Luminita Mirela Constantinescu

Evaluation of the performance of new extremum seeking control algorithm to locate accurately the peaks on multimodal functions

A new Extremum Seeking Control (ESC) scheme is proposed in this paper for multimodal function with two dimension (2D), named as ESC 2D — scheme. This ESC 2D-scheme is a Single Input — Double Outputs (DISO) control system that combine two ESC 1D-schemes of asymptotic perturbed type. Each ESC 1D-scheme has two control loop. The scanning loop generates the signal that sweep the searching space in order to locate the desired peak on the multimodal pattern. The tuning parameter (k2) will define the space of searching. The locating loop generates the gradient signal that will find accurately this peak. The tuning parameter (k1) will define the searching speed under the constraint of stability of the ESC loop. The performance obtained for the ESC 2D scheme proposed is evaluated on multimodal benchmark patterns.

Computation of the characteristics of a claw pole alternator through the finite element method

The paper presents the analysis of a 3-D numerical model developed for a claw pole alternator. The complex structure of the claw-pole magnetic circuit required a 3D FEM model and a double scalar potential magnetic φ-φred formulation, in order to reduce computing time and memory. The no-load and magnetization characteristics and the e.m.f. time dependence have been calculated. Working characteristics and the induced voltage in the static winding can be calculated by knowing the 3D distribution of the field in stationary magnetic regime for successive positions of the rotor considering the stator.

A LiFePO 4 battery discharge simulator for EV applications — Part 1: Determining the optimal circuit based battery model

This paper, the first of a series of papers on developing a LiFePO4 (LFP) battery discharge simulator for EV applications, presents a new strategy for determining the optimal circuit based battery model. The proposed methodology has the fallowing novel features: a new test for establishing the performances of the model and a multi-criteria analysis for determining the optimal number of resistor-capacitor branches. Then the model is validated using data from a LFP battery submitted to discharge in concordance to a driving cycle.

On the search speed for the Extremum Seeking Control 2D-schemes. Part II - performances estimation

In this paper a performances analysis of the Extremum Seeking Control (ESC) scheme applied to the dual-inputs single-output (DISO) systems is presented. These ESC 2D-schemes contain two ESC 1D-schemes that have a common input: the output of the DISO system. The performance of the basic high-order ESC (bhoESC) and band-pass filter ESC (bpfESC) 2Dschemes will be analyzed here based on the two orthogonal dither signals. The ratio of the search speeds for these 2D-schemes is estimated analytically during the search speed based on the partial derivatives of the unknown DISO map. The relation of the search speeds ratio related to these partial derivatives and control parameters of the ESC 2D-scheme is shown. The proposed bpfESC 2D-scheme has higher search speed than the bhofESC 2D-scheme, and this is clearly highlighted in this paper based on the simulation performed.

Computation of the characteristics eddy current electromagnetic brake for a bicycle, by the finite element method 3D

The paper presents numerical and experimental study of the eddy current brakes, used to produce braking torque of a medical bike. Complex structure and lack of symmetry plane parallel geometry required the development of 3D numerical models to calculate the magnetic field. They allow determination of overall brake performance and design optimization to increase braking torque and to reduce volume. 3D numerical models developed on the basis of finite element method are models of transient magnetic system for determining induced currents in the disk. In solving problems field, it was used the formula TФ-Фr. Thus in the region of the disk were used electric vector potential T and total magnetic scalar potential Ф, in regions of the core magnetic total scalar magnetic potential Ф, and in areas of air forms in Фr reduced scalar magnetic potential.

Modeling the charging characteristics of storage batteries for PV power systems

This paper presents a numerical method in order to measure and analyze the charging characteristics of storage batteries for PV power systems. The measurement data is retrieved from the PV modules by a specific data acquisition system. A numerical algorithm developed in the Matlab/Simulink environment is used to model the charging characteristics of the batteries connected to a PV system. Through the interpolation method, the polynomial functions of total battery current and battery state of charge depending on time and illumination are obtained. The numerical values of the errors between the theoretical and experimental results prove the accuracy of the proposed method.

On the search speed for the Extremum Seeking Control 2D-schemes. Part I - signal processing using orthogonal dither signals

In this paper an analysis of the Extremum Seeking Control (ESC) 2D-scheme for the dual-inputs single-output (DISO) systems is presented. The ESC 2D-schemes have two loops where the output signal is obtained based on two different ESC algorithms proposed in the literature. The basic high-order ESC (bhoESC) 2D-scheme and an improved ESC variant will be analyzed here based on the two orthogonal dither signals. The proposed ESC scheme is based on a band-pass filter (BPF) instead of the series combination of high-pass (HP) and low-pass (LP) filters used in the bhoESC scheme. The processing of the output signal shows that the search speed in both bpfESC loops depends on the BPF cut-off frequencies. So, besides the gradient signals, the injected signals on the both bhoESC inputs contain the Low Frequencies (LF) components from the BPF band. Thus the dither persistence in the bpfESC loops is improved in comparison with the bhoESC scheme. The relations between the search speeds and the partial derivatives of an unknown DISO map are shown.

Electrical Power Systems

The general description of architecture and classification of power systems are presented at the beginning of the first chapter. Afterwards the basic concepts and analysis methods of electrical power systems are given, being accompanied by many examples of calculation. Also the power flow between the generators and consumers has been considered. In order to characterize the parameters of power systems next section of the first chapter is dedicated to measurement methods of power systems parameters. Electrical energy needed to power industrial or household electric consumers, like any other product, should satisfy specific quality requirements. In this respect the power quality aspects and the standards for power systems parameters are presented. The flow of reactive power and energy in power systems produces significant effects on the optimal functioning of suppliers and customers which are connected. Therefore in the last section of first chapter is defined the importance of reactive power in AC power systems and on its various understandings. Usually the first chapter is closed with a large list of bibliographic references.

A LiFePO 4 battery discharge simulator for EV applications — Part 2: Developing the battery simulator

This paper, the second of the series on developing a LiFePO4 (LFP) battery discharge simulator for EV applications, presents an approach for developing the battery simulator. After the optimal battery model was established, in the first paper, the main drawbacks of battery simulator are addressed and a new strategy is proposed. This strategy uses neural networks (NN) for online estimation of the battery parameters during discharge. The proposed simulator is validated by comparisons with a typical simulator and data from a LFP battery submitted to discharge profile in concordance with a driving cycle.

Electrical power analysis learning and implementation in One2One project

This paper presents a didactical project for vocational education in electrical field under the European Longlife Learning Programme - Transfer of innovation - with the title “one2one - One Teacher and One Student working with ProjectX [1], [2]”. The ProjectX is an innovative methodological guidebook for the student to carry out a concrete work, one to one with the tutor, in which theory and practice are both thoroughly integrated and is related to the real workplace [1], [2]. In the theoretical part, students will learn about the key elements of an electrical installation that refers to: the main types of loads, the electrical system capacity, the cables choice, checking the protection of electrical equipment, protection of persons, power factor and harmonics. They will also know the parameters for estimating main characteristics of electrical networks. After learning and testing, the students will perform the practice that has as main objective the achievement of energy assessments. At the end of this ProjectX, students will be able to realise a preventive or corrective maintenance for best energy efficiency, with high technical and economic impacts. The Project developed by France partner was evaluated by Romania partner, in order to improve its quality and transferability. In these conditions the project facilitates the exchange of ERASMUS mobility for students and teachers.