Power Devices Research Articles

Control Strategy for Power Fluctuation Smoothing at Distribution Network Substations Considering Multiple Types of Adjustment Resources

With the proposal of the dual carbon target, the distributed photovoltaic (PV) industry has rapidly developed in recent years. However, the randomness and volatility of photovoltaic energy can be transmitted to the main grid through distribution network substations, posing challenges to the stable operation of the power system. Therefore, this paper considers tapping into the regulation potential of feeder loads on the distribution network side, as well as distributed energy storage and distributed PV resources, to enhance the grid’s control methods. A power fluctuation smoothing control strategy for substations in distribution networks, accounting for multiple types of regulation resources, is proposed. In the day-ahead stage, traditional voltage regulation devices such as the OLTC (on-load tap changer) and CB (circuit breaker) are pre-dispatched based on source–load forecasts, optimizing the fluctuation range of substation power and the number of device operations. This provides optimal substation power values for day-to-day optimization. During the intraday phase, fast regulation devices such as PV (photovoltaic), SVC (static var compensator), and energy storage systems are coordinated, and an optimization model is established with the goal of reducing power curtailment while closely tracking substation trends. This model quickly calculates the active power regulation and device operations of various adjustable resources, improving the economic efficiency of the distribution network system while achieving power fluctuation smoothing at the substation level. Finally, the feasibility and effectiveness of the power fluctuation smoothing control model are verified through simulations on an improved standard distribution system.

Development of GaN-Based, 6.6 kW, 450 V, Bi-Directional On-Board Charger with Integrated 1 kW, 12 V Auxiliary DC-DC Converter with High Power Density

Automotive-grade GaN power switches have recently been made available in the market from a growing number of semiconductor suppliers. The exploitation of this technology enables the development of very efficient power converters operating at much higher switching frequencies with respect to components implemented with silicon power devices. Thus, a new generation of automotive power components with an increased power density is expected to replace silicon-based products in the development of higher-performance electric and hybrid vehicles. 650 V GaN-on-silicon power switches are particularly suitable for the development of 3–7 kW on-board battery chargers (OBCs) for electric cars and motorcycles with a 400 V nominal voltage battery pack. This paper describes the design and implementation of a 6.6 kW OBC for electric vehicles using automotive-grade, 650 V, 25 mΩ, discrete GaN switches. The OBC allows bi-directional power flow, since it is composed of a bridgeless, interleaved, totem-pole PFC AC/DC active front end, followed by a dual active bridge (DAB) DC-DC converter. The OBC can operate from a single-phase 90–264 Vrms AC grid to a 200–450 V high-voltage (HV) battery and also integrates an auxiliary 1 kW DC-DC converter to connect the HV battery to the 12 V battery of the vehicle. The auxiliary DC-DC converter is a center-tapped phase-shifted full-bridge (PSFB) converter with synchronous rectification. At the low-voltage side of the auxiliary converter, 100 V GaN power switches are used. The entire OBC is liquid-cooled. The first prototype of the OBC exhibited a 96% efficiency and 2.2 kW/L power density (including the cooling system) at a 60 °C ambient temperature.

Powerful Devices: Prayer and the Political Praxis of Spiritual Warfare by Abimbola Adunni Adelakun (review)

Powerful Devices: Prayer and the Political Praxis of Spiritual Warfare by Abimbola Adunni Adelakun (review)

Coordinated PWM-Based Active Thermal Control for Power Semiconductor Devices in Parallel Grid-Tied Inverters

Coordinated PWM-Based Active Thermal Control for Power Semiconductor Devices in Parallel Grid-Tied Inverters

Performance Evaluation of Solar PV Integrated with Custom Power Device under Various Load Conditions

The non-linear properties and rapid switching of power electronic equipment are the primary causes of power quality issues in power systems, particularly in the power distribution systems. The widespread use of delicate equipment, which continuously pollutes the environment, is making power quality problems worse. The increasing integration of renewable energy sources into the generation mix and the decarburization of the economy have created new challenges for smart grid technology, requiring creative solutions such as energy storage systems and smart transformers. This article describes a solar photovoltaic integrated unified power quality conditioner (UPQC) that uses a deep learning method based on neural networks and a novel compensating technique. Here, two Deep Neural Network algorithms are used, one in the solar PV system to obtain the maximum power under various irradiance situations, and the other to manage the UPQC under various load conditions. When compared to the conventional UPQC based on PQ Theory, DNN-UPQC produces superior results in terms of reducing total harmonic distortion. This iterative strategy, which is focused on soft computing, provides faster convergence to the target condition while maintaining the updating weight within a predetermined limit. PV-based UPQC has been connected individually to reduce voltage sag, swell, and unbalance in variable load conditions. The system's dynamic and steady state performance are assessed by modelling it with a MATLAB-Simulink in different load condition.

Advancing energy storage capabilities in 0.7BNST(1-x)-0.3BLMNx lead-free dielectric ceramic materials

Lead-free ferroelectric ceramics with a composition of 0.7(Bi0.5Na0.5)0.7Sr0.3Ti(1-x)O3-0.3Ba0.94La0.04(Mg1/3Nb2/3)xO3 (abbreviated as 0.7BNST(1-x)-0.3BL(MN)x, 0 ≤ x ≤ 0.12) were prepared using solid-phase sintering method, involving co-substituting at A and B sites. High recoverable energy density (Wrec) of 3.54 J/cm3 and energy efficiency (η) 85.49% are achieved at an electric field of 270 kV/cm. Furthermore, these ceramics exhibited excellent temperature and cycle stability at 120 kV/cm (within 25 °C–150 °C, Wrec fluctuation range <14 %; under 1∼106 cycles, the Wrec fluctuation range <5 %). In terms of dielectric performance, they exhibited a high dielectric constant (εr∼4540), an extremely low dielectric loss tanδ of <0.04 (30 °C–300 °C), and good temperature stability with Δε/ε150 °C ≤ ±15 % (−19.5 °C–233.4 °C). During the charging and discharging process, these ceramics demonstrated a high energy density (Wd) of 1.2 J/cm3, a power density (PD) of 61.7 MW/cm3, and an extremely short discharge time (t0.9) of approximately ∼0.11 μs＀ This study has improved the dielectric energy storage performance of BNT-based lead-free piezoelectric ceramics, making them suitable for use in pulse power devices.

Optimization of microstructure to improve Si3N4 ceramics with thermal conductivity and mechanical properties: effect of Si and α-Si3N4 powder composition

The heat dissipation capacity and mechanical reliability of silicon nitride (Si3N4) ceramic substrates determine the service life of power devices. In this work, a two-step sintering method was designed to produce Si3N4 ceramics with excellent performance using Si and α-Si3N4 powders with different ratios as raw materials. The nitridation mechanism and the microstructural evolution mechanism were clarified. The in-situ-generated β-Si3N4 seeds regulated the microstructure of the post-sintered Si3N4 ceramics. The introduction of Si powder reduced the content of oxygen impurities and regulated the microstructure of Si3N4 ceramics, thereby improving thermal conductivity while maintaining excellent mechanical properties. When the mass ratio of Si powder nitridation to α-Si3N4 was 0.75, its thermal conductivity was 120W·m-1·K-1, fracture toughness was 11.92±0.36MPa·m1/2, and bending strength was 712±20.6MPa. This study provides a strategy to reduce the introduction of oxygen impurities while optimizing the microstructure to prepare Si3N4 ceramics with excellent performance.

Research on avalanche tolerance test method for power devices based on avalanche energy equivalence

Research on avalanche tolerance test method for power devices based on avalanche energy equivalence

Enhanced flow boiling by manipulating two-phase flow in Tesla channel heat sink using HFE-7100

Flow boiling of dielectric fluids in copper microchannel heat sinks is highly desirable for cooling large-sized insulated gate bipolar transistor (IGBT) power electronic modules. However, dielectric fluids present challenges in flow boiling because of their unfavorable thermophysical properties. These factors make it difficult to enhance critical heat flux (CHF) without precooling. To address this, we developed a large copper heat sink (10 cm × 5 cm) with Tesla microchannels designed to suppress vapor backflow and promote intense fluid mixing. The microchannels have a high length to hydrodynamic diameter ratio of approximately 220, significantly higher than those in previous studies. Flow boiling experiments using HFE-7100 were conducted for both Tesla and plain-wall microchannels. Tesla channels demonstrated a 26.2 % increase in CHF and a 120 % improvement in heat transfer coefficient (HTC). These enhancements are attributed to the vapor backflow suppression and improved fluid mixing. Moreover, the standard deviation of wall temperature in plain-wall microchannels was 10 times higher than in Tesla channels, highlighting the effectiveness of the periodic Tesla valves in reducing two-phase flow instabilities. Flow pattern visualization was conducted to further understand the mechanism behind vapor regulation, clarifying the role of Tesla valves in controlling vapor backflow. This study demonstrates the potential of dielectric fluids in Tesla microchannels for flow boiling applications, offering a promising solution for cooling large electronics.

3D-simulation design of a high current capacity GaN tri-gate power device with integrated parasitic bipolar junction

3D-simulation design of a high current capacity GaN tri-gate power device with integrated parasitic bipolar junction

Incorporating MXene with Redox Carriers on Capacitive Carbon Cloth-Based Freestanding Electrodes for Power Applications

Abstract Battery-like organic materials including quinone-based electrodes with electrochemical activity have been extensively investigated for their use as electrode materials in energy storage devices due to their economic competitiveness and sustainable benefits. However, the intrinsic electrical insulating nature of organic quinones and their electrochemical reactivity limit power capability and stability upon charge/discharge cycling, respectively. Here, we report the preparation of a concentric layered architecture, MXene/Anthraquinone/Carbon Cloth (M/AQ/CC), by physisorption of anthraquinone onto the surface of carbon cloth via non-covalent π–π interactions, followed by dipping in exfoliated MXene suspension. The M/AQ/CC electrode, with a high mass loading (18.2 mg cm-2), delivered a capacity of 46 mAh g-1 (about 1 mAh cm-2 areal capacity or 6 mAh mL-1 volume) at 0.5 A g-1, with good rate performance and an enhanced cyclability over 5k cycles. This simple preparation method can also be applied to incorporate MXene with a series of alternative organic redox carriers on freestanding carbon cloth, including thionin acetate and anthraquinone-2-sulfonate. The improvement in electrochemical performance highlights an efficient approach to store more charges via redox reactions from organic quinones pi-stacked at carbon surfaces, thanks to a protective MXene shield that stabilizes the Faradaic behavior of quinones over repetitive charge-discharge processes. The simplicity and versatility of this method should enable design of many advanced electrode materials based on MXene/quinones/carbon cloth for power devices

Effects of High-Temperature Treatments in Inert Atmosphere on 4H-SiC Substrates and Epitaxial Layers

Silicon carbide is a wide-bandgap semiconductor useful in a new class of power devices in the emerging area of high-temperature and high-voltage electronics. The diffusion of SiC devices is strictly related to the growth of high-quality substrates and epitaxial layers involving high-temperature treatment processing. In this work, we studied the thermal stability of substrates of 4H-SiC in an inert atmosphere in the range 1600–2000 °C. Micro-Raman spectroscopy characterization revealed that the thermal treatments induced inhomogeneity in the wafer surface related to a graphitization process starting from 1650 °C. It was also found that the graphitization influences the epitaxial layer successively grown on the wafer substrate, and in particular, by time-resolved photoluminescence spectroscopy it was found that graphitization-induced defectiveness is responsible for the reduction of the carrier recombination lifetime.

A Survey of Incentive Mechanisms for Federated Learning

Federated learning is a cutting-edge distributed machine learning technique that lowers the possibility of data leaking from centralized uploads by enabling users to cooperatively train models. It not only protects client privacy but also better utilizes decentralized data resources, demonstrating high learning performance. To employ their models in the training process, however, a significant number of clients must be involved, which inexorably uses up the device's resourcescomputational power, communication bandwidth, and energy. Therefore, incentivizing more clients to participate in federated learning is crucial. Typical methods can provide numerical or model-based compensation to ensure they contribute their valuable model resources. This paper provides a brief introduction to federated learning and incentive mechanisms, and surveys related research on federated learning incentives. Specifically, this paper categorizes existing federated learning incentive mechanisms into four technical approaches: Shapley values, Stackelberg games, auctions, and contracts. Finally, the paper discusses some future directions for incentivizing clients in federated learning.

Portable Homemade Magnetic Hyperthermia Apparatus: Preliminary Results.

This study aims to describe and evaluate the performance of a new device for magnetic hyperthermia that can produce an alternating magnetic field with adjustable frequency without the need to change capacitors from the resonant bank, as required by other commercial devices. This innovation, among others, is based on using a capacitator bank that dynamically adjusts the frequency. To validate the novel system, a series of experiments were conducted using commercial magnetic nanoparticles (MNPs) demonstrating the device's effectiveness and allowing us to identify new challenges associated with the design of more powerful devices. A computational model was also used to validate the device and to allow us to determine the best system configuration. The results obtained are consistent with those from other studies using the same MNPs but with magnetic hyperthermia commercial equipment, confirming the good performance of the developed device (e.g., consistent SAR values between 1.37 and 10.80 W/gMNP were obtained, and experiments reaching temperatures above 43 °C were also obtained). This equipment offers additional advantages, including being economical, user-friendly, and portable.

Experimental study of the flow boiling heat transfer characteristics of teardrop-like micro-pin-finned chip surface in semi-open microchannel

Phase change flow boiling heat transfer in microchannel is a very efficient thermal management mode for high-power electronics/devices. However, it is still a challenge to achieve comprehensive enhancement of flow boiling heat transfer performance at low power consumption. Herein, we devised and manufactured a set of teardrop-like micro-pin-finned chip surfaces, demonstrating their exceptional enhancement in flow boiling heat transfer efficiency within semi-open microchannels with negligible pumping energy input. Benefiting from the effective expansion area, the pinning effect and the streamlined bionic structure of the micro-pin-fins, the staggered teardrop-like micro-pin-finned surface (S37) exhibits simultaneous enhancement of critical heat flux (CHF) and heat transfer coefficients (HTC). The CHF and HTC peaks reached 414.1 W/cm² and 42,153.3 W/m²·K, with maximum enhancement ratios of 52.8 % and 78.1 % relative to the smooth surface. A nearly linear improvement in the heat flux (from 93.1 to 414.1 W/cm², enhanced by 447.8 %) is observed within a minimal fluctuation in wall temperatures, not exceeding 10 °C. The semi-open microchannels provide ample space for boiling nucleation bubbles to move efficiently, enhancing heat transfer performance while maintaining a very low pressure drop (≤1.2 kPa) and without increasing power consumption. In situ observation and analysis of the boiling bubble dynamics indicated teardrop-like micro-pin-finned chip promotes the phase change heat exchange process by massive nucleation sites, and effective control of boiling bubbles by pinning effect. These findings not only provide guidance for the rational design of boiling heat transfer-enhanced surfaces and heat sinks, but also point the way to achieving efficient thermal management of power devices.

Cooling high power electronics using dynamic phase change material

Phase change materials (PCMs) offer effective transient cooling due to their high latent heat of fusion and energy density. Unfortunately, PCMs generally have relatively low thermal conductivity, impeding effective heat dissipation from the heat source and limiting their power density. This work uses dynamic PCM (dynPCM) cooling for thermal management of high power electronics. DynPCM cooling uses pressure-enhanced close-contact melting of a PCM. The applied pressure causes liquid PCM to be pumped away from the heat transfer surface, maintaining a thin melt layer and high heat transfer. Through experimental investigations with a circuit board mounted 2 × 2 array of gallium nitride (GaN) power transistors integrated with heat spreaders of different thicknesses, we evaluate the cooling performance of dynPCM across various device heat dissipation levels (4.4 W/cm² to 46.6 W/cm²) and under both homogeneous and heterogeneous heating conditions. Using paraffin as the PCM, we explore the effects of different pressures (0 Pa, 750 Pa, and 7.5 kPa) on dynPCM cooling effectiveness. DynPCM significantly enhances cooling for electronics operating at high power, achieving over a 50 % reduction in steady-state junction temperature when compared to both traditional air-cooled and hybrid PCM-cooled systems at a 32.4 W/cm² individual GaN device power loss. We developed a reduced-order thermal resistance model to assess heat transfer from the electronic devices through the heat spreader into the dynPCM. The model helps to illustrate the critical role of the heat spreader design and PCM geometry on cooling performance, offering design guidelines for dynPCM thermal management systems. This work highlights the potential of dynPCM as a thermal management strategy for high-power electronic devices, facilitating the advancement of more effective cooling methods for a variety of applications.

Systematic Review of Battery Life Cycle Management: A Framework for European Regulation Compliance

Batteries are fundamental to the sustainable energy transition, playing a key role in both powering devices and storing renewable energy. They are also essential in the shift towards greener automotive solutions. However, battery life cycles face significant environmental challenges, including the harmful impacts of extraction and refining processes and inefficiencies in recycling. Both researchers and policymakers are striving to improve battery technologies through a combination of bottom–up innovations and top–down regulations. This study aims to bridge the gap between scientific advancements and policy frameworks by conducting a Systematic Literature Review of 177 papers. The review identifies innovative solutions to mitigate challenges across the battery life cycle, from production to disposal. A key outcome of this work is the creation of the life cycle management framework, designed to align scientific developments with regulatory strategies, providing an integrated approach to address life cycle challenges. This framework offers a comprehensive tool to guide stakeholders in fostering a sustainable battery ecosystem, contributing to the objectives set by the European Commission’s battery regulation.

Enhanced dielectric breakdown strength and thermal conductivity of silicone gel composites with high-electron-affinity silicon Dioxide/Cationic Polymer/Nano-diamond

In order to address the contradiction that breakdown strength and thermal conductivity of materials are difficult to improve simultaneously, we report a novel calcined silicon dioxide/cationic polymer/nano-diamond (SD*@ND) filler with high electron affinity via self-assembled in-situ polymerization, electrostatic interaction and calcination technique. Subsequently, the calcined SD*@ND fillers are intercalated into the silicone gel to achieve a concurrent enhancement of electrically insulating properties and thermal conductivity of composites. For example, breakdown strength and thermal conductivity of the silicone gel composites with 20 wt% calcined SD*@ND are 17.97 kV/mm and 0.557 W/m·K, respectively. These results are remarkably higher than those (16.77 kV/mm, 0.211 W/m·K) of silicone gel usually used as a commercial packaging material of power devices. Meanwhile, it also shows excellent high-temperature electrically insulating properties. This work provides a scalable approach to developing a novel silicone gel composites with high performance.

Analysis of Key Factors Affecting Case-to-Ambient Thermal Resistance in Thermal Modeling of Power Devices

Analysis of Key Factors Affecting Case-to-Ambient Thermal Resistance in Thermal Modeling of Power Devices

Design and research of high voltage β-Ga2O3/4H-SiC heterojunction LDMOS

Abstract In recent years, gallium oxide (Ga2O3), one of the ultra-wide band-gap semiconductor materials, has been regarded as one of the most promising materials in the field of high-voltage and high-power electronic devices in the future because of its unique electrical properties and low preparation cost. However, it is difficult for β-Ga2O3 materials to form effective P-type doping, so the PN junction is not formed in most of its power devices, which greatly limits the improvement of its voltage resistance. A novel lateral double-diffused metal-oxide-semiconductor field-effect transistor (LDMOS) is proposed to realize a junction β-Ga2O3 power device and improve the voltage resistance performance of β-Ga2O3 power devices. In this device, a β-Ga2O3 power device with a junction is realized by using P-type 4H-SiC to form a PN junction with N-type β-Ga2O3, and the voltage resistance of the β-Ga2O3 power device is improved. Sentaurus TCAD software was used to simulate the device structure and electrical performance. The device is optimized by adjusting the length of the drift zone, drift zone concentration, SiC channel concentration, and gate oxide thickness. Optimized, the device exhibits a positive threshold voltage of 3.42 V, a breakdown voltage of 2203 V, a specific on-resistance of 7.80 mΩ·cm2, and a power figure of merit of 622 MW cm−2. The results show that the heterojunction device is significant for realizing high-performance junction β-Ga2O3 power devices.