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Modeling and simulation are powerful tools to design power distribution systems made up of multiple converters and loads, such as the system of the more-electric aircraft (MEA). However, a system designer usually has no access to detailed data of the power converters, due to confidentiality of manufacturers. Therefore, a black-box modeling approach is necessary. This paper proposes a large-signal black-box modeling technique of three-phase voltage source inverters. The resulting model is oriented to perform system-level analysis and is fully parameterized from the transient response of the converter, which is obtained through simple experimental tests based on low-cost equipment. Moreover, it does not represent the internal data of the converter, thus keeping the confidentiality of the manufacturer. The proposed method has been experimentally validated on a 5-kW actual inverter, which has been applied on the test bench of an MEA power distribution system. [ABSTRACT FROM AUTHOR]

The auxiliary railway power supply (ARPS) is needed in order to provide low and medium voltages to the onboard systems from the catenary high voltage. The outputs of the ARPS can be dc (24\ \Vdc \div 100\ \Vdc) or ac (400\ \Vac). In the case of ac voltage generation, the ac output voltage is under very restrictive total harmonic distortion specifications even in the presence of nonlinear loads which draw low-frequency current harmonics. Along the present paper, a new modulation technique is proposed under the name of harmonic cancellation technique. It is based on the proper pre-distortion of the inverter output voltage in order to generate a controlled fundamental harmonic as well as a set of low-frequency harmonics which cancel out the harmonic pollution due to the nonlinear load performance. The theoretical background needed to implement the modulation technique is provided as well as the experimental validation of the proposed modulation technique through a scale-down prototype. [ABSTRACT FROM AUTHOR]

Today, "black-box" behavioral models of power converters are becoming interesting for system level simulation of power electronics systems. These models can be used to evaluate the response of systems that are composed of commercial converters, since they can be fully parameterized by analyzing the actual converter response. To optimize the required computational resources, these models should be as simple as possible. Furthermore, the identification of the parameters should be carried out easily, looking for simple experiments and straightforward adjusting algorithms. Easy modeling and identification procedures, based on a transient response analysis, are proposed in this paper. Using this method,a large-signal "black-box" behavioral model of a power converter is composed of reduced-order transfer functions, which are identified by analyzing the step response of the converter. Both an actual commercial dc-dc converter and a line-commutated rectifier have been modeled and identified by means of this approach, in order to validate the proposed procedures. [ABSTRACT FROM AUTHOR]

Most of single-stage power factor correction (PFC) ac-dc converters usually present a high voltage swing on the storage capacitor. That means, high size and cost of the storage capacitor is obtained. The Series Inductance Interval (SII) PFC converters allow reducing cost and size of the storage capacitor since the capacitor voltage is lower than the output voltage and, therefore, the voltage swing is significantly reduced. In this paper, the novel single-stage SII-B-2D PFC converter is presented. In addition, this topology provides input current harmonics under EN61000-3-2 Class D limits and advantageous component count. [ABSTRACT FROM AUTHOR]

The fast response double buck (FRDB) dc-dc converter was presented like a low output voltage dc-dc converter with fast transient response, in order to feed devices such as microprocessors and digital signal processors (DSPs). The topology of the FRDB is composed of two buck converters connected in parallel, each one of them with different features and aims, and controlled by means of the novel linear-non-linear (LnL) control. In this paper, the topology, the control strategy and the operation principle are shown. Finally, experimental results in different prototypes are presented to show both, the transient response and the recovery time when these prototypes are subjected to load current steps, and the influence of the output filter on these parameters. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical and experimental study of the hybrid sources capabilities to improve both the dynamic response and the stability of switching power supplies. The hybrid sources are composed by both, a linear and a switching source connected in parallel. The reached improvements have been possible without affecting, significantly, the efficiency of the whole circuit. This solution is checked in low voltage sources. The obtained experimental results show that these power supplies present high dynamical performance, and therefore they can be used to feed digital signal processors and microprocessors. [ABSTRACT FROM AUTHOR]

In this paper, PWM-PD multiple output dc/dc converters are presented. Operation analysis and power block design are shown. Furthermore, a small-signal model is developed for the PWM-PD multiple output dc/dc converters working in continuous conduction mode. The control-block is presented and the closed-loop circuit performances, such as the line, load and cross regulation, are obtained analytically. Finally, experimental results for a PWM-PD converter, with three fully regulated outputs and with transformer, are shown. [ABSTRACT FROM AUTHOR]

This paper develops step-by-step a complete electric model of a light hybrid electric vehicle propulsion system. This model includes the vehicle mass, the radius and mass of the wheels, the aerodynamic profile of the vehicle, the electric motor and the motor drive, among other elements. Each element of the model is represented by a set of equations, which lead to getting an equivalent electric circuit. Based on this model, the outer and inner loop compensators of the motor drive control circuit are designed to provide stability and a fast dynamic response to the system. To achieve this, the steady-state equations and the small-signal model of the equivalent electric circuit are also obtained. Furthermore, as these elements are the main load of the power distribution system of the fully electric and light hybrid electric vehicle, the input impedance model of the set composed of the input filter, the motor drive, the motor, and the vehicle is presented. This input impedance is especially useful to get the system stability of the entire power distribution system. [ABSTRACT FROM AUTHOR]

Aim: To determine prevalence of H pylori infection in symptomatic children in Buenos Aires, Argentina, and to investigate factors associated with H pylori positivity., Methods: A total of 395 children with upper gastrointestinal symptoms referred to the Gastroenterology Unit of the Children Hospital "Sor Maria Ludovica" were evaluated for the presence of H pylori by the (13)C-Urea Breath Test ((13)C-UBT). A questionnaire was applied to the recruited population., Results: Prevalence of H pylori infection was 40.0% in this population (mean age 9.97 +/- 3.1 years). The factors associated with H pylori positivity were number of siblings (P < 0.001), presence of pet cats (P = 0.03) and birds (P = 0.04) in the household, and antecedents of gastritis among family members (P = 0.01). After multivariate analysis, number of siblings [Odds ratio (OR) = 1.39; 95% CI, 1.20-1.61] and contact with pet cats (OR = 1.76; 95% CI, 1.00-3.09) remained as variables associated with H pylori infection., Conclusion: The prevalence of H pylori infection in children with upper gastrointestinal symptoms in Argentina was similar to that reported in developed countries. Children from families with a higher crowding index and presence of pet cats have a higher risk of being colonized with H pylori.