Search Results (3,982)

Series arc faults on the DC side of photovoltaic (PV) systems are a critical hazard that can trigger system fires. Conventional contact-based detection methods suffer from cumbersome installation and high retrofit cost, whereas existing non-contact approaches mostly rely on megahertz-level high-frequency sampling and therefore require expensive radio-frequency instrumentation or high-performance computing platforms. As a result, it remains difficult to simultaneously achieve strong interference immunity and real-time performance on low-cost embedded devices with limited resources. To address this engineering paradox between high-frequency sampling and constrained computational capability, this paper proposes a fully embedded, non-contact arc fault detection system based on a 12–80 kHz low-frequency sub-band selection strategy. By exploiting the physical characteristic of broadband energy elevation induced by arc faults, the proposed strategy avoids dependence on high-bandwidth hardware. Guided by this strategy, a Moebius-topology coaxial shielded loop antenna is employed as the near-field sensor, while an ultra-simplified passive analog front end is constructed directly by using the on-chip programmable gain amplifier and analog-to-digital converter of the microcontroller unit, enabling efficient signal acquisition and fast Fourier transform processing within the target sub-band. To cope with complex background noise in the low-frequency range, an environment-adaptive baseline mechanism based on exponential moving average and exponential absolute deviation is developed for dynamic decoupling. In addition, a lightweight INT8-quantized multilayer perceptron is introduced as a nonlinear auxiliary module, thereby forming a robust hybrid decision architecture with complementary rule-based and artificial intelligence components. Experimental results show that, under the tested household, laboratory, and PV-site conditions, the proposed system achieved an overall detection rate of 97%, while the remaining 3% mainly corresponded to failed ignition or non-sustained arc attempts rather than persistent false triggering during normal monitoring. Full article

Wireless Power Transfer (WPT) systems often face performance limitations due to the right-half-plane zero (RHPz) in conventional constant-current-fed Buck converters, which can lead to negative undershoot and a slow dynamic response. In this paper, we propose a Buck converter topology with an additional active switch in series with the input capacitor. This mechanism-level modification effectively mitigates the RHPz. The operating modes, steady-state behavior, and small-signal characteristics of the converter are systematically analyzed. A tailored control strategy enables independent regulation of input and output capacitor charging times, supporting improved voltage regulation. Experimental results indicate that the proposed converter reduces settling time by approximately 83%, substantially suppresses negative undershoot, and maintains stable voltage regulation under reference step changes and load transients. The converter maintains high efficiency while demonstrating improved dynamic performance and stability relative to conventional topologies, providing a practical approach for advanced WPT applications. Full article

Although secondary control of direct current (DC) microgrids has been widely studied, traditional static current sharing may still cause severe voltage sag under large-signal constant power load (CPL) steps, and many distributed schemes rely on global topology information while showing limited transient disturbance rejection. To address these issues, this paper proposes an observer-assisted, stability-margin-driven prescribed-time distributed secondary control strategy for islanded DC microgrids. A dynamic CPL risk evaluation function updates current-sharing ratios according to converter operating margins, while a distributed prescribed-time observer estimates disturbance envelopes and alleviates high-frequency chattering. Local adaptive gains remove the explicit dependence of controller tuning on global Laplacian eigenvalue information. MATLAB R2024a-based numerical studies show that, under a 6000 W CPL stress scenario, the proposed method limits the maximum voltage drop to 3.37 V, compared with 24.60 V for the conventional virtual current derivative (VCD) method. Under heterogeneous line impedances and a non-ideal digital benchmark, the proposed method yields a normalized current-sharing error of 0.72%, whereas the VCD method exhibits milder voltage transients. These results support the algorithmic effectiveness and numerical robustness of the proposed strategy within the adopted validation environment. Full article

To address the key problems of low-frequency oscillation and insufficient regulation accuracy at the Point of Common Coupling (PCC) in hydro–wind–photovoltaic hybrid systems, which are caused by the randomness of wind and photovoltaic output, the water-hammer effect of hydropower units, and multi-source power coupling, a joint control strategy based on Fractional-Order Proportional Integral Derivative (FOPID) and Co-evolutionary Multi-objective Particle Swarm Optimization (CMOPSO) is proposed. First, a small-signal transfer function model of the system covering photovoltaic inverters, doubly fed induction generators (DFIGs), hydropower units and voltage-source converter-based high-voltage direct current (VSC-HVDC) converter stations is established to accurately characterize the water-hammer effect and multi-source dynamic coupling characteristics. Second, a Caputo-type FOPID controller is designed. Compared with traditional integer-order controllers with limited tuning flexibility, the FOPID controller utilizes its five degrees of freedom to address specific multi-source coupling challenges. This precisely compensates for the non-minimum phase lag caused by the water-hammer effect in hydropower units via the fractional derivative link, and effectively smooths the impact of stochastic wind–solar fluctuations on PCC voltage through the memory characteristics of the fractional integral link. This multi-parameter regulation mechanism prevents a trade-off between response speed and overshoot suppression, achieving effective decoupling of complex multi-source dynamic interactions. Third, a dual-objective optimization framework with the Integral of Time-weighted Absolute Error (ITAE) and Oscillatory Disturbance Risk Index (ODRI) as the objectives is constructed. The multi-population co-evolution mechanism of the CMOPSO algorithm is adopted to solve the Pareto-optimal solution set, realizing the coordinated optimization of dynamic response accuracy and oscillation instability risk. Finally, comparative simulations are carried out on the Simulink platform with traditional PI/FOPI controllers and optimization algorithms such as Multi-objective Particle Swarm Optimization based on the Decomposition/Simple Indicator-Based Evolutionary Algorithm (MPSOD/SIBEA). The results show that the proposed strategy can effectively suppress low-frequency oscillations in the range of 0~30 Hz. Compared with the traditional PI controller, the PCC voltage overshoot is reduced by more than 40%, the oscillation decay time is shortened by 33%, the ITAE and ODRI indices are decreased by 12.58% and 2.47%, respectively, and the stability of DC bus voltage is significantly improved. Its robustness and comprehensive control performance are superior to existing methods, providing an efficient and stable control scheme for power electronics-dominated complex new energy grid-connected systems. Full article

Grid-forming converters, with their voltage-source characteristics, can independently provide voltage support and thus have become a critical supporting technology for new-type power systems. However, they suffer from overcurrent risks and insufficient voltage support capability during grid faults. To overcome these shortcomings, this paper proposes an adaptive transient-voltage support strategy for grid-forming PMSG wind turbines based on DC capacitor-voltage synchronization. First, the inertia synchronization and autonomous-voltage support mechanisms of such grid-forming wind turbines are analyzed. Second, based on power-flow equations and the grid-forming topology, key factors affecting the grid-connected voltage during faults are identified, and an adaptive voltage-support strategy using fuzzy control is developed. Finally, a grid-forming wind power system is modeled on the PSCAD/EMTDC platform, where the proposed strategy raises the minimum PCC voltage to 0.62 p.u. and increases reactive power injection by 0.13 p.u. under a 70% deep sag, successfully fulfilling low-voltage ride-through requirements. Full article

Current-source DC links and their associated power converters require continuous conduction mode (CCM), necessitating specialized switching device configurations. These topologies have gained significant attention due to the increasing adoption of current-mode power distribution systems. The operation of a current-source DC-DC converter relies on temporary magnetic energy storage, typically regulated using established switch-mode power conversion techniques. For a stable current step up or step down the use of the tapped inductor concept can provide an ultimate stable solution for current adjustment and the proposed concept is now developed on a step-down current source DC-DC power converter for the first time to reveal in the power electronics field. The use of tapping concept is similar to a coupled inductor and this allows flexible current modification. In this article, this concept is extended to a family of Tapped inductor current-based DC-DC together with soft-switching to reduce the loss of the switching devices. The key advantage is that it can offer a wide range of current conversions with high efficiency. The theoretical and experimental analysis of the proposed converter family is presented. An experimental prototype of the converter was built and tested, operating with a switching frequency of 100 kHz and accommodating input currents ranging from 1 A to 10 A. The converter achieved current conversion ratios of 0.8, 0.67 and 0.57 times the input current, with an output power range of 1 W to 314 W. The maximum efficiency of 88% was achieved at an output power of 314 W. The high efficiency and wide current conversion range of this current-based converter make it suitable for a variety of applications such as current driving LED systems, photovoltaic (PV) system current source control, and constant current fast charging systems for electric vehicles (EVs). Full article

The thyristor level is the basic unit of ultra-high-voltage and extra-high-voltage direct current (DC) converter valves, and its main-circuit parameters are important indicators for characterizing the health status of converter valves. To meet the demand for efficient detection of converter valve thyristor levels, this paper proposes a parameter inversion method for converter valve thyristor levels by combining the time-frequency-domain features of valve voltage and current, temporal characteristics of feedback signals from the thyristor-level monitoring unit, and a Grey Wolf Optimizer–Backpropagation Neural Network (GWO-BPNN). First, a six-pulse converter valve circuit simulation model is established. Based on this model, the original dataset is generated using the Latin hypercube sampling (LHS) method. Wavelet packet decomposition is then used to extract time-frequency-domain features, and dimensionality reduction is carried out by comparing the coefficient of variation and explained variance ratio so as to obtain input data suitable for neural network training. A BP neural network is then trained, and the network parameters are optimized using the Grey Wolf Optimizer to improve the accuracy and convergence speed of parameter inversion. Simulation comparison results show that the GWO-BP method is more efficient than the state equation method and is suitable for efficient inversion of damping parameters in multi-level thyristor systems. After GWO optimization, the maximum inversion errors of both parameters are reduced to below 5%. Compared with BP, GA-BP, and PSO-BP, the proposed GWO-BP model provides the best overall balance between resistance-inversion accuracy and training efficiency. By further incorporating feedback feature signals, the inversion error can be reduced to 1%. The proposed method provides a new technical route for efficient detection of thyristor converter valves and has broad application prospects. Full article

This paper proposes an innovative control strategy for DC-DC LLC resonant converters, which is based on Reinforcement Learning (RL), specifically utilizing the Tabular Q-Learning algorithm. The presented approach is designed to overcome the limitations of traditional model-based linear controllers and offers two distinct advantages. First, the model-free nature of the algorithm ensures superior robustness: the agent learns the optimal control policy through direct interaction with the converter, implicitly compensating for non-linearities, component tolerances, and parameter drifts caused by aging or thermal stress, without requiring a priori knowledge of the mathematical model. Second, unlike Deep Reinforcement Learning (DRL) techniques, which demand high processing power, the tabular approach guarantees a fast, deterministic execution, which makes the proposed technique highly suitable for implementation on standard microcontrollers in low-cost edge applications. Validation through PLECS simulations demonstrates the controller’s ability to maintain tight voltage regulation even under severe dynamic variations of the input voltage and load. Full article

To address the computational complexity and cumbersome matrix assembly inherent in the Space-Wavenumber Mixed-Domain Method based on the Finite-Element Method (SWMDM-FEM) for three-dimensional (3D) Direct Current (DC) resistivity simulations, we propose an enhanced numerical approach. This approach utilizes two-dimensional (2D) Fourier transform technology to convert the 3D resistivity problem into a one-dimensional (1D) problem within the space-wavenumber mixed domain, which is then solved using the finite-difference method (FDM). By integrating the efficiency of Fourier transform with the simplicity of FDM, this method significantly enhances the efficiency of 3D numerical simulations in DC-resistivity methods. The accuracy of our algorithm is first validated using a spherical anomalous model, followed by testing with a model combining a low-resistivity cuboid and a high-resistivity sphere, demonstrating the method’s superior computational efficiency over the SWMDM-FEM. Subsequently, the proposed algorithm in this paper was tested using a cubic anomaly model. The number of iterations of the algorithm required to achieve the preset convergence accuracy was focused on and counted under different resistivity differences between the anomalous body and the background medium, different total grid numbers in the computational region, and different burial depths of the anomalous body so as to verify that the proposed algorithm has good convergence performance. At the same time, the test results show that under the premise of meeting the preset accuracy requirements, the number of iterations when the algorithm converges is only related to the resistivity difference between the anomalous body and the background medium, and has no correlation with the total number of grid divisions and the burial depth of the anomalous body. Finally, the E-SCAN method was used to carry out three-dimensional observation on the composite model, and the electromagnetic response characteristics of the anomalies were systematically analyzed. It is found that the position of the power supply point significantly impacts the observational outcomes. The E-SCAN method shows higher resolution in terms of identifying low-resistivity bodies but has limited capability in recognizing high-resistivity bodies. These findings provide a strategic workflow for practical geophysical exploration: rapid anomaly delineation using the E-SCAN method followed by high-precision 3D inversion. Full article

The existing studies on Small-Scale Embedded Generation (SSEG) have not addressed the net billing framework behavior that applies to different import and export tariff rates. This paper presents the simulation and modeling of a smart net billing electricity meter for SSEG in MATLAB/Simulink R2018b. The model integrates a PV array, MPPT controller, DC-DC boost converter, three-phase voltage source inverter (VSI), LC filter, synchronous generator, and a bidirectional energy meter. A smart billing subsystem was developed to compute real-time energy costs using differential tariff rates consistent with South African utility policies. Simulations were conducted under fixed irradiance, with electrical performance evaluated over a short interval and billing dynamics assessed over an extended period. Results show stable PV generation, proper inverter synchronization with the utility grid, and accurate tracking of imported and exported energy. The system effectively calculates the net bill, demonstrating transparency, automation, and economic accuracy in line with policy-driven net billing frameworks. These outcomes validate the technical feasibility and practical relevance of smart net billing meters in modern grid-connected renewable energy applications. Full article

Cascaded H-bridge converters are the prevalent option for classic energy storage converters due to their excellent battery integration and current sharing capabilities. However, this scheme requires numerous IGBT switchings and exhibits high losses in low-voltage, high-power applications due to high current flowing through the batteries. Furthermore, the limited DC voltage regulation capability makes it difficult to obtain sufficient DC voltage for modulation when the battery is continuously discharging, resulting in shortened continuous discharge duration. To address these issues, this paper proposes a novel energy storage converter based on controllable DC buses. The proposed controllable DC bus consists of cascaded half-bridges and a bidirectional DC converter, where the former topology is designed to preserve voltage and current balancing between batteries, as well as boost the DC voltage—thereby reducing the current flowing through the batteries and minimizing losses. The latter topology is implemented to maintain DC bus voltage during battery discharge, thereby increasing the continuous operating time of the proposed energy storage converter. Moreover, the control and modulation of the proposed controllable DC bus have been optimized, and its effectiveness and performance are verified through simulation results. Full article

Thermoelectric generator (TEG)-based energy harvesting (EH) has emerged as a promising solution for powering ultra-low-power electronic systems. However, the inherently low output voltage of miniature TEGs is often below a range of 40–100 mV under small temperature gradients, presenting a fundamental cold-start challenge for DC-DC boost converters, preventing fully autonomous operation without dedicated start-up circuitry. Although numerous start-up techniques have been reported, the existing literature lacks a focused, design-oriented review of circuit architecture specifically optimized for ultra-low-voltage TEG applications. This paper addresses this gap by introducing a unified classification framework and providing a structured, topology-oriented analysis of state-of-the-art start-up strategies for TEG-based EH systems. Reported techniques are organized into five categories: external energy assistance, mechanical switch-assisted techniques, multi-source EH, transformer-based architectures, and oscillator-driven DC-AC-DC conversion. Each category is comparatively evaluated in terms of start-up voltage, integration level, efficiency, and system autonomy. Among these, oscillator-based approaches, particularly ring oscillator (RO) architectures, emerge as the most viable pathway toward fully integrated and scalable implementations, owing to their CMOS compatibility and architectural flexibility. The review further discusses key design trade-offs, handover stability challenges, and practical limitations, and provides architectural insights to guide the development of next-generation autonomous TEG-powered platforms. Full article

This paper presents a voltage compensation algorithm as an addition to the existing improved sorting algorithm for post-fault operation of a modular multilevel converter with integrated batteries, aimed at electric vehicle applications. The work focuses on improving the performance of the sorting algorithm that allows the converter to continue operating without degradation after one transistor fault, by using the faulted module in half-bridge mode while preserving access to its battery. However, the existing sorting algorithm has a limitation during continuous high-power operation, where the faulted module cannot discharge sufficiently. This results in a voltage imbalance between the modules and distortion of the output current waveform. To address this issue, a voltage level compensation algorithm is proposed, which adjusts the module operational limits and the reference signal amplitude based on the measured module voltages. The method compensates the positive and negative half-periods of the output waveform independently, since different modules are active in each half-period during fault conditions. The simulation and experimental results demonstrate that the proposed algorithm compensates the output current successfully, even when the module voltages differ significantly. An FFT analysis confirmed the elimination of the DC offset and the reduction of the low-frequency harmonics, resulting in a total harmonic distortion comparable to normal operating conditions. Full article

Aiming to improve the robustness of two-phase buck converters powering DC bus of permanent magnet synchronous motor drives, this article presents a novel voltage regulation scheme. The proposed scheme comprises a three-switching-surface nonsingular fast terminal sliding mode controller (TSS-NFTSMC) for output voltage regulation and a current balancing controller to equalize the inductor currents. Due to the fast terminal sliding mode surface, the output voltage error converges more rapidly both when far from zero and when approaching zero. The phase plane is split into four regions by three independent switching surfaces. Based on the region where the sliding variable resides, the TSS-NFTSMC can directly decide the number of enabled high-side switches, which helps suppress internal disturbances effectively. The stability and convergence of the presented control system are verified via Lyapunov stability analysis. The convergence property of TSS-NFTSMC is independent of the current controller. Both simulation and experimental results demonstrate that the proposed control strategy achieves satisfactory dynamic response and strong disturbance rejection capability. Full article

The growing use of electric vehicles (EVs) requires fast charging solutions capable of delivering high power levels with greater efficiency and less impact on the power grid. This article presents the design and simulation of a Level 3 fast direct current (DC) charger for electric vehicles based on an LLC resonant DC-DC converter. The proposed architecture incorporates an isolated LLC resonant converter, selected for its soft switching capability, low switching losses, and reduced electromagnetic interference (EMI). The main contribution of this work is the design and simulation of a 50 kW LLC resonant converter developed specifically for a Level 3 DC fast charger for electric vehicles, a power level that, to the authors’ knowledge, has not been previously described in the current scientific literature using this topology. For the proposed converter, it has been proposed to use commercially available wide bandgap (WBG) semiconductor devices specifically made of silicon carbide (SiC). This allows for high switching frequency operation, lower conduction and switching losses, and higher power density. The key design parameters, component selection, and operating principles are analyzed in detail. Simulation results demonstrate high conversion efficiency, reduced switching stress, and stable operation under fast charging conditions, validating the suitability of the LLC topology for high-power electric vehicle charging applications. The proposed system offers a scalable and efficient solution that can contribute to the development of compact, grid-compatible DC fast charging stations, supporting the growing demand for electromobility infrastructure. Full article