flywheels, finite element analysis, AC motors, single winding bearingless flywheel motor, SWBFM, cost savings, consumption reduction, radial force, mathematical model, Maxwell tensor method, correction factor, finite element analysis, energy storage keeping state, flywheel energy storage system, radial force coefficient, radial force dynamic current compensation methods, winding open-circuit fault
The position of rotor and stator in switched reluctance motor is exchanged to obtain the single winding bearingless flywheel motor (SWBFM), which is more useful for flywheel energy storage with outer rotor. Compared with the switched reluctance motor, bearingless flywheel motor has obvious advantages in cost savings and consumption reducing. The radial force and torque are produced by single windings and the outer rotor could directly drive the flywheel with less mechanical transmission. In this study, a mathematical model of SWBFM is established based on Maxwell tensor method, in addition, the correction factor is present to obtain an accurate mathematical model based on finite element. In energy storage keeping state, the flywheel energy storage system could run on rated speed without the power input. Considering the relationship between the angle and the radial force coefficient, and the difference of radial force coefficient with each tooth pole, radial force dynamic current compensation methods of without β direction constraint and β direction constraint are present to ensure the SWBFM stable suspension under the condition of winding open-circuit fault. The results show that the proposed compensation methods are feasible and have high precision.