Analysis of resolution in feedback signals for hardware-in-the-loop models of power converters

One of the main techniques for debugging power converters is hardware-in-the-loop (HIL), which is used for real-time emulation. Field programmable gate arrays (FPGA) are the most common design platforms due to their acceleration capability. In this case, the widths of the signals have to be carefully chosen to optimize the area and speed. For this purpose, fixed-point arithmetic is one of the best options because although the design time is high, it allows the personalization of the number of bits in every signal. The representation of state variables in power converters has been previously studied, however other signals, such as feedback signals, can also have a big influence because they transmit the value of one state variable to the rest, and vice versa. This paper presents an analysis of the number of bits in the feedback signals of a boost converter, but the conclusions can be extended to other power converters. The purpose of this work is to study how many bits are necessary in order to avoid the loss of information, but also without wasting bits. Errors of the state variables are obtained with di erent sizes of feedback signals. These show that the errors in each state variable have similar patterns. When the number of bits increases, the error decreases down to a certain number of bits, where an almost constant error appears. However, when the bits decrease, the error increases linearly. Furthermore, the results show that there is a direct relation between the number of bits in feedback signals and the inputs of the converter in the global error. Finally, a design criterion is given to choose the optimum width for each feedback signal, without wasting bit

LOCOFloat: A low-cost floating-point format for FPGAs.: Application to HIL simulators

One of the main decisions when making a digital design is which arithmetic is going to be used. The arithmetic determines the hardware resources needed and the latency of every operation. This is especially important in real-time applications like HIL (Hardware-in-the-loop), where a real-time simulation of a plant—power converter, mechanical system, or any other complex system—is accomplished. While a fixed-point gets optimal implementations, using considerably fewer resources and allowing smaller simulation steps, its use is very restricted to very specific applications, as its design effort is quite high. On the other side, IEEE-754 floating-point may have resolution problems in case of the 32-bit version, and excessive hardware usage in case of the 64-bit version. This paper presents LOCOFloat, a low-cost floating-point format designed for FPGA applications. Its key features are soft normalization of the results, using significand and exponent fields in two’s complement. This paper shows the implementation of addition, subtraction and multiplication of the proposed format. Both IEEE-754 versions and LOCOFloat are compared in this paper, implementing a HIL model of a buck converter. Although the application example is a HIL simulator, other applications could take benefit from the proposed format. Results show that LOCOFloat is as accurate as 64-bit floating-point, while reducing the use of DSPs blocks by 84%

Analysis of the aliasing effect caused in hardware-in-the-loop when reading PWM inputs of power converters

Hardware-in-the-loop (HIL) systems are commonly used to debug controllers in closed-loop operation. Therefore, the frequency response of the emulated subsystem is of special relevance. Undesirable oscillations can appear as a consequence of digitally sampling the switch control signals in power converter HIL models. These oscillations at relatively low frequencies, below the switching frequency, may confound the closed-loop operation and, therefore, the appropriate debugging of the controller. This paper shows that the lost information when an HIL model reads a PWM signal may create some output offset error or steady-state fluctuations, especially when the switching period and the sampling step get closer. The aliasing frequencies produced by the input sampling are calculated, and the small-signal analysis explains the relation between the output oscillation and the input PWM sub-harmonics. The output error spectrum proves that the main error sub-harmonics have the same aliasing frequency components. Both captured oscilloscope results obtained by an NI myRIO device and MATLAB simulations verify that significant distortions can be seen in the output inductor current if there is a low aliasing frequency in the digital version of the input PWM signal read by the HIL mode

Actualización diagnóstica y tratamiento de Celulitis Periorbitaria en el paciente pediátrico

Introduction: Periorbital cellulitis refers to the bacterial infection affecting the soft tissues around the eye. This infection is prevalent and potentially severe in children, possibly leading to complications such as abscesses and meningitis. This study aims to thoroughly examine existing scientific literature on periorbital cellulitis in young patients to better understand its clinical symptoms, primary causes, diagnostic techniques, treatment approaches, and potential associated complications. The methodology employed consisted of a literature search in specialized medical databases like Scielo, Pubmed, Scopus, and Google Scholar, using keywords like "periorbital cellulitis", "children", "diagnosis", and "treatment". The study included articles published within the last decade in both English and Spanish. Results indicated that children below 10 years old are more susceptible to periorbital cellulitis due to the spreading of upper respiratory infections. Symptoms consist of pain, redness, and swelling around the impacted eye, fever, and general malaise. Diagnosis primarily relies on clinical assessments and laboratory and imaging tests. Treatment typically involves antibiotics and occasionally surgical drainage of abscesses. Potential complications include vision impairment, intracranial abscesses, and meningitis. In conclusion, periorbital cellulitis is a potentially critical condition in pediatric patients that necessitates prompt diagnosis and treatment to prevent complications.Introducción: La infección bacteriana de los tejidos blandos que rodean el ojo se denomina celulitis periorbitaria. Entre los niños, es una infección frecuente y potencialmente grave que puede dar lugar a complicaciones como abscesos y meningitis. El propósito de este estudio es llevar a cabo una revisión exhaustiva de la literatura científica disponible. sobre la celulitis periorbitaria en pacientes pediátricos, con la finalidad de caracterizar sus manifestaciones clínicas, las etiologías predominantes, los métodos de diagnóstico, las estrategias terapéuticas, y las potenciales complicaciones asociadas. La metodología adoptada implicó realizar una exploración bibliográfica en bases de datos especializadas en medicina como Scielo, Pubmed, Scopus y Google Scholar, utilizando términos de búsqueda tales como "celulitis periorbitaria", "children", "diagnosis" y "treatment". Se incluyeron únicamente estudios reportados en los últimos diez años, tanto en inglés como en español. Resultados: Los niños menores de 10 años son más propensos a desarrollar celulitis periorbitaria, debida a la propagación de infecciones del tracto respiratorio superior. Los síntomas incluyen dolor, enrojecimiento e hinchazón alrededor del ojo afectado, fiebre y malestar general. El diagnóstico se realiza principalmente mediante examen clínico y pruebas de laboratorio e imagenología. El tratamiento incluye antibióticos, en algunos casos, drenaje quirúrgico de abscesos. Las complicaciones incluyen pérdida de visión, abscesos intracraneales y meningitis. Conclusiones: La celulitis periorbitaria es una afección potencialmente grave en pacientes pediátricos, que requiere un diagnóstico y tratamiento tempranos para evitar complicaciones

Evaluation of the different numerical formats for HIL models of power converters after the adoption of VHDL-2008 by xilinx

Hardware in the loop is a widely used technique in power electronics, allowing to test and debug in real time (RT) at a low cost. In this context, field-programmable gate arrays (FPGAs) play an important role due to the high-speed requirements of RT simulations, in which area optimization is also crucial. Both characteristics, area and speed, are affected by the numerical formats (NFs) and their rounding modes. Regarding FPGAs, Xilinx is one of the largest manufacturers in the world, offering Vivado as its main design suite, but it was not until the release of Vivado 2020.2 that support for the IEEE NF libraries of VHDL-2008 was included. This work presents an exhaustive evaluation of the performance of Vivado 2020.2 in terms of area and speed using the native IEEE libraries of VHDL-2008 regarding NF. Results show that even though fixed-point NFs optimize area and speed, if a user prefers the use of floating-point NFs, with this new release, it can be synthesized—which could not be done in previous versions of Vivado. Although support for the native IEEE libraries of VHDL-2008 was included in Vivado 2020.2, it still lacks some issues regarding NF conversion during synthesis while support for simulation is not yet includedThis research received no external fundin

Sub-harmonic oscillations attenuation in hardware-in-the-loop models using the Integration Oversampling Method

Hardware-in-the-loop (HIL) technology has become widespread for testing purposes, gaining special importance in micro-grids and renewable energy. One of the main challenges in HIL technology is its use in mid or high-frequency applications. In those cases, oversampling gate signals is a must to obtain enough accuracy and avoid undesirable sub-harmonic oscillations in the emulation that would not appear in a real scenario or offline electrical simulation. However, handling the extra information obtained through oversampling increases significantly the complexity of switched models since the oversampling methods deal with more than one sample per simulation step. It leads to extra design effort if the models are designed ad-hoc or increased hardware resources when using vendor tools that implement oversampling techniques. In both cases, oversampling traditionally implies an increase in the overall cost of the HIL system. This paper proposes the Integration Oversampling Method (IOM), which manages the extra information obtained through oversampling with a minimum impact on the models’ complexity. In fact, the power model is not changed at all and uses just one switch state per simulation step. The method consists in adding a small hardware block in the input of the gate signals. Using the additional information obtained through oversampling, it generates a set of switch states in every simulation step that minimizes the integrated error in the input reading. The experimental results obtained through an NI myRIO device show clearly enhanced performance when using IOM both in transient and steady-state operation. At the same time, the additional hardware resources necessary for IOM implementation are negligibl

Aplicación de células madre mesenquimales modificadas genéticamente para el tratamiento de la enfermedad de Sanfilippo tipo A.

El Síndrome de Sanfilippo en un tipo de mucopolisacaridosis caracterizada por la deficiencia enzimática. Concretamente, la sulfamidasa es la enzima implicada en el proceso patológico del Síndrome de Sanfilippo tipo A y es en este subtipo en el que se centra este trabajo de investigación. Los tratamientos existentes hasta la fecha no tienen la capacidad curativa, por lo que se establece el desarrollo de tratamientos alternativos más eficaces como una necesidad de urgencia sanitaria. En este estudio se propone el tratamiento con células madre mesenquimales transducidas con vectores virales adenoasociados para la sobreexpresión de la sulfamidasa. La estrategia está basada en varias aproximaciones. Por un lado, la propia capacidad inmunomoduladora de estas células madre unido a su tropismo dirigido a inflamación ayuda con este aspecto de la enfermedad. Además, proporcionan neuroprotección y promueven la regeneración neuronal en el sistema nervioso central. Por último, la expresión del transgén terapéutico ayuda a mejorar los niveles de glicosaminoglicanos acumulados como consecuencia de la enfermedad debido al proceso de corrección cruzada. Tales propiedades demuestran el gran potencial de la terapia propuesta, administrada de forma intranasal para actuar sobre tejido nervioso y/o forma intravenosa para actuar de manera sistémica. Dependiendo de la gravedad de la enfermedad, íntimamente relacionada con la edad del paciente, se procedería a administrar únicamente la forma intranasal (formas leves) o la combinación de ambas (formas más graves). Para los dos casos se requeriría de una administración múltiple cuya posología se determinaría en los diversos ensayos in vitro e in vivo propuestos en modelos de ratón y de perro, estudiando la biodistribución, eficacia, dosis y toxicología de la terapia. Finalmente, se proponen dos ensayos clínicos, distinguiendo cada uno de ellos por la edad de los pacientes (1 a 6 años; 7 a 15 años), resultando en una novedad con respecto al resto de ensayos clínicos realizados sobre el síndrome de Sanfilippo al incluir a pacientes de edades más avanzadas.pre-print3069 K

Acute Effects of Muscular Fatigue on Vertical Jump Performance in Acrobatic Gymnasts, Evaluated by Instrumented Insoles: A Pilot Study

The study of fatigue during training is becoming a very useful tool to avoid possible injuries not only during the training sessions but also during recovery time. Many researches have proved that concepts such as muscular fatigue and postactivation potentiation have a close relationship. With this aim, vertical jump can provide a very important information that can help to analyze the muscular fatigue that happened during this type of activity, mainly if the monitoring system is able to measure jumping parameters during their regular training session in their natural training environment. This study was performed with instrumented insoles called ECnsole. These insoles were tested with a group of twelve volunteers. In a tumbling surface, the participants performed a jumping protocol in three conditions: rest, fatigue-induced, and recovery. Using these validated insoles, the acrobatic gymnasts showed an inability to use the stretch-shortening cycle for improving vertical jumping performance after fatigue condition, although no deterioration of jump performance was found.Junta de Andalucía European Commission P10-TIC5997European Commissio

Creación de recursos multimedia de autoaprendizaje para la docencia práctica de Genética. Valoración de su eficacia en la adquisición de habilidades y competencias

Memoria ID-0225. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2016-2017