A Self-Powered and Area Efficient SSHI Rectifier for Piezoelectric Harvesters

Salar Chamanian,Berkay Ciftci,Haluk Kulah,Ali Muhtaroglu

doi:10.1109/access.2021.3107365

Abstract

This article presents an area efficient fully autonomous piezoelectric energy harvesting system to scavenge energy from periodic vibrations. Extraction rectifier utilized in the system is based on synchronized switch harvesting on inductor (SSHI) technique which enables system to outperform standard passive rectifiers. Compared to conventional SSHI circuits, enhanced SSHI (E-SSHI) system proposed in this paper uses a single low-profile external inductor in the range of $\mu \text{H}$ ’s to reduce overall system cost and volume, hence broadening application areas of such harvesting systems. Furthermore, E-SSHI does not include any negative voltage converter circuit and therefore, it offers area efficient AC/DC rectification. Detection of optimal voltage flipping times in E-SSHI technique is conducted autonomously without any external calibration. Energy transfer circuit provides control over how much energy is delivered from E-SSHI output to electronic load. The proposed system is fabricated in 180 nm CMOS process with 0.28 mm2 active area. It is tested using a commercial piezoelectric transducer MIDE V22BL with periodic excitation. Measured results reveal that E-SSHI circuit is capable of extracting up to 5.23 and 4.02 times more power compared with an ideal full-bridge rectifier at 0.87 V and 2.6 V piezoelectric open circuit voltage amplitudes (VOC, P), respectively. A maximum voltage flipping efficiency of 93% is observed at VOC,P = 3.6 V, owing to minimized losses on charge flipping path. Measured results are compared with state-of-the-art interface circuits. Comparison shows that E-SSHI design offers a huge step towards miniaturized harvesting systems thanks to its low-profile and fully autonomous design.

Highlights

Downsizing in state-of-the-art and efficient wireless sensor networks (WSNs) makes them alluring for biomedical devices and many other applications where system size is a big concern [1]
A conventional piezoelectric harvester V22BL from MIDE company with 4.66 nF inherent capacitance (CPZ ) has been set onto a shaker table. This harvester included two electrically detached piezoelectric layers which were connected in series to enhance piezoelectric energy harvesters (PEHs) voltage output during the experiments
PEH was excited periodically at 208 Hz resonance frequency in the vibration setup, which comprised of a test PCB, a shaker table, an amplifier, a controller, vibration software, and an oscilloscope

Summary

Introduction

Downsizing in state-of-the-art and efficient wireless sensor networks (WSNs) makes them alluring for biomedical devices and many other applications where system size is a big concern [1]. Batteries that enlarges system volume and restricts their application areas. Batteries require continuous charging to keep electronic circuits inside WSN systems up and running for a long time. These bulky batteries with limited capacity can be removed from the system by making use of energy scavenging (i.e. energy harvesting) to power up electronic loads [1], [2]. Medical devices (health monitoring sensors, implantable pacemakers etc.), active RFID tags, and predictive maintenance could be counted as application areas for energy harvesting practices [1].

Objectives

Results

Conclusion