Capacitor Charging Research Articles

Loss Modulated Deadbeat Control for Grid Connected Inverter System

Deadbeat controllers are commonly employed in grid connected inverter systems for their fast transient response. In this paper, a loss modulated deadbeat current control (DCC) is proposed for a grid connected inverter system. This control calculates the required modulation signal by considering the losses in the system at every switching cycle. The proposed method tracks the reference current with negligible error. The loss component used in the control method eliminates the effect of sensing and computational time delay and adapts to variation in system parameter. The proposed DCC is extended for deadbeat based direct power control (DDPC) without employing inner current control loop. Further, a modified DDPC is presented to eliminate the delay of one switching cycle which is inherently present for the grid current in DCC. The proposed control concepts are realized on a multi-source fed switched capacitor based multilevel inverter. The topology considered features more number of voltage levels with less component count, high gain, self capacitor charge balancing and increased source utilization. The steady-state and transient behaviour of the control methods are verified in simulation and experimental studies for a power rating of 500 W under various system conditions. The proposed algorithms are able to track the reference signals with fast transient response and negligible steady-state error.

Reconfigurable negative bit line collapsed supply write-assist for 9T-ST static random access memory cell

<span lang="EN-US">This paper presents a reconfigurable negative bit line collapsed supply (RNBLCS) write driver circuit for the 9T Schmitt trigger-based static random-access memory (SRAM) cell (9T-ST), significantly improving write performance for real-time memory applications. In deep sub-micron technology, increasing device parameter deviations significantly reduce SRAM cells' write-ability. The proposed RNBLCS write-assist driver for 9T-ST SRAM cell has 0.84×, 0.48×, 0.27× optimized write access delay and 1.05×, 1.08×, 1.19× improvement in write static noise margin (WSNM), 1.05×, 1.13×, and 1.39× improvement in write margin (WM), 0.96×, 0.89× and 0.72× minimum write trip-point (WTP) from transient-negative bit line (Tran-NBL), capacitive charge sharing (CCS), and conventional write circuits respectively. The proposed RNBLCS is functionally verified using a synopsys custom compiler with a 16 nm BSIM4 model card for bulk complementary metal-oxide semiconductor (</span><span lang="EN-US">CMOS).</span>

A Highly Efficient E-Band CMOS Frequency Tripler With a Third Harmonic Boosting Technique

An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$</tex-math> </inline-formula> -band CMOS frequency tripler with a third harmonic boosting technique (THBT) is presented to simultaneously improve the conversion efficiency (CE) and output power. The THBT is theoretically analyzed for increasing a conversion gain (CG) and reducing the design complexity of the CMOS tripler. The gain and stability of the buffer amplifier in the proposed tripler are improved by using the capacitive charge neutralization technique with an insensitive variation of the capacitance. The differential configuration and transformer-based matching networks in the tripler suppress the fundamental and even-order harmonic signals without an additional filter. The proposed tripler, fabricated using 65-nm CMOS technology, showed a maximum CE of 10.89% for an input power of 6.5 dBm at 71.1 GHz. The maximum output power and CG were measured to be 9.9 dBm and 4 dB, respectively.

Redox-Active Benzodithiophene-4,8-dione-Based conjugated microporous polymers for High-Performance faradaic supercapacitor energy storage

Conjugated microporous polymers (CMPs) are attractive materials due to their microporous architecture, modifiable physical–chemical characteristics, and extended π-conjugated structures. However, their low electronic conductivity limits the development of CMPs with high specific capacitance and excellent charge–discharge stability for supercapacitor energy storage. Furthermore, the redox-active moieties in CMPs for innovative electrode materials are still restricted. Herein, for the first time, two novel redox-active benzo[1,2-b:4,5-b']dithiophene-4,8-dione-based conjugated microporous polymers (DBTh-CMPs), namely, DBTh-TPA and DBTh-TPT CMPs, were prepared through the one-pot Suzuki coupling polymerization of 2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-dione with triboronic-pinacolates. The DBTh-CMPs exhibited outstanding thermal stabilities (Td10: approximately 608.4 °C; char yield: approximately 71.76%) and surface areas (around 551 m2/g). Interestingly, incorporating redox-active DBTh structures into the backbone of the CMPs resulted in promising conductivity, exceptional faradaic energy storage, and efficient charge transfer. The DBTh-CMPs displayed an exceptional three-electrode capacitance of 1823F g−1 at a current density of 0.5 A g−1 with superior stability of 81.75% over 10,000 cycles; such a value is the largest specific capacity documented via the CMP to date. The two-electrode symmetric supercapacitor device by DBTh-TPT CMP showed a specific capacitance of 609F g−1 and a maximum energy density of 84.5 W h kg−1 operating at a power density equal to 500 W kg−1 and a potential of 1.0 V. The present research supplies a viable strategy for developing electrochemical gadgets and future-oriented supercapacitors.

Induced-charge membrane capacitive deionization enables high-efficient desalination with polarized porous electrodes

Exposure of a conducting porous material to an electric field in electrolytes induces an electric dipole, which results in capacitive charging of cations and anions at opposite poles. In this letter, we investigate a novel desalination method using this induced-charge capacitive deionization (ICCDI). To do this, we devise a microscale ICCDI platform that can visualize in situ ion concentrations, pH shifts, and fluid flows, and study ion transport dynamics and desalination performances compared to conventional CDI with unipolar / bipolar connections. Similar ion concentration and fluid flow characteristics were observed in Ohmic, limiting, and over-limiting regimes, but variations in desalination performance trends were noted based on the number of stacks. In a single cell, ICCDI generates a higher electric field at the opposite poles of porous electrodes than simple conducted electrodes in CDIs with unipolar/bipolar connections, leading to superior salt removal and/or lower ionic current at a given applied voltage. This marks a clear contrast from CDI with bipolar connection, which lacks any advantage over CDI with unipolar connection in a single cell. These metrics of ICCDI however deteriorated as the stack number increased, likely due to short-circuiting between the dipoles. As a result, ICCDI in current form shows higher desalination efficient than conventional CDIs with low stack numbers (< 6), so we offer the scale-up module by repeating 4-stack ICCDI units. Our study enhances comprehension of ion transport dynamics and desalination performance in ICCDI, and the results could aid in the development of ICCDI for energy/cost-efficient desalination.

Hybrid approach based combined allocation of electric vehicle charging stations and capacitors in distribution systems

This manuscript proposes a hybrid EOO-QNN method for the combined allocation of electric vehicle charging stations (EVCS) and capacitors in the distribution systems (DS). The proposed hybrid approach is combined with Eurasian Oystercatcher Optimiser (EOO) and Quantum Neural Network (QNN). Hence it is known as an EOO-QNN approach. The primary objective of EOO-QNN algorithm is to control the capacitors to maintain the voltage-profile, increase the net gain and minimize active power loss. The EOO approach is utilized to produce solutions for the power loss problems while improving the dependability of distribution network, and the QNN is employed to forecast the converter's ideal control signal. By then, the proposed method is executed in MATLAB and is compared with other existing methods. The EOO-QNN method shows better results in all approaches, like Particle swarm optimization (PSO), Wild horse optimizer (WHO), and Scalp Swarm Algorithm (SSA). From the simulation, it accomplishes that the voltage of EOO-QNN approach is high compared to existing techniques. From the simulation analysis, the proposed method based high voltage 500 V is high compared to other existing methods. From the result, it proven that the EOO-QNN method provides higher voltage compared to existing methods.

Perovskite V–NaNbO3 embedded PDMS composite film-based robust hybrid nanogenerator for efficient mechanical energy harvesting

Recently, perovskites are attracting great attention in the field of energy harvesting through triboelectric nanogenerators as a promising technology owing to their easy synthesis process, ferroelectric/dielectric nature, and low toxicity. Herein, we proposed the vanadium-doped sodium niobate (NaNbO3) (V–NaNbO; VNNb)/polydimethylsiloxane (PDMS) composite film-based hybrid nanogenerators (HNGs) for mechanical/biomechanical energy harvesting. Initially, the perovskite NNb and VNNb microparticles (MPs) were synthesized and mixed inside PDMS to form a negative triboelectric film. The aluminum film was used as a positive triboelectric material and to support the waste-to-wealth concept, discarded plastic was used as a substrate material. Various HNGs were assembled and operated in a contact-separation mode and a comparative study of variation in electrical output depending on the type/amount of filler particles was thoroughly investigated. The VNNb/PDMS-based HNG produced an enhanced electrical output of ∼200 V, ∼5.7 μA, 4.8 W/m2 as compared to the bare PDMS- and NNb/PDMS-based HNGs. The fabricated HNG was robust and generated a highly stable electrical output that was further utilized to charge capacitors and power small electronics. Moreover, owing to the flexible nature and highly efficient electrical output of the HNG, it was successfully demonstrated as a biomechanical energy harvester.

Optimization of electromagnetic-triboelectric wind energy harvester based on coaxial reversed mechanism with tip discharge

In recent years, the development of triboelectric-electromagnetic composite energy harvesters has revolutionized low-power urban devices by providing a cost-effective and high-output energy solution. However, most triboelectric nanogenerators (TENGs) have limited current output in the μA range, restricting their widespread application. Additionally, existing electromagnetic structures lack compactness and portability. To address these challenges, this paper proposes a compact triboelectric-electromagnetic composite wind energy harvester based on a coaxial reversing mechanism and tip discharge. It achieves gas ionization and increases the TENG's output current by utilizing TENG charge accumulation during rotation through a sidewall tip-copper structure. Compared to conventional TENGs, this harvester elevates the current from the μA level to the mA level. Moreover, it improves the output performance of the small volume electromagnetic generator (EMG) structure through the synchronous reversal of the magnet and coil at the same wind speed using two coaxial reversing propellers, intensifying the magnetic flux variation. Notably, the EMG structure outperforms a single rotating coil or magnet, achieving a remarkable 12% increase in output performance. At average urban wind speeds, this wind energy harvester can charge capacitors of 33 μF, 100 μF, and 220 μF to 2.5 V in 1.6 s, 2 s, and 3.6 s. Furthermore, it can power over 500 small LEDs and support the operation of temperature and humidity sensors. With its efficient wind energy harvesting technology, the proposed harvester holds great promise for self-powered Internet of Things (IoT) applications.

Metal-Organic Framework Based Triboelectric Nanogenerator for a Self-Powered Methanol Sensor with High Sensitivity and Selectivity.

Triboelectric nanogenerators have shown great potential in the area of self-powered gas sensors in the past decade. In this paper, we developed a triboelectric nanogenerator (TENG) based on spiky structured ZIF-8@ZnO, which can harvest energy with high efficiency and act as a self-powered methanol sensor. The open-circuit voltage and short-circuit current generated by a ZIF-8@ZnO-based TENG is 58 V and 10 μA, achieving 2.4 times and 3.3 times enhancement compared to ZnO-based TENGs. The TENG can charge capacitors fast and light up at least 40 LEDs. ZIF-8@ZnO-based TENGs show good sensitivity and selectivity to methanol gas at room temperature due to the porous structure provided by ZIF-8 and the heterostructure of ZIF-8@ZnO. The response of ZIF-8@ZnO-based TENG to methanol reaches 30.35% at 100 ppm with excellent response (∼5.9 s) and recovery time (∼2.2 s). This work demonstrates the application of MOF-modified metal oxide semiconductors based on a self-powered gas sensor and proposes a promising solution to enhance the output performance and sensing properties of TENGs based on metal oxide semiconductors.

A voltage lift‐based high‐gain DC‐DC converter with low input current ripple

AbstractThe switched‐inductor‐based voltage lift converters offer high voltage gain. However, their input current has step changes due to switched‐inductor configuration and is peaky due to the voltage lift capacitor charging current. This article proposes a new high‐gain DC‐DC converter where an additional boost converter cell is incorporated in a conventional voltage lift boost converter to charge the voltage lift capacitor with a constant current, avoiding a peaky charging current from the supply. The operating principle of the proposed converter demands phase‐shifted switching signals to achieve high voltage gain and reduce ripple in the input current. High‐gain, continuous input current, positive output voltage, common ground between input and output ports, and low voltage stress on active switches are the major characteristics of the proposed converter. The operating principle, steady‐state analysis, and control design have been discussed in detail. A 200 W, 30 V/300 V, and 50 kHz laboratory prototype is developed to validate the operation of the proposed converter.

A biocompatible and antibacterial all-textile structured triboelectric nanogenerator for self-powered tactile sensing

With the rapid development of cutting-edge technologies, self-powered breathable wearable electronic textiles have received significant attention because of portable and convenient power sources. In this work, a biocompatible and antibacterial all-textile structured triboelectric nanogenerator was designed for self-powered tactile sensing, constructed by the MXene doped PVDF (P/M) nanofibers and the antibacterial Ag nanoparticles modified nylon 6,6 (Ag@nylon 6/6) nanofibers as the triboelectric negative and positive materials, respectively. The effect of MXenes in PVDF nanofibers for its mutual interaction, surface potential, breathability, tensile strength, biocompatibility, and triboelectric performance was evaluated thoroughly through experimental and theoretical investigations. As developed P/M nanofiber film was paired with tribopositive Ag@nylon 6/6 nanofibers to fabricate the TENG, exhibiting a high output voltage of 362 V and an output current of 38.5 μA. The triboelectric harvesting properties were further demonstrated by capacitor charging and the operation of low power devices such as the clock, 95 commercial LEDs. In addition, a self-powered tactile sensor based on the Ag@nylon 6,6 and P/M fibrous membranes realizes ultrasensitive motion and pulse detection from different arteries, and the fabricated tactile sensor array shows a great potential in the application of smart wearable keyboard as well as high-resolution tactile mapping.

Piezoelectric Transformer-Based High-Voltage Pulse Generator Using Wide-Bandgap Semiconductors for Medical Electroporation Therapy.

In this paper, a new application of Piezoelectric Transformer (PT)-based power converters to generate high-voltage (HV) bipolar pulses for medical electroporation therapy is proposed. In particular, PT-based power conversion is investigated as an alternative to magnetics-based approaches of generating HV from a relatively low-voltage (LV)input source for application in electroporation therapy. The detailed PT-based system design and selection of wide bandgap semiconductor switches such as GaN FETs, high-voltage SiC diodes and SiC MOSFETs, as well as simulation results to demonstrate proof-of-concept using LTSpice are presented. Preliminary experimental results of the PT-based capacitor charger are shown, and work is ongoing to develop a complete hardware prototype of the proposed HV pulse generator.

All-Round Enhancement in Zn-Ion Storage Enabled by Solvent-Guided Lewis Acid-Base Self-Assembly of Heterodiatomic Carbon Nanotubes.

Designing zincophilic and stable carbon nanostructures is critical for Zn-ion storage with superior capacitive activity and durability. Here, we report solvent-guided Lewis acid-base self-assembly to customize heterodiatomic carbon nanotubes, triggered by the reaction between iron chloride and α,α'-dichloro-p-xylene. In this strategy, modulating the solvent-precursor interaction through the optimization of solvent formula stimulates differential thermodynamic solubilization, growth kinetics, and self-assembly behaviors of Lewis polymeric chains, thereby accurately tailoring carbon nanoarchitectures to evoke superior Zn-ion storage. Featured with open hollow interiors and porous tubular topologies, the solvent-optimized carbon nanotubes allow low ion-migration barriers to deeply access the built-in zincophilic sites by high-kinetics physical Zn2+/CF3SO3- adsorption and robust chemical Zn2+ redox with pyridine/carbonyl motifs, which maximizes the spatial capacitive charge storage density. Thus, as-designed heterodiatomic carbon nanotube cathodes provide all-round improvement in Zn-ion storage, including a high energy density (140 W h kg-1), a large current activity (100 A g-1), and an exceptional long-term cyclability (100,000 cycles at 50 A g-1). This study provides appealing insights into the solvent-mediated Lewis pair self-assembly design of nanostructured carbons toward advanced Zn-ion energy storage.

Vortex-induced vibration triboelectric nanogenerator for energy harvesting from low-frequency water flow

The hydrokinetic energy from wind and water flow widely exists in nature. Even though previous studies have proposed various design architectures using both piezoelectric and triboelectric effects to capture the kinetic energy of the wind, they can hardly be applied into low-speed water environment. In this paper, we propose a vortex-induced vibration triboelectric nanogenerator (VIV-TENG) to scavenge energy from low-speed water. The VIV-TENG is mainly composed of a cylinder and a rail with two nanogenerators. The vortex is aroused by the cylinder and the vibration is amplified by the cantilever beam. We introduce a correction factor into the classical vortex-induced vibration coupling model to investigate the vortex shedding of the device. The finite element analysis is conducted to validate the theoretical model and is used to interpret the vortex resonance of the VIV-TENG. Besides, we experimentally demonstrate that the VIV-TENG achieves a maximum open-circuit voltage output of 174 V and a maximum power output of 2.5 mW at 1 MΩ in the condition of vortex resonance. The VIV-TENG also shows the ability to charge capacitors. This study provides a new approach for harvesting energy from low-speed water flow using the triboelectric effect.

A Self-Capacitance Proximity E-Skin With Long-Range Sensibility for Robotic Arm Environment Perception

Proximity sensing is a major requirement for intelligent robots and robotic arms to ensure safety and closed-loop control in human–robot interactions. E-skins have received increasing attention because of their ease of arraying and installation. However, problems, such as insufficient sensing distance and inaccurate distance prediction, still exist. To solve these problems, we propose a self-capacitance-based long-range proximity sensing e-skin. First, two electrode shape classifications, external edge and internal holes, were analyzed and optimized in COMSOL to explore the variation trends of charge distribution and capacitance proximity characteristics. Then, based on the self-capacitance proximity theory, the parameters of the fitting function for the actual capacitance–distance curves for the four electrodes were solved using the planning solution method. The results show that the sensor has a good dynamic response, a long proximity sensing range (10.9 cm), high distance estimation accuracy (σ = 0.45), and good repeatability (>2 h). Finally, we integrate the sensor array with the end joint of the robotic arm to complete a sorting task. A closed-loop control demonstration of safe obstacle avoidance and deceleration was achieved, thereby demonstrating the great potential of e-skin for future human–machine collaboration scenarios.

Design and performance of a micro-scale detonation train with a built-in pyrotechnic MEMS-based safety and arming device

To improve the equipment miniaturization and reliability of weapons and ammunition systems, this study designs a micro-scale detonation train (MDT) with a built-in pyrotechnic microelectromechanical system (MEMS)-based safety and arming (S&A) device, which consists of an energetic semiconductor bridge (ESCB) detonator, and a S&A device with built-in isolation mechanisms, and a micro-detonation train. Furthermore, this study investigates the effects of the slider thickness, the spring beams’ thickness, and the positioning beam type on the security of the S&A device using the Finite Element Dynamics software and verifies the function of the MDT through experiments of capacitive charge and discharge ignition. As indicated by the results, an encouraging arming function can be achieved under a slider thickness of 1.0 ​mm and a positioning beam type of PB, while the spring beam thickness is less relevant. Additionally, the results show that the arming function of the MDT can be completed in 0.6 ​ms.

Design and Performance Analysis of Negative Capacitance Effect in the Charge Plasma-Based Junction-Less Vertical TFET Structure

In this paper, a negative capacitance (NC) effect in series with normal oxide capacitance is first time introduced to design negative capacitance charge plasma-based junction less vertical TFET structure (NC-CP-JL-VTFET). The introduced negative capacitance enhances the overall gate capacitance and hence gate capacitive coupling and thus renders high current capabilities with reduced sub-threshold slope and threshold voltage. With the use of negative capacitance along with oxide capacitance, it has been seen that the same drain current is achieved at lower gate voltage as compared to without use of negative capacitance and since the voltage scaling is done considerably, the dynamic power dissipation in circuit application can be reduced significantly. To generate the negative capacitance during the device operation; ferroelectric material [Formula: see text](VDF-TrFE) poly(vinylidene fluoride-trifluoro ethylene) is used in stack with SiO2 gate oxide. Various performance parameters of the designed structure such as electron–hole concentration in the tunneling junction, electric field, surface potential, electron–hole quasi-Fermi variation, and drain current variation are investigated and compared with the results of without considering the ferroelectric material in the gate oxide. The variation of the ferroelectric thickness on the device performance is also investigated. The investigation exhibits significant improvement in the drain current and in the other parameters as well. These improvements are seen because of higher capacitive coupling and these effects are further responsible for more energy band bending which in turn govern high electron tunneling. Due to the existence of negative capacitance, the peak value of the electric field gets doubled while the surface potential increases 44% from the normal structure.

General Capacitance Upper Limit and Its Manifestation for Aqueous Graphene Interfaces

Double-layer capacitance (Cdl) is essential for chemical and biological sensors and capacitor applications. The correct formula for Cdl is a controversial subject for practically useful graphene interfaces with water, aqueous solutions, and other liquids. We have developed a model of Cdl, considering the capacitance of a charge accumulation layer (Cca) and capacitance (Ce) of a capacitance-limiting edge region with negligible electric susceptibility and conductivity between this layer and the capacitor electrode. These capacitances are connected in series, and Cdl can be obtained from 1/Cdl = 1/Cca + 1/Ce. In the case of aqueous graphene interfaces, this model predicts that Cdl is significantly affected by Ce. We have studied the graphene/water interface capacitance by low-frequency impedance spectroscopy. Comparison of the model predictions with the experimental results implies that the distance from charge carriers in graphene to the nearest molecular charges at the interface can be ~(0.05–0.1)nm and is about a typical length of the carbon-hydrogen bond. Generalization of this model, assuming that such an edge region between a conducting electrode and a charge accumulating region is intrinsic for a broad range of non-faradaic capacitors and cannot be thinner than an atomic size of ~0.05 nm, predicts a general capacitance upper limit of ~18 μF/cm2.

Design and Comparative Analysis of an Ultra-Highly Efficient, Compact Half-Bridge LLC Resonant GaN Converter for Low-Power Applications

For low-power applications, this paper presents the development and design of a compact and ultra-highly efficient half-bridge LLC resonant converter. By using Galium Nitride (GaN) devices and high-efficient magnetics, the efficiency and power density of resonant converters can be improved. Compared to Silicon MOSFETs, GaN high-electron-mobility transistors (GaN HEMT) have a lower output capacitance and gate charge, resulting in lower driving loss and shorter dead times. Consequently, the proposed LLC converter based on GaN devices has excellent performance characteristics such as ultra-high efficiency, low switching losses, compact size, high voltage endurance, high operating temperature and high operating frequency. Furthermore, the proposed resonant converter features soft switching properties that ensure that the switches and diodes on the primary side are always switched at zero voltage and current. By doing so, LLC resonant converter switching losses are significantly reduced by up to 3.1%, and an overall efficiency of 98.5% is achieved. The LLC resonant converter design with GaN HEMT has great advantages over Si MOSFET solution regarding efficiency, overall losses, switching loose and power factor correction. A 240 W, 240 V to 60 V half-bridge GaN HEMT LLC resonant converter is simulated with a switching frequency of 75 KHz, along with the comparative analysis of the Si metal oxide semiconductor field effect transistor (MOSFET) solution. Moreover, the design and analysis of highly efficient magnetics with a power factor of 0.99 at full load is presented. A 240-Watt single stage LED driver with power factor correction is also designed to verify and compare the performance of proposed LLC resonant converter.

First principles study on copper passivated armchair graphene nanoribbon for a supercapacitor electrode material

Density functional theory was employed to calculate the electronic properties of three armchair graphene nanoribbon systems (AGNR), namely, hydrogen-passivated (H-AGNR-H), passivated with copper and hydrogen on opposite sides (Cu-AGNR-H), and passivated on both sides with copper (Cu-AGNR-Cu). The calculations were carried out using 1 × 20×1 and 1 × 100×1 k-points for the self consistent field (scf) and non-self consistent field (nscf) calculations, respectively. Based on the formation energies, all three systems were structurally stable when compared to other nanoribbon systems. For the copper-passivated system, Cu–AGNR-H (-0.54 eV) was found to be more stable than Cu-AGNR-Cu (-0.28 eV). Phonon dispersion calculations were also conducted showing that Cu-AGNR-H is more stable dynamically than Cu-AGNR-Cu. The quantum capacitance and the total surface charge were computed to quantify the material's properties as a supercapacitor. Cu-AGNR-Cu showed superior quantum capacitance and surface charge values, while Cu-AGNR-H showed vast improvements when compared to H-AGNR-H. With an ideal structural stability, vibrational stability, quantum capacitance, and surface charge values, the Cu-AGNR-H system was the most viable material for electrodes among the three nanoribbon systems.