Detection of inter-turn faults in multi-phase ferrite-PM assisted synchronous reluctance machine

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currentsPeer ReviewedPostprint (published version

Effects of scientific information format on the comprehension self-monitofing processes: question generation

Generating questions is a regulatory action associated with self-monitoring processes in comprehension tasks: subjects can ask information seeking questions to solve comprehension obstacles. A sequence of two related experiments were conducted to trigger, classify and analyse questions asked under different conditions: reading a text about experimental scientific devices operating, watching these devices in a DVD and manipulating them in the LAB. Students' information seeking questions were classified using a simple taxonomy. Taking into account the multimedia learning principles, the advantages of realistic animations for understanding time-depending processes and the effect of the procedural-motor activity, were expected students would ask different questions under each of the aforementioned conditions. Results confirmed the expectations: the reading condition triggered more questions addressed to describe the entities while the watching and manipulation conditions stimulated more causal questions. In addition, the effect of prior knowledge on questions including scientific concepts was analyzed

Analysis and implementation of a methodology for optimal PMa-SynRM design taking into account performances and reliability

Automotive applications focus to develop drive-train technologies with higher energy efficiency and lower environmental impact. Electric and hybrid vehicles are gaining popularity since they fulfill these requirements . The aim of optimal motor design is to achieve high torque and power densities, wider speed range and high efficiency within the area defining the most frequent operating points. This work presents a methodology to optimize electric motors for traction applications considering a multi-physics approach. The magnetic behavior is evaluated using a complex reluctance networks capable to compute the cross-coupling. The results of the magnetic model are the inductances, iron losses, and magnet flux linkage. The thermal behavior is evaluated using a thermal network and it is coupled with the magnetic model. The electric model is feed with the solution of the thermal and magnetic model. The electric model aims to calculate the whole operating area of the motor to allow optimizing the machine considering the most frequent operating zone. Therefore, a fast tool to evaluate different variables within the torque-speed map is convenient for this purpose. In this context, starting from a preliminary motor design, and taking into account motor cross-coupling effects and power losses, this thesis presents a new methodology for optimizing and evaluating the behavior of permanent magnet machines, such as synchronous reluctance machines, and permanent magnet assisted synchronous reluctance machines, in all operational points. Apart from the torque and efficiency, many other electrical variables can be obtained, such as the current space vector angle, power factor or electrical power among others. The proposed methodology also allows optimizing the design of the machine under a pre­established control law; thus obtaining the current set point trajectory in the dq frame and allowing a fast and accurate evaluation of motor performance.The results obtained by means of the proposed simulation tool are compared against finite element analysis simulations and experimental data, thus validating the usefulness and accuracy of the proposed methodology.El sector de la automoción se está centrando en las tecnologías con alta eficiencia y un bajo impacto medioambiental. En este sentido el desarrollo de vehiculos eléctricos o hibridos está ganando importancia en este sector. Por lo tanto, el diseño de motores eléctricos que cumplan las especificaciones necesarias para aplicaciones de tracción eléctrica es un punto de especial interés . El principal objetivo en la optimización de motores eléctricos es conseguir altas densidades de par o potencia, alta eficiencia y un buen factor de potencia, teniendo en cuenta la zona de trabajo más común. Este trabajo presenta una metodologia para optimización de motores eléctricos, concretamente motores de reluctancia síncrona, para aplicaciones de tracción eléctrica. Para ello es necesario crear diferentes modelos para evaluar el comportamiento eléctrico, térmico y magnético del motor así como calcular los diferentes puntos de trabajo. El modelo magnético, que está basado en redes de reluctancia, permite calcular las inductancias, el flujo magnético del imán y las pérdidas en el hierro teniendo en cuenta la saturación cruzada. El modelo térmico estará basado en redes térmicas y permite evaluar la temperatura de diferentes partes del motor (dientes, bobinado, cabezas de bobina o imanes) para evaluar la viabilidad de estos motores y definir bien el valor de algunos parámetros como la resistencia del bobinado y las propiedades magnéticas del imán. El modelo eléctrico está basado en la resolución de las ecuaciones completas del motor en los ejes dq, los parámetros necesarios (inductancias, resistencia, perdidas en el hierro, flujo del imán) serán obtenidos en los modelos magnético y térmico. En este punto, la metodología propuesta es capaz de calcular todos los puntos de operación de la máquina. Hay que remarcar que en este punto se puede calcular la eficiencia, factor de potencia, ángulo de corriente. La tesis propuesta empezará el proceso diseño optimizado del motor calculando un pre-diseño para introducirlo en un optimizador que usará los mapas calculados para evaluar su función de coste teniendo en cuenta que estos mapas estarán obtenidos considerando saturación cruzada, perdidas en el hierro y variaciones de temperatura, se puede afirmar que el motor resultante está evaluado en todos sus dominios exceptuando el mecánico. Para el análisis mecánico se propone un estudio en elementos finitos posterior a la optimización. En este análisis se podrán introducir estructuras que mejoren la resistencia mecánica del motor y que serán restricciones para una nueva optimización. Una vez cerrado el proceso iterativo entre optimización y análisis mecánico se tendria el motor final. En la tesis propuesta se usa esta metodologia para diseñar varios motores, con lo cual se permite la validación de la misma.Postprint (published version

Absolute dimensions of the G7+K7 eclipsing binary star IM Virginis: Discrepancies with stellar evolution models

We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations we derive accurate absolute masses and radii of M(1) = 0.981 +/- 0.012 M(Sun), M(2) = 0.6644 +/- 0.0048 M(Sun), R(1) = 1.061 +/- 0.016 R(Sun), and R(2) = 0.681 +/- 0.013 R(Sun) for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 +/- 100 K and 4250 +/- 130 K. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100 K and 150 K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly-rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4 Gyr for the system, and a metallicity [Fe/H] of approximately -0.3 that is consistent with other indications, but requires confirmation.Comment: 14 pages, 13 figures. Accepted for publication in Ap

Reliable Design of PMaSynRM

Electric vehicles require highly reliable and resilient electric motors, due to the harsh operating conditions they must withstand. To this end, there is a current trend to design rare-earth-free machines. Traction electric motors must be optimized in terms of efficiency, torque density, power factor, constant power speed ratio, and cost. Although different technologies are available, permanent magnet assisted synchronous reluctance motors (PMa-SynRM) are promising candidates for such applications. Nowadays, the optimal design process of electrical motors is based on finite element method (FEM) simulations. However, it is very time consuming with a heavy computational burden process, so in order to speed up the optimization process, it is very appealing to have an accurate pre-design of the machine. In this chapter, the electromagnetic pre-design of a PMaSynRM is developed. In the proposed electromagnetic pre-design process, the geometry of the machine is calculated based on analytical equations that take into account the thermal, electrical, magnetic, and mechanical behavior of the machine to ensure a suitable and reliable design

Una experiencia de evaluación continuada en Radiación y Propagación

Postprint (author’s final draft

Estudio de la cristalización de ZrO2 en el sistema sol-gel: ZrO2-SiO2

Los polvos en el sistema ZrO2-SiO2, obtenidos por el método sol-gel, se produjeron utilizando alcóxido de silicio (TEOS) y propóxido de zirconio. Después de la gelación, se investigó la cristalización del ZrO2 por difracción de rayos X (DRX), análisis térmico (ATD/ATG), y microscopía electrónica de barrido (MEB). Los geles frescos eran amorfos. Se llevaron a cabo tratamientos térmicos de 100 hasta 1400°C, manteniéndolos por períodos de tiempo de hasta182h. La primera fase en cristalizar fue la zirconia tetragonal Z(t), entre 300 y 500°C. La temperatura de cristalización para las composiciones ricas en zirconia fue menor y aumentó a medida que el contenido de sílice aumentaba. El análisis térmico diferencial (ATD) mostró que la cristalización de Z(t) ocurría en dos pasos. La transformación de zirconia tetragonal a monoclínica ocurría a 1000°C y era claramente observada sólo en composiciones ricas en zirconia (>80%). La sílice permanecía amorfa hasta 1200°C, cuando se formaba la fase ZrSiO4. Se propuso un diagrama de fases sol-gel metaestable para mostrar el proceso de cristalización en el intervalo de temperatura de 100 a 1400°C

Gamification in Ecology-Oriented Mobile Applications-Typologies and Purposes

Mobile applications viewed as digital social change tools are focused on sustainable development, particularly in topics that address ecology and the environment. In this research, the aim is to systematize a review of the 10 most downloaded mobile applications in this context, but deepening on those that use game elements in their interface, organizing them according to components, mechanics and playful dynamics. Findings demonstrate the role of levels and achievements as more repeated dynamics, and challenges and feedback as more relevant elements in gameplay, and finally, emotions and narratives as components of the gamified experience. The incorporation of these elements in mobile games shows that digital gamification in the environmental context is organized from an alternative perspective, where argumentation, the succession of events, the progressive incorporation of difficulty and the interaction with the computerized system modify the traditional view that sees gamification as a superficial system of points