Voltage Flip Efficiency Optimization of SSHC Rectifiers for Piezoelectric Energy Harvesting

Abstract

Harvesting energy from environments has been a promising approach to power ubiquitously distributed Internet of Things (IoT) devices. For harvesting kinetic energy with piezoelectric transducers, synchronized switch harvesting on capacitors (SSHC) rectifiers have been demonstrated to achieve high energy extraction performance without using any inductor. In previous studies, the switched capacitors in SSHC rectifiers are chosen equal to the inherent capacitance of the piezoelectric transducer (PT) to achieve good voltage flip efficiencies at 33.3%, 50% and 66.7% for 1-, 2-and 4-stage SSHC rectifiers, respectively. However, with much larger switched capacitors and the same SMD package size, this paper finds that the voltage flip efficiency can be further increased to 50%, 66.7% and 80% for 1-, 2-and 4-stage SSHC rectifiers, respectively; as a result, the output power can be greatly increased. This paper also finds that the proposed design only requires half number of capacitors to achieve the same voltage flip efficiency for conventional SSHC rectifiers, which significantly reduces the system form factor for miniaturization.Index Terms-energy harvesting, synchronized switch harvesting on capacitors (SSHC), fully-integrated system, rectifiers

A review of nonlinear piezoelectric energy harvesting interface circuits in discrete components

“…The theoretical maximum voltage inversion efficiency in the SSHC circuit when C k = C p is shown in Table 1. Yue and Du [88] found that in the energy transfer process, when the voltage balance was reached, the remaining charge of the PZT when C k C p would be much smaller than that when C k = C p . When C k = 100C p , the relationship between the voltage inversion efficiency and the number of C k is shown in Table 2.…”

“…The voltage drop of the diode on circuit conduction can be reduced under low output voltage conditions Inductorless interface circuit [86][87][88] -Bad × Small size, large number of capacitors, and troublesome switching control strategy continued Circuit Maximum output power Load adaptability Selfpowered Features SCEVI [89] 1.5/SECE Good ×…”

A Review of Converter Circuits for Ambient Micro Energy Harvesting

“…Capacitor-based circuits applied to piezoelectric energy harvesting include the synchronized switch harvesting on capacitor (SSHC) [57], the flipping-capacitor rectifier (FCR) [58], and the split-phase flipping-capacitor rectifier (SPFCR) [59], which allow on-chip integration by avoiding the use of off-chip inductors.…”

A Synchronized Switch Harvesting Rectifier With Reusable Storage Capacitors for Piezoelectric Energy Harvesting

“…E NERGY harvesting has emerged as an alternative solution to traditional batteries, which are often bulky and difficult to replace in wireless applications in the Internet-of-Things (IoT) [1], [2], [3], [4], [5]. Among energy-harvesting systems, piezoelectric energy harvesting (PEH) has been widely used in recent years due to its high power density and compatibility with CMOS technologies [1], [6], [7], [8], [9], [10]. It harvests vibration energy from environments and converts it into electrical energy with a piezoelectric transducer (PT).…”