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

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 µH'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 mm 2 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 (V OC,P ), respectively. A maximum voltage flipping efficiency of 93% is observed at V OC,P = 3.6 V, owing to minimized losses on charge flipping path. Measured results are compared with stateof-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.INDEX TERMS Autonomous, low-profile, piezoelectric energy harvester, SSHI, optimal charge flipping, area efficient, IC.

Voltage Flip Efficiency Enhancement for Piezo Energy Harvesting

“…Synchronized Switch Harvesting architectures reuse the own charge of C peh to invert the polarity of V peh upon I peh zerocrossing. They employ either an inductor (SSHI) (Sanchez et al [4], Du et al [16], Ramadass and Chandrakasan [17], Wu et al [18], Chamanian et al [19,20]) or a set of capacitors (SSHC) ( Chen et al [2], Du and Seshia [3], Chen et al [21], Hong et al [22]) to store the charge of C peh temporarily before sending it back once the electrodes of the PT have been swapped. Architectures combining both an inductor and a capacitor have also been reported in Çiftci et al [23] and Çiftci et al [1].…”

Analysis of the Methods for Realization of Low-Power Piezoelectric Energy Harvesting Circuits for Wearable Battery-Free Power Supply Devices

“…There are fewer electronic circuits implemented with discrete elements since for them, in most cases, the power dissipation is obtained with a comparatively larger value, and a smaller value for the energy efficiency is obtained. However, in all cases, the maximum overall electrical energy efficiency ranges from 50% to 80% and only in some cases exceeds 85% [8,[81][82][83][84][85]. One of the main trends in the construction of lowpower electronic converters is increasing the output power (>1 mW and mainly providing a larger output current) and simultaneously reducing the power dissipation (≤10 µW).…”

“…One of the main trends in the construction of lowpower electronic converters is increasing the output power (>1 mW and mainly providing a larger output current) and simultaneously reducing the power dissipation (≤10 µW). As can be seen in Tables 1 and 2, a higher value for electrical energy efficiency can be achieved by designing the electronic circuits basically using circuit variants of synchronized switch harvesting on inductor (SSHI) [8,[81][82][83][86][87][88][89][90][91][92][93][94], voltage rectifiers employing MOS transistors [53,81,85,87,94] or voltage multipliers with Schottky diodes [7,[59][60][61]84,86], active diodes [82,87,91,93], cold-start-up circuits [8,11,83,89], active and sleep mode of operation [8,81], self-powered circuits from the signal source, and providing a buck/boost DC-DC converter mode of operation [92], as well as a charging control circuit for an energy storage element. An interesting implementation of an electronic circuit for a cold start, which can determine an increase in energy efficiency, is given in [55].…”

A Self-Supplied Power Optimizer for Piezoelectric Energy Harvesters Operating under Non-Sinusoidal Vibrations

“…γ DBR is the percentage gain of net power at the RPVEH terminals, and it is given by Equation ( 21). Publication 2021 [32] 2022 [33] 2021 [34] 2022 [35] 2023 [36] 2021 [37] 2022 [38] This Work Type of Circuit IM (2) SSHI (3) and IM SSHI and MPPT (4) Rectifier-less SSHI SSHI SSHI SECE (7) EHPO (switchmode converter for negative capacitance emulation) Self-supplied Yes Yes Yes Yes (6) Yes Yes Yes Yes Type of prototype The experimental results, which have been shown in this section, confirm the ability of the EHPO to significantly increase the power extracted from an RPVEH. It is possible to highlight that the EHPO can operate both in the case of sinusoidal and non-sinusoidal vibrations, regardless of the shape of the input acceleration and the RPVEH resonance frequency.…”