Magnetic Motor Nonlinearity Modifications for Total Harmonic Distortion Improvement of an Elliptical Miniature Loudspeaker

摘要

This study reports an effort to reduce total harmonic distortion (THD) for a miniature loudspeaker by magnetic motor modifications including under yoke, polar piece, and magnet. It leads to the variation in force factor $Bl(x)$. The micro-tensile test and finite element method is employed to get $Bl(x)$ vs voice-coil displacement $x$ curves. Finite element simulation is further utilized to modify motor thence force factor curves. The manufactured prototypes of the miniature loudspeaker based on finite element simulation are further analyzed for sound pressure level (SPL) and THD. Additionally, an analytical model is also developed for getting THD. It is concluded that motor modification is a promising alternative for THD reduction.