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With the advantages of high power density, the hybrid axial transverse flux permanent magnet motor (HATF-PMM) is investigated in this paper. Eight topologies of the novel HATF-PMM are proposed, analysed and compared. The applicable scopes of different topologies are summarized and the optimal topology is selected. Based on the characteristics of hybrid flux motor, an indirect optimization method through magnetic circuit decoupling and recombination is proposed. The rotor parameter optimization is performed by the proposed indirect optimization method. In the end, the HATF-PMM scheme with high power density is obtained, and the optimization law of HATF-PMM rotor parameters is revealed through the optimization process, which proves that the HATF-PMM has great potential in the application of more-electric aircraft.

Permanent magnet synchronous motor (PMSM) is a special type of synchronous electric motor that has many applications such as in the manufacturing industry of robots, self-propelled mechanisms, in the medical fiel. In this paper, the permanent magnet synchronous motor motor control structure according to the field-oriented control (FOC) algorithm will be implemented on the field-programmable gate array (FPGA) card. Function blocks in FOC algorithm for example PI controller, space vector pulse width modulation (SVPWM) algorithm will be integrated into individual itegrated circuit (Ics) then will be connected to form an IC with the function of implementing FOC algorithm. Furthermore, this algorithm will be used for powertrains using gallium nitride (GaN). GaN technology provides switching frequencies up to 100 kHz instead of the upper 2 to 20 kHz like insulated gate bipolar transistor (IGBT) transistors. With GaN technology, it is possible to reduce switching losses as well as increase the efficiency of the power converter. The performance results will be verified through the typhoon hardware in the loop (HIL) device. [ABSTRACT FROM AUTHOR]

A zinc‐bromine redox flow battery (RFB) is highly suitable for high‐energy storage due to its decoupled energy and power generation. However, the poor kinetics and poor reversible behavior of Br2/Br− redox activity are some of the significant barriers, and as a result, the flow system delivers low power density. To increase the efficiency of the flow cell, in the present work, bimetallic catalysts are deposited on 3D graphite felt network and are used in the positive electrode for enhancing the kinetics of the Br2/Br− redox reaction. The platinum–nickel (PtNi) bimetallic composition is optimized, and the highly improved performances are investigated using half‐cell and flow‐cell assembly. The redox kinetics parameters are improved due to the high electro‐catalytic nature of the heat‐treated Ni‐rich PtNi coating on the graphite felt (GF) and the flow cell is operated up to 140 mA cm−2. The flow cell with Pt0.5Ni1@GF delivers an impressive ever‐best power density of around 1550 mW cm−2. The cycle life shows excellent stability up to 300 cycles with coulombic, voltage, and energy efficiency of 97%, 86%, and 83%, respectively. Thus, the present work offers a promising approach to developing effective electrode materials for obtaining a superpower RFB system. [ABSTRACT FROM AUTHOR]

Bromine polyhalide (BP) based redox flow batteries are considered as specific potential nominees for extreme energy level storage due to their high energy density as well as cost‐effectiveness. However, the BP system encountered with slow kinetics of Br2/Br− redox couple due to high positive electrode polarization results in poor power density. Herein, the heteroatom (nitrogen) doped reduced graphene oxide (N‐rGO) composite electrode is designed and used as a positive electrode to improve the electro‐catalytic activity of Br2/Br− redox couple. The cellulose (Rayon) based graphite felt incorporated with N‐rGO catalyst offers high conductivity and reduces the electrode polarization which in turn provides more catalytic sites for Br2/Br− redox reaction. N‐linked rGO preparation is carried out by two different methods namely, pyrolysis (thermally treated) and hydrothermally treated process called as HT‐N‐rGO@GF and Hy‐N‐rGO@GF, respectively. More impressively, the N‐rGO adopted graphite felt (N‐rGO@GF) exhibits remarkable rate performance even at 120 mA cm−2. Moreover, no detectable degradation is observed for both N‐rGO adopted felt over 100 cycles. The HT‐N‐rGO@GF and Hy‐N‐rGO@GF electrode shows 91.1% and 88.8% of Coulombic efficiency at 100th cycle respectively. On the other hand, the power density region of 1472 (HT‐N‐rGO@GF) and 1456 mW cm−2 (Hy‐N‐rGO@GF) are observed, which seems to be much better than that of pristine felt (1275 mW cm−2). [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors (LICs) feature a high-power density, long-term cycling stability, and good energy storage performance, and so, LICs will be widely applied in new energy, new infrastructure, intelligent manufacturing. and other fields. To further enhance the comprehensive performance of LICs, the exploration of new material systems has become a focus of research. Carbon nano-onions (CNOs) are promising candidates in the field of energy storage due to the properties of their outstanding electrical conductivity, large external surface area, and nanoscopic dimensions. Herein, the structure, composition, and electrochemical properties of carbon nano-onion-encapsulated Ni nanoparticles (Ni@CNOs) have been characterized first in the present study. The initial discharge and charge capacities of Ni@CNOs as anodes (in half-cells (vs. Li)) were 869 and 481 mAh g−1 at 0.1 A g−1, respectively. Even at a current density of 10 A g−1, the reversible specific capacity remained at 111 mAh g−1. Ni@CNOs were used as anode materials to assemble LICs (full pouch cells (vs. activated carbon)), which exhibited compelling electrochemical performance and cycle stability after optimizing the mass ratio of the positive and negative electrodes. The energy density of the LICs reached 140.1 Wh kg−1 at 280.2 W kg−1 and even maintained 76.6 Wh kg−1 at 27.36 kW kg−1. The LICs also demonstrated excellent cycling stability with a 94.09% capacitance retention over 40,000 cycles. Thus, this work provides an effective solution for the ultra-rapid fabrication of Ni-cored carbon nano-onion materials to achieve high-performance LICs. [ABSTRACT FROM AUTHOR]

Data centers require high efficiency and high power-density dc–dc converter with wide input range and galvanic isolation. To overcome the drawbacks of traditional single-stage LLC and two-stage solutions, a novel partial power regulation topology with wide input range is proposed in this article. The proposed topology delivers the load power through a three-ports LLC-based dc transformer regulated DCX (DCX). A pulsewidth modulation (PWM) converter is cascaded with one of the input ports of the DCX and then in series with the other input port to regulate the output voltage. Since a single transformer and a partial power PWM converter are employed, high power density can be achieved. Furthermore, only a portion of the load power is transferred by the PWM converter, the efficiency sacrifice is reduced. By introducing an appropriate negative current, the zero voltage switching of the PWM is also achieved. Furthermore, when the input voltage approaches the lower or the upper limit, the switching frequency of the PWM regulator can be ultralow. As a result, switching losses and core losses are further reduced. Finally, a prototype with 190—475 V input and 12 V/500 W output is demonstrated, which achieves a peak efficiency of up to 97.2% and a power density of 153 W/in3. [ABSTRACT FROM AUTHOR]

Compact autonomous ultrahigh power density energy storage and power generation devices that exploit the spontaneous polarization of ferroelectric materials are capable of producing hundreds of kilovolt voltages, multi-kiloampere currents, and megawatt power levels for brief interval of time. The storage life of these devices is four orders of magnitude longer than that for electrochemical batteries and electrochemical capacitors. Herein is an up to date survey of ferroelectric materials used for these high power devices. Several types of ferroelectric ceramics possess the ability to be depolarized under adiabatic compression and can be successfully used for high power applications. In addition to bulk ferroelectric ceramics, multilayer ferroelectric films are very efficient materials for high power systems. Of particular importance is the ability of relaxor ferroelectric single crystals to produce significantly higher electric charge density and energy density than ceramics, making them promising materials for high power applications. Also provided is a brief survey of recent developments of ferroelectric materials for high energy density and power density dielectric capacitors. Numerous ceramics have been developed, including antiferroelectric and relaxor antiferroelectric solid solutions, providing high energy density and efficiency simultaneously.

One of the most important trends for advanced diesel engines is downsizing, i.e., higher power density, which means more fuel is burned in a shorter period. In order to achieve rapid combustion for a high-power density diesel engine, the effects of bowl shape, diameter-to-depth ratio of bowl, and arrangement of nozzle holes on combustion and performance were investigated by CFD simulation. The effects of four bowl shapes, two of which were double-layer split bowls (DLSBs), as well as four diameter-to-depth ratios and three arrangements of nozzle holes were numerically assessed. The results show that the DLSB with a shallow dish-like structure yielded a remarkable effect of swirling flow by fuel splitting into upper- and lower-layer zones, which improved fuel–air mixing, shortened combustion duration, thus, resulting in high combustion efficiency and power density. Moreover, with the increase in diameter-to-depth ratio of the B type DLSB, the turbulent kinetic energy and the peak of pressure and heat release rate increased, further increasing power density. Finally, when the DLSB with a diameter-to-depth ratio of 2.0 is coupled with the staggered double-layer arrangement of nozzle holes, the in-cylinder mixtures became more uniform at both the circumferential and radial directions, and the combustion was considerably accelerated, achieving an optimum specific power of 122.6 kW·L−1. Meanwhile, there was a slight decrement for peak pressure and NOx emission, and smoke decreased by 49.1%, which revealed substantial improvement in reduction in mechanical load and emissions.

The isolated DC/DC converter connects the low-voltage direct current (LVDC) distribution network and the user-side DC load serving as an important equipment in LVDC distribution network. In this paper,LLC resonant converter with zero voltage switching on primary side and zero current switching on secondary side is adopted. The operation principles of LLC resonant converter are analyzed and the resonant parameters are presented. The gallium nitride device with lower on state resistance and effective output capacitance is used as the primary side switches to increase switching frequency and efficiency,thus decreasing magnetic component volume. Then,the driver of GaN devices,synchronous rectification and magnetic components are optimized and designed. Finally,a 375 V/48 V/500 W LLC resonant converter prototype is applied to verify the correctness of the design. The peak efficiency of the prototype is 97.6%,which is about 1% higher than that of the converter using traditional Si devices.

Abstract A zinc‐bromine redox flow battery (RFB) is highly suitable for high‐energy storage due to its decoupled energy and power generation. However, the poor kinetics and poor reversible behavior of Br2/Br− redox activity are some of the significant barriers, and as a result, the flow system delivers low power density. To increase the efficiency of the flow cell, in the present work, bimetallic catalysts are deposited on 3D graphite felt network and are used in the positive electrode for enhancing the kinetics of the Br2/Br− redox reaction. The platinum–nickel (PtNi) bimetallic composition is optimized, and the highly improved performances are investigated using half‐cell and flow‐cell assembly. The redox kinetics parameters are improved due to the high electro‐catalytic nature of the heat‐treated Ni‐rich PtNi coating on the graphite felt (GF) and the flow cell is operated up to 140 mA cm−2. The flow cell with Pt0.5Ni1@GF delivers an impressive ever‐best power density of around 1550 mW cm−2. The cycle life shows excellent stability up to 300 cycles with coulombic, voltage, and energy efficiency of 97%, 86%, and 83%, respectively. Thus, the present work offers a promising approach to developing effective electrode materials for obtaining a superpower RFB system.

Copyright of Electric Drive is the property of Electric Drive Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perovskite solar cells (PSCs), have exhibited potential value for revolutionizing photovoltaic technology for space applications, and they have passed a series of tests in a simulated space environment. Nevertheless, the simulated space environment on land is definitely distinguished from the real‐space conditions, and the results cannot completely represent the real operating state of PSCs in space. Herein, PSCs mounted on a high‐altitude balloon are launched into near‐space and the current–voltage characteristics are measured in situ throughout the 19‐h flight, during which the PSCs are exposed directly to near‐space and experience wide temperature variation, vacuum, and strong irradiation. Thus, the diurnal performance evolution of PSCs is obtained for the first time and a possible variation mechanism is identified. The PSCs present expected stability and a champion power density of ≈12 mW cm−2 at noon, which is demonstrated as the highest result achieved in near‐space for PSCs. Additionally, despite a complex degradation process, the PSCs still deliver a high energy density comparable to that of silicon solar cells. Finally, the challenges facing the space application of PSCs are discussed. This work highlights the feasibility of PSCs in near space and provides direction for further exploration. [ABSTRACT FROM AUTHOR]

The need of compact machines increased in recent years due to increases in raw materials' price. Hence, many studies are currently being conducted on high-speed challenges to propose an optimal design methodology. AC losses in windings are often not included in the optimization process and are treated in post-processing by choosing a suitable conductor's diameter to mitigate skin and proximity effects. This paper presents an optimization and design methodology for high-speed electric machines considering these losses, using models with an interesting trade-off between computation time and accuracy, which is helpful for large-scale optimization, in which more than 9,600,000 machines are evaluated. Optimizations are conducted on 100 kW high-speed one-layer V-shaped interior permanent magnet synchronous machines, widely used in vehicles thanks to their high power density, based on the specifications of the Peugeot e208, for different values of pole pairs and maximum speed. The influence of lamination thickness, fill factor, and maximum current density on the optimal design is also investigated. This paper concludes the utility of increasing speed to achieve high power density and proposes best alternatives regarding automotive constraints. Results show that the number of pole pairs is not always a key parameter in obtaining the lowest volume, especially at high speed. [ABSTRACT FROM AUTHOR]

Copyright of Automotive Digest is the property of Automotive Digest Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of a material modification method based on synergy of high-intensity ion implantation and simultaneous energy impact on the surface is aimed at creating deep ion-doped layers. To implement this method, the high power density of pulsed and repetitively-pulsed beams of metal and gas ions with micro-submillisecond duration are required. The paper presents the results of numerical simulation and experimental studies on the formation of pulsed high-intensity metal ion beams from vacuum arc plasma. The ballistic focusing of heavy ions at injection currents from 0.1 to 1 A has been studied. The influence of the ion current density, accelerating voltage, and conditions for neutralizing the beam space charge on the transport and focusing of a high power density ion beam has been studied. The possibility of ballistic formation of submillisecond titanium ion beams with a pulse power density of a hundred kilowatts per square centimeter has been experimentally shown. [ABSTRACT FROM AUTHOR]

Modular multilevel converter (MMC) faces challenges ofcost and footprint in medium and high voltage grid applications. By adding a three-phase switching bridge on the basis of MMC, this article proposes a three-phase multiplexing arm modular multilevel converter (TPMA-MMC) with high power density and small volume. The multiplexing principle for TPMA-MMC is investigated, showing the multiplexing arm can be multiplexed for one-third fundamental period. After that, the subsection modulation scheme is further proposed for energy balance purpose. Compared with MMC, the number of submodules (SMs) and power devices are reduced by 22.8% and 13.83%, respectively, resulting in lower construction cost. Meanwhile, the SMs’ capacitance and the total capacitor energy storage of TPMA-MMC reduce greatly with the subsection modulation, which can greatly reduce the footprint and improve the power density. Moreover, the proposed TPMA-MMC outperforms the MMC in terms of efficiency. Finally, the topology and proposed modulation scheme are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

The waveguide structure made of lithium niobate crystal (LiNbO3, LN) can further improve the device integration. It has been widely used in electro-optical modulator, frequency conversion, acousto-optic Q-switching and other optoelectronic devices. It has important application prospects in optical fiber communication, photoelectric sensing, lidar, aerospace and other fields. The LN waveguide made by traditional Ti diffusion method has poor resistance to photorefractive damage in short wave applications. The LN waveguide made by annealing proton exchange method only support TM mode (transverse magnetic mode) single polarization transmission, and its application field is limited. In this paper, a new Zn diffusion method is proposed to fabricate magnesium doped LN ridge waveguide. By establishing the diffusion model and simulation of the waveguide, the technological conditions were explored and tested. The lowest transmission loss of LN waveguide is 0.86 dB/cm, and the photorefractive damage threshold can reach 184 kW/cm². It will provide a better preparation way for the research and development of high power lithium niobate waveguide integrated optoelectronic devices. [ABSTRACT FROM AUTHOR]

This brief presents an optimal design of high power frequency transformer for flyback converter based on E-mode GaN device, which could be used in personal portable chargers. The new generation of wide band gap semiconductor GaN switch is used to improve the switching frequency of the circuit. The high-frequency magnetic core and the winding method of magnetic components are optimized. The leakage inductance of the transformer of magnetic components is greatly reduced. Consequently, the overall power density of the circuit is improved. The feasibility of the design scheme is verified by hardware implementation and experimental results. The test results show that compared with the traditional flyback magnetic element design, the volume of magnetic element is reduced by 30%. Meanwhile, the loss is reduced by 30%, and the peak efficiency of the converter can reach 94.2%. The ratio of leakage inductance of magnetic transformer to excitation inductance decreased from 2.2% to 1%. In addition, power density of the converter reached 20.26W/in3, which is much higher than the existing commercial ones. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel In-doped and Li 3 InO 3 coated single-crystalline Ni-rich cathodes are reported. • The serious Li/Ni disordering and sluggish Li-ion diffusion kinetics are ameliorated. • The as-obtained Ni-rich cathodes exhibits superior cycling stability and high-power density. Single-crystalline Ni-rich Co-poor cathodes operating at high-voltage are attractive owing to their higher energy density for meeting the requirements of next-generation Li-ion batteries, yet they usually suffer from sluggish Li-ion diffusion kinetics and serious Li/Ni disordering. Herein, an in-situ co-precipitation strategy is implemented to achieve the novel In-doped and Li 3 InO 3 coated single-crystalline LiNi 0.90 Co 0.05 Mn 0.05 O 2 cathodes with a highly ordered layered structure. The In-doping facilitates grain growth by decreasing the surface energy of crystal faces, reducing the synthesis temperature by about 20 °C, which thus drastically suppresses Li/Ni disordering and lattice oxygen loss. Furthermore, the pillar effect of In-ion doping and the in-situ formation of the ultrafast Li-ion conductive Li 3 InO 3 coating synergistically enhance the Li-ion diffusion kinetics. These merits enable the as-obtained Ni-rich Co-poor cathodes with a high reversible capacity of 229.4 mAh g−1 at 0.1C and 124.6 mAh g−1 at 7C. In a pouch-type full cell, 93.9 % of the initial capacity is still maintained after 500 cycles at 1C within 2.7–4.5 V. This finding opens up a new path for improving the rate performance and cycle life of single-crystalline Ni-rich cathodes for high-voltage Li-ion batteries. [ABSTRACT FROM AUTHOR]

This study presents a groundbreaking advancement in the field of ceramic fuel cells, namely, solid oxide fuel cells (SOFCs) and proton ceramic fuel cells (PCFCs). In contrast to the prevalent crystalline fluorite oxygen ion-conducting electrolytes and proton-conducting perovskite electrolytes, our study underscores the transformative potential of amorphous oxide material. The Nd-alumina amorphous oxide demonstrates exceptional proton conductivity, reaching 0.16 Scm−1 and an impressive power density of 713 mWcm−2 at 500 °C, thereby surpassing the capabilities of existing crystalline electrolyte materials. Furthermore, this study provides a comprehensive comparison between amorphous Nd-alumina and its crystalline counterparts, thus elucidating the inherent advantages of the amorphous form over traditional crystalline structures. Several characterizations and experimental methods have been introduced for in-depth analysis of proton and oxide ions migration in developed NdAl-Aos electrolytes. However, amorphous Nd-alumina emerges as an alternative component in ceramic fuel cells, propelling an electrolyte technology towards unparalleled performance and paving the way for a sustainable SOFC/PCFC future. • A Novel Nd–Al amorphous oxide electrolyte materials is developed for SOFCs. • Amorphous Nd–Al oxide has shown excellent proton conductivity at 500-300 °C. • Using Amorphous Nd–Al oxide peak power density of 713 mWcm−2 is achieved at 500 °C. • Special attention has been paid on protonic conduction mechanism and transport. [ABSTRACT FROM AUTHOR]

• A 5-cell stack model coupling electrochemistry and manifold configuration has been constructed. • Effects of manifold configuration and cooling intensity on PEMFC stack internal heat and mass transfer mechanisms is revealed. • The U-type configuration and increasing coolant velocity can effectively enhance stack performance and consistency. • Adequate cooling effectively improves temperature consistency but exacerbates concentration polarization. The heat transfer and mass transfer mechanisms in proton exchange membrane fuel cell (PEMFC) stacks are crucial for ensuring performance, consistency, and safety. A three-dimensional PEMFC 5-cell stack simulation model with cooling flow fields is developed to observation of the internal heat and mass transfer characteristics of the stack. This contributes to understanding the impact of the cooling flow field on performance. Results highlight the significant impact of coolant velocity on heat and mass transfer performance, adequate cooling effectively improves temperature consistency but exacerbates concentration polarization. Additionally, manifold configurations exhibit distinct effects. The U-type configuration not only exhibits superior single-cell consistency but also improves temperature uniformity under adequate cooling. At a current density of 3.6 A cm−2 and with adequate cooling, the Z-type configuration exhibits a maximum voltage difference of 117.52 mV, while the U-type configuration only exhibits 38.12 mV, indicating a difference exceeding 300 %. At high current densities, significant dead zones are present near the outlet side of each cell's flow field, where the oxygen molar fraction is nearly zero, which is a primary cause of concentration polarization. Under the Z-type configuration, the maximum difference in oxygen molar concentration among single cells reached 72 %. For stacks operating at high current densities, employing the U-type configuration and increasing coolant velocity can effectively enhance stack performance and consistency. [ABSTRACT FROM AUTHOR]

• ADlBs have characteristics of intrinsic safety, high power density, environmental friendliness. • ADlBs have broad application prospects in the future of large-scale energy storage. • We summarized the current research progress on ADIBs and their prospects. Aqueous dual-ion batteries (ADIBs) using aqueous electrolytes at different concentrations have several favorable characteristics over non-aqueous batteries, including intrinsic safety, high power density, environmental friendliness and easy recovery. Benefiting from these merits, ADIBs have broad application prospects in the future of large-scale energy storage. However, due to the oxygen/hydrogen evolution and other side reactions on the electrodes, which results in traditional aqueous electrolytes still suffer from low working voltages, poor electrode material stability, and narrow voltage windows. Therefore, research on ADIBs is still in the initial stage, and further development of these ADIBs requires additional research. This review aims to summarize and analyze the current research progress on ADIBs, involving reaction mechanisms, electrolytes, cathodes/anodes and corresponding carriers. Typical ADIBs, which are based on univalent/polyvalent cations and involve various selected anions, are evaluated here as the primary examples. The objective is to examine the advantages and disadvantages of ADIBs. In conclusion, future high-performance ADIBs are discussed, along with potential design strategies. This review aims to encourage practical application in the future. [ABSTRACT FROM AUTHOR]

This article presents a planar transformer design and optimization method for high power density on-board chargers (OBCs) utilized in electric vehicles (EVs). Owing to considerations of electrical safety, OBCs require an isolated converter, leading to a substantial increase in volume due to the inclusion of a transformer. To address this issue and achieve high power density, a planar transformer is used, and an optimized design method is proposed for pattern arrangement, width, and core shape. The feasibility of the design is verified through the development of a 3.3 kW OBC prototype. Consequently, when compared to conventional transformers, the design method in this article results in a 27% reduction in the transformer’s height and a 20% reduction in its overall volume. This reduction is advantageous for meeting the requirements of high power density OBCs.

A series resonant converter (SRC) operating as a DC transformer (DCX) is a candidate for the isolated bidirectional DC/DC converters of solid-state transformers (SSTs). However, the input/output current ripple of the SRC is relatively high, which requires bulky parallel capacitors and low-pass filters such as C/LC filters. These additional components reduce the power density. In addition, to operate an SRC as a DCX, a small resonant inductance is desired to reduce the voltage gain variation and achieve a faster transient response. To resolve these problems, a SRC with embedded filters is studied. Adding a clamping capacitor between split transformers not only significantly reduces current ripples and the harmonic components of the input/output currents but also connects resonant inductors in parallel to reduce the equivalent resonant inductance. In addition, dividing the resonant current into two split windings reduces the RMS current of the transformer. This paper presents a detailed analysis, a design methodology, and a comprehensive comparison with the conventional half-bridge CLLC converter with C/LC filters. 1-kW prototypes with a 600-V input voltage and 200-V output voltage demonstrate the superiority of the proposed converter; the second harmonic of the output current was significantly suppressed by 19.3 dB compared with that of the conventional converter with the same power density. The loss breakdown showed the proposed converter mitigated copper loss by 9.47% and eliminated the losses of the filter and DC-link capacitors. The prototype of the proposed converter had the highest efficiency of 95.4% at full-load among prototypes.

Abstract The growing demand for high-power-density electric and electronic systems has encouraged the development of energy-storage capacitors with attributes such as high energy density, high capacitance density, high voltage and frequency, low weight, high-temperature operability, and environmental friendliness. Compared with their electrolytic and film counterparts, energy-storage multilayer ceramic capacitors (MLCCs) stand out for their extremely low equivalent series resistance and equivalent series inductance, high current handling capability, and high-temperature stability. These characteristics are important for applications including fast-switching third-generation wide-bandgap semiconductors in electric vehicles, 5G base stations, clean energy generation, and smart grids. There have been numerous reports on state-of-the-art MLCC energy-storage solutions. However, lead-free capacitors generally have a low-energy density, and high-energy density capacitors frequently contain lead, which is a key issue that hinders their broad application. In this review, we present perspectives and challenges for lead-free energy-storage MLCCs. Initially, the energy-storage mechanism and device characterization are introduced; then, dielectric ceramics for energy-storage applications with aspects of composition and structural optimization are summarized. Progress on state-of-the-art energy-storage MLCCs is discussed after elaboration of the fabrication process and structural design of the electrode. Emerging applications of energy-storage MLCCs are then discussed in terms of advanced pulsed power sources and high-density power converters from a theoretical and technological point of view. Finally, the challenges and future prospects for industrialization of lab-scale lead-free energy-storage MLCCs are discussed.

This elaboration presents the concept of the design, parameters, experimental investigation, and thermal numerical model solved using the finite element method of a high-power-density DC–DC converter. The analyzed unit can be utilized as a stand-alone converter or as a module for a scalable high-voltage gain system. The converter has a decreased bill of materials since it does not use typical chokes and heatsinks. It is based on switched capacitor circuits supported by a resonant choke which protects against inrush currents. A printed circuit board is utilized not only for the resonant inductance design but also for cooling transistor and diode devices. The paper demonstrates the design concept and the achieved parameters. Experimental results show heat distribution on the printed circuit board and components in a steady state and dynamical states as well. The converter parameters and their efficiency are measured as well. The convergence of experimental results and heating simulations is demonstrated. The numerical model is used for the investigation of design cases. The printed circuit board size, thermal via pattern, and heating process during the overload of the converter are investigated. [ABSTRACT FROM AUTHOR]

In this work, we reported a novel preparation method for a proton exchange membrane (PEM) named, the direct electrostatic deposition method. In theory, any required thickness and size of PEM can be precisely controlled via this method. By direct electrostatic spraying of Nafion solution containing amino modified SiO2 nanoparticles onto a metal collector, a hybrid membrane of 30 μm thickness was fabricated. The DMFC assembled with a prepared ultrathin membrane showed a maximum power density of 124.01 mW/cm2 at 40 °C and 100% RH, which was 95.29% higher than that of Nafion. This membrane formation method provides potential benefits for the preparation of ultrathin PEMs. [ABSTRACT FROM AUTHOR]

This article proposes a two-stage power converter with novel control methods for pulsed load applications. The first stage is an isolated converter that transfers only average power to the second stage, which dramatically reduces the input filter size and components’ current rating. The second stage is a buck converter designed for a fast response during pulsed load transients. A flexible intermediate voltage is implemented to reduce the size of the midpoint energy storage capacitor that is responsible for compensating the instantaneous power difference between the two stages. A novel digital input feed-forward controller is proposed for the second stage to eliminate the poor line regulation issue caused by the flexible intermediate voltage. To verify the effectiveness of the two-stage power supply and the control methods, a full-scale 800 W (average)/4 kW (peak) converter prototype is built and tested. The results prove the feasibility of the proposed topology as well as control methods and demonstrate the advantages over traditional concepts. [ABSTRACT FROM AUTHOR]

Li-ion capacitors (LIC) have emerged as a promising hybrid energy storage system in response to increasing energy demands. However, to achieve excellent LIC performance at high rates, along with cycling stability, an alternative anode to graphite is needed. Porous high-surface-area carbons, such as onion-like carbons (OLCs), have been recently found to hold high potential as high-rate-capable LIC anodes. However, a systematic understanding of their synthesis route and morphology is lacking. In this study, OLCs prepared from self-made metal organic frameworks (MOFs) Fe-BTC and Fe-MIL100 by a simple pyrolysis method were compared to OLCs obtained via high-temperature annealing of nanodiamonds. The LICs with OLCs produced from Fe-BTC achieved a maximum energy density of 243 Wh kg−1 and a power density of 20,149 W kg−1. Furthermore, excellent capacitance retention of 78% after 10,000 cycles was demonstrated. LICs with MOF-derived OLCs surpassed the energy and power density of LICs with nanodiamond-derived OLCs. We determined the impact of the MOF precursor structure and morphology on the resulting OLC properties, as well as on the electrochemical performance. Thus, MOF-derived OLCs offer significant potential toward high-performance anode material for LICs, enabling control over structure and morphology, as well as easy scalability for industrial implementation. [ABSTRACT FROM AUTHOR]

A novel, oleic acid-assisted solution combustion synthesis route has been successfully explored to synthesize high surface area and mesoporous Al-doped LiMn2O4 nanosheets without the use of MnO2 templates. The as-synthesized LiMn2O4 nanosheets possess the typical electrochemical superiorities. The high surface area of 44.5 m2g−1, high porosity, and layered structure have been desirable and perquisites for enhanced supercapacitor applications. These nanosheets present strong (400) planes than normal, easing the charge transfer during electrochemical processes. An enhanced specific capacitance of 433 Fg−1 is obtained along with the enhanced rate capabilities. The high energy and high power density of 23.4 Whkg−1 and 4651 Wkg−1 respectively make the LiMn2O4 nanosheets an effective cathode material in supercapacitor applications. The novel solution combustion method provides an effective single-step approach to synthesize desired LiMn2O4 nanostructures for enhanced next generation energy applications. [ABSTRACT FROM AUTHOR]

The dc circuit breaker plays an important protection role in the dc distribution systems. Hybrid dc circuit breaker (HCB) offers low conduction losses and reasonably fast response times. In this article, a high power density, modular, and scalable power electronic interrupter (PEI) design is introduced for medium-voltage (MV) HCB platforms. Following this concept, the single low-voltage module is first investigated in terms of the high pulse current ratio and the voltage clamping circuit. After the comparison and test among different devices, a compact module with 1.7-kV discrete IGBTs are selected as main switches. While the voltage clamping circuit is carefully designed to guarantee no tail current bump and sufficient turn-off voltage margin. Next the whole system with series modules is optimized on the aspects of the turn-off strategy, power supply structure, and layout of modules. An improved staged turn-off scheme is proposed, which can not only reduce the peak current and total metal oxide varistor (MOV) energy, but also help balance the MOV energy distribution. A 12-kV and 1-kV breaking capable PEI was demonstrated based on the proposed PEI design, achieving a peak power density of 7.4 kW/cm3, much higher than the IGBT module-based solution. The breaking capability and effectiveness of the modular PEI is demonstrated in a 6-kV MVDC HCB device. [ABSTRACT FROM AUTHOR]

The effects of the electrochemical oxygen reduction reaction (ORR) on the surface of single-phase perovskite cathodes are well understood, but its potential for use in a complex system consisting of different material types is unexplored. Herein, we report how BaCO3 nanoparticles-modified La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.2Ce0.8O2-δ (LSCF–GDC)-composite cathodes improved the electrochemical oxygen reduction kinetics for high-performing ceramic fuel cells. Both X-ray diffraction (XRD) and thermogravimetric analysis (TGA) studies reveal that BaCO3 is stable, and that it does not show any solid-state reaction with LSCF–GDC at SOFCs' required operating temperature. The electrochemical conductivity relaxation (ECR) study reveals that during the infiltration of BaCO3 nanoparticles into LSCF–GDC, the surface exchange kinetics (Kchem) are enhanced up to a factor of 26.73. The maximum power density of the NiO-YSZ anode-support cell is increased from 1.08 to 1.48 W/cm2 via surface modification at 750 °C. The modified cathode also shows an ultralow polarization resistance (Rp) of 0.027 Ω.cm2, which is ~4.4 times lower than that of the bare cathode (~0.12 Ω.cm2) at 750 °C. Such enhancement can be attributed to the accelerated oxygen surface exchange process, possibly through promoting the dissociation of oxygen molecules via the infiltration of BaCO3 nanoparticles. The density functional theory (DFT) illustrates the interaction mechanism between oxygen molecules and the BaCO3 surface. [ABSTRACT FROM AUTHOR]

Integrated buck-boost-LLC (IBBL) dcconverter is a good solution for high efficiency and high power density applications. However, the bridge leg integration causes asymmetrical zero-voltage-switching process and asymmetrical secondary current. The method of high quality factor or symmetric phase shift modulation proposed in the existing research can improve the asymmetrical current issue under heavy load, but is ineffective for light load conditions. This article proposes a novel Interleaved IBBL converter to improve the asymmetry issue for whole load range. Interleaving makes the secondary current be symmetric naturally. In addition, a comprehensive optimal design method for phase-shift angle and choke inductor is proposed to minimize the total power loss of all primary elements. A 600 W/1 MHz prototype verifies that the proposed IIBBL converter achieves symmetric secondary current in whole load range, and it achieves 95.7% efficiency and 180 W/in3 under the proposed comprehensive optimal design method. [ABSTRACT FROM AUTHOR]

This article details the design of a permanent magnet synchronous electric motor prototype dedicated to the direct drive of the propeller for VTOL (Vertical Take-Off and Landing) and CTOL (Conventional Take-off and Landing) aircrafts. Our main aim is to maximise the power-to-weight ratio whilst not compromising the efficiency and the reliability. The originality of the research is based on the implementation of an armature winding using solid copper bars; we show that it is possible to use such an approach in an electric machine operating at very high frequency (1800 Hz) through a precise study on the shape of the bars to counter the additional losses. A prototype has been successfully manufactured; manufacturing details and some of the experimental test results are presented here. [ABSTRACT FROM AUTHOR]

The alignment stability and controllability deteriorate considerably when the air spring vibration isolation system for the high power density main engine (HPDME-ASVIS) is in a special running state of high power and high output torque. The coupling characteristics among the alignment components are obtained by analyzing the mechanical characteristics of HPDME-ASVIS. A control response model is established, which can predict the alignment state and the vertical displacement of air springs after k times of inflation/deflation. By solving the linear programming problem, the alignment controllability judgment models are constructed for two conditions, which are under hard constraints and soft constraints, respectively. Furthermore, alignment reconfigurability is described and an autonomous control method is established. The experimental results confirm that high output torque will cause large and serious coupling of horizontal offset, self-rotation angle, and vertical deformation of air springs. Meanwhile, hey cannot reach the given control precision range. The traditional control method under hard constraints will result in a state of oscillation and may bring many reliability problems to HPDME-ASVIS. The alignment reconfigurability analysis can judge the alignment control influence degree based on different torque accurately. The autonomous control can use the control parameters autonomous adjustment and the spatial configuration to realize the alignment control reconfigurability for two different alignment control fault states. The stability of the alignment control system in HPDME-ASVIS can be improved observably, which is of great significance to the engineering application of the high power density main engine (HPDME) in the field of marine propulsion technology. [ABSTRACT FROM AUTHOR]

An integrated inductor for a highly compact embedded battery charger is designed in this article. A zero-voltage switching (ZVS) buck converter is the selected topology to achieve high power density. ZVS is achieved by sizing the inductor based on energy balance and introducing the $k$ factor. A novel four-leg magnetic core structure is proposed as the integrated inductor. By introducing a modified parameter $\alpha _{\mathrm{eff}}$ to the improved generalized Steinmetz equation method, the optimal switching frequency for core losses can be found. From the constructed inductor model and semiconductor loss calculation, the design tradeoff and optimization is analyzed. The optimal $f_{\mathrm{sw}}$ is found to be around 2 MHz, which is when the performance factor for the core material peaks. As a proof of concept, a highly compact prototype, featuring stacked printed circuit board solution, with 16.2 × 19.2 × 6 mm $^{3}$ dimension is built. The input voltage ranges from 6 to 12 V, and the converter is capable of delivering up to 10 A at the 4-Voutput. Converter peak efficiency of 96% is achieved, and the inductor design has a power density of 113.6 W/cm $^{3}$. This shows improvement over several state-of-the-art designs. This article is accompanied by a video demonstrating the flux distribution in the magnetic core over the switching period. [ABSTRACT FROM AUTHOR]

Active combustion control (ACC) has been proved to be an effective method for the suppression of pressure oscillation in aero engine combustion chambers, which will seriously endanger flight safety of aircrafts. However, the actuators for ACC need to work with a bandwidth of 1000 Hz, a stroke up to submillimeter level and a high power density simultaneously. Existing electromagnetic actuators, or smart material actuators, are still unable to meet these requirements at the same time. To address this issue, in this article, a multidimensional discrete magnetostrictive actuator (MDMA) was developed by adopting the multidimensional discrete configuration. In order to obtain large output displacement while maintaining the characteristics of high bandwidth and high power density of magnetostrictive materials, tubular and cylindrical magnetostrictive rods are nested axially and radially through sleeves to form a discrete magnetostrictive stack; independent excitation coils and permanent magnet rings are integrated axially to form a discrete electromagnetic excitation system. Then, a magnetic equivalent circuit (MEC) model was developed to analyze the magnetic field distribution characteristic of MDMA components. Next, a multiphysics comprehensive dynamic model was established to describe the complex dynamic properties of multidimensional discrete structures. Subsequently, a prototype of the MDMA was fabricated, which is only 56 mm in diameter and only 71.5 mm high. Experimental results indicate that, the proposed MDMA reaches a stoke of 100 $\mu$ m, and the working bandwidth can exceed 1000 Hz. Furthermore, closed-loop control tests were conducted and the results showed that the MDMA can effectively track sinusoidal references of different amplitudes under low frequency with a feedback PID controller. [ABSTRACT FROM AUTHOR]

The application of hydrogen fuel in ORP engines makes the engine power density much higher than that of a reciprocating engine. This paper investigated the impacts of combustion characteristics, energy loss, and NOx emissions of a hydrogen-fuelled ORP engine by ignition timing over various equivalence ratios using a simulation approach based on FLUENT code without considering experiments. The simulations were conducted under the equivalence ratio of 0.5~0.9 and ignition timing of −20.8~8.3° CA before top dead centre (TDC). The engine was operated under 1000 RPM and wide-open throttle condition which was around the maximum engine torque. The results indicated that significant early ignition of the ORP engine restrained the flame development in combustion chambers due to the special relative positions of ignition systems to combustion chambers. In-cylinder pressure evolutions were insensitive to early ignition. The start of combustion was the earliest over the ignition timing of −17.3° CA for individual equivalence ratios; the correlations of the combustion durations and equivalence ratios were dependent on the ignition timing. Combustion durations were less sensitive to equivalence ratios in the ignition timing range of −14.2~−11.1° CA before TDC. The minimum and maximum heat release rates were 15 J·(°CA)−1 and 22 J·(°CA)−1 over the equivalence ratios of 0.5 and 0.9, respectively. Indicated thermal efficiency was higher than 41% for early ignition scenarios, and it was significantly affected by late ignition. Energy loss by cylinder walls and exhaust was in the range of 10~16% and 42~58% of the total fuel energy, respectively. The impacts of equivalence ratios on NOx emission factors were affected by ignition timing. [ABSTRACT FROM AUTHOR]

Aqueous aluminum ion batteries (AAIBs) possess the advantages of high safety, cost-effectiveness, eco-friendliness and high theoretical capacity. However, the Al 2 O 3 film on the Al anode surface, a natural physical barrier to the plating of hydrated aluminum ions, is a key factor in the decomposition of the aqueous electrolyte and the severe hydrogen precipitation reaction. To circumvent the obnoxious Al anode, a proof-of-concept of an anode-free AAIB is first proposed, in which Al 2 TiO 5 , as a cathode pre-aluminum additive (Al source), can replenish Al loss by over cycling. The Al-Cu alloy layer, formed by plating Al on the Cu foil surface during the charge process, possesses a reversible electrochemical property and is paired with a polyaniline (cathode) to stimulate the battery to exhibit high initial discharge capacity (175 mAh g -1 ), high power density (≈410 Wh L -1 ) and ultra-long cycle life (4000 cycles) with the capacity retention of ≈60% after 1000 cycles. This work will act as a primer to ignite the enormous prospective researches on the anode-free aqueous Al ion batteries., (© 2024 Wiley‐VCH GmbH.)

Simultaneously achieving high-energy-density and high-power-density is a crucial yet challenging objective in the pursuit of commercialized power batteries. In this study, atomic layer deposition (ALD) is employed combined with a coordinated thermal treatment strategy to construct a densely packed, electron-ion dual conductor (EIC) protective coating on the surface of commercial LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode material, further enhanced by gradient Al doping (Al@EIC-NCM523). The ultra-thin EIC effectively suppresses side reactions, thereby enhancing the stability of the cathode-electrolyte interphase (CEI) at high-voltages. The EIC's dual conduction capability provides a potent driving force for Li + transport at the interface, promoting the formation of rapid ion deintercalation pathways within the Al@EIC-NCM523 bulk phase. Moreover, the strategic gradient doping of Al serves to anchor the atomic spacing of Ni and O within the structure of Al@EIC-NCM523, curbing irreversible phase transitions at high-voltages and preserving the integrity of its layered structure. Remarkably, Al@EIC-NCM523 displays an unprecedented rate capability (114.7 mAh g -1 at 20 C), and a sustained cycling performance (capacity retention of 74.72% after 800 cycles at 10 C) at 4.6 V. These findings demonstrate that the proposed EIC and doping strategy holds a significant promise for developing high-energy-density and high-power-density lithium-ion batteries (LIBs)., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

With the increasing demand for smaller, lighter, and more affordable electromagnetic devices, there is a growing trend toward developing high-power-density transformers and electrical machines. While increasing the operating frequency is a straightforward approach to achieving high power density, it can lead to significant power loss within a limited volume, resulting in excessive temperature rise and device degradation. Therefore, it is crucial to design high-power-density electromagnetic devices that exhibit low power loss and efficient thermal dissipation to address these challenges. Advanced techniques, such as the utilization of novel and advanced electromagnetic materials, hold great promise for overcoming these issues. Specifically, nanocrystalline and amorphous magnetic materials have emerged as highly effective solutions for reducing power loss and increasing efficiency in electromagnetic devices. This paper aims to provide an overview of the application of nanocrystalline and amorphous magnetic materials in transformers and electrical machines, along with key technologies and the major challenges involved.

Aqueous lithium‐ion batteries are normally limited at low temperatures, because of the consequent low conductivity of electrolytes and the sluggish kinetics of electrode materials. Herein, a high‐performance ultra‐low temperature aqueous lithium ion‐bromine battery (ALBB) realized by a tailored functionalized electrolyte (TFE) consisting of lithium bromide and tetrapropylammonium bromide (TPABr) is reported, which can maintain liquid state with high conductivity (1.89 mS cm‐1) at −60 °C. In addition, with the help of excellent bromine‐fixation of TPABr, the high reversible capacity can be provided by the fast redox reaction of Br2/Br‐ couple in the cathode from room temperature (RT) to −60 °C. Moreover, 1,4,5,8‐naphthalenetetracarboxylic dianhydride‐derived polyimide anode can deliver excellent low‐temperature capacity retention as well as enhanced rate capability and reversibility at RT in TFE. As a result, the designed TFE can endow ALBB with high energy densities (98, 64, and 32 Wh kgdry‐1 at RT, −40, and −60 °C, respectively), outstanding power densities (24.6 and 1.2 kW kgdry‐1 at RT and −40 °C, respectively), and superior capacity retentions (94% and 98% after running 1000 cycles at RT and −40 °C, respectively). This work demonstrates a novel strategy to widen the temperature range of aqueous batteries. [ABSTRACT FROM AUTHOR]

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Poor oxygen diffusion at multiphase interfaces in an air cathode suppresses the energy densities of zinc–air batteries (ZABs). Developing effective strategies to tackle the issue is of great significance for overcoming the performance bottleneck. Herein, inspired by the bionics of diving flies, a polytetrafluoroethylene layer was coated on the surfaces of Co3O4 nanosheets (NSs) grown on carbon cloth (CC) to create a hydrophobic surface to enable the formation of more three‐phase reaction interfaces and promoted oxygen diffusion, rendering the hydrophobic‐Co3O4 NSs/CC electrode a higher limiting current density (214 mA cm−2 at 0.3 V) than that (10 mA cm−2) of untreated‐Co3O4 NSs/CC electrode. Consequently, the assembled ZAB employing hydrophobic‐Co3O4 NSs/CC cathode acquired a higher power density (171 mW cm−2) than that (102 mW cm−2) utilizing untreated‐Co3O4 NSs/CC cathode, proving the enhanced interfacial reaction kinetics on air cathode benefiting from the hydrophobization engineering. [ABSTRACT FROM AUTHOR]

To solve theproblems of an insufficient braking moment for the eddy current retarder at high speed, a small braking moment and slow response of the hydraulic retarder at low speed, and a low power density of the existing electromagnetic hydraulic retarder(EHR), a novel radially distributed electromagnetic-hydraulic retarder(R-EHR) was proposed. The R-EHR fully absorbs the advantages of the braking characteristics of hydraulic retarders and eddy current retarders. The cooling fluid is used to realize the braking of the hydraulic part. At the same time, it acts on the heating surfaces to improve the torque of the electromagnetic part. In this paper, finite element models of the flow field and electromagnetic field are established to predict braking performance. The braking performance of the R-EHR is obtained by bench test, the error between the simulation and experimental data is compared, and the experimental data are analyzed. The results show that the proportion of electromagnetic braking torque in the novel R-EHR is more reasonable. The braking torque increased by 26% and the power density increased by 37.5% at 2000 RPM compared to that of the EHR. The R-EHR can control the braking torque only by adjusting the current, thus simplifying the control system. [ABSTRACT FROM AUTHOR]