The Experts below are selected from a list of 75411 Experts worldwide ranked by ideXlab platform
F C Lee - One of the best experts on this subject based on the ideXlab platform.
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a high efficiency single stage single switch high power factor ac dc converter with universal input
IEEE Transactions on Power Electronics, 1998Co-Authors: Jinrong Qian, F C LeeAbstract:A single-stage single-switch power-factor-correction (PFC) AC/DC converter with universal input is presented in this paper. The PFC can be achieved based upon the charge-pump concept, and the PFC stage operates in the continuous current mode (CCM). The switch has less current and voltage stresses over a wide range of Load Variation so that a low-voltage rating device can be used. The presented converter features high power factor, high efficiency, and low cost. An 80-W prototype was implemented to show that it has 85% efficiency with low-voltage stress from 0.5% to 100% Load Variation over universal line input.
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a high efficient single stage single switch high power factor ac dc converter with universal input
Applied Power Electronics Conference, 1997Co-Authors: Jinrong Qian, F C LeeAbstract:A single stage single switch high power factor correction AC/DC converter with universal input is presented in this paper. The high power factor can be achieved based upon the charge pump concept and power factor correction stage operating in the continuous current mode. The switch has no current and voltage stresses over a wide range of Load Variation so that a low voltage rating device can be used. The presented converter has features of high power factor, high efficiency, and low cost. An 80-watt prototype was implemented to show that it has 85% higher efficiency with no voltage stress from 0.5% to 100% Load Variation over universal line input.
Jinrong Qian - One of the best experts on this subject based on the ideXlab platform.
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a high efficiency single stage single switch high power factor ac dc converter with universal input
IEEE Transactions on Power Electronics, 1998Co-Authors: Jinrong Qian, F C LeeAbstract:A single-stage single-switch power-factor-correction (PFC) AC/DC converter with universal input is presented in this paper. The PFC can be achieved based upon the charge-pump concept, and the PFC stage operates in the continuous current mode (CCM). The switch has less current and voltage stresses over a wide range of Load Variation so that a low-voltage rating device can be used. The presented converter features high power factor, high efficiency, and low cost. An 80-W prototype was implemented to show that it has 85% efficiency with low-voltage stress from 0.5% to 100% Load Variation over universal line input.
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a high efficient single stage single switch high power factor ac dc converter with universal input
Applied Power Electronics Conference, 1997Co-Authors: Jinrong Qian, F C LeeAbstract:A single stage single switch high power factor correction AC/DC converter with universal input is presented in this paper. The high power factor can be achieved based upon the charge pump concept and power factor correction stage operating in the continuous current mode. The switch has no current and voltage stresses over a wide range of Load Variation so that a low voltage rating device can be used. The presented converter has features of high power factor, high efficiency, and low cost. An 80-watt prototype was implemented to show that it has 85% higher efficiency with no voltage stress from 0.5% to 100% Load Variation over universal line input.
Saad Mekhilef - One of the best experts on this subject based on the ideXlab platform.
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improved differential evolution based mppt algorithm using sepic for pv systems under partial shading conditions and Load Variation
IEEE Transactions on Industrial Informatics, 2018Co-Authors: Kok Soo Tey, Saad Mekhilef, Mehdi Seyedmahmoudia, E Hora, Ale StojcevskiAbstract:Photovoltaic arrays subject to partial shading conditions have more than one maximum power point (MPP), and conventional algorithms are unable to track the global maximum power point (GMPP) accurately. Thus, an improved global search space differential evolution algorithm for tracking the GMPP is introduced in this paper. The main contribution of the proposed algorithm are the following: capability in tracking GMPP and faster respond against Load Variation; optimization algorithm can search for the GMPP within a larger operating region as it is implemented by using a single-ended primary-inductor converter; and easy tuning as less parameter has to be set in the algorithm. The proposed system is first simulated in PSIM to ensure its capability. The feasibility of the approach is validated through physical implementation and experimentation. Results demonstrate that the proposed algorithm has the capability to track the GMPP within 2 s with an accuracy of 99% and respond to Load Variation within 0.1 s.
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modified incremental conductance algorithm for photovoltaic system under partial shading conditions and Load Variation
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Kok Soon Tey, Saad MekhilefAbstract:Under partial shading conditions, multiple peaks are observed in the power-voltage (P- V) characteristic curve of a photovoltaic (PV) array, and the conventional maximum power point tracking (MPPT) algorithms may fail to track the global maximum power point (GMPP). Therefore, this paper proposes a modified incremental conductance (Inc Cond) algorithm that is able to track the GMPP under partial shading conditions and Load Variation. A novel algorithm is introduced to modulate the duty cycle of the dc-dc converter in order to ensure fast MPPT process. Simulation and hardware implementation are carried out to evaluate the effectiveness of the proposed algorithm under partial shading and Load Variation. The results show that the proposed algorithm is able to track the GMPP accurately under different types of partial shading conditions, and the response during Variation of Load and solar irradiation are faster than the conventional Inc Cond algorithm. Hence, the effectiveness of the proposed algorithm under partial shading condition and Load Variation is validated in this paper.
Sewan Choi - One of the best experts on this subject based on the ideXlab platform.
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a fully soft switched single switch isolated dc dc converter
IEEE Transactions on Power Electronics, 2015Co-Authors: Minjae Kim, Sewan ChoiAbstract:This paper proposes a soft-switched single switch isolated converter. The proposed converter is able to offer low cost and high power density in step-up application due to the following features: zero-current switching (ZCS) turn-on and zero-voltage switching (ZVS) turn-off of switch and ZCS turn-off of diodes regardless of voltage and Load Variation; low rated lossless snubber; reduced transformer volume compared to flyback-based converters due to low magnetizing current. Experimental results on a 100 kHz, 250 W prototype are provided to validate the proposed concept.
Han Ho Song - One of the best experts on this subject based on the ideXlab platform.
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experimental and computational study on the dynamic interaction between Load Variation and back pressure control in a polymer electrolyte membrane fuel cell for automotive application
International Journal of Hydrogen Energy, 2015Co-Authors: Dongkyu Kim, Jae Seon Koh, Minsoo Kim, Han Ho SongAbstract:Abstract Experimental and computational study on the operating characteristics of the fuel cell with changing back pressure at the cathode and anode outlets was performed for both steady and transient operations. In the experiments, the back pressure was controlled by a pressure regulator in the fuel cell outlet, and the effects of the operating pressure under various Load conditions were observed in steady-state operations. The transient responses of the fuel cell to the Load changes in different operating pressures were also examined. Additionally, in order to fully understand the effects of the major parameters in various operating pressures on the fuel cell performance, a dynamic simulation model of the cell stack was developed. The performance analysis revealed that a higher voltage was produced by the cell when a high pressure was maintained because the high pressure facilitated high concentration of the reactant gas near the membrane. The mass flow rate of the liquid water also increased with increasing pressure in a given humidity, which helped to maintain higher voltage than otherwise. However, the overshoot and undershoot of the output voltage during Load transition also increased with increasing back pressure, primarily because of the difference between the rates of gas supply to the membrane and gas consumption near the membrane. Whereas the consumption of the gas near the membrane was rapid, the fresh reactant gas required some time to reach the membrane. The inherent time lag resulted in undershoot and overshoot with changing Load. It was observed that the remaining liquid water was also an important factor which affected the level of undershoot or overshoot during the Load change. Finally, an operating strategy using a back-pressure regulator was suggested and applied in a transient operation of irregular multi-step Load Variation. The back pressure should be decreased before the Load change and restored back to the pre-set level for the steady-operation. The former was shown to reduce the size of undershoot or overshoot during transition, and the latter could lead to the efficient operation by reducing parasitic losses in the fuel cell system.
