Hanifi Guldemir

Online modulation recognition of analog communication signals using neural network

In this paper, a neural network based online analog modulation recognition of communication signals is presented. The proposed system can discriminate between amplitude modulation (AM), frequency modulation (FM), double sideband (DSB), upper sideband (USB), lower sideband (LSB) and continuous wave (CW) modulations. A matlab graphical user interface (GUI) is designed to see the intercepted signal, its power spectral density, frequency and modulation type on the screen of the personnel computer. To achieve correct classification, extensive simulations have been done for training the neural network. Theoretical simulations and experimental results indicate good performance even at signal-to-noise ratios as low as 5dB.

Design and implementation of an integrated environment for real‐time control of power electronic systems

In this article, an integrated lab environment for the electrical engineering education is presented which includes hardware and software for the modeling, simulation and control of multilevel inverters. A five‐level cascade inverter is designed and implemented which is an educational platform for the students to test different pulse width modulation (PWM) techniques and verify simulation results. The integrated environment is based on Matlab together with dSPACE. Sinusoidal PWM (SPWM) and Selected Harmonic Elimination PWM (SHEPWM) blocks are constructed in Matlab/Simulink and converted to C code using Matlab/Real‐Time Workshop. C codes are sent to dSPACEs DS1103 digital signal processor (DSP) via dSPACE/Real‐Time Interface software. Voltages with variable frequency and amplitude obtained from SPWM and SHEPWM techniques are applied to an induction motor. Simulation and experimental results are visualized on the designed graphical user interface (GUI). The GUI is developed using dSPACEs ControlDesk software.

The Effect of Rotor Design on Rotor Slot Harmonics in Induction Machines

This paper looks at the effect of different rotor designs on rotor slot harmonics (RSH) in induction-motor, line-current, spectra. The magnitude and the frequency of the rotor slotting harmonics for a number of different rotor designs have been obtained experimentally to identify which of the motor design parameters have significant effect on these harmonics. A computational model has also been developed using the mmf-permeance technique incorporating the effect of saturation, skew, slot-openings, static eccentricity, and the number of rotor slots on these harmonics. The model has been validated using the experimental data. This enables the effect of rotor design changes to be investigated over a wider range of variation than is possible experimentally. The model also facilitates an understanding of the reasons why design changes have the effect they have.

Fuzzy logic based harmonic elimination in single phase inverters

A fuzzy system for the elimination of specific low order harmonics in the output voltage of single phase inverters is proposed. The proposed system does not need look up tables which require much memory as in traditional methods and no need for training which takes much time as in neural networks. Here, modulation index is used as input to fuzzy system and switching signals are generated. Predetermined low order harmonics are successfully eliminated.

Asenkron Motorun Kayma Mod Algılayıcısız Hız Kontrolü

Elektrik suruculerinin hiz ve konum kontrolu gerektiren endustriyel uygulamalarinda, surucu duzeneginin istenilen referans degere cok hizli ve dogru bir sekilde ulasmasi dinamik performans acisindan oldukca onemlidir. Elektrik suruculerinin konum ve hiz kontrolleri yaygin olarak dogrusal kontrol yontemlerinden biri kullanilarak gerceklestirilmektedir. Ancak, sistemin matematiksel modeli cikarilirken yapilan ihmaller, dogrusal olmayan matematiksel modelin dogrusallastirilmasi, bozucu girisler ve sistemin modellenemeyen dinamikleri surucu sistemlerinin performansini etkilemektedir. Ayrica, elektrik makinelerinin manyetik zaman sabitinin cok buyuk olmasi yuk momentindeki degismelerin makinedeki manyetik alani etkilememesini gerekli kilmaktadir. Bu calismada, hiz geri besleme bilgisi olmadan gozetleyici tabanli bir asenkron motorun algilayicisiz hiz kontrolu gerceklestirilmistir. Hiz gozetleyicisinde kayma mod kontrolor kullanilmistir. Kayma mod kontrol ozellikle dogrusal olmayan sistemlere uygulanmaktadir ve bu kontrol yontemindeki temel amac, hatayi anahtarlama yuzeyi veya kayma yuzeyine itmek ve bu yuzeyde tutmaktir. Bu durumda sistem kayma modundadir ve dis bozuculardan veya modelleme hatalarindan etkilenmez. Bu amacla, asenkron motor, yuk, kaynak ve kontrolor iceren surucu sisteminin Matlab/Simulink’te benzetim modeli olusturulmus ve bu benzetim modelinden elde edilen bazi sonuclar verilmistir.