Alfonso Garcia

Torque Control of Switched Reluctance Motors

This paper presents the performance of an instantaneous torque control method. The simulation and experimental results illustrate the capability of Switched Reluctance Motors (SRM) being used in the motor drive industry. Based on experimental data, the advantages of this control method and its disadvantages in practical implementation were studied. The model used in the simulation is the linear magnetic model which has the 12/8 structure, the same structure as the experimental switched reluctance motor.

Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review.

Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a “simple” and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc.

Magnetic sensor for building structural vibrations.

This paper shows a new displacement-to-frequency transducer based on the variation of a coil inductance when a magnetic core is partially or completely inserted inside. This transducer is based on a Colpitts oscillator due its low manufacturing price, behavior and immunity to noise. A tank circuit with a configuration in parallel was used because it can be employed at lower frequencies and it enables it to make a direct analysis. The sensor has a dynamic range equal to the length of the coil. The cores can exchange sensors (coils with its ferromagnetic core) using the same electronic measuring system. In this way, with only an electronic circuit, the core sensor determines the measurement range. The obtained resolution is higher than 1/100,000, and the sensor also allows the measurement and knowing in real time the effect of vibration, thermal expansion, referred overload movements, etc.., that can occur in the structural elements of a building.

Biaxial magnetometer sensor

A simple two-axis fluxgate magnetometer has been developed to measure weak magnetic fields by using magnetization rotation processes. To obtain these magnetization processes, we use circular discs of a very thin soft magnetic material as cores. These cores are magnetized by a rotating magnetic field high enough to saturate them. Thus, the magnetization processes are due to magnetization rotation and the only losses are due to macro-eddy currents. This kind of device can also be used to measure the magnetic field in two perpendicular directions by using a single core and, in principle, the exciting field frequency can be greater than in conventional fluxgate magnetometers. The maximum calculated sensitivity of this device is 5.3 times higher than that of a conventional fluxgate magnetometer of similar dimensions.

A method for calculating the magnetic field produced by a coil of any shape

This work deals with the design of coils to obtain a desired magnetic field in the axial direction. A computer program has been developed to implement the obtained equations and assist the design. Practical results are given to illustrate the accuracy of theoretical predictions with measured magnetic field curves.

Domotics Project Housing Block

This document develops the study of an implementation project of a home automation system in a housing placed in the town of Galapagar, Madrid. This house, which is going to be occupied by a four-member family, consists of 67 constructed square meters distributed in lounge, kitchen, three bedrooms, bath, bathroom and terrace, this being a common arrangement in Spain. Thus, this study will allow extracting conclusions about the adequacy of the home automation in a wide percentage of housing in Spain. In this document, three house automation proposals are developed based on the requirements of the client and the different home automation levels that the Spanish House and Building Automation Association has established, besides two parallel proposals relating to the safety and the technical alarms. The mentioned proposed systems are described by means of product datasheets and descriptions, distribution plans, measurements, budgets and flow charts that describe the functioning of the system in every case. An evaluation of each system is included, based on other studies conclusions on this matter, where expected energy savings from each design, depending on the current cost of lighting, water and gas, as well as the expected economic amortization period is evaluated.

Technique of magnetic labels production for security systems

Flash annealing techniques have been used to crystallize locally amorphous materials and so to obtain samples that present alternatively soft and hard zones with application in magnetic labels for security systems. On the other hand, we show that by controlling adequately the local flash annealing, it is possible to obtain materials with different ratios between the first and third harmonic of the induced signal in a detecting coil, that can be used to codify the magnetic labels.

Crystallization study during DC Joule heating in amorphous ribbons

A study of the temperature dispersion during current annealing of amorphous ribbons was done. The local temperature was obtained by measuring the local infrared emission during the thermal treatment. The results exhibit a nonuniform macroscopic distribution of temperatures during the current annealing. In this work, we have developed a theoretical model of the crystallization in the sample during the annealing that confirms the results obtained.

Mathematical Model Switched Reluctance Motor

This paper describes a mathematical model of switched reluctance motor (SRM). The mathematical model of the SR motor is nonparametric and can only be established with experimental data, instead of an analytical representation. Because the reluctance varies with rotor position and magnetic saturation is part of the normal operation of SR motors, there is no simple analytical expression for the magnetic field produced by the phase windings. The shape of phase current before commutation is of interest because it varies widely depending on when the phase winding is excited and what the rotor speed is. To illustrate this effect, two step response simulations were done here in Matlab/Simulink. The SR motor model used in these two simulations is a 6/4 linear magnetics model, the same structure as the experimental SR motor. For the first simulation, a step voltage is fed into phase A and the initial rotor position is set to be 1o instead of 0o so that the rotor will move in the positive direction. The results show that the rotor stops at 45o after some oscillation which is the aligned position of this phase A. For the second simulation, a step voltage is fed into phase C. The initial position is 0o. According to this, the rotor will move towards the aligned position of phase C, i.e. 15o.

New System for Measuring Impact Vibration on Floor Decking Sheets

Currently, there is a narrow range of materials that are used as attenuators of impact noise and building vibrations. Materials used in construction, such as elastic materials, must meet the requirement of having very low elastic modulus values. For the determination of the materials elastic modulus and the acoustic insulation of the same, costly and difficult to execute testing is required. The present paper exposes an alternative system that is simpler and more economic, consisting of a predefined striking device and a sensor able to determine, once the strike is produced, the energy absorbed by the plate. After the impact is produced, the plate undergoes a deformation, which absorbs part of the energy, the remaining part being transmitted to the slab and, at the same time, causing induced airborne noise in the adjoining room. The plate absorbs the power through its own deformation, which is measured with the help of a capacitive sensor. This way, it would be possible to properly define the geometry of the plates, after the execution of the test, and we will try to establish a relationship between the values proposed in this research and the acoustic behavior demanded by the Spanish standards.