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A Magnet-Coupled Piezoelectric Vibration Energy Harvester

To improve energy harvesting performance, a magnet-coupled piezoelectric vibration energy harvester (MCPEH) for low-level and low-frequency vibration was presented and investigated experimentally. The MCPEH consisted mainly of a piezo-cantilever with a permanent magnet at its free-end and another excitation magnet fixed on vibration structure. The magnets are used to produce magnetic attractive force to enhance energy generation. A MCPEH was fabricated with a piezo-cantilever measured 60x10x0.5mm3 and two magnets sized ø12x3mm3. The testing results show that the magnetic force, denoted by the initial separated distance between the magnetic dipoles (SDMD), exerts great influence on all of the generated voltage, optimal frequency, and effective bandwidth. With the SDMD reducing from 40mm to 15mm, the optimal frequency decrease from 32.75Hz to 30.5Hz, the effective bandwidth for the MCPEH to generated voltage of 15V rises from 2.5Hz to 7.5Hz, and the generated voltage rises from 30.4V to 44.4V.