マグネットレスボイスコイルモータとその駆動特性

抄録

A magnetless voice coil motor (MLVCM) is generally composed of a closed magnetic circuit stator core (laminated electical steels), two exciting coils on the core and a metal ring mover, without pernament magnets and leading wires connected with the mover. A driving force F is both an electromagnetic force between a mover current J₂ and a gap flux density B_G, which are induced by an exciting current J₁, and a reluctance force due to J₂. The driving force F is proportional to J₁²/g, where g is a gap length, and almost independent of mover position under a constant J₁ and above a lower cutoff angular velocity ω_J1, of an induced current. ω_J1 becomes lower with the lower electric resistance of a mover and the lower reluctance of a magnetic circuit (stator core), and consequently a MLVCM with a closed magnetic circuit generates a higher driving force than that with an open magnetic circuit. The higher permeability and the lower iron loss of a magnetic circuit core increase a mover current J₂ and a gap flux density B_G, and then a driving force becomes greater. A voltage applied to the exciting coil increases proportionally to the distance between an exciting coil and a mover under a constant J₁.