Search results for "electronics"
showing 10 items of 4340 documents
Experimental study of the evolution of a bar breakage process in a commercial induction machine
2008
This paper analyzes the results of a destructive test developed on a commercial induction motor. The test is designed to reproduce in the laboratory the cage degradation process of an induction motor subjected to a high amount of working cycles, which include heavy startups. During each cycle, the main magnitudes related to the motor condition monitoring are registered, at steady state as well as at transient regime. From these magnitudes, some fault indicators described in the literature are calculated, and so, it is possible to follow their evolution. This analysis assesses the use of such small commercial machines in a test bed as a way of developing a failure that can be used to compare…
Non-linear digital control improving transient response: Design and test on a multiphase VRM
2010
Multiphase interleaved buck converters are widely used for point of load applications, especially for VRMs. Performance optimization issue often clashes with size and cost requirements thus leading the industrial and academic research to focus on advanced solutions. This paper presents a control technique for multiphase VRMs including two interacting sections: the linear loop implements a PWM peak current mode control and the nonlinear subsystem modifies few linear loop parameters under load transients only. Steady-state performances are affected by the linear control only while dynamic performance optimization is a non-linear algorithm issue. The proposed control system improves the dynami…
Analyses of Dual Polarization WDM and SCM Radio over Fiber and Radio over FSO for C-RAN Architecture
2016
En este trabajo se simulan y verifican experimentalmente los esquemas de transmisión para una Arquitectura de Red de Acceso Radio Centralizada (C-RAN) basados en la combinación de dos tecnologías: Radio sobre Fibra (RoF) y Radio sobre FSO (RoFSO). Las configuraciones propuestas se optimizan para la evolución a largo plazo (LTE) con un ancho de banda de 20 MHz utilizando una modulación de amplitud en cuadratura de 64-QAM en términos de magnitud de vector de error (EVM). En primer lugar, se comparan las mediciones de la multiplexación por división de polarización mediante la combinación de RoF y RoFSO (PDM-RoF/FSO) con los modelos de simulación. Esto se amplía con la combinación de PDM-Multip…
Measuring low H field and currents with AMR sensors
2017
The growing demand from the automotive industry for high accuracy magnetic sensors and the need to perform high resolution angular position measurements have been the drivers for the industrial research in magnetic sensing technologies. This paper describes the design and characterization of several experimental devices implementing simple magnetoresistive structures targeting contactless current measurement in the tens to hundreds of milliamps range with sub-mA resolution. The ultimate goal is to extend the application area of magnetoresistive sensors beyond their current niche in automotive into more general applications. The initial set of devices tested to-date has shown a sensitivity o…
A Non-Invasive Thermal Drift Compensation Technique Applied to a Spin-Valve Magnetoresistive Current Sensor
2011
A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensati…
New statistical post processing approach for precise fault and defect localization in TRI database acquired on complex VLSI
2013
International audience; Timing issue, missing or extra state transitions or unusual consumption can be detected and localized by Time Resolved Imaging (TRI) database analysis. Although, long test pattern can challenge this process. The number of photons to process rapidly increases and the acquisition time to have a good signal over noise ratio (SNR) can be prohibitive. As a result, the tracking of the defect emission signature inside a huge database can be quite complicated. In this paper, a method based on data mining techniques is suggested to help the TRI end user to have a good idea about where to start a deeper analysis of the integrated circuit, even with such complex databases.
Frequency mapping in dynamic light emission with wavelet transform
2013
International audience; Dynamic photon emission microscopy is an e cient tool to analyse today's integrated circuit. Nevertheless, the reduction of transistor's dimensions leads to more complex acquisitions where many spots can be seen. A frequency characterization of the whole acquired area can help to have a better understanding of it. With that purpose in mind, a new methodology to draw frequency mapping of dynamic light emission acquisition is reported. It is fully automated and based on wavelet transform and autocorrelation function. Regarding the possible use in an industrial context, the suggested method can help to localize abnormal emission activity and it gives some perspectives o…
A Multi-Position Calibration Method for Consumer-Grade Accelerometers, Gyroscopes, and Magnetometers to Field Conditions
2017
This paper presents a calibration method for consumer-grade accelerometers, gyroscopes, and magnetometers. Considering the calibration of consumer-grade sensors, it is essential that no specialized equipment is required to create reference signals. In addition, the less is required from the reference signals, the more suitable the method is on the field. In the proposed method, the novelty in the calibration of the gyroscopes lies in the exploitation of only the known net rotations between the positions in a multi-position calibration. For accelerometers and magnetometers, the innovation is that the direction of reference signals, the gravity and the magnetic field of the Earth, are estimat…
A two-end traveling wave fault location system for MV cables based on LoRa technology
2017
In this paper a new low cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of MV cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity and low cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly suited when commun…
Sub-mA current measurement by means of GMR sensors and state of the art lock-in amplifiers
2015
Electric current measurement at the range of μA in integrated circuit has been traditionally carried out by micro-electronically engineered systems, such as current mirrors or charging capacitors. However, off-line, i.e., non-intrusive methods provide advantages related to size and power consumption. In this sense, giant magnetoresistance (GMR) magnetic sensors are optimal due to their sensitivity and CMOS compatibility. In this work, we make use of specifically designed CMOS GMR-based current sensors in combination with a custom electronic interface based on a low-voltage low-power lock-in amplifier, demonstrating the capability of this combination for current measurement in the range of μ…