Abstract
An induction voice coil motor (VCM) is composed of a moving metal ring, permanent magnets, cores and exciting coils. The moving ring current induced by an exciting coil current, and the magnetic flux of permanent magnets generate a driving force in the moving ring. The induction VCM is not able to generate forces below the lower cut-off frequency and also above the higher cut-off frequency. The lower cut-off frequency is reduced by the higher permeability and the lower hysteresis loss of the core, and the higher cut-off frequency increases by the lower eddy current loss of the core and the lower leakage inductance of the moving ring. There is an electro-mechanical parallel resonance near the lower cut-off frequency, and the higher permeability and the lower loss make the resonance stronger and make the resonance frequency lower.
