Selective harmonic elimination in awide modulation range using modified Newton-raphson and pattern generation methods for a multilevel inverter

Considering the aim of having low switching losses, especially in medium-voltage and high-power converters, the pre-programmed pulse width modulation technique is very useful because the generated harmonic content can be known in advance and optimized. Among the different low switching frequency techniques, the Selective Harmonics Elimination (SHE) modulation method is most suitable because of its direct control over the harmonic spectrum. This paper proposes a method for obtaining multiple solutions for selectively eliminating specific harmonics in a wide range of modulation indices by using modified Newton-Raphson (NR) and pattern generation techniques. The different pattern generation and synthesis approach provide more degrees of freedom and a way to operate the converter in a wide range of modulation. The modified Newton-Raphson technique is not complex and ensures fast convergence on a solution. Moreover, multiple solutions are obtained by keeping a very small increase in the modulation index. In the previous methods, solutions were not obtainable at all modulation indices. In this paper, only exact solutions to the low-order harmonics elimination for Cascaded H-bridge inverter are reported for all modulation indices. Analytical and simulation results prove the robustness and correctness of the technique proposed in this paper. 2018 by the authors.Acknowledgments: This (publication, report, etc.) was made possible by NPRP grant # [X-033-2-007] from the Qatar National Research Fund (a member of Qatar Foundation).Scopu

Geographical area network-structural health monitoring utility computing model

In view of intensified disasters and fatalities caused by natural phenomena and geographical expansion, there is a pressing need for a more effective environment logging for a better management and urban planning. This paper proposes a novel utility computing model (UCM) for structural health monitoring (SHM) that would enable dynamic planning of monitoring systems in an efficient and cost-effective manner in form of a SHM geo-informatics system. The proposed UCM consists of networked SHM systems that send geometrical SHM variables to SHM-UCM gateways. Every gateway is routing the data to SHM-UCM servers running a geo-spatial patch health assessment and prediction algorithm. The inputs of the prediction algorithm are geometrical variables, environmental variables, and payloads. The proposed SHM-UCM is unique in terms of its capability to manage heterogeneous SHM resources. This has been tested in a case study on Qatar University (QU) in Doha Qatar, where it looked at where SHM nodes are distributed along with occupancy density in each building. This information was taken from QU routers and zone calculation models and were then compared to ideal SHM system data. Results show the effectiveness of the proposed model in logging and dynamically planning SHM.This publication was made possible by NPRP grant # 8-1781-2-725 from the Qatar National Research Fund (a member of Qatar Foundation). The publication of this article was funded by the Qatar National Library

Symmetric and Asymmetric Multilevel Inverter Topologies With Reduced Device Count

In this work, two new topologies of single-phase hybrid multilevel inverters for symmetrical and asymmetrical configurations are presented for use in drives and control of electrical machines and the connection of renewable energy sources. The proposed topology uses 2 dc sources, 12 switches, 1 flying capacitor, and 3 diodes to generate boosted 13-levels and 17-levels for symmetric and asymmetric configuration, respectively. Self-voltage balancing of its capacitor voltage regardless of load type, load dynamics, or modulation index is a key advantage of the suggested design. The higher performance of proposed topologies in terms of the total number of switches, TSV, THD, switch stress, and dc sources are demonstrated by comparing those with recently published topologies. In addition, a widely employed nearest level control modulation approach is used to provide output voltage levels with low THD. Finally, experiments were undertaken to validate the performance of the suggested topology. 2013 IEEE.This work was supported in part by Qatar University Research Grant from Qatar University, Doha, Qatar, under Grant QUCP-CENG-2020-2 and Grant QUCP-CENG-2022-571; and in part by the Qatar National Library, Doha.Scopu

Performance Analysis of a Three-to-Five Phase Dual Matrix Converter Based on Space Vector Pulse Width Modulation

In this paper, space vector pulse width modulation (SVPWM)-based algorithms for a five-phase open-end load fed from dual matrix converter (DMC) have been proposed. In the presented modulation methods, the reference output voltage vector is synthesized from two three-to-five phase matrix converters at both the ends of the load. Depending on the power-sharing of the two MCs, two proposed modulation methods are defined as equal reference sharing (ERS) and unequal reference sharing (URS). The performance of ERS and URS for the three-to-five phase DMC drive is compared. Performance comparison is based on the total harmonic distortion in the output voltages and the percentage of the voltage transferred from the source to the load, for the full linear modulation index (MI) range. Common mode voltage and zero sequence current in the load are also discussed. The efficiency of the ERS and URS is compared. It has been observed that the proposed ERS scheme offers better performance compared with URS for most of the MI values. The suggested modulation techniques are implemented in MATLAB/Simulink. The hardware setup is developed and control algorithm is implemented using dSPACE working in conjunction with the FPGA interface board for practical validation

Design and Sensitivity Analysis of Dynamic Wireless Chargers for Efficient Energy Transfer

Tunable Self-Oscillating Switching (TSOS) methods are a robust solution for tuning of Inductive Power Transfer (IPT) systems. However, they require deep analysis to be an appropriate choice for Dynamic Wireless Charging (DWC) systems. In this paper, the optimal operation point of TSOS in the maximum power transfer, efficiency, and Zero Voltage Switching (ZVS) realization perspectives are determined based on sensitivity analysis for DWC of Electric Vehicles (EVs). In the sensitivity analysis, all the possible states of the coupling factor and state of charge (SOC) are considered as system variables. Moreover, a new phasor modeling for constant voltage (battery) loads is proposed. The performance of this model is quite different from the conventional static model for the loads. Moreover, to limit the current of the charger under light couplings, a simple hysteresis controller is employed. A setpoint is proposed based on the sensitivity analysis method to transfer maximum energy in misaligned conditions. The proposed setpoint increases transferred energy and energy efficiency while limits the current of the charger. To analyze this method, simulation is done in the Simulink/MATLAB, and to verify the results, a laboratory prototype is implemented.This publication was made possible by Qatar University Collaborative Research grant # [QUCG-CENG-19/20-5] from the Qatar University. The statements made herein are solely the responsibility of the authors. The APC is funded by the Qatar National Library, Doha, Qatar.Scopu

Fintech and contactless payment: Help or hindrance? The role of invasion of privacy and information disclosure

Purpose: There is always a need to discover how a paradox between a customer’s desire for a more personalized experience and their privacy and security concerns would shape their intention to continue using contactless payment methods. However, personalization–privacy paradox has not been well-covered over the area of contactless payment. Therefore, this study aims to empirically examine the impact of personalization–privacy paradox on the customers’ continued intention (CIN) to use contactless payment. Design: /methodology/approach – The empirical part of the current study was conducted in Saudi Arabia by collecting the primary data using online questionnaire from a convenience sample size of 297 actual users of contactless payment methods. Findings: Based on structural equation modeling, personalization and privacy invasion were approved to significantly impact perceived value of information disclosure (PVD). Strong causal associations were confirmed between perceived severity, structural assurance and response cost with privacy invasion. Finally, both PVD and privacy invasion significantly predict CIN. : There are other important factors (i.e. technology interactivity, technology readiness, social influence, trust, prior experience, etc.) were not tested in the current study. Therefore, future studies would pay more attention regarding the impact of these factors. The current study data were also collected using a convenience sample of actual users of contactless payment methods. Therefore, there is a concern regarding the generalizability of the current study results to other kind of customers who have not used contactless payment. Originality/value: This study has integrated both personalization–privacy paradox and protection motivation theory in one model. The current study holds value in providing a new and complete picture of the inhibitors and enablers of customers’ CIN to use contactless payment, including new types of inhibitors. Furthermore, personalization–privacy paradox has not been fully examined over the related area of Fintech and contactless payment in general. Therefore, this study was able to extend the theoretical horizon personalization–privacy paradox to new area (i.e. contactless payment) and new cultural context (Saudi Arabia)

Small-Signal Stability Analysis and Parameters Optimization of Virtual Synchronous Generator for Low-Inertia Power System

The stable operation of converter-interfaced generation (CIG) units is paramount for ensuring resilience in low-inertia power systems. This paper presents a comprehensive small-signal modeling and stability analysis framework for grid-connected virtual synchronous generators (VSGs), integrating: an LCL-filter interfaced power converter, active/reactive power loop (APL/RPL) controllers, and dual-loop PI-based current and voltage control. Through systematic eigenvalue analysis and parameter sensitivity studies, complemented by time-domain verification in MATLAB/SIMULINK, we demonstrate the decisive influence of VSG control parameters on low-frequency oscillation (LFO) damping characteristics, transient frequency stability metrics, including the rate of change of frequency (ROCOF), maximum frequency deviation (fnadir), overshoot, and settling time. We further propose a hybrid Particle Swarm Optimization (PSO) algorithm with a multi-objective cost function to optimize VSG controller gains. The optimized design achieves an 83% reduction in ROCOF, a 90% improvement in frequency deviation, and a non-oscillatory power response. These results quantitatively validate that proper VSG gain tuning can significantly enhance dynamic performance and frequency stability in inertia-constrained grids. The proposed methodology offers practical insights for designing resilient CIG-dominated power systems.Qatar University and Iberdrola S.A. as part of its Innovation Department Research Studies (Grant Number: QUEX-CENG-IBERDROLA-22/23 and QUEX-CENG-IBERDROLA-IDC). Qatar National Library through Open Access Funding

Triple boost switched capacitor multilevel inverter (TB-SCMLI) with reduced components and self-voltage balance

Multi-level inverter (MLIs) designs with switched-capacitor (SC) are on the rise due to their applicability in sustainable energy systems and high voltage applications. In this light, this paper presents a compact triple-boost switched-capacitor multilevel inverter (TB-SCMLI) topology with fewer switches and self-voltage balancing capacitors. Large spikes appear in the source current and charging currents of switched-capacitors as a result of the charging and discharging actions of the switched capacitors. In order to suppress the spikes in the source and charging currents of switched-capacitors, the proposed converter incorporates a soft switching circuit. The soft charging circuit consists of an inductor and a diode in the charging path of the proposed converter to ensure soft charging of the switched-capacitors. By inserting a small value of inductance in the soft charging circuit, the proposed converter can significantly suppress source current spikes. The proposed TB-SCMLI is able to provide seven levels of output voltage by balancing the voltage of two capacitors with the given control logic. The various SCMLIs are evaluated to determine the contribution of the suggested TB-SCMLI topology's merits and downsides. To validate the performance of the proposed TB-SCMLI, comprehensive experimental findings under various laboratory test settings have been given.This work was supported in part by Qatar univsersity Research Grant from Qatar University, Doha, Qatar, Under Grant: QUCP-CENG-2022-571. The statement made herein are solely the responsibility of the authors. The APC for this manuscript is funded by the Qatar National Library, Doha, Qatar.Scopu

Influence of alternating temperature preculture on cryopreservation results for potato shoot tips

Cryopreservation is the most suitable long-term storage method for genetic resources of vegetatively maintained crops like potato. In the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) the DMSO droplet method is applied, and so far more than 1000 accessions are cryopreserved with an average regeneration rate of 58%. New experiments with four potato accessions using alternating temperatures (22/8°C day/night temperature, 8 h photoperiod, 7 d) prior to cryopreservation showed improved regeneration. The influence of this preculture on the shoot tips was studied for two wild, frost resistant species Solanum acaule and S. demissum and for two cultivated, frost sensitive potatoes S. tuberosum ‘Désirée’ and ‘King Edward’. Comparison of liquid and solid media after cryopreservation showed improved regeneration on solid media with higher regeneration percentages, less callus formation and better plantlet structure. In comparative analyses biochemical factors like soluble sugars, starch, and amino acid concentrations were measured. Shoot tips after constant and after alternating temperature preculture were analyzed. Total concentrations of soluble sugars (glucose, fructose, and sucrose) were higher for all accessions after the alternating temperature preculture, which could be the reason for improved cryopreservation results