scholarly journals Impact of Transformer Turns Ratio on the Power Losses and Efficiency of the Wide Range Isolated Buck–Boost Converter for Photovoltaic Applications

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5645
Author(s):  
Hamed Mashinchi Maheri ◽  
Dmitri Vinnikov ◽  
Andrii Chub ◽  
Vadim Sidorov ◽  
Elizaveta Liivik
Keyword(s):  
High Efficiency ◽  
Input Voltage ◽  
Power Losses ◽  
Efficient Operation ◽  
Wide Range ◽  
Photovoltaic Applications ◽  
Theoretical Predictions ◽  
Converter Topology ◽  
Isolation Transformer ◽  
The Impact

In this paper, the impact of transformer turns ratio on the performance of the quasi-Z-source galvanically isolated DC-DC converters is studied. Embedded buck–boost functionality enables these converters to regulate the input voltage and load in a wide range, which makes them suitable for such demanding application as photovoltaic microconverters. The isolation transformer here plays a central role as its turns ratio defines the point of transition between the boost and buck modes and overall capability of the converter to regulate the input voltage in a wide range at high efficiency. The studied quasi-Z-source galvanically isolated DC-DC converter is benchmarked in terms of power loss of components and weighted power conversion efficiency for three different turns ratios of isolation transformer to achieve the best and optimized turns ratio lead to the efficient operation. Operation in a wide range of input voltage at high efficiency is the main criterion for assessing the effect of turns ratio on the efficiency of the converter. The proposed loss model and theoretical predictions of the efficiency were validated with the help of a 300 W experimental prototype of the photovoltaic microconverter based on the quasi-Z-source galvanically isolated DC-DC converter topology.

A Stable Mode-Selectable Oscillator with Variable Duty Cycle and High-Efficiency

2015 ◽  
Vol 24 (09) ◽  
pp. 1550132 ◽  
Author(s):  
Li-Ye Cheng ◽  
Xin-Quan Lai
Keyword(s):  
Duty Cycle ◽  
High Efficiency ◽  
Dynamic Performance ◽  
Operation Mode ◽  
Charge Pump ◽  
Input Voltage ◽  
Cmos Process ◽  
Pump Efficiency ◽  
Stable Mode ◽  
Wide Range

A mode-selectable oscillator (OSC) with variable duty cycle for improved charge pump efficiency is proposed in this paper. The novel OSC adjusts its duty cycle according to the operation mode of the charge pump, thus improves the charge-pump efficiency and dynamic performance. The control of variable duty cycle is implemented in digital logic hence it provides robust noise immunity and instantaneous response. The OSC and the charge-pump have been implemented in a 0.6-μm 40-V CMOS process. Experimental results show that the peak efficiency is 92.7% at 200-mA load, the recovery time is less than 25 μs and load transient is 15 mV under 500-mA load variation. The system is able to work under a wide range of input voltage (V IN ) in all modes with low EMI.

Self-Cleaning Solar Mirrors Using Electrodynamic Dust Shield: Prospects and Progress

2014 ◽  
Author(s):  
Malay K. Mazumder ◽  
Mark N. Horenstein ◽  
Jeremy W. Stark ◽  
John N. Hudelson ◽  
Arash Sayyah ◽  
...  
Keyword(s):  
Power Generation ◽  
Particle Size ◽  
High Efficiency ◽  
Solar Collectors ◽  
Parabolic Trough ◽  
Atmospheric Dust ◽  
Efficient Operation ◽  
Dust Layer ◽  
Wide Range ◽  
Self Cleaning

Parabolic trough and power tower technologies provide inherent advantage of thermal energy storage and high efficiency of the Concentrating Solar Power (CSP) systems for utility scale solar plants. High efficiency CSP power generation with minimal water use is one of the SunShot goals of the US Department of Energy. The specular reflectance efficiency of the solar mirrors plays a critical role in the efficiency of power generation. The optical surface of the mirrors and the receiver must be kept clean for efficient operation of the plant. Some environmental challenges in operating the large-scale CSP plants at high reflectance efficiency arise from high concentration of atmospheric dust, wind speed and variation of relative humidity (RH) over a wide range. Deposited dust and other contaminant particles, such as soot, salt, and organic particulate matters attenuate solar radiation by scattering and absorption. Adhesion of these particles on the mirror surface depends strongly by their composition and the moisture content in the atmosphere. Presence of soluble inorganic and organic salts cause corrosion of the mirror unless the contaminants are cleaned frequently. In this paper, we briefly review (1) source of atmospheric dust and mechanisms involved in degradation of mirrors caused by salt particles, (2) loss of specular reflection efficiency as a function of particle size distribution and composition, and (3) an emerging technology for removing dust layer by using thin transparent electrodynamic screen (EDS). Feasibility of integration of EDS on the front surface of the solar collectors has been established to provide active self-cleaning properties for parabolic trough and heliostat reflectors. Prototype EDS-integrated solar collectors including second-surface glass mirrors, metallized acrylic film mirrors, and dielectric mirrors, were produced and tested in an environmental test chambers simulating desert atmospheres. The test results show that frequent removal of dust layer can maintain the specular reflectivity of the mirrors above 90% under dust deposition at a rate ranging from 0 to 10 g/m2, with particle size varying from 1 to 50 μm in diameter. The energy required for removing the dust layer from the solar was less than 10 Wh/m2 per cleaning cycle. EDS based cleaning could therefore be automated and performed as frequently as needed to maintain reflection efficiency above 90% and thus reducing water usage for cleaning mirrors in the solar field. A comparative cost analysis was performed between EDS and deluge water based cleaning that shows the EDS method is commercially viable and would meet water conservation needs.

Review and comparison of high efficiency high power boost DC/DC converters for photovoltaic applications

2011 ◽  
Vol 59 (4) ◽  
pp. 499-506 ◽  
Author(s):  
J. Dawidziuk
Keyword(s):  
High Power ◽  
High Efficiency ◽  
State Of The Art ◽  
Environmental Issues ◽  
Switching Frequency ◽  
Power Losses ◽  
Renewable Energy Systems ◽  
Boost Converters ◽  
Power Mosfets ◽  
Photovoltaic Applications

Review and comparison of high efficiency high power boost DC/DC converters for photovoltaic applicationsRecent environmental issues have accelerated the use of more efficient and energy saving technologies in renewable energy systems. High power high efficiency boost DC/DC converters for the use in photovoltaic, fuel cell systems are discussed in this paper from the viewpoint of power losses and efficiency. State of the art converters with switching frequency within the range of 25 kHz with IGBTs to 100 kHz with power MOSFETs and the highest efficiency close to 98%, depending on the load conditions, is considered. A comparison and discussion of the highest efficiency high power DC/DC boost converters is also presented in this paper.

scholarly journals A Structure-Reconfigurable Soft-Switching DC-DC Converter for Wide-Range Applications

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2905 ◽  
Author(s):  
Xianxu Huo ◽  
Ke Xu ◽  
Ruixin Liu ◽  
Xi Chen ◽  
Zhanchun Li ◽  
...  
Keyword(s):  
Direct Current ◽  
High Efficiency ◽  
Zero Point ◽  
Input Voltage ◽  
Optimal Switching ◽  
Peak Efficiency ◽  
Loss Analysis ◽  
Wide Range ◽  
Analysis Calculation ◽  
Current Converter

In this paper, a structure-reconfigurable resonant DC-DC (direct current – direct current) converter is presented. By controlling the state of the auxiliary switch, the converter could change the resonant structure to acquire a high efficiency and wide voltage gain range simultaneously. The characteristics of the LLC (inductor-inductor-capacitor) resonant converter are firstly analyzed. Based on this, through introducing additional resonant elements and adopting the topology morphing method, the proposed converter can be formed. Moreover, a novel parameter selection method is discussed to satisfy both working states. Then, a detailed loss analysis calculation is conducted to determine the optimal switching point. In addition, an extra resonant zero point is generated by the topology itself, and the inherent over-current protection is guaranteed. Finally, a 500 W prototype is built to demonstrate the theoretical rationality. The output voltage is constant at 400 V even if the input voltage varies from 160 to 400 V. A peak efficiency of 97.2% is achieved.

scholarly journals Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1991 ◽  
Author(s):  
Krzysztof Górecki ◽  
Kalina Detka
Keyword(s):  
Nanocrystalline Material ◽  
Input Voltage ◽  
Load Resistance ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Power Losses ◽  
Boost Converters ◽  
The Core ◽  
Operation Conditions ◽  
Wide Range

The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters.

The impact of hybridization, engine combustion method, and energy management system connectivity on heavy-duty vehicle operation

2021 ◽  
pp. 095440702098304
Author(s):  
Carrie M Hall
Keyword(s):  
Real Time ◽  
Energy Management ◽  
High Efficiency ◽  
Fuel Efficiency ◽  
Vehicle Speed ◽  
Heavy Duty ◽  
Wide Range ◽  
Engine Combustion ◽  
The Impact ◽  
Heavy Duty Vehicles

A wide range of strategies for reducing energy consumption from heavy-duty vehicles have been explored from vehicle electrification to real-time vehicle energy management based on vehicle-to-vehicle and vehicle-to-infrastructure communication. Full electrification of heavy-duty vehicles can be challenging due to current limitations on battery energy density. However, hybridization and the implementation of high efficiency engines present other potential near-term solutions. In contrast to many prior studies that have explored the use of one or two of these techniques, this work discusses the combined influence of hybridization level, engine combustion mode, and connected energy management on fuel efficiency in heavy-duty applications. The impact of hybridization in different driving conditions is quantified and the effectiveness of hybrid powertrain structures with different engine combustion strategies is also explored. Utilizing an alternative combustion strategy can improve fuel efficiency by 5% in conventional and mild hybrids but was found to have a more minimal impact in full hybrids. An additional layer of complexity is also introduced when vehicles have some degree of connectivity and this influence on the energy management method is investigated by comparing control approaches which leverage current and future vehicle speed information. Connectivity and the ability to optimize energy production in real-time was found to be essential in uncertain cases and enable improvements in fuel consumption of up to 12% over baseline cases.

scholarly journals Wide-Range Operation of High Step-Up DC-DC Converters with Multimode Rectifiers

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 914
Author(s):  
Andrii Chub ◽  
Dmitri Vinnikov ◽  
Oleksandr Korkh ◽  
Tanel Jalakas ◽  
Galina Demidova
Keyword(s):  
Duty Cycle ◽  
Input Voltage ◽  
Voltage Range ◽  
Front End ◽  
Wide Range ◽  
Theoretical Predictions

This paper discusses the essence and application specifics of the multimode rectifiers in high step-up DC-DC converters. It presents an overview of existing multimode rectifiers. Their use enables operation in the wide input voltage range needed in highly demanding applications. Owing to the rectifier mode changes, the converter duty cycle can be restricted to a range with a favorable efficiency. It is shown that the performance of such converters depends on the front-end inverter type. The study considers current- and impedance-source front-end topologies, as they are the most relevant in high step-up applications. It is explained why the full- and half-bridge implementations provide essentially different performances. Unlike the half-bridge, the full-bridge implementation shows step changes in efficiency during the rectifier mode changes, which could compromise the long-term reliability of the converter. The theoretical predictions are corroborated by experimental examples to compare performance with different boost front-end inverters.

scholarly journals A Comparative Analysis of Half-Bridge LLC Resonant Converters Using Si and SiC MOSFETs

2021 ◽  
Vol 12 (1) ◽  
pp. 43
Author(s):  
Hasaan Farooq ◽  
Hassan Abdullah Khalid ◽  
Waleed Ali ◽  
Ismail Shahid
Keyword(s):  
Silicon Carbide ◽  
Renewable Energy ◽  
High Frequency ◽  
High Efficiency ◽  
Low Voltage ◽  
Low Cost ◽  
Renewable Energy Sources ◽  
Input Voltage ◽  
Resonant Converters ◽  
Wide Range

With the expansion of renewable energy sources worldwide, the need for developing more economical and more efficient converters that can operate on a high frequency with minimal switching and conduction losses has been increased. In power electronic converters, achieving high efficiency is one of the most challenging targets to achieve. The utilization of wideband switches can achieve this goal but add additional cost to the system. LLC resonant converters are widely used in different applications of renewable energy systems, i.e., PV, wind, hydro and geothermal, etc. This type of converter has more benefits than the other converters such as high electrical isolation, high power density, low EMI, and high efficiency. In this paper, a comparison between silicon carbide (SiC) MOSFET and silicon (Si) MOSFET switches was made, by considering a 3KW half-bridge LLC converter with a wide range of input voltage. The switching losses and conduction losses were analyzed through mathematical calculations, and their authenticity was validated with the help of software simulations in PSIM. The results show that silicon carbide (SiC) MOSFETs can work more efficiently, as compared with silicon (Si) MOSFETs in high-frequency power applications. However, in low-voltage and low-power applications, Si MOSFETs are still preferable due to their low-cost advantage.

An Experimental and Numerical Study of a Hydrogen Fueled, Directly Injected, Heavy Duty Engine at Knock-Limited Conditions

2020 ◽  
Author(s):  
Joel Mortimer ◽  
Stephen Yoannidis ◽  
Farzad Poursadegh ◽  
Zhewen Lu ◽  
Michael Brear ◽  
...  
Keyword(s):  
High Efficiency ◽  
Numerical Study ◽  
Engine Performance ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Ignition Timing ◽  
High Compression Ratio ◽  
Combustion Modeling ◽  
Wide Range ◽  
The Impact

Abstract This paper presents an experimental and numerical study of a directly injected, spark-ignited (DI SI), heavy duty hydrogen fueled engine at knock-limited conditions. The impact of air-fuel ratio and ignition timing on engine performance is first investigated experimentally. Two-zone combustion modeling of the hydrogen fueled cylinder is then used to infer burn profiles and unburned, end-gas conditions using the measured in-cylinder pressure traces. Simulation of the autoignition chemistry in this end-gas is then undertaken to identify key parameters that are likely to impact knock-limited behavior. The experiments demonstrate knock-limited performance on this high compression ratio engine over a wide range of air-fuel ratios, λ. Other trends with λ are qualitatively similar to those shown in previous studies of hydrogen fueled engines. Kinetic simulations then suggest that some plausible combination of residual nitric oxide from previous cycles and locally high charge temperatures at intake valve closing can lead to autoignition at the knock-limited conditions identified in the experiments. This prompts a parametric study that shows how increased λ makes hydrogen less likely to autoignite, and suggests options for the design of high efficiency, directly injected, hydrogen fueled engines.

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