Harvesting Circuit Research Articles

Sub-nA photovoltaic energy harvesting circuit for miniaturized battery-less sensor edges

Abstract In this letter, we report on the photovoltaic energy harvesting circuit for miniaturized, battery-less sensor devices. To accumulate nanowatt power from ultra-small photovoltaic cells, it is essential to reduce the minimum operating current of the energy harvesting circuit. To reduce the minimum operating current, we propose a dual-capacitance voltage monitor (DCVM) which can overcome the issue of the voltage drop caused by the shoot-through current for switching. We designed the energy harvesting circuit including the DCVM in a 180nm CMOS standard process, and successfully demonstrate the minimum operating current of 1 nA.

Comparative Analysis of an 8 – Stage Cockcroft Walton Voltage Multiplier and A Dickson Voltage Multiplier in The Context of Radio Frequency Energy Harvesting

Purpose: This study seeks to enhance voltage multipliers for Radio Frequency (RF) energy harvesting, with an emphasis on increasing the efficiency of harvested energy. This improvement is vital for sustainable energy applications and reducing environmental pollution caused by fossil fuels. Theoretical reference: RF energy harvesting technology is gaining recognition as a viable sustainable method for capturing ambient energy, with earlier research primarily focused on antenna and circuit design. Nonetheless, the effectiveness of energy harvesting is still constrained by inadequate power output. This study expands on prior research by directly comparing two commonly utilized voltage multipliers, the Cockcroft Walton and Dickson multipliers, in the context of RF energy harvesting. Method: The Cockcroft Walton and Dickson voltage multipliers were optimally designed using Multisim and their performance was analysed using MATLAB. The comparison was conducted at an input voltage of 1V within two frequency ranges: 85 MHz – 110 MHz (FM band) and 1.8 GHz – 3.0 GHz (4G band). Output voltages for both multipliers were recorded and compared across these frequency bands. Results and Conclusion: At an input voltage of 1V within the FM band (85 MHz – 110 MHz), the Dickson voltage multiplier outperformed the Cockcroft Walton multiplier, delivering an output voltage of 11.1V compared to 6.6V. However, in the 4G band (1.8 GHz – 3.0 GHz), the Cockcroft Walton multiplier was more effective, providing a maximum output voltage of 5.2V against Dickson's 4.1V. The study concludes that the Dickson multiplier is more suitable for harvesting RF energy from the FM band, while the Cockcroft Walton multiplier is better for 4G band energy harvesting. Implications of research: The findings suggest that different RF energy harvesting applications may benefit from distinct voltage multipliers, depending on the frequency band in question. This could guide the design of more efficient RF energy harvesting circuits in future technologies aimed at sustainable energy solutions. Originality/value: This study offers a direct comparison of two voltage multipliers under different RF frequency conditions, providing valuable insights into optimizing energy harvesting technologies for green energy applications. The results help advance the understanding of efficient circuit design for specific RF frequency bands, contributing to the development of more effective energy harvesting systems.

Design of 2.4 GHz RF to 1.33 V DC Conversion Circuit for Energy Harvesting

This paper presents the design of a circuit for energy harvesting that converts 2.4 GHz radio frequency (RF) to 1.33 V DC. The demand for self-sustainable low-power electronic devices requires power to be supplied continuously. The battery has a life circle and is not able to sustain for a long time. Therefore, radiofrequency (RF) is one of the energy sources that can be obtained at any desired voltage for no cost and is widely available. A voltage regulator, charge pump, and rectifier make up the suggested circuit. All circuits are designed using 0.13-μm CMOS process. To convert the antenna's 2.4 GHz RF voltage to DC voltage, an RF rectifier is needed. After the rectifier's DC voltage is increased by the charge pump, the voltage regulator regulates the DC output voltage to the intended output value. At the voltage regulator, the desired DC output voltage will be controlled. The simulation's outcome demonstrates that an RF-DC rectifier circuit operating at 2.4 GHz frequency and a 10 kΩ load resistor may provide a DC output voltage of 78.51 mV. Next, the charge pump increased the rectifier's output voltage to 1.39 V. Lastly, the voltage regulator controlled the charge pump's output to produce a steady DC output of 1.33 V.

A High-Efficiency Piezoelectric Energy Harvesting and Management Circuit Based on Full-Bridge Rectification

This paper presents a high-efficiency piezoelectric energy harvesting and management circuit utilizing a full-bridge rectifier (FBR) designed for powering wireless sensor nodes. The circuit comprises a rectifier bridge, a fully CMOS-based reference source, and an energy management system. The rectifier bridge uses a PMOS cross-coupled structure to greatly reduce the conduction voltage drop. The CMOS reference source provides the necessary reference voltage and current. The energy management system delivers a stable 1.8 V to the load and controls its operation in intermittent bursts. Fabricated with a 110 nm CMOS process, the circuit occupies an area of 0.6 mm2, and is housed in a QFN32 package. Test results indicate that under 40 Hz frequency and 4 g acceleration vibrations, the chip’s energy extraction power reaches 234 μW, with the load operating every 3 s at a supply voltage of 1.8 V. Thus, this FBR interface circuit efficiently harnesses the energy output from the piezoelectric energy harvester.

A passive self-excited oscillation AC low-voltage energy harvesting circuit without a bridge

Most current electromagnetic energy harvesters use capacitor voltage multipliers or boost circuits controlled by external signals to step up and store energy. However, for most low-voltage output electromagnetic energy harvesters, generating switching control signals and rectification results in significant energy loss. To reduce these losses, this paper proposes an AC boost circuit without additional power supply or rectifier bridge, designed for low-voltage electromagnetic energy harvesting. Both theoretical analysis and experimental results confirm the effectiveness of the proposed interface. The results show that the circuit can start self-excited boosting at an initial voltage of 0.48V and achieve an AC-DC conversion efficiency of 71.3 % within an input voltage range of 0–2.9V.

Design and analysis of a piezoelectric energy harvesting shock absorber for light truck applications

Vehicle suspension vibration is a prevalent form of oscillation, with approximately 22.5 % of automobile energy dissipated through suspension-induced vibration. This phenomenon suggests that recovering the energy dissipated by the suspension system holds significant potential. This paper introduces a novel piezoelectric energy harvesting shock absorber (EHSA) based on non-contact magnetic force for light truck applications. The vibration of the vehicle suspension system is transformed into the rotation of a ball screw, enabling the one-way high-speed output of the rotor through a one-way bearing and planetary gear mechanism. Based on the non-contact magnetic force, the piezoelectric patches generate frequent oscillations, and a novel energy harvesting circuit is designed that efficiently converts the output of multiple piezoelectric units into usable electricity. The damping and energy harvesting characteristics of the EHSA with different external and internal variables are explored. Under sinusoidal excitation of 40 mm amplitude and 0.4 Hz frequency, the EHSA achieves a maximum output power of 7.51 W, with an average output power of 1.89 W. Furthermore, under random action, the EHSA can successfully illuminate 824 LED lights, enabling the temperature and humidity sensor to function normally. These findings indicate that the proposed EHSA can effectively harness vehicle suspension vibration to power onboard self-powered appliances while offering a new design idea for integrating vibration energy harvesters into vehicles.

Aurivillius-Type SrBi4Ti4O15/PGA Composite Film-Based Flexible Triboelectric Nanogenerators for Energy Harvesting/Storage and Multipurpose Tap-Indication Transducer Applications.

Recent advancements in flexible triboelectric nanogenerators (TENGs) have widely focused on converting mechanical energy into electrical energy to power small wearable electronic gadgets and sensors. To effectively achieve this, an efficient energy-converted power management circuit is required. Herein, we report on Aurivillius-type strontium bismuth titanate (SrBi4Ti4O15) nanoparticles (SBT NPs)-loaded polyglucosamine (PGA) composite film-based flexible TENG to be used for energy harvesting/storage and biomechanical applications. Initially, SBT NPs were synthesized and then, different weight concentrations were loaded into PGA. The TENG devices were fabricated using different wt % composite films (SBT/PGA) and polydimethylsiloxane as positive and negative triboelectric layers, respectively, and aluminum was used as a conductive electrode attached to two tribo films. To evaluate the electrical output from the device, contact-separation operation mode was used. An optimized TENG consisting of 2 wt % SBT/PGA composite film produced the maximum electrical output voltage and current of approximately ∼239 V and ∼7.5 μA, respectively. Efficient TENG energy harvesting and storage circuits have been proposed for storing charges in capacitors and for operating electronic gadgets. The optimized TENG was employed to generate electrical energy from various biomechanical movements. Thereafter, the biodegradability of the composite film was also tested. The fabricated films were completely biodegraded within a few hours. Furthermore, the TENG was utilized as a tap-indication transducer for multipurpose switching applications.

Admittance-based equivalent circuit modeling of multi-patch piezoelectric energy harvesting plate

Abstract Harvesting energy from mechanical vibration using piezoelectric material is a common method to power small electronics and batteries. Implementation of multiple piezo-patches to plate-like structures increases the power capacity and frequency bandwidth of the energy harvester since multiple patches can capture more vibrational modes of the dense plate dynamics. To optimize the harvested electrical output using advanced harvesting circuits, equivalent circuit modeling (ECM) is a useful technique for representing the entire electromechanical system in circuit- simulator-software (LTspice). The ECM technique based on finite-element (FE) simulation has been used for plate-like structures with only one single-piezo-patch-harvester in the literature. However, when multiple patches are integrated into a plate-like structure, their coupling can cause charge cancelation, resulting in complex dynamics that cannot be handled by the existing ECM methods. This paper presents three new methodologies for extracting a multi-mode ECM of the harvesters (e.g.: multi-patch piezo-harvesters integrated into a plate), using an admittance-based system identification approach utilizing FE results. The first method incorporates the ECM of multi-patch harvester into a single ECM, so called OGC. It includes a circuit branch where multiple patches have only one ECM branch for each vibration mode, which requires less equivalent circuit elements and hence less computational cost. The second and third so-called respective ground uncoupled (RGU) and respective ground coupled (RGC) ECM methods generate circuit branches for each piezo-patch and for each vibration mode, whereby their electrical connection (e.g. parallel or series) is later configured in LTspice. The RGU method provides a general multi-patch modeling approach while RGC method provides ECM parameters for each patch simultaneously when they are all connected which is the case in network harvester analysis. The ECMs of parallel multi-patch harvesters are validated by system-level FE simulations. The proposed admittance-based ECM methods are reliable for deriving the system parameters of multi-patch harvesters.

Case study: Design and properties of acoustic energy harvester

Converting acoustic energy into electric energy can not only suppress environmental noise but also provide energy supply, which is a potential way to solve the bottleneck problem of energy supply in wireless sensor networks (WSNs). An acoustic energy harvester structure and circuit system combining Helmholtz resonance effect with piezoelectric effect are proposed in this article. The band gap characteristics of the designed acoustic energy harvester are analyzed by plane wave expansion (PWE) theory and experiment. The substrate of Helmholtz resonator is made from piezoelectric sheet, and the acoustic energy harvester structure is arranged periodically. When the incident noise frequency keeps coincidence with the resonant frequency, the conversion efficiency goes high up to 21.3%. The influence of series and parallel connection of piezoelectric elements on the acoustic to electric energy is observed. The AC-DC conversion circuit is designed with rectifier bridge, and the energy storage circuit is designed with supercapacitor. The power obtained from the acoustic to electric energy conversion system is 1523 mW. Application tests indicate that the noise suppresses, energy conversion, and energy storage can be realized at the same time by the proposed acoustic energy harvester system.

Robustness analysis for the vibration control performance of energy-harvesting tuned mass damper with uncertainties

Energy-harvesting vibration control strategy has been proposed and applied in different applications, including but not limited to automotive, mechanical, and civil engineering. However, when facing uncertainties from both internal and external environments, the robustness of its performance has rarely been evaluated. The energy-harvesting tuned mass damper (EHTMD) is a representative vibration control device integrated with the energy-harvesting function. This study investigates the robustness of an EHTMD installed on a structure with multi-uncertainties. First, the EHTMD modeling, the interval model, and the robustness evaluation framework are introduced. Uncertainties are considered for all parameters of an EHTMD, including the mechanical units, electromagnetic damper, and energy harvesting circuit. Subsequently, a series of dynamic simulations are performed on a damped benchmark single-degree-of-freedom frame with an EHTMD. The lower- and upper-bound structural vibration and generated power are estimated under free-vibration, harmonic-excitation, and random-excitation scenarios. The EHTMD performance robustness is evaluated through the interval response by incorporating the first-passage theory. The key factors in EHTMD that influence its robustness are identified. Results indicate promising robustness when using the energy-harvesting vibration control strategy to replace the conventional dampers, addressing one of the often-questioned issues of the energy-harvesting vibration control strategy.

Piezoelectric energy harvester for wind turbine blades based on bistable response of a composite beam in post-buckling

A bistable piezoelectric energy harvester (PEH) is presented for harvesting power from vibrations occurring at low frequencies, as is the case of wind turbine blades. The axial compressive prestress of a piezoelectric composite beam at post-buckling serves as the bistability source, leading to high mechanical to electric power conversion. An in-house harvesting circuit connected to the piezoelectric terminals is used for demonstration of its harvesting power capabilities. A finite element (FE) model is used to analyze and optimize the coupled nonlinear electromechanical response of the PEH, including structure and circuit. A physical prototype has been manufactured and tested for validation of the electromechanical design and the FE modeling approach. Predictions and measurements indicate an increase of harvested power with applied prestress up to a transition point, where a sudden drop in power occurs. Good comparison between numerical and experimental results verified the modeling approach, whereas deviations related to physical boundary conditions at large compressive forces affected the prediction of the transition point in harvested power. The harvester produced 1.32 mW of electrical power under tonal base excitation of 1 g at 8 Hz. Hence, the nonlinear PEH has demonstrated its capability to harvest energy at frequencies much lower than its first linear modal frequency and could thus serve as a promising solution for powering IoT devices and sensors in large vibrating structures.

Voltage–Resistance-Adaptive MPPT Circuit for Energy Harvesting

Voltage–Resistance-Adaptive MPPT Circuit for Energy Harvesting

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

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices.

A compact self-powered inductor-less piezoelectric energy harvesting circuit using gyrator

In traditional low-frequency energy harvesting circuits, a large matched inductor with a large size is unavoidable. To reduce the size of the circuit, this paper proposes a compact self-powered inductor-less high-efficiency piezoelectric energy harvesting circuit using a low-power-consumption gyrator. A self-powered floating gyrator inductor is used in place of an inductor in the proposed circuit, and the required phasor response is acquired by using its voltage–current (V–I) relationship. The proposed circuit offers easy adjustability and performance benefits in small integrated circuits packages. The proposed circuit can be cost-effective and provide reduced area advantages in autonomous self-powered Internet-of-Things and wireless sensor nodes applications. Regarding harvested energy, the proposed circuit with a storage capacitor of 0.24 F can obtain 320% improved performance than standard energy harvesting along with the lowest power consumption of 0.25 µW in self-powered operation. The proposed technique can also be applied to similar piezoelectric energy harvesting strategies with large inductors.

Self‐Powered Vibration Frequency Monitoring Device for the Grid Based on Triboelectric Nanogenerator and Micro Thermoelectric Generator

AbstractThe galloping of transmission lines (GTLs) has a significant impact on the development of smart grids. However, traditional vibration frequency monitoring devices for transmission lines suffer from issues such as low measurement accuracy, high environmental requirements, and the inability to achieve self‐powering. A self‐powered vibration frequency monitoring method is proposed based on frequency‐sensing triboelectric nanogenerator (F‐TENG) and micro thermoelectric generators (MTEG). Models for vibration frequency sensing based on F‐TENG and energy capture based on MTEG are established. A flexible self‐powered sensing prototype, integrating F‐TENG, MTEG, and a Signal processing and Energy harvesting Circuit (SEC), is fabricated. Additionally, an innovative solvothermal method for the preparation of MTEG materials is presented, resulting in Bi2Te3‐based thermoelectric materials with significantly high thermoelectric conversion performance. Experimental results demonstrate that within the range of 0.1–5.1 Hz, F‐TENG can precisely perceive the frequency of GTLs, with a maximum error of 1.274%. MTEG achieves a maximal open‐circuit voltage of 3.282 V. Finally, the SEC unit is designed to couple the outputs of F‐TENG and MTEG for frequency calculation and wireless transmission to a microcontroller. This device provides an efficient solution for monitoring the frequency of GTLs and offers robust support for the stability of the smart grid.

Evolutionary algorithm for minimizing the temperature influence of low power RF Energy Harvesting circuits

The aim of this work is to analyze and optimize the design of low-power Radio Frequency (RF) Energy Harvesting rectifiers by using an Evolutionary Algorithm. Although, generally neglected in the literature, the RF rectifier operation strongly depends on the operation temperature. When it varies, the input impedance can change significantly, affecting the circuit matching and its power conversion efficiency. In this work, an evolutionary algorithm is used to identify which parameters of an RF diode are responsible for the performance degradation as a function of temperature and to optimize the rectifier circuit in order to reduce the temperature influence. This work demonstrates that the saturation current, the zero-bias junction capacitance, the load and the series resistance have an important impact in designing an optimized circuit. Results indicate that the applied algorithm can be used aiming the project of a circuit more robust to temperature variations. The obtained results have also been compared to experimental ones, corroborating the analysis.

A complete artificial intelligence pipeline for radio frequency energy prediction in cellular bands for energy harvesting systems

Radio Frequency (RF) energy harvesting has been used to power wireless and low-powered devices. However, RF energy harvesting has limitations in terms of the amount of power that can be collected based on signal availability. Hence, energy prediction is essential to improve energy harvesting circuits' performance. Previous research has mainly focused on improving power harvesting policies or theoretically estimating the harvested energy. Very few works have considered the prediction of the RF signal as time series data using real RF measurements. Moreover, challenges such as the power consumed by the circuit's harvesting decisions and the impact of outliers on the model performance haven't been addressed yet. This paper presents a complete pipeline for developing the best predictive model for RF energy in cellular frequency bands. Real-time measurements are taken in different frequency bands using software-defined radio technology. We use four artificial intelligence techniques to model the RF energy signal. Additionally, we propose an optimized model with an enhanced loss function, which makes the model more resilient to anomalies, saving computational power and time consumed in cleaning the data. The four algorithms are investigated, and their prediction accuracies are compared. The average power of a period of 5 min is accurately forecasted. Numerical results in the 1960 MHz band show that long short-term memory has the best performance, followed by the DeepAR algorithm with prediction accuracies of 95.76% and 95.02%, respectively. Moreover, the proposed optimized model showed a 32.2% lower prediction error than the traditional models.

Maximizing Electric Power Recovery through Advanced Compensation with MPPT Algorithms

The present investigation introduces an advanced methodology for maximum power point tracking (MPPT) applied to a piezo harvester scheme. A comprehensive rectifier circuit, equipped with an embedded MPPT component, is established to optimize energy production by monitoring a DC-DC inverter connected to the rectifier. Furthermore, the system’s sensitivity error has been finely tuned to dynamically adjust its impedance unit in real time, thereby optimizing load acquisition. This innovative approach seamlessly integrates the MPPT algorithm into the piezo harvester circuit. Moreover, the vehicle’s road handling is significantly augmented through the incorporation of a robust steering front and an active differential control system. Leveraging the MPPT module, the rectifier consistently achieves a power recovery efficiency exceeding 85%, independent of varying load conditions. Additionally, a DC-DC converter circuit has been seamlessly integrated to finely adjust the output voltage to meet specified levels. Numerical simulations demonstrate the effectiveness of the harvesting scheme, extracting a substantial output power of 90 W with an overall efficiency of 70%. The improved MPPT approach, employing angles of arrival (AoA) DV-Hop control strategies, minimizes the system’s power consumption based on the Global Positioning System (GPS). The utilization of Harris Hawks optimization (HHO) and the generation of quadrants in the four-quadrant operation mode of DC motors in the wireless sensor network (RCSFs) have been significantly enhanced in this study. Simulations reveal that, at a velocity of 50 km/h, shock absorbers utilizing the received signal strength indication (RSSI) can harvest between 60 and 90 W on a class C road, based on the time of arrival (TOA). Striking a balance in ride comfort using the time difference of arrival (TDOA) as a trade-off constitutes approximately 30% of the piezoelectric harvester (PEH) system’s power consumption when operating in active suspension mode, optimized by particle swarm optimization (PSO).

Monolithic Integration of a Microwave Amplifier and a Multisource Energy Harvesting Circuit

Monolithic Integration of a Microwave Amplifier and a Multisource Energy Harvesting Circuit

Experimental investigation of near-field magnetic energy harvesting from induction cooktop

This paper proposes a simple and cost-effective magnetic-field-energy harvesting circuit for capturing the leaked magnetic energy from an induction cooktop. In this, the captured energy is converted into dc electrical energy with the help of 1N5819 Schottky diodes based full wave bridge rectifier. We investigated the captured magnetic-field energy at different positions and different heights of the energy-harvesting coil from the induction cooktop. The designed Magnetic-Field-Energy Harvesting (MFEH) circuit is capable of capturing an average dc power of 1484 mW while it is placed 5 cm below the induction cooktop with a load resister 33 Ω and capacitance of 470 μF. The power level is reduced to 203 mW when the energy harvesting coil is moved to 10 cm below the induction cooktop. The harvested magnetic field energy at different positions of the energy harvesting coils is investigated for different values of load resisters. The harvested energy can be stored in a battery for future applications. The proposed device demonstrated practically for charging mobile and powering the low-power IoT device. The numerical study of the proposed harvesting mechanism is explained also. The induction cooktop’s yielded excellent results and magnetic field energy harvesting capability make the proposed device unique from the previously reported magnetic harvesting circuits.