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This article proposes an isolated high‐efficiency resonant LED driver with wide‐input voltage range. The proposed converter is developed by integrating LCC resonant converter and buck‐boost converter. In this topology, the LCC network provides many features including the integration of buck‐boost filter inductor and the transformer magnetizing inductance. In addition, the LCC network provides zero voltage switching (ZVS) operation of the main switches and zero current switching (ZCS) operation of the rectifier diodes over a wide variation of duty cycle operation. Also, load‐independent output current characteristic with improved efficiency is obtained at the resonant frequency operation which is well‐suited for LED applications. Other topology variations of the proposed converter generating step‐up and step‐down voltage gains are introduced for applications with different input voltage ranges. To validate the theoretical analysis and LED driver operation, a 50 W laboratory prototype of the proposed LED driver is implemented for the wide input voltage of 18–40 V to deliver 500 mA output current to a string of 1–30 LEDs, which corresponds to an output voltage range of 3.3–100 V. [ABSTRACT FROM AUTHOR]

A novel magnetic coupling resonance wireless power transfer (MCR‐WPT) system, which has constant‐current (CC) and constant‐voltage (CV) output characteristics suiting for batteries charging, is proposed in this paper. The hybrid compensation topology is adopted; in detail, the LCL‐P circuit topology is used in the CC mode, while the LCL‐S topology is used in the CV mode. Since the switchable components are only located at the receiving side of WPT, the switching can be controlled by the receiving side based on the batteries' state without data communication between transmitting side and receiving side. Furthermore, an adjustable frequency tuning method which is based on proportion integration (PI) closed‐loop controlled by the transmitting side is applied to maximize the current of the transmitting coil. This method also can solve the frequency splitting problem, improving the stability and power of the system while the distance of the two sides changes. The performance of the proposed WPT system is verified by simulation and experiments. The experiment results show that the load current variation is less than 3% in the CC mode and the load voltage changes less than 5% in the CV mode, as the load resister changes from 5 to 20 Ω. [ABSTRACT FROM AUTHOR]

This paper presents a fully soft switched high step‐up DC–DC converter based on quasi‐Z‐source converter. The voltage gain is boosted by combining coupled inductors and switched capacitor techniques. Moreover, a ZVT cell comprising of only a single switch and an inductor coupled to the quasi‐Z‐source inductor is utilized to reduce the magnetic cores and realize soft switching for all semiconductors without imposing any extra voltage or current stress on the converter elements. The main switch operates at zero voltage switching and zero current switching (ZCS) at turn‐on which is independent of the load and duty cycle variations. Hence, soft switching condition for the main switch at turn‐off is easily provided by a snubber capacitor. In addition, the reverse recovery problem of all the converter diodes is significantly mitigated by ZCS at turn‐off while the continuous current at the input source is maintained. In order to verify the theoretical analysis and the proposed converter operation, a converter prototype is implemented at 300 W and 100 kHz. Finally, a comprehensive comparison is performed between the proposed converter and other high step‐up converters based on quasi‐Z‐source structure, to demonstrate the merits of the proposed converter. [ABSTRACT FROM AUTHOR]

An ultra‐low quiescent current tri‐mode DC–DC boost converter is proposed in this paper, which can efficiently handle loads from 1 μA to 300 mA, providing 5‐V output from 3 to 4.2‐V input. Hysteresis current mode control is adopted to realize seamless mode switching between continuous conduction mode (CCM) and discontinuous conduction mode (DCM). In order to deal with the light load situation, this paper proposes a quasi burst mode (QBM). In this mode, most of the modules are turned off and only the QBM controller, low‐power current bias and sample and hold circuit are retained, which significantly reduces the static current of the converter, and thus improves the light load efficiency. Meanwhile, the average current of error amplifier and comparator are reduced significantly by dynamic biasing. Finally, the efficiency of the converter is greatly improved and kept at a reasonable output ripple. The proposed converter is implemented in a 0.13‐μm BCD process design and manufacturing. The test results show that the quiescent current of the converter is only 780 nA, which can achieve a peak efficiency of 95.6%, and ensure that the efficiency is maintained above 80% in the load range of 10 μA to 300 mA. [ABSTRACT FROM AUTHOR]

This paper aims to comprehensively analyze, critically discuss, and provide a step‐by‐step design guideline for a previously proposed Modified Switched‐Inductor type Buck‐Boost (MSIBB) converter which is based on a boost converter. The MSIBB converter is originally based on switched‐inductor phenomena whereby two inductors are switched in a proper sequence to ensure appreciable buck as well as boost characteristics. Appreciable buck and boost characteristics are desirable specifically in low power applications. In regulated low power applications, DC‐DC switching power converters undergo frequent mode‐shift from buck to boost, and vice versa. At the overlap between input/output voltage, the converters efficiency does not suffer significantly, but the wide input‐voltage operating area compels the regulated converters to operate at extreme values of the duty cycle, that is, close to 0 and 1, which causes lower efficiency. A high‐efficiency switching converter is required specifically for low‐power applications that can ensure voltage step‐up and step‐down without resorting to operating at extreme values of the duty‐cycle. In this perspective, switched‐inductors based converter, termed as MSIBB converter, was previously proposed. The MSIBB converter exhibits appreciable voltage‐gain, and experiences lesser current/voltage stress on the semiconductor components. In particular, it has comparable Maximum Switch Stress Factor that generally translates to alleviated switch conduction and switching losses. Besides, the inductors minimum peak stored energy is comparatively lower, reflecting reduced physical size of the inductors as well as reduced onboard losses, and therefore better caters to low power applications. Detailed analysis of the converter and step‐by‐step approach for design example, and comparative analysis are carried out, besides providing some experimental results from the previously proposed converter. [ABSTRACT FROM AUTHOR]

This article suggests a non‐isolated high step‐up interleaved DC–DC topology for renewable energy applications. Two three‐winding coupled‐inductors along with two voltage multiplier cells are used to enhance the voltage gain significantly. One interesting aspect of this new topology is that high duty cycles are not required to achieve high voltage gains; this is done by adjusting the turn ratio of the coupled inductors. Moreover, the presented interleaved converter enjoys not only having less current stress due to the interleaving structure, but also showing 16% increase in voltage gain compared to the best similar boost topologies. Additional elements are designed for the purpose of soft switching and gain increase, which have little effect on the cost, weight and size of the proposed converter. Interestingly, the voltage stresses both on the switching devices and passive elements are much less than the output voltage. Furthermore, the coupled inductor's leakage inductance energy is recovered by employing a passive clamp circuit to minimize stresses across the semiconductors; therefore, efficiency is improved. The suggested converter is analyzed in the steady state, and a 400 W experimental setup was implemented; the outcomes verify the practicality of the proposed boost converter in accordance with the analysis. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate a new strategy for achieving a kind of shape-controlled tunable microwave absorbers based on shape memory polymers (SMPs). Using the heat-driven shape memory effect of SMPs, a frequency-tunable absorber and a magnitude-tunable absorber are designed. Both of the designs consist of a periodic metallic array printed on both sides of the FR4 substrate, SMPs’ substrate (VeroWhitePlus) in the middle layer, and a metallic ground at the bottom. The equivalent circuit models are introduced to analyze the operational principles of the two absorbers. Furthermore, the functionalities of the designed shape-controlled tunable absorbers are investigated by full-wave simulations. For the frequency-tunable absorber design, the simulated results indicate that the resonant frequency can be tuned from 11.3 to 13.5 GHz with a frequency shift of 2.2 GHz. For the other design, the simulated results show that the reflection coefficient can be tuned from −17.00 to −1.34 dB. The proposed frequency shift responses and magnitude modulation responses are experimentally demonstrated by fabricating two prototypes containing 33 $\times33$ units. The above designs overcome the limitation of the traditional electrically adjustable wave absorber requiring an external power supply, providing a new paradigm for the design of tunable devices. [ABSTRACT FROM AUTHOR]

This article is to predict and cancel differential-mode (DM) noise for high-power thyristor (HPT) trigger circuits and improve the reliability of capacitive pulsed power supply (CPPS). A lumped model of HPT trigger circuit is developed for the DM noise prediction within a concerning frequency range. The generation mechanism and propagation path of the DM noise are systematically studied. To attenuate the DM noise, a DM filter is proposed and discussed. The component parameters of the filter are investigated to improve its DM noise suppression effect. The DM spectrum for the HPT trigger circuit and the insertion losses of the DM filter are simulated and analyzed. Ultimately, DM spectrum tests are carried out. Both the simulated and measured results validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article investigates the input–output finite-time stability (IO-FTS) for nonlinear hidden semi-Markov switching systems (S-MSSs) via the asynchronous sliding mode control (SMC) approach. Under the assumption that a detector is set up to estimate the mode value, the mode of the original system is not directly accessible. The asynchrony between the system and controller is described as a hidden semi-Markov model (HSMM). Many practical factors, such as semi-Markov switching parameters, finite-time interval, asynchronous phenomenon, uncertain parameters, and nonlinearity, are taking into account during the SMC design process. We aim to design an efficient finite-time asynchronous SMC scheme under a hidden semi-Markov switching effect. A novel sliding switching surface (SSS) is constructed, in which the SMC law rises asynchronously with original S-MSSs. Then, by means of finite-time stability, an asynchronous SMC law is synthesized to guarantee that the associated hidden S-MSSs fulfill the reaching condition within a finite time. Furthermore, sufficient conditions are derived in view of the IO-FTS of sliding mode dynamics under the framework of a novel inequality lemma. Results are given for the application of this control design method to a single-link robot arm model (SLRAM). [ABSTRACT FROM AUTHOR]

The emerging 4D printing techniques open new horizons for fabricating self-actuated deformable objects by combing strength of 3D printing and stimuli-responsive shape memory materials. This article focuses on designing self-actuated deformable solids for 4D printing such that a solid can be programmed into a temporary shape and later recovers to its original shape after heating. To avoid a high material cost, we choose a dual-material strategy that mixes an expensive thermo-responsive shape memory polymer (SMP) material with a common elastic material, which however leads to undesired deformation at the shape programming stage. We model this shape programming process as two elastic models with different parameters linked by a median shape based on customizing a constitutive model of thermo-responsive SMPs. Taking this material modeling as a foundation, we formulate our design problem as a nonconvex optimization to find the distribution of SMP materials over the whole object as well as the median shape, and develop an efficient and parallelizable method to solve it. We show that our proposed approach is able to design self-actuated deformable objects that cannot be achieved by state of the art approaches, and demonstrate their usefulness with three example applications. [ABSTRACT FROM AUTHOR]

The purpose of web service composition is to satisfy complex requirements by constructing a composite service through loosely coupling web services over the Internet. Services available for composition may experience changes in performance and reliability at any time. Therefore, it is desirable to estimate performance and reliability of the composite service based on the data of atomic services such that it is checked up before service deployment whether the service-level agreement is satisfied. In this article, a phase-type expansion approach to establish an expanded homogeneous continuous time Markov chain of composite web services is proposed. By explicitly including failure states and restart states into the model, both performance and reliability can be computed for the composite service via phase-type fitting method based on the observations on execution times of atomic services. Experimental results based on real-world web services are provided to demonstrate the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

Constrained motion planning is a challenging field of research, aiming for computationally efficient methods that can find a collision-free path on the constraint manifolds between a given start and goal configuration. These planning problems come up surprisingly frequently, such as in robot manipulation for performing daily life assistive tasks. However, few solutions to constrained motion planning are available, and those that exist struggle with high computational time complexity in finding a path solution on the manifolds. To address this challenge, we present Constrained Motion Planning Networks X (CoMPNetX). It is a neural planning approach, comprising a conditional deep neural generator and discriminator with neural gradients-based fast projection operator. We also introduce neural task and scene representations conditioned on which the CoMPNetX generates implicit manifold configurations to turbo-charge any underlying classical planner such as sampling-based motion planning methods for quickly solving complex constrained planning tasks. We show that our method finds path solutions with high success rates and lower computation times than state-of-the-art traditional path-finding tools on various challenging scenarios. [ABSTRACT FROM AUTHOR]

The issue of sliding-mode control (SMC) design is studied for a class of nonlinear semi-Markovian switching systems (S-MSSs) via T–S fuzzy approach. Compared with previous literature, novel integral sliding-mode surfaces (ISMSs) are developed to depend on the designed controller gains and projection matrices. The aim of this work is to design an appropriate fuzzy SMC law under complex stochastic semi-Markovian switching process. For this purpose, the novel ISMSs are developed under the T–S fuzzy modeling framework. Then, based on the weak infinitesimal operator theory, sufficient conditions are given for stochastic stability criteria relying on the sojourn-time. Furthermore, an appropriate fuzzy SMC law is proposed to drive the state signals onto the predefined fuzzy manifold. Finally, an electric circuit model illustrates the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

This article presents an LED driver for lighting and visible light communication (VLC), which utilizes the light of the LEDs to wirelessly transmit data by modulating their instantaneous current. The solution proposed in this article seeks to unite the high efficiency of switched-mode power supplies with the wide bandwidth of linear power amplifiers (LPAs) to achieve high-speed communications. The hybrid converter processes the energy from a 48-V dc bus with an efficiency of 94% while supplying a 20-W LED load, and providing 3.68 MHz of bandwidth for VLC. Details regarding frequency limitations are provided in terms of a Laplace model. The impact of the LPA on the overall efficiency is mitigated by adopting specific design constraints. Finally, experimental results are shown from a prototype working with signals aimed at multicarrier multilevel modulations based on orthogonal frequency division multiplexing. [ABSTRACT FROM AUTHOR]

This article presents a new hybrid-mode pulse-frequency-modulation control method for an LLC resonant converter. In the proposed control method, the primary-side resonant current sensing signal of the current-mode control variable is combined with a ramp signal of the voltage-mode control variable to determine an operating frequency. Then, the proposed control method mainly modulates the ramp signal in accordance with the output load condition. Therefore, the control-to-output voltage transfer function has both the current-mode control and voltage-mode control characteristics that provide fast frequency response and stable output voltage regulation in a light-load condition. In addition, since the ramp signal is also used for slope compensation of the resonant current sensing signal, an external slope compensation circuit is not required. A small-signal ac modeling and loop analysis of the proposed method verify the advantages. The proposed control method is implemented into a field programmable gate array (FPGA) board with an analog front-end board. An experiment is carried out on a 288-W LLC resonant converter. The result shows that the proposed control method provides fast dynamic performance and stable operation under a light-load condition without an additional slope compensation circuit. [ABSTRACT FROM AUTHOR]

Four-dimensional printing (4DP) is a newly emerged technology that uses smart materials for additive manufacturing and thus enables shape and/or property change upon stimulus after the printing process. Present study on 4DP has been focused on open-loop stimulus, which can hardly ensure high shape precision and predictable final states. In this article, a new closed-loop 4DP (CL4DP) process supplementing 4D printed actuation with closed loop control methods is proposed. Image feedback is used for enhancing the conventional open loop 4DP morphing process and a controller is implemented to regulate the intensity of the stimulus accordingly in real-time. To achieve precise control, a nonlinear affine system model is built by model identification with measurement data to describe the dynamic shape recovery process of the 4D-printed shape memory polymer (SMP). Precise shape control is achieved and the effects of controller parameters on the precision of CL4DP are studied. Traditionally, SMP has a discrete number of selected steady states. With CL4DP, such steady states can be continuous and arbitrary. [ABSTRACT FROM AUTHOR]

This article proposes a winding condition monitoring scheme for inverter-fed permanent magnet synchronous machine (PMSM) based on high frequency (HF) current injection. By setting specific current references for the HF positive and negative sequence current regulators, HF current can be injected into different phase winding pairs, and then the HF line voltage deviations are extracted for winding condition monitoring. The amplitude of the extracted HF line voltage deviation is defined as the condition indicator to evaluate the condition of phase winding. In the proposed method, the conditions of all phase windings can be separately monitored, where not only inter-turn short-circuit fault (ISF) in one phase but also ISFs in multiple phases can be accurately identified. Simulations and experiments have been carried out to validate the proposed method. It shows that the proposed method has high sensitivity to ISF and negligible sensitivity to the operation conditions of the PMSM. [ABSTRACT FROM AUTHOR]

A relational bipartite communication problem is presented that has an efficient quantum simultaneous-messages protocol, but no efficient classical two-way protocol. [ABSTRACT FROM AUTHOR]

Power electronic converters are increasingly used in power systems. However, they are vulnerable components and prone to aging failures, thus affecting overall system reliability. Therefore, their availability modeling especially in large-scale power electronic-based power systems is of paramount importance. This letter introduces four different approaches for converter availability modeling considering aging failures under different maintenance strategies. The accuracy and calculation burden of these approaches are illustrated by numerical analysis. It is shown that the method of device of stages and piece-wise approach are the most applicable methods in the case of corrective and preventive maintenance strategies respectively. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive fixed-time convergent continuous controller designed to solve a stock management problem with the objective to drive stock and supply chain levels at the reference values, subject to loss rate disturbances whose bounds are unknown. The only measurable state of the supply chain is the inventory retailer stock level, whereas the supply line inventory level should be estimated. The designed controller includes a fixed-time convergent differentiator, an adaptive fixed-time convergent disturbance observer, and a fixed-time convergent regulator. The adaptive fixed-time convergent observer is used to estimate a disturbance without excessively increasing the controller gains. The controller design is validated in a case study of stock management. The calculated upper estimate for the total settling (convergence) time and the obtained simulation results confirm the fixed-time convergence and the robustness of the designed controller. [ABSTRACT FROM AUTHOR]

Multiple players are each given one independent sample, about which they can only provide limited information to a central referee. Each player is allowed to describe its observed sample to the referee using a channel from a family of channels $\mathcal {W}$ , which can be instantiated to capture, among others, both the communication- and privacy-constrained settings. The referee uses the players’ messages to solve an inference problem on the unknown distribution that generated the samples. We derive lower bounds for the sample complexity of learning and testing discrete distributions in this information-constrained setting. Underlying our bounds is a characterization of the contraction in chi-square distance between the observed distributions of the samples when information constraints are placed. This contraction is captured in a local neighborhood in terms of chi-square and decoupled chi-square fluctuations of a given channel, two quantities we introduce. The former captures the average distance between distributions of channel output for two product distributions on the input, and the latter for a product distribution and a mixture of product distribution on the input. Our bounds are tight for both public- and private-coin protocols. Interestingly, the sample complexity of testing is order-wise higher when restricted to private-coin protocols. [ABSTRACT FROM AUTHOR]

A central server needs to perform statistical inference based on samples that are distributed over multiple users who can each send a message of limited length to the center. We study problems of distribution learning and identity testing in this distributed inference setting and examine the role of shared randomness as a resource. We propose a general-purpose simulate-and-infer strategy that uses only private-coin communication protocols and is sample-optimal for distribution learning. This general strategy turns out to be sample-optimal even for distribution testing among private-coin protocols. Interestingly, we propose a public-coin protocol that outperforms simulate-and-infer for distribution testing and is, in fact, sample-optimal. Underlying our public-coin protocol is a random hash that when applied to the samples minimally contracts the chi-squared distance of their distribution to the uniform distribution. [ABSTRACT FROM AUTHOR]

This study describes a technique for automated and accurate inductance estimation in synchronous DC–DC buck and boost converters. The method of inductor value estimation is based on the dependence of the steady-state output voltage on the inductance value, in the case of a fixed inductor peak current. The measurement algorithm yields effective inductance value, and is aimed to be executed once during the start-up procedure under light load current condition. As the measurement is performed during the start-up sequence with low-load current, a dedicated current sensor with high accuracy can be employed, allowing to target high measurement accuracy in the range of ±5%. The presented technique is developed to enable the automated design of a digital controller for general purpose DC–DC converter but can be used in different applications such as analogue feedback-loop adjustment or improving the digital current estimator accuracy. [ABSTRACT FROM AUTHOR]

On the basis of serious electromagnetic interference (EMI) produced by power electronic equipment, parasitic capacitance existing between transistor and heat sink is considered as the main factor disturbing common-mode loop. Calculation model of parasitic capacitance is established by using finite element method and electrostatic field principle, and computing method is also derived. EMI improvement method for converter system is proposed by controlling the parasitic capacitance impedance. Experimental results show that changing the permittivity and thickness of the thermal conductive adhesive which are filled between the transistor heat-conducting plate and heat sink to can reduce the conducted interference. [ABSTRACT FROM AUTHOR]

The measurement of modal impedances of switching-mode power supplies (SMPSs) is of paramount importance in electromagnetic compatibility applications, especially when designing electromagnetic interference filters to suppress the conducted and radiated electromagnetic emissions is the target. A novel measurement technique that makes use of an impedance analyzer and a coupling transformer and allows extracting the complex value of common- and differential-mode noise source impedance of an SMPS is proposed. The measurement procedure is first studied from the theoretical point of view, then experimentally validated with passive components, and eventually implemented in a CISPR-25 conducted emission test setup to measure the magnitude and phase of modal impedances of an automotive SMPS under different operation conditions. [ABSTRACT FROM AUTHOR]

The symmetrical monopolar configuration is the prevailing scheme configuration for high voltage direct current (HVDC) interconnectors utilizing the modular multilevel converter (MMC) topology. However, the rigid bipolar configuration is gaining significance, as first projects are currently in planning stage. The purpose of this paper is to analyse both HVDC scheme configurations with regard to cable voltage stresses originating from short-circuit faults. The study focuses on HVDC cables with extruded insulation connected to MMCs equipped with half-bridge (HB) submodules. Basic design aspects in rigid bipolar configuration such as the station grounding concept are discussed. Moreover, various station internal as well as dc faults are examined by means of electromagnetic transient (EMT) simulations. Occurring cable voltage stresses are analyzed with respect to voltage polarity, peak value and wave front-parameters and compared in symmetrical monopolar and rigid bipolar configuration. It is demonstrated that cable overvoltages with same polarity as the dc operating voltage are significantly reduced in schemes operating in rigid bipolar configuration. Voltage reversals caused by the discharge process during a cable fault are nearly independent of the selected scheme configuration. Obtained results are relevant with regard to upcoming projects in rigid bipolar configuration and provide insights to further refine insulation co-ordination aspects related to dc cable systems. [ABSTRACT FROM AUTHOR]

This letter presents a multi-objective probabilistic model for the optimal selection of pilot buses in secondary voltage regulation (SVR) of transmission grids. The pilot-bus selection (PS) problem is formulated in the form of a stochastic multi-objective optimization problem (SMOP). The resultant SMOP is solved toward the non-dominated sorting genetic algorithm (NSGA-II) together with a fuzzy set theory. The applicability of the proposed PS model is examined on a classical test system as well as a practical transmission grid. [ABSTRACT FROM AUTHOR]

Microgrid islanding can improve the reliability of distribution networks by enabling load to be supplied even after a fault has occured nearby. The generation and load devices in microgrids are commonly interfaced by power electronics, causing a lack of inertia in the network. When microgrids transition from grid-connected to islanded operation after a fault, fast dynamics occur which have to be evaluated to assess stability during and after the transition. Their stability can be evaluated by time-domain simulations, however detailed and validated models of power electronic loads and distributed energy resources are required. This paper proposes component-based models of different types of power electronic loads, and single and three phase distributed energy resources. The models are validated with a variety of voltage and frequency transient experiments. A case study is performed where a modified version of the Cigre European LV residential network is islanded after a fault occurs. The results of the proposed, constant impedance and exponential load models are compared. The results indicate that the proposed models should be used for accurate analysis of the voltage and frequency stability during microgrid islanding simulations. [ABSTRACT FROM AUTHOR]

In order to understand how geometric errors propagate and how deviations accumulate in a six-axis motion platform (SMP), a new geometric error model based on the stream of variation (SOV) theory is presented in this paper. SOV theory is widely used in industrial engineering with several steps or phases. The conventional geometric error model only calculates the initial and final orientation, yet the deviations after each step in the whole process are still unknown, which are critical parameters in measuring the product quality. In this new error modeling method, each step in the alignment and welding process in SMP can be considered as a station. Thus, the deviations can also be derived after each station, which is beneficial for error identification. Based on the new error modeling approach involving SOV theory, the validation of an optimized configuration is developed by a series of calculations results. By observing the deviations after each station, the optimized configuration can improve accuracy and reduce power loss compared to a traditional configuration. The new error modeling approach based on SOV theory is systematic and comprehensive, and can be applied in other similar environments. [ABSTRACT FROM AUTHOR]

A current-mode buck regulator with delay-based hysteretic control for microcontroller applications is proposed. Unlike conventional hysteretic buck regulators with accurate explicit hysteretic bands, the proposed design relies only on the inherent delay of a low-speed single-threshold comparator to realize the hysteretic band, and can be seamlessly used across all loads in continuous conduction mode and discontinuous conduction mode without modifying the controller's parameters. Moreover, without additional adaptation circuits or frequency regulation loops, the proposed delay-based hysteretic operation does not increase variations in the switching frequency with process and temperature, and results in even less variations in the switching frequency with the input and output voltages when compared to corresponding designs with accurate explicit hysteretic bands. The simplicity of the design reduces silicon area and quiescent current significantly, which in turns enables achieving high efficiency at both heavy and light load conditions as strictly required by low-power microcontrollers. The regulator is designed in a 65 nm digital CMOS technology. It occupies 0.18 mm2 and supports a wide range of input voltages (1.8–4.2 V), output voltages (0.9–1.5 V), and load current (up to 300 mA). Measurement results show that the proposed regulator achieves 95% peak efficiency, while achieving between 62% and 87% efficiency at 10-μA load across all operating conditions. [ABSTRACT FROM AUTHOR]

This paper introduces a novel modeling approach that allows to obtain fast simulations of pulsewidth-modulated dc–dc switched-mode power supplies (SMPS). The proposed methodology combines the use of precise switched models during transient evolutions and averaged models during steady-state or slowly varying conditions. In that way, the resulting mixed modeling approach enables to obtain the detailed switching behavior of SMPS in the context of long-term simulations. The commutation between models is automatically performed in runtime by an algorithm that detects the transient or slowly varying condition according to the evolution of some model variables. When the precise switched model is used, the mentioned algorithm also adjusts the averaged model parameters so that its results are accurate irrespective of the operating point. This paper also describes the implementation of the methodology in the Modelica language and reports simulation experiments showing that the results are as accurate as those obtained using precise switched models, but several times faster. [ABSTRACT FROM AUTHOR]

This paper addresses two problems in the context of two-party communication complexity of functions. First, it concludes the line of research which can be viewed as demonstrating qualitative advantage of quantum communication in the three most common communication “layouts”: two-way interactive communication, one-way communication and simultaneous message passing (SMP). I demonstrate a functional problem $ { \widetilde {cEq}_{T}}$ , whose communication complexity is $O\left ({(\log n)^{2}}\right)$ in the quantum version of the SMP and $\tilde \Omega \left ({ \sqrt {n}}\right)$ in the classical (randomized) version of SMP. Second, this paper contributes to understanding the power of the weakest commonly studied regime of quantum communication–SMP with quantum messages and without shared randomness (the latter restriction can be viewed as a somewhat artificial way of making the quantum model “as weak as possible”). Our function $ { \widetilde {cEq}_{T}}$ has an efficient solution in this regime as well, which means that even lacking shared randomness, quantum SMP can be exponentially stronger than its classical counterpart with shared randomness. [ABSTRACT FROM AUTHOR]

In this paper, a systematic and analytical study of non-isolated topologies belonging to the family of reduced redundant power processing (R2P2) converters is presented. Based on this study, all the non-isolated R2P2 topologies that can be implemented in reality are derived. Detailed examples clarify all possible cases of this analysis. In addition to this, the voltage ratio and the efficiency for each one of the R2P2 configurations are calculated, being further illustrated with examples. A comparison among configurations is also discussed with criteria the high step-up voltage gain and efficiency, aiming for high-power applications. One of these R2P2 converters is selected for further examination, as the most suitable for such applications. The theoretical analysis, as well as the calculations of the step-up voltage ratio and efficiency of the selected converter, is compared to experimental results conducted on a 2-kW laboratory prototype designed to operate in various step-up voltage ratios and in a high-power range, proving the effectiveness of the proposed investigation. [ABSTRACT FROM AUTHOR]

Here, the setup of a three-phase 100 A linear amplifier is proposed. This work focusses on the use of this linear amplifier as power element for machine-emulation. In contrast to common power electronics, a linear amplifier avoids ripple content in the output current caused by switched-mode operation. [ABSTRACT FROM AUTHOR]

This paper describes a method for estimating model parameters $\varepsilon _{s}$ and $\Delta \varepsilon = \varepsilon _{s} - \varepsilon _{\infty }$ from the peaks in the imaginary permittivity and loss-tangent spectra. The analysis describes how measured parameters obtained from an impedance spectrometer, the magnitude of the impedance, and phase angle, are directly converted into complex permittivity and loss tangent. As an application, the method is used to detect and quantify the crystallization of skim-milk powder, which shows a dramatic change in the Debye parameters as it converts from the amorphous to crystalline state. [ABSTRACT FROM AUTHOR]

Summary: This paper analyses current‐fed (current source) isolated dc‐dc converters that are proposed for various renewable energy and dc microgrid applications, such as photovoltaic, fuel cell, or energy storage systems. The analysis addresses current‐fed (boost) full‐bridge converters that achieve clamping and soft switching without dedicated external auxiliary circuits, such as snubbers or clamps. Such converters have certain limitations that can lead to degraded performance and feasibility due to high circulating energy or low silicone utilization at some operating points. The current study reveals these limitations, highlighting advantages and drawbacks of selected snubberless converters at different operating conditions. The relation between the rms input current and the isolation transformer primary current as well as the cumulative rms current of primary semiconductors is used as figure of merit for converter characterization. This approach can be extended and applied to other topology types and used as a universal tool for performance assessment of snubberless converters without auxiliary circuits for particular operating conditions in various systems. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of $\mathscr {L}_\infty$ control for positive delay systems with semi-Markov process. The system is subjected to a semi-Markov process that is time-varying, dependent on the sojourn time, and related to Weibull distribution. The main motivation for this paper is that the practical systems such as the communication network model (CNM) described by positive semi-Markov jump systems (S-MJSs) always need to consider the sudden change in the operating process. To deal with the corresponding problem, some criteria about stochastic stability and $\mathscr {L}_\infty$ boundedness are presented for the open-loop positive S-MJSs. Further, some necessary and sufficient conditions for state-feedback controller satisfying $\mathscr {L}_\infty$ boundedness and positivity of the resulting closed-loop system is established in standard linear programming. Finally, the practical system about the CNM is given to verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Recent studies have proved that sustainable saturation operation of Ferrite Power Inductors (FPIs) allows reducing the inductor size and increasing the power density in Switch-Mode Power Supply (SMPS) applications. This paper discusses a new behavioral model for reliable prediction of ac power loss in FPIs, including the effects of saturation. The new model has been identified by means of the Genetic Programming (GP) algorithm combined with a Multi-Objective Optimization (MOO) technique, starting from large sets of power loss experimental measurements. The proposed ac power loss model uses as input variables the voltage and switching frequency imposed to the inductor by the SMPS operation, while the dc inductor current is used as a parameter expressing the impact of saturation. Such quantities can be easily determined for whatever converter topology and in real-world switching operation, thus confirming the readiness and the easiness-to-use of the proposed behavioral model. The results of experimental tests presented in this paper prove the reliability of the power loss predictions, also by correctly accounting for the impact of inductors saturation. [ABSTRACT FROM AUTHOR]

In many applications, including integer-forcing linear multiple-input and multiple-output (MIMO) receiver design, one needs to solve a successive minima problem (SMP) on an $n$ -dimensional lattice to get an optimal integer coefficient matrix $\boldsymbol {A}^\star \in {Z}^{n\times n}$. In this paper, we first propose an efficient optimal SMP algorithm with an ${\mathcal {O}}(n^{2})$ memory complexity. The main idea behind the new algorithm is it first initializes with a suitable suboptimal solution, which is then updated via a novel algorithm with only ${\mathcal {O}}(n^{2})$ flops in each updating, until $\boldsymbol {A}^{\star }$ is obtained. Different from existing algorithms which find $\boldsymbol {A}^\star $ column by column through using a sphere decoding search strategy $n$ times, the new algorithm uses a search strategy once only. We then rigorously prove the optimality of the proposed algorithm. Furthermore, we theoretically analyze its complexity. In particular, we not only show that the new algorithm is $\Omega (n)$ times faster than the most efficient existing algorithm with polynomial memory complexity, but also assert that it is even more efficient than the most efficient existing algorithm with exponential memory complexity. Finally, numerical simulations are presented to illustrate the optimality and efficiency of our novel SMP algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we propose a sparse signal estimation algorithm that is suitable for many wireless communication systems, especially for the future millimeter wave and underwater communication systems. This algorithm is not only asymptotically optimal, but also robust to the distribution of nonzero entries of the sparse signal. Then, we derive its upper bound and lower bound, and show that the mean square error of the proposed algorithm can approach the minimum mean square error bound when the signal noise ratio goes to infinite or zero. Numerical simulations verify our theoretical analysis and also show that the proposed algorithm converges faster than existing algorithms, e.g., turbo-type signal recovery-discrete fourier transform, approximate message passing, etc. [ABSTRACT FROM AUTHOR]

In mobile platforms, RF interference issues caused by the switched-mode power supply (SMPS) ringing noise often arise in the on-the-go mode and the charging mode of the interface power management integrated circuits. In this paper, we introduce the modeling method for the SMPS ringing noise in the conventional two-level dc–dc converters and then, based on the modeling insight from the two-level dc–dc converter, we investigate and validate the modeling of the SMPS ringing noise in the three-level buck converters, which are newly adopted SMPSs for fast charging in mobile devices. To reduce such noise, we propose the novel SMPS noise-managing methodologies that handle the printed-circuit-board-level design optimization in mobile devices. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new capacitor degradation evaluation method aimed at failure prediction and suitable for digitally controlled switching mode power supply (SMPS) for servers. Electrolytic capacitors have one of the highest component failure rates in SMPS; therefore, we attempt to detect an equivalent series resistance degradation of the electrolytic capacitor directly from the data fetched to a digital controller of the SMPS. With a SPICE simulation and a rapid control prototyping evaluation, we confirm the degradation can be detected by the data at a transient response under a normal operation without additional circuits. Even only 10% of a load step change, which commonly occurs in SMPS for servers, causes detectable transient response degradation. [ABSTRACT FROM PUBLISHER]

This paper analyses the impact of operating modes and nonideal power supply conditions on the efficiency of modern low-voltage power electronic devices. The sophisticated circuits and controls implemented in such devices are expected to result in increased efficiencies, higher operating power factors, and reduced harmonic emissions. However, the interactions of individual PE devices with the supplying network will impact exchanges of powers at fundamental system frequency and nonfundamental (i.e., harmonic) frequencies. This paper correlates the obtained results for harmonic performance and efficiencies over the entire range of operating powers of the considered PE devices using both standard definitions and some alternative interpretations. [ABSTRACT FROM PUBLISHER]

The dc-to-dc boost converter is a singleswitch, single-inductor, switching circuit used to efficiently transform energy from one dc voltage level to a greater voltage level of the same relative polarity. For a specific resistive load range, as the duty cycle decreases, the boost converter inductor enters a discontinuous current mode of operation - the output load current having decreased to a definable level. This paper analyses the fact that a further reduction of load current, as the duty cycle decreases towards zero, will always result in the re-emergence of a continuous inductor current condition. Further, at the other load extreme, high-current, progressively for increasing load current, starting at low duty cycle conditions, the minimum inductor current always increases from a fixed normalised current level, for a specific load range. These and other hitherto unexplored boost converter properties are analysed and verified mathematically and with PSpice simulations. [ABSTRACT FROM AUTHOR]