Design and Analysis of Novel Bearingless Permanent Magnet Synchronous Motor for Flywheel Energy Storage System

Abstract

Abstract-To effectively simplify system structure and improve power density and efficiency, a design for a motor/generator suitable for flywheel energy storage system (FESS) is proposed. The machine is an outer-rotor and coreless-stator-type bearingless permanent magnet synchronous motor (BPMSM) with a Halbach array. Firstly, the operation principle of the outer-rotor BPMSM is described. Then, the structure and performance of the Halbach permanent magnet (PM) array are analyzed. The airgap magnetic field, back-EMF, suspension force, unilateral magnetic pull force and electromagnetic torque are calculated and analyzed by the finite element analysis (FEA). Finally, it is verified that the magnetic field of the suspension force windings increases the rotor eddy current loss by transient FEA coupled with external circuit. The rotor eddy current losses of BPMSM with different structures are compared. The comparison results show that the rotor eddy current loss of the coreless-stator-type BPMSM with Halbach array is the lowest. The simulation results verify the theoretical analysis and structure design, which can provide reference for the application of the motor in the FESS.

RETRACTED: Electromagnetic performance analysis of the novel dual-mechanical-port electrical machine with Halbach permanent magnet array

“…This highly radially integrated structure inevitably has a cross-linking of the internal and external magnetic fields. To avoid the magnetic field coupling, the Halbach array [8][9][10][11] was introduced for the outer rotor permanent magnet arrangement. The Halbach array has the magnetic self-shielding property.…”

Pyrolysis-Bridged Hybrid Power Systems and Their Application for Thermal Power Plants

“…The specific chemical exergy of the coal is calculated as follows: LHV is the lower heating value of coal, and C, H, O, N represent the mass fraction of the carbon, hydrogen, oxygen, and nitrogen on a dry basis.…”

Mechanical design of flywheels for energy storage: A review with state-of-the-art developments

“…This coincides with the overspeed velocity, ! o , of a pierced disc mounted with interference i over a solid shaft of radius a, given by equation (8). Combining equations (8) and (30) gives…”

“…3 Recent developments in materials, magnetic bearings, microcomputers, and power electronics have made it possible to consider flywheels as competitive option for electric energy storage. [4][5][6][7][8][9][10][11] Other modern applications of flywheels span a wide range as uninterruptible power supply systems at several industries worldwide and kinetic energy recovery systems in electric or hybrid vehicles. 12 There are many advantages that make flywheels attractive for applications where other storing units are now used (typically electrochemical batteries and supercapacitors): (a) fast charge/discharge transients; (b) high energy density; (c) no capacity degradation with use; (d) easily measured state of charge; (e) low periodic maintenance; (f) short recharge time; (g) scalable technology and universal localization; (h) tolerance to temperature extremes; (i) low environmental impact.…”