A Low-Frequency High-Performance Harvesting System With Combined Cantilever Beam

In order to achieve highly efficient energy harvesting in low-frequency vibration environment, a combined cantilever piezoelectric energy harvester (CCPEH) is studied in this work. The design uses a circular cantilever beam to reduce the resonant frequency and achieve multi-directional energy harvesting. The trapezoidal cantilever beam and arc spiral cantilever beam are coupled to each other to improve the energy harvester efficiency per unit volume. The relationship of the arc with radial pitch of circular cantilever beam is studied. The piezoelectric energy harvesting system with different combined cantilever beam structure is fabricated, and the output performance of those energy harvesting systems are measured and compared. The measured results show that the CCPEH with an arc of 4π and a radial pitch of 8 mm can achieve multi-directional harvesting and improve the energy harvesting efficiency per unit volume with a resonant frequency of 39 Hz, an output voltage of 46.4 V, and an output power of 2337 μW. This structure of piezoelectric energy harvester can be effectively applied in wireless sensors and microelectronic devices.