무선 통신을 위한 압전과 전자기유도방식 발전의 하이브리드 에너지 하베스팅 시스템

Abstract

In this study, a hybrid energy harvesting system for wireless communication was designed. The hybrid energy harvester was composed of a piezoelectric and an electromagnetic energy harvester. A piezoelectric energy harvester generated higher voltage than an electromagnetic energy harvester and an electromagnetic energy harvester generated more current than a piezoelectric energy harvester, so two energy harvesters were combined to utilize the advantages of each harvester. Also, the capacitive property in a piezoelectric energy harvester was compensated by the inductive impedance of an electromagnetic energy harvester. Both piezoelectric and electromagnetic energy harvesters had been applied to a sustain pedal of the piano. A sustain pedal was chosen as the application of an energy harvester because of its steady input energy with higher energy density. The experiments were performed on a piezoelectric and an electromagnetic energy harvester respectively to optimize the energy harvesting systems. The piezoelectric energy harvester was tested on the various spacers, which allowed more deformation to the piezoelectric material. The piezoelectric energy harvester was simulated by using ANSYS and found that a 0.7-mm thickness spacer was the optimum condition. The electromagnetic energy harvester was wound 2,500 times by the 0.10-mm-diameter enameled copper wire and operated with a neodymium permanent magnet. After the impedances of the two harvesters were measured by an impedance analyzer, the complex impedance of the hybrid energy harvester was calculated. The sustain pedal was pressed 5 times during 10 seconds. While the generated power of the piezoelectric and electromagnetic energy harvesters were 24.0 and 155 µW respectively, the hybrid energy harvester produced 244-µW energy. The generated energy from the hybrid energy harvester was higher than the stand-alone piezoelectric or electromagnetic energy harvester. The reason was that the complex impedance of the hybrid energy harvester was reduced due to the compensation effect of two energy harvesters. Finally, a signal was sent with infrared communication system and it was successful in transmitting signals within one meter distance by using the hybrid energy harvester. This study achieved wireless communication by using energy harvesting system and discovered the lead-lag compensation of the hybrid energy harvesting system, thereby reducing the reactive power.