Design of a Coaxially Magnetic-Geared Linear Actuator for Electric Power Steering System Applications

This paper will present the designs and feasibility assessments of a linear electromagnetic actuator that can directly provide the electric power steering (EPS) forces for an economy sized vehicle. Within the physical and operational constraints, a tubular device being composed by a linear permanent magnet motor and a magnetic gears set will be systematically designed to form the coaxially magnetic-geared linear actuator. Determinations of the optimized geometrical compositions of the motor and the gears set based on the fluxes and thrust forces will be assessed in detail. For practical considerations, the dynamic performances of the proposed EPS system and the corresponding radii of turning circles will also be evaluated at various driving speeds. It is thus confirmed that the adoptions of such electromagnetic systems for those common EPS systems are technically feasible.