Management Circuit Research Articles

Ferromagnetic nanoparticle-embedded hybrid nanogenerator for harvesting omnidirectional vibration energy.

A new form of generator known as the triboelectric nanogenerator (TENG) has recently been suggested as a simple and low-cost solution to scavenge ambient mechanical energy. Although there have been substantial advances in TENGs over the past few years, the power efficiency of TENGs must be enhanced further before they can be practically applied. In the present study, we report a ferromagnetic nanoparticle-embedded hybrid nanogenerator (FHNG) which operates based on both triboelectricity and electromagnetic induction. A TENG and an electromagnetic generator (EMG) efficiently cooperate to generate electrical energy from the same motion, i.e., the vibration of a synthesized nanoparticle. A surface-functionalized ferric oxide nanoparticle, which has strong ferromagnetism and high triboelectricity, was produced by a simple surface-coating process. The measured electrical characteristics revealed that the output voltage of both the TENG and the EMG components increased by approximately 50 times and by twofold, respectively, after the surface functionalization step. Moreover, when constant vibration of 3 Hz is applied to the fabricated FHNG, the TENG and EMG components correspondingly generated output power of 133.2 μW at a load resistance of 100 MΩ and 6.5 μW at a load resistance of 200 Ω. The output power per unit mass from the FHNG is greater than that according to the arithmetic sum of the individual TENG and EMG components, demonstrating synergy between the two components. Furthermore, the device can generate stable output under various vibration directions, amplitudes, and frequencies due to the fluid-like characteristics of the powder. The packaged structure also securely protects the device from external humidity and dust. Connected to a rationally designed power management circuit, a digital clock was turned on solely by the fabricated FHNG.

State-of-the-Art Power Management Circuits for Piezoelectric Energy Harvesters

Piezoelectric energy harvesters scavenging energy from the environment have been a promising solution to satisfy the increasing power demand in wireless sensor nodes. Power conditioning circuits for piezoelectric energy harvesters are a burgeoning technology widely disclosed in literature since 2001; however, there is still no complete overview available, which exhaustively describes the cutting-edge status of the research on power conditioning for piezoelectric energy harvesters. This paper aims at providing a more complete review on the state-of-the-art piezoelectric energy harvesting interfaces. A systematic categorization of the piezoelectric energy harvesting approaches is presented, based on the qualitative working principle, adopted control scheme, and employed components. The presented power conditioning interfaces are commented and discussed in detail, addressing the strengths and weaknesses based on the achieved results. Furthermore, this paper performs a critical comparison of state-of-the-art techniques by employing seven criteria to evaluate the performance of an energy harvesting system. The observed trend in this field is to design harvesting rectification schemes by employing Maximum Power Point Tracking (MPPT) algorithms to achieve a high Power Conversion Efficiency (PCE) and, resonant rectification techniques to harvest efficiently energy from wide-band excitations.

Aeroelastic flutter energy harvesters self-polarized by triboelectric effects

This paper presents the performances of several electrostatic flutter energy harvesters tested in a wind tunnel between 0 and 20 m s−1. The main idea is to use the flutter capability of thin flexible films confined between lateral walls to induce simultaneously the capacitance variations and the electrostatic polarization required by the triboelectric/electrostatic conversion. This technology provides thin and flexible devices and solve the electret’s stability issue (Perez et al 2015 Smart Mater. Struct., Perez et al 2015 New Circuits and Systems). Our prototypes (<16 cm2) have a quick startup (from 3 m s−1) and an electrical power-flux density from 0.35 μW cm−2@3 m s−1 (light breeze) to 35 μW cm−2@20 m s−1 (fresh gale). A Maximum Power Point circuit has been developed to efficiently use the power provided by the energy harvesters. The energy harvester combined with its power management circuit has finally been used to supply an 868 MHz wireless sensor node with temperature and acceleration measurements, validating the complete energy harvesting chain.

A Novel Passive Wireless Sensing Method for Concrete Chloride Ion Concentration Monitoring.

In this paper, a novel approach for concrete chloride ion concentration measuring based on passive and wireless sensor tag is proposed. The chloride ion sensor based on RFID communication protocol is consisting of an energy harvesting and management circuit, a low dropout voltage regulator, a MCU, a RFID tag chip and a pair of electrodes. The proposed sensor harvests energy radiated by the RFID reader to power its circuitry. To improve the stability of power supply, a three-stage boost rectifier is customized to rectify the harvested power into dc power and step-up the voltage. Since the measured data is wirelessly transmitted, it contains miscellaneous noises which would decrease the accuracy of measuring. Thus, in this paper, the wavelet denoising method is adopted to denoise the raw data. Besides, a monitoring software is developed to display the measurement results in real-time. The measurement results indicate that the proposed passive sensor tag can achieve a reliable communication distance of 16.3 m and can reliably measure the chloride ion concentration in concrete.

Design of Solar Power Management Circuit Based on Wireless Sensor Network

To explore the design of solar power management circuit, the fuzzy logic control algorithm based on MPPT (max power point tracking), which has fast control speed and good environment robustness, is adopted as the control algorithm. In addition, the MPPT solar battery charge and discharge power management circuit is designed and successfully applied in the on-line measurement projects of dielectric loss of wireless sensor network in Jilin Province LG Electronics Company. The results show that the charging efficiency of solar battery charge and discharge power management circuit can reach above 80%, and the current of static power management circuit is less than 1mA. In different light intensities, the dynamic power management is intelligently carried out. At last, it is concluded that the stability and reliability of circuit are quite high.

Ag Nanoparticle-Based Triboelectric Nanogenerator To Scavenge Wind Energy for a Self-Charging Power Unit.

Li-ion batteries are a green energy storage technology with advantages of high energy density, long lifetime, and sustainability, but they cannot generate electric energy by themselves. As a novel energy-harvesting technology, triboelectric nanogenerators (TENGs) are a promising power source for supplying electronic devices, however it is difficult to directly use their high output voltage and low output current. Here, we designed a Ag nanoparticle-based TENG for scavenging wind energy. After including a transformer and a power management circuit into the system, constant output voltages such as 3.6 V and a pulsed current of about 100 mA can be obtained, which can be used to directly light up a light-emitting diode. Furthermore, the produced electric energy can be effectively stored in a WO3/LiMn2O4 electrode based Li-ion battery. Our present work provides a new approach to effectively scavenge wind energy and store the obtained electric energy, which is significant for exploring self-charging power units.

A triple hybrid micropower generator with simultaneous multi-mode energy harvesting

This study presents a triple hybrid energy harvesting system that combines harvested power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters into a single DC supply. A power management circuit is designed and implemented in 180 nm standard CMOS technology based on the distinct requirements of each harvester, and is terminated with a Schottky diode to avoid reverse current flow. The system topology hence supports simultaneous power generation and delivery from low and high frequency vibrations as well as temperature differences in the environment. The ultra-low DC voltage harvested from TE generator is boosted with a cross-coupled charge-pump driven by an LC oscillator with fully-integrated center-tapped differential inductors. The EM harvester output was rectified with a self-powered and low drop-out AC/DC doubler circuit. The PZT interface electronics benefits from peak-to-peak cycle of the harvested voltage through a negative voltage converter followed by synchronous power extraction and DC-to-DC conversion through internal switches, and an external inductor. The hybrid system was tested with a wearable in-house EM energy harvester placed wrist of a jogger, a commercial low volume PZT harvester, and DC supply as the TE generator output. The system generates more than 1.2 V output for load resistances higher than 50 kΩ, which corresponds to 24 μW to power wearable sensors. Simultaneous multi-mode operation achieves higher voltage and power compared to stand-alone harvesting circuits, and generates up to 110 μW of output power. This is the first hybrid harvester circuit that simultaneously extracts energy from three independent sources, and delivers a single DC output.

Impact-Based Electromagnetic Energy Harvester with High Output Voltage under Low-Level Excitations

To expand the applications of vibrational energy harvesters (VEHs) as power sources of wireless sensor nodes, it is of significance to improve the scavenging efficiency for the broadband, low-frequency, and low-level vibrational energy. The output voltages of electromagnetic vibrational energy harvesters (EMVEHs) are usually low, which complicates the power management circuit by an indispensable voltage boosting element. To this end, an impact-based non-resonant EMVEH mainly composed of an outer frame and an inner frame on rollers is proposed. Numerical simulations based on a mathematical model of the harvester are conducted to analyze the effects of structural parameters on the output performance. Under base excitation of 0.1 and 0.3 (where g is the gravitational acceleration, 1 g = 9.8 m · s − 2 ), the experimental maximum root mean square voltages of a harvester prototype across a resistor of 11 kΩ are as high as 7.6 and 16.5 V at 6.0 and 8.5 Hz, respectively, with the maximum output powers of 5.3 and 24.8 mW, or the power densities of 54.6 and 256 μW cm−3. By using a management circuit without a voltage boosting element, a wireless sensor node driven by the prototype can measure and transmit the temperature and humidity every 20 s under base excitation of 0.1 g at 5.4 Hz.

Self-Powered RFID Sensor Tag for Fault Diagnosis and Prognosis of Transformer Winding

This paper presents a transformer winding fault diagnosis and prognosis method based on self-powered radio frequency identification (RFID) sensor tag. The proposed RFID sensor tag, which consists of RFID tag, power management circuit, MCU, and accelerometer, can acquire the vibration signals of transformer winding from the tank by accelerometer, and then wirelessly transmit the signals to the RFID reader. An inductive energy harvester utilizing surrounding magnetic field is optimized as power supply for the proposed sensor tag, including the MCU and the accelerometer. A customized ac–dc converter together with a low-dropout voltage regulator is designed to provide stable dc voltage for the proposed sensor tag. The RFID reader compiles the data from all the RFID sensor tags and then transmits them to the remote monitoring software which is developed to display the diagnosis results and alert messages. The experimental results show that the proposed energy harvester can provide 197- $\mu \text{w}$ power in a 50-Hz magnetic field, and the ac–dc converter is capable of providing 2.5-V dc voltage to power the circuitry. The measured maximum power consumption of the proposed sensor tag is 147 $\mu \text{w}$ . Furthermore, the achieved reliable communication distance is 13 m in the test scenario. The experimental results show that the proposed method is effective in term of the diagnosis and prognosis of transformer winding.

A New Type of Self Driven Door Handle

In this article, authors report on a smart door handle that can efficiently collect and utilize ambient energy to power itself. A Triboelectric Nanogenerator which presents characteristics including easy fabrication, small size and light weight is embedded in the door. When begin to turn the handle, the TENG can convert the mechanical energy into the electrical energy, and the power can up to 0.023W. At the same time, the internal circuit will send a single to identify the action of opening the door, and then the wireless receiver will make appropriate responses after receiving the signal. In this article, the authors designed a wireless transmission circuit to ensure that the transmitter and receiver can communicate in real time. Due to the TENG's output is AC signal which can't power the device directly, so the power management circuit was designed to process the signal. To analyze and compare the output signal, the authors designed two power management circuits. Both the circuits can convert the AC signal into the DC signal, the voltage can up to 5V and the current can up to 3mA.

Autonomous Sensors Powered by Energy Harvesting from von Karman Vortices in Airflow.

In this paper an energy harvesting system based on a piezoelectric converter to extract energy from airflow and use it to power battery-less sensors is presented. The converter is embedded as a part of a flexure beam that is put into vibrations by von Karman vortices detached from a bluff body placed upstream. The vortex street has been investigated by Computational Fluid Dynamics (CFD) simulations, aiming at assessing the vortex shedding frequency as a function of the flow velocity. From the simulation results the preferred positioning of the beam behind the bluff body has been derived. In the experimental characterization the electrical output from the converter has been measured for different flow velocities and beam orientations. Highest conversion effectiveness is obtained by an optimal orientation of the beam, to exploit the maximum forcing, and for flow velocities where the repetition frequency of the vortices allows to excite the beam resonant frequency at its first flexural mode. The possibility to power battery-less sensors and make them autonomous has been shown by developing an energy management and signal conditioning electronic circuit plus two sensors for measuring temperature and flow velocity and transmitting their values over a RF signal. A harvested power of about 650 μW with retransmission intervals below 2 min have been obtained for the optimal flow velocity of 4 m/s.

A power management circuit with 50% efficiency and large load capacity for triboelectric nanogenerator

Recently, triboelectric nanogenerators (TENGs), as a collection technology with characteristics of high reliability, high energy density and low cost, has attracted more and more attention. However, the energy coming from TENGs needs to be stored in a storage unit effectively due to its unstable ac output. The traditional energy storage circuit has an extremely low energy storage efficiency for TENGs because of their high internal impedance. This paper presents a new power management circuit used to optimize the energy using efficiency of TENGs, and realize large load capacity. The power management circuit mainly includes rectification storage circuit and DC–DC management circuit. A rotating TENG with maximal energy output of 106 mW at 170 rpm based on PCB is used for the experimental verification. Experimental results show that the power energy transforming to the storage capacitor reach up to 53 mW and the energy using efficiency is calculated as 50%. When different loading resistances range from 0.82 to 34.5 k are connected to the storage capacitor in parallel, the power energy stored in the storage capacitor is all about 52.5 mW. Getting through the circuit, the power energy coming from the TENGs can be used to drive numerous conventional electronics, such as wearable watches.

Circuit and System Designs of Ultra-Low Power Sensor Nodes With Illustration in a Miniaturized GNSS Logger for Position Tracking: Part II—Data Communication, Energy Harvesting, Power Management, and Digital Circuits

This two-part paper reviews recent innovations in circuit design that have accelerated the miniaturization of sensor nodes. In this second part of the paper, we focus on key building blocks of miniaturized sensor nodes, such as data transceivers, energy harvesters, power management units, and digital logic circuits. System level design considerations are also discussed to provide guidelines for the design of a miniaturized system. As an example prototype design, a 2.7-cm3 global navigation satellite system (GNSS) logger is proposed. This paper includes a die-stacked sensor platform composed of an ARM cortex M0 processor, energy harvester, power management unit, solar cell, optical receiver, sensor layer, and RF transmitter that exploits the discussed design techniques for ultra-low power operation. The GNSS logger can store GNSS signals of >1 k positions on a single battery charging without additional energy harvesting.

Triboelectric Nanogenerator Enabled Body Sensor Network for Self-Powered Human Heart-Rate Monitoring.

Heart-rate monitoring plays a critical role in personal healthcare management. A low-cost, noninvasive, and user-friendly heart-rate monitoring system is highly desirable. Here, a self-powered wireless body sensor network (BSN) system is developed for heart-rate monitoring via integration of a downy-structure-based triboelectric nanogenerator (D-TENG), a power management circuit, a heart-rate sensor, a signal processing unit, and Bluetooth module for wireless data transmission. By converting the inertia energy of human walking into electric power, a maximum power of 2.28 mW with total conversion efficiency of 57.9% was delivered at low operation frequency, which is capable of immediately and sustainably driving the highly integrated BSN system. The acquired heart-rate signal by the sensor would be processed in the signal process circuit, sent to an external device via the Bluetooth module, and displayed on a personal cell phone in a real-time manner. Moreover, by combining a TENG-based generator and a TENG-based sensor, an all-TENG-based wireless BSN system was developed, realizing continuous and self-powered heart-rate monitoring. This work presents a potential method for personal heart-rate monitoring, featured as being self-powered, cost-effective, noninvasive, and user-friendly.

A high-efficiency self-powered wireless sensor node for monitoring concerning vibratory events

This paper presents a self-powered wireless alarming sensor node (SWASN), which was designed to monitor the occurrence of concerning vibratory events. The major components of the sensor node include a vibration-threshold-triggered energy harvester (VTTEH) that powers the sensor node, a dual threshold voltage control circuit (DTVCC) for power management and a radio frequency (RF) signal transmitting module. The VTTEH generates significant electric energy only when the input vibration reaches certain amplitude. Thus, the VTTEH serves as both the power source and the vibration-event-sensing element for the sensor node. The DTVCC was specifically designed to utilize the limited power supply from the VTTEH to operate the sensor node. Constructed with only voltage detectors and MOSFETs, the DTVCC achieved low power consumption, which was 65% lower compared with the power management circuit designed in our previous work. Meanwhile, a RF transmit circuit was constructed based on the commercially available CC1110-F32 wireless transceiver chip and a compact planar antenna was designed to improve the signal transmission distance. The sensor node was fabricated and was characterized both in the laboratory and in the field. Experimental results showed that the SWASN could automatically send out alarming signals when the simulated concerning event occurred. The waiting time between two consecutive transmission periods is less than 125 s and the transmission distance can reach 1.31 km. The SWASN will have broad applications in field surveillances.

Electric field energy harvesting under actual three‐phase 765 kV power transmission lines for wireless sensor node

For the first time, under the actual three-phase 765 kV power transmission lines, electric field energy is harvested and Zigbee-based sensor node powered by the harvested energy is operated autonomously. A conductor tube is placed between power lines and the earth surface for electric field energy harvesting. The voltage difference between conductor tube and the earth surface is rectified and the harvested electric energy is stored in a storage capacitor. A self-sustaining power management circuit adopting low-power comparator with hysteresis is devised to monitor the stored energy and to operate the sensor node autonomously according to the stored energy. Experimental results under the actual three-phase 765 kV power lines show that the data transfer period is almost inversely proportional to the square of the height of the sensor module from the earth surface. The temperature data is transmitted in every 25 s when the conductor tube is located at 4 m from the earth surface. Since the presented non-contact energy harvesting apparatus is very simple, robust and low-cost, it is believed that the presented technology can be widely applied to power transmission, distribution and smart grid system.

Single- and multi-source battery-less power management circuits for piezoelectric energy harvesting systems

This paper presents a battery-less power management unit for piezoelectric energy harvesting which exploits a diode-based rectifier, a storage capacitor, and a custom trigger circuit to extract energy from a piezoelectric converter and to intermittently power an electronic load. The low power consumption and the high versatility of the power management unit allow its implementation within single- and multi-source power management circuits for piezoelectric converters.Experimental results show that the proposed single-source power management circuit is able to extract energy from a piezoelectric converter excited by sinusoidal vibrations with an acceleration amplitude of 0.5gRMS in the frequency range between 38 and 49Hz, yielding an operating bandwidth of 12Hz. Such operating bandwidth is up to 71.4% greater than tailored commercial energy harvesting solutions under the same experimental conditions.Innovative multi-source power management circuits which exploit the series-like and parallel-like combinations of multiple power management units are presented. The limitations of traditional topologies are overcome by connecting each piezoelectric converter to a power management unit. In particular, the proposed inverting, buck-boost, parallel-like, power management circuit combines the energy from the storage capacitors of each power management unit in a single storage capacitor exploiting a switch on inductor through trigger circuits. Experimental results show that the proposed inverting buck-boost power stage has an overall efficiency of about 8.5%.

An RF-Powered DLL-Based 2.4-GHz Transmitter for Autonomous Wireless Sensor Nodes

This paper presents the system and circuit design of a compact radio frequency (RF)-powered 2.4-GHz CMOS transmitter (TX) to be used for autonomous wireless sensor nodes (WSNs). The proposed TX utilizes the received dedicated RF signal for both energy harvesting as well as frequency synthesis. A TX RF carrier is derived from the received RF signal by means of a delay locked loop and XOR-based frequency multiplier. The 50- $\Omega $ load is subsequently driven by a tuned switching RF power amplifier (PA) with 25% duty cycle input for high global efficiency. The design is fabricated in 40-nm CMOS technology and occupies a die area of 0.16 mm2. Experimental results show a rectifier with 36.83% peak efficiency and power management circuit with 120-nA current consumption that enables a low start-up power of −18.4 dBm. The TX outputs a continuous 2.44-GHz RF signal at −2.57 dBm with 36.5% PA drain efficiency and 23.9% global efficiency from a 915-MHz RF input and supports ON–OFF keying modulation.

A new nano-power trigger circuit for battery-less power management electronics in energy harvesting systems

This paper presents a solution for battery-less power management circuits for micro-power energy converters, allowing energy harvesting systems to operate under continuous and intermittent conditions. The proposed trigger circuit is a fully passive, normally open, single pole, single throw, analog switch driven by a nano-power CMOS control unit. The trigger circuit starts in an OPEN state until the voltage, at its input terminal, reaches a high threshold, when it toggles to the CLOSED state. Once the input voltage drops below a low threshold, the trigger circuit returns to the OPEN state. In the CLOSED state, the trigger circuit creates a low resistance path between the input and output terminals, while at the OPEN state the input is isolated from the output. A first prototype was breadboarded by using discrete components for the sake of performance evaluation. Low threshold voltages (2.15V and 1.15V), sub-ohm CLOSED-state resistance, and power consumption requirements (in the order of 55.9 and 167.7nW), coupled with relatively high energy extraction capabilities are confirmed by experimental results. These features put our proposed circuit among the best of its kind in the state-of-the-art circuits.To prove the effectiveness of the proposed trigger circuit, we have included it into a custom battery-less power management circuit for a piezoelectric energy harvesting system. The system was proven to work even under intermittent operating conditions, and lock-up phenomena, related to current surge effect, were avoided.

A Novel Power Management Circuit Using a Super-Capacitor Array for Wireless Powered Capsule Robot

Wireless power transmission (WPT) based on near-field inductive coupling principle is a promising solution to the power supply issue of a freely moving capsule robot (CR) that employs dc motors as actuators. However, the limited inductive power can cause a voltage drop when dc motors start or stall, because short-time peak power is required. To handle the voltage drop issue, we propose the use of a novel power management circuit (PMC) that consists of four successively connected segments of a full-bridge rectifier for ac–dc conversion, a buck dc–dc converter for highly efficient voltage reduction, a power buffer for power storage and short-time power supply, and a low drop-out (LDO) regulator for voltage stabilization. The power buffer is implemented with a super-capacitor array (SCA) that employs the output voltage of the dc–dc converter as its charging voltage. To analyze and optimize the PMC containing the SCA (PMC-SCA), a model is built based on deducing the input resistance relations between each pair of adjacent segments, and its correctness is then validated experimentally. A comparison between the PMC-SCA and the traditional PMC (a rectifier + a regulator) is also conducted, and the former shows superiorities in both reducing voltage drop and improving safety related to temperature rise of onboard receiving coil (RC). Finally, a primary PMC-SCA prototype measuring $\Phi $ 13 mm $ \times $ 4 mm is integrated to an inchworm-like CR for effectiveness validation; the CR working voltage is measured to be higher than 3 V at all times, which ensures the proper functioning of the CR.