Search Results (6,925)

This study systematically investigated the structural damage and electrochemical performance changes in 18650 cylindrical lithium-ion batteries under multiple impacts through a 10 kg drop-hammer impact test. The experimental results showed that as the state of charge (SOC) increased from 25% to 75%, the battery’s stiffness increased and its impact resistance improved, but the electrolyte leakage intensified, with a higher risk of leakage at high SOCs. An increase in the impact force led to enhanced voltage fluctuations and a continuous increase in deformation. After an impact of 500 mm, the voltage decreased about 0.02 V, while after an impact of 1000 mm, it dropped about 0.04 V. Axial impacts caused a sudden voltage drop to 1.96 V, resulting in permanent failure; compared with planar impacts, cylindrical surface impacts are more likely to cause compression in the middle and warping at both ends, significantly increasing the risk of internal short circuits. CT scans revealed that the battery porosity can reach up to 3.09% under high impact energy, and the deformation rate can reach 28.39%. The research results provide a quantitative experimental basis for the impact-resistant design and safety assessment of power batteries. Full article

As stability is one of the most important property of any system, studying it is paramount when performing a power-hardware-in-the-loop simulation in an experimental setup. To guarantee the proper operation of such a system, a thorough understanding of the critical issues regarding the dynamics of the power amplifier, the real-time simulated system and the hardware under test is required. Thus, this paper provides a detailed analysis of the correct design of the real-time simulation modeling for the secure and reliable execution of power-hardware-in-the-loop simulations involving power electronic devices in an experimental setup. Specifically, the stability region of a power-hardware-in-the-loop simulation in an experimental AC microgrid setup involving two parallel three-phase grid-following inverters with LCL filters is studied. Through experimental testing, the stability boundaries of the power-hardware-in-the-loop simulation in the experimental setup is determined, demonstrating a direct relationship between the short-circuit ratio of the utility grid and the cutoff frequency of the feedback current filter. Experimental evidence confirms the capability of the AC microgrid setup to achieve smooth transitions between diverse operating conditions and determine stability boundaries with parameter variations. This research provides practical design guidelines for modeling and the real-time simulation to ensure stability in the power-hardware-in-the-loop simulations in experimental setups involving actual grid-following inverters, specifically using an Opal-RT platform with a voltage-source ideal transformer model and parameter variations in the short-circuit ratio from 2 to 20, the line impedance ratio $X/R$ from 7 to 10, and the feedback-current-filter cutoff frequency from 100 to 1000 kHz. Full article

Efficient routing optimization remains a pivotal challenge in Electronic Design Automation (EDA), as it profoundly influences circuit performance, power consumption, and manufacturing cost. The Rectilinear Steiner Minimum Tree (RSMT) problem plays a crucial role in this process by minimizing the routing length through the introduction of Steiner points. This paper proposes a reinforcement learning-driven RSMT construction model that incorporates a novel Selective Kernel Transformer Network (SKTNet) encoder to enhance feature representation. SKTNet integrates a Selective Kernel Convolution (SKConv) and an improved Macaron Transformer to improve multi-scale feature extraction and global topology modeling. Additionally, Self-Critical Sequence Training (SCST) is employed to optimize the policy by leveraging a greedy-decoded baseline sequence for the advantage computation. Experimental results demonstrate superior performance over state-of-the-art methods in wirelength optimization. Ablation studies further validate the contribution of this model, highlighting its effectiveness and scalability for routing. Full article

A compact electrochemical sensor module for pH detection was developed for potential integration into specialized devices used for live cell or tissue incubation, for applications in highly parallelized cell culture analysis, by incorporating Organ-on-Chip devices. This research focuses on the deposition, structural and chemical analysis, and functional characterization of different titanium-oxide layers with various compositions as potentially sensitive materials for pH sensing applications. The titanium-oxide layers were deposited using vacuum sputtering and atomic layer deposition at 100 °C and 300 °C, respectively. Transmission electron microscopy and X-ray photoelectron spectroscopy were utilized to determine the specific composition and structure of different titanium-oxide layers. These TiO_x-functionalized electrodes were connected to the application-specific analog front-end chip of the low-power readout circuit for precise evaluation. The pH sensitivity of the differently modified electrodes, employing various TiO_x materials, was evaluated using pH calibration solutions ranging from pH 6 to 8. Among the various deposition solutions, such as sputtering or high-temperature atomic layer deposition, the TiO_x layer deposited using low-temperature atomic layer deposition proved more suitable for pH sensing applications, with a sensitivity of 54.8–56.7 mV/pH, which closely approximates the Nernstian response. Full article

In this paper, a method to improve the protection of a four-core power cable of a salt-producing floating platform equipped with an automatic breaker with an independent tripping mechanism is suggested. The use of this automatic breaker in combination with a suggested protection device ensures reliable protection of not only the power cables of the platform against all faults but also the personnel of the platform and animals on the reservoir banks against electric shock in the event of a single-phase ground fault in reservoir water. This would be possible due to a voltage sensor made in the form of a metal ring on the power cable and a relay; one terminal of the relay winding is connected to the voltage sensor by a single-core control cable, and the other to the neutral of a power source on the platform. The typically open contacts of this relay are connected to an electric circuit which includes a power source and a coil for an independent tripping mechanism of the automatic breaker. This design ensures reliable operation of the suggested protection device in the event of a single-phase ground fault in the power cable of the platform when underwater cable insulation is damaged. Full article

Matroid is a mathematical structure that extends the concept of independence. The fuzzy graphic binary matroid serves as a generalization of linear dependence, and its properties are examined. Power grid networks, which manage the generation, transmission, and distribution of electrical energy from power plants to consumers, are inherently a complex system. A key objective in analyzing these networks is to ensure a reliable and uninterrupted supply of electricity. However, several critical issues must be addressed, including uncertainty in communication links, detection of redundant or sensitive circuits, evaluation of network resilience under partial failures, and optimization of reliability in interconnected network systems. To support this goal, the concept of a fuzzy graphic binary matroid is applied in the analysis of power grid communication network, offering a framework that not only incorporates fuzziness and binary conditions but also enables systematic identification of weak circuits, redundancy planning, and reliability enhancement. This approach provides a more realistic representation of operational conditions, ensuring better fault tolerance and improved efficiency of the grid. Full article

Wireless power transfer (WPT) has emerged as a compelling solution for delivering electrical energy without physical connectors, particularly in applications requiring reliability, mobility, or encapsulation. This work presents the modeling, simulation, construction, and experimental validation of an optimized dual-frequency WPT system using magnetically coupled resonant coils. Unlike conventional single-frequency systems, the proposed architecture introduces two independently controlled excitation frequencies applied to distinct transistors, enabling improved resonance behavior and enhanced power delivery across a range of coupling conditions. The design process integrates numerical circuit simulations in PSpice and three-dimensional electromagnetic analysis in ANSYS Maxwell 3D, allowing accurate evaluation of coupling coefficient variation, mutual inductance, and magnetic flux distribution as functions of coil geometry and alignment. A sixth-degree polynomial model was derived to characterize the coupling coefficient as a function of coil separation, supporting predictive tuning. Experimental measurements were carried out using a physical prototype driven by both sinusoidal and rectangular control signals under varying load conditions. Results confirm the simulation findings, showing that specific signal periods (e.g., 8 µs, 18 µs, 20 µs, 22 µs) yield optimal induced voltage values, with strong sensitivity to the coupling coefficient. Moreover, the presence of a real load influenced system performance, underscoring the need for adaptive control strategies. The proposed approach demonstrates that dual-frequency excitation can significantly enhance system robustness and efficiency, paving the way for future implementations of self-adaptive WPT systems in embedded, mobile, or biomedical environments. Full article

This paper presents a microstrip active quasi-circulator designed for low-power wireless communication systems. The circuit consists of a second-order Wilkinson power divider and two power amplifiers with high gain and ultra-low noise characteristics. By leveraging the unidirectional transmission characteristics of the transistors and the isolation provided by resistors within the power divider, the interference between the transmitter (TX) and receiver (RX) is effectively suppressed. Additionally, thanks to the dual-amplifier architecture, no extra power amplification circuitry is required, thereby reducing the overall complexity and power consumption of the communication system. The detailed design procedure of the proposed quasi-circulator is presented. The measurement results show that, within the frequency range of 4.75 GHz to 6.11 GHz, the isolation between the TX and RX ports exceeds 20 dB, the return loss at each port is greater than 10 dB, and the transmission gains from the TX port to the antenna and from the antenna to the RX port are 3.1–8.7 dB and 2.7–4.0 dB, respectively, demonstrating a relative bandwidth of 25%. Full article

A radiation-hardened RCC (Ring Choke Converter) isolated power supply design is proposed, which provides an innovative solution to the challenge of providing stable power to the PWM controller in DC-DC converters under nuclear radiation environments. By optimizing circuit architecture and component selection, and incorporating transformer isolation and dynamic parameter compensation technology, the RCC maintains an 8.9 V output voltage after exposure to neutron irradiation of 3 × 10¹³ n/cm², significantly outperforming conventional designs with a failure threshold of 1 × 10¹³ n/cm². For the first time, the degradation mechanisms of VDMOS devices under neutron irradiation during switching operations are systematically revealed: a 32–36% reduction in threshold voltage (with the main power transistor dropping from 5 V to 3.4 V) and an increase in on-resistance. Based on these findings, a selection criterion for power transistors is established, enabling the power supply to achieve a 2 W output in extreme environments such as nuclear power plant monitoring and satellite systems. The results provide a comprehensive solution for radiation-hardened power electronics systems, covering device characteristic analysis to circuit optimization, with significant engineering application value. Full article

To meet safety regulations in underground coal mines, wireless power transfer (WPT) systems must house both the transmitter and receiver within explosion-proof enclosures. However, eddy currents induced on the surfaces of these non-ferromagnetic metal enclosures significantly hinder magnetic flux coupling, thereby reducing transmission efficiency. This paper proposes a slotting technique applied to explosion-proof enclosures to suppress eddy currents, along with the integration of magnetic flux focusing materials into the coils to enhance coupling. Simulations were conducted to compare three system configurations: (i) a WPT system without enclosures, (ii) a system with solid (unslotted) enclosures, and (iii) a system with slotted enclosures. The results show that solid enclosures reduce efficiency to nearly zero, whereas slotted enclosures restore efficiency to 90% of the baseline system without enclosures. Joule heating remains low in the slotted explosion-proof enclosures, with energy losses of 2.552 J for the transmitter enclosure and 2.578 J for the receiver enclosure. A conservative first-order estimation confirms that the corresponding temperature rise in the enclosure surfaces remains below 50 °C, which is well within the 150 °C limit stipulated by the Chinese National Standard GB 3836.1-2021 (Explosive Atmospheres—Part 1: Equipment General Requirements). These findings confirm effective eddy current suppression and efficiency recovery without compromising explosion-proof safety. The core innovation of this work lies not merely in the physical slotting approach, but in the development of a precise equivalent circuit model that fully incorporates all mutual inductance components representing eddy current effects in non-ferromagnetic explosion-proof enclosures, and its integration into the overall MCR-WPT system circuit. Full article

Gallium nitride high electron mobility transistors (GaN HEMTs), characterized by their extremely high switching speeds and superior high-frequency performance, have demonstrated significant advantages, and gained extensive applications in fields such as aerospace and high-power-density power supplies. However, their unique internal architecture renders these devices highly sensitive to circuit parasitic parameters. Conventional circuit design methodologies often induce severe issues such as overshoot and high-frequency oscillations, which significantly constrain the realization of their high-frequency performance. To solve this problem, this paper investigates the nonlinear dynamic behavior of GaN HEMTs during switching transients by establishing an equivalent impedance model. Based on this model, a detailed analysis is implemented to elucidate the mechanism by which RC Snubber circuits influence the system’s resonance frequency and the amplitude at the resonant frequency. Through this analysis, an optimal RC Snubber circuit parameter is derived, enabling effective suppression of high-frequency oscillations during the switching transient of GaN HEMT. Experimental results demonstrate that the proposed design achieves a maximum reduction of 40% in voltage overshoot, shortens the ringing time to one-twentieth of the original value, and suppresses noise by 20 dB in the high-frequency range of 20 MHz to 30 MHz, thereby significantly enhancing the stability and reliability of circuit operation. Additionally, considering the heat dissipation requirements in high power density scenarios, this work optimizes the layout of devices, and heat sinks to maintain operational temperatures within safe limits, further mitigating the impact of parasitic parameters on overall system performance. Full article

Plant microbial fuel cells (PMFCs) represent an eco-friendly solution for generating clean energy by converting biological processes into electricity. This work presents the first integration of tin sulfide (SnS)-coated 304 stainless steel (SS304) electrodes into Aloe vera-based PMFCs for enhanced energy harvesting. SnS thin films were obtained via chemical bath deposition and screen printing, followed by thermal treatment. X-ray diffraction (XRD) revealed a crystal size of 15 nm, while scanning electron microscopy (SEM) confirmed film thicknesses ranging from 3 to 13.75 µm. Over a 17-week period, SnS-coated SS304 electrodes demonstrated stable performance, with open circuit voltages of 0.6–0.7 V and current densities between 30 and 92 mA/m², significantly improving power generation compared to uncoated electrodes. Polarization analysis indicated an internal resistance of 150 Ω and a power output of 5.8 mW/m². Notably, the system successfully charged a 15 F supercapacitor with 8.8 J of stored energy, demonstrating a practical proof-of-concept for powering low-power IoT devices and advancing PMFC applications beyond power generation. Microbial biofilm formation, observed via SEM, contributed to enhanced electron transfer and system stability. These findings highlight the potential of PMFCs as a scalable, cost-effective, and sustainable energy solution suitable for industrial and commercial applications, contributing to the transition toward greener energy systems. These incremental advances demonstrate the potential of combining low-cost electrode materials and energy storage systems for future scalable and sustainable bioenergy solutions. Full article

With the increasing demands of the grid on power electronic converters, active neutral-point-clamped (ANPC) converters have been widely adopted due to their flexible modulation strategies and wide-range power regulation capabilities. To address grid-integration testing requirements for ANPC converters, this paper comparatively studies three electromagnetic transient (EMT) modeling approaches: switch-state prediction method (SPM), associated discrete circuit (ADC), and time-averaged method (TAM). Steady-state and transient simulations reveal that the SPM model achieves the highest accuracy (error ≤ 0.018%), while the TAM-based switching function model optimizes the efficiency–accuracy trade-off with 6.4× speedup versus traditional methods and acceptable error (≤2.62%). Consequently, the TAM model is implemented in a real-time hardware-in-the-loop (HIL) platform. Validation under symmetrical/asymmetrical grid faults confirms both the model’s efficacy and the controller’s robust fault ride-through capability. Full article

The reliability of the generator circuit breaker (GCB) switching coil affects the safe and stable operation of the power system, in which the faults of abnormal voltage, poor contact, and mechanical jamming of the switching coil can easily lead to the refusal of the circuit breaker, which threatens the safety of the power grid. In order to study the fault characteristics of the GCB switching coil, this paper combines multi-physical field simulation and experimental testing, establishes the electromagnetic field simulation model of the switching coil, and analyzes the characteristics of current waveforms under typical faults such as voltage abnormality, poor contact, and core jamming. Through simulation and testing to verify the mechanism of current waveform distortion under different fault states, demonstrated the change rule of characteristic parameters when the fault occurs, and provided a basis for the diagnosis of the operation status of the switching coil based on current waveform. Full article

Traditional active magnetic bearing power amplifiers usually adopt hard-switching circuit topologies with simple structures and strong practicability. However, such topologies suffer from high switching losses and easy generation of current noise. To address these issues, this paper proposes a soft-switching power amplifier topology for active magnetic bearings. By employing soft-switching technology, zero-voltage notches are generated through an auxiliary resonant circuit, enabling the switching transistor s to turn on and off at the zero-voltage notch moment, thereby reducing switching losses and improving system efficiency. The working principle of the soft-switching power amplifier topology is analyzed in detail, and the proposed scheme is verified through system simulation and experiments. Results show that the soft-switching power amplifier can effectively reduce switching losses and current noise, while its dynamic performance and operating bandwidth are comparable to those of traditional hard-switching power amplifiers. With an output current of 3 A, the efficiency of the soft-switching power amplifier can be enhanced by 10%. Full article