Search Results (191)

This paper proposes a single-stage common-ground series-capacitor-compensated buck–boost inverter (CG-SCC-BBI) for wide-input DC–AC applications. Featuring a common-ground neutral and a series-blocking film capacitor, the topology inherently suppresses high-frequency common-mode leakage-current excitation and blocks the structural DC offset. To counteract frequency-dependent voltage attenuation caused by the output network, a fundamental-frequency equivalent model is derived to pre-scale the modulation reference and fully restore output voltage amplitude. The four-switch power stage operates with single-active-leg PWM, confining high-frequency switching to a single half-bridge at any instant to significantly reduce the switching-loss budget. Furthermore, by eliminating the conventional line-frequency output filter choke and utilizing film capacitors exclusively, the topology completely avoids electrolytic capacitors, thereby enhancing long-term operational reliability and lifespan. The proposed inverter supports seamless transition between boost and buck operating modes across the entire input-voltage range. Its operating principles are validated through time-domain simulations, and these were experimentally verified on a 300 W SiC MOSFET standalone laboratory prototype. Experimental results confirm correct operation from 95 V to 400 V DC input, achieving maximum measured efficiencies of 96.79% at the rated 300 W under low-input operation and 97.66% at the rated 300 W under high-input operation, while maintaining an output-current total harmonic distortion (THD) below 2.5%. Full article

The paper presents an analytical study and small-signal modeling of a non-inverting two-switch buck–boost converter based on the LM5118 controller, accounting for parasitic elements. The converter dynamics were analyzed using simulations in the PLECS^® 5.0.2 environment. Furthermore, the steady-state and dynamic characteristics of the LM5118-based two-switch buck–boost converter were examined using the PSpice for TI^® simulator for different input voltages and load conditions. The obtained simulation results show close correspondence with the analytical analysis, confirming the validity of the proposed approach. Full article

Various inverter applications such as electronic vehicles, renewable energy systems, and uninterrupted power supplies have been the motive behind the increasing focus on the DC-AC inverters field. Therefore, DC-AC inverters have been evolving with the recent topology being the Z-source inverters (ZSIs). Though the ZSI overcame most of the limitations faced by the previous topologies such as the Voltage-Source Inverters (VSIs) and Current-Source Inverters (CSIs), they had shortcomings such as the increase in switching devices’ voltage stress and hence the deterioration of power quality with the increase in the boost factor. As a result, several ZSI-based topologies have been proposed in the literature to further improve the performance of a ZSI. This paper also proposes a different Z-source inverter topology called the Shunt Capacitor-Boosted Z-Source Inverter (SCB-ZSI) which seeks to improve the boost factor and lower the voltage stress. This inverter strategically adds two shunt capacitors on the impedance network of a traditional Z-source inverter, hence the Shunt Capacitor-Boosted-ZSI. The SCB-ZSI was mathematically modeled and simulated on MATLAB Simulink R2024a version. The SCB-ZSI was found to have a high boost factor compared to the ZSI for the same input DC voltage and modulation index. The SCB-ZSI was also found to incur less switching voltage stress across the switching devices compared to the ZSI for the same input DC voltage and modulation index. The simulation test results showed that the selection of shunt capacitors of a ZSI at 1% of those of the original ZSI improves the boost factor by 56% and reduces the switch voltage stress ration by 40% on an SCB-ZSI for the same set of input parameters. Though the SCB-ZSI is one of the promising ZSI-based inverter topologies, more work still has to be done before they can be industrially applied, such as developing an algorithm to design the shunt capacitors. Full article

Grid-connected photovoltaic (PV) systems paired with battery storage are becoming a core element of low-carbon distribution networks. This paper develops a complete closed-form formulation together with an independent, simulation-based verification of a single-phase grid-connected PV-battery microgrid sized for high-irradiance residential conditions in Saudi Arabia, using measured solar-resource and tariff data for Riyadh. A 6.25 kW monocrystalline array feeds a 400 V DC link through a perturb-and-observe boost stage; a bidirectional converter couples a 13.5 kWh LiFePO₄ battery; and an IEEE 1547 smart inverter interfaces a 230 V grid through an LCL filter. Governing equations for every subsystem are derived and evaluated numerically, and a Python re-implementation of the phasor power-flow model verifies the analysis over a 24 h cycle run to periodic steady state, reproducing the reference design values with a mean absolute error of 0.5%. Using measured monthly solar-resource and temperature data for Riyadh, a full twelve-month analysis gives an annual self-sufficiency of 51.8% and a PV self-consumption of 72.9% for the optimised energy-management scheme. A dedicated time-domain switching simulation with FFT analysis shows that the LCL filter limits grid-current total harmonic distortion to 0.8%, far below the L-filter value of 6.2% and below the 5% current-distortion reference of IEEE 519 (full compliance additionally requires the PCC short-circuit ratio). Twelve-month, battery-size and load-sensitivity studies confirm robustness, and a techno-economic assessment based on the Saudi Electricity Company residential tariff quantifies levelized cost, payback and battery degradation, showing that economic viability hinges on tariff reform. Full article

Background: Despite the circulation of evolutionarily related cold-causing coronaviruses (CCCs) in the pre-COVID era, most individuals lacked pre-existing serum IgG and/or class-switched memory B cell (B_mem) reactivity for the SARS-CoV-2 Spike (S) glycoprotein expressed by the ancestral Wuhan-Hu-1 (WH1) strain. Subsequent priming of the immune system through natural infection or prophylactic COVID-19 mRNA vaccination successfully generated robust B_mem responses against the WH1-S antigen, along with eliciting cross-reactivity for the future Omicron (BA.1) variant responsible for breakthrough infections (BTIs). However, to what extent immunological imprinting of B_mem towards the WH1-S antigen detrimentally constrains the elicitation of variant-specific antibody responses following subsequent booster vaccinations or BTIs—a phenomena referred to as “original antigenic sin”—remains an unresolved and open question. Methods: Using ImmunoSpot^®, we evaluated peripheral blood mononuclear cells (PBMCs) from defined human cohorts for IgG⁺ ASC reactivity against Spike proteins representing CCCs and SARS-CoV-2. Additionally, we developed a novel dual-label inverted FluoroSpot assay to distinguish between strain-specific and cross-reactive IgG⁺ ASCs recognizing epitopes in the receptor binding domain (RBD) of SARS-CoV-2 Omicron variants. Results: Our data demonstrate a lack of appreciable back-boosting of IgG⁺ B_mem recognizing structurally conserved epitopes shared between CCCs and SARS-CoV-2. Moreover, we found evidence for immunological imprinting and the preferential expansion of B_mem recognizing cross-reactive epitopes in the RBD following BTI. Nevertheless, Omicron strain-specific B_mem were detected in PBMC donors collected in 2025. Conclusions: Our novel inverted dual-label FluoroSpot methodology evidenced preferential expansion of cross-reactive B_mem following breakthrough SARS-CoV-2 infection and supports the influence of original antigenic sin shaping the recall response. Moreover, the inverted dual-label assay provides a highly flexible and easily implementable technique for distinguishing between strain-specific and cross-reactive B cell responses and has broad applications in translational vaccine research against pathogens that undergo antigenic drift. Full article

This study addresses the power dispatching of a DC-coupled three-phase grid-connected photovoltaic (PV) and energy storage-integrated system by proposing a peak shaving and valley-filling control architecture based on time-of-use (TOU) pricing. This research involves achieving maximum power-point tracking (MPPT) for PVMAs using a boost converter combined with the perturb and observe (P&O) method. A lithium-iron phosphate battery pack is integrated into the DC link via a bidirectional buck-boost converter, where charging and discharging control is executed according to peak and off-peak periods to regulate and stabilize the DC link voltage. Furthermore, bidirectional power flow control for peak and off-peak electricity consumption is realized using hysteresis current control and sinusoidal pulse-width modulation (SPWM) technologies within a smart inverter. By integrating the aforementioned power control architecture, the grid system can store energy from the utility during off-peak hours and release the stored energy during peak hours to reduce the load demand on the utility side. Initially, a simulation environment was established using Matlab/Simulink (2024b version) software, followed by control verification of the proposed system on a physical platform. The simulation and experimental results confirm that the integrated control architecture can precisely control the system’s DC link voltage at 800 V and stabilize the grid-connected AC voltage at an effective value (RMS) of 380 V. Moreover, under conditions of peak/off-peak switching and load variations, the system effectively demonstrates its stability and efficacy in performing valley filling and peak shaving. The proposed strategy achieves a power factor above 0.99 and a total harmonic distortion (THD) below 5%, regulates the DC-link voltage at 800 V with a steady-state error within 1.75%, and prevents up to 66.4 kWh of over-contract energy consumption per day under a 35 kW contract capacity, thereby contributing to sustainable energy management and economic savings. Full article

Z-source inverters (ZSIs) provide single-stage power conversion with inherent voltage boost capability through shoot-through (ST) states achieved using specialized PWM methods. This study compares various ST PWM strategies, Simple Boost PWM, Maximum Boost PWM, Constant Boost Third Harmonic Injection PWM, and Space Vector PWM, for high-voltage boost ZSI (HVB-ZSI) applications. A MATLAB/Simulink 2024a model was developed to assess their performance in terms of output-voltage quality, THD, capacitor-voltage stress, switch stress, and inductor–current ripple. Results indicate that while all techniques enable ST operation effectively, their voltage stress and harmonic performance differ notably, guiding optimal PWM selection for advanced ZSI-based systems. Full article

Solar photovoltaic (PV)-powered electric vehicles (EVs) have gained greater significance in the present-day era of transportation across the globe. This proposed work presents an analysis of a five-level reduced switched-capacitor multilevel inverter (RSC-MLI)-powered permanent magnet synchronous motor (PMSM) drive for solar PV-powered battery vehicles enabled by a rat swarm optimization (RSO) maximum power point tracking (MPPT) control mechanism. The system proposed in this paper integrates solar PV arrays and battery storage systems for efficient power transfer to EVs for propulsion. In order to achieve fast, accurate tracking of the optimal maximum power point, the RSO technique is used. A five-level RSC-MLI is used in this study, which enables boosting the voltage and lowering switching losses in the system. The performance of the PMSM is further analyzed to obtain constant parameters, such as the velocity and torque of the electric vehicle. Full article

To address the issues of low fundamental content in the output voltage of high-frequency inverters within wireless power transfer (WPT) systems and efficiency degradation caused by coupling coefficients and load variations, this paper proposes a novel seven-level inverter topology and a closed-loop PI control strategy based on current amplitude ratio. First, the influence of LCC-S WPT system parameters on current and efficiency is analyzed. Subsequently, by comparing fundamental content in inverter output voltage across different level structures, a seven-level configuration is selected. A novel seven-level inverter topology with fewer switches and lower voltage stress is proposed, and its efficiency enhancement advantage is validated through optimized switch turn-on angles. Finally, a closed-loop PI control strategy based on current amplitude ratio is adopted. By merely acquiring coil currents and calculating their amplitude ratio, the duty cycle of the Buck-Boost circuit is adjusted to optimize current amplitude, achieving maximum efficiency tracking for the system. Experimental results demonstrate that system efficiency approaches theoretical calculations during coil spacing variations. When the load varies between 5 Ω and 105 Ω, system efficiency remains around 91.4%, with maximum efficiency point tracking error maintained at approximately 2%. This validates the system’s reliability and the effectiveness of the control strategy. Full article

In the context of power electronic interfaces in photovoltaic (PV), fuel cell, battery, and microgrid applications, the low output voltage of the DC source necessitates a voltage-boosting inverter. This paper proposes a single-source seven-level switched-capacitor boost inverter, particularly for low-voltage applications. The proposed inverter has the capability to produce seven different output voltage levels, i.e., intermediate boosted levels, with a total gain of three times the input voltage. The inverter has the advantage of a reduced number of power switches, diodes, and a switched-capacitor unit, which allows for single-stage operation without the need for a second DC-DC converter. The operating principle of the proposed inverter is explained in detail with a complete switching state analysis, conduction path analysis, and output voltage generation. The capacitor size is calculated using a charge balance-based equation. The self-balancing capability is validated for mismatched initial voltages with a bounded steady-state ripple. To evaluate the performance of the proposed inverter in a more realistic scenario, the effects of non-ideal device characteristics are considered, and the efficiency of the inverter is estimated using a loss model. A predictive current control technique is applied to control the output current under inductive load conditions. The simulation results obtained in MATLAB/Simulink software validate the proper seven-level operation of the inverter, the self-balancing capability of the capacitors, improved output waveform quality, and current control. The proposed inverter can be extended to grid-connected applications, where conventional output filters can be applied to meet the harmonic standards. Full article

The integration of renewable energy sources, including photovoltaic (PV) and fuel cell (FC) systems, into AC grids has attracted immense research interest in recent times. Furthermore, incorporating these renewable sources of energy into medium-voltage grids is garnering increased attention because of the obvious benefits of medium-voltage integration at elevated power levels. Photovoltaic applications entail the arrangement of solar panels capable of outputting voltages up to 1.5 kV; nonetheless, fuel cells display restricted output voltage, with a maximum market range of 400 to 700 V. Hence, the efficient integration of renewable energy sources into low-voltage or medium-voltage grids demands the utilization of a step-up direct current (DC–DC) inverter and a converter for connection to the alternating current (AC) grid, in which an efficient step-up converter is critical for the medium-voltage grid. Therefore, this study presents a three-phase buck-boost split-source inverter (BSSI) that resolves the constrained output voltage of the fuel cells. This study focuses on modifying the configuration of a conventional three-phase split-source inverter (SSI) circuit by adding a few components while maintaining the inverter’s modulation. This novel circuit design enables the reduction in voltage strains on the inverter switch components and improves DC-link use in relation to a traditional SSI configuration. For an 800 bus, maximal voltage stress on the primary inverter switches is lowered when compared with the standard SSI that delivers entire DC-bus voltage to switches. A rectifier-based model is employed to simulate the behavior of a renewable energy source. Combining these advantages with the conventional modulation of the inverter offers a more effective design. The buck-boost split-source inverter (BSSI) was analyzed using three distinct modulation techniques: the sinusoidal pulse-width modulation scheme (SPWM), the third-harmonic injected pulse-width modulation (THPWM) scheme, and space vector modulation (SVM). The proposed analysis was validated through MATLAB-SIMULINK and practical outcomes on a 5.0 kW model. The practical and SIMULINK data were found to be closely aligned with the analysis. The circuit developed in this study also ensures efficient DC-to-AC conversion, specifically with regard to low-voltage sources, like fuel cells or photovoltaic (PV) systems. Full article

The transition to clean photovoltaic sustainable generation sources has motivated several developments in required power electronics interface systems. The conventional solution is based on two cascaded conversion stages, leading to reduced efficiency, inevitable leakage currents, and/or a high number of required components. Another solution is the use of integrated two-stage solutions suffering from asymmetrical switch structures, discontinuous input side currents, and/or complex modulation and control requirements. This paper presents a modified configuration with symmetrical six switches based on the common ground boost inverter solution. Furthermore, the proposed solution presents a continuous input side current and a simple modulation strategy. Moreover, the proposed CG topology offers a reduction of the current stress on the power switch by diverting the load current away from the power switch during the inductor charging. The operation, modulation, and control of the developed solution are presented in the paper, including comprehensive performance comparisons with boost inverter solutions in the literature. Simulation and experimental prototype-based results confirm the advantages and superiority of the proposed topology over existing topologies. Full article

This paper proposes a dynamic voltage restorer (DVR) based on a new three-phase multilevel inverter (MLI). An integral component of DVRs is the power electronic converter. At medium-to-high voltage levels, MLIs are the ideal converters for DVR applications because lower voltage-rated switches are used to generate high voltages, thus minimizing power losses. The proposed three-phase MLI generates 15 levels of load voltage per phase, using a reduced component count: eight lower-rated semiconductor power switches, four primary DC voltage sources, two auxiliary DC sources, and eight driver circuits per phase. Additionally, each phase features a low-frequency transformer with voltage-boosting and galvanic isolation capabilities. The switching sequence of the proposed MLI is simpler to execute using fundamental frequency control; this methodology provides reduced switching stress and reduced switching losses as merits. Structurally, the proposed MLI is less complex and thus scalable. The proposed DVR, based on three-phase MLI, efficiently offsets power quality problems such as voltage swell, voltage sags, and harmonics for balanced and unbalanced loads. The operational performance of the proposed DVR-MLI is verified by a simulation, using PSCAD software and an experimental prototype. Full article

Wide-bandgap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) are key enablers of power-electronics converters for aerospace platforms, where high efficiency, weight reduction, and thermal robustness are critical requirements. This paper presents the main challenges associated with the use of these technologies, including protection requirements, electromagnetic compatibility, and thermal management, as well as the material advantages that enable higher switching frequencies and lower losses compared to conventional Si technologies. A comparative analysis of semiconductor technologies and suitable power-conversion topologies for the aerospace context is provided. Representative laboratory-scale experimental validation is presented, including the development of a DC–DC boost converter and a DC–AC full-bridge inverter, which are linked through the common DC-link and are used for interfacing batteries and an electrical motor, both based on GaN and SiC diodes. The results demonstrated the correct operation, with stable high-frequency performance under controlled laboratory conditions, supporting aerospace-oriented development, although evaluated in a laboratory environment, confirming the potential of WBG technologies for future power-conversion architectures. Full article

The output voltages of photovoltaic panels typically fluctuate due to variations in environmental conditions, and therefore the use of a buck–boost inverter is essential. This article presents a novel buck–boost voltage-source inverter topology. The proposed inverter is transformerless and thus is smaller and lower-cost than isolated topologies. The topology consists of four switches but only two of them operate at a high switching frequency during each half-cycle, which significantly reduces switching losses and improves efficiency. Furthermore, a common-ground connection between the inverter input and output effectively suppresses leakage current by mitigating the common-mode voltage issue. The modulation strategy, circuit operation, and design guidelines are presented in detail. Simulation and experimental results at 500 W are also provided to verify the effectiveness of the proposed inverter topology. Full article