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We report microsecond timescale switching between the superconducting and normal states of commercially manufactured high-T c superconducting wires using optical radiation to heat the conductor above T c. The achieved voltages and switching times have significant implications for a new class of thermal switches. The report contains experimental data for photo-induced microsecond scale voltage transients as well as numerical analysis of heat propagation through the material in response to optical radiation. The microbridges are etched into commercially manufactured coated conductors and submerged in liquid nitrogen. By varying the magnitude of the transport current, two different optical responses are identified. At low transport currents, short-lived voltage transients occur, transitioning to persistent latching once the current is increased above a threshold value. The microbridge, therefore, behaves as a fast opening and closing switch when carrying low currents or an optically latched thyristor at high currents. This is understood to occur due to critical current suppression as a result of heating from the optical pulse. Optically induced heating reduces the superconducting volume fraction, and Joule heating due to the transport current interaction with the high temperature superconducting occurs, which either causes short-lived or stable self-heating normal regions dependent on the magnitude of the transport current. This study is concluded with an estimate of the energy necessary to drive the microbridge into the resistive state. The observed behavior can potentially be utilized as a switching element in superconducting transformer rectifiers where high frequency switch operation is required. [ABSTRACT FROM AUTHOR]

In this study, the aim is to evaluate three-phase (3φ) three-level (3L) neutral point clamped AC/DC rectifier for high-power applications. The rectifier analysis has been simulated using a new modified carrier-based level-shifted PWM technique. The 3L-NPC rectifier, which uses the new level-shifted PWM technique, is compared with the classical triangular carrier-based PWM signal. This new PWM technique provides low output voltage ripple, low total harmonic distortion (THD) for input current, unit input power factor, a well-regulated DC bus voltage and capacitor voltage balance for the NPC rectifier which is considered for implementation in high-power applications. This proposed modified carrier-based PWM is highly successful for 3L-NPC rectifier which is rated from 75 to 350 kW power applications. The system simulation results demonstrate the validity and flexibility of the proposed new carrier-based level-shifted PWM method for NPC rectifier in high-power applications. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a Direct Power Control (DPC) based on a virtual flux estimator and an optimal Switching Table (VF-ST-DPC) for a three-phase PWM rectifier. The proposed approach combines DPC principles, a virtual flux estimator concept, and an optimal switching table (ST) to select the optimal converter vector control. The objectives of this approach are to solve the cross-coupling between instantaneous active and reactive powers for each sector and to enhance harmonic line currents. Thus, the proposed method is carried out in a fixed coordinate frame. It therefore does not require a Park transformation or the synchronization of the grid voltage, which is achieved by a virtual flux estimation method. Experimental results, based on the dSpace DS1104 board, show that the VF-ST-DPC ensures smooth and decoupled control of instantaneous active and reactive power, as well as low harmonic levels (THD = 4.6%), verifying the expected performances of the proposed method under both steady-state and transient operations. [ABSTRACT FROM AUTHOR]

In order to improve the control performance and reliability of the pulse-width modulation (PWM) rectifiers in electric vehicle (EV) charging systems, the evaluation of DC bus capacitor health status is critical. In order to accurately monitor the health status of DC bus capacitors, a data-driven model fusion method is developed. In the method, multi-layer perceptron, random forest, and XGBoost are adopted as the base learners that produce separate row predictions. The second-level learner, support vector machine (SVM) accepts the outputs of the previous learners and integrates them into the final health status prediction. Meanwhile, the feature vector is constructed by only collecting the grid voltage, the grid current and the AC component of DC bus voltage. With the feature vector as input, the proposed method is able to accurately predict the health status of DC bus capacitor. Finally, we built a three-phase PWM rectifier as an experimental platform for validation. The experimental results verify that the proposed method fully utilizes the advantages of data-driven and model fusion, and achieves a high accuracy in the health state evaluation of DC bus capacitor. [ABSTRACT FROM AUTHOR]

This study proposes an adaptive high-frequency injection method (AHFI) aimed at mitigating common-mode voltage (CMV) on the AC side and alleviating current stress on power semiconductor devices within each arm of a medium-voltage motor propulsion system designed for modular multilevel converters. By adjusting the quantity of high-frequency components injected into each arm according to the fluctuation coefficient, the amplitude of injected high-frequency CMV and circulating currents can be reduced across medium to rated motor speeds. This approach enhances the start-up performance of medium-voltage motor drives while diminishing CMV effects on the motor side, resulting in decreased total harmonic distortion (THD) in the three-phase output waveforms. Furthermore, the effectiveness of the proposed AHFI method in SM voltage regulation and circulating current control under low-frequency operation is thoroughly analyzed. The validity of this method is established through comprehensive mathematical scrutiny and time–domain simulations performed using MATLAB/SIMULINK software (MATLAB version R2021b), along with real-time simulations conducted employing the real-time simulator OPAL/RT via hardware-in-the-loop simulation (HILS). [ABSTRACT FROM AUTHOR]

In this work, a higher order-to-fundamental mode converter is reported and analyzed based on an asymmetric dual channel waveguide (ADC-WG) on silicon. In the reported structure, one of the two waveguides is infiltrated with nematic liquid crystal (NLC) material to add temperature tunability while the other one is a solid BK7 waveguide. The modal characteristics are obtained using the full vectorial finite difference method (FVFDM). In addition, the structural parameters and optical characteristics of the employed materials are investigated to achieve good wavelength selectivity with a short device length (LD). Thus, a compact mode converter that can work at different wavelengths including the telecommunication wavelength i.e., 1.55 μm with LD ~ 482.31 μm and a low crosstalk of − 19.86 dB is presented. To prove the thermal tunability of the suggested mode converter, its operation is tested through a temperature range between 20 and 35 °C and the results show that the mode conversion process is achieved at each temperature with different phase matching wavelengths (λPMW) but with quite similar coupling length (LC). The proposed device can therefore be effectively utilized in integrated photonic circuits. [ABSTRACT FROM AUTHOR]

The present investigation introduces an advanced methodology for maximum power point tracking (MPPT) applied to a piezo harvester scheme. A comprehensive rectifier circuit, equipped with an embedded MPPT component, is established to optimize energy production by monitoring a DC-DC inverter connected to the rectifier. Furthermore, the system's sensitivity error has been finely tuned to dynamically adjust its impedance unit in real time, thereby optimizing load acquisition. This innovative approach seamlessly integrates the MPPT algorithm into the piezo harvester circuit. Moreover, the vehicle's road handling is significantly augmented through the incorporation of a robust steering front and an active differential control system. Leveraging the MPPT module, the rectifier consistently achieves a power recovery efficiency exceeding 85%, independent of varying load conditions. Additionally, a DC-DC converter circuit has been seamlessly integrated to finely adjust the output voltage to meet specified levels. Numerical simulations demonstrate the effectiveness of the harvesting scheme, extracting a substantial output power of 90 W with an overall efficiency of 70%. The improved MPPT approach, employing angles of arrival (AoA) DV-Hop control strategies, minimizes the system's power consumption based on the Global Positioning System (GPS). The utilization of Harris Hawks optimization (HHO) and the generation of quadrants in the four-quadrant operation mode of DC motors in the wireless sensor network (RCSFs) have been significantly enhanced in this study. Simulations reveal that, at a velocity of 50 km/h, shock absorbers utilizing the received signal strength indication (RSSI) can harvest between 60 and 90 W on a class C road, based on the time of arrival (TOA). Striking a balance in ride comfort using the time difference of arrival (TDOA) as a trade-off constitutes approximately 30% of the piezoelectric harvester (PEH) system's power consumption when operating in active suspension mode, optimized by particle swarm optimization (PSO). [ABSTRACT FROM AUTHOR]

This paper presents a computer-simulation-based design of an in-line, coaxial-to-circular waveguide adapter for converting the coaxial transverse electromagnetic (TEM) mode to the circular waveguide TE11 mode over more than a one-octave bandwidth. The proposed adapter consists of a coaxial-to-rectangular waveguide transformer employing a stepped-ridge converter and a rectangular-to-circular waveguide transformer employing a curved transition. The proposed adapter has been optimized using a commercial simulation tool. The dimensions of the designed adapter are given so that it can be verified by anyone who is interested. The designed adapter operates from 8.00 GHz to 22.95 GHz (2.87:1 bandwidth) with a reflection coefficient of less than −20 dB and a higher-order mode level of less than −25.0 dB. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT) and nonequilibrium Green's function (NEGF) framework, to study the monolayer (ML) blue phosphorene (BlueP) doped with C along zigzag direction, such as the structural stability, and electronic and transport properties. Interestingly, we found that doping engineering strategies can effectively transform monolayer ML ZBlueP doped with C into a spintronic nanodevice with a few unique transport properties. Firstly, our model showed a magnificently giant magnetoresistance (GMR) up to 10 $ ^4 $ 4 under low bias. Secondly, a rectifier with a large rectification ratio (RR) of 10 $ ^5 $ 5 was observed. Lastly, negative differential resistance with a peak-to-valley current ratio (PVCR) of 10 $ ^4 $ 4 was observed. Our research shows a promising route towards the development of high-performance ML ZBlueP spintronics technology by doping with C atom. Our results indicate that our models have immense potential for application in nanoscale spintronic devices. [ABSTRACT FROM AUTHOR]

This paper presents electronically tunable current conveyors using low-voltage, low-power, multiple-input operational transconductance amplifiers (MI-OTAs). The MI-OTA is realized using the multiple-input bulk-driven Metal Oxide Semiconductor transistor (MIBD-MOST) technique to achieve minimum power consumption. The MI-OTA also features high linearity, a wide input range, and a simple Complementary Metal Oxide Semiconductor (CMOS). Thus, high-performance electronically tunable current conveyors are obtained. With the MI-OTA-based current conveyor, both an electronically tunable differential difference current conveyor (EDDCC) and a second-generation electronically tunable current conveyor (ECCII) are available. Unlike the conventional differential difference current conveyor (DDCC) and second-generation current conveyor (CCII), the current gains of the EDDCC and ECCII can be controlled by adjusting the transconductance ratio of the current conveyors. The proposed EDDCC has been used to realize a voltage-to-current converter and current-mode universal filter to show the advantages of the current gain of the EDDCC. The proposed current conveyors and their applications are designed and simulated in the Cadence environment using 0.18 μm TSMC (Taiwan Semiconductor Manufacturing Company) CMOS technology. The proposed circuit uses ±0.5 V of power supply and consumes 90 μW of power. The simulation results are presented and confirm the functionality of the proposed circuit and the filter application. Furthermore, the experimental measurement of the EDDCC implemented in the form of a breadboard connection using a commercially available LM13700 device is presented. [ABSTRACT FROM AUTHOR]

Converter transformer is the key equipment in UHVDC transmission. If a local overheating fault occurs, it will inevitably form a local hot spot on the core, winding or other structural parts. Among these faults, multipoint grounding and interlaminar short circuit faults account for 30–50% of core accidents. The continuous overheating of 150–250 °C will cause ablation on the silicon steel sheet, which will destroy the insulation material and reduce the insulation performance. In severe cases, it will cause thermal expansion, resulting in local deformation or displacement of the core. Considering the scale of size and temperature parameters, the scale model of converter transformer is established based on the principle of constant magnetic flux density. By using the homogenization theory, the scaled model under multipoint grounding and interlaminar short circuit fault is simulated by electromagnetic heat. First, the single-phase four-column model of the core is established according to the scaled principle, and the core is refined. Secondly, taking the refined model as the research object, the magnetic thermal coupling simulation and analysis are carried out under multi-point grounding and interlaminar short circuit fault, and the magnetic density, eddy current loss and temperature distribution on each lamination are obtained. Finally, the correctness of the simulation is verified by the one-dimensional eddy current loss analytical equation, which provides a reference for the local overheating problem of converter transformers. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a new light‐emitting diode (LED) driver based on full‐bridge series resonant converter (SRC) is presented. In the proposed converter LED, load is placed in between DC source and the input side of the full‐bridge inverter which reduces the rectifier components of the SRC. The proposed converter reduces the number of diodes used for rectification and ensures zero voltage switching of the power switches which improves the efficiency of the converter. LED lamp current is regulated with phase‐shift pulse width modulation (PWM) of full‐bridge. Lamp illumination is controlled with PWM dimming. The operation and mathematical analysis of LED driver is presented. To validate the proposed concept, a 40‐W laboratory prototype is developed. Experimental results are presented. Peak efficiency of 93% is obtained. [ABSTRACT FROM AUTHOR]

Summary: This study describes a three‐phase six‐level (TPSL) inverter‐based dynamic voltage restorer (DVR) that employs a newly designed isolated multi‐port interleaved flyback converter (IMPIFC). A conventional DVR needs a big and heavy series transformer even for a three‐phase low‐voltage system, which is rated up to 400 V. Power electronic engineers have developed high‐frequency isolated DC–DC converters as a result of the introduction of advanced semiconductor devices and magnetic cores. Control and performance of a low‐voltage DVR utilizing a high‐frequency isolated DC–DC converter are discussed. In the proposed IMPIFC, the high‐frequency (25 kHz) transformer, which is smaller in size than the line‐frequency transformer, is utilized to reduce the size and to integrate multiple energy sources together. In addition, the introduction of a TPSL inverter into the configuration of DVR considerably reduces the injection of harmonic components into the distribution network. The proposed structure of DVR is named as "TPSL‐DVR." The experimental findings of a three‐phase, three‐wire, 400 V, 50 Hz, 2kW laboratory system validate the boosting ability, feasibility, and efficiency of the system layout. [ABSTRACT FROM AUTHOR]

In this paper, a Dickson-based RF-DC (Radio frequency power to direct current power) rectifier for energy harvesting system is designed. Dickson double-voltage structure, voltage-dividing structure and switching transistors are integrated in the system to fulfil the synchronous rectifying function, which can upgrade PCE (Power Conversion Efficiency) value, reduce the threshold voltage and decrease the leakage current, etc.. The simulation is conducted on the designed synchronous rectifier for energy harvesting of 900 MHz signal. It shows that when the input voltage $${V_{IN}} = 1V$$ V IN = 1 V , the peak output DC voltage can be stabilised at 1.8 V with the assistance of LDO (Low dropout) regulator, while the reverse leakage current is below 20 µA and the PCE value reaches 58%. The designed rectifier is assembled and tested in the paper. Both the simulation and testing results demonstrate the feasibility of the proposed synchronous rectifier. [ABSTRACT FROM AUTHOR]

We report a facile method to prepare an array of liquid-crystal polarization converters (LCPCA) based on hydrophobic microcavity arrays. The reactive ion etching (RIE) technique was chosen to treat the homeotropic polyimide (PI⊥) layers through a metal mask with a through-hole array. Under the selective RIE treatment, a hydrophobic–hydrophilic pattern is obtained due to the increase in surface energy in the etched area from ∼34.6 to ∼73.2 mN/m. The etched area forms a microcavity with a diameter of 520 μm, depth of ∼23 nm, and center distance of 690 μm, which is consistent with the dimensions of the metal mask. Since the walls of the microcavity retain hydrophobicity, the liquid-crystal (LC) molecules show a radial arrangement in the microcavity. Combining a substrate covered by a parallel rubbed homogeneous polyimide (PI∥) layer with the substrate covered by a microcavity-patterned PI⊥ layer can form a "sandwich" structure. The LC molecules in the microcavities are arranged in a twisted-radial texture, which can convert linearly polarized light to radially or azimuthally polarized light depending on the polarization direction of the incident light. The proposed method has the merits of simple steps, controllable size, and easy to fabricate large-area arrays. Our LCPCA has potential applications in tight focus, material processing, biological tissue analysis, particle capture, and optical data storage. [ABSTRACT FROM AUTHOR]

NiO/Ga2O3 heterojunction rectifiers were exposed to 1 Mrad fluences of Co-60 γ-rays either with or without reverse biases. While there is a small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000× reduction in forward current and a 100× increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on–off ratio is also reduced by almost five orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of <4 cm−1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current–voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate that these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes. [ABSTRACT FROM AUTHOR]

In this article, the coupled inductor is designed using a litz wire, an enameled litz wire, and a solid wire separately. All the coupled inductors wound with litz and solid wires are tested in a Cuk converter operated in DCM with a 25 kHz switching frequency for 15 W power, and winding losses of each wire, including proximity and skin effect loss, are calculated analytically without using any software, by using different techniques presented in literature, and the results are compared. Also, state-space modeling of the converter using a coupled inductor for DCM is derived as a contribution of the article because such a modeling is not derived for the Cuk converter in the literature. Thanks to the applications, inductor currents, switch voltage, input–output voltage, and output current are measured for coupled inductors with different wires. In addition, FEM simulation and co-simulation of all coupled inductors are realized, and the results obtained by applications are verified by them. Besides, it is shown that while the number of turns is the same, increasing the bundle of wires increases efficiency and inductance, reducing the window area and coupling coefficient. [ABSTRACT FROM AUTHOR]

Substantial attention has been drawn over the past few years by high step-up dc-dc converters owing to their applications in a wide range. Apart from renewable energy applications, high voltage/ high pulse converters are efficiently used in water treatment applications. The converter suggested a combination of Quadratic and SEPIC converters with a diode-capacitor cell. This topology generates high-voltage repetitive pulses with a single semiconductor switch and reduced component count. The stress across the components is less than the high-gain converters reported in the literature. The topology has an extendable feature by increasing the number of diode-capacitor cells without affecting the stress. The superiority of the high pulse generating topology is validated with a similar converter in the literature. This paper discusses the nL5 simulator results for the proposed rated topology required for water treatment. A scaled-down 50 W prototype is tested for various input voltages to generate high voltage pulse, and the analytical study is validated. [ABSTRACT FROM AUTHOR]

It is impossible to imagine modern electronic circuitry without a p–n junction—an essential building block for transistors, rectifiers, amplifiers, photovoltaics, etc. Conventional fabrication processes (ion implantation or chemical diffusion) result in an immutable potential configuration depriving reconfigurability. In contrast, the superior electrostatic tunability, dangling bonds‐ and reconstruction‐free interfaces are some of the key features of 2D based heterostructures, making them promising candidates for cutting‐edge optoelectronic and memory applications. Herein, the intercoupled 2D ferroelectricity of 훼‐In2Se3 is utilized to introduce micron‐scale, non‐volatile electrostatic doping in ambipolar WSe2, enabling reconfigurable p–n junction. The actuation mechanism is based on the strong polarization field along the edge topology of In2Se3. The fabricated device presents stable p–n to n–p switching, a superior rectification ratio of ≈106, and a low leakage current of ≈10−12 A. Furthermore, the switchable short‐circuit current response is utilized to demonstrate a novel self‐powered, non‐volatile memory based on photovoltaic reading. The ferroelectric non‐volatility coupled with the ability to control the device operation using optical and electrical signals paves the way for ultrathin energy‐efficient, multi‐level optoelectronic and in‐memory logic devices. [ABSTRACT FROM AUTHOR]

Rectenna is the key component in radio-frequency circuits for receiving and converting electromagnetic waves into direct current. However, it is very challenging for the conventional semiconductor diode switches to rectify high-frequency signals for 6G telecommunication (>100 GHz), medical detection (>THz), and rectenna solar cells (optical frequencies). Such a major challenge can be resolved by replacing the conventional semiconductor diodes with tunneling diodes as the rectenna switches. In this work, metal–insulator–metal (MIM) tunneling diodes based on 2D insulating materials were designed, and their performance was evaluated using a comprehensive simulation approach which includes a density-function theory simulation of 2D insulator materials, the modeling of the electrical characteristics of tunneling diodes, and circuit simulation for rectifiers. It is found that novel 2D insulators such as monolayer TiO2 can be obtained by oxidizing sulfur-metal layered materials. The MIM diodes based on such insulators exhibit fast tunneling and excellent current rectifying properties. Such tunneling diodes effectively convert the received high-frequency electromagnetic waves into direct current. [ABSTRACT FROM AUTHOR]

A very simple, compact and low-power second generation voltage conveyor circuit using only eight transistors is proposed in this work. Voltage follower stage is implemented using merged voltage follower (MVF), offering very low output impedance. A simple current mirror forms the input stage of the proposed voltage conveyor. To further enhance the linearity, another circuit is proposed where input transistor in MVF is replaced with DTMOS (Dynamic Threshold Voltage MOSFET), giving ± 1 2 0 mV linearity range as compared to ± 2 0 mV of the first proposal. Proposed-II VCII provides reduced offset voltage due to decreased effective threshold of DTMOS, and gain bandwidth product of the circuit also improves. Simulation results are computed using 180-nmCMOS technology with supply voltage of ± 0. 4 5 V to validate the proposed circuits. Proposed-I and proposed-II VCII consume 85.1 μ W and 97.5 μ W, respectively. An application of the proposed conveyors as "current to voltage converter", is also presented. [ABSTRACT FROM AUTHOR]

Rectifier diodes play a vital role in the operational aspects of a superconducting magnet, and their selection and characterization are crucial for optimal performance and reliability. These diodes are placed within the magnet cryostat, which subjects them to liquid helium (4.2 K) or cryogenic temperatures. The behavior of power diodes can change significantly at cryogenic temperatures. Hence, it is essential to verify their performance before they are installed onto a superconducting magnet system. Thus, a test bench was developed to determine the V–I characteristics of power diodes at low temperatures. In this paper, the two power diodes were tested at 300 K, 77 K, and 4.2 K. The forward voltage was found to increase and have a modest reduction in the on-resistance with the decreases in temperature. The diodes withstood low temperatures down to 4.2 K. The observed forward voltage for the power diode was 4.78 V at 4.2 K, which is around 6–7 times higher than that at room temperature. [ABSTRACT FROM AUTHOR]

Power converters are the key link to realize energy transfer from hybrid energy systems (HESs) to loads. In this paper, a family of boost and buck-boost DC-DC converters that is highly desirable for HESs is proposed and analyzed. The proposed converters possess continuous input currents that can realize small input current ripples and avoid the use of large input filters. Besides, the semiconductor counts of the proposed converters are low. Two of the converters employ single-switch double-diode while the other two adopt single-switch triple-diode. The reduced semiconductor counts greatly improve converter efficiency and system reliability. In addition, these boost and buck-boost converters have high voltage-boosting capabilities, and wide voltage gain ranges can be achieved when they are applied to HESs. Theoretical analyses and an experimental prototype are used to verify the characteristics and effectiveness of these converters. [ABSTRACT FROM AUTHOR]

Power converters can convert the electrical energy output by power source into specific forms required by target device. They are widely used in various fields such as electrification, transportation, and power systems, and are the core components of the systems. Power converters are composed of power semiconductor devices (such as IGBTs), which are prone to failure due to abnormal conditions and aging degradation, leading to power converter faults. Therefore, over the past twenty years, extensive fault diagnosis methods for power converters have been studied and proposed. Among them, symmetry-based methods have the characteristics of rapid diagnosis speed and strong robustness, but so far there's no systemic summary of such methods. Therefore, this paper reviews the relevant research on fault diagnosis of power converters based on symmetry in recent years, analyzes the mathematical principles of these methods, and compares their diagnostic performance. In addition, two factors that may have an influence on the symmetry are pointed out. This paper provides references and suggestions for the future development and research of power converter fault diagnosis. [ABSTRACT FROM AUTHOR]

The temperature distribution of ultrahigh voltage (UHV) converter transformer is the key to its service life, allowable load and safe operation. The influence of a high‐proportion and large‐value harmonic current on the magnetic field, loss and temperature distribution of a UHV converter transformer is studied. A new calculation method is proposed to determine the winding temperature under the combined actions of multiple key factors. First, the skin effect of UHV converter transformer winding under high proportion and high current harmonics is analysed extensively. It is found that the increase of harmonic current frequency leads to exponential increase of winding loss and temperature by changing skin depth. Second, based on the superposition principle, a calculation method for winding loss considering harmonic current and different load rates is developed. The temperature distribution under different harmonic current frequencies and contents is obtained. The winding losses and temperature under different harmonic currents are quantified. Finally, a new calculation method is proposed for the converter transformer winding temperature, considering the combined actions of factors such as load rate, cooling oil inlet rate and temperature, harmonic current frequency and content. Experimental verification showed an error of only 0.58 K in the actual transformer hotspot temperature, confirming the effectiveness of this method. This method is of great significance for temperature control and safe operation of UHV converter transformers. [ABSTRACT FROM AUTHOR]

A stacked polyphase bridge converter consists of multiple standard, three‐phase two‐level voltage source inverters connected in series to the same dc voltage source. The authors present a decentralised and dynamic dc‐bus reconfiguration strategy for this type of converter. The innovation of the proposed strategy lies in its ability to isolate or reactivate one of the inverters in the series connection online, even in motoring mode, enabling increased fault tolerance and an extended speed range. Both the required hardware alterations and the multi‐agent control strategy are addressed. Its major benefits compared to the state‐of‐the‐art are that only two additional active, unidirectional semiconductor switches are required per inverter, and that the control is based on local computations, local measurements and neighbour‐to‐neighbour communication only. Hence, the scalability and reliability of the hardware are extended towards the control. Simulations and experimental results on a 4 kW modular axial‐flux PMSM prove the feasibility of the concept, and validate that the dc‐bus can be reconfigured in 100 ms, without torque interruption. [ABSTRACT FROM AUTHOR]

Summary: An isolated high‐efficiency, high step‐down converter for ultracapacitor charger is presented. The proposed converter utilized the structure of switched inductors and combined the current‐doubler synchronous rectifier, which can reduce the secondary circulating currents. In addition, the energy of the leakage inductance can be recycled to reduce the voltage stresses of the switches. Therefore, the proposed converter can supply the requirement of charging high current, and keep converting high efficiency at the same time. The maximum efficiency of the proposed converter reaches 96.53% at 350 W, and the full load 1 kW is 94.31%, in the case of input voltage 380 V and output voltage 14.6 V. Finally, a 250 F ultracapacitor is charged by the proposed converter from 0 to 14.6 V with constant current (CC) and constant voltage (CV) modes in 1 min. The proposed converters can prove their feasibility by experimental results. [ABSTRACT FROM AUTHOR]

Fuel Cell Hybrid Electric Vehicles (FCHEV) use batteries and Photo Voltaic (PV) arrays to overcome Fuel Cell (FC) limitations like slow reaction times and low power densities. In a traditional power conversion system, three converters link FC, PV array, and battery to the output load. Despite using the FC, PV array, and battery, it has three inductors and several switches. Each switch also endures high voltage stress, possibly lowering power density and efficiency. This paper proposes a single-inductor multi-input converter (SI-MIC) that achieves 550 V as output where the input is variable. The fuzzy logic controller enables the integration of multiple power sources by selectively turning the ON and OFF switches in various operating modes. Fewer active switches during the powering process make it possible to employ semiconductors with a lower voltage. Thus, the converter generates high power with low conduction and switching losses. The state space model verifies the validity and stability of the converter under various operating modes. • Battery and PV array are integrated with the fuel cell using the single inductor multi-input converter (SI-MIC). • Fuzzy logic controller is used for switching the semiconductor devices for operating in various modes. • Battery can be charged and discharged in standby and normal operating modes. • Even if the input voltage fluctuates, the output voltage is always maintained at 550 V. [ABSTRACT FROM AUTHOR]

The paper introduces a step-down converter that exhibits a static conversion ratio of cubic nature, providing an output voltage which is much closer to the input voltage, and at the same duty cycle, compared to a wide class of one-transistor buck-type topologies. Although the proposed topology contains many components, its control is still simple, as it employs only one transistor. A dc analysis is performed, the semiconductor stresses are derived in terms of input and output voltages and output power, revealing that the semiconductor voltage stresses remain acceptable and anyway lower than in other cubic buck topology. All detailed design equations are provided. The state-space approach is used to analyze the converter in the presence of conduction losses and a procedure for calculating the individual power dissipation is provided. The feasibility of the proposed cubic buck topology is first validated by computer simulation and finally confirmed by an experimental 12 V–10 W prototype. [ABSTRACT FROM AUTHOR]

This paper proposes a simple design scheme for a modular NPC inverter using thermal RC network analysis. The proposed design process is an efficient and straightforward approach to designing the heatsink for a 300 kW modular neutral-point-clamped inverter. The heatsink design plays a crucial role in achieving high power density of a power converter because the weight and size of the heatsink are primarily influenced by its type. The structure and dimensions of the heatsink are mainly determined based on the generated heat by losses of the power semiconductor switches. In this paper, a thermal RC network model was established using parameters from the power switch module and was applied to the simulation of the power converter. The thermal losses of the power semiconductor switches were calculated via this process, and the heatsink was designed according to the calculated thermal losses. The proposed design scheme was analyzed and compared with the thermal fluid dynamic model. To validate the feasibility of the proposed design process, The simulation results were compared with experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical analysis of steady-state operation, control-oriented modeling for voltage control, and the experimental results of a DC–DC bidirectional converter based on a Cuk converter using a voltage-doubler concept. Due to the voltage-doubler concept, the voltage stress across semiconductors is reduced when compared with the conventional Cuk converter; this allows for the use of semiconductors with reduced drain–source on-resistance. Moreover, due to the input and output current source characteristics, the converter presents advantages, such as draining/injecting currents on both sides with low-ripple currents. Furthermore, the theoretical analysis is verified by experimental results obtained from a proof-of-concept prototype designed with a 250 V input voltage, a 360 V output voltage, 2 kW rated power, and 100 kHz switching frequency. [ABSTRACT FROM AUTHOR]

In DC microgrids, CLLC topology is commonly applied for battery integration. It provides galvanic separation, the ability to integrate a high-frequency transformer into the resonance circuit, and the ability to operate in a wide range of voltage. Moreover, it assures zero voltage switching conditions for all switches and zero current switching conditions for secondary side switches, which enables obtaining high efficiency. This paper presents a clear and effective approach to design a methodology for a CLLC DC/DC converter, especially a resonant tank. High-frequency transformer is fully integrated in a resonant tank. Its size is minimal and based on area product parameter A p . An equivalent scheme for first harmonic approximation analysis is presented with inclusion of parasitic elements. Based on it, the analytical formulas are provided, which enable graphical determination of working characteristics. It was proved that the model increases the accuracy of the results. The conditions of ZVS and maximal magnetizing inductance are established, including parasitic capacitances of secondary side switches and transformer parasitic capacitances. Based on the proposed design methodology, as the proof of concept, a small-power prototype with a GaN transistor was built operating at 364 kHz. Converter losses were determined through analytical expressions and compared with the experimental and simulation results. [ABSTRACT FROM AUTHOR]

Purpose: Five-level rectifiers have received widespread attention because of their excellent performance in high-voltage and high-power applications. Taking a five-level rectifier with only four-IGBT for this study, a sliding mode predictive control (SMPC) algorithm is proposed to solve the problem of poor dynamic performance and poor anti-disturbance ability under the traditional model predictive control with the PI outer loop. Design/methodology/approach: First, mathematical models under the two-phase stationary coordinate system and two-phase synchronous rotating coordinate system are established. Then, the design of the outer-loop sliding mode controller is completed by establishing the sliding mode surface and design approach rate. The design of the inner-loop model predictive controller was completed by discretizing the mathematical model equations. The modulation part uses a space vector modulation technique to generate the PWM wave. Findings: The sliding mode predictive control strategy is compared with the control strategy with a PI outer loop and a model predictive inner loop. The proposed control strategy has a faster dynamic response and stronger anti-interference ability. Originality/value: For the five-level rectifier, the advantages of fast dynamic influence and parameter insensitivity of sliding mode control are used in the voltage outer loop to replace the traditional PI control, and which is integrated with the model predictive control used in the current inner loop to form a novel control strategy with a faster dynamic response and stronger immunity to disturbances. This novel strategy is called sliding mode predictive control (SMC). [ABSTRACT FROM AUTHOR]

Summary: A novel transformerless three‐phase unidirectional bridgeless flying capacitor (UBFC) rectifier for medium‐voltage and high‐voltage applications is presented in this paper. The rectifier consists of three single‐phase rectifiers in wye connection; the DC outputs of the three single‐phase rectifiers are connected in parallel to provide a high common DC‐link bus, which makes it convenient to connect with neutral point clamped (NPC) or flying capacitor (FC) multilevel inverters. To avoid phase‐to‐phase current circulation, an additional inductor and diode are added to each single‐phase rectifier. Compared with conventional bidirectional multilevel converters, only half IGBTs are used, the voltage stress is lower, and the line‐frequency transformers are no longer required, which makes the proposed rectifier has a series of advantages such as reduced cost, simplified control complexity, increased reliability and improved overall efficiency. The basic operating principle of the proposed rectifier in continuous conduction mode is discussed; an improved carrier‐based level‐shifted pulse‐width modulation (PWM) method integrated with voltage balancing and the double closed‐loop control strategy are proposed to achieve more voltage levels and keep the flying capacitors in balance. The feasibility of the proposed rectifier is verified by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Summary: In this study, a novel non‐isolated DC‐DC converter based on magnetic coupling and voltage multiplier technique has been proposed. The output voltage of the suggested converter can be enhanced by selecting the appropriate turn ratio of the coupled inductor. To further improve the voltage gain, a voltage multiplier circuit including the capacitors and diodes has been utilized in this converter. The main features of the proposed converter are a high voltage conversion ratio, high efficiency, and lower peak voltage throughout the semiconductor devices. Besides, there are soft switching conditions throughout the diodes of the presented topology, which leads to reducing the reverse recovery losses of the diodes and subsequently improving the overall efficiency of the system. Also, only one insulated‐gate field‐effect transistor (MOSFET) has been used in the structure of the converter. Thus, the switch with lower on‐state resistance can be selected for the suggested converter that decreases the conduction losses. To prove the performance of the suggested structure, the operational analysis, mathematical descriptions, efficiency analysis, and comparison survey with similar structures in the literature have been described. Finally, a laboratory prototype with 200 W output power with 95.14% load efficiency, 20 V input voltage, and 260 V output voltage at 50 kHz switching frequency has been provided. [ABSTRACT FROM AUTHOR]

Converter steelmaking is a key part of steel production, and the resulting converter gas contains a large amount of CO2. CO2 capture of converter gas can benefit the reduction of CO2 emissions in the steel industry. In this study, a post-combustion capture process based on monoethanolamine (MEA) was established in Aspen Plus, and the absorption and desorption performance of MEA on converter gas were investigated by simulation using the thermodynamic model of ELECNRTL. Increasing the depletion flow rate, temperature, and MEA concentration can help to improve the CO2 capture rate; the feed position and desorption pressure affect the CO2 desorption effect, and the best desorption effect is achieved when the feed position is the second tray, and the desorption tower pressure is 1.9 bar. The results of the study can provide a new idea for CO2 capture at the end of converter steelmaking, which is of great significance for the progress of CCUS technology in the iron and steel industry. [ABSTRACT FROM AUTHOR]

The results of the design of integrated multistage voltage multipliers as components of supply modules for wireless passive microdevices are presented. The parameters of transistors that are significant for the construction of multipliers are considered for three typical CMOS technologies: CM018G 180 nm, HCMOS8D 180 nm, and C250G 250 nm. The Cadence CAD simulation results demonstrate that when implementing an eight-stage multiplier using the CM018G technology, the minimum output voltage level required for operation of the microcircuit is achieved at input amplitude of 250 mV; and when implementing a similar device using the HCMOS8D technology, at an amplitude of 375 mV. Using the example of the constructed 16-stage multiplier, it is shown that the voltage multiplication efficiency values range from 20 to 54% for a wide range of the input voltage, and the efficiency decreases only by 1–3% compared to the 8-stage implementation. The proposed recommendations for the design of integrated voltage rectifiers-multipliers can be used in the development of the passive supply units for microelectronic devices. [ABSTRACT FROM AUTHOR]

This paper presents an innovative cross-coupled differential drive rectifier for dual-band Radio frequency identification (RFID) tags. A self-compensating rectifier with enhanced power-conversion efficiency (PCE) at low and high RF power is proposed. The proposed rectifier utilizes a self-compensating circuit, the extra two cross-couple transistors, to increase the gate voltage of transistors to control the conduction of the rectifying transistors. In order to adapt high frequency (HF) and ultrahigh frequency (UHF) rectification, the matching circuit is designed with parasitic cancellation technology. Moreover, the cascading power management circuits are added to generate a stable output voltage. The multi-standard rectifier is designed and simulated in 0. 1 8 μ m CMOS process. The simulated result shows that the proposed three-stage rectifier achieves a PCE 74% (at 5 0 0 k Ω load) when receiving a 915 MHz signal with average power of − 2 5 dBm. Moreover, the maximum efficiency achieves 56% at HF 13.56 MHz, and the final output voltage can be stabilized at a specific voltage of 1.052 V. [ABSTRACT FROM AUTHOR]

Summary: This research paper introduces a novel active building block for full/half‐wave (inverse) rectifier circuits, eliminating the need for passive elements. The paper presents two alternative implementations: a current mode approach utilizing MO‐CFTA (multiple output current follower transconductance amplifier) and a transconductance mode approach utilizing MO‐VDTA (multiple output voltage differencing transconductance amplifier). Both circuit configurations exhibit favorable zero‐crossing characteristics and exceptional linearity. The transconductance mode rectifier enables electronic control of the output current signal by adjusting the applied bias currents. The circuits are designed with simplicity and compactness in mind, making them highly suitable for integration into IC circuits. The analysis investigates the impact of non‐idealities and parasitic effects, although the absence of passive elements results in minimal parasitic effects. Simulation results conducted using 0.18‐μm CMOS technology and a ±0.9‐V supply voltage align closely with the theoretical predictions. Furthermore, Monte Carlo simulations and corner analysis are employed to evaluate the circuit's robustness. To validate the feasibility of the proposed solution, experimental tests are performed using commercially available components. The designs are implemented on Cadence Virtuoso, and post‐layout measurements are conducted to further verify the proposed solutions. [ABSTRACT FROM AUTHOR]

The commutation failure is the most prevalent fault in line‐commutated converter based high‐voltage direct current systems, which may result in transient overvoltage on the sending‐side system. Overvoltage level evaluation has become a crucial task for power industries to assess the tripping risk of large‐scale wind turbines and implement effective stability control measures. In this paper, a derivation of the mathematical relationship between the reactive power consumed by the rectifier and AC voltage is presented firstly, along with an analytical expression for the peak value of transient overvoltage. Secondly, decision tree (DT) model is adopted to extract the mapping relationship between transient overvoltage and massive electrical quantities of power grids. The common DT algorithm is transformed by modifying the error weight assignment, which reflects the error tolerances for different actual overvoltage regions. On this basis, an overvoltage analysis method integrating the model‐driven and data‐driven techniques is proposed, and the improved DT algorithm is applied to fast error correction, enhancing the interpretability of regression prediction results. Case studies were performed in the simulation system of Northwest China local power grid with transient overvoltage problems, and the simulation results verified the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The modular multilevel converter-based high-voltage direct current (MMC-HVDC) transmission system has become a practical solution for interconnecting renewable energy sources to main AC grids. The MMC-HVDC has different parts, such as the converter, transmission system, and control system. The control system is the main part of the MMC-HVDC. Controlling the MMC-HVDC system is challenging due to various parameters, such as internal and external converter dynamics, transmission system configurations, and AC grid strength. This paper focuses on the control methods for internal and external converter control while considering grid strength. Firstly, an overview of the MMC topology, transmission system configurations, modeling, and AC–DC system strength will be presented. After that, the control methods for internal converter control and external converter control will be reviewed. This paper also highlights the features and drawbacks of each control loop. Finally, several comments and concluding remarks will be presented. [ABSTRACT FROM AUTHOR]

While the monolayer sheet is well-established as a Mott-insulator with a finite energy gap, the insulating nature of bulk 1T-TaS2 crystals remains ambiguous due to their varying dimensionalities and alterable interlayer coupling. In this study, we present a unique approach to unlock the intertwined two-dimensional Mott-insulator and three-dimensional band-insulator states in bulk 1T-TaS2 crystals by structuring a laddering stack along the out-of-plane direction. Through modulating the interlayer coupling, the insulating nature can be switched between band-insulator and Mott-insulator mechanisms. Our findings demonstrate the duality of insulating nature in 1T-TaS2 crystals. By manipulating the translational degree of freedom in layered crystals, our discovery presents a promising strategy for exploring fascinating physics, independent of their dimensionality, thereby offering a "three-dimensional" control for the era of slidetronics. While monolayer of 1T-TaS2 is considered to be a Mott insulator, the nature of the bulk insulating state is debated. Here the authors introduce a ladder-type structures with fractional misalignment of adjacent layers, showing that it becomes a Mott insulator due to decoupling between the layers. [ABSTRACT FROM AUTHOR]

This article aims to realize the brushless operation of a wound rotor vernier machine (WRVM) by a third-harmonic field produced through stator auxiliary winding (X). In the conventional model, a third-harmonic current is generated by connecting a 4-pole armature and 12-pole excitation windings serially with a three-phase diode rectifier to develop a pulsating field in the airgap of a machine. However, in the proposed model, the ABC winding is supplied by a three-phase current source inverter, whereas the auxiliary winding (X) carries no current due to an open circuit. The fundamental MMF component developed in the machine airgap creates a four-pole stator field, while the third-harmonic MMF induces the harmonic current in the specialized rotor harmonic winding. The rotor on the other side contains the harmonic and the field windings connected through a full-bridge rectifier. The electromagnetic interaction of the stator and rotor fields generates torque. Due to the open-circuited winding pattern, the proposed machine results in a low torque ripple. A 2D model is designed using JMAG-Designer, and 2D field element analysis (FEA) is carried out to determine the output torque and machine's efficiency. A comparative performance analysis of both the conventional and proposed topologies is discussed graphically. The quantitative analysis of the proposed topology shows better performance as compared to the recently developed third-harmonic-based brushless WRVM topology in terms of output torque and torque ripples. [ABSTRACT FROM AUTHOR]

The three-phase voltage type Pulse Width Modulation (PWM) rectifier is widely used in the front-end power factor of electric vehicle wireless charging systems due to its simple control structure and easy implementation. The system often adopts a double closed-loop PI control method based on voltage and current, which inevitably leads to a significant starting current surge and poses significant risks to the safe operation of the equipment. On the basis of establishing a mathematical model for PWM rectifiers, this article analyzes in detail the causes of starting over-current and designs a starting strategy with a voltage outer proportional and integral separated active current directly given. Simulation experiments show that this method can reduce the starting over-current of PWM rectifiers and the excessive DC voltage surge towards normal operation during the starting process. [ABSTRACT FROM AUTHOR]

This work proposes a new conception of the global microstrip rectenna system operating around 2.45 GHz. This improved rectenna system associates a receiving antenna with a rectifier circuit. This rectenna is printed on an FR4 substrate. The proposed antenna is a 1x4 microstrip antenna patch array with pentagonal patches using the defective ground structure method and operates with circular polarization. To show the effectiveness of this array, the results obtained by the computer simulation technology microwave studio (CST MWS) software prove that this array is good in terms of high gain, high directivity, high efficiency, wideband, small volume, and well-adaptation, and all these results are confirmed by another solver high-frequency structure simulator (HFSS). The improved rectifier is a microstrip rectifier that uses an HSMS2852 Schottky diode by using a series topology. The effectiveness of this rectifier is proved by the simulation results using advanced design system (ADS) software in terms of well-matching input impedance, high efficiency, and important output direct current (DC) voltage value. The proposed rectenna system is more efficient compared with the existing works and is very appropriate for several applications of wireless power transmission to power supply electronic instruments in various fields cleanly on our planet. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive comparative evaluation of a three-phase Three-Level (3L) Flying Capacitor Converter (FCC) and a Stacked Polyphase Bridge Inverter (SPBI), specifically a converter system formed by two Series-Stacked Two-Level three-phase Converters (2L-SSC), for the realization of a 7.5 kW Integrated Motor Drive (IMD) with a high short-term overload capability. The 2L-SSC requires a motor with two three-phase windings and a split DC-link, but uses standard six-switch, two-level transistor configurations. In contrast, the bridge legs of the 3L-FCC feature flying capacitors whose voltages must be actively balanced. Despite the 800 V DC-link voltage, both topologies employ the same set of 650 V GaN power transistors, i.e., the same total chip area, and if operated at the same switching frequency, show identical semiconductor losses. Electric Discharge Machining (EDM) damage of the motor bearings is a relevant issue caused by the common-mode (CM) voltages of the inverter stage. The high effective switching frequency of the 3L-FCC and the possibility of CM voltage canceling in the 2L-SSC facilitate mitigation of EDM by means of CM chokes, whereby a substantially smaller CM choke with lower losses suffices for the 2L-SSC; based on exemplary designs, the 2L-SSC features only about 75% of the total volume and 85% of the nominal losses of the 3L-FCC. If, alternatively, motor-friendliness is maximized by including DC-referenced sine-wave output filters, the 3L-FCC's higher effective switching frequency and the 2L-SSC's need for two sets of filters due to the dual-winding-set motor change the outcome. In this case, the 3L-FCC features only about 60% of the volume and only about 55% of the 2L-SSC's nominal losses. [ABSTRACT FROM AUTHOR]