Switching Devices Research Articles

A Modified SVPWM Strategy for Reducing PWM Voltage Noise and Balancing Neutral Point Potential

PWM (pulse width modulation) is the most widely applied current conversion technology, but the high-frequency harmonics it causes have a significant negative impact on inverter system performance. This paper focuses on the three-phase T-type three-level inverter as the research object and addresses existing PWM voltage noise and midpoint potential imbalance issues by proposing an improved random SVPWM strategy, named Neutral Point Potential Balance Random Space Vector PWM (NPB–RSVPWM). The NPB–RSVPWM strategy includes three main steps: (1) introducing a midpoint potential balancing control loop to adjust the synthesis timing of the effective vectors to generate pulse signals, optimizing midpoint potential balance; (2) employing a randomly varying carrier frequency in place of the carrier used in the SVPWM strategy to generate the driving signals for switching devices; and (3) controlling the inverter through the driving pulse signals. This strategy optimizes the synthesis sequence of traditional SVPWM strategy vectors and incorporates random frequency modulation techniques. The mathematical model analyzes PWM harmonic expressions corresponding to fixed switching frequencies, and a random frequency carrier is chosen to suppress these PWM harmonics. The effective vector’s equivalent circuit is analyzed, proposing a technique for optimized vector synthesis timing. The simulation and experimental results verify that the NPB–RSVPWM technique can disperse PWM harmonic energy, reduce voltage noise, and optimize midpoint potential balance. Under the NPB–RSVPWM strategy, the line voltage spectrum becomes uniform, the maximum harmonic content is greatly reduced, and the fluctuation in the DC side midpoint potential is significantly improved. Compared with the traditional SVPWM strategy and random PWM strategy, the NPB–RSVPWM strategy has a lower voltage noise, smaller total harmonic distortion, and a more stable midpoint potential. The effectiveness and feasibility of the NPB–RSVPWM strategy are verified by simulation and experimental results.

Harmonic Interaction Analysis of Inverters Based on Harmonic State-Space Model Considering Dead-Zone Effect

In the context of increasing device switching frequencies year by year, non-ideal factors such as dead-zone effects in inverters not only cause output waveform distortion, but also generate harmonics that make the interaction between inverters and power grids more complex. In order to accurately describe and analyze this phenomenon and establish a more practical grid-connected inverter model, this paper proposes and establishes a three-phase LCL grid-connected inverter harmonic state space model that considers dead-zone effects. By incorporating dead-zone effects into the modeling process, the system transfer function matrix is derived to quantify the harmonic interaction coefficient between the inverter and the power grid, and the influence mechanism of dead-zone effects on the harmonic interaction process at high switching frequencies is analyzed in depth. The necessity of considering dead-zone effects is illustrated through simulation, and the effectiveness and accuracy of the inverter HSS model considering the effects of dead-zone effects are verified through experiments.

Exchange-coupling enhanced: Tailoring structural and magnetic properties of Dy iron garnet ferrite nanoparticles via La substitution for switching devices

Exchange-coupling enhanced: Tailoring structural and magnetic properties of Dy iron garnet ferrite nanoparticles via La substitution for switching devices

Phase-change behavior of RuSbTe thin film for photonic applications with amplitude-only modulation.

Ge2Sb2Te5 (GST), the most mature phase-change materials (PCM), functions as a recoding layer in nonvolatile memory and optical discs by contrasting the physical properties upon phase transition between amorphous and crystalline phases. However, GST faces challenges such as a large extinction coefficient (k) and low thermal stability of the amorphous phase. In this study, we introduce RuSbTe as a new PCM to address the GST concerns. Notably, the crystallization temperature of the amorphous RuSbTe is approximately 350 °C, significantly higher than GST. A one-order-of-magnitude increase in the resistivity contrast was observed upon phase transition. The crystalline (0.35-0.50eV) and amorphous (0.26-0.37eV) phases exhibit relatively small band gap values, resulting in substantial k. Although RuSbTe demonstrates a k difference of approximately 1 upon crystallization at the telecommunications C-band, the refractive index (n) difference is negligible. Unlike GST, which induces both phase retardation and amplitude modulation in its optical switch device, RuSbTe exhibits amplitude-only modulation. This study suggests that RuSbTe has the potential to enable new photonic computing devices that can independently control the phase and amplitude. Combining RuSbTe with phase-only modulators could open avenues for advanced applications.

Understanding asymmetric switching times in accumulation mode organic electrochemical transistors.

Understanding the factors underpinning device switching times is crucial for the implementation of organic electrochemical transistors in neuromorphic computing, bioelectronics and real-time sensing applications. Existing models of device operation cannot explain the experimental observations that turn-off times are generally much faster than turn-on times in accumulation mode organic electrochemical transistors. Here, using operando optical microscopy, we image the local doping level of the transistor channel and show that turn-on occurs in two stages-propagation of a doping front, followed by uniform doping-while turn-off occurs in one stage. We attribute the faster turn-off to a combination of engineering as well as physical and chemical factors including channel geometry, differences in doping and dedoping kinetics and the phenomena of carrier-density-dependent mobility. We show that ion transport limits the operation speed in our devices. Our study provides insights into the kinetics of organic electrochemical transistors and guidelines for engineering faster organic electrochemical transistors.

Analyzing and mitigating parasitic capacitances in planar transformers for high-frequency operation

Planar magnetic components are compact and less susceptible to skin effect due to their thin copper layers. However, the increase in parasitic capacitance has been a challenge in high-frequency operation of planar transformers (PTs). Parasitic capacitances resonate with inductance and may damage switch devices. Thicker printed circuit board (PCB) and reconfigured windings are suggested in this paper to mitigate the parasitic capacitances. A detailed analysis of the parasitic capacitances is performed with a prototype PT. The resonant frequency increased from 1.27 to 1.63 MHz with a 0.4 mm thicker PCB. The reconfigured PT was 1.38 MHz, 0.3 MHz higher than the original PT.

Write error rate analysis of field-free spin-orbit torque switching in conically magnetized free layer nanomagnet

Enhancing the performance of magnetic random access memories (MRAMs) is crucial, considering speed, energy efficiency, and endurance. Spin-orbit torque-based MRAMs offer ultrafast operation and enhanced reliability. Still, the energy efficiency and external magnetic field requirement for deterministic switching of nanomagnets with perpendicular magnetic anisotropy (PMA) are a significant hurdle. To address these issues, one of the proposed solutions employs a conically magnetized free layer magnetic tunnel junction device featuring second-order PMA. This approach can minimize the required switching current density by leveraging the interplay between first- and second-order PMA energies. Additionally, coupling with exchange bias from the antiferromagnet can eliminate the need for an external field entirely. Our analysis investigates the impact of current density (magnitude and rise/fall time), first- and second-order PMA fields, exchange bias, and field-like torque on the device's switching performance. By optimizing the perpendicular magnetic anisotropies, we report improvement in the write error rate from 10−4 to 10−7. Our findings hold promise for magnetic memory applications.

Domain reorientation due to smectic layer instability in high tilt angle-based surface stabilized ferroelectric liquid crystal cell

High tilt angle (45°) ferroelectric liquid crystal (FLC) in surface stabilized geometry, having no chiral smectic A (SmA∗) phase, has been studied for the reorientation of the smectic layers near the transition temperature (Tc). The electro-optical studies have shown the stripe domain formation in which the liquid crystal molecules are aligned along the rubbing direction, but the smectic layers are tilted away from the rubbing direction at room temperature. In such high tilt angle FLCs, the molecular alignment and smectic layer formation start from bottom and top rubbed grooves at Tc. The domain formation of the FLC takes place in the middle of the top and bottom surfaces due to the frustration of the dipolar interaction. The smectic layer switching is observed by optical microscopy and confirmed by the dielectric spectroscopy method near Tc of SmC∗ and chiral nematic phases. Domain switching has shown a larger switching angle than the molecular tilt angle within the smectic layer. These studies are expected to be significant for understanding the smectic layer structure and the domain switching process, which may pave the way for large optical switching devices.

Achievements in the Photomagnetic Effect of Cobalt‐Iron Prussian Blue Analogues

AbstractHarnessing light for magnetization control presents a promising approach with compelling merits such as non‐contact operation, ultrafast response, reversibility, high spatial resolution, tunability, and energy efficiency. Photoinduced metal‐to‐metal charge transfer (MMCT) is one key mechanism in achieving photo‐controlled magnetic properties, making relevant materials prime candidates for versatile switchable devices. Cobalt iron Prussian blue analogues (CoFePBA) are trailblazers in showcasing photomagnetic properties via MMCT and the numerous related studies on CoFePBA have significantly enhanced the understanding of photoinduced MMCT processes. Thus, this review embarks on a thorough examination of three decades of research on the photomagnetic of CoFePBA to deep into the art of the photocontrol of spin. In addition to an introduction to the structure and preparation of CoFePBA, the focus is on elucidating the underlying mechanisms and introducing strategies for its manipulation and control. Finally, the challenges and prospects at this moment are summarized and discussed.

Compact non-volatile multilevel Sb2Se3 electro-optical switching in the mid-infrared group-IV-photonics platform

This theoretical modeling and simulation paper presents designs and projected performances of two non-volatile, broadband, on-chip 2 × 2 electro-optical switches based upon the germanium-on-insulator (GeOI) photonic-electronic platform operating at the 2.5 µm mid-infrared wavelength. These compact devices facilitate large-scale integration on a “monolithic wafer” where all components are made of group-IV semiconductors. The switches are the two-waveguide directional coupler (DC) and the Mach-Zehnder interferometer (MZI). A thin-film graphene Joule-effect micro-heater is assumed on the planarized GeOI device to change the phase (reversably) of DC-slot-embedded Sb2Se3 phase-change material (PCM) from crystalline to amorphous. The MZI has this PCM within its slotted-arm waveguides. Simulations show high-performance bistable or multi-stable cross-bar switching in both devices. The 2 × 2 DC has an active coupling length of 17 µm, 130 nm gap, and a footprint of 5 µm x 31 µm. The device bandwidth is 30 nm over a wavelength range where cross and bar insertion losses IL are less than 0.3 dB, and where optical crosstalk is less than −15 dB. Results for the 2 × 2 MZI show crossbar switching attained with a 7.8 µm-length Sb2Se3 slot and a 5 µm x 51 µm switch footprint. Stable, multi-level switching in both devices is attained via partial amorphization. Thermal modeling shows that careful control of the voltage-pulse amplitude V applied to graphene (rectangular pulse duration of 500 ns) can give 32 levels, for example, using V in the range from 6.18 to 7.75 Volts. Multi-level switching is shown also in PCM-based ring resonators.

A comprehensive investigation of Bi2O3 on the physical, structural, optical, and electrical properties of K2O.ZnO.V2O5.B2O3 glasses

The multi-component glass system has a composition of 10K2O–10ZnO–55 B2O3–(25–x)V2O5–xBi2O3 (x = 4, 5, 7.5, 9, 10 mol%) are synthesized by the melt-quenching method. Using X-ray diffraction examination, the amorphous phase in the material was confirmed. The physical characteristics of the produced compositions are examined using density (D) and molar volume (Vm). Calculations of physical properties showed that adding Bi2O3 from 4 to 10 mol% increased the glass density from 2.7878 to 3.3617 g cm−3 and decreased the molar volume from 40.4196 to 38.5895 cm3/mol. Studies of glass samples using the FTIR show bands of absorption for oxides in different structural groups. Octahedral [BiO6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{BiO}}}_{6}$$\\end{document}], [BO4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{BO}}}_{4}$$\\end{document}], and tetrahedral [BO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{BO}}}_{3}$$\\end{document}] structural units are observed in the present glass matrices. The cutoff wavelength (λC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{C}$$\\end{document}), and optical band gap energy were determined using UV absorption spectra. The increase in non-bridging oxygens can be linked to the decrease in optical band gap energy (Eopt\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${E}_{opt}$$\\end{document}) (direct and indirect) and the increase in cutoff wavelength with an increase in Bi2O3 content. This is attributed to the existence of bismuth ions and the creation of non-bridging oxygens. Besides that, the values of optical parameters, viz., optical electronegativity, refractive index, and molar refractivity, are calculated. The metallization criterion values are less than 1 and the glass samples exhibit an increased tendency towards metallization. Both the conductivity and the dielectric constant increase with the rise in Bi2O3 content, however, the dielectric loss and the impedance reduce. The behavior and values of conductivity for the studied glasses reveal the semiconducting properties of all glass samples. These results suggest that the produced glass samples may be employed as amorphous semiconductors in electronics and memory switching devices.

Design and Construction of Voice Controlled Home Automation using Arduino

System automation has been widely researched in the twenty-first century due to its essential role in daily life. The fundamental advantage of an automated system is its ability to reduce human stress and minimize errors. Over the past few years, there has been a swift shift from traditional switches to switches equipped with remote controls. Currently, the presence of conventional wall switches distributed around the house poses challenges in terms of use, especially for individuals who are elderly or have physical disabilities. Due to technological advancements, mobile smartphones are now affordable for all individuals. Android devices are becoming equipped with applications that aid in multiple ways. Another new technology is the Google speech recognition APIs, which enable voice-based system command and control. This study demonstrates the implementation of voice-controlled home automation using the Arduino Uno microcontroller. Users of this system will be able to exercise full authority over every domestic device through spoken commands. The control circuit consists of an Arduino Uno microcontroller that receives and interprets voice commands from an Android smartphone equipped with the corresponding application. While the Bluetooth module shares signal data after establishing a wireless link between the microcontroller and the smartphone, the relay regulates device switching.

Output quality improvement for single‐phase inverter in V2G system

AbstractIn vehicle‐to‐grid (V2G) applications, a voltage source inverter (VSI) directly connects to a residential load or grid for DC/AC conversion and power flow control. In VSI, dead‐time is employed to prevent the breakdown of switching devices, however, the introduction of dead‐time leads to distortions of output voltage and current in both stand‐alone and grid‐tie modes. For the case of a power factor of 1, by analyzing the dead‐time effect of digital‐controlled double‐frequency sinusoidal pulse width modulation, a compensation amount is proposed to introduce in the modulation signals, the value of which is half of the delay register that generates a dead‐time of td. Moreover, considering the phase delay caused by hardware and software filtering in sampling, the grid‐tie mode control strategy based on dead‐time compensation is further proposed, which introduces the grid voltage as a feedforward signal. A 3.5 kW V2G experimental prototype is built and tested to verify the feasibility of the proposed strategies. The simulation and experimental results show that the proposed methods are effective for both modes, which improve the output distortion for different dead‐time without additional hardware circuits.

Transient N-GQDs/PVA nanocomposite thin film for memristor application

In recent years quantum dot (QDs) based resistive switching devices(memristors) have gained a lot of attention. Here we report the resistive switching behavior of nitrogen-doped graphene quantum dots/Polyvinyl alcohol (N-GQDs/PVA) degradable nanocomposite thin film with different weight percentages (wt.%) of N-GQDs. The memristor device was fabricated by a simple spin coating technique. It was found that 1 wt% N-GQDs/PVA device shows a prominent resistive switching phenomenon with good cyclic stability, high on/off ratio of ~102 and retention time of ∼104 s. From a detailed experimental study of band structure, we conclude that memristive behavior originates from the space charge controlled conduction (SCLC) mechanism. Further transient property of built memristive device was studied. Within three minutes of being submerged in distilled water, the fabricated memory device was destroyed. This phenomenon facilitates the usage of fabricated memristor devices to develop memory devices for military and security purposes.

Four-channel holographic metasurface based on frequency-angle multiplexing

Due to the powerful ability of metasurfaces to manipulate light fields, various optical parameters have been widely explored and studied through precise design of metasurface units. However, the angle of incidence, which is one of the important optical parameters, has not been fully investigated for multiplexing due to the lack of coding degrees of freedom. Here, the scheme of four-channel holographic metasurface based on frequency-angle multiplexing is proposed to achieve independent display of multiple images at different frequencies and angles. The metasurface units used are Metal-Insulator-Metal structures that can effectively manipulate the electromagnetic wave’s amplitude in the reflection space to accommodate various operating frequencies and angles of incidence. The effectiveness of the proposed four-channel holographic scheme is verified by encoding four independent amplitude image information into a metasurface array. The four-channel scheme proposed in this paper successfully breaks the limitation of angular correlation and improves the density and capacity of information storage. This not only provides a higher degree of freedom and flexibility for multi-channel metasurface holographic imaging, but also holds significant importance for advancing optical information processing and display technologies. It is believed that the metasurface based on frequency-angle multiplexing can easily find more promising applications, including electromagnetic wavefront control, encryption/ concealment of optical information, and multifunctional switchable devices.

Vacancy-Engineered Nickel Ferrite Forming-Free Low-Voltage Resistive Switches for Neuromorphic Circuits.

Innovations in resistive switching devices constitute a core objective for the development of ultralow-power computing devices. Forming-free resistive switching is a type of resistive switching that eliminates the need for an initial high voltage for the formation of conductive filaments and offers promising opportunities to overcome the limitations of traditional resistive switching devices. Here, we demonstrate mixed charge state oxygen vacancy-engineered electroforming-free resistive switching in NiFe2O4 (NFO) thin films, fabricated as asymmetric Ti/NFO/Pt heterostructures, for the first time. Using pulsed laser deposition in a controlled oxygen atmosphere, we tune the oxygen vacancies together with the cationic valence state in the nickel ferrite phase, with the latter directly affecting the charge state of the oxygen vacancies. The structural integrity and chemical composition of the films are confirmed by X-ray diffraction and hard X-ray photoelectron spectroscopy, respectively. Electrical transport studies reveal that resistive switching characteristics in the films can be significantly altered by tuning the amount and charge state of the oxygen vacancy concentration during the deposition of the films. The resistive switching mechanism is seen to depend upon the migration of both singly and doubly charged oxygen vacancies formed as a result of changes in the nickel valence state and the consequent formation/rupture of conducting filaments in the switching layer. This is supported by the existence of an optimum oxygen vacancy concentration for efficient low-voltage resistive switching, below or above which the switching process is inhibited. Along with the filamentary switching mechanism, the Ti top electrode also enhances the resistive switching performance due to interfacial effects. Time-resolved measurements on the devices display both long- and short-term potentiation in the optimized vacancy-engineered NFO resistive switches, ideal for solid-state synapses achieved in a single system. Our work on correlated oxide forming-free resistive switches holds significant potential for CMOS-compatible low-power, nonvolatile resistive memory and neuromorphic circuits.

Evaluation of various phase-transition materials for steep switching super-low power application in the latest technology node

Recently, a phase-transition field effect transistor (phase-FET) integrated with a phase-transition material (PTM) is attracting attention as a steep switching device, and attempts to solve the power consumption limitation of conventional CMOS using various PTMs are continuing. In order to utilize the phase-FET, it is essential to design an appropriate device and circuit characteristics by carefully considering the close correlation between the baseline-FET and the PTM and the hysteresis characteristics caused by the phase-transition. In this work, by integrating various PTMs according to the baseline FETs in various technology nodes, the logic and SRAM characteristics implemented the phase-FET were investigated, and the appropriate PTM and the electrical characteristic target required for the PTM were presented through systematic analysis. As a result, it was confirmed that single crystalline vanadium di-oxide (SC VO2) has characteristics suitable for constructing phase-FETs compared to other candidate PTMs in 32 nm planar FET, 7 nm Fin-FET, and 3 nm gate-all-around FET technology nodes. As a result of benchmarking with conventional-FET at each technology node, in the case of logic, the speed is 26.15% (32 nm), 20.26% (7 nm), and 20.05% (3 nm), and in the case of memory, standby power, read stability and write time are improved.

Automatic test-bench for SiC power devices using LabVIEW

Abstract This paper is devoted to the improvement existing models of electronics devices, which are used in powers electronics as switching devices, and investigate a LabVIEW-based automatic test-bench for Silicon carbide (SiC) power devices. In recent years, power electronic devices are required to be capable handle with higher voltage, leads to development of new generation of power electronic devices, such as SiC devices. However, using a simulation platform, such as Spice, to diminish the complexity of power electronic design with these new devices is hindered by the lack of precise models. The proposed test-bench enables not only measuring static characteristics of SiC power devices, but also extracting key parameters required by simulations. These extracted parameters are then employed in the existing device model, and the simulation results which are based on the model with original parameters and models with extracted parameters are compared with measured results. The comparison clearly demonstrates that parameters obtained from the proposed test-bench significantly enhance the Spice model.

A Comparative Study of 9-Level Inverter and 15-Level Multi Inverter for a Grid Connected System

Abstract: Recently, the emergence of single phase multilevel inverter has been increased due to its advantages over traditional one. Multilevel Inverters [MLI] are the ones which can give out a stepwise output waveform with the use of power electronic switches, power diodes and some DC voltage source which might be a series/parallel connected PV cells, a renewable source or a battery. Multilevel inverters not only produce low harmonic distortion but also decrease the dv/dt stresses on the equipment Multilevel inverters is a good option as the output voltage of a Multilevel inverter is a stepped waveform which approaches a sinusoid providing lesser harmonic distortion. As the number of levels are increased the harmonic distortion reduces but at the same time the number of switching devices and the DC voltage sources required increases, thus increasing the complexity of the system design and control. Multilevel inverter proposed in this paper uses only 7 switches to provide 9 levels and 15 levels of output voltage. A symmetrical Cascaded H bridge Multi level inverter (SCHBMLI) and Asymmetrical Cascaded H bridge Multilevel Inverter (ASCHBMLI) using PD-PWM technique have been analysed in this paper for grid connection. The Asymmetric Cascade H Bridge [ASCHMLI] implemented in real time system using PIC16F877A microcontroller with RL load. This type of proposed system is used for high power applications in photovoltaic and it’s reduce overall cost as well as size of the system.

Multi-optimized reconfiguration of hybrid photovoltaic-thermoelectric generation (PV-TEG) system for performance enhancement

This study designs a hybrid photovoltaic-thermoelectric generation (PV-TEG) system, aimed at achieving an efficient photo-thermal-electrical energy conversion. However, dynamically varying real-world environmental conditions frequently lead to partial shading conditions (PSCs) and non-uniform thermal distribution (NTD), which adversely affect the system’s output characteristics, resulting in power loss and compromised operation reliability. To alleviate the mismatch effects caused by PSCs and enhance the output power of hybrid PV-TEG systems while maintaining the electrical connections intact, array reconfiguration is a desirable solution. However, existing research on PV-TEG system reconfiguration only focuses on maximizing power output, neglecting the importance of service life and control complexity of switching devices. To bridge this gap, this study proposes a multi-optimized PV-TEG reconfiguration strategy based on the devised chaos-driven dynamical interactive whale optimization algorithm (CDI-WOA), aiming at simultaneously improving the power output while minimizing unnecessary switching actions to prolong the service life of switching devices. Case studies are carried out using two commonly utilized scales of array configuration in engineering, i.e., 6x6 and 6x10 arrays under ten different PSC patterns for systematic validation. Five evaluation indicators are employed for a more comprehensive performance evaluation than prior work, the results demonstrate that CDI-WOA based reconfiguration can increase the maximum power output by 28.24% and 32.02% for 6x6 and 6x10 arrays compared with that without reconfiguration, respectively.