Evaluation of the normal force of a planar actuator

This paper describes a method to compute the normal force between the mover and stator of an electromagnetic planar actuator. The method is based on the Maxwell stress tensor and depends on the resulting magnetic field. The actuator has a mover with two permanent magnets and a ferromagnetic stator covered by two orthogonal armature coils. The mover relies on a suspension system with linear bearings that enable bi-directional motion. When one permanent magnet is located over an excited coil phase, a magnetic propulsion force will act on the mover and that pushes the latter accordingly. A normal magnetic force is an intrinsic effect and determines the mechanical load the suspension system sustains. It represents an attraction force between the permanent magnets and the armature core that may affect the mechanical structure of the actuator and its movement.