서강대학교

초록/요약

This paper presents a new type of piezoelectric and electrostatic hybrid energy harvester based on rotating motion. The proposed device has complementary advantages that does not require additional power supply and impedance matching circuit. The proposed device consists of rotating piezoelectric cantilevers for piezoelectric energy harvesting and a variable capacitor for electrostatic energy harvesting. The energy harvested from the piezoelectric cantilevers is rectified and additional energy is harvested through the electrostatic energy harvesting. It is stored in a load capacitor. The operation of the proposed device was confirmed by equivalent circuit simulation and the actual device was fabricated based on the simulation. The fabricated device was made of acrylic base, and the piezoelectric cantilever was fabricated by PVDF and PET film. The dimension was 40*5*0.11 mm2. The two electrodes formed for the variable capacitor structure were fabricated by silver with a diameter of 60 mm. The open-circuit voltage and short-circuit current measured in the piezoelectric cantilevers of the fabricated device were measured to be 8.5 Vrms and 0.62 μA at maximum. Compared with single energy harvesting using the piezoelectric cantilever, the fabricated device exhibits difference of approximately 96 % of the maximum voltage stored in the load capacitor for the same time, 51 V and 26 V, respectively. This is the result of energy harvesting efficiency improved by combining two energy harvesting methods.