Energy Harvesting Interface Circuit Research Articles

A Self-Bias-Flip With Charge Recycle Interface Circuit With No External Energy Reservoir for Piezoelectric Energy Harvesting Array

This paper presents a piezoelectric energy harvesting (PEH) interface circuit using a new self-bias-flip with charge recycle (SBFR) technique without employing any additional energy reservoir. Traditional designs, including synchronous-switch harvesting on inductor (SSHI), synchronous-switch harvesting on capacitor (SSHC), synchronous electric charge extraction (SECE), etc., require additional capacitors or inductors to reverse the voltage on the PEH at the zero-crossing point. This design innovatively uses the inherent capacitors of the piezoelectric harvesters as the flipping capacitors. In order to improve the extract efficiency of the interface, the zero-crossing state is split into charge recycle stage and voltage-flip stage. For a piezoelectric array with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2^{n}$</tex-math></inline-formula> PEHs, a configuration with (n-1) phases in the charge recycle stage is adopted to reduce the loss caused by direct charge neutralization. The charge redistribution loss is reduced by employing (2n+1) phases in the voltage-flip stage. The proposed principle has been implemented with discrete components and is verified by 3 different prototypes. The measurement results show that a flipping efficiency of 67% is achieved by utilizing SBFR with 4 PEHs. And the proposed interface can provide up to 5.2x improvement when compared with the full-bridge rectifier (FBR).

A Fully Autonomous SSHIC Interface Circuit With Configurable Multi-Step Bias-Flip for Piezoelectric Energy Harvesting

This brief presents a piezoelectric energy harvesting interface circuit with a multi-step bias-flip strategy to boost the energy extraction capability. The optimized parallel synchronized switch on inductor and capacitor (SSHIC) technique is adopted. Except for the external inductor and capacitors, the proposed interface circuit is designed for fully integrated control without any external adjustment during the bias-flip process. Moreover, the steps for bias-flip can be configured flexibly, and the circuit can work even without an inductor. The interface circuit has been designed and implemented with 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu }\text{m}$ </tex-math></inline-formula> CMOS technology. With the 5-step bias-flip SSHIC topology and a 1-mH inductor, the simulated whole current dissipation is 106 nA, the measured maximum flipping efficiency is 90.3%, and the measured maximum power efficiency improvement is 642% compared to the ideal full bridge rectifier (FBR).

A Highly Adaptive and Flipping-Time Optimized Piezoelectric Energy Harvesting Interface IC With Synchronized Triple Bias-Flip

This article presents a piezoelectric energy harvesting interface circuit with high adaptability to external inductors, transducer types, and vibration frequencies. High output power can be obtained with the help of triple bias-flip and optimal flipping time control. The triple bias-flip enables both higher efficiency and the use of an inductor with lower volume compared to conventional bias-flip topologies. Besides, owing to the highly adaptive circuit design and reverse current reduction in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant loop, the proposed interface circuit not only automatically adjusts flipping time according to external inductance and piezoelectric transducer, but also reduces the reverse current of the inductor effectively. Also, an active rectifier that can reduce conduction loss of the diode-based rectifier has been implemented. The prototype integrated circuit has been fabricated in 180-nm CMOS technology and the chip area is 0.646 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The measurement results show that the proposed circuit achieves cold start-up without any external power supply, and can work with high efficiency when the external inductor is varying from 0 to 10 mH, transducer capacitance is changing from 20 to 90 nF, and vibration frequency is ranging from 35 to 200 Hz. The measured maximum output power of the proposed design can achieve as high as 473% enhancement to the full-bridge rectifier.

Efficient self-powered piezoelectric energy harvesting interface circuit with wide rectified voltage

Synchronized Switching Harvesting on Inductor (SSHI) and Synchronous Electric Charge Extraction (SECE) are two classic interface circuit techniques for Piezoelectric energy harvesting. But the former has high peak output power with narrow rectified voltage range, while the latter has wide rectified voltage range with lower peak output power. This paper presents a self-powered interface circuit for piezoelectric energy harvesting to achieve a good balance between the two. The proposed interface circuit is based on the Series-SSHI (S–SSHI) and SECE. The circuit proposed can harvest energy through S–SSHI and SECE in positive and negative half cycles, respectively. Moreover, the figure of merit (FOM), optimal rectified voltage range (ORVR) and region of interest (SRoI) of simulation and experiment results are discussed. The maximum FOM of the proposed circuit is as high as 2.15, which is 1.68 times that of the SECE, and it can reach 6 times the ORVR of the S–SSHI. SRoI factor of the proposed circuit show that the proposed method has better performance. In addition, the circuit shows a simpler implementation compared with state-of-the-art designs.

Design of an Energy Harvesting Interface Circuit Consecutively Powering Two Loads

ABSTRACT This paper presents an energy harvesting interface circuit for a single ambient energy source that consecutively delivers power supply to two loads including one light load and one heavy load. The proposed circuit consists of a step-up converter, a temporary storage element (e.g. supercapacitor), two charge control circuits for the loads, and two power transistors. The converter receives low-voltage from the output of the energy source to charge the supercapacitor at the output of the converter to high voltage levels. The supercapacitor delivers energy to the light load through corresponding control circuit. Due to the light load, the generated energy by the energy source is greater than the required power by the load. This results in accumulating the surplus energy into the supercapacitor. Once the supercapacitor stores sufficient energy, the energy direction from the supercapacitor is shifted from the light load to the heavy load. Once the supercapacitor discharges to a voltage level where the heavy load stops to receive power supply, the energy direction will be toward to the light load again. The same powering pattern will be repeated over the time. As a result, these loads operate in burst mode. The proposed circuit, constructed with off-the-shelf components, regulates outputs to nearly 3.9 V, starts the operation from an input voltage as low as 0.1 V and achieves a peak efficiency of 73.29%. The proposed circuit provides the highest output power of 124.14 mW which is greater than prior IC work supports. Apart from the highest output power, the proposed circuit meets the goal of self-sustainability since there is no need of extra power source (e.g., battery) other than the ambient energy source.

Lumped Parameter Evaluation Model Analysis and Load Coupling Modeling of Piezoelectric Composite Cantilever Beam

In order to study the working mechanism of piezoelectric composite cantilever beam and improve the ability of predicting the power generation performance of piezoelectric composite cantilever vibration energy harvester (CVEH), the simple and high-precision analysis models of equivalent mass and equivalent stiffness of CVEH are proposed. The natural frequency method is used to compare the calculation results of the evaluation model, Rayleigh Ritz method and finite element simulation, and the results show that the consistency (Ω) between the evaluation model and the finite element simulation is more than 95%. The influence of the mass ratio (α) between the end mass of the beam and the weight of the beam itself on Ω is analyzed by using the proposed evaluation model, which shows that Ω increases with the increase of α, and the increase is more significant in the range of 0<α<4. The analysis of the influence of α on the natural frequency of the beam () shows that decreases with the increase of α, and the decrease is more obvious in the range of 0<α<2. According to the evaluation model, the electromechanical conversion analysis models of CVEH and its control equation with coupling of standard energy harvesting (SEH) interface circuit and Double synchronous switch harvesting (DSSH) interface circuit are established respectively, and the mathematical models of its output voltage are derived. The power generation experiment of CVEH is carried out, and the results show that the proposed models are in good agreement with the experimental results.

A unified equivalent circuit and impedance analysis method for galloping piezoelectric energy harvesters

In the past decade, galloping-based energy harvesters (GPEH) connected with various interface circuits have been developed and analytical models have been built. However, the power performances of these advanced structures and circuits are always treated separately, and a general model is missing to gain insights at a system level. To tackle this issue, this paper proposes a unified analysis framework for GPEHs. Its results are consistent with validated (but disconnected) results in the literature. The method provides an integrated view of the physics of linear GPEHs in multiple domains at the system level, and elucidates the similarities and differences among power behaviors of GPEHs connected with various interface circuits. The framework is based on two major elements: an equivalent circuit that represents the entire system, and an equivalent impedance that represents the interface circuit. Firstly, the electromechanical system is linearized and modeled in the electrical domain by an equivalent self-excited circuit with a negative resistive element representing the external aerodynamic excitation, and a general load impedance representing the interface circuit. Then, a closed-form, analytical expression of the harvested power is obtained based on the Kirchhoff’s Voltage Law, from which the optimal load, maximum power, power limit, and critical electromechanical coupling (minimum coupling to reach the power limit) are determined. In this unified analysis, the exact type of energy harvesting interface circuit is not assumed. After that, the power characteristics of a GPEH connected with five representative interface circuits are analytically derived and discussed, by using the particular equivalent impedance of the interface circuit of interest. It is shown that they are subjected to the same power limit. However, the critical electromechanical coupling depends on the type of circuit. Throughout the discussions, impedance plots are used to illustrate the relationship between the internal system characteristics and external load impedance, facilitating the understanding of system power behavior.

Thermoelectric Energy Harvesting Interface Circuit With Capacitive Bootstrapping Technique for Energy-Efficient IoT Devices

This paper presents a low-input-voltage (100 mV), low-output-voltage (500–600 mV) thermoelectric energy harvesting interface circuit for near-threshold energy-efficient Internet-of-Things (IoT) devices. The capacitive bootstrapping technique is used to generate a positive and negative bias pair for alleviating the significant conduction losses of power MOSFETs in a near-threshold operation. Internal bias voltages are automatically boosted to different levels as per the loading conditions to extend the output power range. The deployment of constant on-time digital pulse skip modulation with digital zero current detection (ZCD) achieves an ultralight load operation, and precluding a reverse current. The digital ZCD is capable of dynamically adjusting the off-time ( ${T}_{\mathrm {OFF}}$ ) of the power transistors, which vary according to the input and output voltage levels. The proposed step-up dc-dc power converter implemented using a 180 nm CMOS technology demonstrates a maximum conversion efficiency of 76.4% over a $1~{\mu }\text{W}$ – $500~{\mu }\text{W}$ load range, significantly evaluating the feasibility of the near-threshold interface circuit architecture for energy-efficient IoT devices.

A self-powered piezoelectric energy harvesting interface circuit with efficiency-enhanced P-SSHI rectifier * * Project supported by the National Natural Science Foundation of China (Nos. 61574103, U1709218) and the Key Research and Development Program of Shaanxi Province (No. 2017ZDXM-GY-006).

The key to self-powered technique is initiative to harvest energy from the surrounding environment. Harvesting energy from an ambient vibration source utilizing piezoelectrics emerged as a popular method. Efficient interface circuits become the main limitations of existing energy harvesting techniques. In this paper, an interface circuit for piezoelectric energy harvesting is presented. An active full bridge rectifier is adopted to improve the power efficiency by reducing the conduction loss on the rectifying path. A parallel synchronized switch harvesting on inductor (P-SSHI) technique is used to improve the power extraction capability from piezoelectric harvester, thereby trying to reach the theoretical maximum output power. An intermittent power management unit (IPMU) and an output capacitor-less low drop regulator (LDO) are also introduced. Active diodes (AD) instead of traditional passive ones are used to reduce the voltage loss over the rectifier, which results in a good power efficiency. The IPMU with hysteresis comparator ensures the interface circuit has a large transient output power by limiting the output voltage ranges from 2.2 to 2 V. The design is fabricated in a SMIC 0.18 μm CMOS technology. Simulation results show that the flipping efficiency of the P-SSHI circuit is over 80% with an off-chip inductor value of 820 μH. The output power the proposed rectifier can obtain is 44.4 μW, which is 6.7× improvement compared to the maximum output power of a traditional rectifier. Both the active diodes and the P-SSHI help to improve the output power of the proposed rectifier. LDO outputs a voltage of 1.8 V with the maximum 90% power efficiency. The proposed P-SSHI rectifier interface circuit can be self-powered without the need for additional power supply.

Vibration Based Energy Harvesting Interface Circuit using Diode-Capacitor Topologies for Low Power Applications

&lt;span&gt;A battery-less energy harvesting interface circuit to extract electrical energy from vibration has been proposed in this paper for low power applications. The voltage doubler integrated with DC – DC boost converter circuits were designed and simulated using MultiSIM software. The circuit was then fabricated onto a printed circuit board (PCB), using standard fabrication process. The Cockcroft Walton doubler was chosen to be implemented in this study by utilizing diode-capacitor topologies with additional RC low pass filter. The DC – DC boost converter has been designed using a CMOS step -up DC – DC switching regulators, which are suitable for low input voltage system. The achievement of this interface circuit was able to boost up the maximum voltage of 5 V for input voltage of 800 mV.&lt;/span&gt;

A Self-Powered Piezoelectric Energy Harvesting Interface with Wide Input Range in 65 nm CMOS Process

ABSTRACTA self-powered piezoelectric energy harvesting interface circuit (PEHIC) with wide input range and good performance is presented in this paper. The proposed PEHIC consists of a two-stage active charge pump rectifier and an ultra-low power intermittent power management unit (IPMU). Active diodes based on unbalanced-biased comparators improve the reverse leakage current problem that conventional active diodes faced. By limiting the output voltage between 1.2 and 0.8 V, the IPMU working in intermittent mode can provide an expanded input range and ensure that the interface circuit has a large transient output power. Implemented in a 65 nm standard complementary metal oxide semiconductor (CMOS) technology, the PEHIC has been simulated and verified. Simulation results show that an AC signal with amplitude ranging from 0.32 to 1.5 V and frequencies of 20 Hz–3 kHz can be rectified. The maximum output current is as large as 5 mA. The peak power conversion efficiency is up to 81% when the input voltage is 0.8 V at 200 Hz. The PEHIC can be self-powered without the need for additional power supply.

Performance Evaluation a Developed Energy Harvesting Interface Circuit in Active Technique

Performance Evaluation a Developed Energy Harvesting Interface Circuit in Active Technique

Dielectric loss against piezoelectric power harvesting

Piezoelectricity is one of the most popular electromechanical transduction mechanisms for constructing kinetic energy harvesting systems. When a standard energy harvesting (SEH) interface circuit, i.e., bridge rectifier plus filter capacitor, is utilized for collecting piezoelectric power, the previous literature showed that the power conversion can be well predicted without much consideration for the effect of dielectric loss. Yet, as the conversion power gets higher by adopting power-boosting interface circuits, such as synchronized switch harvesting on inductor (SSHI), the neglect of dielectric loss might give rise to deviation in harvested power estimation. Given the continuous progress on power-boosting interface circuits, the role of dielectric loss in practical piezoelectric energy harvesting (PEH) systems should receive attention with better evaluation. Based on the integrated equivalent impedance network model, this fast track communication provides a comprehensive study on the susceptibility of harvested power in PEH systems under different conditions. It shows that, dielectric loss always counteracts piezoelectric power harvesting by causing charge leakage across piezoelectric capacitance. In particular, taking corresponding ideal lossless cases as references, the counteractive effect might be aggravated under one of the five conditions: larger dielectric loss tangent, lower vibration frequency, further away from resonance, weaker electromechanical coupling, or using power-boosting interface circuit. These relationships are valuable for the study of PEH systems, as they not only help explain the role of dielectric loss in piezoelectric power harvesting, but also add complementary insights for material, structure, excitation, and circuit considerations towards holistic evaluation and design for practical PEH systems.

A Batteryless low Input Voltage micro-scale Thermoelectric Based Energy Harvesting Interface Circuit with 100mV Start-up Voltage

A Batteryless low input voltage micro-scale thermo electric based energy harvesting interface circuit with 0.1V start-up voltage presents in this paper. The active technique and its components have been chosen such as MOSFET and thyristor to design the proposed DC-DC boost converter with low input voltage (i.e., 0.1V) for energy harvesting interface circuit. The minimum working voltage as low as 0.1V an input the equivalent voltage of thermoelectric transducer has been proposed to design the boost converter. This paper presents techniques for the systematic modeling, analysis, and design of interface circuitry used in the equivalent voltage of the micro-scale thermoelectric energy harvesting systems. In the development of active-based circuits, the DC-DC step-up (boost) converter with thyristor have been designed instead of mainly diode and other components because the forward voltage of diode is (0.7V) higher than the incoming input voltage (0.1V). Finally, the complete proposed energy harvester circuit have been designed and simulated using the PSPICE software. The proposed circuit is capable to step-up regulated DC voltage up to 3.75V. The efficiency of the proposed circuit is greater than 65% following the simulation results. This work has focused on the application of micro-devices Wireless Sensor Network (WSN) device can be operated without battery. Streszczenie. W artykule opisano oszczednościowe źrodlo napiecia wykorzystujące jedynie sile temoelektryczną. Uklad elektroniczny startuje juz przy napieciu zasilania 0.1V i potrafi wytworzyc wyjściowe napiecie o poziomie blisko 4 V. Jako zastosowanie ukladu przewiduje sie mozliwośc zasilania czujnikow bezprzewodowych jedynie z baterii slonecznej. (Bezbateryjny przeksztaltnik napiecia termoelektrycznego o poziomie 0.1V na sygnal napieciowy o poziomie kilku woltow)

Thermoelectric energy harvesting system for demonstrating autonomous operation of a wireless sensor node enabled by a multipurpose interface

This paper demonstrates the autonomous operation of a wireless sensor node exclusively powered by thermoelectric energy harvesting. Active operation of a wireless sensor system is demonstrated successfully by means of an on-line programmable emulation kit that enables various thermoelectric energy harvesting scenarios. Moreover, this emulation kit accomplishes autonomous wireless sensor node operation by interfacing a small-scaled thermogenerator via a CMOS integrated autonomous multipurpose energy harvesting interface circuit performing maximum power point tracking.

Designing a Battery-Less Piezoelectric based Energy Harvesting Interface Circuit with 300 mV Startup Voltage

This paper presents a designing a battery-less piezoelectric based energy harvesting interface circuits with 300mV step-up voltage. A technique (i.e., DC-DC Step-Up converter) has chosen for designing the startup voltage with low voltage energy (i.e., 300mV). The proposed method consumes very little power, and is especially suitable for the ambient environmental source, where energy harvested power is very low. The energy harvesting interface circuit consists of MOSFET bridge ac-dc rectifier, voltage regulator, dc-dc step-up converter and an energy storage device with capacitor at the output terminal, replacing this by external battery. This paper will study results these important issues regarding the efficiencies of the energy harvesting power conversion interface circuits considering the storage device low voltage. The achievement of our development circuit is able to boost up minimum 1.67 V for input DC voltage of 300mV. The overall circuit efficiency is greater than 80% following the simulation results. This research has focused on the application of Wireless Sensor Network (WSN) and bio-medical device can be operated without battery.

A highly efficient interface circuit for ultra-low-voltage energy harvesting

Based on SMIC 0.18μm standard CMOS technology, an input-powered vibrational energy harvesting interface circuit is proposed. It can be applied in energy harvesting devices for the extremely low voltage and high conversion rate. The simulation results show that the minimum input voltage could be as low as 0.15V by utilizing bulk-driven technique. Correspondingly, the voltage conversion efficiency can reach up to 80%. And the power conversion efficiency is also 80% when voltage equals to 0.25V. The proposed input-powered interface circuit, compared with the conventional output-powered circuits, can automatically shut down when the input voltage amplitude is low enough, thereby avoiding unnecessary energy loss.

A Battery-Less Thermoelectric Energy Harvesting Interface Circuit With 35 mV Startup Voltage

A battery-less thermoelectric energy harvesting interface circuit to extract electrical energy from human body heat is implemented in a 0.35 CMOS process. A mechanically assisted startup circuit enables operation of the system from input voltages as low as 35 mV. An efficient control circuit that performs maximal transfer of the extracted energy to a storage capacitor and regulates the output voltage at 1.8 V is presented.