A Broadband Dual-Resonant Vibration Energy Harvester with Tunable Planar Spring for Overhead Transmission Lines

To address the limited output performance and low energy conversion efficiency of conventional vibration energy harvesters (VEHs) under varying ambient frequencies. A broadband dual-resonant VEH incorporating tunable planar spring mechanism is proposed for efficient energy scavenging from wind-induced vibrations of overhead transmission line. The frequency modulation mechanism of VEH adopting tunable planar spring with customized angular configuration is first analyzed. A broadband VEH with dual-resonant technique is then developed, and its frequency band broadening mechanism is systematically investigated. A prototype with two sets of planar spring angles of α = 30°/70°, β = 30°/70°, and γ = 30°/70°, and the thickness of h = 0.6/0.7 mm are subsequently fabricated and experimentally validated for the vibration energy harvesting applications in overhead transmission line. The experimental results demonstrate that the proposed VEH achieves optimal output performance at 29 Hz and 48 Hz within the frequency band range of 26-53 Hz where the output power exceeds 50% of peak, covering the vertical vibrations of 110kV transmission lines within the typical frequency range of 5-50 Hz induced by the Karman vortex effect, yielding an open-circuit peak-to-peak voltage of 9.3 V and two peak powers of 81.3 mW and 84.5 mW at the two resonant frequencies of 29 Hz and 48 Hz, with a total power density of 1.29 mW·cm−3·g−2 under external excitation vibration maintained at 100 μm and a fixed load of 2000 Ω.