Fault signal propagation through the PMSM motor drive systems

This paper describes how a mechanical disturbance on the shaft of a variable speed permanent magnet motor (PMSM) is propagated to the supply input side of the drive system, and therefore may be detected by monitoring specific frequency components in the rectifier input current. The propagation of the disturbance from the torque disturbance, to the motor current, then to the dc link current and finally to the rectifier input current is derived as a series of transfer functions so that both the frequency and the amplitude of the disturbance component in the rectifier input current can be predicted for a specific mechanical disturbance. The limitations to detect the mechanical fault by monitoring only the supply currents are also addressed. Simulation and experimental results are presented to demonstrate the accuracy of the quantitative analysis, and the potential for fault detection using the rectifier input currents

Fault detection for PMSM motor drive systems by monitoring inverter input currents

This paper has proposed a fault detecting method for DC supplied permanent magnet synchronize motor (PMSM) drive systems by monitoring the drive DC input current. This method is based on the fault signal propagation from the torque disturbance on the motor shaft to the inverter input currents. The accuracy of this fault signal propagation is verified by the Matlab simulation and experiment tests with the emulated faulty conditions. The feasible of this approach is shown by the experimental test conducted by the Spectra test rig with the real gearbox fault. This detection scheme is also suitable for monitoring other drive components such as the power converter or the motor itself using only one set of current transducers mounted at the DC input side

Non-linear circuit based model of PMSM under inter-turn fault: a simple approach based on healthy machine data

The paper proposes a fast dynamic mathematical model to evaluate the performances of saturated permanent magnet synchronous machines (PMSM) under stator winding’s inter turn fault. The parameters of the model can be determined using only manufacturer’s data of the healthy machine. Two surface mounted PMSM have been considered to investigate the validity of the proposed approach; with distributed and concentrated winding. It has been shown that the proposed model predicts the fault current with a reasonable accuracy compared to the non-linear Finite Elements analyses and to the experimental results. This model can be incorporated in a global simulation environment of power electronic of electrical device since the computation time is very short

Análisis, diseño y dimensionamiento de las instalaciones eléctricas para una florícola

The following titling project focuses on the overall electrical design for a flower farm located in Machachi, Ecuador. The approach taken to develop the project will be the following. First, we identify the principal charges present in the farm to be able to estimate the approximate electrical demand. This helps us provide a complete design of a medium distribution network as well as a correct sizing of transformers, protections and a measuring system. Next, we will present a proposal of the structures and materials needed for the implementation of the project. Finally, we include the medium-voltage, electrical channeling, and the civil work blueprints...El siguiente trabajo de titulación se centra en el diseño eléctrico para una florícola localizada en el sector de Machachi en el Ecuador. Para desarrollar el proyecto, se identifican las principales cargas y en base a esto se estima la demanda eléctrica de la plantación. Esto permite realizar el diseño de la red de media tensión y dimensionar distintos elementos eléctricos tales como, transformadores, protecciones y sistema de medición. Se presenta además un detalle de las estructuras y materiales necesarios para la implementación del proyecto. Finalmente, se adjuntan los planos de media tensión, canalización eléctrica y obras civiles..

Hallazgos de la deformación miocárdica y cardioresonancia magnética en pacientes recuperados de COVID-19 con síntomas cardiacos de novo. Serie de casos.

We present a series of five cases of patients recovered from COVID-19, who requested specialized care for cardiac symptoms. Electrocardiogram, conventional echocardiography, myocardial deformation analysis, and finally cardiac magnetic resonance imaging were performed. The findings revealed a direct relationship between strain findings and late enhancement, suggesting a potential utility of myocardial strain techniques in the evaluation of post-COVID myocardial sequelae.Presentamos una serie de cinco casos de pacientes recuperados de COVID-19, que solicitaron atención especializada por síntomas cardíacos. Se realizaron electrocardiograma, ecocardiografía convencional, análisis de deformación miocárdica y finalmente resonancia magnética cardíaca. Los hallazgos revelaron una relación directa entre los hallazgos de strain y el realce tardío, lo que sugiere una potencial utilidad de las técnicas de deformación miocárdica en la evaluación de las secuelas miocárdicas post-COVID

Evaluation of saliency tracking as an alternative for health monitoring in PMSM-drives under nonstationary conditions

This paper evaluates the capability of saliency tracking to assess the health condition of permanent magnet synchronous motor (PMSM) drives operating under nonstationary conditions. The evaluated scheme is based on saliency tracking methods, which are associated to the accurate sensorless control of AC drives without zero speed limitations. In this work two representative saliency tracking architectures are evaluated: High Frequency (HF) injection, and PWM transient excitation. Although a monitoring approach based on HF injection was previously reported, a comparative study to evaluate the most representative saliency tracking schemes to assess health condition in drives was still missing. The aim of this work is to fill out this gap by evaluating and comparing two saliency-based monitoring schemes (one based on HF-injection and the other based on PWM transient excitation) to evaluate their performance in the presence of inter-turn winding faults. Simulation and experimental results are presented which confirm that both schemes offer excellent detection capabilities and that are suitable for drives operating under nonstationary conditions including standstill operation. Significant differences are also found for instance, PWM transient excitation offers improved accuracy since the approach is not affected by the inverter nonlinearities and is suitable for full-speed range applications. The main drawback here is complexity and the hardware requirements. Schemes based on HF-injection proved to be very simple and provide comparable results; however a good performance is only guaranteed for the zero-to-medium speed range applications which limit their applicability

Collateral, Liquidity and Debt Sustainability

We study Markov‐perfect optimal fiscal policy in an economy with financial frictions and sovereign default in the form endogenously determined haircuts on outstanding debt. Government bonds facilitate tax smoothing but also provide collateral and liquidity services that mitigate financial frictions. A debt Laffer curve exists, which induces the government to issue bonds to a point where marginal debt has negative welfare effects. Debt positions in the order of magnitude of annual output remain sustainable despite the option to default. When default happens, liquidity on the bond market is impaired, which can trigger extended periods of recurrent haircuts

Condition monitoring approach for permanent magnet synchronous motor drives based on the INFORM method

This paper proposes a monitoring scheme based on saliency tracking to assess the health condition of PMSM drives operating under non stationary conditions. The evaluated scheme is based on the INFORM methodology, which is associated to the accurate sensorless control of PM drives without zero speed limitation. The result is a monitoring scheme that is able to detect faults that would be very difficult to evaluate under nonstationary conditions. A relevant aspect of the proposed scheme is that it remains valid for full speed range, and can be used for standstill operation. Additionally, the approach is insensitive to the inverter nonlinearities which enhance the detection capabilities further respect to similar topologies. In this work the proposed approach is evaluated numerically and experimentally in the presence of incipient winding faults and inter-turn short circuits in a PM conventional drive. The obtained results show quick response and excellent detection capabilities not only in the detection of faults, but to determine their magnitude which is vital to avoid further degradation

Dinamička simulacija mehaničkih opterećenja – pristup zasnovan na svojstvima industrijskih elektromotornih pogona

Dynamic emulation of mechanical loads presents a modern and interesting approach for testing and validating performance of electrical drives without a real mechanical load included in the test rig. The paper presents an approach to dynamic emulation of mechanical loads when the load torque and inertia mass of emulated load can be significantly greater than that of laboratory test rig. Closed-loop control of load torque and feedforward compensation of inertia and friction torques are used in a test rig. The approach is focused on the use with standard industrial converters. The described method can be used for design and validation of speed control algorithms in mechatronic applications. Experimental results with the emulation of linear loads are presented in end of the paper.Dinamička simulacija mehaničkih opterećenja predstavlja moderan i zanimljiv pristup testiranju i validaciji ponašanja elektromotornih pogona bez uključenog stvarnog mehaničkog opterećenja u eksperimentalni postav. U radu je predstavljen pristup s dinamičkom simulacijom mehaničkih opterećenja za slučaj kada moment tereta ili moment tromosti simuliranog tereta mogu biti daleko veći od onih dostupnih u eksperimentalnom postavu. U postavu se koristi upravljanje momentom tereta u zatvorenoj petlji uz unaprijednu petlju kompenzacije momenta tromosti i momenata trenja. Pristup je usmjeren na upotrebu standardnih industrijskih pretvarača. Opisana metoda može se koristiti za sintezu i validaciju algoritama za upravljanje po brzini u mehatroničkim primjenama. U radu su predstavljeni eksperimentalni rezultati za slučaj simulacije linearnih tereta

Covid-19: fisiopatología, historia natural y diagnóstico

SARS CoV-2 is transmitted primarily through the airway. The mean time from exposure to presentation of symptoms is 5 days. Infected patients can remain asymptomatic or have a wide spectrum of manifestations such as: fever, dry cough, and general malaise. Approximately 20% of patients with COVID-19 require hospitalization (10% in the general area, 5% require intermediate care, and the remaining 5% enter intensive care due to their serious condition). Laboratory and radiological examinations show common but nonspecific abnormalities. Diagnosis is through the reverse transcription polymerase chain reaction test when it detects SARS CoV-2. This systematic review aimed to synthesize important elements related to the physiopathology, clinical manifestations, and diagnosis of COVID-19.SARS CoV-2 se transmite principalmente a través de la vía aérea. La media del tiempo desde la exposición hasta la presentación de la sintomatología es de 5 días. Los pacientes infectados pueden permanecer asintomáticos o tener un amplio espectro de manifestaciones como: fiebre, tos seca y malestar general. Aproximadamente, el 20% de pacientes con la COVID-19 requiere hospitalización (10% en área general, el 5% requiere cuidados intermedios y el 5% restante ingresa a cuidados intensivos debido a su estado de gravedad). Los exámenes de laboratorio y radiológicos muestran anomalías de común presentación, pero inespecíficas. El diagnóstico es a través de la prueba de reacción en cadena de polimerasa de transcripción inversa cuando detecta SARS CoV-2. El objetivo de la revisión que se presenta es sintetizar elementos importantes relacionados con la fisiolopatología, manifestaciones clínicas y diagnóstico de la COVID-19