Search Results (837)

With the rapid development of sustainable photovoltaic power generation, energy-storage-coordinated grid-connected photovoltaic systems have been widely adopted to stabilize power output and enhance grid adaptability. Aiming at the low fault tolerance of conventional photovoltaic grid-connected systems under grid voltage swell disturbances, this paper designs a single-stage power management system for grid-connected photovoltaic generation and studies its energy-storage-coordinated high-voltage ride-through (HVRT) technology. The single-stage topology boasts simple structure, low cost and high conversion efficiency, yet faces prominent stability risks under voltage swell faults. The system integrates photovoltaic units, energy storage modules and grid-connected interfaces to implement flexible bidirectional power dispatching. A three-phase AC/DC converter realizes photovoltaic maximum power point tracking (MPPT), and the energy storage module connects to the DC bus via a dual half-bridge (DHB) converter to restrain power fluctuations. Under HVRT faults, the energy storage coordination strategy elevates DC bus voltage to maintain stable grid-tied operation without disconnection. Different from schemes requiring extra hardware or complicated control optimization, the proposed method realizes stable bus voltage regulation and flexible energy scheduling with zero additional hardware cost. Simulations and experiments validate the rationality, feasibility and outstanding fault-ride-through performance of the designed system. Full article

Aiming at the tracking control of the Z-source inverter (ZSI), this paper takes into account the dependence of existing control methods on system dynamic models and the low tracking accuracy of conventional model-based control. To address these issues, an improved fractional-order model-free adaptive control (IFOMFAC) strategy is proposed. First, the dynamic process of the ZSI is analyzed to identify the control inputs and objectives of the control system. Then, a PID-IFOMFAC algorithm is designed, based on the fractional-order dynamic linearization data model of the system, to achieve voltage stabilization control with the ZSI. The method combines fractional-order dynamic linearization with a PID-type structure, enhancing the inverter’s response speed and tracking accuracy under input voltage disturbances and load variations. Using a data-driven method, IFOMFAC reduces the reliance of traditional control strategies on precise system models. It only uses the input–output data from the ZSI during operation for control input. This approach achieves effective dynamic control and ensures good adaptability. Numerical simulations show that the proposed method achieves better performance than conventional FOMFAC and PI control in terms of capacitor voltage dynamic response, shoot-through duty cycle regulation, and system stability, especially under abrupt input voltage changes, demonstrating stronger dynamic adaptation and lower overshoot. Full article

With an increase in the High-Voltage Direct Current (HVDC) infeed, the strength of the receiving-end AC grid decreases, leading to transient voltage instability. Voltage source converter (VSC)-HVDC stations have a large unit capacity and high controllability, offering great potential for voltage support of the receiving-end grid. A grid-following/grid-forming (GFL–GFM) hybrid control can improve the oscillation stability of VSC stations under both strong and weak grid conditions; however, most relevant studies have focused on oscillation stability, while little attention has been paid to transient voltage regulation performance. Moreover, a quantitative analysis method for the transient active- and reactive-power characteristics of the hybrid control is lacking. This paper proposes a series-connected GFL/GFM hybrid control strategy along with a quantitative dynamic power analysis method. By establishing the closed-loop transfer function model, the steady-state power control performance and transient reactive-power response of the proposed control are quantitatively analyzed. Electro-Magnetic Transient (EMT) simulation results verify that, compared with the existing hybrid synchronization-type control, the proposed series-connected scheme exhibits superior performance in mitigating transient low-voltage and overvoltage issues, with the minimum voltage dip improved from 0.3 p. u. to 0.8 p. u. and the maximum overvoltage after fault clearance decreasing from 1.38 p. u. to 1 p. u. Full article

This paper proposes an adaptive low-voltage ride-through (LVRT) control framework for grid-forming virtual synchronous generators (VSGs) in weak and ultra-weak grids based on feasible-region and fault ride-through limit-boundary analysis. The proposed method achieves coordinated active–reactive power regulation during fault conditions and enhances the fault ride-through capability and synchronization stability of the system. First, an equivalent voltage-vector decomposition is used to establish the fault-stage operating model of the VSG, based on which the feasible active–reactive power region is characterized under current, line-reactance, and apparent-power constraints. Then, the maximum active power transfer capability, maximum reactive power support capability, and critical voltage-sag boundary are derived by considering both current limitation and power-angle stability. Furthermore, unlike existing feasible-domain-based methods that mainly focus on voltage-command limitation, a unified power-circle–capability-cone constraint model is developed to directly generate feasible active–reactive power references within the original VSG framework. A voltage-dependent adaptive droop coefficient is introduced to dynamically coordinate active and reactive power allocation, thereby enlarging the feasible LVRT region and improving the stability margin. Finally, a distributed consensus mechanism is designed to coordinate active and reactive power references among multiple VSGs within their feasible regions and suppress fault-induced power oscillations. Simulation results verify that the proposed method enhances voltage support, expands the feasible LVRT operating region, suppresses power and power-angle oscillations, and improves transient stability under weak-grid conditions. Full article

The rapid growth of artificial-intelligence (AI) and high-performance computing workloads has reshaped the power-delivery requirements of high-bandwidth memory (HBM), neural processing units (NPUs), and advanced systems-on-chip (SoCs). These platforms draw large currents that vary rapidly at aggressively scaled supply voltages, so their on-chip regulators must combine high current density, nanosecond-scale settling with minimal droop, wideband power-supply rejection (PSR), and stable capacitor-less operation, while also mitigating issues such as power supply-induced jitter (PSIJ) in high-speed clock and data paths. On-chip low-dropout (LDO) regulators have become the key building block at the point of load, and a wide range of architectures have emerged to meet these demands. This paper reviews on-chip LDOs for HBM and SoC power integrity. We translate application-level power-integrity requirements, including PSIJ, into circuit specifications; organize the design space into fast-transient, wideband high-PSR, high-current and distributed, and capacitor-less and digital/hybrid architectures; benchmark representative state-of-the-art designs using both conventional and application-relevant metrics such as data rate, jitter, and eye margin; and distill the resulting technology trends. Full article

Multi-module DC–DC converters are well suited to shipboard DC power systems with stringent requirements for high power density, operational safety, and continuous power supply. By distributing the system voltage, current, and power among multiple submodules (SMs), the modular architecture reduces device stresses and facilitates capacity expansion, maintenance, and redundant operation. Among the available modular configurations, the input-series output-parallel (ISOP) structure is particularly suitable for interfacing high-voltage DC buses with low-voltage, high-current loads. However, conventional voltage- or current-sharing strategies generally neglect efficiency differences among SMs. Under equal power sharing, low-efficiency SMs generate greater losses and experience higher thermal stress, resulting in thermal imbalance and accelerated aging. To address this issue, an efficiency-consensus-based power-distribution strategy is proposed for ISOP LLC-DAB hybrid converters. A distributed efficiency observer based on multi-agent consensus theory dynamically regulates the power references according to the relative efficiencies of the SMs, allowing high-efficiency modules to process more power while reducing the loading of low-efficiency modules. Experimental results obtained from a three-module prototype include comparative efficiency measurements and temperature-distribution tests. The results demonstrate that the proposed strategy improves the efficiency consistency among the three SMs, redistributes power according to their relative efficiency states, and reduces the temperature difference among the modules, thereby mitigating localized loss concentration and thermal imbalance. The proposed method provides a feasible solution for improving the electrothermal operating conditions of modular DC–DC converters. The achieved reduction in thermal imbalance may contribute to enhanced long-term reliability by alleviating uneven electrothermal stress. Full article

Continuous operation is increasingly expected of Internet of Things (IoT) and wireless sensor network (WSN) nodes, yet practical solar front ends must account for source variability, intermediate storage, conversion losses, sensing overhead, and battery-management constraints. This article develops and evaluates a discrete, two-stage photovoltaic front end for such nodes: a perturb-and-observe (P&O) buck stage tracks the maximum power point of a 20 W Solarland SLP020-12U module (rated 17.2 V, 1.16 A) and feeds an intermediate storage bus, while a PI-compensated SEPIC stage regulates the IoT rail to 3.2 V independently of that bus voltage. Closed-loop MATLAB/Simulink simulations are reported at 1000, 800, and 600 W/m². The reported conversion figures originate from an idealized switching model and should therefore be interpreted as simulation-only values rather than measured prototype efficiency. A low-cost Arduino-based prototype confirms correct switching behavior and a 20.0048 kHz PWM signal, but the available captures lack synchronized, calibrated input/output power logging; consequently, no hardware efficiency, MPPT tracking efficiency, regulation error, ripple, or settling-time figure is claimed. The revised manuscript makes this simulation-to-hardware boundary explicit, adds the power cost of sensing and data conversion to the loss discussion, strengthens the battery-management and deployment caveats, and defines the measurements required for full quantitative validation. Full article

Direct-drive wave power generation systems based on permanent magnet linear generators (PMLGs) produce fluctuating electromagnetic power under irregular wave excitation, which may affect DC-bus voltage stability and load-side power quality. To smooth the fluctuating output power, this paper develops an empirical mode decomposition (EMD)-based power allocation strategy for a battery–supercapacitor hybrid energy storage system (HESS). In the proposed strategy, EMD is used to decompose the fluctuating electromagnetic power into low-frequency and high-frequency components according to their time-scale characteristics. The low-frequency component is assigned to the battery for energy buffering, while the high-frequency component is assigned to the supercapacitor for transient power compensation. Finite-control-set model predictive current control (FCS-MPCC) is adopted on the generator side to improve the current response of the PMLG, and an MPC-based HESS controller is designed to track the assigned power commands and regulate the DC-bus voltage. Simulation results show a battery power-tracking error of 3.93 W and a DC-bus voltage standard deviation of 0.108 V; compared with LPF, EMD reduced the load-step voltage deviation by 11.94%. Experiments confirm that the PMLG back-EMF follows the translator velocity, the storage currents track their references, and the DC-bus voltage remains within ±2 V of its reference. Full article

Incorporating energy generated from regular human movement into wearable electronics offers a promising alternative to conventional batteries, enabling devices to power themselves by harvesting energy from motion and the surrounding environment. Ambient energy harvesting provides a pathway toward limitless, self-sustaining power and supports the development of cleaner, smarter wearable systems. Among various approaches, integrating hybrid mechanisms into footwear represents a transformative solution for sustainable power generation. In this work, a piezoelectric generator (PEG), an electromagnetic generator (EMG), and a triboelectric generator (TEG) were hybridized within a single architecture to harvest biomechanical energy from walking, jogging, and running. The device incorporates pressure-sensitive Lead Zirconate Titanate (PZT) sheets, a spiral spring with dual neodymium (NdFeB) magnets with wound copper coils, and a nickel foam with polytetrafluoroethylene (PTFE) for triboelectricity operating in contact–separation mode. A dedicated energy-management circuit comprising independent rectification, DC bus energy aggregation, supercapacitor storage, and voltage regulation was implemented to efficiently utilize the harvested energy. The system was optimized through simulation using SOLIDWORKS 2023 and validated experimentally by using LabVIEW-NI myRIO FPGA system and treadmill. The proposed hybrid device achieved an exceptional peak output power of 58 mW and a voltage of 7.4 V, enough to charge low-power wearable devices, significantly surpassing the performance of most reported standalone and hybrid insole energy harvesters. These results demonstrate the effectiveness of multimodal integration in broadening operational bandwidth, increasing energy density, and enhancing compatibility with wearable applications. Piezoelectric, Electromagnetic and Triboelectric Insole Energy Harvesting (PET-IEH) establishes a new benchmark in biomechanical energy harvesting and paves the way for next-generation self-powered and sustainable wearable electronics. Full article

This study proposes a self-condensing water-electrode plasma device in which ambient water vapor is condensed on a cooled needle-tip electrode within a strong electric-field region, forming continuously renewed water droplets, Taylor cones, or water-film interfaces that participate in the discharge process. The effects of ambient humidity, needle-tip temperature, and applied voltage on the self-condensation behavior were investigated. The discharge modes at different applied voltages and discharge gaps, the generation of reactive species, and the inactivation efficacy against Staphylococcus aureus were also analyzed. The results showed that increasing ambient humidity, decreasing the needle-tip temperature, and increasing the applied voltage all promoted water condensation at the needle tip. The electric field shortened the droplet formation time and reduced the droplet detachment size. As the applied voltage increased, the device sequentially underwent water condensation, electrospray, stable Taylor-cone, water-film discharge, and bare-electrode discharge stages, while the boundary voltage of each stage increased with the discharge gap. The ozone concentration remained below the instrument’s limit of detection during discharge with the self-condensing water electrode, whereas hydroxyl-radical generation was significantly enhanced. Compared with a conventional metal electrode, the self-condensing water electrode exhibited greater inactivation of S. aureus at the same applied voltage, with a more pronounced advantage under low-voltage conditions. These findings demonstrate that introducing a self-condensing water interface can regulate the local discharge morphology and reactive-species composition, providing a new strategy for developing low-temperature plasma sterilization technologies with low ozone production and high bactericidal activity. Full article

Solid-state sodium metal batteries are promising for large-scale energy storage owing to their high safety, abundant sodium resources, and low material cost. However, NASICON-type solid-state electrolytes, such as Na₃Zr₂Si₂PO₁₂, still suffer from limited room-temperature ionic conductivity and poor ceramic densification. Herein, a multivalent co-doping strategy using Zn²⁺, Sc³⁺, Hf⁴⁺, and Nb⁵⁺ was employed to regulate the crystal structure, sintering behavior, and Na⁺ transport properties of NASICON electrolytes. The effects of isovalent and aliovalent dopants were systematically investigated by XRD, Rietveld refinement, SEM-EDS, bond-valence-site calculations, and electrochemical impedance spectroscopy. The optimized monoclinic Na_3.167Zn_0.167Hf_0.167Zr_1.5Nb_0.167Si₂PO₁₂ electrolyte delivered a room-temperature total ionic conductivity of 1.16 mS cm⁻¹ and an activation energy of 0.35 eV, mainly due to optimized Na⁺ migration-channel geometry and enhanced ceramic densification. Na||Na symmetric cells exhibited stable cycling for 500 h with a maximum polarization voltage of 20 mV. Furthermore, solid-state Na||Na₃V₂(PO₄)₃ cells retained 95% capacity after 624 cycles at 1 C. This work provides a feasible doping strategy for advanced NASICON electrolytes and solid-state sodium metal batteries. Full article

Smart textile interfaces hold promise for battery-free wearable interaction, yet their adoption is limited by complex fabrication and insufficient on-body evaluation. We present TriboTex, a low-cost spray-patterning workflow that forms nylon–Cu–nylon triboelectric stacks on cotton textiles using laser-cut PET stencils and commercially available materials. The core consumables cost approximately USD 0.003/cm², and sensor geometry can be rapidly iterated by modifying only the digital stencil. Controlled characterization across nine devices from three fabrication batches showed a peak open-circuit voltage of 52.3 V and a maximum power density of 1870 µW/m² at 4 GΩ. The output retained 96.1% of its initial voltage after 1000 bending cycles and 94.2% after 24 h of simplified saline immersion. Three-sample environmental sweeps showed voltage amplitudes of 41.9–43.7 V from 15 to 45 °C, with a decrease to 27.7 V at 0 °C; the humidity response remained within 92.7–104.5% of the 20% RH value over 20–60% RH but decreased to 19.9% at 70% RH. Two wearable prototypes were developed: a single-electrode garment sleeve recognized tap, double-tap, and swipe gestures with 95.0% accuracy across 1200 trials from 12 participants; a single-electrode insole generated action-dependent peak voltages up to 123 V under repeated foot loading and was connected through a rectification and voltage-regulation module to charge a battery. Across the two 12-participant studies, attachment and fit stability emerged as shared integration requirements, while participant feedback and controlled humidity measurements highlighted moisture management as a priority for reliable on-body sensing and energy capture. The primary contribution is an accessible, low-cost, and geometry-flexible route for early-stage wearable sensing experiments and application demonstrations, supported by documented fabrication, electrical characterization, and human-centered evaluation. Full article

Attractive electromagnetic actuators operated under open-loop control are susceptible to positive feedback instability because the attractive force increases as the separation decreases, making it difficult for the actuator to remain at an intermediate position. Here, we propose a prestretched repulsive electromagnetic–elastomer artificial muscle and establish a force-balance model based on the intersection between the electromagnetic repulsive-force curve and the elastomer restoring-force curve. In the repulsive configuration, the electromagnetic force decreases as the coil separation increases, whereas the elastic restoring force increases with tensile displacement; their intersection can therefore define a locally stable mechanical equilibrium position. Natural rubber was used for quantitative model construction and trend validation. Under a constant-voltage input of 36 V and an initial coil separation of 3 mm, the model predicted equilibrium displacements of 0.42 and 0.79 mm for the non-prestretched and 100% prestretched conditions, corresponding to theoretical actuation strains of 14.0% and 52.7%, respectively. Five repeated cycles using the same actuator yielded actual displacements of 0.285 ± 0.033 and 0.700 ± 0.033 mm, corresponding to actuation strains of 9.5 ± 1.1% and 46.7 ± 2.2%, respectively. Although the measured outputs were lower than the ideal model predictions, both the model and the experiments showed that prestretch shifted the working point toward a larger displacement and increased the actuation output. The force-balance framework further indicates that changing the electrical input can shift the electromagnetic-force curve and thereby theoretically regulate the intersection position. Because the repulsive force generated by the current coils was limited, a low-modulus two-part silicone rubber was additionally used to construct a macroscopic demonstration prototype. During a limited number of repeated on–off operations, a local elongation of 140–150% and shape recovery after de-energization were observed, demonstrating the feasibility of using the proposed configuration to drive a simplified movable structure. Coil heating was observed during repeated energization, suggesting that Joule heating may become an important engineering constraint on continuous operation and further increases in driving force; its quantitative effect remains to be investigated. These results provide an experimental basis and a theoretical framework for stable-equilibrium design and prestretch-based working-point regulation in repulsive electromagnetic–elastomer actuators. Full article

With the increasing penetration of distributed generation, electric vehicles and single-phase loads in the low-voltage distribution network, flexible interconnected systems face more prominent three-phase unbalance and direct-current (DC)-side voltage regulation problems. Unbalanced loads not only lead to asymmetry of alternating current (AC)-side voltage and current but also introduce low-frequency ripples into the common DC bus through the power-coupling relationship and further cause the neutral-point potential shift of the split capacitors. To address these problems, this paper takes a double-ended flexible interconnection system with an integrated three-level Buck–Boost energy storage interface as the research object and proposes a DC-side total-voltage-neutral-point cooperative control strategy. Firstly, the coupling relationship between AC-side power fluctuation and DC-side voltage state under unbalanced conditions is established to analyze the formation mechanism of DC bus low-frequency ripple and neutral-point potential offset; secondly, based on the neutral-point access characteristic of three-level Buck–Boost, the DC-side modulation quantity is decomposed into a common-mode duty cycle and a differential-mode duty cycle. Among them, the common-mode duty cycle is used to regulate the total power exchange on the energy storage side to achieve DC bus total voltage maintenance and low-frequency ripple suppression; the differential-mode duty cycle is used to regulate the difference between the duty cycles of the upper and lower half-bridges to achieve capacitor charging and discharging distribution regulation and neutral-point potential balance. Finally, a simulation model is built to verify the proposed control strategy. The simulation results show that the proposed method is able to stabilize the DC bus voltage around 800 V under power step disturbance and suppress the midpoint voltage deviation from a low-frequency oscillation of about 10 V to within about ±1 V. This verifies the effectiveness of the control strategy under unbalanced load and power disturbance conditions. Full article

Low organic carbon utilization efficiency is a core bottleneck restricting the application of biofloc technology (BFT) in intensive aquaculture, accompanied by limited total nitrogen removal, excessive biofloc accumulation, and underutilized chemical energy in organic wastes. To address this issue, this study develops a novel biofloc technology–microbial fuel cell (BFT-MFC) coupled system that exploits surplus carbon sources in BFT as electron donors for bioelectricity generation while synergistically enhancing water purification performance. Compared with a conventional standalone BFT system, the coupled system was systematically evaluated in terms of water quality regulation, biofloc control and electricity generation performance. Results showed that the BFT-MFC system maintained relatively stable dissolved oxygen, pH, and temperature throughout the operation period. The ammonia nitrogen concentration remained relatively low in the BFT-MFC system, although a transient increase to approximately 0.35 mg/L occurred around day 20 before subsequently declining, and total nitrogen fluctuated within 4.29–12.87 mg/L, with substantially less accumulation than that observed in the BFT system, in contrast to the control group, where TN continuously rose to a peak of 23.55 mg/L. Total organic carbon was stabilized within a narrower range of 150–245 mg/L, compared with the wide fluctuation of 129.6–360 mg/L in the single BFT system. Additionally, the coupled system exhibited lower net biofloc accumulation based on floc-volume measurements, while maintaining effective water-quality regulation, and the integrated MFC delivered a maximum output voltage of 295.9 mV and a peak power density of 1716.8 mW m⁻². Overall, the BFT-MFC coupled system integrates wastewater purification, biofloc regulation and energy recovery into a single unit, offering a promising sustainable strategy for industrial recirculating aquaculture. Full article