A Self-Powered and Optimal SSHI Circuit Integrated With an Active Rectifier for Piezoelectric Energy Harvesting

• Published in: IEEE transactions on circuits and systems. I, Regular papers Regular papers, 2017-03, Vol.64 (3), p.537-549
• Main Authors: Wu, Liao, Do, Xuan-Dien, Lee, Sang-Gug, Ha, Dong Sam
• Format: Article
• Language: English
• Subjects: active rectifier; Cantilever bridges; Capacitors; Control systems design; Controllers; Electric potential; Energy conversion efficiency; Energy dissipation; Energy harvesting; Inductors; Inserts; piezoelectric energy harvesting; Piezoelectricity; Power management; Rectifiers; RLC circuits; SSHI; Switches; Switching circuits; Time synchronization; Transducers; Vibration energy harvesting; Voltage
• ISSN: 1549-8328; 1558-0806
• DOI: 10.1109/TCSI.2016.2608999

This paper presents a piezoelectric energy harvesting circuit, which integrates a Synchronized Switch Harvesting on Inductor (SSHI) circuit and an active rectifier. The major design challenge of the SSHI method is flipping the capacitor voltage at optimal times. The proposed SSHI circuit inserts an active diode on each resonant loop, which ensures flipping of the capacitor voltage at optimal times and eliminates the need to tune the switching time. The diodes of the SSHI circuit are also used as a rectifier to further simplify the controller. The key advantage of the proposed circuit is a simple controller, which leads to low power dissipation of the proposed circuit to result in high efficiency. The proposed circuit is self-powered and capable of starting even when the battery is completely drained. The circuit was fabricated in BiCMOS 0.25 μm technology with a die size of 0.98 × 0.76 mm 2 . Measured results indicate that the proposed circuit increases the amount of power harvested from a piezoelectric cantilever by 2.1 times when compared with a full bridge (FB) rectifier and achieves a power conversion efficiency of 85%. The proposed circuit dissipates about 24 μW while the controller alone only 1.5 μW.