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Energies 2017, 10(3), 316;

Reluctance Machine for a Hollow Cylinder Flywheel

Division for Electricity, Uppsala University, Lägerhyddsvägen 1, 75237 Uppsala, Sweden
Author to whom correspondence should be addressed.
Academic Editor: K.T. Chau
Received: 28 October 2016 / Revised: 20 February 2017 / Accepted: 28 February 2017 / Published: 7 March 2017
(This article belongs to the Special Issue Electric Machines and Drives for Renewable Energy Harvesting)
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A hollow cylinder flywheel rotor with a novel outer rotor switched reluctance machine (SRM) mounted on the interior rim is presented, with measurements, numerical analysis and analytical models. Practical experiences from the construction process are also discussed. The flywheel rotor does not have a shaft and spokes and is predicted to store 181 Wh / kg at ultimate tensile strength (UTS) according to simulations. The novel SRM is an axial flux machine, chosen due to its robustness and tolerance for high strain. The computed maximum tip speed of the motor at UTS is 1050 m / s . A small-scale proof-of-concept electric machine prototype has been constructed, and the machine inductance has been estimated from measurements of voltage and current and compared against results from analytical models and finite element analysis (FEA). The prototype measurements were used to simulate operation during maximal speed for a comparison towards other high-speed electric machines, in terms of tip speed and power. The mechanical design of the flywheel was performed with an analytical formulation assuming planar stress in concentric shells of orthotropic (unidirectionally circumferentially wound) carbon composites. The analytical approach was verified with 3D FEA in terms of stress and strain. View Full-Text
Keywords: flywheel energy storage (FES); hollow cylinder flywheel; reluctance machine; high-speed machines flywheel energy storage (FES); hollow cylinder flywheel; reluctance machine; high-speed machines

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Hedlund, M.; Kamf, T.; de Santiago, J.; Abrahamsson, J.; Bernhoff, H. Reluctance Machine for a Hollow Cylinder Flywheel. Energies 2017, 10, 316.

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