Ejercicios semanales

Ejemplos de ejercicios semanales cortos en los que el tiempo de resolución está limitado a un máximo de 10 minutos. Se evalúan conceptos aprendidos en la semana anterior y las preguntas son muy directas. En algunos de ellos no se pide hacer ningún cálculo y, en el resto, los cálculos son sencillos. Es importante que intentéis resolverlos sensiblemente por debajo del tiempo recomendado para probar vuestros conocimientos y destreza. Cualquier duda que surja con ellos deberíais resolverla en la misma semana en la que se ha dado esa parte de la materia.


Conceptos básicos, Ley de Ohm, asociación de resistencias.

Leyes de Kirchhoff, equivalencia de fuentes.

Ecuaciones de nodo

Ecuaciones de malla

Teorema de Thévenin


Dominio de la frecuencia. Nodos y mallas

Teorema de Thévenin

Bobinas acopladas

Teorema de superposición

Potencia en alterna

Conductive 3D Printed PLA Composites: on the interplay of mechanical, electrical and thermal behaviours

I. Tirado-Garcia, D. Garcia-Gonzalez, S. Garzon-Hernandez, A. Rusinek, G. Robles, J.M. Martinez-Tarifa, A. Arias, Conductive 3D Printed PLA Composites: on the interplay of mechanical, electrical and thermal behaviours, Composite Structures, Volume 265, 2021, 113744, ISSN 0263-8223, https://doi.org/10.1016/j.compstruct.2021.113744.

Abstract – Additive manufacturing (AM) techniques represent a real challenge to manufacture novel composites with coupled multifunctional properties. This work focuses on the mechanical, electrical and thermal behaviours of 3D printed polymeric composites of polylactic acid (PLA) filled with carbon black (CB) conductive particles. The incorporation of conductive particles within the polymer matrix allows for programmable conduction paths via the printing process, whose electric properties are intimately coupled to thermo-mechanical processes. In this study, samples were prepared using a fused deposition modelling (FDM) printer, controlling the filament orientation to manufacture three different types: longitudinal (0°); transverse (90°); oblique (±45°) printing orientations. Different types of multifunctional characterisation have been made: (i) electro-thermal tests, evaluating the influence of electrical conductivity on the sample temperature due to Joule’s heating; (ii) thermo-electrical tests, analysing the influence of temperature on the DC resistance of the samples (iii) mechano-electrical tests, analysing the effect of mechanical deformation on the specimens’ electric resistance. The results show a strong dependence of printing direction on the material properties of 3D printed conductive-PLA and identify strong thermo-electro-mechanical interplays. The results of this work will contribute to the AM progress in functional electro-mechanical components with potential applications in biosensing devices, composite sensors, 3D electrodes and soft robotic industry.

Keywords – Additive manufacturing (AM); Conductive Polymer Composites (CPC’s); Fused deposition modelling (FDM); carbon black (CB); polylactic acid (PLA); Multifunctional materials

Towards Series Arc Fault Detection in More Electrical Aircrafts

M. G. d. l. Calle, G. B. d. María, D. Izquierdo, R. Martín, J. M. Martínez-Tarifa and G. Robles, “Towards Series Arc Fault Detection in More Electrical Aircrafts,” 2020 IEEE 3rd International Conference on Dielectrics (ICD), Valencia, Spain, 2020, pp. 866-869, doi: 10.1109/ICD46958.2020.9342025.

Abstract – The trigger of an electric arc represents an unacceptable risk to the safety of the aircraft and a blocking point to certify the new high-voltage architectures. These high-voltage networks are required to cover the growing electric energy demand for new developments. Thus, the study of the electric arc phenomenon, its detection and the parameters affecting its behavior is needed to progress along the path to the all-electric aircraft.

Partial discharges measurement during under-damped steep-fronted overvoltages

J. M. Martínez-Tarifa and G. Robles, “Partial discharges measurement during under-damped steep-fronted overvoltages,” 2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), Dubrovnik, Croatia, 2020, pp. 1-5, doi: 10.1109/I2MTC43012.2020.9129294.

Abstract – Inverter-fed drives have become essential in most industrial processes nowadays to control the speed of rotation of electric motors. Unfortunately, the insulation of these electric motors show unexpected failures due to the appearance of partial discharges (PD). These type of discharges undermine the insulation along time creating weak spots than can cause total breakdowns. Thus, the detection of partial discharges is a challenge that must be faced by electric motor manufacturers and users. The problem of detection is intensified because the voltage supplied to the motors is based on steep-fronted pulses and PD are also very narrow pulses so it is quite complex to separate them from the electrical interferences created by the train of square pulses. In this paper, two different radio- frequency (RF) sensors will be used to detect PD in an insulation system subjected to square voltages with low rise-times. The response will be analyzed in the UHF range to select the best option for the detection of those hazardous under-damped pulses.

Piezoelectric Energy Harvesting System to Detect Winding Deformation in Power Transformers

Robles G., Febbo M., Machado S.P., García B. (2020) Piezoelectric Energy Harvesting System to Detect Winding Deformation in Power Transformers. In: Ball A., Gelman L., Rao B. (eds) Advances in Asset Management and Condition Monitoring. Smart Innovation, Systems and Technologies, vol 166. Springer, Cham.


Open Access available at https://link.springer.com/content/pdf/10.1007%2F978-3-030-57745-2.pdf

Abstract – One common use of energy harvesting systems is the installation on applications where the access to conventional sources of energy is difficult due to availability, space constraints, environmental hazards or sealed equipment. In this work, we propose an alternative use of an energy harvesting system based on a piezoelectric that takes the vibration of a transformer tank due to winding deformations and hence helps to monitor the condition of the equipment. The system consists on a cantilever piezoelectric beam with a mass tuned to the resonant frequency of the vibration. The output of the piezoelectric is connected to a quadrupler, a low-drop regulator and a capacitive storage. The harvested voltage is planned to supply a low power microprocessor that detects changes in the vibration measurements to determine an abnormal behavior of the transformer. This work introduces the causes of abnormal vibration of transformers, describes the installation of the piezoelectric on a model that generates the same acceleration as the vibration of a transformer tank and studies the capability of charging capacitors to determine the feasibility of the method.

Keywords – Condition monitoring, Energy harvesting, Piezoelectrics, Power transformers, Vibration analysis

Identification and Location of Partial Discharge Defects in Medium Voltage AC Cables

Muhammad Shafiq, Guillermo Robles, Amjad Hussain, Kimmo Kauhaniemi, Matti Lehtonen, Identification and Location of Partial Discharge Defects in Medium Voltage AC Cables. 5 August 2019. Proceedings of the 26th Nordic Insulation Symposium NORD-IS, Trondheim (Norway), pp 22-27. ISSN 2535-3969.

Open access available athttps://doi.org/10.5324/nordis.v0i26.3269

Abstract – The presence of partial discharge (PD) in electrical equipment is the confirmation or indication of an ongoing degradation of its dielectric insulation. PD study is a widely used tool for condition monitoring of medium voltage (MV) cables. The location of the defects can be considered as one of the most important tasks of diagnosis in underground installations of MV cables. A lot of references can be found on the location of single PD sources along the cable. However, several PD defects can be active simultaneously along a cable section. This paper presents an experimental study on a MV cable having two PD sources and noise. Adopting one end measurement technique, a high frequency current transformer (HFCT) is used to capture the PD current pulses. A simple approach of identification of the PD signals originated from different PD sources is presented based on wave-shape study along with a time domain reflectometry analysis. The presented measurement methodology and time domain analysis technique provides a convenient way for detection and location of more than one PD sources along a cable section.

Uncertainty Sources in the Estimation of the Partial Discharge Inception Voltage in Turn-to-Turn Insulation Systems

M. G. De La Calle, J. M. Martínez-Tarifa, Á. M. Gómez Solanilla and G. Robles, “Uncertainty Sources in the Estimation of the Partial Discharge Inception Voltage in Turn-to-Turn Insulation Systems,” in IEEE Access, vol. 8, pp. 157510-157519, 24 August 2020.
Electronic ISSN: 2169-3536

doi: 10.1109/ACCESS.2020.3018870


Abstract — Partial discharges (PD) are one of the main causes of premature failure in low-voltage motors driven by variable-speed drives. The use of these control systems are being quite extended due to new applications, such as the more electric aircraft (MEA) or hybrid and electric vehicles, and this has pushed research towards appropriate designs of electric motors to avoid, as much as possible, the presence of PD within their windings. This article presents a model to predict the partial discharge inception voltage (PDIV) in the insulation of low-voltage machines. A value for the secondary ionization coefficient based on a statistical study is also proposed. The deviations of the model are also studied by obtaining the uncertainty of the value of that coeficient and the predicted values of the PDIV for a set of wires. This uncertainty will be compared with other error sources such as generator harmonics and humidity. Finally, the tests are done for different temperatures extend the model applicability.

Keywords — Insulation design, inverter-fed machine, partial discharges, Paschen’s law, temperature, Townsend’s coefficients.

Concurso para encontrar el 7º ponente de TEDxUC3M (finalizado)

La información contenida en este post está obtenida del siguiente enlace al formulario del concurso:



TED es una organización sin ánimo de lucro estadounidense fundada en 1984 que comparte con la audiencia ideas relacionadas con la educación, el emprendimiento y la tecnología (TED), valores que estructuran nuestro futuro. Asimismo, TEDx es el formato organizado de forma independiente con el objetivo de compartir ideas de forma local. Es este al grupo que pertenece nuestro evento, TEDx University Events.


TEDxUC3M es una asociación de la Universidad Carlos III de Madrid fundada para la organización de un evento TEDx en el mes de abril de 2020 y futuros años. La forman varios estudiantes de los distintos campus de la universidad que tienen como objetivo común el dar voz a ideas locales que puedan marcar una diferencia en la audiencia y personas que vean las charlas.

– En los días comprendidos entre el 3 y el 17 de febrero estará abierto el plazo para rellenar el formulario.
– Tendréis que grabar y adjuntar al formulario un vídeo de MÁXIMA DURACIÓN 1 MINUTO desarrollando el tema de vuestra charla de forma resumida, relacionado con la temática del evento, ROMPIENDO PARADIGMAS.
– Los vídeos serán analizados por los miembros de TEDxUC3M y seleccionarán a los cinco mejores.

El ganador será el séptimo ponente del evento “TEDxUC3M 2020: Rompiendo Paradigmas” que tendrá lugar en el Aula Magna del campus de Getafe de la Universidad Carlos III de Madrid en el mes de abril.

Más información en shorturl.at/ouyJ6


Piezoelectric energy harvesting

One common use of energy harvesting systems is in those places where the access to conventional sources of energy is difficult due to availability, space constraints, environmental hazards or sealed equipment. This article explores the possibilities of piezoelectrics to extract electrical energy and store it in capacitors to supply power of ultra-low power microprocessors.

The piezoelectric under test is a Lead Zirconate Titanate PZT-5J with reference S128-H5FR-1808YB manufactured by MIDE. The tests I am going to conduct are aimed at a specific application in which the piezo has to extract energy at 100 Hz with an acceleration as low as 2 ms^{-2} or 0.2 g.

From right to left, the setup consists of a signal generator, signal conditioner and amplifier (top), signal amplifier (bottom), oscilloscope and vibrator or shaker with the piezoelectric (behind the oscilloscope).

Continue reading Piezoelectric energy harvesting

Conex Plus – Primera convocatoria de solicitudes

Formo parte de los supervisores del programa CONEX-Plus:

La Universidad Carlos III de Madrid (UC3M) pone en marcha un programa de financiación para movilidad entrante, denominado CONEX-Plus. Este programa tiene por objeto impulsar la formación y el desarrollo profesional de investigadores internacionales experimentadas, sobre la base de la denominada dimensión triple “i” (Aspectos Internacionales, exposición Intersectorial e Interdisciplinariedad). Todos los participantes se beneficiarán de un programa de formación con módulos dedicados a habilidades transversales relevantes y formación en la industria.

Las áreas estratégicas de investigación se identifican en la “Estrategias Nacionales y Regionales para la Especialización Inteligente” (RIS3) de la Comunidad de Madrid:

  • Materiales Avanzados, Tecnologías de Fabricación y Espacio.
  • Energía, medio ambiente y transporte (incluida Aeronáutica).
  • Salud y Biotecnología.
  • Tecnologías de la Información y Comunicaciones.
  • Ciencias Sociales y Humanidades.

Dentro de estas áreas, los temas que puedo dirigir serían los marcados en negrita:

  • Área Nanotecnología, Materiales Avanzados, Tecnologías Industriales y del Espacio
    • Nanociencias
    • Materiales avanzados
    • Tecnología y Conservación del patrimonio
    • Desarrollo de instrumentación, microsistemas y sensores
    • Tecnologías industriales (incluye procesos de menor impacto ambiental) y robótica aplicada
    • Tecnologías de acceso al espacio y demostración en órbita para pequeñas cargas de pago
    • Técnicas, equipamiento, instrumentación avanzada, sistemas a bordo y sistemas terrenos de seguimiento y monitorización de satélites
    • Desarrollo de aplicaciones basadas en información de satélites
    • Investigación científica del espacio exterior
    • Fotónica
  • Área Energía, Medio Ambiente y Transporte (incluida Aeronáutica)
    • Tecnologías de uso sostenible, restauración del medio natural y conservación de la biodiversidad
    • Gestión de residuos, vertidos y emisiones: incluye microcontaminantes, contaminantes emergentes, reutilización/eliminación de materias residuales, recuperación de energía
    • Fuentes de energía renovables y sostenibles
    • Redes eléctricas inteligentes
    • Sistemas de navegación, control de tráfico y seguridad en el transporte
    • Diseño, desarrollo y fabricación de sistemas de propulsión y sistemas auxiliares de vehículos de transporte

Los adjudicatarios llevarán a cabo un proyecto de tres años, libremente elegido, en uno de los 27 departamentos de la UC3M, con el apoyo de un supervisor de la UC3M.

El rendimiento del proyecto debe estar respaldado por la realización de una estancia en una organización no académica de alto nivel, que permita el máximo beneficio de esta Ayuda de Investigación en el desarrollo de su carrera.

Toda la información se puede encontrar en:


O contactando conmigo:


Fecha límite de entrega de solicitudes: 30 de septiembre de 2019.