Dual air-gap axial flux permanent magnet machines for flywheel energy storage systems

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.

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A Novel Axial-Flux Dual-Stator Toothless Permanent Magnet Machine for Flywheel Energy Storage

Symmetry ◽

10.3390/sym14010061 ◽

2022 ◽

Vol 14 (1) ◽

pp. 61

Author(s):

Yong Zhao ◽

Fangzhou Lu ◽

Changxin Fan ◽

Jufeng Yang

Keyword(s):

Energy Storage ◽

Permanent Magnet ◽

Flux Density ◽

Load Capacity ◽

Core Loss ◽

Torque Ripple ◽

Air Gap ◽

Flywheel Energy Storage ◽

Axial Flux ◽

Permanent Magnet Machine

This paper presents an alternative system called the axial-flux dual-stator toothless permanent magnet machine (AFDSTPMM) system for flywheel energy storage. This system lowers self-dissipation by producing less core loss than existing structures; a permanent magnet (PM) array is put forward to enhance the air–gap flux density of the symmetrical air gap on both sides. Moreover, its vertical stability is strengthened through the adoption of an axial-flux machine, so expensive active magnetic bearings can be replaced. The symmetry configuration of the AFDSTPMM system is shown in this paper. Then, several parts of the AFDSTPMM system are optimized thoroughly, including stator windings, number of pole pairs and the PM parameters. Further, the performance of the proposed PM array, including back-EMFs, air–gap flux density, average torque, torque ripple and over-load capacity, are compared with the Halbach PM array and spoke PM array, showing the superiority of proposed configuration. Finally, 3D simulations were made to testify for the 2D analyses.

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Critical Review of Flywheel Energy Storage System

Energies ◽

10.3390/en14082159 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2159

Author(s):

A.G. Olabi ◽

Tabbi Wilberforce ◽

Mohammad Ali Abdelkareem ◽

Mohamad Ramadan

Keyword(s):

Energy Storage ◽

Permanent Magnet ◽

Storage Systems ◽

Storage System ◽

Energy Storage System ◽

Synchronous Machines ◽

Flywheel Energy Storage ◽

Permanent Magnet Synchronous Machines ◽

Energy Storage Systems ◽

Flywheel Energy Storage System

This review presents a detailed summary of the latest technologies used in flywheel energy storage systems (FESS). This paper covers the types of technologies and systems employed within FESS, the range of materials used in the production of FESS, and the reasons for the use of these materials. Furthermore, this paper provides an overview of the types of uses of FESS, covering vehicles and the transport industry, grid leveling and power storage for domestic and industrial electricity providers, their use in motorsport, and applications for space, satellites, and spacecraft. Different types of machines for flywheel energy storage systems are also discussed. This serves to analyse which implementations reduce the cost of permanent magnet synchronous machines. As well as this, further investigations need to be carried out to determine the ideal temperature range of operation. Induction machines are currently stoutly designed with lower manufacturing cost, making them unsuitable for high-speed operations. Brushless direct current machines, the Homolar machines, and permanent magnet synchronous machines should also be considered for future research activities to improve their performance in a flywheel energy storage system. An active magnetic bearing can also be used alongside mechanical bearings to reduce the control systems’ complications, thereby making the entire system cost-effective.

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