Optimization Design of a Vibration-Powered Generator With Annular Permanent Magnetic Spring and Soft Magnetic Pole

This paper presents a new electromagnetic vibration-powered generator. In the generator, the moving mass has a sandwich structure, consisting of two axially magnetized annular permanent magnets and one soft magnetic "pole piece." The purpose of using the soft magnetic pole is to increase the effective flux linkage of the generator and to increase the output voltage of the generator. The generator makes use of a "magnetic spring," which gives advantages such as ease of construction, ease of tenability, and less prone to fatigue as opposed to a mechanical spring. The mathematical model of the generator was built. The magnetic field distribution of the designed generator was analyzed by means of finite-element method. The prototype generator was built and tested with a force control electromagnetic shaker. Tests results of output waveforms have shown good agreement with simulation results. The open circuit RMS voltage of the presented generator is 662.0 mV, which increases by an additional 13.5% the one of conventional structure, at a resonance frequency of 15 Hz and an amplitude of 3 mm.