Search Results (716)

This paper presents a high-efficiency wireless power transfer (WPT) architecture employing a resonant inductive coupling to power smart sensor nodes in remote or sealed environments, where conventional power delivery is unfeasible. The system integrates a photovoltaic (PV) energy source with a step-down DC-DC converter based on the LM2596 buck regulator to adjust the voltage from the PV. The proposed conditioned power system supplies the entire electronic circuit consisting of a PWM modulator based on an NE555, which drives an IR2110 gate driver connected to a Class D power amplifier. The amplifier excites a pair of high-Q resonant coils designed for mid-range inductive coupling. On the receiver side, the inductively coupled AC signal is rectified and regulated through an AC-DC conversion stage to charge a secondary energy storage unit. The design eliminates the need for physical electrical connections, ensuring efficient, contactless energy transfer. The proposed system operates at a resonant frequency of 24.46 kHz and achieves up to 80% transmission efficiency at a distance of 113 mm. The receiver provides a regulated DC output between 4.80 V and 4.97 V, sufficient to power low-consumption smart sensors. Full article

To address the issue of low efficiency in recovering low-frequency vibration energy during vehicle operation, this paper proposes a piezoelectric energy capture harvester based on wheel vibration. The device employs a parallel configuration of dual cantilever beam piezoelectric transducers in its mechanical structure, with additional mass blocks to optimize its resonant characteristics in the low-frequency range. A synchronous switch energy harvesting circuit was designed. By actively synchronizing the switch with the peak output voltage of the piezoelectric element, it effectively circumvents the turn-on voltage threshold limitations of diodes in bridge rectifier circuits, thereby enhancing energy conversion efficiency. A dynamic model of this device was established, and multiphysics simulation analysis was conducted using COMSOL-Multiphysics to investigate the modal characteristics, stress distribution, and output performance of the energy harvester. This revealed the influence of the piezoelectric vibrator’s thickness ratio and the mass block’s weight on its power generation capabilities. Experimental results indicate that under 20 Hz, 12 V sinusoidal excitation, the system achieves an average output power of 3.019 mW with an average open-circuit voltage reaching 16.70 V. Under simulated road test conditions at 70 km/h, the output voltage remained stable at 6.86 V, validating its feasibility in real-world applications. This study presents an efficient and reliable solution for self-powering in-vehicle wireless sensors and low-power electronic devices through mechatronic co-design. Full article

Recently, the installed generation capacity of wind energy has expanded significantly, and the doubly fed induction generator (DFIG) has gained a prominent position amongst wind generators owing to its superior performance. It is extremely vital to enhance the low-voltage ride-through (LVRT) capability for the wind turbine DFIG system because the DFIG is very sensitive to faults in the electrical grid. The major concept of LVRT is to keep the DFIG connected to the electrical grid in the case of an occurrence of grid voltage sags. The currents of rotor and DC-bus voltage rise during voltage dips, resulting in damage to the power electronic converters and the windings of the rotor. There are many protection approaches that deal with LVRT capability for the wind turbine DFIG system. A popular approach for DFIG protection is the crowbar technique. The resistance of the crowbar must be precisely chosen owing to its impact on both the currents of the rotor and DC-bus voltage, while also ensuring that the rotor speed does not exceed its maximum limit. Therefore, this paper aims to obtain the optimal values of crowbar resistance to minimize the crowbar energy losses and ensure stable DFIG operation during grid voltage dips. A recent optimization technique, the Starfish Optimization (SFO) algorithm, was used for cropping the optimal crowbar resistance for improving LVRT capability. To validate the accuracy of the results, the SFO results were compared to the well-known optimization algorithm, particle swarm optimizer (PSO). The performance of the wind turbine DFIG system was investigated by using Matlab/Simulink at a rated wind speed of 13 m/s. The results demonstrated that the increases in DC-link voltage and rotor speed were reduced by 42.5% and 45.8%, respectively. Full article

Gallium nitride (GaN)-based high electron mobility transistors (HEMTs) are pivotal for next-generation power-switching applications, but their reliability under high electric fields remains constrained by lattice mismatches and high dislocation densities in heterogeneous substrates. Herein, we systematically investigate the electrical performance and reliability of GaN-on-GaN HEMTs in comparison to conventional GaN-on-SiC HEMTs via DC characterization, reverse gate step stress, off-state drain step stress, and on-state electrical stress tests. Notably, the homogeneous epitaxial structure of GaN-on-GaN devices reduces dislocation density by 83.3% and minimizes initial tensile stress, which is obtained through HRXRD and Raman spectroscopy. The GaN-on-GaN HEMTs exhibit a record BFOM of 950 MW/cm², enabled by a low specific on-resistance (R_ON-SP) of 0.6 mΩ·cm² and a high breakdown voltage (BV) of 755 V. They withstand gate voltages up to −200 V and drain voltages beyond 200 V without significant degradation, whereas GaN-on-SiC HEMTs fail at −95 V (reverse gate stress) and 150 V (off-state drain stress). The reduced dislocation density suppresses leakage channels and defect-induced degradation, as confirmed by post-stress Schottky/transfer characteristics and Frenkel–Poole emission analysis. These findings establish GaN-on-GaN technology as a transformative solution for power electronics, offering a unique combination of high efficiency and long-term stability for demanding high-voltage applications. Full article

Power semiconductor devices are fundamental components in modern electronic power conversion. In applications demanding high power density and efficiency, the choice between silicon (Si) IGBTs and Silicon Carbide (SiC) MOSFETs is critical. SiC MOSFETs, owing to their high critical electric field, superior thermal conductivity, wide band gap, and low power loss, realize significant performance improvements and compact design. This work presents a comprehensive, simulation-driven comparative investigation under identical setups, evaluating both technologies across various parameters. The effects of temperature variations on gate-source threshold voltage drift, current slew rate, device stress, and energy dissipation during switching transitions are evaluated. Furthermore, the characteristic switching behavior when the DC-bus voltage, gate resistance, and load current are varied is investigated. This study addresses a current scarcity of systematic investigation by presenting a comprehensive comparative evaluation of switching losses and efficiency across varied operating conditions, providing validated conclusions for the design of advanced WBG converters. The results demonstrate that SiC exhibits lower losses and faster switching speeds than Si IGBTs, with minimal temperature-dependent loss variations, unlike Si devices, whose losses rise significantly with temperature. Si shows distinct tail currents during turn-off, absent in SiC devices. A conclusive comparative evaluation of switching energy losses under varied operating conditions demonstrates that SiC devices can effectively retrofit Si counterparts for fast, low-loss, high-efficiency applications. Full article

The results of practical considerations on the issue of conditioning and storing energy obtained from generally available electromagnetic field sources (e.g., commonly used telecommunication systems and RFID radio frequency identification systems) or other potential areas of energy harvesting have been presented in this paper. Due to the low efficiency of this type of alternative power source for electronic microsystems, it is necessary to properly process the obtained energy in order to achieve parameters suitable for powering subsequent elements of the powered system (supply voltage, internal resistance of the source, limitations resulting from the permissible parameters of the components used, etc.) and its effective storage. This paper analyses the use of increasingly available and technologically advanced supercapacitors as the main energy storage device. These are electronic components that fill the gap between commonly known and widely used capacitors and more complex and expensive battery systems that require complicated systems to support the charging and discharging of such storage devices. However, they require consideration of their dynamic characteristics in terms of the charging and energy storage process. The properties of such components were investigated, the requirements and application limitations as a battery were determined, and the results of tests of selected supercapacitors were analysed. Based on the obtained data, several concepts for energy conditioning systems were presented, enabling the practical use of the advantages of supercapacitors as the main energy storage device, for example, an electromagnetic field energy harvester system from an RFID system. Full article

This review investigates how cell form factors (cylindrical, prismatic, and pouch) and electrode architecture (jelly-roll, stacked, and blade) influence the performance, safety, and manufacturability of lithium-ion batteries (LIBs) across the main commercial chemistries LiFePO₄ (LFP), Li (NiMnCo)O₂ (NMC), LiNiCoAlO₂ (NCA), and LiCoO₂ (LCO). Literature, OEM datasheets, and teardown analyses published between 2015 and 2025 were examined to map the interdependence among geometry, electrode design, and electrochemical behavior. The comparison shows trade-offs among gravimetric and volumetric energy density, thermal runaway tolerance, cycle lifespan, and cell-to-pack integration efficiency. LFP, despite its lower nominal voltage, offers superior thermal stability and a longer cycle life, making it suitable for both prismatic and blade configurations in EVs and stationary storage applications. NMC and NCA chemistries achieve higher specific energy and power by using jelly-roll architectures that are best suited for tabless or multi-tab current collection, enhancing uniform current distribution and manufacturability. Pouch cells provide high energy-to-weight ratios and flexible packaging for compact modules, though they require precise mechanical compression. LCO remains confined to small electronics owing to safety and cost limitations. Although LFP’s safety and affordability make it dominant in cost-sensitive applications, its low voltage and energy density limit broader adoption. LiMnFePO₄ (LMFP) cathodes offer a pathway to enhance voltage and energy while retaining cycle life and cost efficiency; however, their optimization across various form factors and electrode architecture remains underexplored. This study establishes an application-driven framework linking form factors and electrode design to guide the design and optimization of next-generation lithium-ion battery systems. Full article

This study demonstrates the fabrication of high-performance p-Cu₂O/n-β-Ga₂O₃ heterojunction barrier Schottky (JBS) diodes using copper as a low-work-function anode metal. By optimizing the Cu₂O spacing to 4 μm, the device achieves a turn-on voltage of 0.78 V, a breakdown voltage of 1700 V, and a specific on-resistance of 5.91 mΩ·cm², yielding a power figure of merit of 0.49 GW/cm². The JBS diode also exhibits stable electrical characteristics across the temperature range of 300–425 K. Under a 200 V reverse stress for 5000 s, the JBS diode shows only a 4.16% degradation in turn-on voltage and a 1.15-fold increase in dynamic specific on-resistance variation, highlighting its excellent resistance to stress-induced degradation. These results indicate that Cu₂O/Ga₂O₃ JBS diodes are promising candidates for next-generation high-efficiency and high-voltage power electronic applications. Full article

As the penetration of distributed energy resources (DERs) continues to increase, there is conjecture concerning the power quality implications of the inverters used to interface these DERs with low-voltage (LV) electricity supply networks. As a power electronics converter, inverters are a known source of harmonic emissions. Using a combination of large-scale field measurements, laboratory evaluations of inverter performance, and power system modelling, this study applies an empirical data-driven approach to investigate the impact of small-scale solar PV inverters on LV harmonic distortion magnitudes. This multi-facetted approach, involving field data analysis, laboratory assessments of inverter performance, and power system simulation to evaluate the impact of small-scale DER on harmonic distortion in LV networks, is novel in comparison to other studies, which only utilise one or two of the analysis methods of simulation, laboratory evaluation, or analysis of field measurements but not all three. The analysis of field measurement data collected over the past decade does not indicate any significant changes in harmonic distortion magnitudes that can be attributed to the increasing penetration of DERs. Power system modelling, which incorporates data obtained from laboratory inverter performance evaluations, indicates that, even at very high levels of penetration, the harmonic current emissions from solar PV inverters are only sufficient to add modest levels of harmonic distortion to LV networks, a 0.25% increase in THD for 40% penetration and a 0.62% increase in THD for 100% penetration, providing an explanation for the findings of the field data analysis. Full article

This paper presents the electrical characterization of the on-resistance (R_ON) of on-wafer 100 V p-GaN power High-Electron-Mobility Transistors (HEMTs). This study assesses device degradation in the context of a monolithically integrated half-bridge circuit, considering both Low-Side (LS) and High-Side (HS) configurations. Since on-wafer samples have been characterized, a custom experimental setup was developed to emulate stress conditions experienced by the devices in the half-bridge circuit. A periodic signal (T = 10 µs, T_ON = 2 µs) switching from the OFF to the ON state was applied for a cumulative duration of 1000 s. Different OFF-state stress conditions were applied by varying the gate-source OFF voltage (V_GS,OFF) between 0 V and −10 V. The on-resistance exhibited a positive drift over time for devices in either the LS or the HS configuration, with the latter showing a more pronounced degradation. Measurements at higher temperatures (up to 90 °C) were carried out to characterize the dynamics of the physical mechanism behind the degradation effects. We identified hole emission from C-related acceptor traps in the buffer as the main mechanism for the observed degradation, which is present in both the HS and the LS configurations. The additional degradation observed in the HS case was attributed to the back-gating effect, stemming from the non-null body-to-source voltage. Furthermore, we found that a more negative V_GS,OFF further increases R_ON degradation, likely related to the higher electric field near the gate contact, which enhances hole emission from C-related acceptor traps. Full article

This work demonstrates for the first time a cost-effective modification of stainless-steel electrodes with an Fe³⁺ precursor via the deep-and-dry method (DDM) at processing temperatures between 20 °C and 80 °C, enabling their simultaneous applicability for both OER and HER in zero-gap electrolyzers. The approach offers a durable and economical alternative to conventional nickel-based electrodes. Morphological and compositional analyses by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) demonstrated a pronounced temperature-dependent evolution of surface features. At 20 °C, the coatings exhibited high porosity and incomplete coverage, whereas treatment at 60 °C yielded a compact, uniform, and continuous layer with suppressed Fe/Ni exposure and enhanced oxygen incorporation. Electrochemical characterization in 25% KOH by cyclic voltammetry and polarization measurements confirmed reversible redox behavior and comparable electrochemically active surface areas across all samples, with the 60 °C electrodes achieving the highest catalytic activity. In electrolysis cell tests (zero gap), the optimized electrodes delivered low cell voltages, current densities up to 1.35 A cm⁻², and power outputs approaching 3.5 W cm⁻². These results establish processing temperature as a decisive factor for tailoring the morphology, composition, and performance of DDM-fabricated electrodes, underscoring the promise of 60 °C-treated electrodes for efficient hydrogen production. Full article

The development of Micro-electro-magnetic Vibration Energy Harvesters (MEMVEHs) plays a crucial role in advancing self-powered nanophotonic, nanoelectronic, and nanosensor systems. As energy autonomy becomes critical for miniaturized devices, MEMVEHs offer a sustainable power source for low-power nanodevices operating in wireless sensor networks, wearable electronics, and biomedical implants. This study provides a comparative assessment of MEMVEH technologies and evaluates their integration potential within next-generation nanoscale systems, enabling enhanced performance, longevity, and energy efficiency of emerging nanotechnologies. Electromagnetic vibration energy harvesters (EMEHs) based on microelectromechanical system (MEMS) technology are promising solutions for powering small-scale, autonomous electronic devices. In this study, two electromagnetic vibration energy harvesters based on microelectromechanical (MEMS) technology are presented. Two models with distinct vibration structures were designed and fabricated. A permanent magnet is connected to a silicon vibration structure (resonator) and a tiny wire-wound coil as part of the energy harvester. The coil has a total volume of roughly 0.8 cm³. Two energy harvesters with various resonators are tested and compared. Model A’s maximum load voltage is 163 mV, whereas Model B’s is 208 mV. A maximum load power of 59.52 μW was produced by Model A at 347 Hz across a 405 Ω load. At 311.4 Hz, Model B produced a maximum load power of 149.13 μW while accelerating by 0.4 g. Model B features a larger working bandwidth and a higher output voltage than Model A. Model B performs better than Model A in comparable experimental settings. Simple study revealed that Model B’s electromagnetic energy harvesting produced superior outcomes. Additionally, it indicates that a nonlinear spring may be able to raise the output voltage and widen the frequency bandwidth. Full article

Vibration energy harvesting from ambient mechanical sources offers a sustainable alternative to batteries for powering low-power electronics in remote environments, yet challenges persist in achieving broadband efficiency, low-frequency operation, and concurrent vibration suppression. Here, we introduce a pyramidal piezoelectric sandwich beam (PPSB) with periodic elastic constraints, leveraging homogenized lattice truss cores for enhanced electromechanical coupling. Using Lagrange equations, we derive the coupled dynamics, validated against finite element simulations with resonant frequency errors below 3%. Compared to equivalent-stiffness uniform beams, the PPSB exhibits 3.42-fold higher voltage and 11.68-fold greater power output, attributed to optimized strain distribution and resonance amplification. Parametric analyses reveal trade-offs: increasing core thickness or spring stiffness elevates resonant frequencies but reduces voltage peaks due to stiffness–strain imbalances; conversely, a larger beam length, truss radius or tilt angle will reduce the natural frequency while increasing the output through inertia and shear enhancement. Piezoelectric constants and load resistance minimally affect mechanics but optimize electrical impedance matching. This single-phase, geometrically tunable design bridges gaps in multifunctional metamaterials, enabling self-powered sensors with vibration attenuation for aerospace, civil infrastructure, and biomedical applications, paving the way for energy-autonomous systems. Full article

In this study, the operation features of a transformerless voltage divider, with transistor–diode commutation of switchable capacitors, designed to operate as a part of low-power autonomous electronic systems with reduced output voltage are studied both theoretically and experimentally. The analysis is carried out for a divider operation with a constantly or periodically connected voltage source V₀ with unlimited power. It is found that the divider’s efficiency during operation with a constantly connected primary voltage source V₀ with unlimited power is very low. However, the efficiency can reach 60% during the divider’s operation using a periodically connected voltage source V₀ with unlimited power. It has been shown that the efficiency can only reach 40% in the case of using a voltage source with limited power connected to the divider periodically. It has been established that for circuits with transistor–diode commutation of the capacitors, the stabilization effect is much stronger than for circuits with diode commutation of the capacitors. Therefore, an excess of the maximum load voltage relative to the expected value V₀/N is significantly lower for transistor–diode commutation in comparison with diode commutation (N is the number of divider stages). Based on the ideas developed regarding the divider operation, analytical expressions are obtained, enabling us to calculate the parameters of the studied divider circuits in a wide range. The good agreement between the analytical estimations and experimental data suggests that these calculations adequately describe the operation of the dividers, and that the derived analytical expressions can be successfully used during the preliminary design stage. In general, the analysis carried out herein and the developed approach make it possible to significantly narrow the range of search for the necessary system parameters when designing voltage dividers. Full article

Computational analysis using PSpice has become an indispensable tool for evaluating power electronics circuits, as it allows accurate simulation of transient effects, ripple, and component dynamics, enabling reliable assessment of complex topologies before physical implementation. In single-phase systems, electrolytic components are commonly used due to their high energy density, which helps mitigate low-frequency ripple caused by power oscillations between the DC and AC sides. However, these components have a limited lifespan, which compromises the system’s long-term reliability. This work proposes and evaluates the Stacked Switched Capacitor (SSC) topology as a power decoupling technique, implemented within a 200 W Cuk converter. The proposed SSC design enables a substantial reduction in required capacitance, replacing a conventional 600 μF capacitor with only three 36 μF capacitors, while maintaining voltage stability and output power performance. Simulation results show a high efficiency of 94% and a DC-link energy of 0.992 J, confirming the SSC’s ability to effectively mitigate voltage ripple at twice the grid angular frequency (2ω, rad/s) without compromising system durability. Comparative analysis with conventional decoupling strategies demonstrates that the SSC topology offers a compact, efficient, and reliable alternative, reducing the number of required passive components and switching devices. These results provide a strong basis for further exploration of SSC-based designs in space- and cost-constrained single-phase DC-AC applications. Full article