Novel control techniques in multiphase drives: direct control methods (DTC and MPC) under limit situations.

Premio Extraordinario de Doctorado U

Assessment of a Universal Reconfiguration-less Control Approach in Open-Phase Fault Operation for Multiphase Drives

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Di erent nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control (MPC), have been used in recent times to govern these complex systems, including mandatory control reconfiguration to guarantee the fault tolerance characteristic. A new reconfiguration-less approach based on virtual voltage vectors (VVs) was recently proposed for MPC, providing a natural healthy and faulty closed-loop regulation of a particular asymmetrical six-phase drive. This work validates the interest in the reconfiguration-less approach for direct controllers and multiphase drives

Incidencia de la Informalidad Laboral en la Productividad Laboral de Nicaragua

Este documento tiene como objeto de estudio la informalidad laboral en los años 2001-2015. Su importancia reside en otorgar un mejor conocimiento de la informalidad laboral y su relación con la productividad laboral en el periodo seleccionado, a su vez, permitirá una correcta implementación de políticas económicas que fomenten un crecimiento sostenible a largo plazo basado en el empleo formal. El presente estudio surge de la necesidad de información acerca de la informalidad laboral en nuestro país. El tipo de análisis utilizado se caracteriza por ser de carácter paramétrico, obteniendo el nivel de significancia de cada variable a través de regresiones lineales, es por esto, que el método implementado para abordar el problema se considera novedoso debido a las pocas investigaciones realizadas en el país de este tipo. La investigación se cataloga de carácter exploratoria ya que es el primer trabajo de este tipo. A su vez, se considera descriptiva ya que medirá y recogerá información sobre los conceptos y variables necesarias para el estudio. El fundamento teórico de este estudio se encuentra en la teoría de la informalidad laboral institucionalista, la cual establece que la informalidad laboral es el resultado de un análisis costo-beneficio por parte de los trabajadores. El objetivo general de esta investigación es realizar una comprobación empírica de la informalidad laboral y su afectación en el crecimiento económico del país. El poco acceso a los datos necesarios es una de las más grandes limitaciones a las que se enfrentan los investigadores que pretenden profundizarse aún más en este tema. Lo hipótesis planteada anticipa que la productividad laboral demostrada en el país es afectada por la gran cantidad de empleo informal. En el segundo capítulo se realizara una caracterización del mercado laboral Nicaragüense en el cual se evaluara el desempeño del Producto Interno Bruto a través del enfoque del gasto y las variables Inflación, Empleo Formal, desempleo y Balanza Comercial. En el tercer capítulo se seleccionan y evalúan las variables que se consideran determinantes en la reducción de la informalidad en el país. Por último se abordara la creación de la variable dependiente para la elaboración del modelo econométrico que se utilizara para medir el efecto que tiene la informalidad laboral sobre la productividad laboral. También se realizaran las pruebas necesarias para determinar si el modelo es válido

Field Oriented Control of Multiphase Drives with Passive Fault-Tolerance

Multiphase machines provide continuous operation of the drive with no additional hardware in the event of one or more open-phase faults. This faulttolerant capability is highly appreciated by industry for security and economic reasons. However, the steadystate post-fault operation has only been feasible in previous works after the fault localization and control reconfiguration. Even though this is done at the software stage, the obligation to identify the faulty phases and store the modifications for every fault scenario adds further complexity. This work reveals that this software reconfiguration can be avoided if the field-oriented control (FOC) strategy is designed to satisfactorily handle pre- and post-fault situations. Experimental results confirm the capability to obtain suitable postfault operation without fault localization and control reconfiguration, thus achieving a passive/natural fault tolerance.Ministerio de Ciencia, Innovación y Universidades RTI2018-096151-B-I0

Impact of post-fault flux adaptation on six-phase induction motor drives with parallel converters

The redundancy of multiphase drives provides an inherent fault-tolerant capability that is appreciated in applications with a complicated corrective maintenance or safety-critical requirements. Fault restrictions however force the system to be reconfigured to operate in a smooth and efficient manner. Previous works have been focused on the optimization of current waveforms to generate an undisturbed operation but still maintaining the pre-fault rated flux settings. This work shows that efficient controllers can improve the post-fault performance in six-phase induction machines supplied by parallel- connected converters if offline optimization is used to obtain a variable reference flux. Theoretical and experimental results confirm that the proposed flux adaptation method provides higher torque/power capability, lower degree of imbalance in the current sharing between windings and efficiency improvementMinisterio de Ciencia e Innovación ENE2014-52536-C2-1-R DPI2013- 44278-RJunta de Andalucía P11-TEP-755

Paisaje Antioqueño

En el número 2 del volumen 7 1988 presentamos a nuestros lectores esta sección de Artes Médicas, que hemos mantenido durante 11 años hasta ahora y esperamos mantener viva mientras nuestra revista. El artista encargado de inaugurar esta sección fue mi compañero, un amigo y colega inolvidable, el pediatra Gustavo Arango Jaillier. En ese momento nos regalaba un paisaje de Boyacá y ahora nos regala otro paisaje, esta vez nuestras queridas tierras Antioquia. Muestra un camino tortuoso, típico de Antioquia, donde literalmente hay que abrir el acceso al campo de fuerza entre las montañas y parece engullir-vengativo cuando al abrir, le duele la barriga. Es un camino solitario, silencioso como la muerte y recordándonos que es el camino que todos tenemos que recorrer ¡Este paisaje es como un presentimiento

Application of DSP in Power Conversion Systems — A Practical Approach for Multiphase Drives

Digital Signal Processing is not a recent research field, but has become a powerful technology to solve engineering problems in the last few decades due to the introduction by Texas Instruments in 1982 of the Digital Signal Processor. Fast digital signal processors have quickly become a cornerstone of high-performance electrical drives, where power electronic conversion systems have heavy online computation burdens and must be controlled using complex control algorithms. In this sense, multiphase drives represent a particularly interesting case of study, where the computational cost highly increases with each extra phase. This technology has been recognized in recent times as an attractive electrical drive due to its usefulness in traction, more-electric aircraft applications and wind power generation systems. However, the complexity of the required control algorithms and signal processing techniques notably increases in relation with conventional three-phase drives. This chapter makes a revision of the necessities of a high-performance multiphase drive from the digital signal processing perspective. One of the most powerful Texas Instruments’ digital signal processor (TMS320F28335) is used, and specific control algorithms, electronic circuits and acquisition processing methods are designed, implemented and analyzed to show its interest in the development of a high-performance multiphase drive

Multiphase Current Imbalance Localization Method Applied to Natural Fault- Tolerant Strategies

Multiphase machines are interesting options for high-reliability applications due to their inherent fault tolerance against open-circuit faults (OCFs). Moreover, if the regulation of the x-y currents is realized in open-loop mode using virtual voltage vectors (VVs), the mandatory post-fault control reconfiguration is avoided. The new reconfiguration-less approach was recently defined as a natural/passive fault-tolerant strategy, offering good prospects for industry applications. This work extends the idea to the fault detection (FD) procedure and suggests new settings for the current imbalance localization (CIL) method. The proposal is based on the vector space decomposition (VSD) approach that allows the joint detection of OCFs and stator resistances dissymmetry (RDs). Experimental results in a five-phase induction motor (IM) drive using VVs confirm the viability of the technique

Pleistocene environment and human occupations in the middle valley of the Magdalena river, Colombia.

Este artículo presenta una revisión de los trabajos disponibles sobre las ocupaciones humanas tempranas y las condiciones medioambientales en el Magdalena Medio. Nos enfocamos en la temporalidad de la transición del Pleistoceno al Holoceno con el fin de evaluar la potencialidad de la región para albergar sitios con evidencias del uso del paisaje por parte de sociedades de cazadores recolectores. Para lograr esto, caracterizamos la zona, elaboramos el contexto paleoambiental y relacionamos los sitios arqueológicos, con lo cual aportamos a la generación de hipótesis sobre la dispersión humana durante ese período.This article presents a review of the available work on early human occupations and environmental conditions in the middle valley of the Magdalena river. The focus is on the temporality of the transition from the Pleistocene to the Holocene epoch in order to assess the potential of the region to house sites with evidence of landscape use by collecting hunter societies. To achieve this, the area was characterized, the paleoenvironmental context was elaborated, and the archaeological sites were related, thereby contributing to the generation of hypotheses about human dispersion during the period

Bio-potential amplifier for potential gradient measurements

This work proposes a bio-potential amplifier suitable for measurements from an electric potential gradient sensor, in electro-encephalography (EEG). The sensor is an array made by three electrodes placed on the vertices of an equilateral triangle of reduced size. Measuring the gradient requires small separation between electrodes hence, very low amplitude signals, of a few μV, are obtained. Therefore, it is important to minimize amplifier noise and electromagnetic interference effects. In the proposed scheme, the first stage is a passive and balanced ac-coupling network adapted to the gradient configuration and the second stage is an 80 dB gain amplifier. The implementation requires a reduced number of components. Therefore, the circuit can be mounted just above the electrodes (active electrodes). The proposed amplifier was built and tested. It achieves a CMRR of 125dB at 50 Hz and an equivalent input noise voltage of 0,3μV RMS in the band 0.5 - 500 Hz. Finally, some preliminary results in the detection of occipital alpha rhythm are presented.Facultad de Ingenierí