A high-thrust linear electric motor prototype for perspective replacement of shipboard hydraulic actuators

Many shipboard loads requiring high torques at very low speeds, like capstans, bow thrusters, rudders, stabilizing fins, etc., are presently driven by hydrostatic actuators. This paper presents an innovative inverter-fed electric linear motor prototype conceived to replace hydrostatic drives with large expected benefits in compactness, maintenance, efficiency and reliability. The linear motor prototype has been designed through special optimization algorithms based on finite element analysis to maximize the force density. The electromagnetic and mechanical structure has been also selected to achieve superior reliability by means of structural simplicity, robustness and redundancy. Along with design criteria, the paper outlines the prototype technology and the construction issues and provides some testing results collected during the experimental performance assessment.