To see the other types of publications on this topic, follow the link: Unipolar and bipolar modulation, voltage stress.
Journal articles on the topic 'Unipolar and bipolar modulation, voltage stress'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 41 journal articles for your research on the topic 'Unipolar and bipolar modulation, voltage stress.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Eya, Candidus U., Ayodeji Olalekan Salau, Sepiribo Lucky Braide, S. B. Goyal, Victor Adewale Owoeye, and Oluwafunso Oluwole Osaloni. "Assessment of Total Harmonic Distortion in Buck-Boost DC-AC Converters using Triangular Wave and Saw-Tooth based Unipolar Modulation Schemes." WSEAS TRANSACTIONS ON POWER SYSTEMS 17 (November 8, 2022): 324–38. http://dx.doi.org/10.37394/232016.2022.17.33.
Full textAbstract:
This paper presents an assessment of the levels of total harmonic distortion (THD) in buck-boost DC-AC converters using triangular wave and saw-tooth unipolar based-modulation schemes. This paper seeks to identify a better technique for mitigating the total harmonic distortion on buck-boost DC-AC converters under unipolar carrier-based modulation schemes. This was achieved by subjecting the buck-boost DC-AC converter under triangular wave-based and saw-tooth based-unipolar modulation schemes. The voltage and current output of the buck- boost DC-AC converter under each scheme was analysed using a power GUI Fast Fourier Transform (FFT) analytical tool resident in the MATLAB Simulink environment unlike with the conventional scheme of computing the percentage of THD. The test system was obtained by a combination of DC-DC buck-boost converter, H-bridge based-insulated unipolar gate transistors, and a logic control unit. It was realized that THD of 0.2865%, peak output voltage of 294.1V and current of 9.805A were obtained by using the saw-tooth based-unipolar modulation scheme, whereas a THD of 0.1479%, peak output voltage of 297.4V and current of 9.53A were obtained by using the triangular wave based-bipolar modulation scheme on the same Buck-boost DC-AC converter circuit. The results imply a high power factor utilization and low power loss in the triangular wave based-unipolar modulation scheme compared to the saw-tooth based-unipolar modulation technique for improving the performance characteristics of the buck-boost converter system. This study showed that power drives and heavy load machines based-power electrical loads are required to use the saw-tooth based-unipolar modulation (STBUM) scheme for high current and low THD%, whereas sensitive power electrical loads such as hospital equipment and communication industries based-power electronic devices are required to use the triangular wave-based unipolar modulation (TWBUM) scheme due to low current and THD%.
2
Li, Yue, Hailong Yu, Chuan Jiang, and Yong Jin. "Analysis of Control Strategy of Arc Plasma Power Supply Inverter Module." Electronics 12, no. 21 (2023): 4400. http://dx.doi.org/10.3390/electronics12214400.
Full textAbstract:
The inverter module serves as a critical component in the conversion of electrical energy within arc plasma power sources, exerting a profound influence on the overall performance and stability of the power supply. Consequently, the meticulous design and precise control of the inverter module are of paramount importance in ensuring the effective operation and application of arc plasma power sources. This paper introduces a dual-closed-loop control system, integrating a voltage outer loop with a current inner loop, as the cornerstone of its inverter module design. It also undertook a comprehensive comparative analysis of various voltage-control strategies, encompassing four control methods (PI, PID, PR, QPR) and two modulation techniques (bipolar modulation and unipolar, carrier-based modulation) under diverse operating conditions. Additionally, simulation experiments were conducted on a prototype 10 kW inverter module using the Matlab/Simulink simulation platform, with evaluation criteria including waveform tracking performance, voltage waveform distortion rate, and steady-state error. The results indicate that in low-frequency operating conditions, the voltage-control strategy employing QPR control plus unipolar, carrier-based modulation, and in high-frequency operating conditions, the voltage-control strategy utilizing PI control plus unipolar, carrier-based modulation exhibited superior waveform tracking performance. The waveform distortion rates were measured at below 0.47% and 4.2%, respectively, aligning perfectly with the stringent standards of IEEE 519. This research provides valuable theoretical support and practical guidance for future engineering endeavors in the field of inverters.
3
Deb, Arkadeep, Jose Ortiz-Gonzalez, Mohamed Taha, Saeed Jahdi, Phillip Mawby, and Olayiwola Alatise. "Impact of Turn-Off Gate Voltage and Temperature on Threshold Voltage Instability in Pulsed Gate Voltage Stresses of SiC MOSFETs." Materials Science Forum 1091 (June 5, 2023): 61–66. http://dx.doi.org/10.4028/p-lidhbt.
Full textAbstract:
Bias temperature instability (BTI) in SiC MOSFETs has come under significant academic and industrial research. Threshold voltage (VTH) shift due to gate voltage stress has been demonstrated in several studies investigating gate oxide reliability in SiC MOSFETs. Results have shown positive.VTH shift occurs due to electron trapping (PBTI), and negative VTH shift occurs due to hole trapping (NBTI). In this paper, VTH shift is studied for unipolar and bipolar gate pulses with frequencies ranging from 1Hz to 100 kHz. The turn-OFF voltage for the unipolar VGS pulse is 0 V. In the case of the bipolar VGS pulses, two turn-OFF voltages are investigated, namely VGS-OFF = -3V and VGS-OFF= -5V. VTH shift is measured after 1000 seconds with recovery times in the range of 20 milliseconds, and preconditioning is performed before VTH measurement. These measurements have been performed at 25°C and 150°C on a commercially available SiC Planar MOSFET and a SiC Trench MOSFET. The results show that -3 V is enough for de-trapping sufficient electrons while -5V results in increased NBTI, which is accelerated by higher temperatures.
4
Jia, Moqi. "Research on offshore DC wind power circuit." Journal of Physics: Conference Series 2378, no. 1 (2022): 012023. http://dx.doi.org/10.1088/1742-6596/2378/1/012023.
Full textAbstract:
Abstract This paper studies the offshore DC wind power technology, to explore how to reasonably transmit and use the electrical energy generated by the offshore wind generator, to obtain a more optimized circuit model of offshore DC wind power technology. This paper mainly discusses the process of voltage conversion, inverter, rectification and output of appropriate three-phase AC voltage in the process of ac transmission from HVDC offshore wind turbine. According to the “π” equivalent circuit principle, the paper compares HVDC transmission mode with HVDC transmission mode, and compares the harmonic distortion rate of unipolar modulation and bipolar modulation in pulse width modulation through analog circuit, determines the final circuit model and obtains the simulation result diagram.
5
Aihsan, M. Z., A. M. Yusof, Hasliza A. Rahim, et al. "Comparative investigations on different types of inductors in single-phase inverter." Journal of Physics: Conference Series 2107, no. 1 (2021): 012051. http://dx.doi.org/10.1088/1742-6596/2107/1/012051.
Full textAbstract:
Abstract This article organized in two sections where it compares the performance of single-phase inverters using various types of inductors with differences modulation technique of pulse width modulation (PWM). Not all inductors perform the same function, even the inductance value is the same. The study will investigate the capability of each inductor on its performance to convert the unfiltered AC voltage into filtered sinusoidal AC voltage. The drum core and toroidal core inductors were used in this investigation. For both inductors, the performance will be analyzed based on Bipolar and Unipolar switching schemes in a single unit H-bridge circuit. The validation of results are through experimental assessment only and it will be evaluating the shape of sinusoidal AC voltage and the content of total harmonics distortion in the AC voltage for both inductors.
6
Ispirli, Mehmet Murat, Özcan Kalenderli, Florian Seifert, Michael Rock, and Bülent Oral. "The Effect of DC Voltage Pre-Stress on the Breakdown Voltage of Air under Composite DC and LI Voltage and Test Circuit: Design and Application." Energies 15, no. 4 (2022): 1353. http://dx.doi.org/10.3390/en15041353.
Full textAbstract:
The use of HVDC systems is increasing in number due to technological innovations, increasing power capacity and increasing customer demand. The characteristics of insulation systems under composite DC and LI voltage must be examined and clarified. In this study, firstly, experimental circuits were designed to generate and measure composite DC and LI high voltage using a simulation program. The coupling elements used were chosen according to simulation results. Afterward, experimental circuits were established in the laboratory according to the simulation results of the designed experimental circuit. Then, breakdown voltages under composite DC and LI voltage for less uniform and non-uniform electric fields were measured with four different electrode systems for positive and negative DC voltage pre-stresses with different amplitudes. The 50% breakdown voltage was calculated using the least-squares method. Finally, 3D models were created for the electrode systems used in the experiments using the finite element method. The efficiency factors of electrode systems calculated with the FEM results were correlated with the experimental breakdown voltage results. Thus, the breakdown behavior of air under bipolar and unipolar composite voltages (CV) was investigated. In conclusion, the experimental results showed that very fast polarity change in bipolar CV causes higher electrical stress compared to unipolar CV.
7
Mashkin, A. V., and S. B. Fedotovsky. "Assesment of dynamic losses in power switches of autonomous inverters with different modulation algorithms." Vestnik MGTU 23, no. 4 (2020): 326–34. http://dx.doi.org/10.21443/1560-9278-2020-23-4-326-334.
Full textAbstract:
When designing an automated electric drive, it is required to provide the necessary quality indicators of speed control as much as possible with the lowest energy losses in it. Assessment of dynamic losses in power semiconductor switches of autonomous voltage inverters (AVI) is due to the need to select optimal control algorithms for them in order to increase energy efficiency in frequency-controlled asynchronous electric drive systems. To solve the set tasks, the method of mathematical modeling has been used. With the help of the developed program, an assessment of the dynamic losses in a high-speed electric drive during its operation in a steady state has been made. At a typical modulation frequency f = 6,000 Hz, which with scalar control algorithms provides a sufficient degree of approximation of the generated phase voltage envelopes to a sinusoidal form, and the use of pulse-width control (WIR) algorithms, significant dynamic losses are observed in the switches of an autonomous voltage inverter. In the course of using the WID algorithms, an accurate approximation of the sinusoidal shape is not required, which makes it possible to reduce the modulation frequency and, as a consequence, reduce the amount of dynamic losses in the AVI keys. Therefore, a comparative assessment of dynamic losses has been carried out for the scheme of a classic three-phased AVI using the algorithms of unipolar and bipolar pulse-width control. The obtained simulation results have shown that the unipolar WID algorithm is more energy-saving compared to the bipolar WID algorithm when used in high-speed electric drives.
8
Alhamrouni, Ibrahim, N. Zainuddin, Mohamed Salem, Nadia H. A. Rahman, and Lili Awalin. "Design of single phase inverter for photovoltaic application controlled with sinusoidal pulse width modulation." Indonesian Journal of Electrical Engineering and Computer Science 15, no. 2 (2019): 620. http://dx.doi.org/10.11591/ijeecs.v15.i2.pp620-630.
Full textAbstract:
<p>The application of fossil fuels likes coal, oil and gas gives the enormous environmental impact and hazardous effects to the earth. Hence, renewable energy has become the most tremendously friendly methods to generate the electricity without pollution and emissions. Inverter is a power electronics device which is used to convert Direct Current (DC) into Alternating Current (AC). The conventional inverter no longer fulfills the requirement of reducing harmonic distortions plus it causes global warming and greenhouse effect. For increasing the efficiency and reliability of the system, the PV inverter becomes a vital part in the conversion of DC to AC output. This research thus presents a single phase photovoltaic inverter controlled with sinusoidal pulse-width-modulation (SPWM) and low pass filter connection between the inverter and the utility grid to reduce the harmonics due to intermittent nature of the renewable energy sources. Unipolar and Bipolar switching scheme are applied to control the magnitude and frequency of output voltage and result of both unipolar and bipolar are compared. The simulation of the proposed technique is executed by using Matlab/Simulink.</p>
9
Alam, Aftab, Junaid Akhtar, Surendra Kumar, and Brij Mohan Prasad. "Design of SPWM Converter for Improving the Performance of Hybrid Electric Vehicles." International Journal of Microsystems and IoT 2, no. 6 (2024): 968–76. https://doi.org/10.5281/zenodo.13255048.
Full textAbstract:
The interest has grown in Hybrid Electric Vehicles (HEVs) because of the worries over environmental pollution and fuel consumption. The main components of an HEV are the power converter, electric motor, storage system which may be a battery, ultracapacitor, etc. and the internal combustion engine (ICE). A three phase inverter changes fixed dc voltage into ac voltage whose magnitude and frequency can be obtained as required. Power electronics is an empowering technology which helps in development of such an inverter which can be utilized for many purposes. Adjustable output voltage and frequency can be got from a number of pulse width modulation (PWM) methods. Sinusoidal Pulse Width Modulation (SPWM) is a mostly used method of Pulse Width Modulation. This paper focuses on the development of Sinusoidal pulse width modulation inverter using SPWM technique as SPWM has the advantages of lesser harmonics in the output voltage. The concept of unipolar and bipolar modulation is illustrated. Simulation of SPWM inverter has been presented to analyze the output line voltage, phase voltage and SPWM technique. Simulation of SPWM inverter has been done without and with filter and FFT analysis has been done to find the total harmonic distortion (THD) in the output line voltage. Hardware development of SPWM inverter has been done. dSPACE controller has been used for the generation of the firing pulses. Finally experimental results have been presented which include the waveforms of the firing pulses, output line voltage and output phase voltage.
10
Zhang, Dezhen, Zhen Ouyang, Wei Ma, Xiang Shen, Jinwei Lv, and Yangxin Zou. "Modulation of Wide Voltage Range Interface DC-DC Converter in DC Distribution System." American Journal of Electrical Power and Energy Systems 13, no. 2 (2024): 21–31. http://dx.doi.org/10.11648/j.epes.20241302.11.
Full textAbstract:
Bipolar DC distribution systems rely on various power sources like photovoltaics and distributed energy storage, each with its unique voltage characteristics. To accommodate these fluctuations, interface converters must adjust over a wide voltage range. The bipolar non-isolated DC-DC converter emerges as a promising solution due to its versatile modulation capabilities, reduced switch voltage stress, and cost-effectiveness. This article explores how wide voltage range regulation is achieved in bipolar DC-DC converters interfacing with bipolar DC power grids. It delves into the operational strategies and modulation techniques employed, ensuring stable output despite varying input voltages. Design considerations and challenges associated with implementing such converters are also discussed. An experimental platform was constructed to validate the proposed methodology. Through rigorous testing and analysis, the effectiveness of the topology&apos;s operation mode was confirmed. Real-world data from the experimental setup provided insights into the converter&apos;s performance under different operating conditions, supporting its applicability for bipolar DC distribution systems. In summary, this article provides a comprehensive examination of wide voltage range regulation in bipolar DC-DC converters, highlighting their potential to enhance efficiency and reliability in bipolar DC power grids. Through theoretical discussions and practical validation, it contributes to the advancement and adoption of these converters in modern energy systems.
11
Mohd Azhar, Aina Suhailah, Maaspaliza Azri, Wahidah Abd Halim, Md Hairul Nizam Talib, Zulhani Rasin, and Mohd Fayzul Mohammed. "Hysteresis current control for single-phase transformerless inverter." International Journal of Applied Power Engineering (IJAPE) 14, no. 1 (2025): 1. https://doi.org/10.11591/ijape.v14.i1.pp1-10.
Full textAbstract:
The total harmonic distortion (THD) of grid current and leakage current are significant for transformerless inverters, as they impact power quality, efficiency, and compliance with grid codes. Monitoring and minimizing these currents ensure safe and reliable grid integration of photovoltaic (PV) systems while reducing electromagnetic interference. Therefore, in this paper, the analysis THD of grid current and leakage current is described. The bipolar pulse width modulation (BPWM) technology provides a stable common-mode voltage (200 V), fewer leakage currents (&lt; 30 mA), and better system efficiency, compared to the unipolar pulse width modulation (UPWM) technique. To ensure the inverter complies with the IEC 61000-3-2 class C (THDi &lt; 5%), the current control strategy should be considered during the design of the transformerless inverter. Therefore, this paper presents an implementation and evaluation of the bipolar hysteresis current control (BHCC) technique. In comparison to the BPWM technique, the BHCC technique delivers lower leakage current (0.007274 A), reduced grid current harmonic distortion (1.81%), and increased efficiency.
12
Mohd, Azhar Aina Suhailah, Maaspaliza Azri, Halim Wahidah Abd, Md Hairul Nizam Talib, Zulhani Rasin, and Mohd Fayzul Mohammed. "Hysteresis current control for single-phase transformerless inverter." International Journal of Applied Power Engineering (IJAPE) 14, no. 1 (2025): 1–10. https://doi.org/10.11591/ijape.v14.i1.pp1-10.
Full textAbstract:
The total harmonic distortion (THD) of grid current and leakage current are significant for transformerless inverters, as they impact power quality, efficiency, and compliance with grid codes. Monitoring and minimizing these currents ensure safe and reliable grid integration of photovoltaic (PV) systems while reducing electromagnetic interference. Therefore, in this paper, the analysis THD of grid current and leakage current is described. The bipolar pulse width modulation (BPWM) technology provides a stable common-mode voltage (200 V), fewer leakage currents (< 30 mA), and better system efficiency, compared to the unipolar pulse width modulation (UPWM) technique. To ensure the inverter complies with the IEC 61000-3-2 class C (THDi < 5%), the current control strategy should be considered during the design of the transformerless inverter. Therefore, this paper presents an implementation and evaluation of the bipolar hysteresis current control (BHCC) technique. In comparison to the BPWM technique, the BHCC technique delivers lower leakage current (0.007274 A), reduced grid current harmonic distortion (1.81%), and increased efficiency.
13
Osipov, A. V. "Synthesis of two-frequency current by a parallel-to-series resonant LCLC-converter with multiple pulse-width modulation." Proceedings of Tomsk State University of Control Systems and Radioelectronics 24, no. 1 (2021): 75–82. http://dx.doi.org/10.21293/1818-0442-2021-24-1-75-82.
Full textAbstract:
The methods to form a two-frequency inductor current in a resonant converter with multiple pulse-width modulation for systems of induction heating of complex surface shape bodies are considered. The study of the methods used to form and to regulate the frequency components of the inductor current is carried out. The approaches to assess the energy efficiency of two frequency converters are proposed and its assessment is carried out for multiple PWM by the values of power factors and overall power. It is shown that the high-frequency harmonic is formed by two components: the one that is generated by multiple modulation and the one contained in the rectangular voltage of low frequency, the latter significantly affects the energy characteristics. The advantages in terms of energy of bipolar PWM over unipolar PWM are shown
14
Park, HyunHo. "ANN Controller Based Single phase Inverter in Smart City." International Transactions on Electrical Engineering and Computer Science 2, no. 2 (2023): 60–69. http://dx.doi.org/10.62760/iteecs.2.2.2023.51.
Full textAbstract:
Solar-grid integration is a method for incorporating large amounts of photovoltaic (PV) supply to the grid. Advanced inverter technology, smart grids technology, islanding detection technology, solar-grid forecasting technology, grid-plant protection technology and are all part of solar-grid synchronization technology. Many methods are used to control inverters, including sinusoidal pulse width modulation, selective harmonic suppression pulse width modulation, space vector width modulation. Among control methods, pulse width modulation is the most popular. PWM inverters are used for two different switching techniques: bipolar and unipolar. The primary goal of this paper is to create an inverter that will convert a solar DC power source to an AC power source that can be used to power a load or connected directly to the utility grid. In this work, the control of inverter output voltage is done without the need for any user intervention, but only with the intervention of an AI technique, and it is compared to existing methods.
15
Kwon, So-Yeon, Woon-San Ko, Jun-Ho Byun, Do-Yeon Lee, Hi-Deok Lee, and Ga-Won Lee. "The Switching Characteristics in Bilayer ZnO/HfO2 Resistive Random-Access Memory, Depending on the Top Electrode." Electronic Materials 5, no. 2 (2024): 71–79. http://dx.doi.org/10.3390/electronicmat5020006.
Full textAbstract:
In this study, the bipolar switching behaviors in ZnO/HfO2 bilayer resistive random-access memory (RRAM), depending on different metal top electrodes (TE), are analyzed. For this purpose, devices with two types of TE–TiN/Ti and Pd, which have varying oxygen affinities, are fabricated. X-ray diffraction (XRD) analysis shows that ZnO has a hexagonal wurtzite structure, and HfO2 exhibits both monoclinic and orthorhombic phases. The average grain sizes are 10.9 nm for ZnO and 1.55 nm for HfO2. In regards to the electrical characteristics, the I–V curve, cycling test, and voltage stress are measured. The measurement results indicate that devices with TiN/Ti TE exhibit lower set and higher reset voltage and stable bipolar switching behavior. However, a device with Pd TE demonstrates higher set and lower reset voltage. This phenomenon can be explained by the Gibbs free energy of formation (∆Gf°). Additionally, the Pd TE device shows unstable bipolar switching characteristics, where unipolar switching occurs simultaneously during the cycling test. This instability in devices with Pd TE could potentially lead to soft errors in operation. For guaranteeing stable bipolar switching, the oxygen affinity of material for TE should be considered in regards to ZnO/HfO2 bilayer RRAM.
16
Janardhan, G., N. N. V. Surendra Babu, and G. N. Srinivas. "Single phase transformerless inverter for grid connected photovoltaic system with reduced leakage current." Electrical Engineering & Electromechanics, no. 5 (September 6, 2022): 36–40. http://dx.doi.org/10.20998/2074-272x.2022.5.06.
Full textAbstract:
Introduction. Transformerless inverters are of vital importance in the field of grid connected solar photovoltaic systems offering higher efficiency than the conventional one. i.e., using transformer. General grid connected inverters are constituting of transformers requires more area besides the loss in them. Problem. Eliminating transformers can cause leakage current due to the variation of common mode voltage which in turn due to parasitic capacitance effect. Research literature in transformerless inverters has addressed the problems of common mode leakage current issues by offering the study of different inverter topologies like H4, H5, H6 and HERIC etc. utilizing variety of modulation strategies like unipolar, bipolar pulse width modulations. Goal. The paper significantly presents a new transformerless inverter topology, analyzes common mode voltage and leakage current behavior of the system. The simulation is carried out for comparing the leakage current profiles with other transformerless inverter topologies in literature. Novelty. This paper gives an impression of the efficient transformerless inverter for grid connected photovoltaic system. Results. The various inverter topologies full bridge with different pulse width modulation techniques are analyzed and to determine the common mode voltages and leakage currents.
17
Sundaresan, Siddarth, Ranbir Singh, and R. Wayne Johnson. "SILICON CARBIDE “SUPER” JUNCTION TRANSISTORS OPERATING AT 500 °C." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, HITEC (2012): 000162–66. http://dx.doi.org/10.4071/hitec-2012-wa15.
Full textAbstract:
1200 V/ 3 mm2 active-area SiC “Super” Junction Transistors (SJTs) display current gains as high as 88 and majority carrier operation up to 250 °C. The SJT operation shifts from purely unipolar to bipolar-mode at temperatures ≥ 300 °C. The leakage currents at a blocking voltage of 1200 V remain below 100 μA, even at 325 °C. Temperature-independent turn-on and turn-off times &lt; 15 ns are measured up to 250 °C. A short-circuit withstand time of 22 μs at VDS=800 V, and a single-pulse avalanche energy of 20.4 mJ are measured. No degradation of the blocking I-V characteristics was observed after a 934 hour repetitive avalanche stress test.
18
G., Janardhan, N. V. Surendra Babu N., and N. Srinivas G. "Single phase transformerless inverter for grid connected photovoltaic system with reduced leakage current." Electrical Engineering & Electromechanics, no. 5 (September 7, 2022): 36–40. https://doi.org/10.20998/2074-272X.2022.5.06.
Full textAbstract:
<strong><em>Introduction</em></strong><em>. Transformerless inverters are of vital importance in the field of grid connected solar photovoltaic systems offering higher efficiency than the conventional one. i.e., using transformer. General grid connected inverters are constituting of transformers requires more area besides the loss in them. <strong>Problem</strong>. Eliminating transformers can cause leakage current due to the variation of common mode voltage which in turn due to parasitic capacitance effect. Research literature in transformerless inverters has addressed the problems of common mode leakage current issues by offering the study of different inverter topologies like H4, H5, H6 and HERIC etc. utilizing variety of modulation strategies like unipolar, bipolar pulse width modulations. <strong>Goal</strong>. The paper significantly presents a new transformerless inverter topology, analyzes common mode voltage and leakage current behavior of the system. The simulation is carried out for comparing the leakage current profiles with other transformerless inverter topologies in literature. <strong>Novelty</strong>. This paper gives an impression of the efficient transformerless inverter for grid connected photovoltaic system. <strong>Results</strong>. The various inverter topologies full bridge with different pulse width modulation techniques are analyzed and to determine the common mode voltages and leakage currents.</em>
19
Biswas, Mohua, Shuvra Prokash Biswas, Md Rabiul Islam, Md Ashib Rahman, Kashem M. Muttaqi, and S. M. Muyeen. "A New Transformer-Less Single-Phase Photovoltaic Inverter to Improve the Performance of Grid-Connected Solar Photovoltaic Systems." Energies 15, no. 22 (2022): 8398. http://dx.doi.org/10.3390/en15228398.
Full textAbstract:
Photovoltaic (PV) energy systems have found diverse applications in fulfilling the increasing energy demand worldwide. Transformer-less PV inverters convert the DC energy from PV systems to AC energy and deliver it to the grid through a non-isolated connection. This paper proposes a new transformer-less grid-connected PV inverter. A closed-loop control scheme is presented for the proposed transformer-less inverter to connect it with the power grid. The proposed transformer-less inverter reduces extra leakage current and holds the common-mode voltage at a constant point. To eliminate extra leakage current, as well as achieve constant common-mode voltage, a midpoint clamping method is utilized to operate the inverter. The proposed transformer-less inverter is formed of seven insulated gate bipolar transistors (IGBTs) employing a unipolar sinusoidal pulse width modulation (SPWM) technique for switching purposes. An LCL filter is employed to reshape the two-level inverter output voltage and current to obtain closer sinusoidal waveforms. The output voltage and current total harmonic distortion (THD) of the proposed transformer-less inverter were found to be 1.25% and 0.94%, respectively, in the grid-connected mode. The leakage current elimination mechanism with the proposed transformer-less inverter is deeply analyzed in this paper. The performances of the proposed transformer-less inverter were evaluated with MATLAB/Simulink simulation and validated in a laboratory scale experiment.
20
Luarte, Alejandro, Pablo Cisternas, Ariel Caviedes, et al. "Astrocytes at the Hub of the Stress Response: Potential Modulation of Neurogenesis by miRNAs in Astrocyte-Derived Exosomes." Stem Cells International 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/1719050.
Full textAbstract:
Repetitive stress negatively affects several brain functions and neuronal networks. Moreover, adult neurogenesis is consistently impaired in chronic stress models and in associated human diseases such as unipolar depression and bipolar disorder, while it is restored by effective antidepressant treatments. The adult neurogenic niche contains neural progenitor cells in addition to amplifying progenitors, neuroblasts, immature and mature neurons, pericytes, astrocytes, and microglial cells. Because of their particular and crucial position, with their end feet enwrapping endothelial cells and their close communication with the cells of the niche, astrocytes might constitute a nodal point to bridge or transduce systemic stress signals from peripheral blood, such as glucocorticoids, to the cells involved in the neurogenic process. It has been proposed that communication between astrocytes and niche cells depends on direct cell-cell contacts and soluble mediators. In addition, new evidence suggests that this communication might be mediated by extracellular vesicles such as exosomes, and in particular, by their miRNA cargo. Here, we address some of the latest findings regarding the impact of stress in the biology of the neurogenic niche, and postulate how astrocytic exosomes (and miRNAs) may play a fundamental role in such phenomenon.
21
Ansh and Mayank Shrivastava. "Superior resistance switching in monolayer MoS2 channel-based gated binary resistive random-access memory via gate-bias dependence and a unique forming process." Journal of Physics D: Applied Physics 55, no. 8 (2021): 085102. http://dx.doi.org/10.1088/1361-6463/ac3281.
Full textAbstract:
Abstract Resistance switching (RS) in 2D molybdenum disulfide (MoS2) was recently discovered. Since the discovery, many reports demonstrating MoS2 resistive random-access memory (RRAM) with synapse-like behavior have been published. These reports strongly justify applications of MoS2 RRAM in neuromorphic hardware as well as an alternative to conventional binary memories. In this work, we unveil the effect of RS, induced by current–voltage hysteresis cycles across CVD-grown monolayer MoS2-based gated RRAM, on its transistor’s electrical and reliability characteristics. A unique gate voltage dependence on the RS is identified which has a remarkable impact on the switching performance of MoS2 RRAM. RS behavior was found to be significantly dependent on the charge conduction in the channel. Moreover, we have shown a potential device-forming event when MoS2-gated RRAMs were subjected to a steady-state electrical stress. Both hysteresis and steady-state electrical stress were found to disturb the transistor action of these gated RRAMs, which can in fact be used as a signature of RS. Interestingly, current–voltage hysteresis resulted in unipolar RS, whereas steady-state electrical stress before RS measurement led to bipolar RS. Moreover, successive stress cycles of such electrical stress lead to multiple resistance states, a behavior similar to synaptic properties such as long-term potentiation and long-term depression, typically found in memristors. We find that the charge transport mechanism dominant in the MoS2 FET, in conjunction with steady-state stress-induced device forming, determine the extent of RS induced in thes MoS2-based gated RRAMs. Finally, on the basis of insights developed from the dependence on the charge transport mechanism and steady-state stress-induced forming of the MoS2 channel, we propose a certain steady-state electrical stress condition which can be used as a ‘forming’ process, employed prior to the use of MoS2-based binary RRAMs for improved switching performance.
22
Chen, Junsheng, and Peng Wang. "Impacts of Bipolar Impulse Parameters on the PDIV of Random-Wound Inverted-Fed Motor Insulation." Energies 18, no. 11 (2025): 2932. https://doi.org/10.3390/en18112932.
Full textAbstract:
The detection of Partial Discharge Inception Voltage (PDIV) is vital for evaluating the insulation performance of random-wound inverter-fed motor stators. However, existing research on the impact of impulse parameters on PDIV patterns and their underlying mechanisms is limited, leading to inadequate guidelines for choosing suitable impulse parameters during PDIV tests of stator insulation under impulsive conditions. This lack of understanding significantly affects the precision of the accuracy of insulation test results for inverter-fed motors. To bridge this gap, this study systematically investigated the influence of key impulse parameters, such as pulse width, dead time, and impulse frequency, on the PDIV test outcomes in enameled wire samples (enameled twisted pairs and pig-tail wires) and random-wound inverter-fed motor stators. A differential bipolar repetitive impulse voltage and a sinusoidal voltage were applied to simulate the pulse-width modulation electrical stress typically experienced by these motors. Results reveal a negative correlation between PDIV test results and pulse width, a positive correlation with dead time, and a weak correlation with impulse frequency. Furthermore, the potential fundamental mechanisms are proposed for the influence of impulse voltage parameters on PDIV characteristics by analyzing the electric field distribution and discharge processes within insulating materials when subjected to impulsive voltages. Based on the experimental conclusion, this study proposes targeted recommendations for revising the current IEC testing standards. These improvements are anticipated to refine stator insulation testing methodologies for inverter-fed motors, ultimately contributing to enhanced insulation reliability in such electric motors.
23
Alexandr, Shavelkin, Mohmed Jasim Jasim Jasim, and Shvedchykova Iryna. "IMPROVEMENT OF THE CURRENT CONTROL LOOP OF THE SINGLE-PHASE MULTIFUNCTIONAL GRID-TIED INVERTER OF PHOTOVOLTAIC SYSTEM." Eastern-European Journal of Enterprise Technologies 6, no. 5 (102) (2019): 14–22. https://doi.org/10.15587/1729-4061.2019.185391.
Full textAbstract:
Improvement of the current control loop of the multifunctional grid-tied inverter of the local object electrical power system is considered. The purpose is ensuring compliance with the quality standards of the grid current in the whole range of its values when connecting the load to the AC distribution grid and the converter unit of the photovoltaic system. The use of relay current controller with combining of unipolar and bipolar modulation in combination with a modified algorithm of switching the inverter switches is proposed. It is shown that at a non-linear load, the jump-like change of the derivative of the inverter reference current leads to a sharp change in the switching frequency of the switches. This leads to the appearance of “splashes” in the grid current, which worsens its harmonic composition at small current values. In the nonlinear reactor with an increase in the inverter current, the “splash” is also caused by changes in the switching frequency of the switches. This takes place in the areas of current growth (fall) due to a change in the reactor inductance. The dependence of the given deviation for the relay controller is established. In the case of a linear reactor, this provides a practically constant switching frequency for the inverter switches. It is proposed to take into account the derivative of the inverter current in the deviation reference of the relay controller. This eliminates an abrupt change in switches switching frequency. The necessity of taking into account the non-sinusoidal grid voltage during the determination of the voltage value at the inverter input is shown. It is proposed to reduce the capacitance of the filter capacitor at the point of common coupling and use of capacitor current coupling. This will improve the quality of the grid current at the non-sinusoidal voltage of the grid. The structure of the current control loop with a relay current controller with the combined modulation and regulation of the reference value of the controller deviation is proposed. Regulation is carried out in accordance with the reference value of the amplitude and the derivative of the inverter current. A mathematical model of the system “grid – grid inverter – load” with a block of determination of power losses in the switches and a nonlinear reactor is developed
24
Mahadik, Nadeemullah, David A. Scheiman, Jeff A. Mittereder та ін. "(Invited) Expansion Behavior of Single BPD Loop Causing Stacking Fault Multiplication in 180 Μm Thick 4H-SiC Epitaxial Layers". ECS Meeting Abstracts MA2024-02, № 36 (2024): 2521. https://doi.org/10.1149/ma2024-02362521mtgabs.
Full textAbstract:
Silicon carbide (4H-SiC) devices with blocking voltage rating up to 3.3 kV have been successfully commercialized [1]. This is due to availability of low cost and low defectivity epitaxial layers with a thickness of up to 30 µm that are need for devices up to 3.3 kV. However, for grid scale and defense applications, higher voltage (10-30 kV) SiC devices such as insulated gate bipolar transistors (IGBTs) are needed. For this, thicker epitaxial layers, ranging from 100 – 250 µm thick, are required withstanding the higher blocking voltage. Such epitaxial layers are prone to formation of basal plane dislocation loops due to a combination of higher thermal stress and lattice mismatch between the lightly doped epitaxial layers and highly doped substrates [2-4]. These BPD loops can expand and form stacking faults (SFs) during device operation, which leads to forward voltage degradation in bipolar devices such as IGBTs as well as higher reverse bias leakage in both unipolar and bipolar devices. This effect will be more severe with the presence of multiple SFs in the device area. In this work, we perform an investigation of a single BPD loop that interacts with several threading mixed dislocations (TMDs) upon carrier injection and creates at least 15 stacking faults. For this work, we used 180 µm thick SiC epitaxial layers with n-doping of 5x1014 cm-3. This was commercially grown on 150 µm 4H-SiC substrates with an ~1µm thick highly n-doped buffer layer. A single BPD loop was identified in the wafer using ultraviolet photoluminescence (UVPL) imaging. High resolution X-ray topography (XRT) of the BPD loop was performed to investigate its formation using Rigaku XRTMicron system with Mo radiation in depth-resolved section geometry with g=11-20 and g=1-100 Bragg conditions. The BPD loop was expanded with carrier injection using 355nm UV excitation, and concurrently imaged with UVPL imaging. A series of successive images were collected for a duration of ~30 mins. This was followed by XRT imaging of the BPD loop after the expansion. From the initial UVPL images, the single BPD loop was observed to have faulted into a single SF, and after the ~30 min exposure, at least 15 SFs were observed from the same region. During the SF expansion, the Si-core partial dislocations bounding the SF interact with several TMDs, including mostly straight as well as tilted TMDs. These interactions form both locked partial dislocation dipoles (PDDs) as well as mobile PDDs, which freely glide as new SFs. It was also observed that an initial BPD partial interacts successively with two tilted TMDs and leaves behind a mixed partial dislocation, which later faults into a new SF. Several other interactions between the expanding BPD partials and TMDs will be presented. From the section XRT images, the BPD loop was found to originate from a single BPD in the substrate with a single interfacial dislocation (ID), and the BPD appeared to loop back towards the substrate/epilayer interface. The other end of the BPD loop did not have an ID. Detailed investigation of the formation and expansion behavior of the BPD loop will be presented. References: [1] D. Xing et. al., pp 1-6, 2020 WiPDA Asia, doi.org/10.1109/WiPDAAsia49671.2020.9360270 [2] N. A. Mahadik, et. al., J. Appl. Phys. 131, 225702, (2022) [3] H. Wang et. al., ECS Trans. 64, 213, (2014) [4] H. Tsuchida et. al., Phys. Status Solidi B 246, 1553 (2009) Figure 1
25
Jones, Matthew C., Junzhe Zha, and Martin J. Humphries. "Connections between the cell cycle, cell adhesion and the cytoskeleton." Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1779 (2019): 20180227. http://dx.doi.org/10.1098/rstb.2018.0227.
Full textAbstract:
Cell division, the purpose of which is to enable cell replication, and in particular to distribute complete, accurate copies of genetic material to daughter cells, is essential for the propagation of life. At a morphological level, division not only necessitates duplication of cellular structures, but it also relies on polar segregation of this material followed by physical scission of the parent cell. For these fundamental changes in cell shape and positioning to be achieved, mechanisms are required to link the cell cycle to the modulation of cytoarchitecture. Outside of mitosis, the three main cytoskeletal networks not only endow cells with a physical cytoplasmic skeleton, but they also provide a mechanism for spatio-temporal sensing via integrin-associated adhesion complexes and site-directed delivery of cargoes. During mitosis, some interphase functions are retained, but the architecture of the cytoskeleton changes dramatically, and there is a need to generate a mitotic spindle for chromosome segregation. An economical solution is to re-use existing cytoskeletal molecules: transcellular actin stress fibres remodel to create a rigid cortex and a cytokinetic furrow, while unipolar radial microtubules become the primary components of the bipolar spindle. This remodelling implies the existence of specific mechanisms that link the cell-cycle machinery to the control of adhesion and the cytoskeleton. In this article, we review the intimate three-way connection between microenvironmental sensing, adhesion signalling and cell proliferation, particularly in the contexts of normal growth control and aberrant tumour progression. As the morphological changes that occur during mitosis are ancient, the mechanisms linking the cell cycle to the cytoskeleton/adhesion signalling network are likely to be primordial in nature and we discuss recent advances that have elucidated elements of this link. A particular focus is the connection between CDK1 and cell adhesion. This article is part of a discussion meeting issue ‘Forces in cancer: interdisciplinary approaches in tumour mechanobiology’.
26
Mohd Sharifuddin, Nuraina Syahira, Nadia M. L. Tan, and Hirofumi Akagi. "Evaluation of a Three-Phase Bidirectional Isolated DC-DC Converter with Varying Transformer Configurations Using Phase-Shift Modulation and Burst-Mode Switching." Energies 13, no. 11 (2020): 2836. http://dx.doi.org/10.3390/en13112836.
Full textAbstract:
This paper presents the performance of a three-phase bidirectional isolated DC-DC converter (3P-BIDC) in wye-wye (Yy), wye-delta (Yd), delta-wye (Dy), and delta-delta (Dd) transformer configurations, using enhanced switching strategy that combines phase-shift modulation and burst-mode switching. A simulation verification using PSCAD is carried out to study the feasibility and compare the efficiency performance of the 3P-BIDC with each transformer configuration, using intermittent switching, which combines the conventional phase-shift modulation (PSM) and burst-mode switching, in the light load condition. The model is tested with continuous switching that employs the conventional PSM from medium to high loads (greater than 0.3 p.u.) and with intermittent switching at light load (less than 0.3 p.u), in different transformer configurations. In all tests, the DC-link voltages are equal to the transformer turns ratio of 1:1. This paper also presents the power loss estimation in continuous and intermittent switching to verify the modelled losses in the 3P-BIDC in the Yy transformer configuration. The 3P-BIDC is modelled by taking into account the effects that on-state voltage drop in the insulated-gate bipolar transistor (IGBTs) and diodes, snubber capacitors, and three-phase transformer copper winding resistances will have on the conduction and switching losses, and copper losses in the 3P-BIDC. The intermitting switching improves the efficiency of the DC-DC converter with Yy, Yd, Dy, and Dd connections in light-load operation. The 3P-BIDC has the best efficiency performance using Yy and Dd transformer configurations for all power transfer conditions in continuous and intermittent switching. Moreover, the highest efficiency of 99.6% is achieved at the light power transfer of 0.29 p.u. in Yy and Dd transformer configurations. However, the theoretical current stress in the 3P-BIDC with a Dd transformer configuration is high. Operation of the converter with Dy transformer configuration is less favorable due to the efficiency achievements of lower than 95%, despite burst-mode switching being applied.
27
Omura, Yasuhisa. "(Invited) Potential of Silicon Oxide Films for Low-Cost and High-Performance Resistive Switching Devices." ECS Meeting Abstracts MA2023-01, no. 33 (2023): 1854. http://dx.doi.org/10.1149/ma2023-01331854mtgabs.
Full textAbstract:
Although resistance switching in transition-metal oxide (TMO) films has been widely studied [1], the physics and chemistry of resistance switching in non-transition-metal oxide (nTMO) films remains under-studied [2]. This must be corrected because inexpensive and chemically stable device configurations are required for the future Internet-of-Things society. It is easily anticipated that the switching electric field of silicon oxide films is apt to be higher than that of TMO films because the dielectric constant of silicon oxide films is smaller than those of the TMO films. However, the use of two-layer stacks like SiOx/hi-k oxide reduces the switching electric field [3]. Therefore, the study of silicon oxide films is still meaningful. Many scientists have recently investigated resistance switching in sputter-deposited silicon oxide films in detail [4,5] because this structure dispenses with the TMO (Fig. 1). Many papers addressed the role of silicon sub-oxide (SiOx) [6] because it is anticipated that the unstable bonds of non-stoichiometric silicon oxide can create degraded, but reversible, conductive paths inside the film. However, it is not yet clear how the SiOx region can trigger resistance switching, how important the SiOx region is, and whether the SiOx region is the only determiner of resistance switching [7] (Figs. 2, 3). The author demonstrated that hot-electron injection from the Si substrate had great potential in triggering resistance switching and lowering the switching voltage of sputter-deposited Si oxide films [5,8]; it was also mentioned that Si precipitates played an important role in realizing repeatable bipolar switching [9] (Fig. 2). Relating to this study, the author also proposed the physical and chemical structure of conductive filaments and their switching behavior based on an analysis of a possibly equivalent circuit model [10] (Fig. 4). However, it was not definitely elucidated why unipolar switching is not easily observed in sputter-deposited silicon oxide films, even though it is not a TMO. Recently, the author performed various Monte Carlo simulations to elucidate the physical and chemical parameters that rule the unipolar switching process in sputter-deposited silicon oxide films. Generations of simple bond breaking, oxygen vacancies, metallic Si sites, and E’’ centers were implemented in the simulation algorithm [8]. All-positive voltage stress mode for both the electroforming process and the reset process will not yield devices with stable, repeatable switching [11]. On the other hand, the all-negative stress mode results in stable, repeatable switching because the recovery of the internal degradation of the Si oxide film is not completed [11] (Fig. 5). This difference stems from the physical asymmetry of the electrode materials (Fig. 1). Though some may consider that silicon oxide films are not preferable to ReRAM devices from the chemical points of view, the theoretical analysis provided by the author in this paper suggests that silicon oxide films can be applied to the ReRAM device. [1] Y. Tokura, Physics Today, vol. 56, pp. 50-55, 2003. [2] T. Yanagida, et al., Sci. Rep., vol. 3, No.1657, pp.1-6, 2013. [3] P. Broqvist and A. Pasquarello, Appl. Phys. Lett., vol. 91, 192905, 2007. [4] J. Yao, et al., Appl. Phys. Lett, vol. 93, pp. 253101-1-253101-3, 2008. [5] R. Yamaguchi, S. Sato, and Y. Omura, Jpn. J. Appl. Phys., vol. 56, pp. 041301-1-041301-6, 2017. [6] A. Mehonic, et al., J. Appl. Phys., vol. 111, pp. 074507-1-074507-9, 2012. [7] Y. Wang, et al., Appl. Phys. Lett., vol.102, pp. 042103-1-042103-5, 2013. [8] Y. Omura, Ind. J. Electrical Eng. & Comput. Sci., vol. 24, pp. 1367-1378, 2021. [9] Y. Omura, R. Yamaguchi, and S. Sato, IEEE Trans. Device Reliab. and Mat. Vol. 17, pp. 561-567 (2017). [10] Y. Omura, ECS J. Solid State Sci. and Technol., vol. 10, pp. 124006-1-124006-10, 2021. [11] Y. Omura, Materials Today Proc., vol. 20, pp. 273-282, 2020; the advanced study will be published in the ECS J. Solid State Sci. and Technol. Figure 1
28
Moorthy, Vijai M., and Viranjay M. Srivastava. "(Digital Presentation) Effect of Active Layer Thickness on Organic Thin-Film Transistors." ECS Meeting Abstracts MA2022-02, no. 35 (2022): 1271. http://dx.doi.org/10.1149/ma2022-02351271mtgabs.
Full textAbstract:
ABSTRACT: Thin-Film Transistors (TFTs) are a substantial technological advancement in recent decades for various applications. The source/drain electrode layer and organic active layer thicknesses of Organic Thin-Film Transistors (OTFTs) should be optimized for better device performance. Organic electronics have been used for a wide range of applications, including flexible screens, smart digital devices, and photovoltaic cells, because of their flexibility and environmental sensitivity. The OTFT has the capability to match the efficiency of thin-film amorphous Silicon transistors, while also being companionable with low-temperature solution/printing-processed fabrication on flexible coupling substrates. The OTFTs are a valuable tool for determining unipolar carrier transport parameters in various situations. In this present research work, authors have utilized the concept of OTFTs in the assessment of bipolar transport properties in active layer blends. It offers a strategy to improve the precision of the assessment. Thereafter, in this this research work, impacts of active layer thickness on physical parameters of OTFT device performance have been realized. The 2D numerical device simulators have been used to examine the proposed OTFT structures. The discussion focuses on the various characteristics and parameters of OTFTs. The OTFTs are transistors that manage electric current flow using organic semiconductors as an active layer. The output and transfer characteristics of various OTFT structures have been used to calculate the performance characteristics of OTFTs. Optimizing the OTFT's organic active layer thickness is critical for high device performance. Both photo-current and photo-responsivity exhibit the same variation trend with increasing organic active layer thicknesses, increasing rapidly for a while and then tending to saturate at high values. The research findings demonstrate the impact of these parameters on device performance and temperature and the need to optimize these variables in the device. The carrier mobility of the high-performance P3HT: PCBM-based OTFT structure was approximately 10 cm2/Vs, and an ON/OFF current ratio of ~103. These results are compatible with those OTFTs fabricated previously. Research Methodology, Results, and Discussions A schematic structure is shown in Figure 1(a) proposed structure top view, and 1(b) a side view of the proposed structure used for simulation. Top-gate OTFT and bottom-gate OTFT geometrical structures have been used in this OTFT. The device's contact resistance, field mobility, and threshold voltage degrade subjected to bias stress. Since top-gate OTFT has a higher device degradation, the authors used bottom-gate OTFT. Due to the distinct properties here in this work the authors utilized conventional materials such as a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as the active layer. A P3HT: PCBM mix is simulated with an electronic device simulator and analyses the variation in active layer thickness that affects the device's performance and the factors that influence the performance of the device in this research work. The output and transfer characteristics of OTFTs have been realized using proper boundary conditions and OTFT physics. The proposed OTFT structures' output and transfer characteristics have been evaluated, and the simulated results show that the optimized structure's drain current (Id, max) is ~2.85 μA. The obtained results show that the device has good transfer and output characteristics at lower gate voltages. With increasing organic active layer thicknesses, both photo-current and photo-responsivity exhibit the same variation trend of increasing sharply at first and then tending to saturate at high values. Conclusion The simulation results examined the performance of devices built with bottom-gate OTFTs. A detailed analysis of the influence of active layer thickness on the OTFT configuration was realized. The device has the advantage of operating at a lower gate voltage, transforming it into a gate efficient control device. The operation at a lower voltage improves electrical stability. The electric field of the OTFT is 1.4x106 V/cm is obtained. The ON/OFF current ratio is higher. The outcomes of this analysis have been optimized and extracted after being tested in various contexts. The findings demonstrated that the suggested concept might be used to make rollable active-matrix displays, nonvolatile memory, sensors, and printed electronic devices. This work also reduces the SCEs and shows more efficient performance than traditional MOSFETs. Together with all application areas, the most important research area has been argued to be the simple manufacturing technique of OTFT with low production cost and non-breakable impacts that can be bent and folded. This device will be optimized with fabrication using these materials in the future, and thereafter, its characteristic will be verified with the simulated results. Figure 1
29
"Performance Evaluation of Induction Motor for Unipolar and Bipolar Pulse Width Modulation Techniques." VOLUME-8 ISSUE-10, AUGUST 2019, REGULAR ISSUE 8, no. 10 (2019): 3626–29. http://dx.doi.org/10.35940/ijitee.j9793.0881019.
Full textAbstract:
Inverter is an interface device between a dc source and ac loads which converts DC voltage to a variable voltage, variable frequency AC voltage. While converting, it introduces harmonics in the output of the system which results in additional heating of induction motors. Hence in order to diminish these harmonics, different techniques are introduced viz. external and internal control techniques in which the latter is more efficient. Out of the all proposed methods, the internal control of inverter which is also called as Pulse Width Modulation (PWM) can be achieved either using unipolar modulation technique or bipolar modulation technique. In this paper, the control circuitry to model unipolar and bipolar modulation methods is simulated and their performance is checked on an induction motor and compared in MATLAB Simulink environment.
30
Khamankar, Rajesh B., Jiyoung Kim, Bo Jiang, and Jack Lee. "Effects of A.C. Stress on Charge and Voltage Decay Rates of PZT Thin Film Capacitors for DRAM Applications." MRS Proceedings 361 (1994). http://dx.doi.org/10.1557/proc-361-263.
Full textAbstract:
ABSTRACTA PZT thin film capacitor displays a reduction in the charge storage density (Qc') after the device has undergone pulsed electrical stress. This changes the charge-voltage relationship for the devices. The effect of this change in the Q-V relationship on the DRAM READ time is described. Measurements of the charge and voltage decay rates have been previously identified as ideal techniques for characterizing signal loss. For the first time the effects of electrical stress on these rates have been studied. While the charge decay rate decreases with an increase in the number of stress cycles for both the bipolar and unipolar stress, the voltage decay rate decreases after unipolar stress but it increases for bipolar stress at lower stress voltages. The implications of these results on the DRAM performance shall be discussed.
31
Polat, Umutcan, and Deniz Yıldırım. "Analysis and Compensation of Dead Time Harmonics Based on Time Compensation Strategy in the Single-Phase Full-Bridge Inverters." Balkan Journal of Electrical and Computer Engineering, January 8, 2024. http://dx.doi.org/10.17694/bajece.1349231.
Full textAbstract:
A short period, called dead time, is implemented to prevent power switching devices from shoot-through in voltage-source inverters (VSI). While adding dead time is required in the switching signals, it also causes negative effects on inverter operation such as distortion at output voltage due to significant number of harmonic components, and reduction in voltage magnitude of fundamental components. Eventually, the negative effects caused by dead time have to be compensated with compensation schemes. Different modulation schemes, which are called unipolar and bipolar switching, can be implemented in VSI, which in return might change the dead time effect. Although analysis of bipolar switching on the dead time effect has been implemented, analysis of unipolar switching is not addressed by most. In this paper, the effect of dead time on unipolar sinusoidal pulse width modulation (SPWM) is analyzed, the principle of the proposed compensation strategy is described in detail and the time compensation method with unipolar SPWM scheme is implemented using microprocessor-STM32F407G. The technique is intensively simulated and the evaluated through experimental results on resistive and resistive-inductive loads by comparing uncompensated and compensated states. Simulation and experimental results are presented to demonstrate and confirm the validity of the proposed dead-time compensation method.
32
Min, Shin-Yi, Kasidit Toprasertpong, Mitsuru TAKENAKA, and Shinichi TAKAGI. "Unipolar polarization switching and high-endurance memory operation of HZO/Si anti-ferroelectric FETs." Japanese Journal of Applied Physics, February 3, 2025. https://doi.org/10.35848/1347-4065/adb163.
Full textAbstract:
Abstract We experimentally demonstrate the anti-ferroelectric (AFE) behavior of a Hf1-xZrxO2 (HZO)/Si FET and its potential for high-endurance nonvolatile memory operation. The AFE-HZO FET with Zr content of 75 % exhibits a double polarization switching and half-loop switching of its double hysteresis under bipolar and unipolar bias conditions, respectively. The counterclockwise hysteresis in the transfer Id -Vg characteristics is demonstrated under unipolar Vg sweep through half-loop polarization in AFeFET. The steep subthreshold swing values were observed for both forward and backward Vg sweeps of Id -Vg curves for AFeFET under unipolar bias condition. The nonvolatile feature of AFeFET is achieved by introducing the optimized hold voltage of 1.3 V during the retention period. The threshold voltage shift can be realized by utilizing the unipolar program /erase Vg pulses. Also, the high-endurance properties of HZO/Si AFeFET are demonstrated under unipolar Vg stress with observable memory window up to 109 cycles without gate insulator breakdown.
33
Gnanavel, Chinnaraj, and Kumarasamy Vanchinathan. "Review and design of modular multilevel inverter with modified multicarrier PWM techniques for solar PV applications." Circuit World, June 8, 2022. http://dx.doi.org/10.1108/cw-06-2021-0162.
Full textAbstract:
Purpose These implementations not only generate excessive voltage levels to enhance the quality of power but also include a detailed investigating of the various modulation methods and control schemes for multilevel inverter (MLI) topologies. Reduced harmonic modulation technology is used to produce 11-level output voltage with the production of renewable energy applications. The simulation is done in the MATLAB/Simulink for 11-level symmetric MLI and is correlated with the conventional inverter design. Design/methodology/approach This paper is focused on investigating the different types of asymmetric, symmetric and hybrid topologies and control methods used for the modular multilevel inverter (MMI) operation. Classical MLI configurations are affected by performance issues such as poor power quality, uneconomic structure and low efficiency. Findings The variations in both carrier and reference signals and their performance are analyzed for the proposed inverter topologies. The simulation result compares unipolar and bipolar pulse-width modulation (PWM) techniques with total harmonic distortion (THD) results. The solar-fed 11-level MMI is controlled using various modulation strategies, which are connected to marine emergency lighting loads. Various modulation techniques are used to control the solar-fed 11-level MMI, which is connected to marine emergency lighting loads. The entire hardware system is controlled by using SPARTAN 3A field programmable gate array (FPGA) board and the least harmonics are obtained by improving the power quality. Originality/value The simulation result compares unipolar and bipolar PWM techniques with THD results. Various modulation techniques are used to control the solar-fed 11-level MMI, which is connected to marine emergency lighting loads. The entire hardware system is controlled by a SPARTAN 3A field programmable gate array (FPGA) board, and the power quality is improved to achieve the lowest harmonics possible.
34
Ahmed, Hafiz Furqan, Alireza Lahooti Eshkevari, and Iman Abdoli. "An identical bipolar buck‐boost AC‐AC converter based on a coupled‐inductor with safe‐commutation, high gain, and high efficiency." IET Power Electronics, November 11, 2024. http://dx.doi.org/10.1049/pel2.12818.
Full textAbstract:
AbstractThis article proposes a new identical bipolar buck‐boost AC‐AC converter with integrated coupled inductors. It possesses all the critical features of a bipolar buck‐boost topology, providing both in‐phase and anti‐phase output voltages. Compared to its counterparts, a high boost factor is achieved without large duty ratios due to using magnetic coupling. Also, a high efficiency is obtained. A unipolar half‐cycle modulation is employed in which only half of the switches of a phase‐leg are modulated per half‐cycle. Therefore, only two out of eight power switches operate at high frequency at any instant, ensuring high‐efficiency operation. The safe‐commutation operation is achieved by completely turning on the auxiliary switches of the main phase leg for a half‐cycle, ensuring a continuous inductor current path during dead times. This results in voltage‐spike‐free operation. Additionally, this converter benefits from continuous input current and performs well with inductive and non‐linear loads. The proposed topology can mitigate both voltage sags and swells due to bipolar operation when employed as a dynamic voltage restorer (DVR). Its high boost factor helps compensate for deep voltage sags (above 50%). This article presents the detailed theoretical aspects of the proposed topology, followed by experimental verifications on laboratory‐built hardware.
35
Li, Dongyan, Zexin Li, Yan Sun, et al. "In‐Sublattice Carrier Transition Enabled Polarimetric Photodetectors with Reconfigurable Polarity Transition." Advanced Materials, July 16, 2024. http://dx.doi.org/10.1002/adma.202407010.
Full textAbstract:
AbstractMiniaturized polarimetric photodetectors based on anisotropic two‐dimensional materials attract potential applications in ultra‐compact polarimeters. However, these photodetectors are hindered by the small polarization ratio values and complicated artificial structures. Here, a novel polarization photodetector based on in‐sublattice carrier transition in the CdSb2Se3Br2/WSe2 heterostructure, with a giant and reconfigurable PR value, is demonstrated. The unique periodic sublattice structure of CdSb2Se3Br2 features an in‐sublattice carrier transition preferred along Sb2Se3 chains. Leveraging on the in‐sublattice carrier transition in the CdSb2Se3Br2/WSe2 heterostructure, gate voltage has an anisotropic modulation effect on the band alignment of heterostructure along sublattice. Consequently, the heterostructure exhibits a polarization‐tunable photo‐induced threshold voltage shift, which provides reconfigurable PR values from positive (unipolar regime) to negative (bipolar regime), covering all possible numbers (1→+∞/−∞→−1). Using this anisotropic photovoltaic effect, gate‐tunable polarimetric imaging is successfully implemented. This work provides a new platform for developing next‐generation highly polarimetric optoelectronics.
36
Dai, Yunzhong, and Huaiyu Zhang. "A transformerless Z‐source photovoltaic grid‐connected inverter with coupled inductor coil." Micro & Nano Letters 19, no. 2 (2024). http://dx.doi.org/10.1049/mna2.12193.
Full textAbstract:
AbstractThe quasi‐Z‐source H‐bridge grid‐connected inverter (QHGCI) is well known for its advantages of the void of the shoot‐through problem and the high DC‐voltage utilization. But the existence of the common‐mode leakage current in the power frequency cycle, lower power density, and higher thermal stress make it hard applicable to the grid‐penetrating application. Thus with the purpose to conquer the problem relating to the QHGCI, an innovative transformerless Z‐source photovoltaic grid‐connected inverter with a coupled inductor coil (TZPGCI‐CIC) is proposed. The circuitry topology and an unipolar sine pulse width modulation strategy are first introduced in short. Thereafter, the common‐mode voltage in the whole working process is derived and evaluated through the detailed operating mode analysis, in which a constant value of it has been theoretically revealed. Lastly, a prototype platform of TZPGCI‐CIC is set up and its good performance on leakage current suppression, and lower thermal stress are validated with the experimental results.
37
Dmitrzak-Weglarz, Monika, Aleksandra Szczepankiewicz, Janusz Rybakowski, et al. "Expression Biomarkers of Pharmacological Treatment Outcomes in Women with Unipolar and Bipolar Depression." Pharmacopsychiatry, September 1, 2021. http://dx.doi.org/10.1055/a-1546-9483.
Full textAbstract:
Abstract Introduction This study aimed to find the expression biomarkers of pharmacological treatment response in a naturalistic hospital setting. Through gene expression profiling, we were able to find differentially-expressed genes (DEGs) in unipolar (UD) and bipolar (BD) depressed women. Methods We performed gene expression profiling in hospitalized women with unipolar (n=24) and bipolar depression (n=32) who achieved clinical improvement after pharmacological treatment (without any restriction). To identify DEGs in peripheral blood mononuclear cells (PBMCs), we used the SurePrint G3 Microarray and GeneSpring software. Results After pharmacological treatment, UD and BD varied in the number of regulated genes and ontological pathways. Also, the pathways of neurogenesis and synaptic transmission were significantly up-regulated. Our research focused on DEGs with a minimum fold change (FC) of more than 2. For both types of depression, 2 up-regulated genes, OPRM1 and CELF4 (p=0.013), were significantly associated with treatment response (defined as a 50% reduction on the Hamilton Depression Rating Scale [HDRS]). We also uncovered the SHANK3 (p=0.001) gene that is unique for UD and found that the RASGRF1 (p=0.010) gene may be a potential specific biomarker of treatment response for BD. Conclusion Based on transcriptomic profiling, we identified potential expression biomarkers of treatment outcomes for UD and BD. We also proved that the Ras-GEF pathway associated with long-term memory, female stress response, and treatment response modulation in animal studies impacts treatment efficacy in patients with BD. Further studies focused on the outlined genes may help provide predictive markers of treatment outcomes in UD and BD.
38
Mahata, Chandreswar, Hyojin So, Seyeong Yang, Muhammad Ismail, Sungjun Kim, and Seongjae Cho. "Uniform multilevel switching and synaptic properties in RF-sputtered InGaZnO-based memristor treated with oxygen plasma." Journal of Chemical Physics 159, no. 18 (2023). http://dx.doi.org/10.1063/5.0179314.
Full textAbstract:
Bipolar gradual resistive switching was investigated in ITO/InGaZnO/ITO resistive switching devices. Controlled intrinsic oxygen vacancy formation inside the switching layer enabled the establishment of a stable multilevel memory state, allowing for RESET voltage control and non-degradable data endurance. The ITO/InGaZnO interface governs the migration of oxygen ions and redox reactions within the switching layer. Voltage–stress-induced electron trapping and oxygen vacancy formation were observed before conductive filament electroforming. This device mimicked biological synapses, demonstrating short- and long-term potentiation and depression through electrical pulse sequences. Modulation of post-synaptic currents and pulse frequency-dependent short-term potentiation were successfully emulated in the InGaZnO-based artificial synapse. The ITO/InGaZnO/ITO memristor exhibited spike–amplitude-dependent plasticity, spike–rate-dependent plasticity, and potentiation–depression synaptic learning with low energy consumption, making it a promising candidate for large-scale integration.
39
Sanz-Ruiz, Ricardo, Enrique Gutierrez Ibañes, Esther Perez David, et al. "Abstract 18968: Correlation Between Myocardial Perfusion and Contractility by SPECT and MRI, and Electromechanical Mapping Parameters in Patients with Advanced Coronary Artery Disease. A PRECISE Substudy." Circulation 126, suppl_21 (2012). http://dx.doi.org/10.1161/circ.126.suppl_21.a18968.
Full textAbstract:
Introduction: electromechanical mapping (EMM) of the left ventricle (LV) is a new technique that provides us with voltage (unipolar and bipolar voltage) and contractility (lineal local shortening) information of the LV. The objective of this study was to assess the correlation between EMM parameters and myocardial perfusion and contractility by SPECT/MRI, in patients with advanced chronic coronary artery disease (CAD). Methods: the PRECISE clinical trial of freshly isolated adipose-derived stem cells for angiogenesis included pts with chronic stable CAD, reversible perfusion defects detectable by SPECT and not amenable for revascularization. Wall motion score index was assessed with MRI imaging in all patients (normal=1; hypokinetic=2; akinetic=3). Perfusion was studied with SPECT Tc-99m sestamibi (normal=grade 0; most impaired=grade 4) and EMM was performed with the NOGA XP system, all using the same 17-segment polar map of the LV. All studies were performed and analyzed by independent observers blinded to the results of the other techniques. Results: 27 consecutive pts were included (62±8 years and 77% male). A total of 865 SPECT and MRI segments were correlated with the corresponding EMM data. Segments with better perfusion at rest and stress (fig.1), and segments with better WMSI by MRI (fig.2) had better voltage and local shortening parameters. Conclusions: EMM is a useful technique for assessing myocardial health status in terms of perfusion and contractility in chronic CAD pts, and can be used for a precise delivery of stem cell therapy.
40
Võ, Quốc Thái, and Nhờ Văn NGUYỄN. "A novel PWM technique to eliminate common-mode voltage for single-phase three-level T-NPC inverter." Science & Technology Development Journal - Engineering and Technology, 2021. http://dx.doi.org/10.32508/stdjet.v4i4.925.
Full textAbstract:
This paper presents a new pulse width modulation (PWM) technique in order to eliminate common mode voltage for a single-phase full H-bridge T-NPC inverter. Three-level NPC inverters are commonly used in grid connected applications or as UPS backup power for industry. In addition to abilities such as to withstand high voltage, and reach output voltage and current with low harmonic distortion, three-level NPC inverter is advantageous for mitigating common mode voltage and leakage current. The new proposed PWM technique is based on the switching state table of the three-level H-bridge T-NPC inverter that containing many switching states with zero common mode voltage. Furthermore, implementation of PWM control for single-phase three-level T-NPC inverter configuration can decrease voltage stress on the output and reduce output voltage distortion compared with bipolar PWM control technique for two-level H-bridge inverter. In this paper, the sine wave carrier PWM technique is analyzed, designed and modelled based on the switching table. The analytical analysis will be evaluated using MATLAB/SIMULINK. Simulation results of the proposed PWM technique for three-level T-NPC inverter are compared with conventional techniques without common mode voltage elimination; the quality of the three-level T-NPC inverter is also compared to that of traditional two-level inverter. The power loss content is evaluated using PLECS software. The obtained results confirm the advantages of the eliminated common mode voltage PWM technique in the three-level T-NPC inverter configuration.
41
Liu, Yi, Jinlong Yao, Ying Dan Liu, and Yongri Liang. "Bending, electroadhesion and sensing performances of single compliant electrode dielectric elastomer actuator based on SEBS gel." Smart Materials and Structures, May 3, 2024. http://dx.doi.org/10.1088/1361-665x/ad4757.
Full textAbstract:
Abstract Dielectric elastomer actuators (DEAs) have great potential for application in soft robotics due to their ability to undergo substantial deformations, rapid response times, and high energy density when subjected to external electrical stimuli. However, the application of DEAs in the field of soft grippers is limited by their restricted direct electro-bending capability, output force, self-sensing capacity, and pre-stretching requirement. In this study, we fabricated a single compliant electrode dielectric elastomer actuator (SCE-DEA) which was made by sandwiching a compliant electrode between two layers of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS)/white mineral oil (WO) dielectric elastomer films. The SCE-SEBS/WO was demonstrated to have the capacities of bending, sensing, and electroadhesion. The SCE-SEBS/WO can be used in various soft actuator modes, such as the unipolar electroadhesion actuator, soft gripper, and soft vibrator. The grabbing mechanism of SCE-SEBS/WO-based soft grippers with opposite bipolar configuration is caused by electric field induced bending of SEC-SEBS/WO and subsequent electrostatic attraction between both SEC-SEBS/WO. The SEC-SEBS/WO based soft grippers have rapid response detachment, and ability to grasp various types of objects. Three-layer stacked SCE-SEBS/WO-60 (with 60 wt% of WO) exhibited 531 mN/cm2 of electroadhesion stress on the paper at 3.0 kV applied voltage, and the soft gripper made by four SCE-SEBS/WO-60 can successfully grab wood blocks weighing 162.4 g at 5 kV applied voltage. The sensing capacity of SCE-SEBS/WO based soft gripper was based on the bending strain dependent resistance changes of the compliant electrode. Our results provide new insights into the fabrication of DEA based soft grippers.