Efficiency Analysis of an Isolated High Voltage Gain Converter Operating in Resonant and Non-Resonant Mode

This paper presents an efficiency investigation of an isolated high step-up ratio dc-dc converter aimed to be used for energy processing from low-voltage high-current energy sources, like batteries, photovoltaic modules or fuel-cells. The considered converter consists of an interleaved active clamp flyback topology combined with a voltage multiplier at the transformer secondary side capable of two different operating modes, i.e. resonant and non-resonant according to the design of the output capacitors. The main goal of this paper is to compare these two operating modes from the component losses point of view with the aim of maximize the overall converter efficiency. The approach is based on losses prediction using steady-state theoretical models (designed in Mathcad environment), taking into account both conduction and switching losses. The models are compared with steady-state simulations and experimental results considering different operating modes to validate the approach

Efficiency analysis of an isolated high voltage gain converter operating in resonant and non-resonant mode

This paper presents an efficiency investigation of an isolated high step-up ratio dc-dc converter aimed to be used for energy processing from low-voltage high-current energy sources, like batteries, photovoltaic modules or fuel-cells. The considered converter consists of an interleaved active clamp flyback topology combined with a voltage multiplier at the transformer secondary side capable of two different operating modes, i.e. resonant and non-resonant according to the design of the output capacitors. The main goal of this paper is to compare these two operating modes from the component losses point of view with the aim of maximize the overall converter efficiency. The approach is based on losses prediction using steady-state theoretical models (designed in Mathcad environment), taking into account both conduction and switching losses. The models are compared with steady-state simulations and experimental results considering different operating modes to validate the approach. © 2012 IEEE

Absorbed Dose to the Skin in Radiological Examinations of Upper and Lower Gastrointestinal Tract

Absorbed doses to the skin in radiological examinations of the upper and lower gastrointestinal tract in conventional and digital radiology are evaluated and compared. Absorbed doses were measured with LiF thermoluminescence dosemeters placed on the lower pelvis, umbilicus and forehead of the patient to evaluate the absorbed dose in and outside the primary beam. On 10 patients a reduction in absorbed dose of about 34% for double contrast barium enema and of 66% for upper gastrointestinal tract examinations was revealed with digital radiography equipment. In our working conditions the lower dose requirement for digital radiography is mainly due to new image intensifiers and television chains and also, due to our equipment settings, to the dose reduction with digital spot fluorography compared with conventional spot film radiography