapid prototyping of the rotor. These results were used to decide on a 45-degree offset between the magnets of the Halbach array, allowing for a significant increase in magnetic flux density on the outside of the wheel and an almost complete cancellation of the magnetic field on the interior. By integrating the Electrical Circuit interface with the Rotating Machinery, Magnetic interface, ‘Delta’ and ‘Star’ coil configurations were tested and optimal parameters for the stator were determined. Further, a COMSOL Multiphysics® model was compared to an analytical MATLAB® model based on the research of Paudel and Bird [1]. The whole trajectory of the pod was modeled using the LiveLink™ for MATLAB® Module and custom lookup tables for the thrust force and power losses dependent on different slip and velocity values generated using COMSOL Multiphysics®. Consequently, as the reciprocal electrodynamic wheel interaction and cogging torques were included, more realistic results were obtained. [2] COMSOL Multiphysics® Client-Server mode was used for highly computationally expensive simulations.

References:

[1] Paudel, N. and Bird, J.Z., 2012. General 2-D steady-state force and power equations for a traveling time-varying magnetic source above a conductive plate. IEEE Transactions on Magnetics, 48(1), pp.95-100.

[2] W. Xiaoyuan; G. Peng; W. Gengji, 2013. The design of Halbach array permanent magnet for In-wheel motor. International Conference on Electrical Machines and Systems (ICEMS).

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