A Dual-resonance Electromagnetic Vibration Energy Harvester for Wide Harvested Frequency Range

A dual-resonance vibration electromagnetic energy harvester is proposed in this paper to extend frequency range of available output voltage and power. A serpentine planar spring is employed and the coil position is optimized for higher normalized power density. Compared with single-resonance harvester and state-of-art, the proposed system has excellent performance when excitation frequency is between of two resonant frequencies. A $\Phi 31.2$ mm $\times 70.5$ mm dual-resonance EMEH is designed with output power reaching 11 mW at 58 Hz and 14.9 mW at 74.5 Hz. The max. normalized power density is 2.77 mW/(cm$^{3}\cdot \mathrm{g}^{2})$. The frequency range of output power above 0.5 mW is from 55.8 Hz to 79.1 Hz. Compared with single-resonance harvester with resonant frequency 74.5 Hz, the frequency range is from 70.1 Hz to 80.1 Hz. The frequency range in the dual-resonance harvester is more than twice of that in single-resonance harvester. At a load of $300 \Omega$, the frequency range of NPD above 0.8 mW/(cm$^{3}\cdot \mathrm{g}^{2})$ is from 55 Hz to 78 Hz, reaching frequency width of 23 Hz. This range is far beyond that in other literature. The proposed EMEH is verified with a very wide harvested frequency range and rather high max. NPD.