High Power Applications Research Articles

A GaN-based SOI plasmonic nanolaser design with high-output power

Abstract Due to its unique optical and electrical properties, gallium nitride (GaN) exhibits great promise for nanolaser cavities. 
These characteristics include high electron mobility, wide bandgap energy, and a high refractive index. Moreover, GaN exhibits remarkable thermal stability, making it appropriate for high-power laser applications. The choice of active medium material can significantly impact the laser's performance, including its wavelength, output power, and efficiency. This work designed and numerically demonstrated a GaN -WG built-in SiO_2 substrate with an input and output Si-waveguide nanolaser. These nanolasers lase multi-output wavelengths in both directions 
(forward and backward) at 1680 and 1750 nm, respectively. The pump power is 800 nm. The GaN- waveguide material, when used in nanolaser cavity design, gives many different advantages like concentration of the Gaussian envelope and improved polarization depending on rate (PDR). Increasing lasing efficiency by 76.6 % in the forward direction and 96.7% in the backward direction. Get a low lasing threshold of approximately 200 μW in the forward direction and 180 μW backward direction. Finally, improved the output laser power in both directions (460 μW and 600 μW) in the forward and backward directions, respectively.

Inverter With Paralleled Modules to Extend Current Capacity and Combat Motor Overvoltage in SiC-Based Adjustable Speed Drives

This article proposes a quasi-three-level (Q3L) PWM-based module-parallel inverter to address two major issues of deploying SiC MOSFETs in high-power cable-fed adjustable speed drives. Firstly, the maximum output power of SiC inverters is limited due to the lack of high current rating SiC devices, which cannot satisfy the demand of high-power applications such as heavy-duty electric vehicles and more electric aeroplanes. The second issue comes from the fast-switching speed of SiC MOSFETs, where power cables act like transmission lines under steep rising/falling voltages (high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> ), with back and forth voltage reflections that result in serious overvoltage oscillations at motor terminals. To address these issues, a SiC module-parallel inverter is adopted with elevated current capacity, where the phase voltage is maintained at the mid-point of a coupled inductor connected to the output nodes of each paralleled half-bridge module. By actively controlling the switching delay between the paralleled half-bridge-legs, Q3L PWM waveforms are generated at the inverter output nodes which can mitigate the motor overvoltage due to the voltage reflections through power cables. An active current control technique is also proposed to facilitate the current balance between the paralleled half-bridge-legs. The proposed Q3L PWM-based module-parallel inverter is experimentally verified using a SiC-based cable-fed motor drive system. The results show that the proposed approach can extend the current capabilities of SiC devices as well as mitigate the motor overvoltage, enabling the adoption of SiC devices in high-power motor drives.

Design and Development of GaN-Based Power Amplifier for Radar Applications

This paper presents a comprehensive overview of Gallium nitride (GaN)-based power amplifier (PA) design for various frequency bands. GaN-based technology has emerged as a promising alternative to traditional silicon-based amplifiers due to its superior performance characteristics, which are discussed in this paper. This paper also discusses the key design parameters and challenges associated with PA design. Various design techniques and topologies for GaN power amplifiers are explored besides addressing theoretical considerations of PA design along with a complete systematic design procedure for L-Band amplifier using the wolfspeed large signal GaN HEMT model. To further demonstrate the useful methodology, the designs of S-band and C-band PAs are also presented. GaN-based devices are very promising candidates for high-power applications. It is widely used in various high-power applications including communication and radar.

An Improved Single-Phase Multiple DC Source Inverter Topology for Distributed Energy System Applications

This work presents an improved structure of a single-phase muti-input multilevel inverter (MIMLI) for distributed energy resources, which is capable of producing a nine-level output in symmetric mode and 21 levels in asymmetrical mode. The topology uses four DC sources and ten switches, with four switches being bidirectional and the remaining unidirectional. The operation of the circuit is analyzed in an asymmetrical mode, and switching signals are accomplished using the Nearest Level Control (NLC) PWM technique. Depending on the value of the DC sources used, the number of levels can vary. In this work, different DC source algorithms were also proposed, and the analysis of the inverter has been carried out considering the algorithms producing the maximum number of levels. The inverter was simulated in MATLAB/Simulink under steady state and dynamic conditions, achieving a 3.89% THD in output. The thermal analysis was conducted using PLECS software 4.1.2 to assess losses and efficiency. A laboratory prototype of the proposed topology was developed and tested, confirming its performance through simulation results and proving it economically viable for medium- and high-power applications.

Designing process and analysis of a new SOI-MESFET structure with enhanced DC and RF characteristics for high-frequency and high-power applications.

This research introduces a new designing process and analysis of an innovative Silicon-on-Insulator Metal-Semiconductor Field-Effect (SOI MESFET) structure that demonstrates improved DC and RF characteristics. The design incorporates several modifications to control and reduce the electric field concentration within the channel. These modifications include relocating the transistor channel to sub-regions near the source and drain, adjusting the position of the gate electrode closer to the source, introducing an aluminum layer beneath the channel, and integrating an oxide layer adjacent to the gate. The results show that the AlOx-MESFET configuration exhibits a remarkable increase of 128% in breakdown voltage and 156% in peak power. Furthermore, due to enhanced conductivity and a significant reduction in gate-drain capacitance, there is a notable improvement of 53% in the cut-off frequency and a 28% increase in the maximum oscillation frequency. Additionally, the current gain experiences a boost of 15%. The improved breakdown voltage and peak power make it suitable for applications requiring robust performance under high voltage and power conditions. The increased maximum oscillation frequency and cut-off frequency make it ideal for high-frequency applications where fast signal processing is crucial. Moreover, the enhanced current gain ensures efficient amplification of signals. The introduced SOI MESFET structure with its modifications offers significant improvements in various performance metrics. It provides high oscillation frequency, better breakdown voltage and good cut-off frequency, and current gain compared to the traditional designs. These enhancements make it a highly desirable choice for applications that demand high-frequency and high-power capabilities.

NiGa2O4 interfacial layers in NiO/Ga2O3 heterojunction diodes at high temperature

NiO/Ga2O3 heterojunction diodes have attracted attention for high-power applications, but their high temperature performance and reliability remain underexplored. Here, we report the time evolution of the electrical properties in the widely studied p-NiO/n-Ga2O3 heterojunction diodes and formation of NiGa2O4 interfacial layers at high temperatures. Results of our thermal cycling experiment show an initial leakage current increase which stabilizes after sustained thermal load, due to reactions at the NiO–Ga2O3 interface. High-resolution TEM microstructure analysis of the devices after thermal cycling indicates that the NiO–Ga2O3 interface forms a ternary compound at high temperatures, and thermodynamic calculations suggest the formation of the spinel NiGa2O4 layer between NiO and Ga2O3. First-principles defect calculations find that NiGa2O4 shows low p-type intrinsic doping and hence can serve to limit electric field crowding at the interface. Vertical NiO/Ga2O3 diodes with intentionally grown ∼5 nm thin spinel-type NiGa2O4 interfacial layers show an excellent device ON/OFF ratio of &amp;gt;1010 (± 3 V), VON of ∼1.9 V, and increased breakdown voltage of ∼1.2 kV for an initial unoptimized 300 μm diameter device. These p–n heterojunction diodes are promising for high-voltage, high temperature applications.

Energy Storage Systems: Technologies and High-Power Applications

Energy storage systems are essential in modern energy infrastructure, addressing efficiency, power quality, and reliability challenges in DC/AC power systems. Recognized for their indispensable role in ensuring grid stability and seamless integration with renewable energy sources. These storage systems prove crucial for aircraft, shipboard systems, and electric vehicles, addressing peak load demands economically while enhancing overall system reliability and efficiency. Recent advancements and research have focused on high-power storage technologies, including supercapacitors, superconducting magnetic energy storage, and flywheels, characterized by high-power density and rapid response, ideally suited for applications requiring rapid charging and discharging. Hybrid energy storage systems and multiple energy storage devices represent enhanced flexibility and resilience, making them increasingly attractive for diverse applications, including critical loads. This paper provides a comprehensive overview of recent technological advancements in high-power storage devices, including lithium-ion batteries, recognized for their high energy density. In addition, a summary of hybrid energy storage system applications in microgrids and scenarios involving critical and pulse loads is provided. The research further discusses power, energy, cost, life, and performance technologies.

Spacer engineering on multi-channel FinFET for advanced wireless applications

Wireless applications require a low power technology that enables DC/analog/RF functions on the same chip. It is well established fact that Multi-channel FinFET (Multifin) enhances the DC/analog/RF performance of the FET. The proposed design with spacer dielectric ensures reduced OFF current (IOFF), better subthreshold performance and improved ON current (ION) towards high performance and low power applications. Along with single-k spacer a dual-k spacer combination of (Air + Si3N4) called hybrid spacer (low-k towards gate and high-k near source/drain) is studied for the first time towards DC/analog/RF and linearity metrics of Multifin FET. The Air spacer shows extravagant performance towards RF domain and HfO2 shows better for DC and analog perspective. With Air spacer dielectric the Multifin FET exhibits terahertz (THz) frequency ranges and ensures high frequency applications. The linearity and harmonic distortion metrics towards wireless communication applications with various spacer dielectric is also analysed. The hybrid spacer shows better linearity and harmonic distortion performance along with Air and shows a strong contender towards RF applications. Moreover, the reduced capacitances ensure hybrid spacer is potential towards driving circuit applications at advanced nodes.

Simulating the charging mechanism of a realistic nanoporous carbon-based supercapacitor using a fully polarizable model

Nanoporous carbon-based supercapacitors are established energy storage devices, that complement Li-ion batteries in high-power applications. So far, the study of these systems through simulations required drastic simplification of the electrolyte and/or of the electrode. In this work, we use state-of-the-art constant potential classical molecular dynamics simulations, where both the electrode and the electrolyte are polarizable, to study complex carbide-derived carbons with 1-ethyl-3-methylimidazolium bis(trifluoromethane)sulfonyl imide ionic liquid electrolyte. We show that using this set-up allows to obtain integral capacitances (i.e. the main property to characterize supercapacitors) in quantitative agreement with experiments. The simulations, performed in a range of applied potentials of 1V to 4V, then provide microscopic details on the charging mechanism, revealing that it is not symmetrical between the positive and negative electrodes. A pure exchange of ions is observed on the positive electrode, while an ion exchange combined with cation adsorption takes place on the negative one. Our work shows that accounting for the coupling of electrode and electrolyte polarization improves the accuracy of the results, opening the way toward a more quantitative comparison with experiments.

All-fiber 3 kW LP02 laser output based on long-period fiber grating for precise welding

An innovative all-fiber mode converter specifically designed for high-power fiber lasers is introduced. The mode converter relies on the coupling theory of long-period fiber gratings (LPFGs) and involves the fabrication of a LPFG, where the performance is meticulously studied by examining various fabrication parameters. The LPFG is integrated into a high-power fiber laser system to achieve efficient conversion from the LP01 mode to the LP02 mode with a conversion ratio of 90 % and a low transmission loss of only 0.088 dB. Under a 3.03 kW laser output, the LP02 fiber laser exhibits a remarkable laser-to-raman peak intensity ratio, which is 15.98 dB higher than that of the signal-mode fiber laser. Furthermore, during the welding process of a thick aluminum plate, the LP02 fiber laser demonstrates a significant increase of 1.2 times in the depth of the weld pool morphology compared to the signal-mode fiber laser, particularly evident when operating at a laser welding head speed of 100 mm/s. The mode converter with LPFG exhibits lower insertion loss, enhanced power-handling capacity, making it ideal for diverse high-power fiber laser applications with promising practical prospects.

Frequency tuning and automatic frequency tracking of shunted piezoelectric transducers

Piezoelectric ultrasonic transducers, vital in medical devices and aerospace, often face challenges like resonant frequency shifts and impedance variations affecting their operational efficiency. This paper introduces a shunted piezoelectric transducer which could tune itself by digitally programmable inductance. A transformer and inductance-capacitance matching network ensures enhanced compatibility and impedance management. Proposing a fuzzy PI-based phase control method achieves resonant frequency tracking, synchronizing operational frequency with the transducer. In contrast to traditional methods, our approach enables faster and more precise fine-tuning, detecting and rectifying real-world deviations for optimal performance. A comprehensive experimental validation, based on fundamental knowledge analysis, confirms the feasibility and superiority of our proposed method, and the commonly encountered issues of resonance frequency deviation and impedance variation in high-power piezoelectric transducer applications can be effectively mitigated.

Rapid Detection and Elimination of Subsurface Mechanical Damage for Improving Laser-Induced Damage Performance of Fused Silica

The fabrication of SSD-free fused silica optics is a crucial objective for high-power laser applications. To treat the surface of polished fused silica, a combination of RIE/RIBE and deep-controlled etch (DCE) techniques are typically employed. Currently, it is important to consider and study the ideal etching depth and precision while using combined etching techniques to remove the identified SSD. Herein, we present a novel approach to identify the distribution of SSD in fused silica, which corresponds to a specific grinding/polishing process condition. Our method involves using a mobile RIBE to perform cone cutting and remove material from the polished fused silica surface. Afterward, we etch the optical element’s surface with HF to visualize the subsurface cracks and understand their relationship with the RIBE depth. Through a systematic investigation of the combined etching technique, we establish a correlation between the depth of RIBE and DCE and the performance of laser damage. The combined etching technique can be implemented as a dependable approach to treat the surface/subsurface defects in fused silica and has the potential to improve laser damage resistance significantly.

Enhanced efficiency of deep ultraviolet light-emitting diodes utilizing full-coverage Al reflector and highly reflective Ni/Rh p-electrode

Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.

A new method for improving the solar photovoltaic unit efficiency through neem oil as coolant medium for high power applications—an experimental investigation

AbstractThe utilization of electric energy is rising in the technological world. Solar PV (photovoltaic) cells convert sunlight into electricity, and sunlight radiation also has heat, reducing the panel's efficiency. The heat should control the limited value or otherwise reduce the panel's performance so that heat is moved to the cooling medium, thus maintaining the heat within the functioning limit. The proposed method is explained by the probability of cooling the monocrystalline and polycrystalline structures used as neem oil through an integrated oil container fitted into the unit's backside—the neem oil acts as phase-changing material (PCM). The solar PV rear side neem oil absorbs the heat of the solar PV panel. The neem oil is not filled in the backside tank completely for the reason that the oil needed some breathing gap. The breathing gap of PCM is to enhance the heat-withstand efficiency. The backside neem oil is replaced every 30 min. As an outcome, the front side of solar PV heat is reduced. Neem oil has not polluted the environment and is thus also used to exchange noxious mineral oils. The neem oil moved from the depository tank to the backside of the unit and together into an additional depositor tank, thus being able to be reused. The proposed method is investigated, and functioning comparison occurs in different PV types, such as monocrystalline and polycrystalline modules, with various kinds of edible oil. Thus, the critical outcomes of the monocrystalline and polycrystalline PV panels are to decrease the panel temperature by 2.29% and 4.34%, respectively, and enhance the efficiency of the PV panels by 15.0% and 17.8%, respectively.

Electron mobility enhancement by electric field engineering of AlN/GaN/AlN quantum-well HEMTs on single-crystal AlN substrates

To enhance the electron mobility in quantum-well high-electron-mobility transistors (QW HEMTs), we investigate the transport properties in AlN/GaN/AlN heterostructures on Al-polar single-crystal AlN substrates. Theoretical modeling combined with experiment shows that interface roughness scattering due to high electric field in the quantum well limits mobility. Increasing the width of the quantum well to its relaxed form reduces the internal electric field and scattering, resulting in a binary QW HEMT with a high two-dimensional electron gas (2DEG) density of 3.68×1013 cm–2, a mobility of 823 cm2/Vs, and a record-low room temperature (RT) sheet resistance of 206 Ω/□. Further reduction of the quantum well electric field yields a 2DEG density of 2.53×1013 cm–2 and RT mobility &amp;gt; 1000 cm2/V s. These findings will enable future developments in high-voltage and high-power microwave applications on the ultrawide bandgap AlN substrate platform.

From macro to micro: Biomass-derived advanced carbon microtube assembly for sodium-ion batteries

Developing high-rate anode materials for sodium-ion batteries is important to fulfill the requirement of high-power energy storage applications. Amorphous carbon micro-tubes (CMTs) are favorable for fast Na-ion storage, for the open carbon framework provides sufficient electrode/electrolyte contact and the one-dimensional skeleton offers fast electron and ion diffusion pathways. Herein, N, Fe co-doped carbon micron-tubes (NF-CMTs) were synthesized for the high-rate anode by using bulk biomass as the precursor. The transformation from the macro-sized biomass to the micro-sized carbon tubes was endowed by pyrolysis using N and Fe as catalysts. The open carbon frameworks enable capacitive-controlled capacity contribution, while its N-Fe defects offer multiple active sites for fast Na-ion storage. A high-capacity contribution was demonstrated by the pseudo-capacitive mechanism so that the NF-CMTs performed a superior rate capability of 120 mAh g−1 at 2.0 A g−1. The NF-CMTs with stable micro-tube frameworks exhibited high cycling stability over 1200 cycles, which was much superior to the commercial hard carbon anode. This study provides a cost-effective approach to develop carbon micro-tubes from bulk biomass for high-power SIB anodes.

Research on the Performance Improvement Method for Lithium-Ion Battery in High-Power Application Scenarios

With the development of technology, high-power lithium-ion batteries are increasingly moving towards high-speed discharge, long-term continuous output, instantaneous high-rate discharge, and miniaturization, and are being gradually developed towards the fields of electric tools, port machinery and robotics. Improving the power performance of batteries can be achieved from multiple dimensions, such as electrochemical systems and battery design. In order to improve the power performance of lithium-ion batteries, this paper proposes design methods from the perspective of electrochemical systems, which include increasing the high-rate discharge capacity and low impedance of the battery. This article also studies the preparation of high-power lithium-ion batteries. This article aims to improve the rate performance of batteries by studying high-performance cathode materials, excellent conductive networks, and high-performance electrolytes. This article successfully screened high-performance cathode materials by comparing the effects of different particle sizes of cathode materials on electrode conductivity and battery internal resistance. By comparing the effects of electrolyte additives under pulse cycling, high-quality electrolyte additive materials were selected. By comparing the effects of different types, contents, and ratios of conductive agents on electrode conductivity, battery internal resistance, high-quality conductive agents, and appropriate ratios were selected. Finally, a 10 Ah cylindrical high-power lithium-ion battery with a specific energy of 110 Wh/kg, pulse discharge specific power of 11.3 kW/kg, an AC internal resistance of ≤0.7 m Ω, a 10C full capacity discharge cycle of over 1700, a 30C full capacity discharge cycle of over 500, and a continuous discharge capacity of 10C–30C, and a pulse discharge capacity of over 100C was prepared.

Multilevel Inverter with Enhanced THD Value used in Grid Connected Applications

In this work, the relationships among pulse width modulation (PWM), sinusoidal pulse width modulation (SPWM), and space-vector pulse width modulation (SVPWM) for three-phase inverters will be analyzed to better comprehend their differences. detailed comparison of the three modulation schemes under study’s Total Harmonic Distortion (THD). High-power applications are increasingly concentrating on converter technology. This growing importance may be attributed to its improved output waveforms over the 3- carrier-based sinusoidal pulse width modulation (SPWM). To control and modulate multi-level inverters, many techniques are employed. These methods are categorized based on how frequently they switch. The ripple current rating, capacitance value, and voltage balance in the DC bus capacitors are all impacted by the pulse width modulation techniques. It is crucial to select the modulation method based on the current control requirements, as this determines the output voltage waveform’s harmonic content. SVPWM is gradually becoming more and more popular in industries because of its improved dc bus utilization and ease of digital realization. This work examines PWM, Sinusoidal, and SVPWM feeding a load connected to RL. Three different methodologies’ performances are compared as these methods are investigated through simulation with MATLAB/SIMULINK software.

Identifying the charge states of carbon vacancies in 4H-SiC by ab initio metadynamics

4H Silicon carbide (4H-SiC) is widely recognized as a highly promising material for high-voltage and high-power electronic applications due to its exceptional properties. The performance of devices based on 4H-SiC is often weakened by the presence of carbon-related point defects, particularly carbon vacancies (VC). The defects of VC introduce deep-level traps (e.g., Z1/2 and EH6/7) that deteriorate device functionality. Experimental and theoretical studies on VC have led to some conflicting results about the charge states of VC, especially for the charge state ordering of EH6/7. We now employ ab initio metadynamics (META) to systematically investigate configuration space including the direction and magnitude of bond distortion and identify the most stable structures of VC. Eventually, the charge states of VC in 4H-SiC are identified. The Z1 (EH6) and Z2 (EH7) indicate transitions from acceptor (donor) levels of VC, located on the h and k sublattice sites, respectively. Z1 and Z2 demonstrate negative-U ordering, characterized by U values of −0.16 and −0.37 eV, respectively. Conversely, EH6 and EH7 display positive-U ordering, with U values of 0.16 and 0.08 eV, respectively. The current results provide insights into the properties of VC in 4H-SiC, highlighting the effectiveness of META in the exploration of complex potential energy surfaces associated with point defects in solids.

Developing a high‐performing spinel LiMn2O4 cathode material with unique morphology, fast cycling and scaled manufacture

High power application of Li‐battery remains a challenge due to the lack of stable fast‐charging cathode materials. Lithium manganese oxide (LMO) cathode is very promising due to its high operating voltage and fast charging ability; however, the associated Mn‐dissolution is one of the main hindrances to its practical applicability. In this work, we demonstrate for the first time the use of a commercially scalable method through a proprietary Calix flash calcination (CFC) technology to develop high‐performance electrode materials where a novel CXL LMO material was manufactured and tested. CXL LMO|Li metal cell showed a reversible specific capacity of 110 mAh/g with 99% retention after 100 cycles and showed excellent rate performance up to 20C current rate (~20 mA/cm2 current density). CXL LMO|Graphite cell (areal capacity 1 mAh/cm2) was also reported with 86% capacity retention over more than 500 cycles. Cross‐section morphology revealed a unique multi‐layered structure that was retained at the core of the novel LMO material. It obtained lesser Mn dissolution compared to commercial LMO. The scalable synthesis procedure through CFC technology, can be broadly applicable to produce unique electrode morphology as demonstrated here for the CXL LMO representing a promising pathway for electrode manufacturing for high‐power Li‐batteries.