A More Efficient Driving Method for a Spherical Superconducting Rotor

A spherical superconducting rotor is spinning at low temperature of 4.2 K. The electromagnetic field generated by the stator coils engenders driving torque on the superconducting rotor through the window on the window side wall. The driving torque at different rotation position was calculated by using finite element analysis (FEA). The results show that the driving torque is changed periodically when the rotor rotates every one quarter revolution. Based on the calculation results, this paper describes an approach to design higher efficient driving method which reduces the number of the window position patterns from eight to four and adds more driving ranges to increase driving toque. As a results, the value of driving acceleration of the rotor using this improved driving method is increased 4.58% compared with the original method with the driving current of 50 A. The rotation experiment is performed. It will be helpful to improve the acceleration efficiency of the spherical superconducting rotor.