Design and optimization of a compact broadband piezoelectric energy harvester system with enhanced efficiency

This paper presents a high-performance piezoelectric energy harvesting system with a compact design for broadband vibration. The presented piezoelectric energy harvesting system converts vibration energy into electrical power for low-power electronics, offering an alternative to conventional power sources. First, we introduce a 43 mm × 20 mm × 30.1 mm compact broadband piezoelectric energy harvester (CBPEH) with two closely spaced bending vibration resonant frequencies at 48 Hz and 62 Hz, covering the critical 50 Hz, resulting in a broad operational bandwidth from 35 Hz to 90 Hz. To the best of our knowledge, considering the size of piezoelectric energy harvesters (PEHs), this is the highest achieved bandwidth among the published PEHs. Second, to improve energy conversion efficiency, we propose an extensible self-powered dual-capacitor switch-synchronous electric charge extraction (SDCS-SECE) interface circuit. This circuit effectively manages varying phase relationships in PEHs, preventing energy backflow and ensuring that the different PEHs operate without interference. Experimental results demonstrate optimal system performance within the 35–90 Hz range, achieving a normalized power density of up to 0.995 μW/(mm3⋅g). Moreover, the proposed CBPEH system successfully powers a wireless accelerometer, showing its potential as an independent power supply for wireless sensor networks.