Research On The Bi-directional Nonlinear Piezoelectric Energy Harvesting System Scavenging Energy From Mechanical Vibration

The rapid development of IOT(Internet Of Things), WSN(Wireless Sensor Networks) and low-power portable electronic devices have made piezoelectric energy harvesting from mechanical vibration be a new way of electric supply to attract researcher’s attention.The research on the new technology has gradually been a newly important research field.Based on the cantilever piezoelectric energy harvester, by the comparative study of unidirectional nonlinear piezoelectric energy harvesting system scavenging energy from mechanical vibration and unidirectional linear piezoelectric energy harvesting system scavenging energy from mechanical vibration, this dissertation finds that the unidirectional nonlinear piezoelectric energy harvesting system has broader effective bandwidth and higher output voltage. The vibration may come from various directions in practical applications. It is a strong limitation in energy harvesting efficiency. Aiming at this problem, a novel bi-directional nonlinear piezoelectric energy harvester scavenging energy from mechanical vibration is proposed in this dissertation. The theoretical model of bi-directional nonlinear piezoelectric energy harvesting system scavenging energy from mechanical vibration is presented, and by the theoretical research, the outer-beam’s and inner-beam’s open-circuit voltages and the charging voltages on energy-storage capacitor are separately researched at different frequencies and the vibration direction is separately fixed at 0°,45° and 90°. The result shows that the novel bi-directional nonlinear piezoelectric energy harvesting system scavenging energy from mechanical vibration not only has broader effective bandwidth, and when vibration direction changes it also has higher output voltage.About energy harvesting interface circuit, series-SSHI interface circuit is analyzed, and parallel-SSHI interface circuit is got in the dissertation. By the theoretical and experimental researches on those two kinds of SSHI, the dissertation finds that the voltage of energy-storage capacitor of series-SSHI interface circuit impacts on charge harvesting efficiency. To address this problem, an improved series-SSHI interface circuit is proposed in the dissertation. By the comparative study, this dissertation finds that the improved series-SSHI interface circuit has a great progress in the aspect of charge harvesting.