High Power Capacity Research Articles

A UWB Metal Waveguide Slot Array Antenna Based on Hybrid Resonant Structural Components

Due to their high reliability, anti-interference, and power capacity, metal waveguide slot array antennas are commonly used in harsh and extreme working conditions. However, the fractional bandwidth of waveguide slot array antennas is usually not wide enough (<20%), which limits the performance of the microwave system. Aiming at expanding the bandwidth, this letter proposes a metal slot array antenna utilizing hybrid resonant structures. Five resonance frequency points are simultaneously excited and are subtly arranged, resulting in a great expansion of the working frequency band. The measured results of the metal slot array antenna demonstrate that the working frequency band is from 7.35 to 10.05 GHz and the fractional bandwidth is expanded to 31%. The average realized gain is 15 dBi and the polarization is lower than −20 dB in the whole working frequency band. Therefore, this ultrawideband metal slot array antenna can not only enable the electronic equipment to work in harsh environments, such as space, but also improve the system performance in applications, such as wideband satellite communication and wideband radar imaging.

Research on vibration characteristics of the longitudinal-radial composite piezoelectric ultrasonic transducer

The transducer with high power capacity and extensive radiating area is required in some industrial processes like ultrasonic sonochemistry, ultrasonic cleaning and ultrasonic defoaming and so on. In order to achieve the desired effects, the longitudinal-radial composite piezoelectric ultrasonic transducer is proposed in this paper. The transducer is composed of a longitudinal sandwich piezoelectric transducer, a stepped ultrasonic horn and a metal sphere. The longitudinal vibrations of the sandwich piezoelectric transducer and the stepped ultrasonic horn excite the radial vibration of the metal sphere so that the longitudinal-radial coupled vibration of the transducer is achieved. The equivalent circuits for a sphere in radial vibration and for the entire system in longitudinal-radial coupled vibration have been developed. To validate the proposed equivalent circuits, the vibration characteristics of the transducer are investigated using the equivalent circuit method, numerical method, and experiment. The resonance frequencies obtained from the equivalent circuit method, numerical method and experiment are 29992 Hz, 29990 Hz and 30590 Hz, respectively, and the simulated and experimental results indicate that the frequencies correspond to the designed longitudinal-radial coupled resonance mode of the transducer. The measured frequency and displacement distribution showed good agreement with the analytical and numerical calculation results.

Compact, High Power Capacity, and Low Insertion Loss Millimeter-Wave On-Chip Limiting Filter With GaAs PIN Technology

In this paper, a collaborative design of compact, high-power capacity, and low insertion loss millimeter-wave limiting filter using gallium arsenide (GaAs) PIN technology is presented. Parallel topology is employed to distribute the PIN diodes of the first stage of limiting circuit for high power handling capacity. In order to reduce the circuit size, the filtering function structure is incorporated into the limiter. Four transmission zeros (TZs) are introduced to improve the out-of-band suppression performances of the limiting filter. By utilizing the inductive short-circuited stub, a parallel resonator is introduced to exhibit the passband characteristic. Semi-lumped and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type topologies are employed to reduce the size of the conventional quarter-wavelength transmission line and introduce several TZs within the stopband. An on-chip limiting filter sample is fabricated by the GaAs PIN process and occupies an area of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 0.9$ </tex-math></inline-formula> mm2. It is measured with the insertion loss of 1.67 dB at the center frequency of 35 GHz, the stopband suppression of better than 20 dB, and the tolerable input power of greater than 40 dBm. Compared with the traditional designs, good features of high-power capacity, low insertion loss, and miniaturization are obtained with the presented on-chip limiting filter.

High-Power Microwave Limiters Using Recess-Free AlGaN/GaN Schottky Barrier Diodes

In this letter, a thin-barrier AlGaN/GaN Schottky barrier diode (SBD) is proposed and implemented in a three-stage high-power RF limiter module. Benefited from the thin-barrier epitaxy, a recess-free process in the Schottky region is allowed to avoid the plasma damage, resulting in low ON-resistance of 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> and high withstand voltage characteristics. In addition, the proposed SBDs have achieved a low junction capacitance of 0.35 pF at 0 V bias and a turn-on voltage of 0.5 V. With the optimized SBD and well-designed matching circuits, the limiter has reached a high power capacity of over 10 W in continuous wave (CW), 20 W in pulse mode, and a fast recovery time of 30 ns at a frequency of 3.5 GHz, exhibiting better characteristics than traditional limiters. Both simulation and measured results agree with each other. It indicates that the AlGaN/GaN-based SBD is promising for high-power and high-frequency limiters.

A Method to Characterize the Shrinking of Safe Operation Area of Metallized Film Capacitor Considering Electrothermal Coupling and Aging in Power Electronics Applications

Metallized film capacitor (MFC) selection is a key step to ensure the safe and reliable operation of high-capacity power electronic equipment. However, as a crucial factor leading to overstress failure, the changing of stress tolerance boundary caused by parameter drift and insulation deterioration has not been fully considered in capacitor design. Therefore, the establishment method of MFC lifecycle safe operation area (SOA) is proposed innovatively in this article, which characterize the shrinking of safe operating boundaries caused by electrothermal coupling and capacitor aging during long-term operation. First, the failure mechanisms and electrothermal coupling of MFC are discussed and the modeling process of initial SOA is proposed based on the datasheet and dc withstand voltage experiments. In addition, considering the increase of the hot-spot temperature and the decrease of breakdown strength due to equivalent series resistance parameter drift and dielectric insulation degradation in the whole lifecycle, the shrinking of MFC operation boundary is characterized and the modeling process of lifecycle SOA is proposed based on aging model and lifetime tests. Finally, taking an MMC system as example, the MFC selection based on practical operating condition and lifecycle SOA is performed to verify the validity of the method.

Enhanced magnetic refrigerant capacity power in Dy3Ni2 melt-spun ribbons by controlling the solidification rate

Both mechanical and magnetic properties of Dy3Ni2 ingots and melt-spun ribbons were investigated in the present work. The melt spinning rate has an important effect on their performance. The higher the melt spinning rate, the better the ductility, the larger the coercive force of ribbons. With increasing the spinning rate, the intensity of the diffraction peak suggesting the presence of polycrystalline becomes weaker and weaker, and eventually disappeared. The magnetic phase transition temperature is decreased from 66 K to 38 K with increasing the spinning rate. All samples undergo a second order paramagnetic-ferromagnetic phase transition. The full-width-at-half maximum of the temperature dependence of magnetic entropy change curve in Dy3Ni2 ribbons was much larger than that of Dy3Ni2 ingot. So a high refrigerant capacity power about 530 J.kg−1 of Dy3Ni2 ribbons was achieved.

Review on Cathode Materials for Sodium‐ and Potassium‐Ion Batteries: Structural Design with Electrochemical Properties

AbstractAs a promising candidates for next‐generation secondary battery system, sodium‐ion (Na‐ion) batteries and potassium‐ion (K‐ion) batteries are recently attracting considerable attention because of their cost‐effectiveness and similar reaction mechanism to that of lithium‐ion batteries. However, the major challenges for their practical application are sluggish ionic kinetic with excessive volume change of the cathode material, caused by larger ionic radius than Li+ ion. The current demand for high energy density is not satisfactory with the electrochemical properties of the cathode materials for Na‐ion and K‐ion batteries studied so far, but extensive studies have been conducted to achieve large reversible capacity, high power capacity, and long life in recent years. This review provides comprehensive information on the cathode material studies reported to date for Na‐ion and K‐ion batteries, with a particular focus on the various strategies of each cathode material to achieve high electrochemical properties. In this regard, diverse electrochemical properties of cathode materials for Na‐ion and K‐ion batteries are compared with current Li‐ion battery systems, and future research directions are discussed along with related challenges and prospects.

Asymmetric modulation of bridgeless single‐stage full‐bridge AC–DC converter for active power factor correction and zero voltage switching

AbstractSinge‐phase single‐stage AC–DC converters exhibit the advantages of lower cost, higher efficiency, and lower power semiconductor device count compared with traditional two‐stage topologies. However, most existing single‐stage AC–DC topologies encounter some or all the following drawbacks: hard‐switching operation, bulky bus or output capacitor, uncontrolled bus voltage, not actively shaped input current, a large amount of power semiconductor devices, etc. The bridgeless single‐stage full‐bridge AC–DC converter can be considered a promising solution for high power capacity and efficiency. However, this topology still suffers from most of the drawbacks. In this paper, a new asymmetric modulation method of bridgeless single‐stage full‐bridge AC–DC converter is proposed to achieve active power factor (PF) correction and zero‐voltage switching. Topology description, the proposed modulation and control methods, theoretical analysis progress, and reference design procedure are presented in detail. Finally, a 2‐kW laboratory prototype is implemented with experimental results presented to validate the principle and design.

High energy capacity or high power rating: Which is the more important performance metric for battery energy storage systems at different penetrations of variable renewables?

Studies exploring the role and value of energy storage in deep decarbonization often overlook the balance between the energy capacity and the power rating of storage systems—a key performance parameter that can affect every part of storage operation. Here, we quantitatively evaluate the system-wide impacts of battery storage systems with various energy-to-power ratios (EPRs) and at different levels of renewable penetration. We take Jiangsu province in China as our case study, due to its high electricity consumption and aggressive renewable energy targets. Our results show the evolving role of storage: as renewable penetration increases, higher EPRs are favored, as they lead to system-wide cost reductions, lower GHG emissions, and higher power system reliability. Whereas existing studies make exogenous assumptions about the lifetime of storage, we show that lifetimes across EPRs and renewable scenarios span 10 to 20 years. Existing research can thus send false signals to investors and grid planners, delaying the deployment of storage and retarding the energy transition. By showing how different EPRs yield different benefits at different stages of the energy transition, our results help investors, policy makers, and system planners design forward-thinking and dynamic policies that encourage prudent storage uptake.

High-Frequency Broadband RF Transmit-Receive Switch for Pulsed Magnetic Field NMR

The utility of high-field, high-frequency broadband pulsed magnetic field nuclear magnetic resonance (PMF-NMR) is significant in matter physics. The radio frequency (RF) transmit-receive (TR) switch is a kernel device used in nuclear magnetic resonance (NMR) spectrometers to switch signals between the two states of transmitting high-power RF pulses and receiving weak NMR signals. Most designs currently used in NMR have the disadvantages of a narrowband characteristic, low power capacity or large insertion loss, which make them unsuitable for high-frequency broadband PFM-NMR experiments. To improve the performance TR switches in PFM-NMR, a new design of an approximately symmetrical TR switch topology based on PIN diodes and multiple sections of coplanar waveguide lines with different impedances is introduced in this paper. By setting the parameters of the impedance lines and the values of the inductors and capacitors as variables and using the gradient optimization and the least square error evaluation function, we obtain excellent parameters for achieving the high-frequency broadband TR switch. The prototype of an active TR switch is designed and implemented for PMF-NMR with a band of 250 MHz-1 GHz, an insertion loss that is less than 0.56 dB, a switching time that is less than 0.9 μs and a high-power capacity of 200W.

Ni3S2 thin-layer nanosheets coupled with Co9S8 nanoparticles anchored on 3D cross-linking composite structure CNT@MXene for high-performance asymmetric supercapacitor

Supercapacitors attract tremendous research attention due to the cost-effectiveness, high power capacity and environment-friendly in the field of energy storage. In this work, Ni3S2 thin-layer nanosheets coupled with Co9S8 nanoparticles anchored on 3D cross-linking composite structure 5 mLCNT@MXene matrix (Ni/Co@C5M) was successfully synthesized via two-step hydrothermal and subsequent annealing treatment, possessing excellent electrochemical performance in terms of high rate capability, superior reversible capacity and outstanding durability. The electrode materials have distinct 3D cross-linking composite structure characteristics, which can significantly boost capacitive storage performance due to the introduction of CNT cross-linking conductive bridges and sulfides. Meanwhile, CNT can also prevent re-stacking of MXene layers and improve the electrical conductivity. As expected, the specific capacitance of Ni/Co@C5M electrode is 1827.5 F g−1 at 1 A g−1, which retains 88.57% after 10,000 cycles at a high current density of 30 A g−1 in cycling stability. Notably, an asymmetric supercapacitor (Ni/Co@C5M as the negative electrode and AC as the positive electrode, Ni/Co@C5M // AC) has exceptionally high energy density up to 78.4 Wh kg−1 at a power density of 699.3 W kg−1 and long capacitance retention of 86.67% at 20 A g−1 for 10,000 cycles. The designed Ni/Co@C5M // AC asymmetric supercapacitor in this work holds a promising future for the upgrading new high-performance energy storage device.

X-Band Active Phased Array Antenna Using Dual-Port Waveguide for High-Power Microwave Applications

An X-band active phased array horn antenna with high power capacity and high peak power is proposed in this paper. At the horn aperture, the baffles are loaded to suppress higher-order modes and eliminate blind spots during beam scanning. Straight walls are added to improve impedance matching. Considering that the peak power that T/R modules can provide is very limited, the proposal of a dual-port waveguide breaks through the bottleneck of the power capacity of a single-port input for the first time. The proposed curved dual-port waveguide is used to connect the horn antenna and the T/R module, which is verified to improve the power capacity of the overall internal structure. Simulated and measured results show that VSWR ≤ 2 in the frequency range of 7.5–8.5 GHz. There is no grating lobe in the ±10° scanning range and the maximum gain drop does not exceed 0.4 dB. The power capacity of the proposed HPM array is 56.34 MW. The phased array antenna has the characteristics of flexible scanning, small size, and high gain, and can be applied in high-power microwave systems.

A Novel Detachable Gate Driver Unit With Ultralow Inductance for Integrated Gate Commutated Thyristor

Under the background of clean energy connected to the grid, the high-capacity power electronics device integrated gate commutated thyristor (IGCT) has a bright future. In order to increase the convenience of replacement and longevity of service, a novel detachable gate driver unit (DGDU) concept for IGCT is proposed in this letter. To ensure the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> capability, both connection scheme and board optimization on DGDU are applied to minimize the stray inductance. Besides, the effects because of the detachable connecter on the structure and thermal characteristics are analyzed. Afterward, an overlapping scheme of DGDU with ultralow inductance is proposed for IGCT. Finally, a 4-inch prototype and a single-phase full-bridge platform are developed for the test. The turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> capability of DGDU is verified by pulse experiment, which could turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> a 5 kA current successfully. The stray inductance of DGDU is calculated based on the experimental result and is only 4% larger than conventional GDU, which means the commutation capability has little decrease. Furthermore, the continuous running reliability is verified by 2200 V-dc-voltage, 1300 A-effective-current power cycling experiments.

A bio-inspired fractal microchannel heat sink with secondary modified structure and sub-total-sub fluid transmission mode for high heat flux and energy-saving heat dissipation

With the rapid integration and miniaturization of electronic devices, thermal management has become one of the key factors restricting the development of microelectronic devices. The existing cooling methods consume enormous water and energy and destroy the environment and ecology. Therefore, a new heat dissipation technology is needed to meet the dual requirements of high heat flux heat dissipation capacity (HFHDC) and low power consumption. Inspired by the natural mass and energy transport ability of fractal structure, a composite microchannel with fractal microchannel serving as the main structure and secondary modified structure is proposed in this work to maintain high HFHDC and greatly reduce energy consumption of heat dissipation. Furtherly, a fluid guided layer providing high fluid distribution and lower pressure drop is designed to re-collect the distributed fluid at the end of the microchannel and discharge the cooling water. Compared with traditional design with single outlet, the temperature uniformity distribution can be improved and the pressure drop can be reduced by 46%. The simulation results show that under the temperature rise of 60 K, the heat flux of 577 W cm−2 (total heat power of 57.7 W) can be extracted by using the pumping power of 1.3 mW, and the coefficient of performance is as high as 43,465. This optimized design is fabricated by micro-machining processes, and the experiment data matches well with the simulation results. This work possesses high HFHDC, guarantees the trend of miniaturization of electronic system and greatly reduces the energy consumption for heat dissipation, providing a reference for low-power heat dissipation methods.

Propagation characteristics of radial phase-locked discrete vector beam generated from a Gaussian Schell-Model laser array in atmospheric turbulence

In this paper, combining the advantages of partial coherence, vector beam, and laser array in better resistance to atmospheric turbulence, high capacity, and high output power, we proposed a radial phase-locked discrete vector beam generated from a Gaussian Schell-Model (GSM) laser array (i.e., phase-locked GSM discrete vector beam array) and theoretically studied its propagation characteristics in atmospheric turbulence. The analytical expressions for spectral intensity, spectral degree of coherence (DOC), and spectral degree of polarization (DOP) of a phase-locked GSM discrete vector beam array were derived based on the extended Huygens-Fresnel principle. And also, based on numerical simulation, we investigated the influence of atmospheric and laser parameters on the propagation properties in detail. The results show that the beam profile will gradually evolve from hollow structure distribution, then form a flat-topped beam and finally present the Gaussian-like distribution; the spectral DOC exhibits decaying oscillation analogous to under-damping vibration; a dip appears in the distribution of the spectral DOP. The evolution rate of spectral intensity, oscillation amplitude, and period of spectral DOC and dip width of spectral DOP are determined by propagation distance, refraction structure constant, beam waist, spatial correlation length, and the number of beamlets. More importantly, by analyzing Stokes parameters, different initial polarization distributions correspond to different crosslines of S1/S0, and even with the increase of the propagation distance, the crosslines of S1/S0 still show similar performance. This work may provide novel thoughts and methods to improve propagation performance and benefit potential applications in free-space optical communication.

The Simulation Analysis of IGBT Module Based on COMSOL

IGBT, as the core device of high-capacity power electronic equipment, its stability is directly relevant to the normal operation of the equipment. It would cause system failure and major security incidents if aging failure phenomenon occurs. A complex multi-physical field coupling process is involved in the aging failure of IGBT. Based on Comsol software, this paper conducts a series of simulations on IGBT module model SKM50GB12T4, and also improves the simulation of the solder layer voids by combining with related literature on materials science to provide a basis for subsequent research on IGBT.

A Comparative Study on The Performance Analysis of Feature Extractors Used in Augmented Reality Applications Under Various Image Conditions

Until today, various approaches have been proposed in order to create Augmented Reality (AR) environment where virtual-real integration takes place. One of these approaches is vision-based model and it is divided into two branches as Marker-Based Augmented Reality (MBAR) and Markerless Augmented Reality (MAR). In the use of MBAR model, a reference image is introduced to the system before and when this image enters the camera view, an AR environment is created. However, in MAR model, no image is introduced to the system before. Instead, it uses natural characteristics present in the image such as edges, corners and geometrical shapes to create an AR environment. In order to use MAR model, it is necessary to use algorithms which require high processing power and memory capacity. Within the scope of this study, MAR model was chosen as reference and an evaluation on combinations of descriptive extractors (such as ORB, SIFT and SURF) and matchers (such as Bruteforce, Bruteforce-Hamming and Flannbase) was presented. In this context, it was aimed to obtain knowledge about i) the number of keypoints and detection time with use of different descriptor extractors, ii) the number of matching keypoints and the amount of positional deviation of a virtual object placed on a real world scene with use of different matchers. In line with this goal, analyzes were made using different image scales and brightness levels on both PC and mobile platforms. Results showed that, for both platforms, combinations using ORB method could work faster with less deviation than the combinations using other methods in all conditions. In addition, RANSAC algorithm was also used to reduce the total mean deviation ratio and it was seen that the rate could be reduced from 70% to 4.5%.

Devices for Thermal Conductivity Measurements of Electroplated Bi for X-ray TES Absorbers

Electroplated bismuth (Bi) is commonly used in transition-edge sensors (TESs) for X-rays because of its high stopping power and low heat capacity (Collan in Phys Rev B 1:2888, 1970, Yan in Appl Phys Lett 111:192602, 2017). Electroplated Bi is usually grown on top of another metal that acts as seed layer, typically gold (Au), making it challenging to extrapolate its thermoelectric properties. In this work, we present four-wire resistance measurement structures that allow us to measure resistance as a function of temperature of electroplated Bi independently of Au. The results show that the thermal conductivity of the Bi at 3 K is high enough to ensure the correct thermalization of X-ray photons when used as an absorber for TESs.

A Sub-THz High-Order Mode Backward Wave Oscillator Driven by Pseudospark Sourced Multiple Sheet Electron Beams

A novel concept of combining the advantages of pseudospark (PS)-sourced electron beam (high beam current density), multiple-sheet-electron-beams (large total beam cross-sectional area), and high-order mode (HOM) slow wave structure (SWS) (high power capacity) to produce high-power terahertz signals is presented in this article. As an example, a sub-terahertz backward wave oscillator (BEO) driven by PS-sourced dual-sheet-electron-beams is designed. Measured results of the interaction circuit, including transmission/reflection coefficients and the dispersion relation, were in good agreement with simulation predictions. Beam-wave interaction simulations having considered the plasma effect and conductor loss predicted stable output signals with radiation power of 167.4–255.4 W over a tunable bandwidth of 234.4–241.0 GHz.

Field and numerical modelling on the stability of underground strata in longwall workings

The longwall method is one of the feasible and efficient underground mining methods for greater depth of workings. Recently, Singareni Collieries Company Limited (SCCL), the largest coal-producing government company in the Southern part of India, has deployed a high capacity (2 × 1152T capacity) power support system in its Adriyala Longwall Project (ALP) at a depth of 375 m. There was a concern about the stability of the longwall workings and the protective pillars. Thus, research work was carried out with the geotechnical instruments and numerical modelling tools to analyze the stability while retreating the longwall panels. The outcomes revealed that the convergence in the gate roads increased with the longwall face advancement and the area of exposure. The pressure of the powered support legs on the dip side was less than the rise side legs, which implies a stable roof condition over the longwall face. An abutment zone was identified ahead of the line of extraction up to 10–25 m and presumed from the Factor of Safety (FoS) criterion that within this zone, the longwall pillar possibly will be of better stability at every stage of extraction. The results obtained from this study would be helpful for the mining engineers to understand the behaviour of underground strata in longwall workings.