Francisco Javier Rodriguez Sanchez

Optimum conditioning of PbSe photoconductive detectors in measurements without chopping

This paper analyses the most important sources of uncertainty in the circuitry of an infrared radiation measurement system without chopping based on PbSe photoconductive detectors. It studies the influence of the conditioning system on noise and thermal drift, proposing two optimum diagrams depending on the effect to be minimised. Finally, a study of the noise and drift in a complete circuit is carried out, demonstrating the effects generated by the circuitry which may limit the final precision of the system. The overall results obtained demonstrate that with a suitable design the undesired effects of the conditioning circuitry can be kept at acceptable levels for a good number of applications.

Calculation and optimisation of the maximum uncertainty in infrared temperature measurements taken in conditions of high uncertainty in the emissivity and environment radiation values

This paper develops a method that enables the most suitable range of wavelengths to be ascertained in which to take infrared temperature measurements of surfaces in the open air in conditions in which high uncertainty exists in the environmental radiation and emissivity values. The optimisation criterion adopted for the error is that of achieving the narrowest possible band of maximum uncertainty. The results demonstrate that it is possible to cancel out the solar radiation contribution to the maximum uncertainty present in the measurement whilst still working in short wavelengths where this radiation is very intense and, therefore, optimise the band of uncertainty produced by emissivity and environment radiation.

Infrared temperature measurement system using photoconductive PbSe sensors without radiation chopping

This paper proposes an infrared temperature measurement system based on a PbSe photoconductive sensor that enables a high quality measurement to be obtained without chopping the radiation. The main problems that arise from eliminating chopping are analysed and the solutions adopted in order to reduce their effect are described. The quality of the measurement obtained using the system is quantified for a real application and is compared with other contributions that are independent of whether radiation chopping is performed or not.

Hinf current controller for input admittance shaping of VSC-based grid applications

This paper presents a current controller that shapes, in the frequency domain, the input admittance of voltage-source converters connected to the grid. The controller is obtained by means of a

Vigilance system in rails for train hot point temperatures during circulation

\mathcal {H}_\infty

Resonance damping of LCL filters via input admittance frequency shaping

synthesis procedure, which minimizes the difference between the application closed-loop input admittance and a model-reference defined by the designer. This formulation achieves good accuracy in both modulus and phase. The proposed methodology allows the fulfilment of other current control objectives, such as current tracking, by defining frequency regions where each objective is desired. Experimental results show the good response of the proposed controller, both in frequency and time domain.

H ∞ simultaneous admittance and tracking current controller of three-phase active grid front-ends

Wheels, hubs and brake discs in a train during its circulation are under mechanical strains that make its temperature increase above the environment temperature. Mechanical defects in those elements produce an excessive friction and, as a consequence of it, an important increment of its temperature in relation to normal values. Detecting these anomalies is essential to avoid accidents and it is performed by fixed systems located next to rails which make infrared temperature measurements of hot points and send them to a supervisory station that takes the proper steps. The paper introduces the most important problems which must be dealt with during the designing stage of the measurement system. It also explains the solutions taken by the authors in order to assure the minimum operative aims demanded by the application. These problems includes: the choice of the detector and measurement method, communication with the supervisory station, and the environment conditions. Finally, the research lines followed by the authors in order to improve and extend the systems capabilities are explained.

Main limitations in infrared temperature measurement of train hot points

This paper presents a novel active damping technique of current-controlled grid-connected power converters through LCL filters. Based on ℋ∞ synthesis algorithms, a grid current controller is obtained so that the grid-connected power converted-based application admittance resembles a given frequency reference. By defining a low resistive admittance as the reference, considered application resonance is effectively damped, reducing grid current oscillations under grid voltage variations and avoiding their associated stability problems. Presented grid current controller senses only the PCC grid voltage and current, and is experimentally tested in both time and frequency domains. Additionally, the effectiveness of presented damping method is proved under different grid impedance scenarios.

Chapter 7 – Cooperative Systems

This paper proposes an H∞ current controller that allows power converter input admittance shaping, both in modulus and in phase, in a three phase voltage source converter to grid connection through an L filter. In addition to this new feature, controller allows grid current tracking. Proposed controller tries to solve then trade-off problem between stand-alone converter performance (current tracking) and its influence on global stability (admittance control) by an intuitive controller design. Time and frequency domain simulated results demonstrate the good performance of the proposed method.

Project based learning experiences for embedded systems design

Nowadays, in order to guarantee the security in passenger and goods railway transport, fixed systems located in rails are used to measure axles, wheels and brake discs temperatures during train circulation so that abnormally high temperatures as a result of a malfunction can be detected. Measurement systems in this kind of application may be affected by different uncertainty sources, characteristic of infrared temperature measurements, which limit the accuracy of the estimated measurement. Uncertainty sources are specially important in these applications due to:Nowadays, in order to guarantee the security in passenger and goods railway transport, fixed systems located in rails are used to measure axles, wheels and brake discs temperatures during train circulation so that abnormally high temperatures as a result of a malfunction can be detected. Measurement systems in this kind of application may be affected by different uncertainty sources, characteristic of infrared temperature measurements, which limit the accuracy of the estimated measurement. Uncertainty sources are specially important in these applications due to: (1) Extremely variable emissivity as a result of stain or different paints used on the surfaces. (2) Difficult evaluation of the environments radiation as measurements are made outdoors. (3) Alarm temperatures are only about 40 degrees Celsius to 80 degrees Celsius above the environment temperature. The paper analyses the effects of these uncertainties. The results show that, in order to get the minimum uncertainty peaks in the estimated temperature, the proper duty waveband is 3 - 5 micrometer. They also show that, with a proper choice of the wavelength, the uncertainty due to solar radiation remains masked by the uncertainty due to the lens emissivity.