A high absolute thrust permanent magnet linear actuator for direct drive of ship's steering gears: Concept and FEM analysis

“All-electric-ships” are under development all over the world. Aside of electric propulsion and electric power system issues, other challenges concern the innovation of oil-powered on-board actuators. Very high torques/forces and operating affordability are required in rudder and fin drives. This paper proposes a concept of permanent magnet linear synchronous actuator (PMLSA) for direct rudder and fin actuation, without any mechanical reduction. Linear motion is reverted to rotary motion through a rotary-prismatic coupling. Main features of the PMLSA are: 1) very large direct thrust in 2) limited weight and 3) limited space, with 4) good efficiencies in 5) low speed operation. This paper shows concept, mechanical and electro-magnetic design and sizing, and FEM simulations of the proposed innovative actuator. A companion paper shows the electrical design and analyzes efficiencies and dynamic inverter control.