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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Adaptive voltage control scheme for DAB based modular cascaded SST in PV application
摘要： Solid state transformer (SST) is able to interface PV panels and distributed grid, which could serve as a new structure for future PV plants. However, the wide operating voltage range of PV system reduces the efficiency of DAB based modular cascaded SST system. Thus, this paper analyzes the impact of DAB voltage deviation between input and output side under frequency component analysis. Besides adjusting primary and secondary side duty cycles, which is widely used in previous literature, this paper utilizes DAB output voltage as an extra control freedom in SST. Then, an adaptive voltage control (AVC) scheme is proposed, which changes DAB output voltage in accordance with input voltage. This paper presents the detailed implementation of AVC and thoroughly compares SST cell efficiency with previous modulation method. Finally, the proposed method is verified in 10kV/1MW SST system.
关键词： SST,DAB,efficiency,Adaptive voltage control
更新于2025-09-23 15:21:01
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Gravitational Physics with Atomic Quantum Sensors
摘要： This paper proposes a practical solution of high-frequency-link dc transformer based on switched capacitor (SCDCT) for medium-voltage dc (MVDC) power distribution application. Compared to the traditional dc transformer scheme, the proposed SCDCT can disconnect from MVDC distribution grid effectively as a dc breaker when a short fault occurs in the distribution, can enhance power transfer capacity, and always ensures high-frequency-link voltage match to improve current impact and ef?ciency performances, and the redundancy design can be achieved when some submodules fail to improve the reliability. In the paper, the topology, voltage and power characterization, control strategy, startup, and fault solution of SCDCT are presented and analyzed comprehensively. At last, an SCDCT prototype is built and the experimental results verify the correctness and effectively of the proposed solution.
关键词： switched capacitor,dc transformer,dc–dc converter,solid-state transformer (SST),DC distribution,high-frequency-link,dual active bridge (DAB)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Thinking Beyond Limiting Efficiencies Of Advanced Concepts: Design Rules And Material Requirements For Realistic Devices
摘要： The current-fed dual active bridge (CF-DAB) dc–dc converter gains growing applications in photovoltaic (PV) and energy storage systems due to its advantages, e.g., a wide input voltage range, a high step-up ratio, a low input current ripple, and a multiport interface capability. In addition, the direct input current controllability and extra control freedom of the CF-DAB converter make it possible to buffer the double-line-frequency energy in grid-interactive PV systems without using electrolytic capacitors in the dc link. Therefore, a PV system achieves high reliability and highly ef?cient maximum power point tracking. This paper studies the optimized operation of a CF-DAB converter for a PV application in order to improve the system ef?ciency. The operating principle and soft-switching conditions over the wide operating range are thoroughly analyzed with phase-shift control and duty-cycle control, and an optimized operating mode is proposed to achieve the minimum root-mean-square transformer current. The proposed operating mode can extend the soft-switching region and reduce the power loss, particularly under a heavy load and a high input voltage. Moreover, the ef?ciency can be further improved with a higher dc-link voltage. A 5-kW hardware prototype was built in the laboratory, and experimental results are provided for veri?cation. This paper provides a design guideline for the CF-DAB converter applied to PV systems, as well as other applications with a wide input voltage variation.
关键词： root-mean-square (RMS) current,photovoltaic (PV),soft switching,optimized operation,Current-fed dual active bridge (CF-DAB)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP) - Le gosier, Guadeloupe (2019.12.15-2019.12.18)] 2019 IEEE 8th International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP) - Hyperspectral Super-Resolution: A Coupled Nonnegative Block-Term Tensor Decomposition Approach
摘要： This paper proposes a grid-tied photovoltaic (PV) system consisting of modular current-fed dual-active-bridge (CF-DAB) dc–dc converter with cascaded multilevel inverter. The proposed converter allows a small dc-link capacitor in the three-phase wye-connected PV system; therefore, the system reliability can be improved by replacing electrolytic capacitors with ?lm capacitors. The low-frequency ripple-free maximum power point tracking (MPPT) is also realized in the proposed converter. First of all, to minimize the in?uence resulting from reduced capacitance, a dc-link voltage synchronizing control is developed. Then, a detailed design of power mitigation control based on CF-DAB dynamic model is presented to prevent the large low-frequency voltage variation propagating from the dc-link to PV side. Finally, a novel variable step-size MPPT algorithm is proposed to ensure not only high MPPT ef?ciency, but also fast maximum power extraction under rapid irradiation change. A downscaled 5-kW PV converter module with a small dc-link capacitor was built in the laboratory with the proposed control and MPPT algorithm, and experimental results are given to validate the converter performance.
关键词： Current-fed dual-active-bridge (CF-DAB),low-frequency ripple,maximum power point tracking (MPPT),small dc-link capacitor,high-frequency link (HFL)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Validation of Advanced Photovoltaic Module Materials and Processes by Combined-Accelerated Stress Testing (C-AST)
摘要： The current-fed dual active bridge (CF-DAB) dc–dc converter gains growing applications in photovoltaic (PV) and energy storage systems due to its advantages, e.g., a wide input voltage range, a high step-up ratio, a low input current ripple, and a multiport interface capability. In addition, the direct input current controllability and extra control freedom of the CF-DAB converter make it possible to buffer the double-line-frequency energy in grid-interactive PV systems without using electrolytic capacitors in the dc link. Therefore, a PV system achieves high reliability and highly ef?cient maximum power point tracking. This paper studies the optimized operation of a CF-DAB converter for a PV application in order to improve the system ef?ciency. The operating principle and soft-switching conditions over the wide operating range are thoroughly analyzed with phase-shift control and duty-cycle control, and an optimized operating mode is proposed to achieve the minimum root-mean-square transformer current. The proposed operating mode can extend the soft-switching region and reduce the power loss, particularly under a heavy load and a high input voltage. Moreover, the ef?ciency can be further improved with a higher dc-link voltage. A 5-kW hardware prototype was built in the laboratory, and experimental results are provided for veri?cation. This paper provides a design guideline for the CF-DAB converter applied to PV systems, as well as other applications with a wide input voltage variation.
关键词： soft switching,optimized operation,Current-fed dual active bridge (CF-DAB),photovoltaic (PV),root-mean-square (RMS) current
更新于2025-09-19 17:13:59
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[IEEE 2019 24th Microoptics Conference (MOC) - Toyama, Japan (2019.11.17-2019.11.20)] 2019 24th Microoptics Conference (MOC) - High-power-output (11 dBm) SOA assisted extended reach EADFB laser (AXEL) for 1.25-Gbit/s high-loss budget optical access networks
摘要： This paper presents the transient dc bias and the current impact effects of a high-frequency-isolated bidirectional dc–dc converter (IBDC) in practice because the theoretical premise in the steady process cannot be satis?ed strictly in the transient process. The transient characterizations of IBDC under the steady phase-shift (SPS) strategy are analyzed comprehensively, and the corresponding model is modi?ed for all of the transient processes in the same and different power ?ows. Due to the existence of the dc bias, the current model in the transient process is different from the traditional model in the steady process, and the models are different with different operating conditions. On this basis, a transient phase-shift (TPS) strategy is proposed to improve the transient performance of the SPS strategy. Unlike in the SPS strategy, the voltages of the transformer are symmetrical in the TPS strategy, which causes that the voltage–time product of the transformer voltages is zero during a switching period, then eliminates the transient dc bias and improves the current impact, and further increases the response speed of the transient process effectively. Finally, comprehensive experiments verify the theoretical analysis.
关键词： high-frequency-link (HFL),Current impact,transient,dc–dc converter,dc bias,dual-active-bridge (DAB),phase-shift (PS)
更新于2025-09-19 17:13:59
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[IEEE 2019 22nd International Conference on Electrical Machines and Systems (ICEMS) - Harbin, China (2019.8.11-2019.8.14)] 2019 22nd International Conference on Electrical Machines and Systems (ICEMS) - The Simulink of a stacked Large-Scale Photovoltaic Power Generation System
摘要： In traditional photovoltaic power generation system, the low voltage side (not more than 1kV) is connected to the inverter through a photovoltaic combiner box, and then delivered the power to the grid through a power frequency transformer. However, the system has high transmission loss, Low penetration of MPPT and high cost. This paper proposes a stacked photovoltaic power generation system structure, where each PV array is input into each bidirectional DC/DC converter independently, and the output side of the bidirectional DC/DC converter is connected in series to the input terminal of the three-phase full-bridge modular multilevel converter, finally achieve to connect the high voltage grid. The work in this paper, a simulation model of 10kV/100kW photovoltaic power generation system is built in MATLAB/Simulink platform, in order to verify the feasibility and reliability of the proposed system structure and control strategy.
关键词： DAB,PV array,Simulation,MMC,MPPT
更新于2025-09-16 10:30:52
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Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion
摘要： Objectives: To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Pro?lometry (CP) measures investigating brushing or dab-on of stannous-?uoride dentifrice on early aggressive dentine erosion. Methods: 75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; arti?cial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-?uoride NaF (2) or stannous-?uoride SnF2 (3), and dab-on application of NaF (4) or SnF2 (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and pro?led using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples. Results: Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p ? 0.01). There were no signi?cant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF2 brushing (3) increased micro-hardness more than control (1) (p ? 0.03), NaF (4) and SnF2 dab-on (5) (p (cid:2) 0.001), and increased surface roughness more than control (p ? 0.02), NaF brushing (2) and NaF dab-on (4) (p (cid:2) 0.017). Dab-on of SnF2 (5) produced rougher surfaces than control (1) (p ? 0.014) and reduced hardness compared with NaF brushing (p ? 0.04). Conclusions: Good agreement and correlation exists between CLSM and CP measures in dentine. There were no signi?cant differences in surface loss after interventions between groups. Compared with control, SnF2 application increased dentine surface roughness and SnF2 controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine. Clinical signi?cance: Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-?uoride brushing, and dab-on application offer no bene?ts following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.
关键词： Prosthetic dentistry,Medical imaging,Dab-on,Mathematical biosciences,Dental materials,Biophysics,Dentistry,Erosion,Measurement,Software engineering,Applied computing in medical science,Abrasion,Dentifrice,Biocomputational method,Dentine-wear
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - The application of cascade power electronic transformer in large-scale photovoltaic power generation system
摘要： In this paper, a high frequency isolated photovoltaic dc side connection system based on dual active bridge (DAB) converter with multiple photovoltaic arrays with parallel input and cascade output is proposed. The power transmission capacity of DAB converter is analyzed, its phase-shifting control strategy is designed, and a 300kW/3kV photovoltaic power generation system model is built in MATLAB/Simulink for simulation. The simulation results verify the feasibility of the system structure and the effectiveness of the proposed control strategy.
关键词： maximum power point tracking (MPPT),PV array,photovoltaic power generation,dual active bridge (DAB)
更新于2025-09-11 14:15:04