Magnitude Of Output Voltage Research Articles

Energy harvesting and human motion sensing of a 2D piezoelectric hybrid organic–inorganic perovskite

Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have garnered plentiful attention as a result of their exceptional structural flexibility and multiple applications. In this study, we present a 2D HOIP (CHA)2PbBr4 (CHA = cyclohexylamine), for its potential applications in piezoelectricity, such as strain energy sensing and harvesting. Flexible composite films of (CHA)2PbBr4/PDMS (PDMS = polydimethylsiloxane) with a sequence of weight ratios (0, 5, 10, 15, 20 wt %) of (CHA)2PbBr4 were fabricated to analyze the energy harvesting properties. Experimental results demonstrated that a device with 15% composition exhibited the most optimized performance in energy harvesting, producing a peak magnitude of output voltage of 11.6 V, a short-circuit current of 0.38 µA, and a power density of 6.77 µW/cm2, along with notable stability exceeding 4000 cycles. Furthermore, this device exhibited high sensitivity in monitoring many varieties of human movements, such as finger bending and tapping, elbow bending, and gentle foot stamping. The findings of this study indicate that this 2D HOIP holds significant potential for use in flexible sensing and intelligent wearable devices.

A Three-Level Neutral-Point-Clamped Converter Based Standalone Wind Energy Conversion System Controlled with a New Simplified Line-to-Line Space Vector Modulation

Wind power systems, which are currently being constructed for the electricity worldwide market, are mostly based on Doubly Fed Induction Generators (DFIGs). To control such systems, multilevel converters are increasingly preferred due to the well-known benefits they provide. This paper deals with the control of a standalone DFIG-based Wind Energy Conversion System (WECS) by using a three-level Neutral-Point-Clamped (NPC) converter. The frequency and magnitude of the stator output voltage of the DFIG are controlled and fixed at nominal values despite the variable rotor speed, ensuring a continuous AC supply for three-phase loads. This task is achieved by controlling the DFIG rotor currents via a PI controller combined with a new Simplified Direct Space Vector Modulation strategy (SDSVM), which is applied to the three-level NPC converter. This strategy is based on the use of a line-to-line three-level converter space vector diagram without using Park transformation and then simplifying it to that of a two-level converter. The performance of the proposed SDSVM technique in terms of controlling the three-level NPC-converter-based standalone WECS is demonstrated through simulation results. The whole WECS control and the SDSVM strategy are implemented on a dSPACE DS 1104 board that drives a DFIG-based wind system test bench. The obtained experimental results confirm the validity and performance in terms of control.

Performance Characteristics of a Newly Developed Asymmetric Seven-Level Inverter Utilizing Various Hybrid Pulse Width Modulation Strategies

This study unveils a notable breakthrough in inverter technology, holding promise for substantial improvements in voltage quality and the attenuation of harmonic distortions within power systems. This study concentrates on the design and implementation of a novel Seven-Level Asymmetric Inverter (NSLAI) by incorporating various hybrid Pulse Width Modulation (PWM) techniques. The primary goal is to improve the output voltage magnitude while decreasing the Total harmonics compared to conventional PWM methods. The investigation introduces a novel Seven-Level Asymmetric Inverter (NSLAI) with innovative Hybrid Pulse Width Modulation (PWM) strategy. The purpose of this study is to investigate the distinct features of a recently developed asymmetric seven-level inverter, with a focus on exploring its characteristics through the implementation of diverse hybrid pulse width modulation strategies. Hybrid PWM methodology intricately centers on enhancing voltage quality and achieving better harmonious spectral characteristics. The gate signal producing approach for this suggested PWM technology incorporates a hybrid PWM methodology that combines trapezoidal and sinusoidal waveforms, as well as a standard triangular carrier signal enabling NSLAI. The hybrid version of PWM practices is deliberately used to generate switching signals for the NSLAI. An intensive evaluation of numerous indicators of effectiveness across multiple modulation indexes leads in the demonstrating of quantitative findings that compare the unique Hybrid PWM practice with established PWM tactics. Notably, the hybrid reference Carrier Overlapping strategy has emerged as a leading approach surpassing conventional pulse width modulation techniques. It achieves a significantly higher fundamental Root Mean Square voltage output and remarkably lower percentage of Total Harmonic Distortion values compared to all within the hybrid reference Variable Frequency strategy. The principal analytical tool used in the modeling investigation is MATLAB-SIMULINK. This study marks a watershed moment in the development of inverters, claiming significant improvements in battery power quality and distortion caused by harmonics avoidance across power systems, as evidenced by extensive simulation and prototype-based discoveries.

A New Double-Switch SEPIC-Buck Topology for Renewable Energy Applications

In addition to their conventional use in electric motor drives, DC-DC converters have a variety of other uses, such as energy storage, energy conversion, cyber security systems, uninterruptible power supplies, and renewable energy systems. An innovative DC-DC converter is suggested in this article. Designing a new, high-gain DC-DC converter scheme known as a double-switch SEPIC-buck converter (DSSB) is possible after making some adjustments to the SEPIC converter that is currently known in accordance with accepted techniques. The output voltage magnitude of the proposed converter is either larger than or less than the input voltage magnitude and is the same sign as the input voltage. According to the theoretical and analytical study that has been supported by the real-world application, high voltage gain, low switching stress, and low inductor current ripple are the main characteristics of the proposed DSSB converter. The related small-signal model was also used to build the closed-loop system. The frequency response and output voltage behavior were investigated when the input source voltage abruptly changed as a step function. Based on the comparison study with other DC-DC converters, the DSSB converter outperforms currently known DC-DC converters such as Buck, SEPIC, Boost, Buck-Boost, and other SEPIC converter topologies in terms of voltage gain, harmonic content, normalized current ripple, dynamic performance, and efficiency. Additionally, the frequency response and control of the proposed converter using an alternate current (AC), small-signal, analysis-based, current-mode control technique are both provided. Thus, the DSSB is regarded as safe in overcurrent situations because of the small-signal analysis with the current control strategy. As a result of the verification of the proposed control technique, the resistance to changes in the DSSB parameters, improved dynamic performance, and higher control accuracy are further advantages of current-mode control based on small-signal analysis over other control approaches (PI controllers). Finally, the experimental and simulation results from Simplorer 7 and MATLAB/Simulink are used to validate the findings of the analytical and comparative investigation.

Development of a lead-free, high-frequency ultrasound transducer with broad bandwidth and enhanced pulse-echo response, employing β-Ni(OH)2/PVDF-TrFE piezoelectric composite

Piezoelectric composite-based high-frequency ultrasound transducers (USTs) have gained significant prominence as a leading and effective tool in non-invasive medical diagnosis, non-destructive testing and diverse industrial applications. In this study, we present the fabrication of a lead-free, high-frequency ultrasound transducer (P-UST), having a very simple and unique assembly procedure. To achieve this, we employed PVDF-TrFE based piezoelectric composite thin film (NTr5) integrated with a transition metal hydroxide (β-Ni(OH)2 nanoplates) and demonstrated its outstanding performance, thereby showcasing its potential in various applications. The composite exhibited exceptional β-phase crystallization, reaching impressive maximum value of 90.04%, owing to the favorable interaction between electrostatic ions and dipoles, along with the presence of strong surface polarization. Upon analysis, remarkable piezoelectric (d33∼50.22 pm/V) and ferroelectric properties were observed in the composite material, accompanied by significant enhancement in surface roughness. Here, the piezoelectric property's impact on UST output is well-explained using Maxwell's equation. P-UST, being a versatile system, is capable of generating and receiving pulse signals. By conducting a pulse-echo test on an aluminium block with ultrasound gel, we achieved a peak-to-peak output voltage of 5.19 V, surpassing the output voltage magnitude of any previously reported UST in this field. The Fast Fourier transformed data of the voltage output revealed an impressive −6 dB bandwidth of 51.22 MHz (102.4%) with a high central frequency of 50.01 MHz. Hence, our P-UST's exceptionally high central frequency promises significantly enhanced ultrasound image resolution, which expands the potential for highly accurate medical assessments for advanced healthcare outcomes and improving patient well-being.

Smooth Pulse Number Transition Strategy Considering Time Delay in Synchronized SVPWM

In high power motor drive systems, synchronized space vector pulsewidth modulation (synchronized SVPWM) is widely used to guarantee stable control performance. Synchronized SVPWM has a characteristic that the switching frequency varies abruptly when the pulse number transitions. This article proposes a pulse number transition point at which the phase difference is minimized to remove the phase difference of the sampling point that appears during synchronized SVPWM control. In addition, for a smooth pulse number transition of synchronized SVPWM, a compensation method for the magnitude and phase error of the inverter output voltage due to the time delay and a method of removing the existing phase difference without using a phase-locked loop are proposed in consideration of the characteristic of changing switching frequency. The validity and the implementation of the proposed method are verified by experimental results using a high-power inverter driving 332 kW interior permanent magnet synchronous motor (IPMSM).

Model-Based Field Winding Interturn Fault Detection Method for Brushless Synchronous Machines

The lack of available measurements makes the detection of electrical faults in the rotating elements of brushless synchronous machines particularly challenging. This paper presents a novel and fast detection method regarding interturn faults at the field winding of the main machine, which is characterized because it is non-intrusive and because its industrial application is straightforward as it does not require any additional equipment. The method is built upon the comparison between the theoretical and the measured exciter field currents. The theoretical exciter field current is computed from the main machine output voltage and current magnitudes for any monitored operating point by means of a theoretical healthy brushless machine model that links the main machine with the exciter. The applicability of the method has been verified for interturn faults at different fault severity levels, both through computer simulations and experimental tests, delivering promising results.

Novel Voltage-Balance Control of Four-Level Hybrid-Clamped Converter With Open-Loop Optimized Common-Mode Voltage Injection

The four-level hybrid-clamped converter (HCC) is a new high-efficiency dc–ac converter. However, its dc-link capacitors face challenging voltage fluctuation issues at low frequencies, resulting in the distorted ac current and oversize converter volume. This letter presents a simple and effective control method of the HCC using open-loop common-mode voltage (CMV) injection. The mathematical model of the CMV and the capacitor voltage fluctuations is derived. The optimal CMV algorithm with the maximum suppression effect of capacitor voltage fluctuations is proposed as well as the implementation method. The microlevel mechanism of the proposed method in suppressing voltage fluctuation is clarified. The capability of the proposed method in improving dc voltage utilization is explored. Compared with existing methods, the proposed one reduces dc-link voltage sensors and computation complexity and mitigates CMVs at the load side. The optimal CMV is approximately 25% of the output voltage magnitude, and enhances the dc-bus voltage utilization by 12%. Results demonstrate that voltage fluctuations of HCC capacitors are reduced by over 60%. The proposed method has a solid dynamic balancing capability and works well for the wide-range frequency and modulation index.

3D‐Printed Stacked Ionic Assemblies for Iontronic Touch Sensors

AbstractSensing is the process of detecting and monitoring any physico‐chemical environmental parameters. Herein, new self‐powered iontronic sensors, which utilize touch‐induced ionic charge separation in ionically conductive hydrogels, are introduced for potential use in object mapping, recognition, and localization. This is accomplished using high‐resolution stereolithography (SLA) 3D printing of stacked ionic assemblies consisting of discrete compartments having different ion transport properties. The latter assemblies readily allow programming the output voltage magnitude and polarity by means of variations in ion type, charge density, and cross‐linking density within the iontronic device. Voltages of up to 70 mV are generated on application of compressive strains of as much as 50% (≈22.5 kPa), with the magnitude directly proportional to stress, and the polarity dependent on the sign of the mobile ion. As a proof‐of‐concept demonstration, the resulting touch sensors are integrated on the fingertip to enable the tactile feedback, mimicking the tactile perception of objects for recognition applications. In addition, it is proposed that streaming potential is the underlying mechanism behind the iontronic touch sensors. The electromechanical response is therein consistent with a streaming potential model.

Overmodulation Strategy for Torque Balance of Dual-Motor Systems Considering Angle Offset

An overmodulation method is proposed for an in-wheel system where two motors are coupled to a sum gear. In the dual-motor dual-inverter single shaft systems, the output voltage magnitudes of two inverters are not the same in the overmodulation range due to the angle offset between two motors. In this article, to maintain torque balance in the overmodulation region, holding vectors are defined between adjacent vertices of two voltage hexagons. Around these vectors, the holding region is also defined by the holding angle. If a reference voltage vector is in the holding region, it is modulated to the holding vector; otherwise, it is modulated to the vector on the arc of inscribed circle. For a given the modulation index (MI), the holding angle is obtained based on the Fourier series expansion. The proposed method keeps the output voltages of two inverters the same even if two motors have the angle offset. Further, it has the characteristic of maintaining the linearity between the reference and output MI to the maximum MI. The proposed overmodulation method is demonstrated by simulation and experimental results.

A 5 V-to-32 V Input PVT-Robust Charge-Pump Circuit with Adjustable Output in a 0.18 μm BCD Process

In this paper, a new closed-loop charge-pump circuit with adjustable output voltage and an on-chip compensation technique is proposed. The environmental temperature and process corner can be detected with an on-chip detection circuit and automatically feedback an adjusted reference voltage. With this, the magnitude of the charge-pump output voltage with Pulse-Width Modulation (PWM) can be compensated. The charge-pump circuit is designed and verified with a 180 nm Bipolar-CMOS-DMOS (BCD) process, and its output voltage at different process, voltage, and temperature (PVT) is controllable with low ripple. There are three selections for adjusting the output voltage: +5 V/+7 V/+10 V shifts, with the supply voltage ranging from 5 V to 32 V. It can remain tunable and stable at any shifts. The maximum deviation is ±0.265%, and the maximum load current can reach 30 mA. The ripple voltage is less than 0.3% (Δ Vripple/Vout) underthe maximum load. The Monte Carlo simulation results show that the worst case of the process sensitivity (σ/μ) is 0.1%. The charge-pump core area is 0.308 mm2, and the power consumption is 4.753 mW. The circuit can produce high-precision output and is suitable for high-side driving IC applications.

Electrical Connection Configurations for Polyvinylidene Fluoride Nanofabrics With Enhanced Piezoelectric Response

Various electrical connection configurations for piezoelectric nanofabrics (PNFs) fabricated from electrospun polyvinylidene fluoride (PVDF) nanofibers and yarns were realized through different electrode designs, including interdigitated wire electrodes, screen electrodes, core-sheath electrodes, and their combinations. The effects of the electrode designs and weaving modes were investigated on the electromechanical performance. It was found that the piezoelectric output of the PNFs in response to mechanical input was significantly improved by increasing the contact area between the electrodes and the active piezoelectric nanofibers, and thus enhancing the connectivity of all the conductive elements in the PNFs. Large output voltage magnitude (~1.4 V) was observed in the PNF samples made of piezoelectric core-sheath yarn with optimized electrode connection and coverage. Our results here clearly prove the high importance of electrical connection configuration to the performance of PNFs. We believe there is a great room to optimize electrode designs and electrical connections for improved piezoelectric fabric sensors and transducers.

An Optimal Zero-Sequence Voltage Injection Strategy for DVR Under Asymmetric Sag

This article introduces an optimal zero-sequence voltage injection strategy (OZVIS) for the three-phase dynamic voltage restorer (DVR), which can effectively reduce the output voltage magnitude of DVR in case of asymmetric sags in a three-phase, three-wire power system, so as to improve the compensation capacity of the device. The conventional compensation strategy improves the active power or reduces the voltage amplitude of the DVR through phase rotation, but the two functions are difficult to achieve together. In this article, the operation principle of OZVIS is first introduced. Then, the optimality and effectiveness of the strategy are theoretically demonstrated by means of a plane geometric modeling approach. In addition, the reduction extent using OZVIS in different voltage sag types is quantified, which is based on the minimum energy compensation strategy. Furthermore, a digital “plug-in” algorithm implementation for the proposed strategy is elaborated. Finally, the experimental results will be shown to verify the feasibility and effectiveness of OZVIS under an asymmetric situation. Moreover, the adaptability under a symmetric situation will also be illustrated.

A-Si TFT Integrated Gate Driver Workable at −40°C Using Bootstrapped Carry Signal

A thin-film transistors (TFTs) integrated gate driver which can work well at low temperature down to -40 °C is proposed and demonstrated. The carry signal (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> ) of the driver, being generated through the voltage bootstrapping approach using a C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> -connected capacitor, is used to pre-charge the following stage of the driver. As the rising and falling time of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> is much shorter than that of the gate driving signal G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> , the bootstrapping voltage is increased and voltage loss of the pre-charge transistor can be much reduced, to avoid the driver’s malfunction at low temperature. This structure further benefits maintaining the driving speed over long operation time at high temperature. On the other hand, the G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> , instead of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> , is used to reset the gate driver to suppress the voltage feed-through effects. One single stage of the driver consists of 11 TFTs and 2 capacitors, driven by 4 clock signals with the duty ratio of 25%. An a-Si:H TFTs implemented single stage circuit of the driver occupies an area of 250 μm×1099 μm. Measurements show that the output voltage magnitude can be maintained well when temperature varies from -40 °C to 80 °C. Moreover, the rising-time and falling-time increase of the output pulse are both less than 3 μs after 240 hours of the accelerated high temperature aging operations.

A New Single-Source Nine-Level Quadruple Boost Inverter (NQBI) for PV Application

Multi-level inverters (MLIs) with switched capacitors are becoming popular due to their utilization in AC high-voltage applications as well as in the field of renewable energy. To achieve the required magnitude of output voltage, the switched capacitor (SC) technique employs a lesser number of DC sources in accordance with the voltage across the capacitor. Designing an efficient high-gain MLI with fewer sources and switches needs a rigorous effort. This paper introduces a prototype of a nine-level quadruple boost inverter (NQBI) topology powered by one solar photo-voltaic source using fewer capacitors, switches, and diodes when compared to the other SC-MLIs topology. The suggested NQB inverter produces nine levels of voltage in its output by efficiently balancing the voltages of the two capacitors. The various SC-MLIs are compared in order to highlight the benefits and drawbacks of the proposed nine-level quadruple boost inverter (NQBI) topology. To validate the efficacy of the proposed solar photovoltaic based NQBI without grid connection, detailed experimental results are presented in a laboratory setting under various test conditions.

Modified Selective Harmonics Mitigation PWM for a Switched Diode Multilevel Inverter

A modified selective harmonic mitigation (SHM) technique for multilevel inverters considering the RMS output voltage magnitude is presented. The harmonic contents in the output voltage of these inverters must satisfy the specified grid code requirement standards. In conventional SHM techniques, the firing angles of the multilevel inverters have been derived by taking into account grid code harmonic reduction standards. When the multi-level inverters are driven with these firing pulses generated, it results in reduction of the magnitude of the inverter output voltage. In order to overcome this issue of output voltage reduction, the modified SHM optimization problem includes another constraint on the RMS output voltage limits, which results in different set of firing angles. This facilitates the use of firing angles, which takes into account the grid code standards of harmonic mitigation without compromising the value of the RMS output voltage of the inverters. The proposal has been simulated and validated in MATLAB Simulink and the experimental results are obtained for a single-phase seven level inverter with Silicon made semiconductor switches. By using the proposed method, output voltage THD (upto 40th harmonics were considered) of 5.9% was obtained, which is well below the harmonic standards specified by EN 50160.

Design and Simulation of an Isolated Seven Level Three Phase Inverter

Abstract: This paper proposes a seven level three phase inverter with PWM control scheme for better performance and magnitude control of output voltage. This proposed inverter offers a proper isolation between load and inverter circuit and different phases also. This inverter is capable of generating waveforms independently for different phases. By changing the reference signal frequency output frequency can be changed which is capable to make the system of variable frequency. Use of reverse voltage topology has increased the magnitude of output voltage. Proper application of diode makes the unidirectional switch bidirectional and decreases the number of switches. Keywords: Pulse width modulation, multi-level topology, bi-directional switches, isolation system

Elimination of circulating current in parallel operation of single phase inverter using droop controller

This paper presents the control strategy for parallel operation of an inverter to eliminate DC & AC circulating current. This paper also analyses the cross-current between parallel connected inverter due to the difference in output voltage magnitudes of inverters, the phase difference of inverter output voltages and difference in DC offsets present in inverter output voltages. The circulating current flows between inverters due to DC-offset voltage and fluctuation of AC output voltages. This strategy uses the fundamental voltage and phase droop scheme to allow the inverters to share their load currents and uses a DC-offset droop scheme in order to eliminate DC circulating current. AC component of current is divided into two parts i.e. an active component of the current Ip and a reactive component of the current Iq. These two components of AC currents are used to eliminate AC circulating current. The validity of the proposed control strategy is investigated through MATLAB simulation and the results obtained satisfactorily.

Adaptive and Robust Operation with Active Fuzzy Harvester under Nonstationary and Random Disturbance Conditions.

The objective of this paper is to amplify the output voltage magnitude from a piezoelectric vibration energy harvester under nonstationary and broadband vibration conditions. Improving the transferred energy, which is converted from mechanical energy to electrical energy through a piezoelectric transducer, achieved a high output voltage and effective harvesting. A threshold-based switching strategy is used to improve the total transferred energy with consideration of the signs and amplitudes of the electromechanical conditions of the harvester. A time-invariant threshold cannot accomplish effective harvesting under nonstationary vibration conditions because the assessment criterion for desirable control changes in accordance with the disturbance scale. To solve this problem, we developed a switching strategy for the active harvester, namely, adaptive switching considering vibration suppression-threshold strategy. The strategy adopts a tuning algorithm for the time-varying threshold and implements appropriate intermittent switching without pre-tuning by means of the fuzzy control theory. We evaluated the proposed strategy under three realistic vibration conditions: a frequency sweep, a change in the number of dominant frequencies, and wideband frequency vibration. Experimental comparisons were conducted with existing strategies, which consider only the signs of the harvester electromechanical conditions. The results confirm that the presented strategy achieves a greater output voltage than the existing strategies under all nonstationary vibration conditions. The average amplification rate of output voltage for the proposed strategy is 203% compared with the output voltage by noncontrolled harvesting.

A Six-Arm Symmetrical Six-Phase Hybrid Modular Multilevel Converter With Unidirectional Current Full-Bridge Submodules

Multiphase converter complexity is one of the concerns that restrict the widespread utilization of multiphase machines. One of the developmental trends to alleviate the converter complexity is reducing passive and active component counts. In this regard, several examples have been reported in the literature for modular multilevel converter (MMC) topologies with a reduced component count for six-phase medium-voltage motor drives. A three-leg nine-arm MMC (9A-MMC) with half-bridge submodules has been proposed with a 25% reduction in the number of employed components, compared to the standard six-leg twelve-arm MMC, however with limited output voltage magnitude. To enhance the dc-link voltage utilization, hybrid designs of the 9A-MMC have been recently suggested with a combination of half-bridge and bidirectional/unidirectional current full-bridge submodules (FB-SMs) in each leg. For further structural reduction, this article proposes a two-leg six-arm hybrid MMC with half-bridge and unidirectional current FB-SMs for symmetrical six-phase machines. The proposed architecture achieves a further reduction in component count, reducing the implementation complexity without compromising the delivered power. Detailed illustrations, analysis, and operational concepts of the proposed topology are presented. To quantify its pros and cons, the proposed topology is assessed versus other existing alternatives in the literature. Simulation and experimental results are presented to validate the concept and effectiveness of the proposed architecture.