All posts by cburada

Impact of Experimental Measurements Accuracy on Validation Process of Crimped Connections

Abstract

In the process of validation of crimped connec-tions, the determination of the connector resistance factor and of the initial scatter coefficient has a decisive role. In this paper is studied the impact of the experimental meas-urements accuracy on the calculation of initial scatter, cu-mulating data from various types of crimped connections. This coefficient provides information on the behavior of the crimped connection immediately after installation before any aging effect begins. The standards establish that 6 sam-ples are sufficient to be tested to estimate the identification of a “family” of connectors. The measurements were per-formed on crimped connections of barrel of terminal lug type for three cross sections of cables and on crimped con-nections of bimetallic through connector type for two pairs of cross sections. The initial scatter is influenced by 6 repre-sentative measured quantities as voltage drops, currents and conductor lengths. First, it was imposed a variation by one unit of hundredths digit of initial scatter and was recorded the variation of each quantity, the others 5 quantities being kept constant. Then simultaneous variations of the 6 quanti-ties caused by device reading errors were imposed, deter-mining the quantities with the greatest influence on initial scatter. Useful recommendations for experimenter are made. images

Application of the Rotor Field-Oriented Control for an Induction Motor Used in Electric Traction

Abstract

In this paper, the rotor field-oriented control is applied for a three-phase induction motor used in electric traction of an autonomous locomotive powered by a battery. First, the operating equations in the rotor field-oriented system are introduced. Then, the control scheme based on the structural scheme and operational equations are pre-sented. After referring to the design of the controllers, the performances of the control system during the start-up pro-cess by prescribing a ramp speed and step rotor flux are addressed and analyzed. Four values of the prescribed speed are taken into consideration. Through the presented results, the synthesis of the control system and control algorithm are validated. images

Wireless Transfer of Electric Power - a Disruptive Technology

Abstract

Wireless (contactless) transfer of electric power is a disruptive technology because it abandons wired transmission technology, the only technology used in electrical and electronic engineering until recently, just like in the past animal traction and film photography were replaced by mechanical traction and digital photography. Although revealed at the end of the nineteenth century through Tesla’s inventions, it could be applied in practice only in the ‘80s of the twentieth century, with the development of power electronics and microprocessors. After an introduction and an overview of the operating principles, the paper presents the readiness level reached by this technology, the stage of standardization, Romanian achievements and future prospects for high power applications. images

Annals of the University of Craiova, Series : Electrical Engineering, No. 45, Vol. 45, 2021

ANNALS OF THE UNIVERSITY OF CRAIOVA – Electrical Engieneering Series, no. 45, vol. 45, Issue 1, 2021 (click to download)

Wireless Transfer of Electric Power – a Disruptive Technology – Andrei Marinescu

Application of the Rotor Field-Oriented Control for an Induction Motor Used in Electric Traction – Mihaela Popescu, Alexandru Bitoleanu, Constantin Vlad Suru

Impact of Experimental Measurements Accuracy on Validation Process of Crimped Connections – Alin-Iulian Dolan, Constantin-Florin Ocoleanu

Real-Time Sensorless Control of the PMSM based on Genetic Algorithm, Sliding Mode Observer, and SCADA Integration – Claudiu-Ionel Nicola, Marcel Nicola, Maria-Cristina Niţu, Dumitru Sacerdoţianu, Ancuța-Mihaela Aciu

The Choice of the Main Power Components in Electric Traction Converters – Lavinius Sorin Goreci, Mihaela Popescu, Ion Tilă

Optimization of Electromagnetic Devices using a RSM Enhanced ACOR Algorithm – Anton Duca, Bianca Lamba

Comparative Analysis of Two Methods of Calculating the Prescribed Current in a Shunt Active Filtering System – Mihăiță Daniel Constantinescu, Mihaela Popescu, Constantin Vlad Suru

Automatic Ventilation and Air Conditioning System for Educational Training – Ionel Laurenţiu Alboteanu, Andrei Cosmin Militaru

Considerations on the Disturbances Occurred in the Operation of Medium Voltage Electrical Networks with Neutral Treated by Suppression Coil – Silvia-Maria Digă, Nicolae Digă, Paul-Mihai Mircea, Ion Marin

Experimental Study of HBC Fuses with Aluminium Fuse Element at Minimum Rated Breaking Current, Maximum Rated Breaking Current and Transfer Current of Fuse-Switch Combination – Cristian-Eugeniu Sălceanu, Marcel Nicola, Daniel Ocoleanu, Daniela Iovan, Sorin Enache

Simulation of Multi-Motor Propulsion System for Energy Efficiency in Electric Vehicles – Cristian-Liviu Popescu, Laureţiu Marius Dumitran, Alexandru Stănescu

Ways to Determine the Structural Resource of Highly Maneuverable Aircraft – Nicolae-Alin Niculescu, Jenica-Ileana Corcău, Nicuşor Cătălin Stancu

Two Numerical Studies for Longitudinal Movement of a Canard UAV with Vectored Thrust – Liviu Dincă, Jenica-Ileana Corcău, Dionis Cumpan

Annals of the University of Craiova, Series : Electrical Engineering - 2020

The Use of Helmholtz Coils Designed for 50 Hz at Higher Frequencies – Georgiana Roşu, Ionel Dumbravă, Ion Pătru, Aurelia Scornea, Octavian Baltag, Andrei Marinescu

Wireless Remote Control for the Anti-Hail Missiles Launch Ramp Positioning System – Sorin Stepan, Gheorghe Manolea

Influence of Synchronized Measurement Errors on the Results of Identification of the Transmission Line Parameters – Murdid Ecaterina, Boris Jingan, Dobrea Ina, Vasilos Elena

Metamaterials – Current and Future Trends – Elena Helerea, Lia- Elena Aciu

Virtual Instrumentation for Study of Shape Memory Alloys Strip while Bending – Gheorghe-Eugen Subţirelu, Sonia Degeratu

Aspects Regarding the Impact of Electrical Vehicles’ Charging on Power Quality – Denisa Ruşinaru, Gabriel Cosmin Buzatu, Leonardo Geo Mănescu, Claudiu Popirlan

‘Open Ended’ Laboratory to Study the Influence of Unit’s Weight on Axle Torque in Railway Traction – Petropol Şerb Gabriela Dana, Petropol Şerb Ion

Constructive Dimensions Optimization for Asynchronous Motors used in Coal Mills – Raluca-Cristina Presură (Nicolae), Sorin Enache, Ion Vlad, Marian-Ștefan Nicolae

Program for Monitoring Operation Regimes of Low-Power Electrical Machines – Sorin Enache, Ion Vlad, Monica-Adela Enache

Contributions Regarding the Monitoring in the Command Center of the Anti-Hail Launch Pads – Sorin Stepan, Gheorghe Manolea

Modeling of Thermal Comfort Parameters in Residential Buildings – Radu-Cristian Dinu, Daniela Popescu, Ioana-Gabriela Sîrbu, Dan-Gabriel Stănescu

Studies on the Command of Single-Phase Rectifiers Using the Scalar Control Technique – Florin Alexandru Teodorescu

ANNALS OF THE UNIVERSITY OF CRAIOVA – Electrical Engieneering Series, no. 44, vol. 44, Issue 1, 2020 (click to download)

Studies on the Command of Single-Phase Rectifiers Using the Scalar Control Technique

Abstract

One of the important problems of power supply systems consists in ensuring the quality of energy supplied to consumers. In this issue, the reduction of the harmonic spectrum of the supplied voltage and current has a key role. As electronic power converters are now increasingly used by consumers, the problem of reducing the harmonic spectrum of the current absorbed by the power supply by these consumers is becoming more and more pronounced. For this, there is the problem of using consumers with a power factor as close as possible to the unit, which also ensures the increase of the efficiency of these consumers. The present paper focuses on the study of single-phase rectifier configurations provided with power factor control (PFC) structures. Among the multiple techniques and methods of power factor control, the scalar power factor control technique was applied to a boost type power converter, in two variants. The first variant is that of a single-phase rectifier in fully controlled bridge. The second is that of a single-phase rectifier in uncontrolled bridge. In both cases, the study of the scalar PFC technique was based on the Matlab/Simulink modeling of the two mentioned configurations. Achieving these models allowed the study of the correction mechanism of the power factor under the influence of the various functional parameters of the approached configurations. images

Modeling of Thermal Comfort Parameters in Residential Buildings

Abstract

At the level of residential buildings, current studies and research are focused on issues that have as a main priority, the energy of buildings. Energy efficiency of buildings involves, in addition to technical regulations and energy rehabilitation works, an economic optimization of energy in buildings. This optimization must not be done at random, but we must ensure that the conditions of thermal comfort inside the building are met at all times. In this paper, the object of the study is a room located in the middle of a condominium building in Craiova. The building of which the studied room is part is located inside the locality and has constructive structure of the tire elements, characterized by specific thermal resistances of the construction materials used. The mathematical model involves determining the values of thermal comfort parameters (indoor temperature, average radiation temperature, etc.) and their implementation in the calculation of the thermal comfort index, B. The results obtained for the three categories of rooms, allow the feeling of comfort to be included in one of the seven levels. Between the three types of studied rooms there are differences of the calculated interior temperatures, due to the temperature differences on the faces of the construction elements. images

Contributions Regarding the Monitoring in the Command Center of the Anti-Hail Launch Pads

Abstract

This paper describes an Internet-connected radio remote control designed for the positioning system of the launching pad of anti-hail missiles used by the Romanian Anti-Hail System. The remote control works on the ISM band of 433 MHz and was successfully tested on a small size experimental model of the launch pad. The azimuth and elevation position can be locally controlled by the operator, with the possibility of monitoring and even controlling the launch pad from the Command Center, over the Internet. The remote control uses a touch screen display on the opera-tor side and a PLC connected to the launch pad. The commands on the touch screen are grouped into three pag-es: manual positioning, automatic positioning, and a list of recorded events. Sending the coordinates to the launch pad and firing the missiles are considered events, automatically recorded on an SD card or USB flash drive attached to the remote control. Communication between the touch screen and the PLC is realized by two RF transceivers using LoRa modulation. The touch screen display is connected to the Internet, making it possible to remotely monitor and control the launch pad using an Internet-connected computer. The access to the remote control is password protected and can be disabled by the local operator. images

Program for Monitoring Operation Regimes of Low-Power Electrical Machines

Abstract

In this paper there are presented details about a program for monitoring steady states and dynamic regimes of low-power electrical machines. The program allows viewing the variation waves of the main electrical quantities, their harmonic content and the relative position of the characteristic phasors. The program advantages are mentioned and there have exemplified some data acquisitions, carried out for a few concrete situations. The main work windows from the Instrument menu are detailed. There have also been presented the results obtained by monitoring the operation of two motors, a three-phase asynchronous motor with single-phase supply and a single-phase asynchronous motor. A part of the conclusions obtained could be mentioned as follows: a) for the case of three-phase asynchronous motor with single-phase supply, we noticed that a voltage increase leads to an increase of the inductive phase shift of the current I1, the phase shift of the current I2 (measured on the phase in series with the capacitor) remains practically unchanged, the capacitive phase shift of the current I3 increases and the distortion degree of the current I1 decreases; b) for the case of the single-phase asynchronous motor we noticed that in load operation (at rated voltage) a decrease of the phase shift between the current and voltage corresponding to the main winding occurs and the current distortion degree increases when the load increases. The paper ends with conclusions and references. images

Constructive Dimensions Optimization for Asynchronous Motors used in Coal Mills

Abstract

The high operating cost, owed to the large consumption of active and reactive power, led to the optimization of the design and construction of asynchronous motors used in driving the coal mills. The reduction of the operating cost is a difficult problem, because the motor usually lies in a closed enclosure, with provided gauge dimensions, and with specific requirements imposed by the type of drive in use. Using this information, while keeping the existing electromagnetic stresses (for heating reasons), the optimal construction dimensions can be established by design, so as to reduce the operating cost. The optimization is substantiated by the decrease of the operating cost of such a motor with 26100 euros, as compared to the existing version. images