Improved Output Voltage Research Articles

Design and Implementation of Modular Multi-Level Converter Based HVDC System for Grid Connection

This paper examines Modular Multilevel Converters (MMC) for harnessing power from offshore wind farms. MMCs use many simple Voltage Source Converter (VSC) submodules, enabling high-voltage and high-power applications. They offer faster response times and lower harmonic distortion than traditional two-level VSCs. The paper addresses modelling challenges due to numerous switching devices and discusses the development of Cascaded Two-Level (CTL) converters, which improve output voltage quality. Overall, the study highlights advancements in MMC technology that enhance HVDC transmission capabilities.

Quasi-Resonant Fly-Buck Converter With Active Switching for Improved Output Voltage Boosting and Regulation

Quasi-Resonant Fly-Buck Converter With Active Switching for Improved Output Voltage Boosting and Regulation

Core-shell architecture and channel suppression: unleashing the potential of SC_RCS_DGJLFET

In this investigation, a suppressed channel-rectangular core–shell double gate junctionless field effect transistor (SC_RCS_DGJLFET) is simulated to enhance the junctionless device’s performance. This study leverages a core–shell architecture and channel suppression technique to improve the gate controllability over the channel region which helps in substantial depletion of the shells in the OFF state of the device. When compared to conventional double gate JLFETs (C_DGJLFET) and rectangular core–shell double gate JLFETs (RCS_DGJLFET), the performance of the SC_RCS_DGJLFET is superior in terms of IOFF, ION/IOFF ratio, DIBL and subthreshold slope (SS). The SC_RCS_DGJLFET achieves an ultra-low IOFF of 7.033 × 10−16 A, indicating a low leakage current with an impressive ION/IOFF = 5.092 × 1011 . Other performance parameters such as subthreshold slope and DIBL has also been improved for the SC_RCS_DGJLFET device. Subthreshold slope has been decresesd by 4.76% whereas the DIBL decreased by 33.82% when compared to existing RCS_DGJLFET. Additionally, to analyze the effect of doping on the device performance, the core doping in SC_RCS_DGJLFET is varied for fixed shell doping. The study found that fixing core doping to an appropriate value is a crucial parameter to achieve good device performance. The impact of variation of oxide extension towards the source and drain LextS/LextD in SC_RCS_DGJLFET is also studied for the first time in the core–shell architecture which has further improved the device’s performance. Finally, a CMOS inverter is designed using the proposed device that provides valuable insights into its suitability for digital circuit applications and verifies its performance benefits compared to existing transistor technologies. The SC_RCS_DGJLFET based CMOS inverter shows a sharp transition in voltage transfer characteristics (VTC), indicating fast switching speed and precise signal processing capabilities when compared to a CMOS inverter based on a conventional double gate junctionless field effect transistor (C_DGJLFET). Moreover, the transient characteristics of the SC_RCS_DGJLFET based CMOS inverter exhibit an improved output voltage swing, suggesting enhanced dynamic behaviour and stability during logic state transitions.

Wafer-Scale GaN-Si(100) Monolithic Heterogeneous Integration Inverters With Improved Output Voltage Swing and Fast Switching Capability by Transfer Printing and Self-Aligned Etching Technology

Wafer-Scale GaN-Si(100) Monolithic Heterogeneous Integration Inverters With Improved Output Voltage Swing and Fast Switching Capability by Transfer Printing and Self-Aligned Etching Technology

Boron-doped reduced graphene oxide as an efficient cathode in microbial fuel cells for biological toxicity detection

Electrodes with superior stability and sensitivity are highly desirable in advancing the toxicity detection efficiency of microbial fuel cells (MFCs). Herein, boron-doped reduced graphene oxide (B-rGO) was synthesized and utilized as an efficient cathode candidate in an MFCs system for sensitive sodium dodecylbenzene sulfonate (SDBS) detection. Boron doping introduces additional defects and improves the dispersibility and oxygen permeability, thereby enhancing the oxygen reduction reaction (ORR) efficiency. The B-rGO-based cathode has demonstrated significantly improved output voltage and power density, marking improvements of 75 % and 58 % over their undoped counterparts, respectively. Furthermore, it also exhibited remarkable linear sensitivity to SDBS concentrations across a broad range (0.2–15 mg/L). Notably, the cathode maintained excellent stability within the test range and showed significant reversibility for SDBS concentrations between 0.2 and 3 mg/L. The highly sensitive and stable B-rGO-based cathode is inspiring for developing more practical and cost-effective toxicant sensing devices.

Optimizing weighted voltage mode control for enhanced output cross-regulation in multi-output DC/DC converters

Weighted voltage mode control is a widely used method for regulating multiple output DC-DC converters, but inconsistent outcomes are often observed in design due to the complexity of the weighting variable optimization. This study proposes an optimization-based approach to accurately estimate the optimal weighting factors for improved output voltage regulation in multiple output forward DC-DC converters. Three optimization algorithms, the Imperialist Competitive Algorithm (ICA), Particle Swarm Optimization (PSO), and Ant Colony Optimization (ACO) are compared for their speed and accuracy in estimating the weighting factors. Additionally, a Fuzzy Logic Controller (FLC) is used to further reduce the overall steady-state error and improve transient characteristics. Simulations are performed using the MATLAB/Simulink software, and the results show that the proposed strategy significantly enhances output cross-regulation in multiple output forward DC-DC converters. The ICA-based weighting factor estimator is found to be the most effective algorithm among the three optimization algorithms tested. The main contribution of this study is to provide a more efficient and accurate method for estimating the weighting factors in multiple output forward DC-DC converters, which can lead to improved performance and reliability in various applications.

A piecewise temperature-curvature compensation bandgap with internal chopper stabilized amplifiers

This paper presented a high-accuracy bandgap reference circuit with novel temperature curvature compensation technology and chopper stabilized technology. The proposed bandgap circuit achieves a good temperature coefficient (TC) without the trimming circuit by high-order adaptive curvature compensation. Besides, we applied the chopper stabilized technology to internal amplifiers in bandgap reference, which reduces the offset voltage of the amplifier and improves output voltage precision and TC. The bandgap circuit has been manufactured in a 180 nm BCD process. The core occupies an active chip area of 160 μm × 370μm. The simulated temperature coefficient is 0.755 ppm/◦C with a wide temperature range of −40 °C∼125 °C. The measurement results indicated that the designed bandgap reference has high precision. The measurement temperature coefficient is 10.07 ppm/◦C. The line regulation of bandgap reference is 0.07 %. Besides, the PSRR of the circuit is −65dB@100 Hz. The current consumption of the circuit is 12.6uA.

High-performance polyaniline-coated electrospun P(VDF-TrFE)/BaTiO3 nanofiber-based flexible piezoelectric nanogenerator

The rapid progress and assimilation of the Internet of Things in modern lifestyles has sparked increased interest in self-powered electronics and wearable sensors. In this study, we present a simple, facile, and cost-effective approach to fabricate polyaniline (PANI)-coated poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE))/barium titanate (BT) nanocomposite nanofiber mats. The addition of PANI-coated BT NPs into the nanofibers greatly enhances the piezoelectric coefficient (d33 ≈ 62 pC N−1), leading to an improved output voltage. Meanwhile, the conductive PANI also improves the electrically conductive network, resulting in enhanced current output. The proposed flexible piezoelectric nanogenerator yielded an excellent figure of merit (14.4×10−11Pa−1), significantly enhancing energy-harvesting performance (an open-circuit output voltage of ∼68 V, a short-circuit current of ∼3 μA, and a remarkable power density of 225 mW m−2). Furthermore, the fabricated flexible devices exhibited an average mechano-sensitivity of 1.2 V kPa−1, showcasing its potential for widespread application in self-powered wearable sensors capable of capturing various human motions in applications such as gesture monitoring and finger motion detection.

A nonlinear electromagnetic vibration energy harvester lubricated by magnetic fluid for low-frequency vibration

Using vibration energy harvesters (VEHs) to achieve self-power is an effective method to ensure long-term use of sensor networks. This paper proposes a nonlinear electromagnetic VEH lubricated by magnetic fluid (MF) for low-frequency vibration energy harvesting. The VEH uses fixed small magnets to reduce natural frequency and prevent moving a magnet stack from flipping, MF for lubrication to improve output voltage under weak vibration, and elastomers to prevent magnet damage under strong vibration. In addition, MF and elastomers can increase the nonlinearity of restoring force, broadening the response frequency of VEHs. The motion state of the VEH is analyzed, and a crank-slider mechanism is used to test the output performance of VEHs. The influence of shell conductivity, the number of fixed small magnets, and length of VEH on output voltage is studied, and the results show that the VEH with an insulated shell, fewer fixed small magnets, and suitable length generates higher output voltage. The MF mainly plays a damping role in strong vibration but mainly plays a lubricating role in weak vibration. For experiments with 15 mm amplitude at 7.9 Hz, the output power density of the VEH without MF and lubricated by MF are 2.436 and 1.862 mW/cm3, respectively. MF damping reduces the output power density by 23.56%. However, for experiments with 7.5 mm amplitude at 3 Hz, the output power for VEHs without MF and lubricated by MF are 0.065 and 0.254 mW, respectively. The output power is increased by 291% with MF lubrication.

Robust fixed-order [formula omitted] controller synthesis for multi-phase converters with input voltage feed-forward

Generated DC voltages of batteries, fuel cells, or supercapacitors as power sources connected in series with DC-DC converters change according to operating conditions. In such cases, the output voltage stability of the multi-phase DC-DC converters is an issue, particularly being subject to noises in the input voltage and load current disturbances. Input voltage feed-forward (IVFF) compensation approaches can improve the output voltage stability of the DC-DC converters in such scenarios. This paper proposes a robust fixed-order H∞ based IVFF control framework by considering sensor noise, input voltage, and load current disturbances to improve output voltage stability and reference tracking performance. The mismatched disturbance transfer functions depending on parasitic resistances are derived to include in the controller synthesis process. An iterative convex-concave optimization-based robust fixed-order controller design algorithm is proposed to optimize the feedback and feed-forward controllers under the stability and performance constraints. This algorithm allows the designing of the controllers simultaneously. The feed-forward controller, whose structure is independent of the system transfer functions, is optimized without any model inversion or extra design steps. The performance of the proposed controller is compared with an integral linear quadratic regulator controller, a sliding mode PID controller augmented with a nonlinear disturbance observer, and a fixed-order robust controller designed with non-smooth techniques. Real-time implementation of the fixed-order control systems is performed on a 2-leg 200 W interleaved boost converter. The performances are discussed under external disturbance effects to show the validity of the proposed control approach.

Electroporation Pulse Generator for Biomedical Applications With Improved Output Voltage Ripple and Reduced Bus Capacitor

Electroporation is a promising cancer treatment based on applying short electric field pulses. In this context, highly versatile pulse generators are required to generate high-voltage low-ripple pulses in the µs range. In the past, several multi-level converters have been proposed to achieve this aim. Achieving constant output voltage and, consequently, electric field is essential to obtain predictable treatments and minimize the risks of tumor relapse. However, significant bus capacitance is required to achieve the required performance, leading to bulky equipment with serious safety implications due to the stored energy. In this letter, a high-performance pulse generator for electroporation is proposed that takes advantage of a multi-level structure with linear voltage regulation to achieve the desired performance with reduced bus capacitance. The proposed converter has been designed and tested experimentally during both laboratory and operation room treatments.

Improving Output Voltage Swing in Cascode Current Mirrors

Improving Output Voltage Swing in Cascode Current Mirrors

Scalable self-integrated all-in-one fabric-based supercapacitors with simultaneous enhancement of output voltage and capacitance

All-in-one supercapacitors show broader application prospect in the field of flexible electronics due to the electrochemical stability and durability. Nonetheless, how to simultaneously enhance the output voltage and capacitance of integrated devices while maintain excellent flexibility and reasonable dimension is a critical challenge for the further development and application of all-in-one supercapacitor. In this work, the self-integrated all-in-one fabric-based supercapacitors (FSCs) with excellent capacitive behavior, flexibility and scalability are designed and fabricated by simply screen-printing the multi-walled carbon nanotubes (MWCNTs) ink on both sides of fabric-based composite separator. The interlocked-like electrode configuration of self-integrated FSC enables electrolyte ions to be transported in transverse and perpendicular directions, and it greatly improved the areal capacitance and reduced internal resistance. Moreover, the assembled FSC exhibits excellent flexibility and stability even under dynamic bending with relatively high strain rates (20% s−1), and 86.1% capacitance is maintained after 1000 bending cycles. Most importantly, the simultaneous series and parallel integration scheme of self-integrated FSCs is realized by versatile screen-printing technique, demonstrating the great potential to simultaneously improve output voltage, overall capacity and potability in a relatively small dimension. Generally, the unique electrode configuration proposes a cost-effective strategy for mass production of flexible energy storage devices.

A novel SVPWM for 3-phase to 5-phase conversion using matrix converter

<span>A novel matrix converter has been developed for 3-phase to 5-phase conversion using a novel space vector pulse width modulation. The matrix converter organized to generate 5-phase AC output voltage from 3-phase input voltage with help of SVPWM method; bidirectional power switches placed in matrix converter controlled by appropriate switching pulse. Space vector pulse width modulation (SVPWM) provides better utilization of applied input voltage, improved output voltage, reduced total harmonic distortion. The bidirectional switch used by the matrix converter decreases stress on the power switch and the influence of harmonic fluctuation in AC output voltage. When compared to traditional approaches, the suggested system offers improved output voltage and current control. Using MATLAB/Simulink and FPGA-cyclone controller, respectively, modelling and experimental results have been given to validate the proposed methodology.</span>

A Performance Enhancement Method for MEMS Thermopile Pirani Sensors Through In-Situ Integration of Nanoforests

In this letter, we report a performance enhancement approach for MEMS thermopile Pirani sensors through in-situ integration of nanoforests. The nanoforests not only increase the light absorption of the thermopile, resulting in an improved output voltage, but also increase the contact area and heat exchange sites for gas molecules due to their high porosity and large surface area to volume ratio, subsequently improve the gas heat conduction, extend pressure detection range and increase sensitivity of the Pirani sensor. With integration of the nanoforests, the lower detection limit of the sensor is widened by one order of magnitude compared with the pristine sensor, and the maximum increment in sensitivity reached 56.7%. Moreover, such a sensor can be easily fabricated with a CMOS-compatible process, thus is suitable for mass production. This work provides a new route to enhance performance of current MEMS thermopile Pirani sensors.

Preview repetitive learning control for islanded microgrids based on equivalent input disturbance approach

Due to the rapid drop in peak dc-link voltage (PDV) caused by environmental changes, as well as the majority of loads being naturally nonlinear, the output voltage of the microgrid inverters is always distorted. To boost the PDV at a low cost and reduce the total harmonic distortion (THD) of output voltage, a strategy is proposed in this paper to synchronously control ac- and dc-sides voltage. A double closed-loop PI controller is used to indirectly control the PDV of Z-source inverter (ZSI). Sinusoidal reference voltage generated by the primary power layer is merged to construct an augmented dynamic system, and an integrated optimal controller on the ac-side is obtained. Preview repetitive control (PRC) and error compensation can improve output voltage tracking accuracy. The state feedback component effectively suppresses the resonance of the filter, lowering the system’s sensitivity to parameter perturbation. Combined with this, the equivalent input disturbance (EID) is used to eliminate the potential interference in microgrids, which can shorten the recovery time of the system. Both simulations and experiments are provided to demonstrate the better performance of the proposed approach in comparison to other different repetitive controllers.

PV Integrated Multifunctional Off-Board EV Charger With Improved Grid Power Quality

This article presents an adaptive notch filter (ANF) based efficient control algorithm for multifunctional grid connected solar photovoltaic (PV) powered electric vehicle (EV) charger to power the EV batteries and simultaneously improve the grid power quality. Furthermore, a multilevel topology is adopted for the grid-facing converter to improve output voltage quality. The ANF accurately estimates the fundamental EV current and grid voltage for generating pure sinusoidal reference current and synchronizing voltage template, respectively. The ANF-based voltage template estimator precisely estimates in-phase and in-quadrature synchronizing voltage templates compared to a phase-locked loop and second-order generalized integrator during nonideal grid voltage conditions. The charger is designed to operate in grid connected operation (GCO) and standalone operation (SO) to optimize the PV generation. In GCO, the charger provides grid current harmonic compensation and reactive power support to the grid. Furthermore, it offers backup power to the residential load during an emergency. The charger control algorithm also includes a grid synchronization technique based on phase error minimization to achieve a smooth and seamless transition from SO to GCO and vice versa. The effectiveness of the proposed control algorithm is validated in a 12.6-kVA <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -board EV charger laboratory prototype. The obtained results verify the charger performance complies with IEEE 1547 standard.

Elimination of Harmonics in Multilevel Inverter Using Multi-Group Marine Predator Algorithm-Based Enhanced RNN

Multilevel inverters (MLI) are becoming more common in different power applications, such as active filters, elective vehicle drives, and dc power sources. The Multi-Group Marine Predator Algorithm (MGMPA) is introduced in this study for resolving transcendental nonlinear equations utilizing an MLI in a selective harmonic elimination (SHE) approach. Its applicability and superiority over various SHE approaches utilized in recent research may be attributed to its high accuracy, high likelihood of convergence, and improved output voltage quality. For the entire modulation index, the optimum switching angles (SA) from Marine Predator Algorithm (MPA) is utilized to control a three-phase 11-level MLI employing cascaded H-bridge (CHB) architecture to regulate the vital element and eliminate the harmonics. The limitation of SHE is that it is difficult to find solutions for nonlinear equations. As a result, specific optimization approaches must be used. Artificial Intelligence (AI) algorithms can handle such a nonlinear transcendental equation successfully, although their time consumption as well as convergence abilities vary. Here, recurrent neural network (RNN) is considered where the hidden neurons are tuned by MGMPA with the intention of harmonic distortion parameter (HDP) minimization, thus called as enhanced recurrent neural network (ERNN). The method’s resilience and consistency are demonstrated by simulation and analytical findings. The MGMPA method is more effective and appropriate than various algorithms including the MPA, Harris Hawks optimization (HHO), and Whale optimization algorithm (WOA), according to simulation data.

Enhanced voltage response in TiO2 nanoparticle-embedded piezoelectric nanogenerator

Poly (vinylidene fluoride) (PVDF) and its copolymers have piqued a substantial amount of research interest for its use in modern flexible electronics. The piezoelectric β-phase of the polymers can be augmented with the addition of suitable fillers that promote β-phase nucleation. In this work, we report an improved output voltage response of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with the incorporation of 10 wt.% Titanium (IV) oxide nanoparticles into the polymer matrix. The nano-filler was dispersed in the polymer matrix to form nanocomposite films via the solution casting technique. X-ray Diffraction and Scanning Electron Microscopy measurements were performed to verify the structure and morphology of the films. Fourier Transform Infrared Spectroscopy revealed enhancement in the β-phase nucleation from ∼15% to ∼36% with the addition of 10 wt.% titania nanoparticles. Thermogravimetric analysis and Differential Scanning Calorimetry results show improved thermal stability of the nanocomposite film, up to 345 °C, as compared to pristine PVDF-HFP. We also demonstrate a facile method for the fabrication of a piezoelectric nanogenerator with β-PVDF-HFP/TiO2 nanocomposite as an active layer. The outputs from the fabricated nanogenerator reached up to 8.89 V through human finger tapping motions, paving way for its potential use in the field of sensors, actuators, and self-sustaining flexible devices.

Nine-level Cascaded H-Bridge Multilevel Inverter for Photovoltaic Sources Based on Hybrid Active Filter

Nowadays, a multilevel inverter is one of the important devices that provides a practical approach device in power system industries because of its features which are less switching losses, lower electromagnetic interference, reduced harmonic distortion, higher DC link voltages, and improved output voltage and current waveforms. Among all existed multilevel inverter, cascaded H-bridge multilevel inverter is the most attractive because of the technology development with megawatt power level. So, the cascaded H-bridge multilevel inverter has been tested and proven as a suitable DC/AC device for medium and high power applications such as renewable energy systems, electric vehicles, and motor drive applications. In this paper, the project is focusing on the combination of a nine-level cascaded H-bridge multilevel inverter connected to photovoltaic (PV) sources and a hybrid powerfilter. This project aims to study and to analyze the results of the proposed system. Thebehaviour and the performance of the designed system have shown that the system offered330V peak output AC voltage with an efficiency of 93.96% and a 5% reduction of THD.This project will be carried out only in Matlab/Simulink software.