Simulation results of a hexahedron-octahedron based spherical stepping motor

The simulation results of a novel stepping motor based on a pair of a regular hexahedron and a regular octahedron (call "6-8 spherical stepping motor" afterward) are presented. The 3D electromagnet and motion coupled simulation program "Magnet 6" is used for the simulation. As the conditions of simulation, the excitation current and frequency is 1 A and 5.3 Hz, respectively. Three phase sinusoidal excitation currents are applied to two pairs of three coils of the stator individually at 120 deg intervals. The simulation results show that the rotor rotates along the rotating magnetic field and the output torque is 0.04 Nm. The simulation results prove the correctness of the 68 spherical motor driving method. The developed 6-8 spherical stepping motor is air-core type without back yoke for avoiding the cogging torque. When using iron core with back yoke, the proposed motor will be a high-torque spherical motor. The 6-8 spherical stepping motor was tested and the experimental results were compared with the simulation results. Then, the simulation program was used for optimum design of the 6-8 spherical stepping motor.