マグネットレスボイスコイルモータとその駆動特性 [in Japanese] Magnetless Voice Coil Motor and the Driving Characteristics [in Japanese]
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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 J<sub>2</sub> and a gap flux density B<sub>G</sub>, which are induced by an exciting current J<sub>1</sub>, and a reluctance force due to J<sub>2</sub>. The driving force F is proportional to J<sub>1</sub><sup>2</sup>/g, where g is a gap length, and almost independent of mover position under a constant J<sub>1</sub> and above a lower cutoff angular velocity ω<sub>J1</sub>, of an induced current. ω<sub>J1</sub> 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 J<sub>2</sub> and a gap flux density B<sub>G</sub>, 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 J<sub>1</sub>.
- IEEJ Transactions on Sensors and Micromachines
IEEJ Transactions on Sensors and Micromachines 115(3), 198-203, 1995-03
The Institute of Electrical Engineers of Japan