scholarly journals Design and Experimental Verification of 400-WClass LED Driver with Cooperative Control Method for Two-Parallel Connected DC/DC Converters

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2237 ◽  
Author(s):  
Tomoharu Yada ◽  
Yuta Katamoto ◽  
Hiroaki Yamada ◽  
Toshihiko Tanaka ◽  
Masayuki Okamoto ◽  
...  
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Experimental Verification ◽  
Control Strategy ◽  
Cooperative Control ◽  
Control Method ◽  
Power Conversion ◽  
Switching Frequency ◽  
Frequency Method ◽  
Led Driver

This paper deals with a design and experimental verification of 400-W class light-emitting diode (LED) driver with cooperative control method for two-parallel connected DC/DC converters. In the cooperative control method, one DC/DC converter is selected to supply the output current for the LED, based on the reference value of the LED current. Thus, the proposed cooperative-control strategy achieves wide dimming range operation. The discontinuous current conduction mode (DCM) operation improves the total harmonic distortion (THD) value on the AC side of the LED driver. The standard of Electrical Applications and Materials Safety Act in Japan has defined the flicker frequency and minimum optical output. The smoothing capacitors are designed by considering the power flow and LED current ripple for satisfying the standard. A prototype LED driver is constructed and tested. Experimental results demonstrate that a wide dimming operation range from 1 to 100% is achieved with a THD value less than 10% on the AC side, by the proposed control strategy. The authors compare the power conversion efficiency between Si- and SiC-metal-oxide-semiconductor field-effect transistors (MOSFETs) based LED driver. The maximum power conversion efficiency by using SiC-MOSFETs based LED driver is 91.4%. Finally, the variable switching frequency method is proposed for improving the power conversion efficiency for a low LED current region.

Observer-Based Power Management for Multi-Source Electric Vehicles Using Optimized Splitting Ratios

2018 ◽  
Author(s):  
Ahmed M. Ali ◽  
Dirk Söffker
Keyword(s):  
Power Conversion Efficiency ◽  
Real Time ◽  
Power Management ◽  
Conversion Efficiency ◽  
Electric Vehicles ◽  
Control Method ◽  
Power Conversion ◽  
Observer Design ◽  
Power Handling ◽  
Optimal Power

Optimal power management in real-time is a core technology of hybrid electric vehicles (HEVs). The online application of optimized power split ratios based on driver demand is a promising approach allowing near optimal power handling decisions in real-time. However, the fulfillment of exact power delivery (driveability) is an open challenge of this approach due to interpolation of driver’s demand to the optimized discrete solutions. Finding balanced power management that handles unscheduled loads and sustains required power conversion efficiency may significantly improve the experimental application of this approach. This work proposes an observer-based control method integrated to the power management system that ensures better driveability with minimal effect on power handling optimality. Modeling of traction system for observer design is based on a simplified brushless DC motor model. Identification of system parameters is achieved by a newly introduced error minimization algorithm using NSGA-II to obtain the same dynamic response as the original system. Results analysis shows 7% reduction of power consumption and 98% improvement of driveability at minimal mitigation of power conversion efficiency.

scholarly journals Miniature DC-DC Boost Converter for Driving Display Panel of Notebook Computer

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2924
Author(s):  
Seok-Hyeong Ham ◽  
Hyung-Jin Choe
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Power Conversion ◽  
Input Voltage ◽  
Boost Converter ◽  
Switching Frequency ◽  
Notebook Computer ◽  
Switching Losses ◽  
Voltage Stress ◽  
Switch Temperature

This paper proposes a miniature DC-DC boost converter to drive the display panel of a notebook computer. To reduce the size of the circuit, the converter was designed to operate at a switching frequency of 1 MHz. The power conversion efficiency improved using a passive snubber circuit that consisted of one inductor, two capacitors, and two diodes; it reduced the switching losses by lowering the voltage stress of the switch and increased the voltage gain using charge pumping operations. An experimental converter was fabricated at 2.5 cm × 1 cm size using small components, and tested at input voltage 5 V ≤ VIN ≤ 17.5 V and output current 30 mA ≤ IO ≤ 150 mA. Compared to existing boost converters, the proposed converter had ~7.8% higher power conversion efficiency over the entire range of VIN and IO, only ~50% as much voltage stress of the switch and diodes, and a much lower switch temperature TSW = 49.5 °C. These results indicate that the proposed converter is a strong candidate for driving the display panel of a notebook computer.

scholarly journals Optimization of Charge Pump Based on Piecewise Modeling of Output-Voltage Ripple

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4809
Author(s):  
Yajun Lin ◽  
Jianxin Yang ◽  
Tin-Wai Mui ◽  
Yong Zhou ◽  
Ka-Nang Leung
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Output Voltage ◽  
Power Conversion ◽  
Charge Pump ◽  
Switching Frequency ◽  
Linear Charge ◽  
Voltage Ripple ◽  
Accurate Design ◽  
Charge Pump Circuit

This work proposes a piecewise modeling of output-voltage ripple for linear charge pumps. The proposed modeling can obtain a more accurate design expression of power-conversion efficiency. The relationship between flying and output capacitance, as well as switching frequency and optimize power-conversion efficiency can be calculated. The proposed modeling is applied to three charge-pump circuits: 1-stage linear charge pump, dual-branch 1-stage linear charge pump and 4× cross-coupled charge pump. Circuit-level simulation is used to verify the accuracy of proposed modeling.

scholarly journals Performance Improvement of PWM Control Methods for Voltage Step-Down in Series Resonant DC–DC Converters

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4569
Author(s):  
Vadim Sidorov ◽  
Andrii Chub ◽  
Dmitri Vinnikov
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Pulse Width Modulation ◽  
Renewable Energy Sources ◽  
Power Conversion ◽  
Input Voltage ◽  
Voltage Regulation ◽  
Switching Frequency ◽  
Semiconductor Switches ◽  
Series Resonant

The paper is focused on galvanically isolated series resonant DC–DC converters (SRCs) with a low quality factor of the resonant tank. These converters provide input voltage regulation at fixed switching frequency and good power density. Different modulation methods at the fixed switching frequency enable the implementation of the voltage buck functionality in these converters. The SRC under study is considered as a step-up front-end DC–DC converter for the integration of renewable energy sources in DC microgrids. The paper evaluates the voltage buck performance of the SRC achieved by using different pulse-width modulation (PWM) methods including conventional PWM and shifted PWM. Moreover, the new PWM methods, i.e., the hybrid shifted PWM (HSPWM), improved shifted PWM (ISPWM), and hybrid PWM (HPWM), are proposed to overcome the disadvantages of the existing methods. They improve the power conversion efficiency in the buck mode by reducing the power losses in the semiconductor switches and the isolating transformer of the SRC. The proposed and the existing methods are benchmarked in terms of the components stresses and power conversion efficiency. The presented findings have been experimentally validated by the help of a 200 W prototype, which demonstrated the lowest power loss in the case of the HPWM.

scholarly journals Numerical analysis with experimental verification to predict outdoor power conversion efficiency of inverted organic solar devices

2019 ◽  
Vol 135 ◽  
pp. 589-596 ◽  
Author(s):  
Kai Jeat Hong ◽  
Sin Tee Tan ◽  
Kok-Keong Chong ◽  
Chi Chin Yap ◽  
Mohammad Hafizuddin Hj Jumali ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Experimental Verification ◽  
Power Conversion

scholarly journals A Comprehensive Overview in Control Algorithms for High Switching-Frequency LLC Resonant Converter

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4455
Author(s):  
Hwa-Pyeong Park ◽  
Mina Kim ◽  
Jee-Hoon Jung
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
High Power ◽  
Power Conversion ◽  
Voltage Regulation ◽  
Control Algorithms ◽  
Switching Frequency ◽  
Resonant Converter ◽  
High Switching Frequency ◽  
Llc Resonant Converter

An LLC resonant converter has been widely used in various industrial applications because of its high cost-effectiveness, high power conversion efficiency, simple design methodology, and simple control algorithms using a pulse frequency modulation (PFM). In addition, the soft switching capability of the LLC resonant converter is good to obtain high switching frequency operations, which can get the high-power density of the power converter. Over the past years, several studies have been conducted to improve the performance of a high switching frequency LLC resonant converter with resonant tank design, optimal power stage design, and enhanced control algorithms. This paper is the review paper in terms of the control algorithms for the LLC resonant converter. It focuses on the overview of the high switching-frequency LLC resonant converter in terms of the control algorithms. The advanced control algorithm can improve power conversion efficiency, dynamic performance, tight output voltage regulation, and small electro-magnetic interference. The operational principles of the control algorithms are briefly explained to show their own characteristics and advantages. Thereafter, the research issues for the future works will be discussed in the conclusion.

A thiourea additive-based quadruple cation lead halide perovskite with an ultra-large grain size for efficient perovskite solar cells

Nanoscale ◽  
2019 ◽  
Vol 11 (45) ◽  
pp. 21824-21833 ◽  
Author(s):  
Jyoti V. Patil ◽  
Sawanta S. Mali ◽  
Chang Kook Hong
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Inorganic Perovskite ◽  
Halide Perovskite ◽  
Lead Halide

Controlling the grain size of the organic–inorganic perovskite thin films using thiourea additives now crossing 2 μm size with >20% power conversion efficiency.

The Effect of Donor Molecular Structure on Power Conversion Efficiency of Small-Molecule-Based Organic Solar Cells

2019 ◽  
Vol 16 (3) ◽  
pp. 236-243 ◽  
Author(s):  
Hui Zhang ◽  
Yibing Ma ◽  
Youyi Sun ◽  
Jialei Liu ◽  
Yaqing Liu ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Small Molecule ◽  
Organic Solar Cells ◽  
Molecular Design ◽  
Power Conversion ◽  
The Relationship

In this review, small-molecule donors for application in organic solar cells reported in the last three years are highlighted. Especially, the effect of donor molecular structure on power conversion efficiency of organic solar cells is reported in detail. Furthermore, the mechanism is proposed and discussed for explaining the relationship between structure and power conversion efficiency. These results and discussions draw some rules for rational donor molecular design, which is very important for further improving the power conversion efficiency of organic solar cells based on the small-molecule donor.

Enhanced efficacy of defect passivation and charge extraction for efficient perovskite photovoltaics with a small open circuit voltage loss

2019 ◽  
Vol 7 (15) ◽  
pp. 9025-9033 ◽  
Author(s):  
Jin-Feng Liao ◽  
Wu-Qiang Wu ◽  
Jun-Xing Zhong ◽  
Yong Jiang ◽  
Lianzhou Wang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Power Conversion ◽  
Charge Recombination ◽  
Open Circuit ◽  
Polymeric Semiconductor ◽  
Voltage Loss ◽  
Defect Passivation

A multifunctional 2D polymeric semiconductor was incorporated to provide surprisingly robust efficacy in grain boundary functionalization and defect passivation of perovskite, which suppresses charge recombination and thus affording an illustrious photovoltage of 1.16 V and power conversion efficiency of 21.1%.

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