Vertical Switch Research Articles

EMB-YOLO: A Lightweight Object Detection Algorithm for Isolation Switch State Detection

In power inspection, it is crucial to accurately and regularly monitor the status of isolation switches to ensure the stable operation of power systems. However, current methods for detecting the open and closed states of isolation switches based on image recognition still suffer from low accuracy and high edge deployment costs. In this paper, we propose a lightweight object detection model, EMB-YOLO, to address this challenge. Firstly, we propose an efficient mobile inverted bottleneck convolution (EMBC) module for the backbone network. This module is designed with a lightweight structure, aimed at reducing the computational complexity and parameter count, thereby optimizing the model’s computational efficiency. Furthermore, an ELA attention mechanism is used in the EMBC module to enhance the extraction of horizontal and vertical isolation switch features in complex environments. Finally, we proposed an efficient-RepGDFPN fusion network. This network integrates feature maps from different levels to detect isolation switches at multiple scales in monitoring scenarios. An isolation switch dataset was self-built to evaluate the performance of the proposed EMB-YOLO. The experimental results demonstrated that the proposed method achieved superior detection performance on our self-built dataset, with a mean average precision (mAP) of 87.2%, while maintaining a computational cost of only 6.5×109 FLOPs and a parameter size of just 2.8×106 bytes.

Vertical Switching Algorithm for Unmanned Aerial Vehicle in Power Grid Heterogeneous Communication Networks

The rapid development of wireless network technology has led to the coexistence of various heterogeneous wireless networks (HWNs). To ensure that users enjoy normal and diversified services, research on vertical switching technology has become an inevitable trend. However, most current vertical switching algorithms only consider static situations or single services, which are not suitable for power grid scenarios. This paper studies the vertical switching problem of wireless heterogeneous networks for unmanned aerial vehicles (UAVs) performing inspection tasks in power grid scenarios. In this model, a UAV for power grid inspection needs to plan its flight trajectory, avoid obstacles, and find the optimal trajectory to reach each inspection point. Throughout the UAV inspection process, we must ensure the quality of communication services for the UAV. The UAV dynamically selects different networks for access at different locations, presenting a dynamic network selection and vertical switching problem. This paper proposes a method that combines trajectory planning and network selection, which first utilizes the A-star algorithm to obtain suitable trajectories, and then evaluates and judges networks based on the Fuzzy Analytic Hierarchy Process (FAHP) to determine the most appropriate network. It is worth noting that this paper considers three service requirements and seven network attributes under three types of heterogeneous wireless networks. Numerical results show that this method can better meet the requirements of UAV inspection tasks and reduce the number of switches, thus addressing the issue of terminal vertical switches in power grid scenarios.

Effect of annealing residual stress on mobility of TSV vertical switch

Effect of annealing residual stress on mobility of TSV vertical switch

A Global Assessment of Eddy‐Induced Salinity Anomalies and Salt Transport by Eddy Movement

AbstractEddy‐induced salt transport is essential in maintaining the oceanic salinity balance and global climate. However, the paucity of in situ measurements poses challenges in obtaining the spatial structure of the eddy salt transport globally. Here, we conduct a global estimation of eddy‐induced salinity anomalies and salt transport by eddy movement using 2 million historical hydrographic profile measurements and satellite‐based eddy observations spanning from 1993 to 2019. The results demonstrate rich geographic and vertical variability in the salinity anomalies induced by eddies across the global ocean. Vertical sign switches of salinity anomalies within eddies are observed in the tropical and subtropical oceans, as well as in the Kuroshio Extension region. Additionally, meridional sign switches of eddy‐induced salinity anomalies are observed in the Antarctic Circumpolar Current region. By integrating eddy occurrence probability, we refine the methodology for estimating eddy‐induced salt transport, and provide global spatial patterns of both meridional and zonal salt transport induced by eddy movement at each 2° × 2° grid. Significant salt transport by meridional eddy movement is observed in the mid‐latitude oceans, with the peak zonal‐depth integrated salt transport reaching 106 kg·s−1 in the mid‐latitudes of the southern hemisphere. Specifically, the Brazil‐Malvinas Confluence region is identified as a highly efficient pathway for meridional salt transport, with a magnitude of −1.28 × 106 kg·s−1, significantly surpassing other regions in the global ocean. These findings may provide important references for the understanding and simulation of global oceanic salinity transport.

Characteristics Comparison of SiC and GaN Extrinsic Vertical Photoconductive Switches

Characteristics Comparison of SiC and GaN Extrinsic Vertical Photoconductive Switches

Vertical PtOx/Pt/ β -Ga2O3 Schottky diodes with high permittivity dielectric field plate for low leakage and high breakdown voltage

We demonstrate Schottky barrier engineering using PtOx/thin Pt Schottky contacts combined with edge termination using a high permittivity dielectric (ZrO2) field-plate for high-voltage vertical β-Ga2O3 diodes. A systematic study of baseline bare Pt/β-Ga2O3, PtOx/thin Pt/β-Ga2O3, and PtOx/β-Ga2O3 Schottky diode characteristics was performed, which revealed that the PtOx/thin Pt/β-Ga2O3 contact can combine the advantages of both PtOx and Pt, allowing better reverse blocking performance than plain metal Pt/β-Ga2O3 Schottky diodes and lower turn-on voltage than plain oxidized metal PtOx/β-Ga2O3 ones. Moreover, the thin Pt interlayer in the PtOx/thin Pt/β-Ga2O3 anode contact configuration, deposited by e-beam deposition, also provides plasma-free interface at the Schottky junction as opposed to the direct sputter deposited PtOx contacts of the PtOx/β-Ga2O3 diodes. We further implemented a high permittivity dielectric (ZrO2) field plate in PtOx/thin Pt/β-Ga2O3 diodes that assisted in edge-field management and enabled a breakdown voltage to ∼2.34 kV. These results indicate that the PtOx/thin Pt/β-Ga2O3 Schottky contact, combined with a high permittivity field-plate, will be promising to enable Schottky barrier engineering for high-performance and efficient vertical β-Ga2O3 power switches.

Breakdown and Photoconductivity Enhancement by Mixed Reflective Al-Doped ZnO/Ag Electrode in Vertical SiC Photoconductive Switch

an axial-triggering vertical SiC photoconductive switch with Al-doped ZnO placed under the Ag electrode is developed to enhance breakdown strength and photoconductivity. Traditional and new devices with the AZO/SiC/Ag and AZO/SiC/AZO/Ag structures, respectively, were prepared. Test results show that the conductivity of the new device is approximately 1.2 times higher than that of the old one, attributable to the diffuse reflection effects of the AZO/Ag mirror. Under high bias voltages of up to 16.5 kV/mm and a 30-ns pulse width laser input, the new device shows significantly enhanced breakdown strength. The new device has a lifetime of >1E4 shots, whereas the old device has a maximum lifetime of approximately 1E2 shots. The new device can continuously output electrical pulses for 10 minutes at a 100 Hz repetition rate, 30-ns pulse width, and 100 A peak current without breakdown.

Effects of horizontal versus vertical switching of disease-modifying treatment after platform drugs on disease activity in patients with relapsing–remitting multiple sclerosis in Austria

ObjectivesTo compare in a nationwide observational cohort the effectiveness, frequency and reasons for treatment interruption of dimethylfumarate (DMF) and teriflunomide (TERI) (horizontal switchers) versus alemtuzumab (AZM), cladribine (CLAD), fingolimod (FTY), natalizumab (NTZ), ocrelizumab (OCR) and ozanimod (OZA) (vertical switchers) in patients with relapsing–remitting multiple sclerosis (pwRRMS) and prior interferon beta (IFN-beta) or glatiramer-acetate (GLAT) treatment.Materials and methodsThe “horizontal switch cohort” included 669 and the “vertical switch cohort” 800 RRMS patients. We used propensity scores for inverse probability weighting in generalized linear (GLM) and Cox proportional hazards models to correct for bias in this non-randomized registry study.ResultsEstimated mean annualized relapse rates (ARR) were 0.39 for horizontal and 0.17 for vertical switchers. The incidence rate ratio (IRR) in the GLM model showed an increased relapse probability of 86% for horizontal versus vertical switchers (IRR = 1.86; 95% CI 1.38–2.50; p < 0.001). Analyzing the time to the first relapse after treatment switch by Cox regression, a hazard ratio of 1.58 (95% CI 1.24–2.02; p < 0.001) indicated an increased risk of 58% for horizontal switchers. The hazard ratios for treatment interruption comparing horizontal versus vertical switchers were 1.78 (95% CI 1.46–2.18; p < 0.001).ConclusionsHorizontal switching after a platform therapy resulted in a higher relapse and interrupt probability and was associated with a trend towards less EDSS improvement comparing to vertical switching in Austrian RRMS patients.

Fault-Tolerant Sequential MPC for Vertical Switch Open-Circuit Fault and ZSCC Suppression for Parallel T-Type Converters

A fault-tolerant control (FTC) is proposed for enhancing the reliability of power electronic systems. The software-based FTC of parallel-connected three-level T-type converters (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cs) for suppressing zero-sequence circulating current (ZSCC) induced by a vertical switch open-circuit fault is investigated. A simplified sequential model predictive control (SSMPC)-based FTC technique is developed. Parallel-3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cs and their prediction models are introduced, followed by an SSMPC for the no-fault condition. The model inaccuracies under vertical switch faults are elaborated. For the faulty 3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> C, two fault-tolerant SSMPC (FT-SSMPC) methods are provided by creating a sequential predictive controller that considers ZSCC suppression and grid current tracking. The control policies for the ZSCC are changed from the standard feedback-free to feedback-based cost function (CF) optimization using the unimproved FT-SSMPC. Furthermore, an improved FT-SSMPC is proposed using a phase-deficient CF, which increases the accuracy of the mathematical relation of the fault condition. After fault diagnosis, the proposed method achieves neutral-point voltage balance and excellent point-of-common-coupling current, effectively suppresses the ZSCC, and increases the control reliability. Finally, experiments demonstrate the effectiveness of the proposed FT-SSMPC under various conditions.

Vertical SiC Photoconductive Switch With Axial Optical Internal Reflection Trap

The SiC vertical photoconductive switch with an axial optical internal reflection trap to improve the ON-state performance is presented. The extrinsic light absorption of vanadium (V)-doped SiC photoconductive switch is low. As such an axial optical reflection trap is used to increase the optical path and total optical absorption. The trap consists of a convex lens, a silver mirror electrode with a hole, and a transparent electrode to create a quasi-total internal reflection structure. Simulation and experimental evaluation reveal that both the device’s light absorption and output current have been improved significantly. Compared with regular axial illumination without the reflective trapping arrangement, the structure fabricated on a V-doped 4H-SiC device demonstrates a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5\times $ </tex-math></inline-formula> improvement in photoelectric conversion responsivity.

Nonlinear Dynamical Analysis of a Stochastic Sirs Epidemic System with Vertical Dissemination and Switch from Infectious to Susceptible Individuals

Nonlinear Dynamical Analysis of a Stochastic Sirs Epidemic System with Vertical Dissemination and Switch from Infectious to Susceptible Individuals

Secure Vertical Handoff in Mobile Wireless Network Based on Secure Location Algorithm

With the continuous development of social economy, mobile wireless network as an important network communication mode is more and more widely used, but its security is worth paying attention to. According to different environment possible switch mobile wireless network security problem, the paper introduced secure localization algorithm, through combing the existing security vertical switching process, the corresponding vertical safety switch security index system was constructed, and the simulation experiment, from safety factor to switch from the mobile wireless network security monitoring the status of the transformation, and use the safety parameter to carry on the quantified computation expression. The simulation results prove that the visualization of the 5G network clearly shows the status of WLAN1. The simulation results show that the secure location algorithm is effective and can support secure vertical handoff in mobile wireless network.

Side-Illuminated Photoconductive Semiconductor Switch Based on High Purity Semi-Insulating 4H-SiC

High purity semi-insulating (HPSI) 4H-silicon carbide (SiC) was used to fabricate lateral and vertical photoconductive semiconductor switches (PCSSs). The lateral PCSSs were illuminated from the frontside (fPCSS) or the backside (bPCSS). The side-illuminated vertical PCSS (vPCSS) was designed to increase the light-matter interaction volume. A 532-nm pulsed laser with adjustable energy was utilized to excite the PCSSs. The turn-on time was found to be highly dependent on the optical illumination energy, and the full-width at half-maximum of the PCSSs output waveforms was related to the peak output voltage. The output electrical pulse from the vPCSS exhibited a shorter turn-on time and a larger pulsewidth than the two types of lateral PCSSs. The vPCSS outperformed the fPCSS and bPCSS in terms of minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{\scriptscriptstyle ON}$ </tex-math></inline-formula> -state resistance and output pulse amplitude under the same optical illumination energy. The vPCSS, which utilizes a large effective contact area to collect photogenerated carriers, also had higher photon absorption efficiency by arranging the optical path at a right angle to the carrier transport. The vPCSS exhibited a minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{\scriptscriptstyle ON}$ </tex-math></inline-formula> -state resistance of 0.34 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> at optical illumination energy of 8 mJ.

TPTPC and BHC integrated grid connected energy storage system for power loss reduction

PurposeThis paper aims to propose a bidirectional hidden converter (BHC)-based three-phase DC–AC conversion for energy storage application. BHC is the new concept to vary an energy storage device voltage into wide range. Hidden converter power loss and power rating are reduced by using zero-sequence injection-based carrier-based pulse-width modulation (CBPWM) strategy.Design/methodology/approachBy using this control strategy, a BHC processes only little amount of power during double-stage conversion, mostly during direct or single-stage conversion of the three-phase three-port converter (TPTPC) only processing the maximum power.FindingsTPTPC consists of two sets of positive group switches for inversion process, one set of switches is regular inverter switches called vertical positive group switches, and the second set is anti-series switches, which are horizontally connected for direct or single-stage conversion.Originality/valueCharacteristics, principles and implementations of proposed DC–AC 3Ø conversion system and its PWM strategy are analyzed. Through experimental outputs, the effectiveness and viability of the proposed solutions are validated.

Impact of growth parameters on the background doping of GaN films grown by ammonia and plasma-assisted molecular beam epitaxy for high-voltage vertical power switches

We report on ammonia and plasma-assisted molecular beam epitaxy (NH3-MBE and PAMBE) grown GaN layers with a low net carrier concentration (Nnet). Growth parameters, such as growth rate, V–III ratio, and plasma power, were investigated on different substrates to study their impact on surface morphology and background doping levels using atomic force microscopy and capacitance–voltage (C–V) measurements, respectively. The elevated growth rates are especially interesting for vertical power switches, requiring very thick drift regions (over 10 μm) with low background concentrations. For our NH3-MBE-grown layers, Nnet shows an almost linear increase with the growth rate. Using a freestanding substrate and at a fast growth rate of 1.4 μm hr−1, a Nnet value as low as 1 × 1015 cm−3 was achieved. For samples grown via PAMBE, the lowest Nnet among samples grown under a Ga adlayer was 2 × 1016 cm−3 for a growth rate of 0.32 μm h−1 on a GaN-on-sapphire template. The results support the use of MBE for growing high-quality GaN material with reasonably fast growth rates maintaining low background doping levels for high-voltage vertical power electronic devices.

Optimized vertical RF-MEMS switch design with a small actuation voltage

A vertical RF-MEMS (Radio Frequency Micro ElectroMechanical Switch) switch design is proposed in this work that features a shunt capacitive configuration and can operate at a very low actuation voltage. Besides operating on a low switching voltage, the switch behold a small value of insertion loss in Up (ON) state and offers a towering isolation factor in Down (OFF) state. A horizontal structure of bridge membrane is used in the proposed design and the switch function (with ON and OFF operating states) is provided by the vertical movement of this membrane structure that is controlled by the electrostatic actuation technique. The actuation pad is centrally fed by a Coplanar Waveguide structure. The switch performance has been analysed over a wide frequency range from 1 to 40 GHz. For obtaining a 1.5 μm vertical displacement of the bridge membrane, a sheer 3.0 Volts of pull-in voltage (VPI) is required. CoventorWare and HFSSv13 tools are used in this work for designing and analysing the proposed switch. The use of fixed-fixed flexure beam configuration is chosen for switch design. Simulation results showcase excellent RF characteristics with isolation factor of −47 dB (at 32.5 GHz) and insertion loss in range of −0.01 to −1.10 dB (for 1−40 GHz frequency).

(Invited) GaN Homoepitaxial Growth and Substrate-Dependent Effects for Vertical Power Devices

Vertical GaN power switch technology is expected to be utilized in next-generation medium to high voltage power converters due to the low ON-resistance and high breakdown voltage enabled by the improved critical electric field and mobility compared to Si and SiC-based devices. As large area substrates have become available by hydride vapor phase epitaxy (HVPE) and ammonothermal growth, the properties of nitrides are no longer dominated by defects introduced by heteroepitaxial growth, allowing recent realization of several fundamental vertical power devices, including diodes with edge termination, trench MOSFETs, and CAVETs. However, additional materials challenges are coming to the forefront that need to be understood and surmounted in order to allow vertical GaN power devices to achieve their full potential, notably the realization of repeatable thick drift layers with low background doping. To enable this, a deeper understanding of substrate preparation and the effects of the substrate and growth initiation on the characteristics of the epitaxial layers is required for MOCVD growth of homoepitaxial films. We investigate these effects on epi morphology, uniformity, and impurity incorporation by growing simultaneously on wafers from different vendors. The goal of this work is to detect and identify defects in GaN substrates with a series of quick, non-destructive, inexpensive techniques with capabilities of mapping whole wafers. We have characterized multiple substrates from over eight suppliers and the homoepitaxy grown on those substrates. All the substrates had nominally similar as-received specifications (resistivity, thickness, off-cut angle, bow, surface finish). The substrates were evaluated with a variety of techniques including Raman spectroscopy, photoluminescence, white light interferometry, and Nomarski imaging, enabling to detection of different concentrations of grain boundaries, sample impurities, point defects, v-shaped pits, polishing defects, crystal stress damage, and non-uniform insulating and conducive regions. The substrates can be characterized in two different categories: those with uniform characteristics, including carrier concentration, and those without. Comparing these results to those from homoepitaxial growth on the same wafers, the effects are both subtle and overt. Macroscopic surface morphology, which has shown a direct correlation to leakage current, copies and exaggerates that of the underlying substrate. Photoluminescence of the homoepitaxial surface along with Raman spectroscopy show that non-uniformities in the substrate carrier concentration can continue into the epitaxy. Following optical characterization, vertical Schottky diodes were fabricated to quickly evaluate device performance. While most of the films showed the ability to withstand high electric fields, those with more uniform properties in the substrate also showed more uniform electrical properties. These results show that the bulk substrates enable the path to high voltage vertical devices, but also show the significant influence that substrates can play in device performance.

Modification of the Electronic Transport in Atomically Thin WSe2 by Oxidation

AbstractAtomically thin tungsten diselenide (WSe2) is a promising 2D semiconductor for nanoelectronics and optoelectronics. Using UV ozone and low‐power O2 plasma treatments, it is demonstrated that the formation of WSe2(1−x)O2x (WSeyOx) leads to hysteretic behavior in vertical transport measurements and also enables to an improvement in the p‐type transfer characteristics in lateral transport measurements. The amount of oxidation correlates well with the resistive switch behavior in oxidized WSe2/graphene, and WSeyOx formation under the electrical contact of the horizontal devices leads to increased p‐branch on/off by 100×. In addition to its effect for residue removal, oxidation on field effect transistor channel also helps mitigate n‐type dominated transfer characteristics of WSe2 commonly seen on sapphire. It is demonstrated that light oxidation of WSe2 is a multifunctional post‐growth treatment that enables vertical resistive switch junctions, contact improvement, and continuous tuning of transistor transport properties.

Analyzing the Effects of Aluminum-Doped ZnO and Ag Layers for the Transparent Electrode Vertical PCSS

To figure out the effects of aluminum-doped ZnO (AZO) and Ag layers for the transparent electrode vertical (TEV) photoconductive semiconductor switch (PCSS) reported in our previous works, several different structures of high power, new vertical, extrinsic-triggered PCSS were designed and their performances are presented. All the PCSSs were fabricated on the vanadium compensated semi-insulating (VCSI) 4H-SiC substrates. The ON-state performance of all device versions was characterized by a test circuit without load resistor. Among all structures, the version with AZO transparent window, AZO subcontact layer, and silver mirror reflector has been testified to be the most reasonable structure, and shows the best results as well. Its minimum ON-state resistance is 6.11 Ω at the optical power density of 2.62 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The factor for the best ON-state performance of this structure is attributed to the improvement of utilization efficiency of laser energy, and good contact between the AZO and SiC substrate.

Bipolar AC (Bipac) Switch With Buried Layer for Specific AC Mains Applications

A new vertical bipolar bidirectional switch (Bipac) with a buried layer is proposed for specific ac mains applications (230 V-50 Hz). It is mainly dedicated for the low load current ones (0.5 Arms) and must support a voltage of 750 V in the blocking state. Moreover, the Si-chip area must not exceed 10 mm2. The study of the new proposed Bipac structure is carried out using 2-D Sentaurus physical simulation. The operating principles are first validated, and then the physical and geometrical parameters of the buried layer are determined to meet the specifications. As compared to the classical Bipac, the Bipac with a buried layer exhibits a much higher current gain that makes it more attractive in replacing the triac in the targeted applications.