Experimental research on nonlinear coupling between two sides of rectification in piezoelectric energy harvester

This paper proposes a piezoelectric energy harvester experiment model, which composed of piezoelectric harvesting element, energy storage element, and a full bridge to connect them as an integrated system. A synchronized switch harvesting inductor (SSHI) is introduced in parallel with the harvesting structure to reverse voltage through the charge transfer between the output electrodes at the transition moments from closed- to open- circuit, i.e. the time when the harvesting structure deforms to the extreme position. The harvesting structure is driven to vibrate by vibration exciter which is acted by a voltage signal with a certain frequency. The method of capturing zero velocity is used to catch the moment when the harvesting structure deforms to the extreme position. SSHI closes synchronously, and delay a half period of the oscillator, composed by the inductor and effective capacitor of piezoelectric harvesting structure, then opens. This process is controlled by the technique of single chip microcomputer. Experimental results show SSHI processes have been achieved. An optimal rectified voltage can maximize the output power density of the piezoelectric energy harvester.