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Lengthened ion pathway in porous carbon cathode, especially under high mass loading and packing state, severely impeded the ion transport, thus leading to a far unsatisfactory energy/power out of Zn//C capacitors. Here, we report a novel kapok-derived quasi-2D thin-walled porous carbon tile (CT) with proper curvature and rich doping used as stacked bricks. Together with high conductivity single-walled carbon nanotubes, a porous yet relatively packed self-standing carbon cathode was constructed, which features a hierarchical ion path including short ion pathways inside thin-walled porous CTs and adequate channels "highways" caused by rational sub-micron interlayer spacing, thus leading to an excellent combination of rate and gravimetric/volumetric/areal performance at practical mass loading (12 mg cm−2). [Display omitted] • A porous thin-walled layered carbon tile with proper curvature was prepared as bricks. • Porous yet packed cathode feathers hierarchical paths for fast ion/charge transfer. • High rate and gravimetric/volumetric capacity remain in high loading cathode. • The areal capacity increases linearly with the mass loading of cathode. Long ion pathway inside large-sized carbon particle or stacked 2D assembly greatly limit the electrochemical performance of practical carbon cathode (>10 mg cm−2) in Zn//C capacitors. Highly porous activated carbon and holy graphene can alleviate such ion-transport issue, but usually suffer from a far lower packing density and severe restacking, respectively. Herein, a kapok-derived quasi-2D thin-walled microporous carbon tile (CT) with optimized curvature and rich doping was developed and used as bricks. Assisted with single-walled carbon nanotubes (SWNTs), a porous yet relatively packed paper cathode was constructed. The unique doped thin wall (∼700 nm) can effectively shorten the ion-penetration pathways from electrolyte deep into pore structure inside CTs, and thus enlarge ion-accessible surface areas. Combined with rational sub-micron interlayer spacing among proper-curved CTs and bridged-like SWNTs, the continuous ion/charge transport "highways" are fabricated. As a result, such self-standing carbon cathode delivers outstanding rate and gravimetric/areal performance (114 mAh g−1/1.37 mAh cm−2) without sacrificing volumetric capacity even at high mass loading (12 mg cm−2). [ABSTRACT FROM AUTHOR]

To effectively improve the power density and rate capability of layered double hydroxide (LDH) based supercapacitors, a hybrid supercapacitor (HSC) comprising of hierarchical ultrathin NiAl-LDH nanosheet arrays on carbon nanotube paper (CNP-LDH) is developed with porous graphene nanosheets as the negative electrode for the first time. SEM image shows that hierarchical NiAl LDH nanosheet arrays are assembled by numerous ultrathin nanosheets with thickness of a few to tens of nanometers. Remarkably, with an operating voltage of 1.6 V, the HSC possesses a high energy density of 50.0 Wh kg −1 at an average power density of 467 W kg −1 . Even at a fast discharging time of 3.9 s, a high energy density (23.3 Wh kg −1 ) could also be retained at a power density of 21.5 kW kg −1 . Moreover, the HSC exhibits cycling stability with a retention rate of 78% after 5000-cycle charge-discharge test at 5 A g −1 . The results inspire us to propose our high-performance CNP-LDH as a promising electrode for energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aramid-based energy storage capacitor was synthesized by a convenient method. • Electrical breakdown strength was optimized by the interface engineering. • Good dielectric constant thermal stability from RT to 300 °C was achieved. • Our finds promoted the energy storage capacitors in commercial use. Polymer-based dielectric energy storage capacitors show more potential than conventional rigidity ceramic-based capacitors. Recent studies were classified into two categories: the excellent room temperature performance in poly (vinylidene fluoride) (PVDF) systems and the enhanced thermal stability in polyimide-based systems. Only now, however, both of them are still far from commercial use because of their inferior heat resistance or poor processability. By adding BaTiO 3 (BT) particles in maturely used aramid nanofibers, we synthesized the aramid nanofiber (ANF)/BT-based flexible paper capacitors through a convenient industrialized technology in this work. Due to the intrinsic laminated structure of ANF and the uniform distribution of BT particles, the composite film with BT addition of 8 vol% exhibits outstanding dielectric thermal stability. With the help of the interfacial resistance in the organic–inorganic interface, which protected the ANF matrix from being breakdown too early by optimizing the electrical field distribution, a high and stable energy storage density of 6.70 J/cm3 was obtained in ANF/BT5. In addition, excellent energy storage frequency stability with ultrafast discharge speed was also achieved. This work offered a highly repeatable way to synthesize commercially used flexible capacitors, bridging the lab investigation and commercial use in high-power density energy storage polymers. [ABSTRACT FROM AUTHOR]

In this study, the multifunctionality of structural dielectric capacitor made by integrating graphene oxide paper into carbon fibre reinforced composite has been investigated. The study is based on an earlier work on the use of graphene oxide for dielectric material in the structural dielectric capacitor, in which electrical properties have been characterized. In this work, an in-depth study on electrical and mechanical properties of this kind of structural dielectric capacitor have been carried out. In addition, the multifunctional efficiency of structural dielectric capacitors were evaluated and compared with existing structural dielectric capacitors. Through experiments, it is revealed that both electrical and mechanical properties of the structural dielectric capacitors were significantly enhanced by interleaving a graphene oxide paper in the middle of composite. Therefore, the multifunctional efficiency of this kind of structural dielectric capacitors has been ultimately improved, indicating the excellent potential of graphene oxide paper in the development of multifunctional materials for energy storage, potentially for high-strength required applications, such as electric vehicles and unmanned aerial vehicles. [ABSTRACT FROM AUTHOR]

The identification and quantification of chemicals play a vital role in evaluation and surveillance of environmental health and safety. However, current techniques usually depend on costly equipment, professional staff, and/or essential infrastructure, limiting their accessibility. In this work, we develop paper-based capacitive sensors (PCSs) that allow simple, rapid identification and quantification of various chemicals from microliter size samples with the aid of a handheld multimeter. PCSs are low-cost parallel-plate capacitors (~$0.01 per sensor) assembled from layers of aluminum foil and filter paper via double-sided tape. The developed PCSs can identify different kinds of fluids ( e.g. , organic chemicals) and quantify diverse concentrations of substances ( e.g. , heavy metal ions) based on differences in dielectric properties, including capacitance, frequency spectrum, and dielectric loss tangent. The PCS-based method enables chemical identification and quantification to take place much cheaply, simply, and quickly at the point-of-care (POC), holding great promise for environmental monitoring in resource-limited settings. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a flexible and freestanding carbon nanofiber/graphene nanosheet (CNF/GNS) composite paper is prepared via electrospinning followed by high-temperature annealing using a polyacrylonitrile/GNS/dimethylformamide mixture as electrospun precursor. The structure characterizations show that GNS homogeneously distributes in the CNF, forming a thin, light-weight and flexible composite paper. Due to the reinforcing effects coming from CNF and GNS, the Brunauer Emmett Teller (BET) specific surface area, conductivity and capacitance performance of pure CNF are significantly improved after adding GNS. The GNS/CNF composite paper exhibits the largest specific capacitance of 197Fg−1, about 24% higher than that of pure CNF paper. Therefore, based on the above investigations, such GNS/CNF composite paper can be a potential candidate for high-performance flexible capacitors. [Copyright &y& Elsevier]

In order to improve the efficiency of ruthenium dioxide, RuO2, as an electrochemical capacitor electrode, a RuO2 thin film is deposited on carbon paper and its structure and properties are evaluated. This new composite material is prepared via solution dip-coating of a Ru-ethoxide precursor and heat conversion. The coating thickness is easily controlled by varying the number of repetitions of the preparation process. The resulting structure consists of a by homogeneously coated RuO2 film on carbon paper which has a porous graphite matrix. Extensive electrochemical studies have been performed in 1 M H2SO4 electrolyte in order to evaluate the properties of the composite as an electrode in an electrochemical capacitor. The composite material shows not only high specific capacitance (620 F g−1) but also good power characteristics. [Copyright &y& Elsevier]

This paper describes a new vacuum thermal recycling (VTR) method for treating discarded polychlorinated biphenyls (PCB)-contaminated capacitors and pressure-sensitive paper. Based on results demonstrating an exceptionally high PCB separation efficiency and recovery ratio from capacitors containing high-concentration PCBs, i.e. > 99.9%, respectively, the presented VTR method is verified to effectively remove PCBs. In addition, associated safety aspects of the employed procedure were confirmed. [Copyright &y& Elsevier]

Abstract: A nanostructured Ni(OH)2 electrode was prepared and evaluated in supercapacitor application. Mesoporous Ni(OH)2 tubes were integrated onto carbon fiber paper without the use of a binder. The large surface area and porous structure of Ni(OH)2 combined with the effective diffusion of electrolytes through carbon network resulted in an excellent charge storage capacity and good long-term cyclability. [Copyright &y& Elsevier]

Abstract: The requirements and development of high-k dielectric films for application in storage cells of future generation flash and Dynamic Random Access Memory (DRAM) devices are reviewed. Dielectrics with k-value in the 9–30 range are studied as insulators between charge storage layers and control gates in flash devices. For this application, large band gaps (>6eV) and band offsets are required, as well as low trap densities. Materials studied include aluminates and scandates. For DRAM metal–insulator–metal (MIM) capacitors, aggressive scaling of the equivalent oxide thickness (with targets down to 0.3nm) drives the research towards dielectrics with k-values >50. Due to the high aspect ratio of MIMCap structures, highly conformal deposition techniques are needed, triggering a substantial effort to develop Atomic Layer Deposition (ALD) processes for the deposition of metal gates and high-k dielectrics. Materials studied include Sr- and Ba-based perovskites, with SrTiO3 as one of the most promising candidates, as well as tantalates, titanates and niobates. [Copyright &y& Elsevier]

Abstract: We review our recent studies of the passivation of the GaAs and InGaAs surface using a combination of in situ and ex situ surface analysis and capacitor measurements. We find that the control of Ga-oxides in particular appears to play an important role in understanding the characteristics of III–V MOS devices. [Copyright &y& Elsevier]

Abstract: Atomic layer deposited (ALD) HfO2/GeO x N y /Ge(100) and Al2O3/In0.53Ga0.47As(100)−4×2 gate stacks were analyzed both by MOS capacitor electrical characterization and by advanced physical characterization to correlate the presence of electrically-active defects with chemical bonding across the insulator/channel interface. By controlled in situ plasma nitridation of Ge and post-ALD annealing, the capacitance-derived equivalent oxide thickness was reduced to 1.3nm for 5nm HfO2 layers, and mid-gap density of interface states, D it =3×1011 cm−2 eV−1, was obtained. In contrast to the Ge case, where an engineered interface layer greatly improves electrical characteristics, we show that ALD-Al2O3 deposited on the In0.53Ga0.47As (100)−4×2 surface after in situ thermal desorption in the ALD chamber of a protective As cap results in an atomically-abrupt and unpinned interface. By avoiding subcutaneous oxidation of the InGaAs channel during Al2O3 deposition, a relatively passive gate oxide/III–V interface is formed. [Copyright &y& Elsevier]

Abstract: In this paper, a current-mode (CM) Kerwin–Huelsman–Newcomb (KHN) biquad is proposed. The circuit employs three differential-voltage current conveyors (DVCCs) as active elements together with two capacitors and four resistors as passive elements, which all are grounded. The circuit simultaneously provides the three basic filter functions, namely bandpass (BP), highpass (HP) and lowpass (LP) functions. The notch and allpass (AP) functions can be obtained by connecting appropriate output currents directly without using additional active elements. The output signals are obtained at high output impedance ports, which is important for easy cascading in CM operation. SPICE simulation results are given to verify the theoretical analyses. [Copyright &y& Elsevier]

Multilevel inverters produce waveforms that lead to better power quality. Switched-capacitor inverters are one kind that is capable of generating boosted voltage and encourages a single-stage grid-tied inverter solution. In this paper, a four-times boost nine-level inverter with fewer switches is presented in standalone and grid-connected mode. Two switched capacitors, along with eleven switches and one diode, are employed to generate the required boosted nine-level output. The circuit modulation allows self-charging of the capacitors, with the first capacitor charging to the DC source and the second charges to twice of it by shunting it with the combination of the first capacitor voltage and the DC source. This inverter's application can be as a solar PV microinverter due to its fewer components and small filter requirement. The topology is compared with the single-source nine-level inverters and exhibits the lowest cost of all quadruple boost inverters. The presented inverter operation is verified in Simulink and validated on the laboratory prototype. Further, to minimize the leakage current, the circuit is modified accordingly and tested in a hardware-in-the-loop environment. [ABSTRACT FROM AUTHOR]

With the increasing demand for high energy density and reliable dielectric capacitors in the field of power electronics, the research and manufacture of ceramic capacitor materials face significant challenges. At present, the traditional design ideas of dielectric ceramic materials have gradually formalized, and the system is complex and similar, whether it can design dielectric ceramic materials with high performance from a new viewpoint and explore the underlying mechanism remains a great challenge. This paper is based on ceramic capacitors with high energy storage performance, a series of high-entropy perovskite oxide ceramics designed by the concept of "entropy engineering" in the past five years are reviewed. The relationship between microstructure and macroscopic energy storage performance of materials is discussed based on the four effects of high-entropy ceramics. We predict that "entropy engineering" will be a successful strategy to break through the bottleneck of dielectric materials with high energy storage performance. This review guides the custom design of composition-structure-properties in high-entropy energy storage ceramics. [ABSTRACT FROM AUTHOR]

This paper proposed a dynamic current-enhancement technique based on AC coupling network and feedforward compensation capacitor for current-feedback low-dropout regulators (LDOs). Compared with traditional reported current-feedback LDOs, this design exhibits wider input voltage range, greater load capacity and fast transient response, yet no extra power consumption is introduced. Moreover, a complete stability analysis under full load range is given in this paper. The proposed LDO is fabricated in SMIC 0. 18 μ m CMOS process. The input voltage range is 0.8–2.2 V and the maximum load current is 50 mA. The experiment results indicate that the overshoot and undershoot are 76 mV and 141 mV respectively when the load current is varied from 0 to 50 mA within 300 ns under the load of 100 pF load capacitor. • This paper proposed a dynamic current-enhancement technique for current-feedback lowdropout regulators. It significantly reduces the overshoot and undershoot and improves large signal transient response. More importantly, it is not implemented at the expense of more quiescent current. [ABSTRACT FROM AUTHOR]

• In this paper, the loss and thermal stress distribution among SMs of MMC have been investigated which under different capacitance. The relationship between the degree of capacitance degradation and the junction temperature difference among SMs is revealed. • The switching principle of thermal balancing control is studied by analyzing the trend of junction temperature changes in power semiconductor devices. • A thermal balancing method is proposed, offering advantages such as reducing the demand for temperature sensors and eliminating the reliance on high-precision capacitance monitoring technology. The proposed method can effectively achieve balanced junction temperatures of power semiconductor devices among different SMs under capacitor deterioration. Thermal control of semiconductor devices in the submodules (SMs) is a key factor for the safe and reliable operation of modular multilevel converters (MMCs). During normal operation, significant thermal differences can arise among SMs due to the manufacturing tolerance and aging effect of capacitors, which can affect the lifespan of semiconductor devices and even lead to equipment failure. To address the problem, this paper presents a method for achieving thermal balancing among SMs with different capacitances by adjusting their switching principle. Firstly, the relationship between the degree of capacitance degradation and the junction temperature difference among SMs is revealed. Then, by setting data windows to capture the dynamic losses of power devices, which can reflect the trend of junction temperature. The switching principle of thermal balance among SMs is studied based on the trend of junction temperature in power devices. The thermal balancing method has advantages including not requiring high-precision temperature sensors and eliminating the reliance on capacitance monitoring technology. Finally, the simulation and experimentation results demonstrate that the proposed method can effectively achieve balanced junction temperatures of power devices among different SMs. [ABSTRACT FROM AUTHOR]

The integration of renewable energy sources in Medium-/High-voltage DC grids has called up continuous research to develop DC-DC conversion systems. This paper presents a hybrid modular multilevel DC-DC converter topology which successfully overcomes the issue of capacitors voltage imbalance during DC-DC conversion. In the proposed topology, single MMC leg is employed with half-bridge submodules in the upper arm and full-bridge submodules in the lower arm along with soft-switched high-voltage valves. The proposed hybrid modular multilevel converter has inherited arm energy equalization with the help of the parallel connectivity of involved arms' capacitors. During the equalization period, the series-connected upper arm capacitors are connected in parallel to the series-connected lower arm capacitors to transfer the energy between the involved arms which results in operating with balanced capacitors voltages. The proposed modular DC-DC converter is a bidirectional converter which allows power flow from high-voltage side to low-voltage side and vice versa, i.e., it can be operated successfully as a DC transformer. The operational concept of the proposed configuration, control strategy, and parameters design are presented. Simulation results are presented along with experimental results of a scaled-down prototype to validate the proposed approach. Simulation and experimental results show the viability of the suggested approach. [ABSTRACT FROM AUTHOR]

• Split DC link balancing problem is discussed. • Dynamics of partial DC link voltages is derived. • Factors forcing DC link imbalance are analyzed. • Expression for optimal modulating signals zero-sequence component is obtained. Three-phase three-level AC/DC and DC/AC converters have demonstrated several advantages over their classical two-level counterparts such as better efficiency, enhanced total harmonic distortion, lower dv/dt and lesser overall chip area. T-type and neutral point clamped (NPC) topologies dominate the family of three-phase three-level converters, widely used in 10kVA – 100kVA power range. However, control of three-level converters is more complicated than of their classical two-level counterparts due to necessity of adopting an additional voltage loop, aimed to balance partial split DC link voltages. Moreover, the latter contain multiples of triple-base-frequency harmonic ripple even under balanced AC-side operation (this does not happen in two-level converters), which should be minimized by the balancing loop mentioned above. The nature of partial DC link ripple formation was analyzed in-depth for unity power factor operation, yet hardly extended to non-unity power factor cases. Moreover, inaccurate conclusions were drawn in some of the related studies. Consequently, this paper focuses on comprehensive modeling and formulation of split DC link capacitors balancing problem in three-phase three-level bidirectional AC/DC converters operating with arbitrary power factor. Analytical expression for dynamics of partial DC link voltages difference is derived and studied in depth. The relation between zero-sequence component of modulation signals and neutral point current, tending to unbalance partial DC link voltages is explicitly established for arbitrary power factor values. Practical cases of restricted and unrestricted zero-sequence component of modulation signals are presented. Analytical predictions are shown to be fully supported by simulations based on both switching-cycle-averaged and full switched converter models. Experimental results obtained employing a 10kVA T-type converter prototype operating with restricted zero-sequence component of modulation signals under different power factor values are also given to further validate the presented methodology. [ABSTRACT FROM AUTHOR]

Abstract Flexible graphite sheets or graphite paper are conductive substrates produced in large scale for use in a wide range of applications, such as in telecommunications, lighting, computer and peripherals, power conversion, and heat generating semiconductors (low-cost material). In this paper we show, for the first time, that commercially available graphite sheets can be used in the as-received condition for the construction of disposable electrodes with excellent performance for electroanalysis (comparable to glassy carbon). Nine different graphite sheets were evaluated by different techniques, such as scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, square wave voltammetry, and amperometry. The obtained results revealed the existence of large variations between different commercially available materials (not all the sheets work well as sensors in the as-received condition). Our studies have shown that there are commercial flexible graphite sheets with higher electrical conductivity and superior homogeneous composition, which are ideal for use as disposable unmodified or modified sensors. The quality of the results obtained with graphite sheets are dependent on the type of material selected as substrate. However, repetitive results are obtained if the same material is always used. The graphite sheets were coupled to low cost 3D-printed cells forming easy to use disposable devices. The performance of the disposable devices was evaluated using ferri-ferrocyanide and ferrocene probes, dopamine (LOD = 0.7 μmol L−1), catechol (LOD = 0.8 μmol L−1), ciprofloxacin (LOD = 5.9 μmol L−1), cadmium (LOD = 0.013 μmol L−1), and lead (LOD = 0.07 μmol L−1) as model analytes. According to our knowledge, the electroanalytical performance of graphite sheets demonstrated here surpasses previously reported results. Graphical abstract Unlabelled Image Highlights • Robust and disposable conductive substrates for production of electrochemical devices. • Sensor performance is highly dependent on the type of industrial graphite paper selected as a carbon substrate. • Large-area graphite films for construction of modified disposable sensors • Graphite paper and 3D-printed cells: a robust and cost-effective assembly [ABSTRACT FROM AUTHOR]

This paper proposes a capacitor-free Flipped Voltage Follower (FVF) Low Dropout (LDO) regulator. To stabilize the feed-back loop, the proposed multi-stage FVF LDO regulator does not require a Miller compensation capacitor or physical resistor. A capacitor-free internal structure improves closed-loop bandwidth while saving area in the LDO regulator. In this work, a large feed-forward transconductor (g m f) is proposed, which generates a strong left-half-plane (LHP) zero while consuming a small bias current. The large feed-forward transconductor boosts the LDO regulator's DC gain and bandwidth. The proposed FVF LDO regulator is implemented in standard 130 nm CMOS technology and achieves a unity gain frequency of more than 35 MHz while consuming a total quiescent current of 97 μ A. The proposed FVF LDO regulator has an active area of 0. 0054 mm 2 , which is less than many other LDO regulators that have been reported. • The proposed LDO does not require any compensation capacitors. • The active area of the proposed LDO is small as compared to other reported LDOs. • The large feed-forward transconductor is realized with less bias current. • The proposed LDO uses efficient SRE, which helps LDO settle faster. • The proposed LDO settles faster, with settling time of 130 ns. [ABSTRACT FROM AUTHOR]

Supercapacitors, also known as ultracapacitors or Electric Double-Layer Capacitors, are considered as new solutions for space power supplies because of their advantages such as a high power-density, a wide temperature range and a long life. Graphene supercapacitors (GSCs), with graphene structure served as the highly active material, are new types of high-performance and new-concept supercapacitors. However, there are no cases of supercapacitors, especially GSCs, being used as power system for spacecraft independently. This paper introduces the design, test and application of the power supply based on GSCs for the electromagnetic separation system in Q-SAT mission. The power supply is integrated by multiple GSCs to meet the requirements of the separation system, providing 600W power within 2 × 10−5 m3 and 1 kg. The design, packaging method, test and result is reported in the paper. The rated voltage of the selected GSCs is 2.7 V, and the power density reaches 1.1 × 103 W/kg and 2.6 × 106 W/m3. The power supply based on GSCs has passed the verification test successfully including mechanical, electrical, vacuum and thermal tests from −20–60 °C. It successfully drove the separation system and guaranteed the task of unlocking and releasing Q-SAT in the flight on Aug 6, 2020. The significance of this work lies in the following aspects: First, the feasibility of application on the satellite separation system in space of GSC is demonstrated. Second, the design and application case of supercapacitor as a driving power supply for a satellite separation system is presented. Third, a screening and integration method for GSCs packaged as a space power supply is proposed and verified. The space power supply based on GSCs will be used more widely in space according to this research. • A new power supply based on graphene supercapacitors (GSCs) is developed and designed for the satellite separation system. • A screening and integration method for GSC integrated as high-power space power supply is proposed and practiced. • The power supply based on GSCs is applied and verified in the Q-SAT mission. • The application in space of supercapacitors is pushed forward by the research. [ABSTRACT FROM AUTHOR]

Inside the oil-paper insulation of high voltage condenser-type bushings and instrument transformers, conducting surfaces or capacitive shields have been in use for many years to control electric field distribution. Traditional insulation design methods take into consideration dielectric stresses in axial and radial directions, but experience shows that partial discharges occur in the vicinity of capacitive shield edges and can severely affect the expected life of oil-paper insulation. In this paper, a criterion for dimensioning condenser-type insulation systems is presented, based on maximum electric field at sharp edge of capacitive shield. Maximum permitted value of the electric field at the shield’s edge was obtained through numerous experimental tests and numerical field calculations based on the finite element method (FEM). [ABSTRACT FROM AUTHOR]

Delta-configured Cascaded H-Bridge (DCHB) topology is a suitable alternative for Static Synchronous Compensator (STATCOM) applications. However, under unbalanced voltage and/or current conditions, zero-sequence current needs to be injected to guarantee dc-link capacitor voltage balancing. The control loop of this zero-sequence current is analyzed in this paper, in order to determine the requirements that the implemented controller must fulfill. Considering these requirements, appropriate transient response and stability margin indicators are defined to quantify and evaluate the performance of different controllers that could be employed —Proportional-Resonant controller (PR), PR controller with delay compensation (PR d), and Vector Proportional-Integral controller (VPI) are proposed and analyzed for this application in this paper. Based on the defined indicators, the VPI is the most appropriate among the studied control techniques. Experimental results validate the analytical model of the controllers and their performance. • Identification of the particularities of the i 0 control loop in a DCHB STATCOM. • Definition of appropriate indicators to quantify the performance of the controllers. • Comparison of the PR, PR d and VPI controllers. • VPI preferable option to the PR and PR d in the scenario under study. • Experimental validation in a 100 kVA set-up. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 T x flakes are modified by alkalization and post-annealing treatments. • Most of –F and –OH functional groups in the Ti 3 C 2 T x can be removed. • The modified Ti 3 C 2 T x is combined with nanocellulose extracted from soybean stalks. • The composite film exhibits high tensile strength and large electrical conductivity. • Great performance is achieved for both supercapacitors and zinc ion capacitors. Ti 3 C 2 T x is a promising electrode material for supercapacitors, whereas it suffers from the re-stacking problem and fluorine-rich functional groups, thereby restricting its electrochemical performance. Herein, delaminated Ti 3 C 2 T x flakes are modified by alkalization and post-annealing treatments to considerably decrease –F and –OH functional groups. In addition, inspired by the architecture of nacres, the modified Ti 3 C 2 T x is combined with soybean stalk-derived nanofibrillated cellulose, which can improve mechanical properties, prevent dense packing of Ti 3 C 2 T x , and facilitate the transport of electrolyte ions. Therefore, the optimized composite film exhibits large tensile strength (53.9 MPa), high electrical conductivity (24930 S m−1), and superior electrochemical performance for supercapacitors and zinc-ion capacitors. In particular, the composite film under quasi-solid-state supercapacitor configuration delivers high capacitances of 303.1 and 211.4 F g−1 at 1 and 10 mA cm−2, respectively, excellent cyclability (92.84% capacitance retention over 10,000 cycles), and great affordability to bending deformations. This work offers an efficient way to construct high-performance flexible electrodes for high-power applications. [ABSTRACT FROM AUTHOR]

Multilevel inverters have been widely used in various applications, as they provide output voltage with better quality, lower d v /d t , and lower Total Harmonic Distortion (THD). Multilevel inverter such as Neutral Point Clamped (NPC) inverter uses a large number of semiconductor devices (IGBTs and diodes) which negatively affects the inverter cost and efficiency. Recently, a three-level (3L) F-type inverter has been proposed with lower switch voltage stresses, cost, and losses compared to 3L T-type and NPC inverters. This paper proposes a five-level (5L) F-type inverter as an extension for the 3L F-type inverter. Like a 5L NPC inverter, the voltages of the involved dc-link capacitors should be kept at a certain voltage level. To achieve that, buck-boost converter-based Equalization Channels (ECs) are employed. To show the pros and cons of the 5L F-type inverter, a comparison between the proposed inverter and other existing multilevel inverters has been held. The numerical assessment also shows that the proposed architecture has a lower kVA rating and losses than the conventional 5L NPC inverter. Finally, different Simulation and experimental results of the proposed 5L F-type inverter are presented. The presented results show the viability of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper presents a simple realization of the meminductor emulator using two operational transconductance amplifiers (OTAs) and two capacitors. To obtain different configurations of meminductor in the proposed design, one of the OTA has been replaced by a multi-output transconductance amplifier (MO-OTA). MO-OTA is a slightly modified version of conventional OTA that has multiple outputs. The design flexibilities offered by MO-OTA helped in achieving decremental as well as incremental configurations for both grounded and floating meminductor emulators. The proposed meminductor emulator realizations are very simple because these emulators do not employ an analog multiplier, resistor, or memristor. The pinched hysteresis curves have been acquired for the frequency range of 600 kHz–900 kHz for different values of capacitors. The proposed meminductor emulators have been designed and simulated with the help of the LTspice tool using TSMC 180 nm CMOS technology parameters. The pinched hysteresis loops, transient analysis, and non-volatility tests of the proposed meminductor emulators confirm their satisfactory behavior as meminductor. The functioning of proposed meminductor emulator circuits has also been tested by demonstrating their use in chaotic oscillators. • A very simple circuitry for grounded and floating meminductor emulators requiring only two OTAs and two capacitors. • Flexibility of switching between incremental and decremental meminductor emulators for both grounded and floating types. • Avoids the requirement of memristor, multiplier, and resistor in the realization. • Significant range of operating frequency. • Demonstration of chaotic responses obtained by Chua's oscillator using proposed meminductor emulator. [ABSTRACT FROM AUTHOR]

• A new state observer (SO) based capacitor-voltage-balancing method for MMC is proposed. • The design procedure and the performance of the SO based method are presented and analyzed. • The proposed method is validated on a real laboratory prototype. This paper proposes a state observer (SO) based capacitor-voltage-balancing method for modular multilevel converters (MMCs) without arm-current sensors. Without the knowledge of the actual arm-current signals, this method can balance capacitor voltages while reducing the sampling signals, compacting the control system and saving the overall cost. In this paper, the arm-current value estimated by an SO, instead of the measured one, is employed to determine which sub-modules (SMs) should be inserted or bypassed. Furthermore, the design procedure of the proposed SO is presented. In addition, a medium voltage MMC (20 kV, 25 MW) simulation model using Matlab/Simulink is constructed to verify the proposed method. Finally, the proposed method is also validated by experimental results based on a scaled-down MMC prototype. [ABSTRACT FROM AUTHOR]

Li-ion batteries exhibit high energy density, while supercapacitors demonstrate high power density and long cycle life. A series of unimpeachable studies show that adding capacitive carbon to cathodes can construct a new type of capacitor batteries to greatly improve the rate capability and cycle life of Li-ion batteries without significantly reducing the energy density, so as to realize the technology integration of capacitor and battery. In this paper, with the aim of preparing high performance cathode material for capacitor battery, the cathode material with high speed electron, ion channels and high specific power and capacity is constructed by controlling the surface functional group of carbon additives, particle size and the characteristics of ion electron transport. The results show that although the presence of oxygen-containing functional groups on the surface of capacitive carbon can improve the capacity of capacitive carbon itself, it has adverse effects on the rate capability of cathode material of Li-ion batteries, and the more the oxygen content, the greater the internal resistance of the hybrid electrode, and the worse the electrochemical stability of the electrolyte. The size matching between the capacitive carbon particles and the cathode material can not only ensure good electron close contact and vibration density, but also the appropriate size of carbon additives can alleviate the volume expansion of the cathode electrode to enhance the cycle stability. Hybrid cathode electrodes constructed by LiNi 0.6 Co 0.2 Mn 0.2 O 2 and capacitive carbon with different oxygen-containing functional groups were prepared. By reasonably regulating the functional groups of capacitive carbon additives, high-rate performance is achieved while reducing system resistance and suppressing gas production to realize safe and efficient service of the battery. Moreover, we proposes a principle criterion of what size carbon additive should be selected for the particle size of cathode material. This paper can provide a theoretical guidance for building a capacitive lithium-ion battery with good rate capabilty and long endurability, especially under a high current charge/discharge. [Display omitted] [ABSTRACT FROM AUTHOR]

Capacitor allocation is one of the most important topics in distribution network operation. In this paper, reactive power based on capacitors allocation is presented in electrical distribution network using mathematical Remora Optimization Algorithm (ROA) as a powerful optimization method to identify the optimal location and size of the capacitors in the networks. The objective function is defined as minimizing the cost of losses, purchasing and installation costs, as well as the cost of capacitors operation at different loading conditions. Problem optimization variables include the optimal site and size of the capacitors in the network, which is found considering the objective function, operating conditions and reactive size of the capacitors using the ROA. The method based on the ROA is studied on IEEE 33 and 69 buses networks. The simulations are evaluated in different scenarios including capacitors allocation with and without PLNLI as well as in different loading. The simulation results are indicated the capability of the proposed methodology in comparison with previous studies in losses reduction, voltage profile enhancement, reducing annual costs and increasing net saving. The results are also showed that considering PLNLI offers fewer losses, better voltage profiles and of course higher annual cost than the conditions without considering it. In addition, the results clear that reducing the electrical network load level causes reduction of losses cost, voltage fluctuations and also the annual cost of the network. So, optimal implementation of the capacitor allocation based on the ROA in the electrical network can be able to improve the characteristics of the network and also increase the net saving by optimally injecting the reactive power. [ABSTRACT FROM AUTHOR]

This paper presents a 16-bit 1-Msps successive-approximation-register analog-to-digital converter (ADC) with a split-ADC digital calibration scheme based on dynamic element matching. A multi-segment capacitor array with redundant bits is utilised for ensuring that missing-level errors are calibrated in the digital domain, reducing the area and power consumption. The key circuit modules are optimised, such as the low-power dual-mode cascade comparator and dynamic element matching control logic. The prototype is fabricated by a 0.18-μm CMOS technology, and it exhibits 170.47 dB figure of merit Schreier (FoMs), 15.04 bits effective number of bits (ENOB) and 119.50 dB spurs free dynamic range (SFDR). The peak differential nonlinearity (DNL) and integral nonlinearity (INL) are −0.422/0.536 LSB and −0.721/0.758 LSB, respectively. • A 16-bit 1 Msps SAR ADC is manufactured in 0.18 μm CMOS process with 170.47 dB FoMs. • A split-ADC digital calibration scheme based on dynamic element matching can improve the SFDR effectively. • A segmented capacitor array of 4 sub-capacitor arrays decreases the total capacitance of the high-resolution SAR ADC. • A dual-mode automatic zero comparator is utilised to reduce power consumption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vertically aligned reduced graphene oxide arrays are obtained via laser assistance. • The redox-active tannic acid is introduced which plays multiple roles in this work. • This unique design provides abundant adsorption sites and transfer channels. • The multiple charge storage mechanisms of V-rGO/TA/LGP cathode are investigated. • The optimized cathode shows good electrochemical performance for Zn2+ ion storage. Aqueous zinc-ion hybrid capacitors (AZHCs) are considered an encouraging energy storage candidate owing to their promising environmental benignity and electrochemical performance. To give full play to the advantages of AZHCs, vertically aligned reduced graphene oxide/tannic acid (V-rGO/TA) arrays are constructed on the laser-pretreated graphite paper (LGP) as flexible carbon-based cathodes (V-rGO/TA/LGP) for AZHCs by a facile laser reduction method. The vertical structure of rGO exhibits abundant physical adsorption sites and ion/electron transfer channels, and the residual oxygen-containing groups of rGO provide favored chemical adsorption sites, which can enhance Zn2+ ion storage. In addition, the TA molecules contribute extra capacity by reversible redox reaction (phenol-quinone transition), further improving the electrochemical performance of the electrode. Consequently, the assembled quasi-solid-state AZHC based on the optimized V-rGO/TA/LGP cathode possesses a high specific capacity of 136.6 µAh cm−2 and a maximum energy density of 109.3 μWh cm−2. In addition, the device exhibits good flexibility with a capacity retention of 97.0 % even after 3000 bending cycles. This design strategy opens up a new approach to construct a vertically aligned carbon material for achieving high-performance flexible AZHCs and realizing their practical applications. [ABSTRACT FROM AUTHOR]

• The faulty operation of MMC with hot-reserved SMs is analyzed. • NLM corrector based fault-tolerant strategy for high-voltage MMC is proposed. • The strategy features simplicity, low voltage stress and little influence scope. The reliable and consistent operations of modular multilevel converters (MMCs) under fault conditions are crucial for high-voltage and high-power applications. To strengthen the performances of MMCs under submodule (SM) faults, a fault- tolerant strategy based on the nearest level modulation (NLM) is proposed in this paper. According to the changed AC component in the faulty arm voltage, this method adds a corrector in NLM, which remedies the faulty arm voltage by adjusting the number of inserted SMs for the faulty arm. Then, the faulty operation can be recovered to the normal. The corrector is simple to realize and can effectively suppress the odd-order circulating currents. Under the proposed method, only the ripples of the capacitor voltages in the faulty arm rise. The average voltage stress on each capacitor is the same as that in normal operation since the rated capacitor voltage in the faulty arm has no rise. No measure and influence impose on healthy arms. With features of simplicity, low voltage stress and little influence scope, the proposed strategy is fit for high-voltage MMCs. The feasibility of the proposed strategy is verified by the simulation results with the professional tool Matlab/Simulink. [ABSTRACT FROM AUTHOR]

SiC power MOSFETs are reported to suffer from both positive and negative threshold voltage shifts. Positive shift is well understood in the literature and attributed to electron trapping in near interface oxide traps (NIOTs). Negative shift is explained by hole generation and trapping in the oxide via impact ionization favored by the strong oxide field. However, studies on negative shift are still ongoing, and the origin and nature of the process are not fully understood. This study advances the comprehension of negative threshold voltage shift by investigating MOS capacitors subject to positive bias stress. We demonstrate that: a) a significant negative threshold shift is observed when the electric field is greater than 7.5 MV/cm; b) the detected shift is not recoverable at zero bias. Recovery can be obtained only by applying a positive gate voltage indicating a field-driven detrapping process. c) Trap-state mapping measurements were carried out to extract the activation energy of the detrapping processes, and a weak thermal activation was observed. Results collected within this paper indicate that holes are trapped at deep centers, and thermal detrapping is not possible. Hole release is only possible when a high field is applied to the insulator, possibly due to the recombination between leaking electrons and trapped holes. [ABSTRACT FROM AUTHOR]

A symmetrical multilevel dc-dc boost converter with ripple reduction structure for solar PV Systems is analyzed in this paper. The converter is structured by differentially connecting two multilevel boost converters. The advantages of the topology are: high voltage gain, low switch stress and the ability to reduce the input-current ripple and the voltage ripple on the capacitors. The reduction of the capacitors ripple reduces the size requirement for the capacitors when it operates in a complimentary switching manner. A detailed analysis of the converter in the continuous conduction-mode, boundary conduction-mode, power processing, design requirements, nonideality of the converter are discussed. The experimental results of the laboratory prototype of the converter are verified. [ABSTRACT FROM AUTHOR]

• A novel technique to determine the capacitance for capacitor-run single phase motor has been proposed. • Measurement of current in both main winding and auxiliary winding, has been performed. • A novel technique to measure the roundness of flux trajectory has been proposed using roundness algorithm. This research paper presents a novel technique to determine the required value of capacitor used in a capacitor-run single phase induction motor. Dynamic analysis of main winding and auxiliary winding currents are performed and the electromagnetic flux revolving in the stator-rotor air gap is studied. In capacitor-run single phase induction motors, the most suitable capacitor is one that produces an electromagnetic flux that has a uniform trajectory (distribution) along the air gap. The novel technique presented in this research paper is the application of roundness algorithm to determine the most uniform trajectory of electromagnetic flux produced by varying auxiliary winding capacitors. The value of capacitance thus found from the proposed technique is compared with the motor manufacturer recommended capacitance. The agreement of the comparison validates the usefulness of the proposed technique. [ABSTRACT FROM AUTHOR]

Most electronic products experience several stages in their life-cycle, including introduction, growth, maturity, decline, phase-out, and obsolescence. With the accelerated growth of the electronics industry, new materials, processes and components are being introduced at an increasing speed which adds to the complexity of the life cycle stages of electronic products. This paper presents the life cycle process and provides three examples to demonstrate how electronics materials, processes and components have life cycle changes. The paper then discusses the problems induced by rapid changes, including the need for re-qualification. Then methods to address the problems are presented, including lifetime buys, acquisition from the aftermarkets, uprating commercial components, and products re-design. [ABSTRACT FROM AUTHOR]

Highlights • This paper proposes two controlling methods for SVC in smart grid with connected EV charger. • SMC, ASRFC with a HVC are separately applied in the grid. • This paper presents usage of proposed methods for decreasing size of capacitor and value of apparent power loss. • The proposed scheme is validated through computer simulations of a 22.9-kV grid. Abstract Electric Vehicles (EVs) play a pivotal role in reducing the emissions of greenhouse gases in the world. Currently demand for EVs has abruptly increased for transportation and other applications. Using more EVs causes an increasing load on the power system. Random EV charging yields voltage distortion, which results in an unbalanced grid. In a distributed system, the connection of EVs to the grid may diminish the power factor, which increases the apparent power loss. The Static VAR Compensator (SVC), which is a FACTS device, is applied to the power system to compensate the voltage distortions and apparent power loss. In this paper, two controlling methods are contemplated and tested in a SVC to reduce the apparent power loss and minimize the capacitor size of the SVC in comparison with the conventional control method in a SVC. Proposed methods are also compared with the conventional control method used for SVC. The Slide Mode Controller (SMC) and Asymmetric Synchronous Reference Frame Controller (ASRFC) with a Harmonic Voltage Compensator (HVC) are separately applied in the grid. This paper presents usage of SMC and ASRFC methods for decreasing size of capacitor and value of apparent power loss through computer simulations of a 22.9-kV grid. With application of new controllers, apparent power loss of grid will be reduced as compared with conventional method of SVC controller. Moreover, the size of SVC capacitor can also be reduced. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Multi-string PV systems provide several advantages over other topologies. • Asymmetric Cascaded H-bridge (ACHB) inverter is attractive for photovoltaic applications. • Regulation of the dc-link capacitor voltages is the most important problem of the ACHB inverter. • This paper proposes a simple and powerful FS-MPC to control an Asymmetric Cascaded H-Bridge Photovoltaic Inverter. Abstract This paper presents a Finite-Set Model Predictive Control (FS-MPC) method adapted for an Asymmetric and Cascaded H-bridge Photovoltaic inverter (ACHB). This advanced control approach is designed to: Ensure an independent Maximum Power Point Tracking (MPPT), Synthesize at the inverter output a sinusoidal multistep PWM waveform, and provide an output current with unity power factor and low harmonic distortion. ACHB seems to be a perfect candidate for Photovoltaic systems. However, the control of such kind of converters is quite a challenging task. On the other hand, FS-MPC has achieved great popularity due to the ease with which the constraints, nonlinearities, and switching actions can be included in the controller formulation. Classical approach to tune the FS-MPC parameters is not fruitful for an ACHB. In this concern, we propose, new and dynamic, parameters for the FS-MPC algorithm. This approach is evaluated under different operating conditions including robustness tests. Results provide that the proposed FS-MPC method features a great flexibility and control potential. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the design and test of a 0.5 MA generator with a tunable pulse shape. The main parts are: the storage capacitor (3.95 μ F ∼ 12.6 kJ at 80 kV), multi-channel coaxial switch, strip transmission line, load, pulse forming block (two versions are considered here, namely with peaking capacitor and wire opening switch). A set of inductances in parallel with the peaking switch as well as using various gases into this switch allow us to modify the current wave shape. Jitter from shot to shot did not exceed 10 ns in the experiments. This paper describes the design of main module elements and the results of experiments for two schemes at operation on load equivalent. In combination of the two pulse forming blocks, the generator proves the possibility of pulse shape tuning in a very wide range, namely delivering between 400 and 600 kA with a 200–800 ns rise time. The generator weight was ∼ 200 kg and the dimensions are 1x0.6x0.8 1 m3 with a pumping system. The generator design allowed for an easy increase in the number of modules in the arbitrary series–parallel combination in order to get the required current amplitude and pulse shape. Operation and handling are very simple, because no oil, water, nor SF6 are required for the generator. [ABSTRACT FROM AUTHOR]

Abstract Metallized film capacitors are used to reduce electromagnetic interference (EMI) in electric power mains due to their high voltage capability and their open circuit failure mode, which aids in safe operation. This paper presents a comprehensive review of metallized film capacitors used for EMI filtering and their failure modes and mechanisms. One of the major failure mechanisms discussed is the corrosion of the metallized film due to moisture ingress into the package. Safety, quality, and reliability standards for metallized film capacitors are also discussed. The paper concludes with recommendations for film capacitor selection and the proper qualification and accelerated life testing to ensure long-term reliable operation. [ABSTRACT FROM AUTHOR]

Abstract In this paper an automated CAD tool that can be used in integrated circuit technology characterization is proposed. The proposed methodology fills the gap found in old, as well as, new IC design methodologies. The tool allows the user to perform a rapid and full characterization for different device models available in a process design kit (PDK). A set of pre-defined suite of test-benches are created to cover different aspects of circuit design. A seamless integration of the tool in typical design environments is achieved using SKILL code and OCEAN script. Moreover, the tool can compare different PDK releases or different technologies in terms of DC/AC performance, high frequency operation, leakage, and layout area efficiency. The paper presents the tool structure, interface, and capabilities. Finally, a characterization example is applied to CMOS 130 nm technology; results are shown for different devices characterization: MOSFET, BJT, Diode, Resistor, and Capacitor. [ABSTRACT FROM AUTHOR]

Recently, hybrid Modular Multilevel Converter (MMC) composed of Half-Bridge Sub-Module (HBSM) and Full-Bridge Sub-Module (FBSM) is becoming a preferable topology in overhead line based HVDC transmission. Assuming that two switches are paralleled in each HBSM and FBSM to double the current ratings, this paper proposes an enhanced hybrid MMC topology based on the improved series–parallel HBSMs and two-port FBSMs. The two types of Sub-Module (SM) segments are obtained from direct mirror flipping of all the traditional SMs, but with more degrees of freedom for control. The proposed topology maintains the dc-fault ride through capability and can minimize the requirements of capacitor voltage sensors and control hardware. Then the nearest level capacitor voltage control strategy suitable for the new topology is proposed and implemented by controlling the specific switches to parallel adjacent capacitors for voltage equalization, and the spike currents during the parallel procedure can be suppressed by the distributed arm inductors, this is defined as capacitor voltage self-balancing in this paper. The effectiveness of this work has been validated in terms of steady and transient states on a two-terminal hybrid MMC based HVDC system. [ABSTRACT FROM AUTHOR]

Highlights • Structural capacitors are multifunctional structural materials. • They provide the capacitor function for the purpose of electrical energy storage. • This paper reviews the scientific development of structural capacitors. • This paper also enunciates the design and applications of structural capacitors. • Structural capacitors will provide an untapped form of energy storage. Abstract Structural capacitors are multifunctional structural materials that provide the capacitor function for the purpose of electrical energy storage. This paper reviews the development of structural capacitors and enunciates their design and applications. A structural capacitor is commonly a polymer-matrix structural composite with a dielectric film between the electrodes, which are an electronic conductor, commonly the continuous carbon fiber laminae that serve to reinforce the composite. The dielectric film is preferably small in thickness and serves to avoid short circuiting of the two electrodes. In order to maximize the capacitance by having the structural capacitor constitute capacitors in parallel, the dielectric film is preferably positioned at every interlaminar interface of the composite, such that alternating electrodes in the stack are connected to opposite polarities of the AC electric field source. A structural supercapacitor requires the matrix to be a solid electrolyte. From the viewpoints of structural performance, safety, service life and high frequency capability, structural dielectric capacitors are closer to commercialization readiness than structural supercapacitors. Structural capacitors have not yet been commercialized, but they are expected to provide an untapped, extensive, save and distributed means of energy storage, and allow aircraft, satellites, automobile, ships, wind turbines, buildings, solar panels, display panels, outdoor lighting, computers, cell phones, etc., to store energy in their structures. [ABSTRACT FROM AUTHOR]

Abstract In this paper, an analytical assessment of non-sinusoidal reactive power of shunt capacitors in the presence of substation voltage harmonics in radial distribution systems has been attempted. The paper proposes a novel technique of assessing harmonic amplification in shunt capacitor banks due to distorted substation voltage. The proposed algorithm is based on the computation of Total Harmonic Distortion (THD) of bus voltages and shunt capacitor currents in which various non-sinusoidal terms are quantified as per IEEE-1459-2010 Standard. The article also highlights the extent of overloading of shunt capacitor banks and propagation of voltage distortion in various downstream buses of the distribution system under investigation. Proposed method is tested on two radial distribution systems and demonstrates good convergence characteristics. [ABSTRACT FROM AUTHOR]

In this paper, a delay-dependent state feedback based supplementary damping controller of Thyristor Controlled Series Capacitor (TCSC) is designed to enhance the damping of inter-area oscillations of an interconnected power system. Although wide-area feedback signals are advantageous for damping enhancement of inter-area modes, but its usage as feedback signals in designing of a damping controller together with physical limitation of the actuator introduces time-delay and actuator saturation in the feedback loop. This results in degradation of the power system performance and even cause instability. The paper focuses on designing a damping controller considering the aforesaid time-delay and actuator saturation effects. Residue approach and Schur balanced truncation model reduction methods are used to obtain input-output control signals and reduced order power system model. The nonlinear effects of the actuator saturation are consider in the closed-loop system by using generalized sector condition. Based on Lyapunov–Krasovskii functional approach, a delay-dependent stability and stabilization conditions via linear matrix inequalities (LMIs) formulation are derived to guarantee the asymptotic stability of the closed-loop system. Then the problem of designing a state feedback control law which maximizes the region of attraction is formulated and solved as an optimization problem with LMI constraints. Simulation studies in the two-area four-machine power system demonstrate the effectiveness of the proposed controller for damping enhancement of the inter-area oscillations and compensating the effect of time-delays and actuator saturation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 1:1 scale laboratory test bench for electric powertrains. • Battery and supercapacitor-based hybrid energy storage systems. • Experimental validation of supercapacitor models. • Novel analytical methods for maximizing the effectiveness of hybrid energy storage systems in real electric powertrains. Abstract This paper deals with hybrid energy storage system (HESS) management strategies, optimized for urban road electric vehicle applications. These new control strategies aim to extend battery pack durability by reducing charging/discharging current peaks by means of supercapacitors. The optimization is carried out with reference to the case study of a HESS composed of a high power unit, i.e. supercapacitor module plus a high energy unit, i.e. a battery pack, based on nickel-chloride ZEBRA (ZEolite Battery Research Africa) technology. On-board integration of the two storage devices is obtained through a DC/DC bidirectional power converter, as this configuration is particularly convenient for many kinds of urban vehicle operations. The novelty of this work consists in an analytical methodology, based on non-linear programming and calculus of variations theory, to evaluate management strategies characterized by high effectiveness in reducing battery current transients. The identification and optimization of these strategies are initially performed on the basis of a vehicle model, built in the Matlab-Simulink simulation environment. To this purpose, the experimental characterization of the supercapacitor module is obtained with reference to three different models, whose selection depends on the required fitting performance and computational effort indexes, as evaluated in the paper. The energy management strategies identified show promising results in the simulation environment, followed by experimental activities carried out by means of a dedicated 1:1 scale laboratory test bench. The various experimental results presented in this manuscript highlight that the identified λ-control strategy presents effectiveness values up to 57%, close to the ideal results obtained in the simulation environment. In fact, the methodology proposed in this paper, validated by laboratory experiments, definitely reduces the negative consequences of power peaks on the HESS, indicating the real possibility of using these results in the design and control of urban road vehicles. [ABSTRACT FROM AUTHOR]

Highlights • We propose the novel overlap dual capacitor structure sensor. • We use the PZT/P(VDF-TrFE) composite material to prepare the overlap dual capacitor structure sensor. • The proposed structure can reduce the radiation area by half; it is conducive to the miniaturization of devices. • We prepare the device by use of the novel overlap dual capacitor structure sensor, the performances have been measured. • The device that is assembled the overlap dual capacitor structure sensor exhibit excellent SNR , detection distance and D*. Abstract The pyroelectric infrared device that uses the overlap dual capacitor structure sensor is reported in this paper. The sensor is prepared by use of the PZT and P(VDF-TrFE) composite material. In order to fabricate the new-device, we use the overlap dual capacitor structure sensor to replace the conventional parallel dual capacitor structure sensor. The overlap dual capacitor structure can reduce the radiation area of the sensor by half; the smaller sensor is more conducive to the miniaturization of the device and the preparation of multiple-sensing device. The signal to noise ratio SNR of the new-device has increased by 15.14% compared with the conventional-device due to the overlap dual capacitor structure sensor. The peak-to-peak value Vpp , broadband-noise Vn , narrowband-noise Vnoise , and detectivity D* of the new-device, which is assembled with the overlap dual capacitor structure sensor, are all measured and calculated in this paper. [ABSTRACT FROM AUTHOR]

This paper is about the control of Modular multilevel converters, an innovative technology in the design of converters, which is beginning to be included in real installations. Papers about this topic include simulation models, circulating current reduction, voltage modulators, capacitor voltage balancing and control issues. The scheme for current source regulation used in this article includes all control loops, which are, from the outermost to innermost, DC bus voltage regulator, current regulator, voltage modulator, capacitor voltage balancing, and a PLL for the synchronization to the grid. Disposition-sinusoidal pulse width modulation is used as the voltage modulator, and an enhanced control strategy in the stationary reference frame for 3-phase MMCs is used for the inner current control loops. Very detailed simulations of the complete control system have been performed for both the enhanced control strategy in the stationary reference frame, and the well-known control in the synchronous reference frame, as well as some experiments using the hardware-in-the-loop simulation technique. The validation of these control strategies is made by a comparison of the capability of each one to compensate the harmonic distortions of the utility grid according to the grid code. The correct operation has been tested in the case of a strong/weak grid, unbalances and grid failures. [ABSTRACT FROM AUTHOR]