Non-Linear Inductor Models Comparison for Switched-Mode Power Supplies Applications

The use of non-linear power inductors, intended as devices exploited up to a current at which the inductance is halved, is of great interest in switched-mode power supplies (SMPSs). Indeed, it allows the use of lighter and cheaper inductors improving the power density. On the other hand, the analysis of SMPSs equipped with non-linear inductors requires appropriate modeling of the inductor reproducing the inductance versus current. This paper compares two main analytical models proposed in the literature: the former is based on a polynomial, and the latter exploits the arctangent function to reproduce the non-linearity of the inductance. Performance is compared by considering the effort of r…

Density of States evaluation of Molybdenum Oxide for c-Si solar cell

Silicon-based heterojunction technology (HJT) is one of the most promising candidates for high performance and low cost solar cells with world-record efficiency close to 27% in IBC architecture. The HJT exploits the excellent passivation properties of hydrogenated amorphous silicon (a-Si:H); although, the use of doped a-Si:H has drawbacks such as parasitic absorption and low-thermal budget to cope with back-end metallization. Replacing the p-type a-Si:H with molybdenum oxide (MoOx) is a viable alternative. Optimizing this hole-selective layer is needed; however information on the defect density of states (DOS), linked to oxygen vacancies is still lacking.

Metallization of Si heterojunction solar cell by Cu electroplating

In response to recent climate change, many renewable energy solutions have acquired great importance; in fact, the need of sustainable development is increasing and the use of renewable energy, such as solar energy, can be applied to many industrial and consumer applications. Photovoltaic systems, which are made up of solar cells, are used for electrical vehicle charging stations and to supply remote areas not connected to the power distribution network; moreover, solar energy is widely used as a primary or secondary source of domestic electric power. In this scenario, the increasing in efficiency, and the cost reduction of solar cells, becomes a priority in the diffusion of PV systems for …

NON-LINEAR INDUCTOR CONTRIBUTION TO HARMONIC SPECTRUM IN POWER CONVERTERS

The paper investigates the harmonic content in DC/DC power converters where the inductor is operated in the non-linear region. This operation is often exploited to use lighter and cheaper inductors; as a drawback, an increasing number of harmonics is noticeable. A theoretical analysis is proposed. It is based on a polynomial model of the inductor used in a boost converter. Results are given by the spectra of the output voltage performed on a circuit prototype.

Characterization of inductors in partial saturation including thermal effects for DC/DC converters

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…

Assessment of the Current for a Non-Linear Power Inductor Including Temperature in DC-DC Converters

A method for estimating the current flowing through a non-linear power inductor operating in a DC/DC converter is proposed. The knowledge of such current, that cannot be calculated in closed form as for the linear inductor, is crucial for the design of the converter. The proposed method is based on a third-order polynomial model of the inductor, already developed by the authors; it is exploited to solve the differential equation of the inductor and to implement a flux model in a circuit simulator. The method allows the estimation of the current up to saturation, intended as the point at which the differential inductance is reduced to half of its maximum value. The current profile depends al…

Self-Heating Induced Instability of a Non-Linear Inductor in a SMPS: a Case Study

This paper proposes a case study to show that the non-linear operation of a power inductor in a SMPS can induce instability of the control system leading to overheating of the inductor beyond its allowable temperature and to an excessive peak of the maximum current. The case study is performed by a commercial ferrite inductor employed in a synchronous boost converter encompassing a control system to adjust the duty cycle, assuring a constant output voltage. The thermal transient is described by the time domain waveforms and thermal images.

Density of States characterization of TiO2 films deposited by Pulsed Laser Deposition for Heterojunction solar cells

The application of titanium dioxide (TiO2) in the photovoltaic field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact. For modeling-based optimization of such contact, knowledge of the titanium oxide defect density of states is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band …

Non-Linear Inductors Characterization in Real Operating Conditions for Power Density Optimization in SMPS

The exploitation of power inductors outside their linear region in switching converters can be achieved by raising the current until a decreasing of the inductance can be noticed. It allows using a smaller magnetic core increasing the power density of the converter. On the other hand, a detailed description of the magnetization curve including the temperature is required. Since this information is often not included in the inductor’s datasheets, this paper shows how to identify the behavior of an inductor when it is operated up to saturation and its temperature rises. In order to characterize the inductor in real operating conditions, a dedicated measurement rig has been developed. It consi…

Erratum to: Sub-gap defect density characterization of molybdenum oxide: An annealing study for solar cell applications

Comparison between SiC and GaN switching devices in fast-recharging systems for electric vehicles

Recently, the improvement of the semiconductor devices to achieve higher efficiency and higher power density has risen to interest. Si carbide and gallium nitride offer faster switching frequency and lower losses; however, the knowledge of the behaviour of these devices is not mature. In this paper, a system for fast charging of batteries for electric vehicles based on an isolated DC-DC converter equipped with both SiC and GaN devices is presented and an interesting experimental comparison among these two technologies will be given in terms of dynamic performances, electromagnetic compatibility, stability, efficiency, and so on.