Synchronous Charge Extraction Research Articles

A 0.25-μm HV-CMOS Synchronous Inversion and Charge Extraction Interface Circuit With a Single Inductor for Piezoelectric Energy Harvesting

A 0.25-μm HV-CMOS Synchronous Inversion and Charge Extraction Interface Circuit With a Single Inductor for Piezoelectric Energy Harvesting

Synchronized charge extraction circuit for electret‐based vibration energy harvester

AbstractImpedance matching is one outstanding issue for the electret‐based vibration energy harvester (eVEH) due to its small equivalent capacitance. In this paper, the authors developed a synchronized charge extraction (SCE) circuit for eVEH, to improve its performance in small load resistance conditions. An electromagnetic detector is embedded with the eVEH to detect its maximum vibration amplitude. The synchronized switch is controlled by a microcontroller unit. According to the authors’ simulation study, the power output of eVEH interfaced with the SCE circuit is three times larger than that of the standard circuit, which proved the effectiveness of our SCE circuit.

Bidirectional Thermoelectric Assisted Synchronous Charge Extraction Circuit Based on Buck Structure for Piezoelectric Energy Harvesting

Energy harvesting technology is currently a research hotspot, which can effectively solve energy supply problems in fields such as wireless sensor networks, wearable devices, and smart homes. An energy harvesting system using a thermoelectric generator (TEG) for energy assistance of a piezoelectric transducer (PZT) is proposed. It employs a synchronous charge extraction circuit based on a buck structure (BUCK-SECE), which uses thermoelectric energy to inject energy into the piezoelectric element in both directions to boost the initial voltage of the BUCK-SECE, increasing its output power. The experimental results demonstrate that the utilization of thermoelectric energy can increase the output power of BUCK-SECE by a factor of 3.3 under low-vibration conditions and by a factor of 0.8 under high-vibration conditions. Therefore, the proposed energy harvesting system in this article can effectively enhance the output power of piezoelectric energy transducers and yield desirable performance in real-world applications.

Bias-Voltage-SSHI Interface Circuit for Strong Coupling Piezoelectric Energy Systems

Compared with the standard extraction interface circuit (SEH), the harvested energy and harvested power of synchronized switching harvesting interface circuits (SSHI) and synchronous charge extraction interface circuit (SECE) cannot improve more effectively. This paper proposes a Bias-Voltage-SSHI Interface Circuit (BV-SSHI), consisting of a single peak voltage detection switch and a rectifier, to solve this problem. The proposed BV-SSHI improves the output voltage by biasing the voltage of the piezoelectric energy harvester and obtains similar harvested power as SSHI. Simulation results show that the BV-SSHI can obtain more harvested energy and harvested power than SEH under weak, medium, and strong coupling systems. Results show that the higher harvester's voltage and the larger phase difference cause the electrical restoring force (χV) to significantly weaken the vibration displacement, especially under strong coupling systems. Thus, the gain effect of the SSHI and SECE is weakened. The experimental results of the medium coupling systems show that the BV-SSHI can obtain 247.2% harvested energy and 121.2% maximum harvested power compared with SEH. The BV-SSHI can achieve at least 142.4% harvested energy and 100.3% maximum harvested power compared with what SSHI and SECE can achieve.

Self-Propelled Pre-Biased Synchronous Charge Extraction Circuit for Triboelectric Nanogenerator

Triboelectric nanogenerators (TENGs) are suitable for harvesting ambient mechanical energy to increase the battery life of the Internet of Things (IoT) devices. Energy extraction circuits (EECs) are required as an interface between TENG and the onboard battery load to rectify and improve the energy transfer efficiency. Here, for the first time, a novel “self-propelled pre-biased synchronous charge extraction (spSCE)” EEC is presented with theoretical analysis as well as experimental results. The proposed EEC offers a universal plug-and-play solution for any TENG operating under any ambient vibration, due to its self-propelled switching feature. In addition, its inbuilt pre-biasing (precharging of TENG capacitor at the operation extremes) action enhances the net transduced energy from the mechanical source beyond the per-cycle energy limit for any non-pre-biasing EEC set by the existing synchronous charge extraction (SCE) circuit. Accounting for the energy costs of spSCE actions, our experiments validated 119.7% (resp., 163.7%) energy gain over the SCE circuit at a load of 5 V (resp., 15 V).

Design and Development of a Broadband Vibration Energy Harvester Suitable for Tractor Exhaust Cylinder Vibration

A large amount of vibration energy exists in the working environment of tractors. Therefore, the use of vibration energy harvesting technology to convert the vibration energy into electrical energy is a feasible way to supply power to low-power sensor equipment in agricultural machinery. Aiming at the problem in which the internal sensors of traditional tractors require built-in batteries or overlapping cables, this work proposes a broadband piezoelectric vibration energy harvester that could harvest the vibration energy from the tractor exhaust cylinder when the tractor is working. The vibration energy can be converted into electrical energy to power the air pressure sensor device. This experimental investigation shows that the energy harvester is composed of a folded piezoelectric energy harvester and a multi-source input synchronous electronic charge extraction circuit.The circuit has a high power density of 12,398 μW/(mm3·g2). Hence, it can convert vibration energy into a wide frequency range between 90-140 Hz and cause the air pressure sensor to operate.

A comprehensive analysis of piezoelectric energy harvesting from bridge vibrations

Piezoelectric energy harvesting from bridge vibrations has the potential to power wireless sensors used for bridge health monitoring. Often, it is necessary to store the harvested energy before it could be used to power the sensor intermittently. However, the behavior of the piezoelectric energy harvester (PEH) with nonlinear interface circuits for energy extraction and storage subject to realistic bridge vibrations has not been fully understood. This work performs a comprehensive analysis on the performance of the PEH subject to the measured railway bridge vibrations and compares the energy stored on a capacitor using four different interface circuits. Firstly, the dynamic characteristics of the railway bridge is analyzed. A cantilevered PEH is then designed and fabricated based on the dynamic characteristics of the bridge. Subsequently, four realistic energy extraction and storage interface circuits, namely, the standard energy harvesting (SEH), synchronized charge extraction (SCE), parallel synchronized switch harvesting on inductor (P-SSHI) and series SSHI (S-SSHI) circuits, are evaluated and compared when the PEH subject to the measured bridge vibrations. The influence of the storage capacitance and the 1st short-circuit natural frequency of the PEH on the stored energy with these four circuits is then discussed. An optimal storage capacitance exists in the systems based on SEH, P-SSHI and S-SSHI circuits. The system based on P-SSHI circuit has the highest efficiency on energy storage. This work provides a technical framework to develop the realistic energy harvesting and storage system for realization of self-powered bridge condition monitoring.

Synchronous Pre-biasing of Triboelectric Nanogenerator for Enhanced Energy Extraction

Triboelectric Nanogenerator (TENG) is a class of ambient mechanical energy harvesters used to augment the battery life of electronic devices such as sensors in implantables, wearables, and Internet of Things (IoT) applications. In this work, the fundamentals of pre-biasing (pre-charging) the TENG at the start of the operation cycle to enhance the per-cycle extracted energy is presented. The energy gain is mathematically formulated, and the optimum pre-biasing voltage (equivalently charge) is derived by analyzing the energy exchange between the mechanical and the electrical domain over a periodic cycle. Further, a novel Energy Extraction Circuit (EEC) termed as "Pre-biased Synchronous Charge Extraction (pSCE)" is introduced to 1) Realize synchronous pre-biasing of TENG using the load battery itself and 2) Achieve enhanced energy extraction from TENG. Energy output per-cycle is derived analytically for the pSCE circuit and compared to the state of the art Synchronous Charge Extraction (SCE) circuit. The experimental implementation is performed for the proposed pSCE circuit that shows a 6.65 fold gain over the Full Wave Rectifier (standard EEC) and 1.45 over the SCE circuit for a 5V battery load.

A Multistep Charge Extractions and Voltage Bias-Flip (MCEBF) Interface Circuit for Piezoelectric Energy Harvesting Enhancement

In piezoelectric energy harvesting (PEH), interface circuits using synchronous switch actions, including synchronized charge extraction (CE) and/or bias-flip (BF), can achieve much higher energy harvesting (EH) capability, compared with the standard energy harvesting (SEH) bridge rectifier. In this article, a multistep charge extraction and voltage bias-flip (MCEBF) interface circuit is proposed to further enhance the harvesting capability under weakly coupling conditions. The EH enhancement is realized by reducing the dissipation in CE with multiple CE actions and simultaneously enlarging the extracted energy with a BF action. MCEBF can also generate positive and negative voltage rails via buck-boost topology to supply power for double-rail devices. The optimal control method of MCEBF is theoretically derived. In our experiment, under constant deflection excitation, the best MCEBF case offers 487%, 95%, and 49% more harvested power, compared with SEH, synchronous electric charge extraction (SECE), and parallel synchronized switch harvesting on inductor (P-SSHI) interface circuits, respectively. MCEBF also keeps the benefit of load independence as SECE does under weakly coupling conditions.

Toward Nonlinear Galloping Energy Harvesting Interfaced With Different Power Extraction Circuits

While there has been a surge of study on nonlinear aeroelastic energy harvesting structures for enhanced wind power extraction, there is a gap in the literature on the integration of advanced power conditioning circuits with these mechanically sophisticated nonlinear structures. This article presents an investigation on the influence of different voltage processing interface circuits on the power generation performance in nonlinear galloping energy harvesting. Cubic hardening, cubic softening, and bistable configurations are studied. Their mechanical and electrical responses associated with the simple ac, standard dc, and synchronous charge extraction (SCE) circuits analyzed and compared. Results show that with the ac and standard dc circuits, the bistable and cubic hardening configurations are superior to the cubic softening configuration, generating comparably high power outputs with beneficially small displacements. The SCE circuit significantly boosts the power generation of the two monostable (cubic hardening and softening) harvester designs, but degrades the performance of the bistable design by trapping the oscillation within a single potential well over a large wind speed range. The findings form a baseline for future enhancement in the design of nonlinear aeroelastic wind power generators.

Investigations on energy harvesting systems incorporating mechanical and electrical nonlinearities to charge reusable batteries

This report analyzes the electromechanical coupling evident in vibration energy harvesting systems that charge reusable batteries. A model of a vibration energy harvesting system with far-from-equilibrium nonlinearities is considered for sake of capitalizing on high-energy forced vibrations. The piezoelectric structure is coupled with nonlinear interface circuits that leverage rectification and control stages to enhance power delivery to the battery. Three circuits, namely standard energy harvesting (SEH) circuit, parallel synchronized switching harvesting on inductor (P-SSHI) circuit, and synchronized charge extraction (SCE) are considered as interfaces between the nonlinear energy harvester and a battery. A simplified power calculation is numerically verified to accurately estimate the harvested power respectively delivered from three interface circuits to the battery. The investigations reveal that increasing required battery voltage may inhibit means to achieve high-energy vibrations and thus prevent battery charging. By a conservation of energy, it is shown that the phase lag between beam velocity and the base acceleration is the primary indicator of interference between dynamic energy flows in the electromechanical sub-systems. This research sheds light on the influences of energy storage components on the functioning of nonlinear vibration energy harvesting systems. Moreover, the principles uncovered for the inhibition of high-energy oscillation may guide future nonlinear energy harvesting system design to extract the best power out from the ambient vibration environments.

Binary-Like Topology Optimization of Piezoelectric Metamaterial Plate with Interface Circuits Using Extended Plane Wave Expansion Method

Piezoelectric metamaterial plate (PMP) is being investigated for structural vibration energy harvesting (SVEH), in which an interface circuit is often used. Thus, it is a challenge to perform bandgap optimization of such an elastic–electro–mechanical coupling system. This paper presents a binary-like topology optimization scheme by dividing the unit cell into identical pieces, where a {0, 1} matrix is optimized to indicate material distribution. Firstly, a unified motion equation is derived for the elastic plate and the piezoelectric patch, and an electromechanical coupling model is built for a self-powered synchronized charge extraction circuit. Then, an extended plane wave expansion method is presented to model the bandgap character of the PMP with interface circuits (PMPICs), and the numerical solution of the dispersion curves is derived based on the Bloch theorem. Next, an extended genetic algorithm is applied for the topology optimization of the PMPIC. In the end, numerical and finite element simulations are performed to validate the proposed method. The results demonstrate that both the structure and the circuit can be optimized simultaneously to obtain the maximum first-order bandgap at a given central frequency. Therefore, the proposed method should provide an effective solution for the topology optimization of a PMPIC for broadband SVEH.

Transient response of a nonlinear energy sink based piezoelectric vibration energy harvester coupled to a synchronized charge extraction interface

Integration of a piezoelectric transducer with a nonlinear energy sink (NES) has been realized for both vibration mitigation and broadband energy harvesting. However, to ensure that a harvester can generate power in a truly broadband manner, the impedance matching issue of the interface circuit should be addressed. The synchronized charge extraction (SCE) is one technology that has been proved to be able to address this issue for linear energy harvesters. This work intends to investigate the transient response of an NES-based piezoelectric vibration energy harvesting system interfaced with an SCE interface (NESVEH-SCE). The nonlinear normal mode of such an electromechanically coupled system is analyzed on the basis of the equivalent impedance method and complexification-averaging method. The frequency-energy plots are depicted and verified by wavelet analysis. The effects of electromechanical coupling strength, electrical load in the SCE interface and initial input energy level on the performance of the proposed system are discussed by using the circuit simulation tool. Finally, experiments are performed to verify the consequences obtained from the theoretical and numerical methods, and demonstrate that the energy harvested during the transient response of the NESVEH-SCE system is independent of the electrical load in the SCE interface.

Analysis of Piezoelectric Energy Harvesting Interface Circuit Applied to Automobile Engine Vibration

In order to realize the continuous power supply for the vibration fault monitoring system of automobile engine, aiming at the low efficiency and instability of the existing piezoelectric full bridge rectifier energy collection circuit, this paper proposes a circuit scheme based on synchronous charge extraction. The scheme can provide circuit collection efficiency, and analyze the power of the circuit by impedance analysis. Finally, the experiment shows that the theoretical analysis is consistent with the experimental results. And the synchronous electrical charge extraction circuit can harvest power up to 1.3mW under low frequency conditions, which is higher than 0.5mW collected by the full-bridge rectifier circuit under the same conditions. The harvested energy meets the power requirements of automotive sensors and microcontrollers.

Modeling, analysis and comparison of four charging interface circuits for piezoelectric energy harvesting

Four interface circuits have been widely studied in piezoelectric energy harvesting over the last two decades, namely, the standard energy harvesting (SEH) circuit, synchronized charge extraction (SCE) circuit, parallel synchronized switch harvesting on inductor (P-SSHI) circuit and series synchronized switch harvesting on inductor (S-SSHI) circuit. However, the abilities of these four circuits to charge storage capacitors are yet to be understood. This work focuses on the modeling and comparison of the charging process of these four circuits. First, the solutions of the voltage variations on the storage capacitors during charging process in each half-cycle are derived. Subsequently, the equivalent circuit model of the harvester interfaced with SEH and self-powered SCE, P-SSHI and S-SSHI circuits are implemented and simulated to validate the theoretical results. In the evaluation of the four circuits, different electromechanical coupling conditions of the PEH have been considered. The influence of the storage capacitance on charging performance are investigated. It is shown that for the SEH, P-SSHI or S-SSHI circuit, an optimal storage capacitor exists to maximize the accumulated energy and it varies with coupling condition. For a PEH with weak coupling, the P-SSHI circuits is suitable for energy charging. For the medium and strong coupling conditions, the SEH and S-SSHI circuits are more efficient as compared to the P-SSHI and SCE circuits.

Vibration energy harvesting based on a piezoelectric nonlinear energy sink with synchronized charge extraction interface circuit

Nonlinear energy sink (NES) conventionally designed for vibration control has been recently explored for energy harvesting purpose. To simplify the analysis, a pure resistive load is usually used in the evaluation of the performance of NES-based energy harvesting systems. This paper investigates the performance of an NES-based energy harvesting system interfaced to a synchronized charge extraction (SCE) circuit (EHNES-SCE). For the ease of analysis, the SCE interface circuit is simplified by the equivalent impedance method. An equivalent circuit model for system-level simulation of the EHNES-SCE system is also established to confirm the feasibility of using the simplified SCE circuit. Subsequently, with the simplified SCE circuit, approximate analytical solutions of the EHNES-SCE system are derived using the harmonic balance method and the performance of the EHNES-SCE system under harmonic excitation is investigated. With the established modelling and simulation tools, the influences of electrical load and electromechanical coupling on the performance of the EHNES-SCE system are revealed. Finally, experimental results are presented to confirm the main findings from the theory and simulation and reveal that the EHNES-SCE system is able to harvest energy in a wide frequency range, regardless of the load resistance in the SCE circuit.

Maximum Obtainable Energy Harvesting Power from Galloping-Based Piezoelectrics

In this paper, the maximum obtainable energy from a galloping cantilever beam is found. The system consists of a bluff body in front of wind which was mounted on a cantilever beam and supported by piezoelectric sheets. Wind energy caused the transverse vibration of the beam and the mechanical energy of vibration is transferred to electrical charge by use of piezoelectric transducer. The nonlinear motion of the Euler–Bernoulli beam and conservation of electrical energy is modeled by lumped ordinary differential equations. The wind forces on the bluff body are modeled by quasisteady aeroelasticity approximation where the fluid and solid corresponding dynamics are disconnected in time scales. The linearized motion of beam is limited by its yield stress which causes to find a limit on energy harvesting of the system. The theory founded is used to check the validity of previous results of researchers for the effect of wind speed, tip cross-section geometry, and electrical load resistance on onset speed to galloping, tip displacement, and harvested power. Finally, maximum obtainable average power in a standard RC circuit as a function of deflection limit and synchronized charge extraction is obtained.

Extensible Multi-Input Synchronous Electronic Charge Extraction Circuit Based on Triple Stack Resonance for Piezoelectric and Thermoelectric Energy Harvesting

At present, research on interface circuits for environmental energy harvesting is mainly carried out around a single transducer. However, rich ambient energy sources can be harvested with multiple transducers. Hence, in this article, extensible multi-input synchronous electronic charge extraction (EMI-SECE) interface circuit based on triple-stack LC resonance for piezoelectric and thermoelectric energy harvesting is proposed. proposed EMI-SECE interface circuit can simultaneously extract energy from multiple piezoelectric transducers (PZTs) and thermoelectric generators when the peak open-circuit voltage of the PZTs is detected by the passive peak detectors. Theoretical analysis and experiments verify the effectiveness of the circuit. The experimental results show that the proposed EMI-SECE circuit can harvest energy from two PZTs with any phase difference (0-2π) based on single inductor. In addition, the circuit can harvest thermoelectric energy at an open-circuit voltage as low as 20 mV, and the maximum harvesting efficiency can be reached 85.7% at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> = 200 mV.

Elastic-electro-mechanical modeling and analysis of piezoelectric metamaterial plate with a self-powered synchronized charge extraction circuit for vibration energy harvesting

Structural vibrations usually exist in the form of low-frequency and broadband elastic waves, so cantilever-like harvesters are not appropriate due to space limitations and high quality factor. Piezoelectric metamaterial plate with local resonators (PMP-LR) has been explored to overcome it. However, how to model and analyze the whole energy harvesting system is still a challenge. In this paper, a self-powered synchronized charge extraction circuit is presented and connected to the PMP-LP as the interface circuit. An elastic-electro-mechanical model is built based on the Kirchhoff plate theory and equivalent impedance method, where equivalent impedance of the self-powered synchronized charge extraction circuit is first derived. Then the elastic-electro-mechanical model is numerically solved by using the Bloch theorem and wave finite element method. By numerical simulations, it is found that the synchronized charge extraction circuit has few effects on vibration bandgaps of the PMP-LR. While by inserting an inductor (Lr) parallel with the clamped capacitor (Cp) of the piezoelectric patch, we can see that a new dispersion curve is induced by the Lr-Cp electrical resonance and the inductor is beneficial for low-frequency and broadband vibration energy harvesting. In particular, the inductor can greatly improve the harvesting performance when the resonant frequency is equal to the excitation frequency. In the end, experiments are done and the results are consistent with the numerical ones. Excitingly, the output voltage amplitude of the piezoelectric patch is enlarged about 200% after using the resonant inductor.

Large-bandwidth piezoelectric energy harvesting with frequency-tuning synchronized electric charge extraction

This paper reports, for the first time, experimental evidence of the effectiveness of the frequency-tuning synchronized electrical charge extraction technique (FTSECE) with a strongly-coupled generator. The ratio between the system bandwidth (7 Hz) and the natural bandwidth of the transducer (0.688 Hz) is 1017 %, surpassing previous demonstrations of synchronized charge extraction methods by a large extent. We prove that the bandwidth of the FTSECE system is only limited by the unideal characteristics of the circuit components and generator. This is a major advantage of FTSECE as opposed to other competitive methods where the bandwidth is intrinsically mathematically limited, even in the hypothetical presence of ideal components. We also propose a new circuit for the implementation of FTSECE, which allows the piezoelectric generator to be connected to the same ground as the control circuit. Our experimental setup based on the combination of a strongly-coupled piezoelectric generator and a FTSECE architecture allows operation at a maximum power plateau on a +/-3.5 % interval around the resonance frequency. The resulting full width at half maximum (FWHM) is +/-10 % around the resonance frequency, which corresponds to +200 % compared to most up-to-date architectures designed for bandwidth enhancement, with the advantage of suppressing local minima in the power responses.