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International Review of Electrical Engineering - December 2007 - Papers

 

   

 


 

International Review of Electrical Engineering - Papers

go to top    The “Evaluator” Suite for the Computer-aided Analysis of Advanced Automotive Electrical Power System
        by S. Meo, F. Esposito

      Vol. 2. n. 1, pp. 751-762

 

Abstract - In the last years, the on-board electric power requirement in vehicles is continuously increasing. The increase in power demand is even due to emerging automotive technologies such as variable engine valve, active suspension, x-by-wire (e.g. steering-by-wire, brake-by-wire, etc.) and heated catalytic converter. Since the adaptability of the conventional electrical system to the needs of next future and present electrical loads is very little, alternative architectures of powernet are required, but it isn’t still clear how to detect the best architecture for a fixed automotive application.
The goal of this paper is to introduce a new computer aided technique for the choice of new architectures oriented for advanced automotive applications. The paper presents the software suite EVALUATOR to compare different electrical power systems and to identify which of them has superior performances and is economically competitive.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: optimization techniques, expert systems applications, automotive electrical power system

 


 

go to top    Power Cables Models with Frequency Dependent Parameters
 
        by Y. Weens, N. Idir, J. J. Franchaud

     Vol. 2. n. 1, pp. 763-770

 

Abstract - The fast commutation of the modern power semi-conductor devices is the main source of the conducted and radiated emissions generated by the power converters. These devices produce high voltage variations (dv/dt) which excite stray elements of the power circuit and induce high frequency parasitical currents that use the energy cables to be propagated in the whole of the system.
In order to study the influence of the power cable characteristics on the level of the conducted emissions, it is necessary to elaborate a precise model of the energy cables, taking into account various phenomena that appear when the frequency increases.
This paper proposes a high frequency modelling method of energy cable that takes into account the skin and proximity effects and dielectric losses. The proposed method is applied to the 3-wire unshielded cable and extended to the 4-wire shielded cable. The proposed models are validated in the frequency and time domains.

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Keywords: Power cables, Modeling, Power electronics, Adjustable speed drives, EMI.

 


 

go to top    A Comparative Study of IEC 61000 Part 3-2 & 3-4 and IEEE 519-1992 Standards in Low Voltage Applications

        by C. Benachaiba, B. Ferdi

  Vol. 2. n. 1, pp. 771-776

 

Abstract - A survey of the two widely used standards of current harmonic limits is presented. The first is the International Standard IEC 61000 part 3-2 & 3-4 which is adopted by the European Union as EN 61000 part 3-2 & 3-4, and the second is the standard IEEE 519-1992 which has been widely adopted, particularly in North America. After providing an understanding of the two standards, two different examples are given to compare their current harmonic limits and the practical differences between them are clearly explained. At the end, new current harmonic limits that satisfy the two standards are suggested.

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Keywords: Current Harmonic Limits, IEC 61000-3-2, IEC 61000-3-4, IEEE Std 519-1992.

 


 

go to top    Effect of Transient Impedance of a Lossy Ground on Horizontal Electromagnetic Field Due to Inclined Lightning Strokes

        by L. Boukelkoul, S. Leulmi, H. Benalla

         Vol. 2. n. 1, pp. 777-781

 

Abstract - Evaluating the electromagnetic fields very close to lightning strokes has been widely studied. The electromagnetic fields generated by the lightning are strongly affected by the inclination of the channel and the ground impedance. For the inclined channel particularly the very near fields, the literature show poor approach for such problems. While the vertical electric field is less affected by ground effects, the horizontal field is strongly affected, varying from zero at the ground to a negative value.
In this paper, the effect of ground is taken into account in the calculation process of the amplitude of the electromagnetic fields in the early instants of the stroke.
Using a simple method for calculating the magnetic field by considering the lightning stroke as an infinitely long filament, the electric field is then calculated by simply discretising the Ampere’s law. The results show that the channel inclination and the ground impedance affect markedly the fields at close distances.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Lightning stroke, Electromagnetic Fields, Channel Inclination, Ground Impedance.

 


 

go to top    Finite Element Method for the Prediction of Magnetic Fields and Losses in Three Phase Underground SF6 Insulated Cables

        by S. Sadeghi, M. Jalalifar, A. H. Isfahani

         Vol. 2. n. 1, pp. 782-786

 

Abstract - This paper presents a finite element method for predicting magnetic field above ground, generated by an underground SF6 insulated cable as well as its eddy current losses. First, with the aid of Ansys software the magnetic field in underground SF6 insulated high voltage cables under and above ground is computed and then, currents and losses in the shields of the cables are computed. The influences of the operating parameters on these quantities are also examined.

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Keywords: SF6 insulated cables, Magnetic field, Losses, Finite element method.

 


 

go to top    Monitoring State-of-charge and State-of-health of VRLA Batteries Using Impedance Spectroscopy: Experimental Analysis
        by F. Lakhdari, A. Midoun

         Vol. 2. n. 1, pp. 787-792

 

Abstract - In this paper the impedance measurements of 24Ah valve regulated lead acid batteries are reported and analyzed. The monitoring process is performed using a designed and tested laboratory spectroscope during discharge process. The tests are done with constant rates within the range C/200 to C/5 and under ambient temperature. A simplified impedance model is used according to the relatively high excitation frequency range exploited (from few Hz to several kHz). Using the obtained results we would discuss the eventual correlation between battery impedance and its state of charge (SOC) and its state of health (SOH). The investigation clearly reveals the mainly resistive behaviour of the battery impedance. However even if the internal resistance is found to be function of the battery state of charge, a large part of this profile is found to be quasi-flat. Moreover the high influence of plate’s pore blocking process strongly related to the cycle rate is confirmed. A last set of extensive tests performed during a long period time have clearly shown that high frequency impedance could be an efficient battery state of health indicator since all battery history is stored in its variation.

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Keywords: VRLA batteries, impedance spectroscopy, state of charge, state of health, internal resistance.

 


 

go to top    Analysis of Operation of Symmetrical Dual Three-Phase Converters with Hybrid Schemes of Synchronised PWM

        by V. Oleschuk, F. Profumo, A. Tenconi

         Vol. 2. n. 1, pp. 793-802

 

Abstract - New method of synchronised pulsewidth modulation (PWM) has been applied for control of six-phase (dual three-phase) converter feeding symmetrical induction motor which has two sets of windings spatially shifted by 60 electrical degrees. Basic schemes of synchronised continuous and discontinuous PWM, disseminated for control of symmetrical systems, have been analyzed and compared. It has been shown, that combined (hybrid) schemes of synchronized PWM provide better weighted THD factor of the useful components of the phase voltages in comparison with the identical (continuous+continuous or discontinuous+discontinuous) schemes of PWM in symmetrical dual three-phase systems. Simulation results show the behavior of symmetrical six-phase converters with low switching frequency, controlled by algorithms of synchronised PWM. Special attention has been given to analysis of synchronous smooth control of symmetrical six-phase systems in the zone of overmodulation.

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Keywords: Dual Three-Phase Inverter, Space-Vector Modulation, Voltage Synchronization.

 


 

go to top    Effect of SiC Diodes on Power Losses of the Voltage-Source Shunt Active Power Filter

        by M. Routimo, H. Tuusa

        Vol. 2. n. 1, pp. 803-813

 

Abstract - A major drawback of the silicon (Si) diodes used in power electronic applications is the high reverse recovery current causing high switching losses which constitute a significant proportion of the total power losses in the pulse-width-modulated semiconductor bridge. An attractive alternative to the silicon diodes are Schottky barrier diodes fabricated in silicon carbide (SiC). SiC diodes offer several benefits, such as greatly reduced switching loss and higher junction temperature over their silicon counterparts.
This paper studies the use of silicon carbide Schottky diodes in the voltage-source shunt active power filter. The Si diodes of the conventional three-phase bridge are replaced with their SiC counterparts to determine their effect on the semiconductor bridge power losses. The power losses are first determined by calculations and the distribution between the conduction and switching losses is estimated. Finally, measurements are performed to verify the results. The results show that by using SiC components examined the semiconductor losses are decreased about 20 %.

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Keywords: Active filter, semiconductor losses, switching losses, silicon carbide, SiC.

 


 

go to top    Steady State Characteristics of the Off-Duty Cycle Controlled APFC with No Input Voltage Sensing
        by A. Abramovitz

       Vol. 2. n. 1, pp. 814-819

 

Abstract - This paper presents analysis of steady state characteristics of Average Current Mode Boost Active Power Factor Corrector (APFC) with no line voltage sensing. Expressions for APFC's steady state transconduction, output resistance and power gain performance indexes are derived. The theoretical predictions are well supported by simulation and experimental results.

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Keywords: AC-DC conversion, PFC.

 


 

go to top    A New Fixed Frequency Hysteresis Current Controller Suitable for Wind Energy Sources
        by R. Garcia-Retegui, S. A. González, M. Benedetti, R. García-Gil, J. M. Espí, J. Castelló

       Vol. 2. n. 1, pp. 820-826

 

Abstract - This paper introduces a new current controller (CC) used for grid-connected inverters suitable for wind-turbine applications, which is based on the hysteresis current control (HCC) technique. This CC improves the main HCC drawback, by working at constant switching frequency and has a slight interference among phases in 3-phase systems with isolated neutral. It has been fully implemented in a single DSP of Analog Devices (ADSP-21992), with the only requirement of a zero crossing detector (ZCD) and with no extra circuitry such as DACs or ADCs. Main steady-state and dynamic response of the proposed control are discussed in this paper, showing a good current reference tracking with minimum steady-state error and with the least possible transient time.

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Keywords: Digital Current Control, Voltage-Source Inverters, variable speed wind turbine.

 


 

go to top    Direct Torque Control Strategy Based on Constant Switching Frequency Applied in Current Source Inverter Fed Induction Motor Drive
        by A. B. Nikolic

       Vol. 2. n. 1, pp. 827-834

 

Abstract - The new direct torque control (DTC) strategy based on constant switching frequency of current converter fed (CSI) induction motor drive is presented. The goal of this work is to obtain better performances than exist in similar vector controlled drive, but with reduced control structure and its simpler implementation in the microprocessor system. Contrary to the direct torque control of CSI drive presented in the known literature without experimental results, proposed algorithm is based on constant switching frequency with modification of the inverter optimal switching table. With such a solution, problems detected under DTC using torque hysteresis controller are avoided (significant torque pulsations, requirement for filtering estimated torque and adaptation of hysteresis bandwidth in depend of motor speed). Performance analysis of the recommended control algorithm is tested by PC simulations and through implementation in the realized drive prototype with a standard thyristor type frequency converter.

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Keywords: DTC, CSI, induction motor.

 


 

go to top    Artificial Neural Network Used to Determine Self and Cross-Saturation Effects on the Salient Pole Synchronous Generator
        by W. Bahloul, N. Gasara, M. B. A. Kamoun

       Vol. 2. n. 1, pp. 835-841

 

Abstract - This paper presents a new technique for measuring synchronous generator reactances. A few operating data are used then are mapped by the Artificial Neural Network (ANN) for making a large data basis. First an (ANN) based technique is used to estimate the rotor angle and field current function of the generator inputs. The developed ANN models are validated with real measurements not used in the training procedure. Subsequently, the self and cross-saturation saturation curves of the direct and quadrature axis magnetizing reactances are identified using Blondel Method.

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Keywords: Synchronous generator, Artificial Neural Network, Blondel Method, Cross-saturation, parameter estimation.

 


 

go to top    Diagnostics of Induction Machines with Incipient Rotor Cage Faults Using the Neutral Voltage
        by A. Khezzar, M. E. K. Oumaamar

      Vol. 2. n. 1, pp. 842-848

 

Abstract - Most of rotor related faults in three phase induction motors are due to broken rotor bars and end rings. The approach used in this paper to detect incipient broken rotor bars is based on the analysis of the voltage taking place between the supply and the stator neutrals. Broken rotor bars cause asymmetries in the mutual inductance of the machine, which give rise to harmonic components in the neutral voltage. In this work a theoretical analysis is proposed in order to depict all harmonic components related to the rotor defects. The examination of these harmonics shown to enclose reliable information on the condition of the machine, from which a generalized formula has been developed. Experimental and simulation results obtained confirm the aforementioned study.

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Keywords: incipient fault, broken rotor bars, induction machine, neutral voltage, diagnosis.

 


 

go to top    Electromagnetic Characteristics of the RFID System in Proximity to Metal
        by F. A. Mohammadi, S. R. Ailani

      Vol. 2. n. 1, pp. 849-853

 

Abstract -  The objective of this work was to investigate the fundamental electromagnetic characteristics of the Radio Frequency Identification systems i.e. RFID systems in proximity to metal in order to improve performance and/or range of RFID system. The simulation efforts have been concentrated on how the flux is affected by the metallic disc. A finite element electromagnetic model has been developed to predict magnetic field distribution. This model consisted of a reader coil, a circular metallic disc and a tag coil. Various configuration sets have been considered. For each configuration the magnetic field distribution of desired locations of RFID system has been calculated; taking the eddy currents into consideration. The obtained results have been presented and the performance of RFID tags in presence of metals was examined.

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Keywords: RFID, Inductive Coupling, EM Modeling, Finite Elements Method, Compatibility.

 


 

go to top    Evaluation of Lettuce Growth Under Multi-spectral-component Supplemental Solid State Lighting in Greenhouse Environment
        by P. Pinho, R. Lukkala, L. Särkkä, E. Tetri, R. Tahvonen, L. Halonen

      Vol. 2. n. 1, pp. 854-860

 

Abstract -  Light-emitting diodes (LEDs) have been useful in evaluating plants’s physiologic and growth responses to radiation quality and quantity. In the great majority of these studies, growth rooms (phytotrons) have been used in order to avoid the influence of external factors such as the daylight radiation. The main objective of this study was to evaluate the growth performance of two LED-based supplemental lighting treatments (LED1, LED2) on lettuce (Lactuca sativa var. crispa L., ‘Frillice’) cultivation in real glass greenhouse conditions. Control plants were grown under conventional high-pressure sodium (HPS) lamps. In LED1 treatment red-orange (RO) and blue LEDs with peak wavelength emissions at 630nm and 460nm, respectively were used while in LED2 an additional yellow component at 594nm was also included. The results had indicated that lettuce growth parameters can be improved using supplemental spectral-tailored LED lighting. RO LEDs were also effective in promoting biomass accumulation and the addition of a small percentage of yellow photons may further enhance this aspect and increase the number of leaves per plant. The results have also suggested a relation between the amount of blue photons and yellow-green photons in lettuce growth.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Light-emitting diodes, supplemental lighting, greenhouse, lettuce, energy efficiency.

 


 

go to top    Continuous Time Controller Based on SMC and Disturbance Observer for Piezoelectric Actuators
        by S. Yannier, A. Sabanovic

   Vol. 2. n. 1, pp. 861-869

 

Abstract -  In this work, the analog application for the Sliding Mode Control (SMC) to piezoelectric actuators (PEA) is presented. DSP application of the algorithm suffers from ADC and DAC conversions and mainly faces limitations in sampling time interval. Moreover piezoelectric actuators are known to have a very large bandwidth that is close to the DSP operation frequency. Therefore, by means of the direct analog application, the improvement of the performance and a high frequency operation are expected. The design of an appropriate SMC together with a disturbance observer is suggested to have continuous control output and related experimental results for position tracking are presented with a comparison of DSP and the analog control application.

Copyright © 2007 Praise Worthy Prize S.r.l. - All rights reserved

 

Keywords: Sliding Mode Control, Disturbance Observer, Piezoelectric Actuator, Analog Electronics.

 



 
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