Emre Çelik

Application of Genetic Algorithms to Core Loss Coefficient Extraction

Core loss data are usually provided in the form of tables or curves of total loss versus flux density or frequency for electrical machine designers. These tables or curves can be used to extract the loss coefficients of the core loss formulas because accurate calculations of the coefficients have an important issue in electrical machine design. In this study, using original loss data given for M19 steel material, the core loss coefficients are calculated by the genetic algorithm developed in Matlab environment and electromagnetic analysis software (Ansoft Maxwell) is also used to extract the core loss coefficients in order to verify the proposed method. It is found that the exponent of flux density (B) depends on the flux range or the frequency range and these changes in the exponent of B can be correlated to the physical phenomenon of domain wall movement in response to an external field. As a difference from existing studies in literature, this study suggests a new method for extracting the core loss coefficients without any requirement for mathematical operations due to the nature of genetic algorithms and over the range of frequencies between 50–400 Hz and flux densities from 0 to 1.5 T, the new method yields lower errors for the specific core losses than those obtained by the magnetic field analysis software.

An Educational Tool for the Genetic Algorithm-Based Fuzzy Logic Controller of a Permanent Magnet Synchronous Motor Drive

In this study, a novel educational tool is introduced for the genetic algorithm (GA)-based fuzzy logic controller (FLC) of a permanent magnet synchronous motor (PMSM) drive. This tool provides the operating principle of PMSM, essentials of GAs, and effects of FLC parameters on the performance of GA-based FLC. The proposed educational tool regarding GA-based FLC is a unique one in its field in the literature, as such a computer-based study aiming to teach the corresponding intelligent system has not been studied before, though both GA and FLC are well-known powerful techniques. The graphical interface, developed in Microsoft Visual C#. NET platform, has a flexible and functional structure. By changing motor operating conditions as well as GA and controller parameters, useful practices can be done on the whole system under various situations without wasting time. An evaluation of the tool is given based on student feedback.

CuZn30 sac malzemenin kesme işlemlerinde kesme boşluğu etkilerinin sinir ağı ile modellenmesi - karşılaştırmalı bir çalışma

Clearance effects on the product quality and blanking force in sheet metal blanking process are initially investigated experimentally, and then modelled through neural network (NN) approach. Using eleven different clearances from 8% to 18% with a sampling rate of 1%, blanking processes are applied to sheet material CuZn30 with a thickness of 1mm using a modular template. During the experiments, blanking force, smooth sheared/fractured rate and burr height for the resulting products are measured for each of clearance value and a certain portion of them are taken as example patterns to train the developed feedforward NN. Several NN-based estimation results are presented which verify that a satisfactory neural network model is attained for the concerned parameter estimations. Moreover, comparisons with a recent study that benefits from fuzzy logic as an estimator tool are also presented for the same system. We realize that estimating performance is improved using the NN and a significant contribution of our proposal is that its design is much simpler than that of its counterpart which requires proper and sufficient expert knowledge for tuning of characteristic parameters such as numbers and shapes of membership functions, linguistic control rules.

A new fuzzy logic estimator for reduction of commutation current pulsation in brushless DC motor drives with three-phase excitation

Under the operation of brushless DC motor with three-phase excitation, commutation current pulsation is produced at each commutation at high-speed region. As it can be eliminated when the current slew rates are made equal, a simple and effective fuzzy logic estimator (FLE) is presented first time in the literature to reduce such current pulsation. Its function is to simply regulate the commutation angle accurately to maintain the same current slew rates of commutated phases during commutation, thereby keeping the other phase current unchanged. Unlike previous studies, the presented method does not require torque observer or detection circuits for sensing commutation interval, in addition to commutation time calculation. A genetic algorithm is employed for optimal definition of the FLE’s rule base. The presented method is tested by the accurate simulation, and it is proved that the proposed method is quite capable of reducing the commutation current pulsation and improving the motor output power.

Constant voltage constant frequency control for single phase three level inverter

This paper proposed a single-phase three-level inverter that has constant voltage constant frequency (CVCF) operation system. Harmonic analyses with linear and nonlinear loads have been realized to measure the robustness of the proposed technique. It has been shown that the proposed technique has 15% less harmonic distortion and better performance than the conventional inverter for the same load and switching frequency. The constant voltage and frequency used feedback PI control blocks. The system stability was analyzed with the help of Bode curves. The proposed control schema is verified by MATLAB/Simulink results and the results prove that the proposed method is able to achieve not only low harmonic distortion but constant voltage and constant frequency for various operating conditions.