Dynamic performance of three-DoF conical magnetic bearing in Vernier gimballing MSFW

For the 5-DoF gimballing magnetically suspended flywheel (MSFW), a three-degrees-of-freedom (DoF) active magnetic bearing (AMB) with a conical gap is used as an electromagnetic actuator to suspend the flywheel (FW) rotor, so the gyro moment of gimballing MSFW is improved by actively deflecting FW rotor with the conical AMB. Firstly, the dynamic models of the FW rotor with the 3-DoF conical AMB are investigated, and the magnetic forces using the equivalent magnetic circuit and the FEM model are analyzed. Moreover, the coupling effect among three controllable DoFs of conical AMB is investigated when the position of the FW rotor sets at different values. Furthermore, the negative torques of conical AMB are studied when the FW rotor is stably suspended at the equilibrium position. The experimental results indicate that the controllable deflection angle of 3-DoF conical AMB reaches 1°, the coupling ratio among three controllable DoFs is reduced to 9%, and the negative torque during the active deflecting process is 0.02 Nm. Compared to the normal AMB with the planar gap, the designed 3-DoF conical AMB has a wide deflection angle, minor coupling effect, and tiny negative torque. Therefore, the 3-DoF conical AMB causes slight influences on the FW rotor during the suspension and deflection control of gimballing MSFW, and it is more suitable for the gimballing MSFW.