Search results for "partial saturation"
showing 8 items of 8 documents
Characterization of inductors in partial saturation for SMPS applications
2017
The exploitation of partially saturated inductors in Switching Mode Power Supply (SMPS) is a key strategy for reducing the size of SMPS and increasing their power density [1]. However an accurate characterization and modellization of each inductor is needed for a correct design and control of the SMPS [2]. Most of inductors' datasheets only indicate the nominal inductance at low current. Anyway, when the inductor is subjected to a higher current, the value of the inductance is lessened. Moreover, inductance meters often actuate their measurements at no or moderate DC bias. In this work we describe the realization of an automated test bench (Fig. 1) for characterizing an inductor under varia…
Hydromechanical behaviour of a volcanic ash
2013
This paper presents experimental analysis and numerical modelling aimed at improved understanding and prediction of the hydromechanical behaviour of volcanic ash at various states of saturation. Results from a comprehensive experimental programme are presented in order to characterise the response of the material in terms of matric suction and confining stress changes. The evolution of the yield stress at different suction levels has been quantified. The volumetric response with suction variations allowed the analysis of the collapse-upon-wetting behaviour. Water retention and permeability are also addressed. Tests results are used to calibrate a constitutive model based on the effective s…
Fabric evolution and the related swelling behaviour of a sand/bentonite mixture upon hydro-chemo-mechanical loadings
2015
This experimental study investigates the swelling behaviour of an 80/20 sand/bentonite mixture and the associated fabric evolution under different hydro-chemo-mechanical loadings. Free and confined swelling tests are performed on specimens compacted to different dry densities and wetted with different pore fluids. Controlled suction confined swelling tests are performed to determine the suction–swelling pressure relationship for two different densities. An extensive microstructural characterisation is performed to relate the observed swelling behaviour to the evolution of the different pore networks during wetting. Based on the microstructural analysis, an expression is proposed to determi…
Characterization of Non-linear Inductors Including Thermal Effects for Power Applications
2018
This paper is focused on the behaviour of non-linear inductors employed in DC/DC switching converters considering the effects due to variations of both current and temperature. The characterization of the inductors is performed by a buck converter operated to stimulate the inductor under test by a constant current with superimposed a large signal. The measurements are carried out at several inductor’s temperature values. Data are automatically collected by a novel virtual instrument developed by the authors in LabVIEW® environment aiming to obtain a polynomial based analytical model. The deep knowledge of the inductor model allows its design to be optimized improving the power density of th…
A Temperature Dependent Non-Linear Inductor Model for a DC/DC Boost Converter
2018
This paper is focused on the use of non-linear inductors in DC/DC switching converters, as well as their behaviour due to changes in current and temperature. The model of an inductor is set up on the basis of experimental data, which are automatically acquired by a virtual instrument; from those data, a polynomial curve describing the inductance variations is obtained. The analysis of the converter, performed by including the proposed model, is validated by experimental tests.
Characterization of inductors in partial saturation including thermal effects for DC/DC converters
2018
Modern switching power electronic converters are widely used in many industrial and consumer applications, especially in step-up and step-down configurations. The optimization of the inductor in the converter design gives advantages in terms of power density increase and cost reduction; therefore, to properly design the converters, it is necessary to improve the knowledge of magnetic material behaviour as the current changes. The development of new models is becoming crucial in the design of modern power converters and there are some recent papers dealing with the use of inductors working in partial saturation [1-5]. This issue is of great interest for scientists and industry due to economi…
Hydro-mechanical analysis of volcanic ash slopes during rainfall
2016
Rainfall-induced landslides in volcanic ashes represent a major natural hazard in many regions around the world. Owing to their loose structure, volcanic ash slopes are prone to rainfall-induced landslides. The paper presents a continuum modelling approach for the analysis of wetting-induced instability phenomena at the onset of failure in loose volcanic ash slopes. A numerical simulation of a landslide-prone volcanic slope in Costa Rica is carried out with a two-dimensional hydro-mechanical finite-element slope model. A constitutive model based on the effective stress concept extended to partially saturated conditions is used to reproduce the volcanic ash hydro-mechanical behaviour. The m…
Water retention behaviour and microstructural evolution of MX-80 bentonite during wetting and drying cycles
2014
MX-80 bentonite used in engineered barrier systems would be subjected to wetting and drying cycles. To assess the response of the material under such circumstances, a comprehensive experimental characterisation of the water retention behaviour of compacted MX-80 granular bentonite was performed in this study. A new methodology is proposed to investigate this behaviour under a constant volume condition for specimens prepared at different dry densities. The material was subjected to different hydraulic paths, including cyclic variations of the water content. As a result, an irreversible modification of the retention behaviour was observed when the material approached a fully saturated state …