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In a line-commutated converter based high-voltage direct-current (LCC-HVDC) system, the inverter control system usually includes constant extinction angle (CEA) controller, constant current (CC) controller, current error controller (CEC), and voltage-dependent current order limiter (VDCOL). However, the interaction influence of multiple controllers may cause repetitive commutation failure (CF). For this purpose, this paper deeply investigates the mechanism and the influencing factors of repetitive CF caused by controller interaction. It is found that the lower limit value of CEA controller can affect the control switching process and thus the probability of repetitive CF. Besides, the minimum gamma measurement (MGM) unit prevents the system from acquiring the real extinction angle in time, which results in the DC current fluctuation during the recovery process. Moreover, the probability of control-induced repetitive CF is much higher when the HVDC inverter is connected to a weak AC system or the AC fault is not serious but not cleared in time. Based on the above analyses, an improved control method is proposed for recovery performance improvement, which is mainly realized by modifying the lower and upper limits of the CEA controller during recovery. Finally, the simulation and experimental results verify the theoretical analyses and the proposed control method. [ABSTRACT FROM AUTHOR]

During the test of microelectromechanical system (MEMS) devices, calibration of test cables, loads and test instruments is an indispensable step. Calibration kits with high accuracy, great operability and small loss can reduce the systematic errors in the test process to the greatest extent and improve the measurement accuracy. Aiming at the issues of the conventional discrete calibration piece unit, which presents cumbersome calibration steps and large system loss, an integrated electronic calibration chip based on frequency microelectromechanical system (RF MEMS) switches is designed and fabricated. The short-open-load-through (SOLT) calibration states can be completed on a single chip, step by step, by adjusting the on–off state of the RF MEMS switches. The simulation results show that the operating frequency of the electronic calibration piece covers the range of DC~26.5 GHz, the insertion loss in through (thru) state is less than 0.2 dB, the return loss is less than 1.0 dB in short-circuit and open-circuit states, the return loss under load-circuit state is less than 20 dB and its size is only 2.748 mm × 2.2 mm × 0.5 mm. This novel calibration chip design has certain esteem for advancing calibration exactness and effectiveness. [ABSTRACT FROM AUTHOR]

Design of Inductive Power Transfer (IPT) controller to tune EV charging level in a wide range is of great importance. The IPT power level controller is proposed to regulate the power transfer rate by modulating the active state and zero state counts of the converter. During active states, energy injection is applied to the IPT compensation tank which increases the IPT resonant current; during the zero state; no injection occurs, and the resonant current of IPT tank is in free oscillation. The FPGA-based IPT power controller is designed to be applied on single stage AC-AC matrix converter which allows direct connection to the main grid without any need of DC conversion; the controller is also operational in dual-stage AC-DC-AC topologies. The proposed IPT power controller is self-tuned without any need to wireless communication channel and offers more simplicity, higher speed, ease of implementation and lower cost. The efficiency up to 90.73% is achieved for the proposed IPT controller thanks to soft-switching (ZCS and ZVS). Finally, ModelSim-Quartus simulation results as well as experimental validation results are provided. [ABSTRACT FROM AUTHOR]

To operate a converter at cryogenic temperatures, understanding the characteristics of power semiconductor devices is critical. This paper investigates the temperature and current dependence of the dynamic performance of five types of SiC power MOSFETs at 77 K. The turn-on and turn-off lasting time and the corresponding switching energy loss are extracted from a series of double-pulse tests. The transient peak voltage of cryogenic MOSFETs is lower, but the switching time is higher than the room-temperature ones. Moreover, power-exponential functional relations with the operating currents are found in the experiments. These results obtained lay some technical bases for exploring superconducting power electronics. [ABSTRACT FROM AUTHOR]

Integrated photonics is a cutting-edge field that merges optics and electronics on a single microchip, revolutionizing how we manipulate and transmit light. Imagine traditional bulky optical systems condensed onto a chip smaller than a fingernail, enabling faster communication, more efficient sensors, and advanced computing. At its core, integrated photonics relies on guiding light through waveguides etched onto semiconductor substrates, analogous to how wires conduct electricity in traditional electric circuits. These waveguides can route, modulate, and detect light signals with unprecedented precision and speed. This technology holds immense promise across various domains. Despite its immense potential, integrated photonics faces challenges, including manufacturing complexities and integration with existing electronic systems. However, ongoing research and advancements continue to push the boundaries, promising a future where light-based technologies seamlessly integrate into our everyday lives, powering a new era of innovation and connectivity. [ABSTRACT FROM AUTHOR]

Finite control set model predictive control (FCS-MPC) strategies for power conversion devices benefit from extending the prediction horizon length. Solving this problem relies on the definition of the underlying integer least-squares problem. Sphere decoding algorithm (SDA) has been extensively used in previous works as an approach to solve this problem. In this article, a parallel and fully scalable K-best SDA hardware design is proposed as an alternative. The K-best SDA establishes a different breadth-first search strategy, which addresses some of the main drawbacks of the SDA. Through experimental tests based on an uninterruptible power supply, the K-best SDA performance for long prediction horizon FCS-MPC is assessed and verified. Results demonstrate key beneficial aspects through which the K-best SDA is capable of rendering an improved control performance when compared to the conventional SDA. [ABSTRACT FROM AUTHOR]

We study the problem of off-policy evaluation in the multi-armed bandit model with bounded rewards, and develop minimax rate-optimal procedures under three settings. First, when the behavior policy is known, we show that the Switch estimator, a method that alternates between the plug-in and importance sampling estimators, is minimax rate-optimal for all sample sizes. Second, when the behavior policy is unknown, we analyze performance in terms of the competitive ratio, thereby revealing a fundamental gap between the settings of known and unknown behavior policies. When the behavior policy is unknown, any estimator must have mean-squared error larger—relative to the oracle estimator equipped with the knowledge of the behavior policy— by a multiplicative factor proportional to the support size of the target policy. Moreover, we demonstrate that the plug-in approach achieves this worst-case competitive ratio up to a logarithmic factor. Third, we initiate the study of the partial knowledge setting in which it is assumed that the minimum probability taken by the behavior policy is known. We show that the plug-in estimator is optimal for relatively large values of the minimum probability, but is sub-optimal when the minimum probability is low. In order to remedy this gap, we propose a new estimator based on approximation by Chebyshev polynomials that provably achieves the optimal estimation error. Numerical experiments on both simulated and real data corroborate our theoretical findings. [ABSTRACT FROM AUTHOR]

With the development of power system electronization, distributed new energy generation-based DC microgrid system has become a hot spot of the current research. Aiming to implement the collection, transformation and transmission of the new energy sources, the dual active bridge (DAB) converter has become a key energy conversion device. Aiming to promote the transmitted efficiency for such DAB converter, a deep reinforcement learning (DRL) optimization scheme with the triple-phase-shift (TPS) is proposed. Specifically, the deep deterministic policy gradient (DDPG) algorithm is used for solving optimal solutions with the minimum power losses. Then, the trained DDPG agent is used as a fast surrogate predictor, which giving the suitable control decisions under whole operation conditions. The main control objective is to minimize the power losses for getting the target maximum efficiency. Besides, the soft switching constrains are added to the DDPG algorithm. Based on this, the proposed optimized method can be used for different operation conditions with excellent performance. The operation principles, the loss analyses, and the training consideration and evaluation of the DDPG algorithm are given. Finally, simulation and experimental results using a 200 W hardware prototype are displayed and compared to prove to effectiveness of theoretical analysis. [ABSTRACT FROM AUTHOR]

Railway point machines (RPMs) is one of the most vital devices closely related to the efficiency and safety of train operation. Considering the advantages of contactlessness and easy-to-collect of sound signals, a novel sound-based fault diagnosis method for RPMs is proposed. First, fractional calculus is introduced to wavelet packet decomposition energy entropy (WPDE). Fractional WPDE (FWPDE) is then proposed, which is verified to be a more effective tool for fault feature representation. Second, coarse-grain process is firstly introduced to FWPDE. Novel feature named multi-scale FWPDE is developed, which can significantly improve fault diagnosis accuracy. Third, to select optimal feature set and optimize the hyperparameters of support vector machine (SVM) at the same time, a synchronous optimization strategy based on binary particle swarm optimization (BPSO) is presented, which can further improve the diagnosis accuracy. The superiority and effectiveness of the proposed method are verified by comparing to some existing fault diagnosis methods. The diagnosis accuracies of reverse-normal and normal-reverse switching processes reach 99.33% and 99.67%, respectively. Especially, the proposed method is suitable for diagnosis of similar faults, which can also provide reference for similar research fields. [ABSTRACT FROM AUTHOR]

It is important to explore better alternatives to CMOS to sustain Moore’s law far in the future. One option is to integrate non-volatile spin devices, such as magnetic tunnel junction (MTJ), with the existing CMOS technology to augment its capability. This article presents five approximate 1 bit full adders for applications where accuracy can be traded for energy, speed, and area. The application of an approximate adder is demonstrated in image processing for smoothening an image. Three of these adders are fully non-volatile, one is partially volatile, and one is fully volatile. All the adders use SRAM-based sense amplifier (SA) to reduce sensing energy and hardware count. To reduce the delay, some of the adders utilize the parallel connection of logic devices (MTJ or MOSFET) in the logic tree. All the adders are simulated using 45 nm CMOS predictive technology model (PTM) and perpendicular magnetic anisotropy (PMA) CoFeB/MgO/CoFeB MTJ model with HSPICE simulator. After performing simulations, results show that the proposed fully non-volatile approximate adder (AXFA4) performs exceptionally well against its existing counterpart AX_MFA2 in terms of the energy-delay product (EDP) and the area-delay product (ADP) with a decrement of 84% and 80%, respectively. All the adder designs compute sum at 75% and carry at 100% accuracy, respectively. [ABSTRACT FROM AUTHOR]

This article presents a new hybrid three-phase cascaded modular multilevel inverter developed with a reduced switch count concept for harvesting renewable energy. The basic module of the proposed inverter consists of six switches, three asymmetric dc links, and two blocking diodes. The inverter can generate six positive voltage states, which are negatively polarized by the end-side H-bridge unit. As a result, a higher number of voltage levels are obtained with a minimum number of switches that ensure reduced total harmonic distortion in the grid current. Additionally, the proposed inverter can operate at a comparatively lower switching frequency, which decreases the switching losses. Most of the switches in each individual module conduct for a small period resulting in low conduction losses. The reduced switch count with the low switching and conduction losses increases the compactness and the efficiency of the proposed inverter. Multiple high-frequency magnetic links are utilized for the dc sources required for the proposed inverter to achieve inherent dc-link voltage balancing ability and galvanic isolation. The performance of the proposed inverter is validated by simulation and experimental investigations. [ABSTRACT FROM AUTHOR]

Abstract The utilization of switched inductors, involving parallel charging and series discharging of inductors, is extensively embraced in diverse DC–DC converters for attaining high voltage gain; nevertheless, the stress on switch voltage and diode current escalates considerably with an increased count of inductors integrated into the switched inductors network. In the classical multistage switched inductor converter, the switch voltage aligns with the output voltage, and the diode experiences a high current as the number of stages increases. This research recommends a DC–DC multistage converter for energy conversion and high voltage gain with low stress. In this paper, a novel multistage switched inductor converter is introduced and designed to attain higher voltage gain while mitigating the stresses on switch voltage and diode current. The proposed circuit is created by replacing the standard multistage switched inductor converter's possible diodes with power switches. All of the switching devices are connected in such a way that the output voltage and input current are shared by all of the switches and diodes, respectively. As a consequence, the voltage stress on switches and the current stress on diodes are comparatively low, resulting in a high efficiency compared to a typical multistage switched inductor converter. It's interesting to note that the proposed converter and a typical multistage switched inductor converter both require the same amount of components. Different operation modes, analysis, a non‐ideal model, and a comparison of the suggested and recently constructed converters are discussed. The effectiveness and performance of the circuit are validated experimentally.

In a previous paper (Part 1) the authors have performed the simulative evaluation of the life lost by HVDC extruded cables subjected to long TOVs occurring in VSC HVDC cable systems. The conclusions were that it cannot be completely ruled out that the field levels and the duration of such TOVs are a potential threat to certain cable designs, and tests other than Load Cycling Type Tests after CIGRÉ Technical Brochure 496 could assess quantitatively the potential threat associated with long TOVs. For these reasons, in this Part 2 superimposed switching impulses applied during Type Tests after TB 496 are analyzed in order to check if such impulses might be equivalent to long TOVs as for their electro-thermal stress effects on extruded insulation. The analysis is similar to that carried out for long TOVs in Part 1, i.e., it consists of: calculating the electric field during superimposed switching impulses; comparing it with the field during long TOVs; calculating with Miner's law of cumulated damage the life lost during superimposed switching impulses and comparing it with the loss of life during TOVs. A brief literature survey of potential high field effects during long TOVs is also reported. [ABSTRACT FROM AUTHOR]

An improved two-stage model predictive current control (MPCC) for three-phase three-level converters in the paper, which can simultaneously achieve common-mode voltage (CMV) reduction, effective dc-link capacitor voltage control, and decreased computational burden, is proposed. Compared to the other current control strategies, it has the capability of handling multiple control objectives and possesses a simple structure. Furthermore, it greatly reduces the CMV since the peak CMVs of all the candidate voltage vectors are constrained to be less than one sixth of the dc-link voltage. In addition, an optimal two-stage voltage vector selection mechanism is employed in the proposed method. It helps to significantly reduce the computational complexity. Simulation and experimental results are provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents Space Vector Modulation (SVM) sequences that reduce Common Mode Voltage (CMV) in Dual Three-phase Asymmetrical Induction Motor (DTAIM). At first, two existing SVM techniques such as Reference SVM (RSVM) and CMV1 are studied. Additionally, three new switching sequences are developed as CMV2, CMV3 and DCMV3, which reduce peak magnitude of CMV by 66.8% in comparison with RSVM technique. In SVM techniques, to obtain least CMV, zero vectors are usually replaced by two opposite large Active voltage Vectors (AV) with equal time duration. In such topologies like CMV1, total six AVs are utilized to synthesize the reference vector. The proposed SVM technique CMV2 utilizes only five large AVs to synthesize the reference vector and reduces CMV. Selection of five neighbouring AVs is reflected in reduction of harmonic flux trajectories and stator current ripple in proposed techniques. Additionally, two more switching sequences (CMV3 and DCMV3) are developed related to utilization of specific zero voltage vectors in all sectors (7 and 56) that produce zero CMV. These two switching sequences also provide easy implementation feature during the development of c-code program. In this study, CMV and stator current ripple are considered as performance parameters for different SVM techniques. All SVM techniques are analysed by analytical results, computer simulations, and using prototype test setup of DTAIM fed by Dual Three-phase Voltage Source Inverters (DTVSIs). [ABSTRACT FROM AUTHOR]

Mobile edge computing becomes a promising technology to mitigate the latency of various cloud services. In addition, network function virtualization (NFV) has been shown a great potential in reducing the operational cost of cloud services while enhancing the flexibility of virtual network function deployments, by implementing dedicated hardware network functions as pieces of software in generic servers. Recently, the GPU acceleration has been investigated to speed up flow processing in virtual network functions (VNFs), by leveraging the parallelism of GPUs. VNFs that need accelerations prefer to stay at cloudlets (locations) equipped with GPUs. However, little attention has been paid for the VNF placement that takes into account GPU-affinity in cloudlets of mobile edge clouds. In this paper, we consider the affinity-aware throughput maximization problem in a mobile edge cloud via leveraging the parallelism on GPUs for user requests with VNF requirements. We consider two types of affinities in the VNF placement: The soft-affinity that allows VNFs to be executed by either CPUs or GPUs in cloudlets; and the hard-affinity that only allows VNFs to be placed to the GPUs of a specified set of cloudlets. We formulate two corresponding VNF placement problems in a mobile edge cloud. Specifically, we first propose an exact solution to the soft-affinity throughput maximization problem by formulating an Integer Linear Program (ILP). We then propose an efficient algorithm for the problem, by proposing a randomized algorithm with a provable approximation ratio for the hard-affinity-aware throughput maximization problem and extending the proposed approximation algorithm to the soft-affinity throughput maximization problem. Furthermore, assuming that user requests arrive into the mobile edge cloud one by one without the knowledge of future arrivals, we devise an online algorithm with a good competitive ratio for this dynamic hard-affinity-aware throughput maximization problem. Finally, we evaluate the performance of the proposed algorithms, through simulations and implementations in a real test-bed. Experimental results show that the performance of the proposed algorithms outperform their existing counterparts and achieve higher throughput. [ABSTRACT FROM AUTHOR]

The electromagnetic repulsion model of 400 V/630 A/12.5 kA fast vacuum transfer switch (FVTS) is established using finite element method. The speed and characteristics of the contact bounce of the FVTS are taken as constraints, and the objective is to keep the reliable opening of the mechanism with allowable bounce. The deceleration of the fast operating mechanism in the process of opening and closing is realized by applying the reverse electromagnetic repulsion force. Moreover, the simulation results demonstrate that the electromagnetic buffer effect is available, and the allowable bounce opening of the operating mechanism has been obtained. Furthermore, this paper compares the buffering effects of three kinds of conditions, such as no electromagnetic buffering, 110 V electromagnetic buffering and 220 V electromagnetic buffering. It can be found that the electromagnetic buffering is a necessary part of the 400 V FVTS, and the dynamic characteristics are the optimal scheme when the 220 V electromagnetic buffering is applied. Based on the results of simulation, a FVTS experimental prototype is developed to prove the effectiveness of the design scheme. [ABSTRACT FROM AUTHOR]

In the recently published paper, a switching method has been proposed to deal with the time derivative of the membership functions and less conservative results can be obtained due to this method; however, this method is based on the assumption that the switching times are finite. In this article, this method is further studied and the average dwell-time (ADT) switching technique is applied to ensure the stability if there is no such assumption. In addition, an algorithm is proposed to find the switching controller gains. The final simulation demonstrates the effectiveness of the developed new results. [ABSTRACT FROM AUTHOR]

Considering the advantages of contactless fault diagnosis, a novel sound based fault diagnosis method for railway point machines (RPMs) is proposed. Firstly, a denoising method based on empirical mode decomposition (EMD) is proposed. The useful intrinsic mode functions (IMFs) are selected using kurtosis and energy criteria to reconstruct the denoised signal. Then, multi-scale fractional permutation entropy (MFPE) is proposed inspired by fractional calculus, which is more powerful than the classical multi-scale permutation entropy (MPE). And a two-scale algorithm is developed to avoid neglecting the information contained at the end of the signals in the coarse-graining process. Finally, the feasibility and superiority of the proposed method (D-FMPE-T) based on denoising method and two-scale algorithm are verified using support vector machine optimized by particle swarm optimization (PSO-SVM) through comparing with some commonly used feature extraction and classification methods. Besides, CWRU is also utilized for verification of the superiority of the proposed method. Experiment results show that the proposed method performs best. The identification accuracies on normal-reverse and reverse-normal switching processes, and CWRU data sets reach 99.3%, 99%, and 99.17% respectively, demonstrating the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Identifying the location of partial discharges (PDs) and providing clear information on insulation vulnerabilities in power systems can help utility companies to improve their maintenance efficiency. This paper presents a PD monitoring and locating system for medium-voltage switchgears using a set of transient earth voltage (TEV) detectors. A time-of-flight methodology was used to identify the switchgear affected by PD among a row of switchgears. A time sharing access mechanism, which was implemented by multiple high-frequency surface mounting relays integrated into each TEV detector, was applied to automatically identify the site of PD and minimize the number of expensive high-speed acquisition cards. The operation principle and implementation of the modular system were formulated, and the efficiency of the proposed system in identifying the switchgear with PD among three 10 kV metal-clad switchgears was confirmed experimentally. [ABSTRACT FROM AUTHOR]

A mechanical switch can be used instead of a power electronic load commutation switch in orderto reduce the losses during normal power flow in standard hybrid DC circuit breakers. The success of current commutation in such hybrid breakers depends on the arc voltage formed across the contacts in the mechanical switch. The behaviour of rapidly elongated, wall constricted arcsgenerated during the opening of an ultra-fast mechanical switch in the air is studied here. The voltage-current characteristics of the generated arcs are obtained for steady state contact opening velocities of 6, 11 and 21 m/s. It is found that the arc voltage at a given current and contact separation increases with the contact opening velocity. It is shown that stationary,zero-contact-velocity characteristics can not be used to accurately quantify the voltage build-up in fast elongating arcs in hybrid breakers. A best-fitting black-box equation for the dynamic arc characteristics is presented for the tested velocities. The obtained voltage-current characteristics are used as input to simulate the current commutation process in a 12 kV hybridDC circuit breaker case-study. Different scenarios of current commutation failure related to the arc voltage build up are identified. It is shown that these failures scenarios can be avoided by increasing the contact opening velocity. [ABSTRACT FROM AUTHOR]

The implementation of finite-control-set model predictive control (FCS-MPC) in voltage source inverters (VSIs) can make the system suffer from poor current harmonics performance, which may complicate the design of the required AC filter. To overcome this shortcoming, a carrier-based modulated model predictive control (CB-MMPC) strategy is proposed in this paper. This method enables the utilization of existing PWM modulation techniques with FCS-MPC, where a modulation waveform with zero-sequence signal injection is generated and compared to a triangular carrier wave, while optimizing the selection of the switching states. As it is shown, the studied CB-MMPC strategy not only considerably improves the current total harmonic distortion (THD) but also attains the performance of fast current dynamic response and robustness as the traditional FCS-MPC. Herein, the detailed implementation of the CB-MMPC control strategy is given, while considering its application to the current feedback control loop of a three-phase three-wire two-level VSI modulated at constant switching frequency. Finally, PLECS circuit simulation and a 3-kW VSI prototype are used to verify the superiority and the effectiveness of the presented CB-MMPC strategy. This is also benchmarked to the FCS-MPC and dead-beat based controllers. [ABSTRACT FROM AUTHOR]

In this paper, the containment problem with nonconvex velocity constraints is studied for second-order discrete-time multiagent systems. A distributed projection-based algorithm is proposed for all followers to be gathered in the convex area formed by multiple stationary leaders. It is revealed that the algorithm can solve the velocity-constrained containment problem with communication delays and switching networks provided that each follower has at least a directed path from some leaders to itself in the union of graphs. The main analysis approaches include model transformation techniques, Lyapunov function, and convexity analysis. A simulation example is also included to elucidate the obtained result. [ABSTRACT FROM AUTHOR]

Operational performance in the low-voltage distribution network (LVDN) can be undermined by its inherent unbalances, which may become worse as the penetration of rooftop solar continuously increases. To address this issue, load balancing via phase-reconfiguration devices (PRDs), which can change phase positions of residential customers as required, provides a cost-efficient option. However, most reported approaches to control PRDs require that demands of all residential customers are available, which are not viable for many LVDNs without smart meters or advanced metering infrastructure (AMI) installed. To bridging the gap in this field, this paper proposes a novel method to control PRDs purely based on measurable data from PRDs, and its controller. Based on limited information, sensitivity analysis in the network with PRDs is studied, followed by the optimization model that comprehensively considers operational requirements in the network. Moreover, slack variables are introduced to the model, and penalized in the objective function to assure either a strategy that is secure or with minimized violations can always be provided. The model is a challenging mixed-integer non-convex programming (MINCP) problem, which is reformulated as an efficient solvable mixed-integer second-order cone programming (MISOCP) based on exact reformulations or accurate linear approximations. Simulations based on two modified IEEE systems, and a real system in Australia demonstrate that an efficient strategy can be provided to mitigate unbalances in the network. [ABSTRACT FROM AUTHOR]

In this brief a brief tutorial of charge pump topologies for management of self-powered nodes in ultra-low-power applications, such as Internet of Things nodes, is presented. It aims to provide to the designer guidelines to choose the most suitable solution, according to the given design specifications. After a brief historic evolution, the main design equations of charge pumps and a collection of the recent proposed topologies and regulation schemes are discussed, allowing for qualitative insight into the state-of-the-art of integrated topologies. [ABSTRACT FROM AUTHOR]

Abstract As a key component of high‐performance switches and routers, the packet forwarding engine (PFE) is mainly responsible for selecting the appropriate output port for tens of thousands of packets within an extremely short time frame. However, the performance of PFE is determined by the selected group membership algorithm. This paper puts forth a hybrid strategy–caching scalar‐pair and vectors routing and forwarding (CSVRF), consisting of virtual output port bitmap caching (VOPBC) and fractional‐N SVRF to address major multicast forwarding issues such as scalability by using content addressable memory. In CSVRF, a virtual output port bitmap cache is introduced, which includes the most popular combinations of output port bitmap and divides the big scalar‐pair into N sub‐groups to achieve parallel compute and the reusability of less bit‐length prime. The results demonstrate that the memory space and the forwarding latency are effectively reduced compared with previous work. In space efficiency, it only required 10% memory space compared with the original SVRF/fractional‐N SVRF, decreased 10% memory usage compared with pure VOPBC and nearly improved 1 to 4 orders of magnitude of packet processing time compared with the original SVRF and the fractional‐N SVRF respectively.

A 1,2,3-triazole-based chemosensor is used for selective switching in logic gate operations through colorimetric and fluorometric response mechanisms. The molecular probe synthesized via "click chemistry" resulted in a non-fluorescent 1,4-diaryl-1,2,3-triazole with a phenol moiety (PTP). However, upon sensing fluoride, it TURNS ON the molecule's fluorescence. The TURN-OFF order occurs through fluorescence quenching of the sensor when metal ions, e.g., Cu2+, and Zn2+, are added to the PTP-fluoride ensemble. A detailed characterization using Nuclear Magnetic Resonance (NMR) spectroscopy in a sequential titration study substantiated the photophysical characteristics of PTP through UV-Vis absorption and fluorescence profiles. A combination of fluorescence OFF-ON-OFF sequences provides evidence of 1,2,3-triazoles being controlled switches applicable to multimodal logic operations. The "INH" gate was constructed based on the fluorescence output of PTP when the inputs are F− and Zn2+. The "IMP" and "OR" gates were created on the colorimetric output responses using the probe's absorption with multiple inputs (F− and Zn2+ or Cu2+). The PTP sensor is the best example of the "Write-Read-Erase-Read" mimic. [ABSTRACT FROM AUTHOR]

In a radio frequency (RF) system, it is possible to use variable inductors for providing tunable or selective frequency range. Variable inductors can be implemented by the microelectromechanical system (MEMS) process or by using transistors as switches to change the routing of coils or coupling quantities. In this paper, we investigated the design method of a variable inductor by using MOS transistors to switch the main coil paths and the secondary coupled coils. We observed the effects of different metal layers, turn numbers, and layout arrangements for secondary-coupled coils and compared their characteristics on the inductances and quality factors. We implemented two chips in the 0.18 m CMOS process technology for each kind of arrangement for verification. One inductor can achieve inductance values from about 300 pH to 550 pH, and the other is between 300 pH and 575 pH, corresponding to 59.3% and 62.5%, respectively, inductance variation range at 4 GHz frequency. Additionally, their fine step sizes of the switched inductances are from 0.5% to 6% for one design, and 1% to 12.5% for the other. We found that both designs achieved a large inductance tuning range and moderate inductance step sizes with a slight difference behavior on the inductance variation versus frequency. [ABSTRACT FROM AUTHOR]

Time-Sensitive Networking (TSN) has enabled a lot of advancements in industrial automation, aviation, tactile networking, and other ad-hoc networking applications. The bounded latency, reliability, and self-recovering mechanisms for a network are some of the core attributes of the TSN architecture. The reliability of bench-marking of a given TSN architecture, when done with simulators, will not match with that of hardware systems. But the TSN hardware needs more capital investment along with more development time as it involves understanding the hardware-specific parameters. The research in this paper has solved this shortcoming by implementing an open-source and secured SDN(Software Defined Networking)-based TSN framework integrating IEEE’s 802.1 Qbv and 802.1Qcc standards. The novelty of implementation involves i) Realization of Centralized User Configuration (CUC), Centralized Network Configuration (CNC) with open source tools. ii) An algorithm called Dynamic TSN Path Finder (DTPF) is implemented for automatically identifying TSN edges participating in TSN flow. iii) Emulation of hardware environment leveraging Linux-based queuing disciplines and traffic shapers. This unique open source-based TSN architecture is then tested with both TSN and Non-TSN traffic, to demonstrate the gating logic and the delay characteristics based on queuing discipline when applied to virtual queues.

The emerging paradigms of Beyond-5G (B5G), 6G and Future Networks (FN), will capsize the current design strategies, leveraging new technologies and unprecedented solutions. Focusing on the telecom segment and on low-complexity Hardware (HW) components, this contribution identifies RF-MEMS, i.e., Radio Frequency (RF) passives in Microsystem (MEMS) technology, as a key-enabler of 6G/FN. This work introduces four design concepts of RF-MEMS series ohmic switches realized in a surface micromachining process. S-parameters (Scattering parameters) are measured and simulated with a Finite Element Method (FEM) tool, in the frequency range from 100 MHz to 110 GHz. Based on such a set of data, three main aspects are covered. First, validation of the FEM-based modelling methodology is carried out. Then, pros and cons in terms of RF characteristics for each design concept are identified and discussed, in view of B5G, 6G and FN applications. Moreover, ad hoc metrics are introduced to better quantify the S-parameters predictive errors of simulated vs. measured data. In particular, the latter items will be further exploited in the second part of this work (to be submitted later), in which a discussion around compact modelling techniques applied to RF-MEMS switching concepts will also be included. [ABSTRACT FROM AUTHOR]

This article proposes a novel control for the multiple-input, single-inductor, multiple-output dc–dc converters. It is digitally and discretely implemented, which can have an outstanding performance in low-power applications so that at the power of 10 mW, it has an efficiency of 92.5%. Conventionally, in this power range, an attempt is made to take advantage of an analog design that is flexible. Thus, a fully programmable (software designed) converter with digital design using a microcontroller is in great demand. This converter design basis is to deploy the microcontroller's central processing unit (CPU) as little as possible. Also, it only turns on the CPU when necessary to be employed in low-power, portable systems, e.g., energy-harvesting technologies. Therefore, construction costs are significantly reduced. Depending on the energy level of the inputs, they can simultaneously be utilized to charge the outputs. This article uses stability analysis, time-multiplexing control method, and variable-frequency pulsewidth modulation in the proposed control design. Each output can be charged with different frequencies according to its load, and the maximum switching frequency is equal to 10 kHz. Also, the proposed technique for zero-current switching has been digitally implemented; it can be utilized to determine the optimal value of the inductor discharge duty cycle based on the inductor's left-side voltage. Comparative simulations and experimental results reveal the superiority and practicality of the proposed approach. [ABSTRACT FROM AUTHOR]

A direct speed control strategy based on finite control set model predictive control (FCS–MPC) with a voltage smoother is presented herein. In the proposed concept, a finite set of smoothed voltage vectors characterized by an adjustable amplitude and a movable origin is introduced as voltage candidates in the FCS–MPC scheme. The controller predicts the future current and speed and outputs the optimal smoothed voltage using pulse-width modulation. Owing to this control scheme, an abrupt change in the output voltage, which causes a large current ripple, is avoided without additional computational costs. Simulation and experimental results obtained using a permanent magnet synchronous motor fed by a two-level three-phase inverter show that the proposed method effectively reduces the current ripple while achieving a high dynamic drive compared with the conventional FCS–MPC scheme. [ABSTRACT FROM AUTHOR]

The current error is hard to avoid for finite control set model predictive current control (FCS-MPCC) in nine-phase open-end winding permanent magnet synchronous motors. To overcome this problem, an online virtual voltage vector (V $^{3}$) synthesis strategy is proposed in this article. First, a group of V $^{3}$ s without harmonic voltage components are designed as the basic vectors for online synthesis. Then, two adjacent basic V $^{3}$ s and a zero vector are used to synthesize a new V $^{3}$ , which can output arbitrary amplitude and phase angle in the fundamental space. The two basic V $^{3}$ s are directly selected from the located sector of the predicted reference voltage vector (RVV), and their duration ratio can be simply calculated according to the angle of the RVV in the sector. In this way, the zero error is realized between the new V $^{3}$ and RVV. Moreover, an online pulse generation algorithm corresponding to the new V $^{3}$ is proposed, which can calculate the symmetrical pulse sequences in real-time for the multiphase OW drive system without the space vector modulator. Finally, experimental results have verified the effectiveness and superiority of the proposed strategy, in comparison to existing FCS-MPCC in multiphase OW motor drive systems. [ABSTRACT FROM AUTHOR]

A dc–dc converter used for fuel cell vehicles should be characterized by a wide voltage-gain range and low input current ripple. In order to meet the above requirements, a new nonisolated dc–dc converter consisting of an active switched-inductor cell, a zero current ripple cell, and a switched-capacitor (SC) cell was proposed in this article. The proposed converter integrates with the advantages of a wide voltage-gain range, zero input current ripple, low voltage stresses across power semiconductors, and common ground structure. Thanks to the use of a zero current ripple cell, not only the input current ripple is reduced but also the energy transfer path of the SC cell is changed, thereby reducing the instantaneous peak current of the SC structure. The operating principles, the characteristics analysis, and the parameter design of the proposed converter are given. In addition, to show the merits of the proposed converter, a comparison study is demonstrated. Finally, a prototype of 400 V, 1000 W/50 kHz is developed to validate the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

This article proposes and studies different sigma–delta ($\Sigma$ $\Delta$) modulation strategies for obtaining a constant common-mode voltage (CMV) by eliminating the CMV level transitions in a five-phase voltage source inverter (VSI). These techniques are based on choosing vectors that generate a constant CMV with values of 0.1 $V_{\text{dc}}$ or –0.1 $V_{\text{dc}}$. Because of the high-switching frequencies used with wide-bandgap semiconductors, pulse-width modulation techniques continually generate high dv/dt values. Therefore, the proposal to combine a $\Sigma$ $\Delta$ modulation strategy with vector selections achieves a constant CMV level due to the elimination of its level transitions, a reduction in conducted electromagnetic interference and a high-efficiency converter operation. The average number of switching per transistor of the VSI is analyzed using the results from MATLAB/Simulink and PLECS simulations. Experimental results are obtained by applying the proposed $\Sigma$ $\Delta$ modulation strategies on a VSI with silicon carbide MOSFETs. The results demonstrate the achievement of the aforementioned features. [ABSTRACT FROM AUTHOR]

In this article, a low computational burden model predictive control (MPC) strategy without weighting factor is proposed for the single-phase cascaded H-bridge CHB converters. To reduce the switching state candidates, a hierarchy control algorithm is proposed. The grid current is controlled by selecting a subregion from the designed 2-D control plane, instead of the entire area. Two vectors are chosen in one sampling period for more accurate tracking. Then, the voltage balancing is achieved by selecting the optimal switching state from the subregion candidates to form the above two vectors. The cost function can be constructed of one variable: load voltage. Therefore, the weighting factor can be eliminated. No tuning or retuning processes are required in the proposed method. To reduce the computational time further, the principle of eliminating the switching state candidates operating the same voltage balancing performance is proposed. Conventional and proposed MPC methods are verified by experimental tests via a laboratory setup of a three-cell connected CHB converter. Steady-state and transient operations demonstrate that the proposed method guarantees less distortion grid current and shorter execution time (reduced from 15 to 3 $\mu s$). Fast response speed to variations in voltage reference and load resistance can be achieved t. [ABSTRACT FROM AUTHOR]

Fault localization is one of the most important issues for modular multilevel converters (MMCs) consisting of numerous switches. This article proposes an isolation forest (IF) based submodule (SM) switch open-circuit fault localization method for MMCs. Based on the continuous sampling SM capacitor voltages, a number of isolation trees (ITs) are produced to construct the IFs for MMCs. Through the comparison of continuous IFs’ outputs, the faulty SM can be effectively localized. The proposed IF-based fault localization method only requires SM capacitor voltages in the MMC to construct concise low-data-volume tree models, and uses sparsity and difference properties of outlier data to localize fault, and accordingly it simplifies calculation complexity. In addition, it does not require the MMC's mathematical models and manual setting of empirical thresholds. Simulation and experiment are conducted, and the results confirm the effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) featuring reactive power ability and common ground (CG) have become much popular in transformerless grid-tied photovoltaic applications. A switched-capacitor (SC) based five-level transformerless inverter configuration is thus proposed in this article, which requires only six switches, one diode, three capacitors, and one input dc voltage supply. Notably, only four power switches are operated in high frequency, thus, the switching losses are reduced. Moreover, the presented topology can effectively tackle the leakage current problem using a CG architecture. A multicarrier phase disposition pulsewidth modulation strategy is employed to achieve reactive power regulation and SC voltage self-balancing. To achieve the neutral point voltage balance of the presented five-level inverter, a simple closed-loop voltage-balancing control method is proposed. The operation principles with modulation strategy and voltage self-balancing of SC are discussed in depth. Comparisons between the proposed and the state-of-the-art MLIs are presented in detail. Finally, experimental tests on a single-phase 1.1-kW prototype validate the appropriate performance of the proposed inverter. [ABSTRACT FROM AUTHOR]

This article presents a novel low-cost, single-switch, high-step-upresonant dc–dc converter with high reliability. The proposed converter topology comprises a low count of components and a simple structure and achieves the low ripple input current characteristic. The inductors in the resonant network participate in the resonant process rather than creating voltage spikes across the switch and likely reverse recovery problems. The circuit operates in the soft-switching condition (ZVS–ZCS conditions in the turn-off and turn-on transitions), leading to a significant reduction of the switching losses. Moreover, employing film capacitors instead of electrolytic capacitors reduces the size of the circuit and improves reliability. The operational principle and comprehensive steady-state analysis in the continuous conduction mode are discussed in detail, alongside the design considerations of the proposed converter. The validity of the theoretical equations is investigated via experiments, achieving maximum efficiency of 97.69% for a converter designed at the input of 24.5 V, the negative output of 200 V, and the maximum powerof 200 W. [ABSTRACT FROM AUTHOR]

[Display omitted] • The free-standing, monolithic and anisotropic graphite networks were constructed by a two-stage, economy, facile expansion process. • The sensitivity of the sensors/switches can be accurately tailored. • The wireless monitoring of human movement was realized by integrating the sensors/switches with microelectronic components. Highly sensitive strain sensors and switches are essential components to wearable electronics in many emerging applications such as personal health monitoring, human–machine interaction, smart robots and intelligent control system. Herein, we report a new highly-anisotropic graphite framework (HAGF) for creating strain sensors and switches with high flexibility, stretchability and sensitivity. The highly anisotropic three-dimensional (3D) graphite structure was fabricated via a facile, low-cost and scalable expansion of commercially-available graphite papers. By controlling the orientation structure and thickness of HAGF, the contact area and switchable conduction path can be tailored to create strain sensors and switches based on HAGF/PDMS composites to achieve a tunable gauge factor between 1.3 and 379, an ultra-high ON/OFF ratio in the order of 1035 with tunable critical switching strain (8 % ∼ 50 %), an excellent long-term repeatability of over 1000 cycles at a peak strain of 50 %, and a stretchability up to 100 %. The potentials of the new sensors and switches are demonstrated by pairing them with the smartphone for tracking and recognition of human motions, offering a new solution to a wide range of portable devices and mobile applications. [ABSTRACT FROM AUTHOR]

The switched-capacitor of boost seven-level active neutral-point-clamped inverter has the large voltage ripple due to its inherent long discharging interval. Aiming at reducing the switched-capacitor voltage ripple and subsequently the capacitance, this article proposes a flexible third harmonic voltage modulation method. In specific, the long discharging interval can be divided into short intervals or even avoided by flexibly regulating the amplitude and phase-angle of third harmonic voltage based on various modulation indexes and power factors. An offline particle swarm optimization algorithm is employed to find the corresponding optimal amplitude and phase-angle of third harmonic voltage, which will further be put into the online look-up table to simplify the real time implementation. Experimental results verified the performance of the proposed modulation method. [ABSTRACT FROM AUTHOR]

This article presents a highly reliable push–pull resonant dc/dc converter for medium-power applications. At medium power, conventional push–pull resonant dc/dc converter experiences a very high current spike at the secondary-side switches, and this spike can destroy the active power components. We eliminate this current spike by connecting clamp diodes to the resonant capacitors. Moreover, the proposed converter achieves fully zero-voltage-switching (ZVS) turn-off at the secondary-side switches when the load exceeds the threshold. Furthermore, the proposed converter is invulnerable to the short-circuit problem at the output. Experimental results are presented to show the effectiveness of the proposed dc/dc converter at the medium power against a conventional solution. [ABSTRACT FROM AUTHOR]

In this article, we propose a switching anti-windup scheme for the aircraft engine control. The linear engine model with asymmetric saturation is first transformed into a switched system, each subsystem of which is subject to symmetric saturation. A state-dependent switching logic is presented to orchestrate the switching among multiple anti-windup compensators. We then establish the sufficient condition to guarantee the regional stability and $\mathcal {L}_{2}$ performance of the resulting closed-loop system. This condition is less conservative since the non-symmetric nature of the saturation nonlinearity can be fully exploited in the control design. Optimization algorithms are further developed for the anti-windup gain design. The theoretical aspect of the proposed method is analyzed rigorously, and the effectiveness is validated through experiments performed on a semi-physical test bed. [ABSTRACT FROM AUTHOR]

This article introduces a new nonisolated soft-switching coupled-inductor (CI) step-up dc/dc converter. The presented topology utilizes a three-winding CI (TWCI) along with a voltage multiplier circuit to increase the voltage conversion ratio without needing a high duty cycle. Using this circuit, a high voltage gain can be achieved without requiring a large number of turns ratio in the CI. The input current ripple of the introduced converter is very low, which is very desirable for renewable energy sources applications. The TWCI also creates an additional design freedom to increase the voltage gain, which indicates more circuit flexibility. Additionally, the voltage stress across the single power switch is limited with the help of a regenerative clamp capacitor. The leakage inductor of the CI is used to create a resonant tank to reduce power losses further. The leakage inductances help provide the zero-current switching conditions for the single power switch and decrease the reverse-recovery issues for all diodes, leading to an efficiency improvement. The operation principle, steady-state analysis, and design considerations are discussed thoroughly. Finally, the theoretical analysis is validated through experimental results obtained from a 200 W prototype with 250 V output voltage. [ABSTRACT FROM AUTHOR]

Unbalanced ac voltages drastically deteriorate the performance of five-level flying capacitor (FC) rectifiers. Without introducing an extra buffering circuit to absorb the second-order oscillating power, it is an incompatible contradiction for realizing both negative-sequence current reduction and second-order voltage ripple suppression. In this article, based on the idea of using FCs in the rectifier to absorb the oscillating power, a second-order voltage ripple suppression strategy for unbalanced ac voltage conditions is proposed. Reducing the negative-sequence currents and suppressing the dc voltage ripples can be simultaneously realized. Simulations and experimental results verified the effectiveness and performance of the proposed scheme well. [ABSTRACT FROM AUTHOR]

Gate driver circuits to ensure proper turn-on and turn-off for power switches are essential parts of a power converter design. They become significantly challenging for multilevel converters, where multiple switches are operated at active voltage domains. The recent favorable use of gallium nitride devices for power switches makes gate driving even more difficult as the switch performance and reliability are very sensitive to the variations of the gate driving signals and power rails compared with traditional power MOSFETs. This article discusses gate driving methods using a multilevel multi-inductor hybrid (MIH) converter as the demonstration prototype to address two key challenges in designing gate drivers: 1) providing level-shifted pulsewidth modulation signals to active voltage domains and 2) powering schemes for gate driver circuits. To solve the first challenge, an optimal use of available half-bridge drivers is proposed to eliminate the need for separate signal isolator chips. This method was implemented and verified in an MIH converter prototype for 48-V point-of-load applications using three different powering schemes for gate drivers, including isolated power modules, regulated supplies from switch blocking voltages, and cascaded bootstrap power rails with regulations. The gate driver techniques and powering schemes are compared experimentally in terms of performance to illustrate their benefits and tradeoffs. [ABSTRACT FROM AUTHOR]

A dual-transformer-based hybrid dual active bridge (DAB) converter for plug-in electric vehicle charging to cope with wide load voltages is introduced in this article. The control degrees of freedom are extended by splitting the leg and transformer of the conventional DAB converter (CDABC) in two parts. Based on the numerical analysis, the full-domain four-variable closed-form optimal trajectories targeting at the minimum root mean square value of the leakage inductor current is attainted, and the unified-segmental control strategy is proposed to handle the working modes shifting without the current inrush. As a result, the conduction losses and switching losses can be significantly reduced in boost mode compared to CDABC. The discussed converter and control strategy are verified by a 1.0-kW prototype. [ABSTRACT FROM AUTHOR]

This article investigates a decoupled vector current control strategy for grid-tied single-phase nine-level Packed E-Cell (PEC) inverters for vehicle-to-grid (V2G) technologies. The control design is based on a loop shaping approach, where performance specifications such as desired closed-loop bandwidth, closed-loop stability, robustness to pure time-delays in control loops/process, and decoupling between direct ($d$) and quadrature ($q$) axis of control signals are specified in the frequency domain. The control design problem is formulated as a convex optimization problem whose solution results in a multivariable controller in the $dq$ framework. The effectiveness of the proposed control strategy in terms of robust stability, current tracking, and improved total harmonic distortion is evaluated by experimental and simulation results under several case studies. The results also show that the designed controller provides the desired transient response as well as decoupling between the $dq$ output currents. [ABSTRACT FROM AUTHOR]

Linear modulation techniques (LMTs) of an asymmetrical six-phase machine (ASPM) with two isolated neutral points synthesize the desired voltage vectors by applying at least five switching states. Different choices of applied voltage vectors, sequences in which they are used, distribution of dwell-times among the redundant switching states give rise to a large number of possible LMTs. It is desirable that these LMTs avoid more than two transitions of a particular inverter leg within a carrier period. Only a subset of existing LMTs of ASPM follows this rule. Through an innovative approach, this article finds a way to account for all possible infinitely many LMTs that follow the rule of at most two transitions per leg. Another important criterion for the selection of an LMT is its current-ripple performance. Therefore, through numerical optimization, this article finds optimal LMTs among the above infinite possible LMTs for all reference voltage vectors in the linear range and for the whole feasible range of a machine parameter. This parameter is related to the leakage inductance of the machine and impacts the current ripple performance of ASPM. An optimal hybrid strategy is proposed with these optimal techniques, which outperforms all existing techniques in terms of the current ripple. The theoretical analysis is validated through simulation in MATLAB and experiments performed up to 3.5 kW on a hardware prototype. [ABSTRACT FROM AUTHOR]

This article presents two techniques to address the reliability issues caused by dv/dt under fast switching conditions of gallium nitride high electron mobility transistors. The first technique called active overdrive voltage control is proposed to adjust the gate driving strength according to the rising speed of the switching node (dv/dt) adaptively and, thus, decrease the dv/dt without increasing too much switching loss. The second technique is three-branch high-voltage level shifter (TBLS), which can improve the dv/dt immunity without compromising the signal transmission speed. The common mode current caused by dv/dt can be copied and then compensated by a transient current provided by the auxiliary branch. Combining the above techniques, a 400 V half bridge gate driver IC is fabricated by silicon-on-insulator BCD process. Compared with the gate driver IC utilizing the conventional open-loop output stage, the proposed gate driver IC reduces the turn-on switching loss by 16.2% for the same level of peak dv/dt at 400 V 10 A application. In addition, the proposed TBLS can achieve the dv/dt immunity up to 100 V/ns meanwhile the propagation delay less than 14 ns, enabling megahertz operation frequency. [ABSTRACT FROM AUTHOR]