Operation Principle of a Novel Coaxial Triple-DOF Motor

This paper proposes a novel single-stator three-rotor coaxial triple-DOF motor (TDOFM) based on the principles of electrical pole-changing (EPC) and magnetic field modulation (MFM). The proposed motor topology involves a single stator and three rotors with different pole pair numbers arranged coaxially along the axial direction. Each rotor can be controlled separately by the same set of 7-phase windings using the EPC method. Additionally, the MFM principle is utilized to enhance the pole ratio, enabling open-loop decoupling control under light load conditions. Finite element analysis (FEA) is conducted to validate the operation principles and investigate the decoupling operation characteristics. Finally, the prototype is manufactured and tested to verify the feasibility of the decoupling operation of the TDOFM.