Improved Output Voltage Research Articles

Indirect MPC method with improved output voltage and current waveforms for MMCs

Indirect MPC method with improved output voltage and current waveforms for MMCs

DESIGN AND SIMULATION OF A SOLAR-WIND STAND-ALONE SYSTEM WITH A SEVEN-LEVEL INVERTER

During an energy conversion process, the total harmonic distortion and losses will increase while its power stability decreases. Multilevel inverter technology can be utilized to alleviate the shortcomings of conventional inverters. These technologies have become recognized as cost-effective solutions for a wide range of industrial applica-tions. Reduced component losses and lower switching losses, as well as improved output voltage and current wave-forms are the first advantages of this design. In multilayer inverters, elimination of harmonic components in the inverter output voltage and current is crucial. This paper proposes a system that consists of three different renewable energy sources. Two of them are PV solar systems while the third is wind turbine simulated in MATLAB Simulink. Seven-level inverters based on switch reduction techniques are proposed in this paper. The proposed system design is verified in the absence of PV systems to produce five voltage levels as a contingency in PV systems.

MSVM ‐based hybrid energy‐fed quasi‐Z‐source cascaded H‐bridge inverter for grid‐connected system

Hybrid energy sources are much needed to meet the power demand for various real-time applications, and the desired output level is attained with the help of various advanced power converter topologies. Here, the hybrid energy source-fed quasi-Z-source cascaded H-bridge inverter (QZS-CHI) is implemented for a grid-connected system. The conventional multilevel inverter topologies are suitable for voltage buck operation, but this proposed system includes quasi-Z-source inverter network, which leads voltage buck-boost operation without any additional dc-dc converter. Modified space vector modulation (MSVM) technique is developed to control the QZS-CHI system, which leads to reduced total harmonic distortion(THD), reduced common-mode voltage (CMV), controlled output current, and improved output voltage. The proposed system QZS-CHI is energized using a hybrid energy source with a photovoltaic (PV) system and wind energy conversion system (WECS). With the help of shoot through mode in QZS, the output voltage is boosted without an additional converter and CMV is minimized by the proper utilization of medium and small switching state vectors. To assess the proposed technique, a laboratory prototype model is built and analyzed under different cases. From the obtained results, it is observed that the proposed method reduces THD to 2.15% for output voltage and 2.99% for output current, and common-mode voltage is reduced to Vdc/6 times of applied dc voltage.

Comparative analysis of 3D‐SVM and 4D‐SVM for five ‐phase voltage source inverter

Pulse width modulation (PWM) methods play a major role to control the various power electronic converters to progress the recital of the system. In this paper, a comparative analysis is done for three dimensional space vector modulation (3D-SVM) and four dimensional space vector modulation (4D-SVM) for five-phase voltage source inverter. 3D-SVM method comprises all qualities of conventional SVM; switching time calculation is simple and much suitable for three-phase system; where in five-phase system, it has redundant switching state vectors. 4D-SVM includes advantages of 3D-SVM and other conventional methods, it employs only nonredundant switching state vectors; it directs to diminish the intricacy in switching time calculations and avoids trigonometric calculations and look up tables for reference vector identification. The various parameters such as total harmonic distortion, improved output voltage, minimized common mode voltage and switching time calculation are analyzed and compared for 3D-SVM and 4D-SVM techniques. Simulation and hardware results are acquired and established using matlab simulink and FPGA processor, respectively.

Fabrication of vibration sensors using precursor molar concentration varied ZnO nanostructures grown by refresh hydrothermal method

PurposeVarious approaches have been made to alter the vibration sensing properties of zinc oxide (ZnO) films to achieve high sensitivity. This paper aims to report the experimental study of the fabrication of precursor molar ratio concentration varied ZnO nanostructures grown on rigid substrates using the refresh hydrothermal method. The effect of these fabricated ZnO nanostructures-based vibration sensors was experimentally investigated using a vibration sensing setup.Design/methodology/approachZnO nanostructures have been grown using low temperature assisted refresh hydrothermal method with different precursor molar concentrations 0.025 M (R1), 0.075 M (R2) and 0.125 M (R3). Poly 3,4-ethylenedioxythiophene polystyrene sulfonate, a p-type material is spun coated on the grown ZnO nanostructures. Structural analysis reveals the increased intensity of the (002) plane and better c-axis orientation of the R2 and R3 sample comparatively. Morphological examination shows the changes in the grown nanostructures upon increasing the precursor molar concentration. The optical band gap value decreases from 3.11 eV to 3.08 eV as the precursor molar concentration is increased. Photoconductivity study confirms the formation of a p-n junction with less turn-on voltage for all the fabricated devices. A less internal resistance of 0.37 kΩ was obtained from Nyquist analysis for R2 compared with the other two fabricated samples. Vibration testing experimentation showed an improved output voltage of the R2 sample (2.61 V at 9 Hz resonant frequency and 2.90 V for 1 g acceleration) comparatively. This also gave an increased sensitivity of 4.68 V/g confirming its better performance when compared to the other fabricated two samples.FindingsPhotoconductivity study confirms the formation of a p-n junction with less turn-on voltage for all the fabricated devices. A less internal resistance of 0.37 kΩ was calculated from the Nyquist plot. Vibration testing experimentation proves an increased sensitivity of 4.68 V/g confirming its better performance when compared to the other fabricated two samples.Originality/valueVibration testing experimentation proves an increased sensitivity of 4.68 V/g for R2 confirming its better performance when compared to the other fabricated two samples.

Boosting Performance of Self-Polarized Fully Printed Piezoelectric Nanogenerators via Modulated Strength of Hydrogen Bonding Interactions.

Self-polarized piezoelectric devices have attracted significant interest owing to their fabrication processes with low energy consumption. Herein, novel poling-free piezoelectric nanogenerators (PENGs) based on self-polarized polyvinylidene difluoride (PVDF) induced by the incorporation of different surface-modified barium titanate nanoparticles (BTO NPs) were prepared via a fully printing process. To reveal the effect of intermolecular interactions between PVDF and NP surface groups, BTO NPs were modified with hydrophilic polydopamine (PDA) and hydrophobic 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) to yield PDA-BTO and PFD-BTO, respectively. This study demonstrates that the stronger hydrogen bonding interactions existed in PFD-BTO/PVDF composite film comparative to the PDA-BTO/PVDF composite film induced the higher β-phase formation (90%), which was evidenced by the XRD, FTIR and DSC results, as well as led to a better dispersion of NPs and improved mechanical properties of composite films. Consequently, PFD-BTO/PVDF-based PENGs without electric poling exhibited a significantly improved output voltage of 5.9 V and power density of 102 μW cm−3, which was 1.8 and 2.9 times higher than that of PDA-BTO/PVDF-based PENGs, respectively. This study provides a promising approach for advancing the search for high-performance, self-polarized PENGs in next-generation electric and electronic industries.

Experimental verification of mixed metal oxide-based sensor for multiple sensing application

Mixed Metal Oxide (MMO) based piezoelectric sensor was fabricated using Zinc Oxide (ZnO) and Ferric Oxide (Fe2O3). The X-Ray diffraction pattern shows the presence of ZnO and Fe2O3 with the respective characteristic peaks. Field Emission Scanning Electron Microscope confirms the ZnO nanorods grown using the hydrothermal method and shows the deposition of Fe2O3 nanoparticles on the ZnO nanorods. The electrical analysis using photoconductivity study reveals the formation of p-n junction in both the samples. The fabricated MMO sensor when subjected to piezoelectric sensing set up gave an improved output voltage of 1.32 V for 1 g input acceleration compared to the other. Similarly, when both the sensors were exposed to gas sensing setup, improved sensitivity of 7.66 and 0.791 for 100 ppm of Carbon Monoxide and Methane at room temperature respectively was obtained when compared to the other sensor fabricated.

A Concurrent Triple-band RF Energy Harvesting Circuit for IoT Sensor Networks

In this paper, a concurrent triple-band RF energy harvesting circuit is proposed. The proposed circuit incorporates a triple-band microstrip antenna combining a low-loss diplexer and three compact RF rectifiers. The proposed circuit operates concurrently at three popular frequency bands: GSM-900, GSM-1800, and 2.45 GHz. To improve output voltage and efficiency, three rectifiers are connected in a stacked topology. The simulated and measured results demonstrate that the circuit operates well in concurrent bands. Moreover, the proposed circuit exhibits a low-complexity structure and compactness in size. These advantages make the circuit a strong potential candidate for running low-power devices in IoT sensor networks.

Reactive Power Control and Neutral Current Elimination of Four Wire Five Level NPC Inverter based STATCOM using 3D-SVPWM Technique

In this paper, three phase four wire five level Neutral Point Clamped Inverter (NPCI) based Static synchronous Compensator (STATCOM) is implemented for reactive power control and neutral current elimination. Three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) control strategy is developed to control this 5-level NPC inverter. The behaviour of static synchronous compensator is analyzed and reactive power control is done using constant DC voltage. The objective of this compensating method is to provide balanced and sinusoidal source currents under unbalanced and nonlinear load conditions and reactive power control. The 3D-SVPWM technique provides reduced harmonic content in output voltage and current, controlled source current, minimized common mode voltage and improved output voltage. In 3D-SVPWM, switching pulses are generated with non-redundant switching states, which lead to reduce the complexity in switching time calculation and computational time is less. The highlights of the paper includes the neutral current is reduced to 0.25A, source current harmonics is minimized and it provides balanced and sinusoidal source currents with help of STATCOM compensation. The simulation and experimental results demonstrates the sinusoidal and harmonics free source current and minimized neutral current for four wire five level NPCI based STATCOM.

A hybrid piezoelectric composite flexible film based on PVDF-HFP for boosting power generation

Nowadays, the development of sustainable and wearable energy harvesters is gaining an increasing interest. Herein, an approach used to develop a high performance flexible nanogenerator based on hybrid piezoelectric composite is reported. The approach consists first of employing solution mixing method with different solvents to determine the suitable solvent for achieving higher piezoelectric property of the piezoceramic polymer composites. Then, integration of conductive silver nanoparticles is done to boost the performance of the nanogenerator (NG). Different aspects are considered which are the homogeneity of particles distribution within PVDF-HFP and the crystallinity of the composite using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). This study demonstrates the efficiency of dimethyl formamide (DMF) solvent to increase the rate of crystalline phases due to their moderate evaporation rate and their high dipole moment that leads to enhanced piezoelectric performance. This approach proves its effectiveness to strengthen the piezoelectric performance especially by doping with silver nanoparticles (Ag NPs). The composite exhibits improved output voltage around 2.21 V and an output power of 0.22 μW, which are, respectively, around three times and 9 times higher than the composite without Ag NPs. In addition, the NG shows good stability over 900 cycles illustrating their robustness. The followed approach extends the performance limits of PVDF-HFP based NGs and their potential applications. Also, we have proved the potential of the optimized NG to harvest mechanical energy from human activities, with ability to generate around 3.56 V by striking with a palm hand.

Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application

This paper investigates a constant on-time controller (COT) with internal ramp compensation and improved output voltage accuracy for point of load applications. The pulse width modulation (PWM) output is generated based on internal ramp: by sensing the regulated output voltage and comparing it to an internal reference target, an error signal is generated. This error signal is used to generate a reference for an added ramp signal, which is compared against an error voltage to generate a PWM trigger signal. An adaptive constant on-time scheme ensures a fairly constant switching frequency over a wide range of input and output voltages. This COT control algorithm is able to achieve high accuracy regulation (±0.5% of target) and fast transient response during load step change. A frequency domain small signal model is proposed, and an open loop gain transfer function is developed for this COT control system. The proposed small signal model and design analyses are verified with SIMPLIS simulations and experimental results.

Boosting piezoelectric response of PVDF-TrFE via MXene for self-powered linear pressure sensor

Piezoelectric film pressure sensors are forthcoming choices for self-powered flexible and portable electronics because of their unique advantages in instant response and linear pressure-electrical signal relationship. However, it is commonly of challenge to achieve high output voltage response to pressure in piezoelectric polymer films. Here, we report a piezoelectric film pressure sensor fabricated by electrospun polyvinylidene-fluoride-trifluoroethylene (PVDF-TrFE)/MXene nanofiber mats. As a new two-dimensional nanomaterial, MXene has not only a large amount of surface functional groups to enable interaction with the dipoles of PVDF-TrFE molecular chains, but also high electrical conductivity to potentially increase the polarization of PVDF-TrFE during electrospinning. As such, by comparison with the control pressure sensor consisting of neat PVDF-TrFE film, the composite film sensor shows significantly improved output voltage, and the improvements are closely dependent on MXene content. For instance, the composite film with 2.0 wt% MXene can achieve an instantaneous output power density of ~3.64 mW/m2 under the pressure of 20 N with the frequency of 1 Hz. Such piezoelectric PVDF-TrFE/MXene films are capable of sensing body motion for healthcare. Furthermore, the hydrophilicity of MXene allows the film pressure sensor to monitor humidity change, thus the composite film sensor demonstrates potential application in multifunctional electronic skins.

Single‐phase hybrid multilevel inverter topology with low switching frequency modulation techniques for lower order harmonic elimination

A new single-phase asymmetrical multilevel inverter (MLI) is presented in this study. The proposed topology generates a staircase output voltage waveform with a maximum number of levels using less number of components compared to several existing and recent topologies. The basic module consists of a combination of two isolated DC sources with ten switches that produce all the possible number of levels. Other advantages of the proposed MLI include improved output voltage performance and a low blocking voltage of the switches. The low switching frequency pulse width modulation (LSF-PWM) technique has been used for the generation of gate pulses. In the LSF technique, selective harmonic elimination (SHE) and fundamental switching frequency PWM techniques have been discussed for the better output voltage waveform. The optimised switching angles with SHEPWM has been calculated using particle swarm optimisation considering the different combination of the elimination of lower order harmonics. Simulation work was carried out using MATLAB/SIMULINK, and a prototype was implemented to validate the proposed MLI module. Simulation and experimental results have been provided in the study to show the performance of the proposed topology with these modulation techniques.

Design of high precision and high power bidirectional adjustable power supply

Abstract ITER (International Thermonuclear Experimental Reactor) sensor steady-state test platform needs high power supply with high steady-state precision output voltage. In the field of high voltage power supply applications, there is often a contradiction between the power supply capability and the switching frequency of high power switching devices. Limited by switching loss, the switching frequency of high power switching devices is low, which will generate a lot of harmonic in the output voltage. In order to meet the requirement of power supply for high-precision output voltage, the design of high power supply adopts the method of combining H-bridge cascaded topology with carrier phase shift PWM control scheme, which can effectively improve output voltage waveform in the design of high power supply. The harmonic analysis and simulation are carried out, and the experimental results verify the validity of the experimental scheme.

Improved Output Voltage of a Nanogenerator with 3D Fabric.

Electrically enhanced triboelectric nanogenerators (TENGs) using 3D fabrics and polydimethylsiloxane (PDMS) are suggested for next-generation wearable electronics. TENGs with fabric-fabric- fabric (FFF) and PDMS-fabric-PDMS (PFP) structures were fabricated with ordinary 2D fabrics and honeycomb-like 3D fabrics. A 3D fabric TENG with an FFF structure showed an output voltage of 7 V, 7 times higher than a 2D fabric FFF structured TENG. Interestingly, an extremely high output voltage of 240 V was achieved by a 3D fabric PFP structured TENG. This was attributed to the high surface frictional triboelectric effect between fabric and PDMS and also marginal 3D structure in the 3D fabric active layer.

Development of In-Situ Poled Nanofiber Based Flexible Piezoelectric Nanogenerators for Self-Powered Motion Monitoring

Energy harvesting technologies have found significant importance over the past decades due to the increasing demand of energy and self-powered design of electronic and implantable devices. Herein, we demonstrate the design and application of in situ poled highly flexible piezoelectric poly vinylidene fluoride (PVDF) graphene oxide (GO) hybrid nanofibers in aligned mode for multifaceted applications from locomotion sensors to self-powered motion monitoring. Here we exploited the simplest and most versatile method, called electrospinning, to fabricate the in situ poled nanofibers by transforming non-polar α-phase of PVDF to polar β- phase structures for enhanced piezoelectricity under high bias voltage. The flexible piezoelectric device fabricated using the aligned mode generates an improved output voltage of 2.1 V at a uniform force of 12 N. The effective piezoelectric transduction exhibited by the proposed system was tested for its multiple efficacies as a locomotion detector, bio-e-skin, smart chairs and so on.

High Gain Quasi-Switched Boost Inverter With Optimal Performance Parameters

Numerous Z-source three-phase inverters are developed for realizing higher voltage gain which are suitable to use in hybrid electric vehicle to drive the electric machine. However, higher voltage and current stress of the passive elements and semiconductor devices are the major limitations of the reported Z-source inverters. In this article, a new quasi-switched boost three-phase inverter is proposed which has the following features: 1) very low continuous input current; 2) reduced voltage stress; 3) reduced current stress; 4) shoot through immunity; 5) single stage voltage conversion from dc to ac; and 6) improved output voltage quality by utilizing higher modulation index. The operation, steady-state analysis, and design guidelines for the proposed converter are discussed in detail. To prove the feasibility of the proposed inverter, a comparative analysis is also presented with the state-of-the-art converters. An experimental setup is designed on printed circuit board and tested for 400 W power rating.

Cascaded Multilevel PV Inverter With Improved Harmonic Performance During Power Imbalance Between Power Cells

The difference in power cell irradiances in cascaded multilevel converters results in different duty cycles among those cells when maintaining the maximum power point tracking (MPPT). However, the difference in cell duty cycles is undesired since it is proportional to the output voltage and current distortions. To this regard, a multilevel topology for photovoltaic (PV) applications is proposed, where an H6 bridge power cell is used instead of an H-bridge one. In case of solar irradiance mismatch among the power cells, the proposed converter injects power with lower voltage from the shaded cells without altering the PV voltage; hence maintaining the MPPT operation. This modification allows us to retain an equal duty cycle in all the power cells whatever the meteorological conditions are present; consequently, maintaining good output voltage and current waveform qualities. To test the effectiveness of the proposed solution, a detailed simulation model as well as an experimental prototype is built. The obtained results show that the proposed topology provides significantly improved output voltage and current qualities compared to the cascaded H-bridge one. The performance of the proposed topology compared to one offering improved harmonics performance, according to the European efficiency, has been also compared, where an enhancement of 2.64% has been registered.

Sensor Malfunction Detection and Mitigation Strategy for a Multilevel Photovoltaic Converter

Cascaded H-bridge (CHB) based converters have several advantages including modularity, isolated DC-side voltage, and improved output voltage quality. These multilevel converters are increasingly used in photovoltaic (PV) systems. With the number of H-bridge submodules (SM) and sensors increased due to the cascaded topology, the converter becomes more prone to sensor malfunctions. This article proposes a method to make a CHB-based PV converter resilient to sensor malfunctions using a real-time state estimation–based malfunction detection algorithm. The proposed method is validated using simulation studies in MATLAB/SIMULINK and experimental studies on a test system. It is shown that a nine-level CHB-based PV system can operate normally even when one sensor measurement is missing.

Model predictive voltage control of a single-phase inverter with output LC filter for stand-alone renewable energy systems

This work offers a simple and efficient model predictive voltage control strategy with a two-step prediction for improved output voltage control of single-phase inverter used for stand-alone renewable energy systems. The single-phase inverter with output LC filter is used to provide a sinusoidal output voltage, regardless of the arbitrary consumer load profiles. The suggested control algorithm uses the discrete-time model of the inverter and LC filter for two-step prediction of the output voltage for each possible switching state. Then, the control algorithm selects the switching state which minimizes the error between the output voltage and its reference without using any inner controllers or modulators. An accurate extrapolation methodology with reduced computational burden is used to predict the dynamic changes in the output voltage reference. The switching frequency reduction is also attained by considering a simple constraint in the suggested algorithm. Simulation results are presented to verify the feasibility and excellent performance of the suggested controller under linear and nonlinear load conditions, compared to a conventional voltage control strategy based on PI regulators and PWM. Furthermore, experimental tests using a dSPACE system with DS1104 controller have been done to confirm the simulations results.