Permanent magnet thrust bearings for flywheel energy storage systems: Analytical, numerical, and experimental comparisons

Abstract

A new type of flywheel energy storage system uses a magnetic suspension where the axial load is provided solely by permanent magnets, whereas active magnetic bearings are only used for radial stabilization. This means that the permanent magnet bearing must provide all the axial damping. Furthermore, it must have as low a negative radial stiffness as possible to reduce the workload on the radial active magnetic bearings. Many different mathematical models for determining force, stiffness, and damping of permanent magnet bearings are available in the literature. This work will further develop the most applicable analytical and numerical methods in order to make them directly implementable for designing permanent magnet thrust bearings for flywheel energy storage systems. The outcome is a fast and efficient method for determining force, stiffness, and damping when the bearing setup contains magnetic materials with relative permeability higher than one as well as when it does not. The developed method is validated against numerical and experimental results with good agreement.

A conical passive magnetic bearing with constant stiffness

“…The computational volume is chosen large enough that the boundaries of the simulation volume do not affect the calculations and a fine enough mesh is chosen that the results are verified not to vary when further increasing the mesh size. As we consider an axi-symmetric model, the simulations are 2D, and a very high mesh resolution can be used, eliminating the known convergence issues with bearing finite element models in 3D 6 . As the system modelled is a magnetostatic system, the finite element modeling approach is known to fully reproduce the field created by experimental setups.…”

“…Ref. 6 . To validate the models experimental setups for testing bearings both concentric and off-centre have been presented 7 , 24 , 30 , 39 .…”

Future Trends and Aging Analysis of Battery Energy Storage Systems for Electric Vehicles

“…Finally, the study offered correlations and possible solutions for future investigations. The further grouping of ESSs is investigated in this paper [30], including the advantages and disadvantages of all types of ESS and their building, electric-based qualities, and usage.…”

Multi-objective optimization design of novel differential permanent magnet spring based on analytical modeling

“…Safaeian and Heydari 24 performed a complete analytical method based on dynamic modeling to calculate stiffness and axial, radial and rotational damping coefficients of compact PM rings. Dagnaes-Hansen and Santos 25 presented several different mathematical models for determining forces, stiffness and damping of PM rings. Besides, the analytical models of permanent magnet with other shapes were also proposed, such as cylinders, [26][27][28] spherical, 29 cones, 30 and Halbach array.…”