Innovative Dual-Excitation Drive in Fault Tolerant Double-Stator Vernier Machines for Ship Propulsion

Electric propulsion has gained attention in the maritime industry due to its flexibility, energy efficiency, and adaptability for diverse ship types, including icebreakers, cruise ships, and research vessels. The continuous advancement of motor technologies has significantly redefined propulsion systems. Among these innovations, axial flux permanent magnet synchronous machines (AFPMSMs) stand out for their exceptional torque density, making them particularly suitable for low-speed direct-drive applications. Additionally, the high torque at low rotational speeds of the machine contributes to streamlining drivetrain complexity and reducing maintenance demands. This paper introduces a novel 1 MW AFPMSM, MAGNUS, which combines an inner spoke-rotor with dual external high-polarity stators with a minimal number of teeth, capable of operating with a single stator during faulty conditions. Performance indices for traction applications, derived from analytical torque-speed characteristics and Finite Element Analysis (FEA) calculated torque versus torque angle, demonstrate the effectiveness of the proposed machine architecture. These results indicate the machine's capability to maintain operation within the constant power region of its torque-speed profile. In faulty scenarios, its dual-stator configuration and independent drives ensure approximately 70% torque retention, supporting safe and reliable marine operation. Furthermore, the compact and thermally robust structure accommodates scalable power levels, making it a compelling solution across a wide range of vessel classes.