A Vibration-Based Hybrid Energy Harvester for Wireless Sensor Systems

Vibration energy harvesting has been receiving a considerable amount of interest as a means of powering wireless sensors and low power devices. In this paper, a novel hybrid energy harvester integrated with piezoelectric and electromagnetic energy harvesting technique is investigated. It consists of a cantilever beam bonding with two piezoelectric plates for piezoelectric energy conversion, and a permanent magnet attached on the end of the beam as a tip mass for inspiring the vibration and adjusting the resonance frequency, at the same time relative motion of the magnet with a conductor coil induces an electromotive force in the coil. An analytical model is developed to analyze the nonlinear vibration and electrical output performances of the harvester. A prototype is fabricated and tested. The experimental results show close agreement with the analytical results in trend. The maximum of load power of the hybrid harvester achieves 10.7 mW on the optimal load resistance of 50 Ω at the resonant frequency of 50 Hz with the acceleration of 0.4 g, which is increased by 81.4% compared with 5.9 mW of the single electromagnetic technique.