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A 240 Watt output power SEPIC converter with an output voltage of 24 V is proposed to be used in automotive and railway LED applications. The input voltage of the converter varies between 16 V and 36 V. The stability of the converter is guaranteed by moving one of the dominant pole to lower frequency and canceling the other pole with a zero. The phase margin is higher than 560 across all input voltage values. The transients of the switch is damped using a passive snubber circuit. Electromagnetic analyses are performed using Ansys SiWave (TM) to determine voltage drop, current distribution, near and far field and resonance behavior of SEPIC converter. Measurement results indicate that the SEPIC converter is stable under various operating conditions.

The main ideas of this paper are that only some from more than 10 MATLAB Adaptive Methods library may be useful and can be recommended to filter out High-Noises in similar Control Telemetry Channels of Electric Power Components like ESP Systems: only four of applied have shown successfully good results in the early prediction of the ESP motor real insulation disruption (like Signerror, Sign-data and Sign-sign filters). The best among the ten analyzed adaptive filter algorithms was recognized to be, The Normalized LMS FIR filter algorithm — adaptfilt.nlms. Основная идея этой работы заключается в выборе наиболее эффективных адаптивных методов фильтрации сигналов, которые реализованы в MATLAB (из числа более десяти). Сигналы характеризуются высоким содержанием шумов, поскольку они передаются по каналам электропитания погружных электронасосов ПЭД. Исследования показали эффективность применения четырех библиотек адаптивных методов при решении задач прогнозирования состояния изоляции двигателя с целью предотвращения возможных разрушений. Наиболее эффективным адаптивным алгоритмом фильтрации для рассматриваемых задач является Normalized LMS FIR filter algorithm — adaptfilt.nlms.

Background and purposeRisk factors for IS in young adults differ between genders and evolve with age, but data on the age- and gender-specific differences by stroke etiology are scare. These features were compared based on individual patient data from 15 European stroke centers. MethodsStroke etiology was reported in detail for 3331 patients aged 15-49years with first-ever IS according to Trial of Org in Acute Stroke Treatment (TOAST) criteria: large-artery atherosclerosis (LAA), cardioembolism (CE), small-vessel occlusion (SVO), other determined etiology, or undetermined etiology. CE was categorized into low- and high-risk sources. Other determined group was divided into dissection and other non-dissection causes. Comparisons were done using logistic regression, adjusting for age, gender, and center heterogeneity. ResultsEtiology remained undetermined in 39.6%. Other determined etiology was found in 21.6%, CE in 17.3%, SVO in 12.2%, and LAA in 9.3%. Other determined etiology was more common in females and younger patients, with cervical artery dissection being the single most common etiology (12.8%). CE was more common in younger patients. Within CE, the most frequent high-risk sources were atrial fibrillation/flutter (15.1%) and cardiomyopathy (11.5%). LAA, high-risk sources of CE, and SVO were more common in males. LAA and SVO showed an increasing frequency with age. No significant etiologic distribution differences were found amongst southern, central, or northern Europe. ConclusionsThe etiology of IS in young adults has clear gender-specific patterns that change with age. A notable portion of these patients remains without an evident stroke mechanism according to TOAST criteria. Click here for the corresponding questions to this CME article.

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009, Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2009, Bu çalışmada, elektrokimyasal empedans spektroskopi yöntemi ile li-iyon polimer pillerin hücre kinetik parametreleri elde edilmiş ve hücrelerin zorlanmış dolma ve boşalma durumlarında bu parametrelerin değişimi kuramsal olarak incelenmiştir. Li-iyon polimer pillerde oluşabilecek yanlış doldurma ve boşaltma işlemleri sebebi ile meydana gelen geri döndürülemez etkilerin klasik hücre modelleri tarafından tam olarak yansıtılamadığı görülmüştür. Bu nedenle çalışmada hücre eşdeğer devre modeli arıza durumlarına göre geliştirilmiş ve sınıflandırılmış, yeni geliştirilmiş hücre eşdeğer devresi modeli ile pil sağlamlık durumunun daha iyi yansıtılacağı önerilmiştir. Normal dolma ve boşalma durumlarında yapılan deneysel çalışma ile klasik pil modelinin sağlamlık durumunun değerlendirmesi için yeterli olduğu ve klasik modelin sağlıklı bir biçimde durumu yansıttığı görülmüştür. Deneysel çalışmalar ile, çeşitli arıza durumlarını meydana getirerek inceleme gerçekleştirilebilmesi için bir dizi hücre testi planlanmıştır. Aşırı dolma ve boşalma durumlarının ve etkilerinin incelendiği bu deneysel çalışmalar neticesinde klasik modelin durum değerlendirme için yetersiz kaldığı ispat edilmiş ve bu çalışmada önerilen modelin arıza durumlarını daha gerçekçi biçimde yansıttığı görülmüştür. Bu çalışmada eşdeğer devreye seri olarak yeni bir direncin, paralel kolda bulunan kapasiteye ek olarak, seri ve paralel kapasitelerin yine paralel kolda bulunan dirence ilave seri ve paralel dirençlerin eklenmesinin ile devrenin arıza tanısı ve sağlamlık durumunu daha iyi yansıtacağı önerilmiştir. Elde edilen deneysel sonuçlar ile bulanık mantık tabanlı yeni bir sağlamlık değerlendirme yöntemi oluşturulmuştur. Bu yöntem ile pillerin geçmişte karşılaştıkları geri döndürülemez etkiler irdelenebilmekte, böylece bu olumsuzlukların pil ömrüne ne ölçüde etki etmekte olduğu değerlendirilebilmektedir. Bu yeni sağlamlık değerlendirme yöntemi ile li-iyon polimer bir pilin sağlamlık durumunu yansıtan yeni bir MATLAB Simulink modeli geliştirilmiştir., In this study, li-ion polymer cell kinetic parameters were obtained by electrochemical impedance spectroscopy method and changes in these parameters were analyzed theoretically in cases of forced charging and discharging. It was seen that, classical cell models were not sufficent enough to mirror the irreversible effects on li-ion polymer cells caused by improper charging and discharging procedures. Therefore cell equivalent circuit was improved and classified according to the failure states and it is suggested that the improved model is better to reflect the cell state of health. Experimental studies denote that classical cell model is sufficient and classical method is proper for state of health determination under normal charging and discharging cases. In order to realise a detailed inspection on different fault states series of cell tests were planned and realised by experimental studies. The aim of these cell tests was to obtain the parametric differences according to normal operation, overdischarge and overcharge conditions. It was proved by experiments concentrated on overcharge and overdischarge characteristics that classical cell model is not sufficient and suggested new model is more realistic for state of health determination. Forcing effects were classified while unproper charging and discharging conditions for Li-ion polymer cells and it was seen that the classical model is not sufficient to explain in detail the parametric changes in equivalent circuit. It is proposed that addition of a serial resistance, a serial and parallel resistance to the first parallel branch and a serial and parallel capacitor for the second parallel branch in equivalent circuit is much more sufficient to reflect the state of health and fault detection. A new fuzzy logic based state of health evaluation method was formed from experimental results. This method yield to define the irreversible changes that cells encounter in their history and analyse their effect to cell life. A new MATLAB Simulink model using this new state of health evaluation method for li-ion polymer cells was developed., Doktora, PhD

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005, Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2005, Bu tez çalışması, dalgacık teorisi yardımıyla fırçasız doğru akım motorunun (FDAM) algılayıcısız kontrolüne ilişkin yeni bir yöntemin geliştirilmesini amaçlamaktadır. Konum algılanması amacıyla iki yöntem benimsenmiştir. Bu yöntemlerden ilkinde sonlu elemanlar metodu (SEY) kullanılarak faz sargılarının öz endüktansları hesaplanmıştır. İkinci yöntemde ise sargılarda endüklenen gerilimlerin sıfır geçiş noktalarının öngörüsünün hesaplanması hedeflenmiştir. Kalkış problemi, ilk yöntemde faz öz endüktansları fonksiyonu L=L () yardımıyla, ikinci yöntemde ise her dönüş yönü için hazırlanmış, belirli bir eğimle artan frekans profiline bağlı olarak oluşturulan tablo yardımıyla sağlanmıştır. İlk olarak FDAM’nin Hall Effect algılayıcılarla çalıştırılması gerçekleştirilmiştir. Fırçasız DA motorunun MATLAB/Simulink ortamında modeli kurulmuş ve benzetişim performansları elde edilmiştir. PID ve Bulanık lojik kontrol algoritmaları geliştirilmiş, akım ve hız kontrolü gerçekleştirilerek performans sonuçlarına ulaşılmıştır. Daha sonra FDAM’nin PWM darbeleri, deneysel olarak dSPACE dijital işaret işleme hızlı kontrol prototipleme kitindeki DS2201 çoklu I/O kartı ve DS1005 işlemci kartının kullanımıyla üretilmiştir. Zaman domenindeki faz akımlarının ve endüklenen gerilimlerin dalga şekilleri kaydedilmiştir. Deneysel ve benzetişim sonucu elde edilen dalga şekillerine Daubechies dalgacık tipli ayrık dalgacık analizinin uygulanması ile algılayıcısız kontrol için önemli olan komutasyon aralıkları belirlenmiştir. Böylece herhangi bir pozisyon algılayıcı kullanılmaksızın komutasyon anlarını öngören algoritma geliştirilmiştir. Bu prosedür deneysel olarak uygulanmış ve önerilen metodun FDAM’nin algılayıcısız kontrolünde faydalı olduğu başarılı bir şekilde gösterilmiştir. Aynı zamanda benzetişim modeli ve bu modelin dalgacık analizi sonuçlarının deneysel çalışmalarla büyük bir uyum içinde olduğu görülmüştür., This thesis tackles to develop a novel sensorless drive technique for brushless DC motors (BLDC) by using wavelet theory. Study adopts two methods of position prediction. The first method involves self phase inductance variation of which finite element method (FEM) analysis is employed. The second method is based upon the induced voltage (back EMF) and zero crossing point estimation. Starting problem is solved by using L=L (Ө) position inductance function for the first method and by providing a look-up table for each direction of rotation for the second method. Initially a BLDC motor with Hall Effect sensors is handled. The MATLAB/Simulink model of the motor is established and the simulation performances are obtained. A PID and a fuzzy control algorithms are developed, current and speed controlled performance predictions are obtained. Then as an experimental study, BLDC motor’s PWM pulses are produced by DS1005 processor board and DS2201 multi I/O board of dSPACE digital signal processing (DSP) rapid control prototyping kit. The time domain input phase currents and induced voltage waveforms are recorded. The Daubechies discrete wavelet analyses of the experimental and simulation waveforms are obtained with an extra emphasis on commutation intervals. So an algorithm is developed to predict the commutation instants without any position sensor. This procedure is applied experimentally and it is successfully demonstrated that the proposed method described above could be useful for sensorless control of brushless DC motors. It is also shown that, results of the simulation model and its wavelet analysis are in a very good agreement with those of experiments., Doktora, PhD

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005, Rüzgar gücü, tüm dünyada ve özellikle Avrupa’da enerji üretimi açısından giderek yaygınlaşmaktadır. Geçen yıllarla beraber gelişen teknolojiler ve azalan maliyetler sonucunda artık MW mertebesinde rüzgar türbinlerinin kullanımı artmaktadır. Bu yaygın kullanımın sonucunda enerji üretimi, merkezi olmaktan uzaklaşıp dağınık bir enerji üretim şekline bürünmektedir. Bu çalışmada, büyük güçlü rüzgar türbinlerinin, özellikle daimi mıknatıslı senkron generatörlerin kullanıldığı doğrudan tahrikli rüzgar türbinlerinin, yapısı ve şebekeye olan etkileri araştırılmış ve bu etkilerin azaltılması için kullanılan yöntemler incelenmiştir. Ayrıca şebekeye olan bağlantı uzaklığı ve şebeke kısa devre kesme gücü değişimlerinin etkileri araştırılmıştır. Yapılan bilgisayar benzetimleri ile rüzgar hızının değişimi sonucunda, yük akım harmoniklerinde meydana gelen değişimler incelenmiş, rüzgar hızının artması veya azalması durumunda yük akım harmoniklerinin arttığı görülmüştür., Wind power is getting popular for energy generation in the world, especially in Europe. In the recent years, with the new technologies and decreasing prices, the use of MW range wind turbines is increasing. With this increase in usage of wind power systems, the power generation is becoming more decentralised. In this study, the structure of large power wind turbines, especially directly driven wind turbines using permanent magnet synchronous generators, and the effects on the electrical power network are studied, and the solutions to decrease these effects are analysed. Also the effects of modification of the distance between point of common coupling and the wind power system and modification of short-circuit power of the power network are studied. With computer simulations, the effect of the wind speed on the load current harmonics are studied and it is shown that with the change in wind speed, the current harmonics are increased., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005, Bu çalışmada, seri-paralel konfigürasyona sahip bir hibrit elektrikli araç incelenmiş, hibrit elektrikli araclara yönelik teknik bilgiler özetlenmiş, seri paralel hibrit elektrikli aracın Matlab/SIMULINK programında modellenmesi yapılmış, oluşturulan model yardımıyla aracın çalışması şehir içi ve şehir dışı sürüş çevrimleri için simüle edilmiş, aracın çalışma algoritması bu çevrimler için optimize edilmiştir. Aracın modellenen bileşenleri; aracın içten yanmalı motoru, aracı hareket ettiren elektrik makinası, hareket miline planet dişli sistemiyle bağlanmış ana baraya seri bağlı generatör, planet dişli sistemi, aracın makanik ve dinamik sistemi, akü ve konvertörler ile aracın hareket algoritmasını içeren kontrol ünitesidir. Şehir içi ve şehir dışı yol çevrimleri için standart kabul edilen çevrimler kullanılmıştır. Sonuçta, bileşenleri esnek bir şekilde çeşitli uygulamalar için değiştirilebilen ve geliştirilebilecek özel çevrimler için de tekrar optimize edilebilecek bir model kurulmuş, ileride hibrit elektrikli araç konusunda yapılacak çalışmalara fayda sağlabileceği gözlemlenmiştir., In this thesis, a hybrid electrical vehicle with series-paralel configuration is investigated, technical information on hybrid electrical vehicles is summarized, modeling of a series parallel hybrid electrical vehicle is realized on Matlab/SIMULINK program, vehicle operation on city and highway driving cycles are simulated with the help of this model and the operation algortihm of the vehicle is optimized. The modelled components are; internal combustion engine of the vehicle, the driving electrical machine, a generator serially connected to main bus and mechanically connected to main shaft by planetary gears, mechanical and dynamic system, battery and convertors and also the control unit including the motion control algorithm of the vehicle. As a result, a model, with flexible componets those can be updated for various applications and also can be re-optimized for special driving cycles, is built and it is seen that this model can be used in future works on hybrid electrical vehicle., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2003, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2003, Günümüzde prototip ve tasarım çalışmaları, maliyetlerin düşürülmesi ve tasarımın optimizasyonu hedeflenerek, matematiksel modelleme ve simülasyon yazılımları ile desteklenmektedir. Hibrid elektrikli araçlarda güç sisteminin kurulması, farklı kaynaklar arasında yük paylaşımına yönelik güç yönetim stratejilerinin belirlenmesi ve tasarımın optimizasyonu gibi konuların matematiksel yazılımlar ile incelenmesi önem taşımaktadır. Bu tez kapsamında öncelikle elektrik ve hibrid elektrikli araç kavramları tanımlanmış ve elektrikli araçlarda kullanılan alt sistemler incelenmiştir. Seri hibrid konfigürasyona sahip bir araca yönelik tasarım çalışmaları yürütülmüş, alt sistemlerin modelleri geliştirilmiş ve çeşitli sürüş çevrimlerinde simülasyonu yapılmıştır. Son olarak daha önce prototipi geliştirilmiş olan bir elektrikli araca yönelik performans simülasyonları yapılmış ve sonuçları deneysel sonuçlar ile karşılaştırılmıştır., To be able to decrease prototyping costs and optimize the design, today’s research and development projects are supported by mathematical modeling and simulations software. Power system architecture design, determination of power flow management strategies and optimization of the design by mathematical software are very important. In the scope of this thesis, first electric and hybrid electric vehicle concepts have been introduced and subsystems have been investigated. Design studies for a series hybrid electric vehicle have been conducted, subsystem models have been developed and under different driving cycles, the vehicle has been simulated. Finally performance simulations of a vehicle have been done and results have been compared with experimental results., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2001, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2001, Bu çalışmada rezonans çeviriciler genel olarak incelenmiş, farklı rezonans çeviricilerindeki rezonans devre anahtarlarının sıfır akım ve sıfır gerilimde tetiklenerek anahtarlama kayıplarının sıfıra indirildiği gösterilmiştir. Farklı birçok rezonans çeviricisi üzerine yapılan benzetim çalışmaları sonunda, gerilim kilitlemeli tip seri yüklemeli seri rezonans çeviricisi geliştirilmeye değer bulunmuştur. Bu amaçla yapılan spice benzetimleri ile çeviricinin bilgisayar ortamında incelenmesi sağlanmış, daha sonra bu çevirici teknolojisini kullanarak yapılan iki adet prototip ile benzetiminin ve performansının uyum içerisinde olduğu gösterilmiştir., In this study, resonant converters and their behaviours are examined. It’s shown that the switching losses are zero by switching at zero current and zero voltage in different resonant topologies. After analysing of different resonant converter topologies, capacitive voltage clamp type, series loaded series resonant converters are examined detailed. By using spice simulations, the converter is analysed and by using this resonant technology, two prototype has been designed. It’s shown that there is a good agreement between the spice simulation and experimental curves., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2001, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2001, Bu çalışmada, enerjinin ülkelerin gelişme sürecindeki önemi doğrultusunda, Dünyadaki durum dikkate alınarak, Türkiye’nin enerji politikası ortaya konmuş, günümüze kadarki gelişmeler ve projeksiyonlara bakıldığında beklenen gelişmeler göz önünde bulundurularak öneriler geliştirilmiştir. Bu amaçla, coğrafya, nüfus, endüstri, ekonomi gibi faktörlerin enerji politikasına etkisine yer verilerek, günümüze kadarki birincil enerji üretim, tüketimleri ve yirmi yıl içindeki üretim, tüketim projeksiyonları ele alınmıştır. Türkiye’nin genel enerji talebi, simülasyona dayalı olan MAED (model for analysis of energy demand) modeli yardımıyla belirlenmiştir. Bu incelemeler sonucunda Türkiye’nin genel enerji politikası, birincil enerji kaynakları, ikincil enerji kaynakları ve yenilenebilir enerji kaynakları üzerine öneriler verilmiştir. Sonuçlara bakıldığında, Türkiye’nin enerji politikasının gelişiminde bir enerji üzerinde yoğunlaşmak yerine enerji çeşitliliği üzerine gitmek önem kazanmaktadır., In this study, through the importance of the energy in developing time period of the countries, considering the situation in the world, energy policy of Turkey is put forth, suggestions are improved by considering the developings up today and considering developings expected when looking at the projections. Targeting this goal, putting forth the effects of the factors like geography, population, industry, economics on energy policy; primary energy production, consumption up today and production, consumption projections in twenty years are examined. Turkey’s general energy demand is made clear by the help of MAED (model for analysis of energy demand) model, which is based on simulation. After these examinations, suggestions on Turkey’s general energy policy, primary energy supplies, secondary energy supplies and renewable energy supplies are given. Taking results under consideration, for developing of Turkey’s energy policy, instead of concentrating on one energy kind, variety of energy takes importance., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2000, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2000, Bu tez de endüstriyel uygulamalarda geniş bir uygulama sahası bulan bulanık mantık kontrolörler incelenmiş ve bulanık mantık, bir saç kesme sürecine uygulanmıştır. Sac kesme süreçleri genelde programlanabilir lojik kontrolörlerle(PLC) kontrol edilirler. Bu çalışmada, sürece alternatif bir bulanık mantık kontrol metodu geliştiridi ve uygulandı. Bu tezde sac kesme sisteminin çalışması özellikleri açıklandı. Sacın oluşturduğu sehimi tanımlamada dört adet dijital algılayıcı yerine bir adet ultrasonik algılayıcı kullanıldı. Yeni sistemin benzetişimi MATLAB-SIMULINK programı kullanılarak yapıldı. Bulanık mantık modeli sisteme uygulandı. Bu model kullanılarak bulanık mantık performansı hesaplandı. Benzetişim modeli ile bulanık mantık konrtrolörlerin daha iyi performans karakteristiklerine sahip olduğu gösterildi. Yeni sistemin parametre değişimlerine ve ani kötü etkilere daha az duyarlı olduğu görülür. Sac kesme süreci kontrolü yüksek çalışma hızlarında çalışabilmiştir., In this thesis a fuzzy logic and fuzzy logic controllers are studied and, their applications on a strip-steel rolling and cutting process is investigated. Generally strip-steel cutting process is controlled by programmable logic controllers (PLC). In this study, a fuzzy logic control method is developed and proposed as an alternative to this process. This thesis commences with the presentation of the properties of strip-steel cutting process. Instead of four digital sensors, an ultrasonic sensor is used for defining the catanery. The simulation of the new system is achieved by using MATLAB-SIMULINK program. Fuzzy logic model is inserted in to the system model. The fuzzy control performance is computed by using the model described above. It is shown on simulation model that, fuzzy logic controller provides better performance characteristics. The new system is less sensitive to the parameter variations and disturbances. It is also capable to control the cutting process in higher speeds, which means higher productivity., Yüksek Lisans, M.Sc.

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2000, Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2000, Bu çalışmada, özel bir tür elektrik motorunun tasarımı, imalatı, deneyleri ve denetimi yapılmıştır. Motor, sürekli mıknatıslı ve demir çekirdeksiz olarak tasarlanmıştır. Endüvi sargıları baskılı devre tekniğiyle yapılmış yüzeysel sargılardır. Yüksek enerjili NdFeB mıknatısların ve yüksek akım yoğunluklu yüzeysel sargıların kullanılmasıyla, motor büyük kuvvetler üretebilmektedir. Bu nedenle, doğrudan sürüş uygulamalarına uygun bir motordur. Çalışmada, bir deney motorunun yapımı gerçekleştirilmiş ve deneysel değerler elde edilmiştir. Deneysel değerlerle, kuramsal değerlerin birbirine çok uygun olduğu gözlenmiştir. Bilgisayar ortamında motorun modeli oluşturulmuş, çeşitli çalışma durumları için benzetim sonuçları elde edilmiştir. Motor modelinde, mıknatısların, yapısal, yüklenme ve sıcaklık demagnetizasyon etkileri dikkate alınmıştır. Motorun denetim düzeneği, bilgisayar yazılımı, DSP kartı, güç elektroniği devresi ve doğrusal kodlayıcıdan oluşmaktadır. Denetim devresi, modelle, gerçek dünya arasında DSP kartı aracılığıyla bilgi alışverişi yapan bir “döngüde donanım” (hardware-in-the-loop) düzeneğidir., This study deals with the design, analysis and experiments of a permanent- magnet linear brushless d.c. machine with printed circuit armature. Since armature has no magnetic core, this motor is also called as coreless motor. The designed motor has double sided permanent magnet field circuit and an armature between these magnets. This motor is also called axial flux or sandwich type of linear machine. In order to obtain field distribution, field solutions are evaluated. The effect of parameters of permanent magnet, gap length, armature magnetomotor force (m.m.f.) and temperature are taken into account. The thrust force, input power and other relevant performance values are measured and compared with those of simulations. It is seen that, there is a good agreement between experimental and theoretical values. Since this system is considered as an HIL (hardware-in-the-loop) control application, the modelling and simulation have a very important impact on this study. The demagnetization characteristic of the permanent magnets and the definition of operation point is obtained by taking temperature rise and various loading conditions into account. In direct drive applications, wide range of loading is required, so the loading and temperature demagnetization effects of the NdFeB magnets have crucial importance in modelling of the motor., Doktora, PhD

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2000, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2000, Bu tez de endüstriyel uygulamalarda geniş bir uygulama sahası bulan bulanık mantık kontrolörler incelenmiş ve bulanık mantık, bir saç kesme sürecine uygulanmıştır. Sac kesme süreçleri genelde programlanabilir lojik kontrolörlerle(PLC) kontrol edilirler. Bu çalışmada, sürece alternatif bir bulanık mantık kontrol metodu geliştiridi ve uygulandı. Bu tezde sac kesme sisteminin çalışması özellikleri açıklandı. Sacın oluşturduğu sehimi tanımlamada dört adet dijital algılayıcı yerine bir adet ultrasonik algılayıcı kullanıldı. Yeni sistemin benzetişimi MATLAB-SIMULINK programı kullanılarak yapıldı. Bulanık mantık modeli sisteme uygulandı. Bu model kullanılarak bulanık mantık performansı hesaplandı. Benzetişim modeli ile bulanık mantık konrtrolörlerin daha iyi performans karakteristiklerine sahip olduğu gösterildi. Yeni sistemin parametre değişimlerine ve ani kötü etkilere daha az duyarlı olduğu görülür. Sac kesme süreci kontrolü yüksek çalışma hızlarında çalışabilmiştir., In this thesis a fuzzy logic and fuzzy logic controllers are studied and, their applications on a strip-steel rolling and cutting process is investigated. Generally strip-steel cutting process is controlled by programmable logic controllers (PLC). In this study, a fuzzy logic control method is developed and proposed as an alternative to this process. This thesis commences with the presentation of the properties of strip-steel cutting process. Instead of four digital sensors, an ultrasonic sensor is used for defining the catanery. The simulation of the new system is achieved by using MATLAB-SIMULINK program. Fuzzy logic model is inserted in to the system model. The fuzzy control performance is computed by using the model described above. It is shown on simulation model that, fuzzy logic controller provides better performance characteristics. The new system is less sensitive to the parameter variations and disturbances. It is also capable to control the cutting process in higher speeds, which means higher productivity., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1999, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1999, Bu çalışmada, öncelikli olarak üniversal motorun yapısı, çalışma prensibi ve eşdeğer devre modeli verilerek, matematik model geliştirilmiştir. Bu matematik model Simulink paket programında kullanılarak üniversal motor benzetişim yazılımı oluşturulmuştur. Geliştirilen yazılım UMSIM olarak isimlendirilmiştir. Çeşitli üniversal motorlara endüktans deneyleri, yük performans deneyleri, boşta çalışma ve yavaşlama deneylere uygulanarak, bu motorlara ilişkin eşdeğer devre parametreleri ve kayıplar belirlenmiştir. Deneyler sonucu elde edilen parametreler UMSIM yazılımında kullanılarak bu motorların gerçekleştirilerek, performans değerleri elde edilmiştir. Ayrıca, hassas performans ölçümü yapan Magtrol test düzeneği yardımıyla performans değerleri deneysel olarak da elde edilmiştir. Öyleki bulunan bu performans değerleri bilgisayar benzetişimiyle bulunan sonuçlar ile karşılaştırılmış olup, sonuçların birbirlerini desteklemekte olduğu görülmüştür. Bu durum oluşturulan benzetişim algoritmasının doğruluğunu göstermektedir. Çalışmada son olarak, üniversal motor tasarım metodolojisi geliştirilmiştir. Tasarım yöntemi ve tasarım sırasında kullanılan denklemler, grafikler ve tablolar elde edilmiştir. Tasarım gerçekleştirilmesinde görsellik ve kullanım kolaylığı öncelikli olarak düşünüldüğünden, görsel bir programlama dili olan Visual Basic yardımı ile tasarım metodolojisi bir yazılım haline getirilmiştir., This study commences with the development of the operational priciples and mathematical model of universal motors. The mathematical model is used on Simulink package programme thus the simulation of universal motor is realized. This programme is called UMSIM. The equivalent circuit parameters and losses of the universal motors are obtained by conducting various inductance tests, load performance tests, no load free running tests and slowdown tests. These parameters are employed in UMSIM simulation programme and the performance values are computed. In addition the experimental performance values are recorded by the use of the high quality Magtrol set-up. The experimental and computational performance values are compared and it is seen that those results are in good agreement. This yields that, the developed simulation programme (UMSIM) is adequate for performance prediction. As a last past of this work, a design methodology is studied for universal motors. The design method and equations, graphs, tables are developed. Since the main objective is to develop a user friendly visual computer programme, the Visual Basic language is chosen. As a result the design methodology is established in visual computer environment., Yüksek Lisans, M.Sc.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1999, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1999, Bu çalışmada güneş pillerinden beslenen ve şebekeye paralel çalışan sistemler incelenerek karşılaştırılmış ve bu sistemlerden akım aradevreli üç fazlı evirici inceleme konusu olarak seçilmiştir. Sistem güç ve kontrol bloğu tasarımı yapılmış, sistemin problemleri ve karşılaşılabilecek problemler üzerinde durulmuştur. Kontrol sistem simülasyonları MATLAB-Simulink de gerçek zaman simülasyonları ICAP de yapılmıştır. Sistemin gerçeklenmesinde PWM tekniği kullanılarak evrici IGBT kullanılarak oluşturulmuştur. Kontrol devresi anolog olarak oluşturulmuş olup temel olarak PI kontrolörden oluşturulmuştur. Güç katıyla şebeke arasında izolasyon amacıyla ayırıcı bir güç transformatörü kullanılmıştır.Tasarımı yapılan sistemin laboratuvar prototipi yapılarak simülasyon verileri incelenmiştir. Sistem tasarımı uygulama problemlerinin çözülmesini sağlamak nedeniyle revize edilmiştir. Elde edilen test sonuçları ile simülasyon sonuçları karşılaştırılarak sonuçları değerlendirilmiştir., In this study grid connected systems fed by solar cell are compared and one of the systems current fed three phase inverter is chosen as the concept of the study. The power and control stage is designed and some possible problems are considered. The control system simulations are made by MATLAB-Simulink and real time simulations are made by ICAP. In the power stage PWM technique is proposed and IGBT is used in the power stage construction. The control stage is designed with analog circuits and basically forms a typical PI controller. An isolation power transformer is used for separation of grid and the power stage. The prototype of the system designed is produced and simulation results are examined. System design is revised due to the practical system considerations. The test results are compared and evaluated., Yüksek Lisans, M.Sc.

ÖZET Zaman ilerledikçe, teknolojik gelişmelerin ilerleme hızı da artmaktadır. Bununla birlikte insanların her alandaki beklenti ve istekleri kendini yenilemektedir. Bu tez çalışması da rezonans çevirici teknolojisi ile yapılan elektronik cihazların, diğer teknolojilere üstünlüğünü anlatmaktadır. Bölüm 2'de temel seri rezonans ve paralel rezonans devrelerinin açıklamaları, frekans karakteristikleri ve sıfır akım gerilimde anahtarlama teknikleri anlatılarak başlangıç yapılmıştır. Bu bölümde N.Mohan'ın Güç Elektroniği kitabından faydalanılmışım Bunların ışığı altında Bölüm 3'te ise, seri yüklemeli, paralel yüklemeli, seri paralel yüklemdi seri rezonans çeviriciler, bu çeviricilere ait devre şemaları, eşdeğer devreleri ve kalite faktörü, ac analiz ile incelenmiştir. Bu kısımda ise ağırlıklı olarak R.L. Steigenvald'in makalesinden yararlanılmıştır. Bölüm 4'te paralel yüklemeli seri rezonans teknolojisi ile yapılan kesintisiz güç kaynağı, seri yüklemeli seri rezonans teknolojisi ile yapılan kaynak makinası incelenmiştir. Bu cihazların ortak özelliği, yüksek frekanslarda anahtarlama yapılması böylece aynı gücün daha küçük boyutlu pasif malzemelerle ( kondansatör, eııdüktans, trafo vs. ) aklarılabilmesini sağlamasıdır. Böylece daha ekonomik cihazlar yapmakta mümkün olmaktadır. Boyutların küçülmesi, çok daha kolay taşınabilir cihazların yapılmasına olanak tanımıştır. Sıfır akım ve gerilimde anahtarların tetiklenmesiyle, anahtarlama kayıplarının ve EMİ' m çok düşük olması bu teknolojiyi cazip kılmaktadır. Burada ise A. Kadiç'in çalışmalarından faydalamlmıştır. Aynı bölümde KGK'nııı ve kaynak makiııasının enerji allında çalışırken, osiloskop ile ölçülen akım gerilim değerleri ve spice analizi yapılarak elde edilen akım gerilim değerleri gösterilmiştir. Yapılan spice analizlerinde, akım ve gerilim değerleri, en düzgün şeklini alana kadar, pasif malzemelerin değerlerinde ve çalışma frekansında vı ıdeğişiklikler yapılmıştır. Spice analizlerini yapmamızın amacı, böylesine teknolojik ve yoğun bir çalışma gerektiren cihazların tasarımına ışık tutmaktır. Bu çalışmaların sonucunda, spice analizinin katkılarıyla rezonans çeviricili cihazların yukarıda belirtilen şartlarda çalışması için, tasarımlar yapılmış ve diğer teknolojilere göre üstünlükleri ortaya çıkarılmıştır. vm DEVICES WITH RESONANT CONVERTER AND SPICE ANALYSIS SUMMARY As the time goes by, the progress in technology increases. Furthermore in every field people's expectations and wishes increase. This thesis explains the superorily of the electronic devices which are designed by resonant converter technology, to the other devices. In chapter 2, an introduction is made by explaining the main serial and parallel resonant circuits and the techniques of switching in zero cuirent and voltage. In this chapter, there are some informations taken from Power Electronics Book written by NMohan. In chapter 3, the serial loaded, parallel loaded and serial parallel loaded serial resonant converters, the circuit diagrams of these converters, eqivalent circuits and quality factor are examined by using ac analysis. These informations are taken from an article written by R.L. Steigervvald. In chapter 4, the uninlerruptable power supply which is made by parallel loaded serial resonant converter and the welding machine which is made by serial loaded serial resonant converter, is examined. The common property of these devices is switching in the high frequencies and therefore the devices can give same power to the output with smaller size passive components ( condansalor, inductance, transformer etc). So, it becomes possible to make more economical devices. With smaller dimension, the devices become more portable and easy to cary. By switching in the zero current and voltage, the switching losses and EMI become very low' and this makes this technology more attractive. These are from an article written by A. Kadiç. i In the same chapter, the current and volt3ge values of UPS and welding machine which are measured by osciloscope which are obtained by spice analysis are shown. In spice analysis, some changes were made in values and frequencies of components, till the current and voltage values reach the most suitable value. The IXaim of employing spice analysis is helping the planning of these devices which need hard and technological working. In conclusion, in order to make the devices with resonant converter work in the conditions mentioned above, designs are made by the help of spice analysis and their superorities to the other technologies are shown. 89

ÖZET Asenkron motor dinamiği incelenerek, kayan kip kontrol yöntemi için MATLAB ortamında kontrol programı oluşturulmuştur. SIMULINK simülasyon tekniği kullanılarak, kayan kip kontrol yöntemi asenkron motora uygulanmıştır. Simülasyon modelleri ve sonuçları 'Bölüm 6' da verilmiştir. SUMMARY Sliding Mode Control of Induction Machine Equations of motion of the systems are nonlinear due to the complexitiy of the system's dynamics. Various techniques have been suggested for the design of controller. The control theory of variable structure systems (VSC) can be used on the converter and the induction machine together to develop a control strategy that can deal with switching converter and motor nonlinearities. The application of sliding mode control to the induction machine and its simulation results in MATLAB and SIMULINK are presented. Dynamic Model of Induction Machine The dynamic performance of an induction machine is complex because of the coupling effect between the stator and rotor phases, where the coupling coefficients vary with rotor position. Therefore, the machine model can be described by differential equations with time-varying coefficients. The dynamic model of a machine can be expressed in either a stationary or a rotating reference frame. In a stationary frame, the reference a and 3 axes are fixed on the stator, where as in a rotating reference frame these are rotating. The rotating frame may either be be fixed on the rotor or move at synchronous speed. The advantage in a synchronously rotating frame model is that with sinusoidal supply the variables appear as dc quantities in steady-state conditions. XIRotor and stator equations can be given as follows, V9d=R6isd-co8M/8

ÖZET Doğru akım motoruyla hız ve gergi kontrolü başlığı altında, öncelikle serbest uyarmalı doğru akım motorlarının karakteristikleri incelenmiş ve ilgili denklemler verilmiştir. İkinci bölümde tez boyunca incelediğimiz Allen-Bradley marka dijital doğru akım sürücülerinin genel özellikleri, mevcut tipleri ve bu tiplere göre gerek alan devresinde kullanılan tek fazlı tam dalga doğrultuca, gerekse, armatür devrelerinde kullanılan ikili tip çevirici incelenmiş ve ilgili devre şemaları ve denklemler verilmiştir. Üçüncü bölümde tahrik sistemleri ve özel olarak dönme hareketi ile sancı çalışmasıyla ilgili karakteristikler ve denklemler sunulmuştur. Dördüncü bölümde ise. doğru akım sürücüleriyle ilgili genel karakteristiklerin ve eşitliklerin yanısıra kullanım alanları ortaya konmuştur. Beş numaralı bölümde öncelikle armatür kontrollü ve sonrasında alan kontrollü serbest uyarmalı doğru akım motoruyla ilgili lineer matematiksel modeller çıkarılmıştır. Altıncı bölümde, Allen-Bradley marka dijital doğru akım sürücülerinin moment ve proses trim çalışma modlarına göre matematiksel modeller ortaya konmuştur. Burada bazı çalışma modları birbirinin tıpkı olduğundan, tekrardan kaçınmak amacıyla, konu başlığı altında tekrardan sunulmamışlardır. Yedinci bölümde, Allen-Bradley doğru akım sürücülerinin özelliklerinden biri olan parametre kestirimi ve fonksiyon testleri konusuna sadece bir fikir vermesi amacıyla değinilmiş, ayrıntıya girilmemiştir. Sekizinci bölümde ise. bu bölüme deyin gelen anlatılardan istifade ederek, öncelikle hız ve gergi kontrolü yapılan bir proses incelenmiş ve proseste kullanılan, Allen-Bradley PLC ve In-Touch scada proramlanyla ilgili özet bilgi verilmiş, sonrasında prosesin izlenmesi için oluşturulmuş scada sayfaları ve geçmişe yönelik olarak sancı ve sistem ile ilgili bazı analog değerler grafiksel olarak sunulmuştur. Tezin sonuna konan ekde ise, sancı motoruyla ilgili yapılan gözlemler tablo olarak verilip, örnek prosesde yalnızca hız ve gergi kontrolünü gerçekleştiren PLC programı sunulmuştur. xvuı SUMMARY THE SPEED AND TORQUE CONTROL OF DIRECT CURRENT MOTORS The main elements of an electric drive are the controller, converter, motor, mechanical system and the power supply. The essential elements of the mechanical system and power supply are known, but the controller, converter, and motor must be designed or chosen by the designer. However it is important that the mechanical system is clearly specified. When a preliminary design of a desirable drive system has been carried out, it may be discovered that the available electric power supply is inadequate. Therefore, the appropriate kinds of mechanical system and power supplies must be evaluated. Once the speed-torque characteristic demanded by the load has been determined, it is possible to consider which motor-controller combination would be most suitable. This choice would also be influenced by the nature of the available power source. Direct current motors are still a common choice ifa controlled electrical drive operating over a wide speed range is specified. This is due to their excellent operational properties, control characteristics, and economic considerations specified by the over all system design. Allen-Bradley digital dc drives have a field circuit ( single phase full converter ), and an armature circuit ( dual converter ). Single phase fully controlled converter circuit is shown in figure 1. Vac O /N Vdc Figure 1. Single phase fully controlled converter circuit In an inductive load; Vdc = Vdo.cosa 1 The maksimum voltage (Vdo) is obtained when a is zero. Equation I indicates that we can control the mean output voltage by controlling a. We aiso see that when a is greater than 90 the mean output voltage is negative. This facility allows the converter to return energy from the load to the supply, and this is important when we want to use the convener with a dc motor in the regenerating mode. XIXA single full-converter provides unidirectional current at the dc terminals, but the voltage of the dc terminals can be reversed. It is thus capable of providing only two quadrant operation. If two full converters are connected back to back, both the voltage and the current at the dc terminals can reverse, and therefore the system will provide four quadrant operation. Such a system, shown in figure 2, is called a dual converter. İs İs Is + Va Vb Vc İS Is Is SL SL SL Vdi Vd2 SL SL SL Va Vb Vc Figure 2. Dual converter This type coverters have two different operation mode; - Operation with circulating current -Operation without circulating current This system is normally used for high power dc drives, for speed control in both directions. In fact, the dual converter is the static version of the Ward-Leonard motor- generator set. An arrangement for controlling a dc motor with a three phase full wave thyristor converter is shown figure 3. The current iq flowing in the motor and the voltage vq applied to it by the converter in figure 3. When current is flowing in the motor, the following equations holds Lq.(diq/dt) + Rq.iq = Vmsinoat - eq 2 xx»Cvc ast 3&ş ?- TMrlft W` lavcRfw SPEED FEEDBACK SIGNAL Figure 3. Thyristor driven speed regulating system From figure 3 and 4a, average motor current iq and the average thyristor converter output voltage Vd during discontinuous conduction of a motor current given by the following equations iq/(3.Vm/:tX) = (X/R).{ cos[(tt/3) + a] - cos [(7t/3)+a+01] - (eq/Vm).91 } 3 9,- U) (b) Figure 4. Waveforms under both discontinuous and continuous conduction states of current (a) Discontinuous current (b) Continuous current XXIVq/Vm = (3/71). { cos[(tc/3) + a] - cos [(7t/3)+a+ei] - (eq/Vm).91}+(eq/Vm)4 On the other hand, during the continuous conduction of a motor current, the following equations can be derived from figure 3 and 4b iq/(3. Vm/7t.X) = (X/R). [ cosa-(7teq/3. Vm) ] 5 Vq/Vm = (3/7t).cosa 6 The most common arrangement, which is used with only minor variations over almost the whole size range from small drives of say 0.5 kW up to the largest industrial drives of several MW, is the so-called two loop control. This has an inner feedback loop to contrl the current ( and hence torque ) and an outer loop to control speed. Speed Ref. Speed Cont. Encoder Figure 5. Schematic diagram of basic controlled speed drive with current and speed feedback control loops The current loop is to make the actual motor current follow the current reference signal (Iref). It does this by comparing a feedback signal of actual motor current with the current reference signal, amplifying the difference, and using the resulting amplified current error signal to control the firing angle a and hence the output voltage of the converter. Te = Kmiq 7 Torque is directly proportional to armature current ( equation 7 ), so the current controller is in effect also a torque controller. The configuration of a current loop, which includes a nonlinear compensation subloop. during discontinuous conduction is shown figure 6. The loop consist of two control subloops: one searhes for a compensating firing angle Ace which is an given relation to motor current iq and compansates for the nonlinear load characteristics during xxnThis assumes that there is no speed variation effect, because the current response of a dc motor is faster than the speed response. From eq.8, the codition under which the system in figure 7 becomes stable is obtained as follows: Ki

independently. Parallel operation solves the problem from performing operation in different units in the same time. These features makes the computational speed much faster and improves architecture for higher throughput. Accuracy issues is the main part of a processing unit. So to provide better accuracy, the architecture can be designed for avoid numerical errors. The shared memory for both instructions and data and single instruction data bus is significant bottleneck and will cause errors in real time appplications. Architecture, accuracy and speed interact, so an efficient and optimized control solution can only be find with taken care of this issues. The fundemental primitive operation in numerical computation is multiply accumulate step and it is desired to do this in a single clock cycle. DSP can do it with pipelining and parallel operation speed processing by doing more in fewer cycles. The desirable features of a DSP is bus width, expanded arithmetic, data-address generation, instruction sequencing and scaling.To minimize the effect of numerical operations the units must have additional guard bits, bus width must large enough to operate correctly with double precision option. The basic units of DSP system is as follows : Multiplier-accumulator (MAC), Arithmetic logic unit (ALU), Barrel shifter (BS), Data address generator (DAG), Instruction sequencer (SEQ). These units perform rapid execution of arithmetic and logic operations and provides protection against errors with diffirent solutions. All these units can operate in parallel and connect to buses which gives the result in a single cycle. The main disadvantage of DSP is the memory area. For providing speed only limited memory area is put on chip. Thus, large amount of programs can not been stored into memory. There are several differences between microcomputer and DSP systems. Both system has its own advantages and disadvantages. The designer must learn the options of controlled system to make the right decision between DSP and microcomputer. Speed, memory area, software support, peripheral devices and cost will be the main points to select which processor must be chosen. In applications, especially using a sophisticated control algorithm, math operations makes longer the execution time. Microcomputers use look up table to decrease the execution time. But DSP is produced to opareta at this conditions, so it is better to use numerical methods to solve a function. However, there is no enough memory to create look up tables and store program. This is just a sample how DSP and microcomputer solve main problems. Switched reluctance motor (SRM) is one of the alternative motors to asynchronous and DC motors. SRM is a motor which both stator and rotor is salient pole. There is only winding on stator to create flux, no winding IX SUMMARY DSP BASED CONTROL OF SVVITCHED RELUCTANCE MOTOR in recent years, the revolution on the electronics, brings the new devices into the area of control. Opportunities have grown rapidly över past years to solve the problems of control applications. Ali the control systems of a few years were designed by a general purpose microcomputer. But, VLSI design technology brings DSP processor to digital signal processing area with a powerful architectural design. High performance of DSP make it possible to implement a wide range of digital control algorithms for sophisicated applications. A control system is built by a controller and the circuits which provide to connect these parts together. The control system must achieve a desired output to command a process. in the control applications of power electronics and motors, the system is preferred to be a closed loop. The closed loop system takes the reference value and feedback value which came from the sensors and actuators. The controller must compute a desired response from the entire system. The controller can be either analog ör digital. The function is to ensure the system to be stable in ali conditions and respond as quick as possible. Analog controller can be produced with operational amplifiers and passive circuit elements. Analog contollers continiously process a signal and can be used for very high bandvvidth systems. The disadvantages of this controller is hard wired design, suffering from temperature drift and component aging. The system is flexible only for simple design approachs. With the new control algorithms like adaptive ör fuzzy control, it is impossible to design a controller using analog devices. The high performance and reliability of microcomputers put them directly to the control applications. The programmable solution and flexibilty is the main advantages of the digital controller. it is easy to make upgrade and maintain design investment. To control nonlinear systems with sophisticated techniques from modem control algorithm is possible. Digital controller is not affected by enviromental conditions and shows precise behavior. The main problem is that, the processes in nature is analog. So to control these processes with a digital controller, the signals must convert to a kind that both parts understand each other. The digital controller require A/D (analog to digital) and D/A (digital to analog) converters to obtain control of real world data. The accuracy of the viapproximation determines the performance of the digital controller. The conversion betvveen two system can provide by sampling the signal at dicrete time intervals. This limits the bandwidth that can be handled by the controller. There will be always an error because of the loss of information at the conversion cycle. To avoid this error the resolution ör word lentgh of the processor must be increased. Digital controller is built onto a general purpose processor and peripheral devices to make the system flexible for usage in different applications. The choice of the processor is the main problem to determine the behavior of control system. Some tradeoffs have to be made in selecting a processor. The poor performance of digital system is caused by the wrong selection of the processor. in practical area, speed of execution, accuracy and cost determine the choice of processor. Architecture, performance and peripheral integration is the factors which must be considered. Processing signals in real time raises numerical problems, and to ensure the performance of the controller acceptable, they must resolve these numerical problems correctly. The architecture of the processor must provide ali the requirements of the controlled system. Because of the inadequate processor architecture, quantization, truncation, limit cycles and overflow handling errors appear, and several techniques developed to preset these errors. Ûuantization effect is result by representing a signal in discrete time. The analog signals are continious so to compute these signals quantized magnitude levels must be used. The system must support a large word lentgh and scaling shifters to provide the resolution and dynamic range needed. If the gain coefficients and signals are time varying and have large dynamic range, floating point processors must be used. Scaling can be used to minimize the effects of quantization. The arithmetic operations alvvays produce an error because of the finite word length. The processor takes the value, compute the operation and then throw away bits when necessary. Because of the finite amount of storage length, the processor can not produce a result using ali bits, so it made an approach to make the result understandable to computational units. Rounding and truncation is two ways to do this. If the processor compute 16*16 bit multiplication, the result will be 32 bit length. To store and send the result, needs 32 bit bus length and registers. If only 16 bit is avaliable, least meaningfull 16 bits will be thrown away. Truncation will throw away before storage, and rounding will round and then throw away before store the result. Rounding makes the result closerto the real value, so it is better than truncation. There are several ways to minimize the effects of rounding and truncation. Limit cycles can produced from viiquantization and truncation. Insufficent resolution of the output causes to oscillate around the actual value without being able to reach it. The control system can use fractional arithmetic or integer arithmetic. The binary arithmetic is used for represantion of numbers. Two s complement is the better alternate which is used by digital signal processing elements. Fraction numbers is better when the algorithm is multiplication based. If the highest number is 0.99, it is impossible to occur an overflow. But addition calculation can cause overflow. The registers which are effected by overflow, wrap around and change magnitude from most positive to most negative. The processor must take care of with these registers to avoid wrong control behaviour. The saturation mode is provided to prevent the content of registers to wrap around and change signal when an overflow occurs. This is done automaticallly in DSP. The overflow can be avoided with increasing the register size, but it is better solution to put some guard bits to protect the result from overflow. To optimize the dynamic range, data arrays are kept scaled so that the largest value fill all the bits of the data word. Precision and dynamic range of numbers must be balanced to find an optimum solution. The processor must finish processing the signal before the arrival of the next sample or the information will be lost. Also peripheral integration is important from a system cost, ease of design and interface. DSP is the digital signal processor which provide new features to control system applications. DSP is designed by using Harvard architecture, while the microprocessor is designed by Von Neumann architecture. The most important part, the units are independent so can compute same time in parallel. The second main difference is, the memory of data and program is independent from each other so to compute and to execute can be done in single cycle. All functions are performed internally in hard wired logic so that it takes a single cycle to execute most of the mathematical operations. The hardware multiplier can multiply the contents in a single instruction cycle thus the speed is excellent comparing with microprocessors. The multiple bus architecture provides better computing speed performance. High sampling rates can be provided so the precision improve better. DSP gives the real time application flexibility and performance which is predictable, accurate, repeatable and adaptable. Computational speed matched from unit to unit so no bottlenecks develop. To remove bottlenecks pipelining and parallel operation can be used. Bottleneck is a computational delay produced because of the data can not use the buses and units efficiently. In pipelining, the operations broken into subunits and these subunits compute part of operation VIIIindependently. Parallel operation solves the problem from performing operation in different units in the same time. These features makes the computational speed much faster and improves architecture for higher throughput. Accuracy issues is the main part of a processing unit. So to provide better accuracy, the architecture can be designed for avoid numerical errors. The shared memory for both instructions and data and single instruction data bus is significant bottleneck and will cause errors in real time appplications. Architecture, accuracy and speed interact, so an efficient and optimized control solution can only be find with taken care of this issues. The fundemental primitive operation in numerical computation is multiply accumulate step and it is desired to do this in a single clock cycle. DSP can do it with pipelining and parallel operation speed processing by doing more in fewer cycles. The desirable features of a DSP is bus width, expanded arithmetic, data-address generation, instruction sequencing and scaling.To minimize the effect of numerical operations the units must have additional guard bits, bus width must large enough to operate correctly with double precision option. The basic units of DSP system is as follows : Multiplier-accumulator (MAC), Arithmetic logic unit (ALU), Barrel shifter (BS), Data address generator (DAG), Instruction sequencer (SEQ). These units perform rapid execution of arithmetic and logic operations and provides protection against errors with diffirent solutions. All these units can operate in parallel and connect to buses which gives the result in a single cycle. The main disadvantage of DSP is the memory area. For providing speed only limited memory area is put on chip. Thus, large amount of programs can not been stored into memory. There are several differences between microcomputer and DSP systems. Both system has its own advantages and disadvantages. The designer must learn the options of controlled system to make the right decision between DSP and microcomputer. Speed, memory area, software support, peripheral devices and cost will be the main points to select which processor must be chosen. In applications, especially using a sophisticated control algorithm, math operations makes longer the execution time. Microcomputers use look up table to decrease the execution time. But DSP is produced to opareta at this conditions, so it is better to use numerical methods to solve a function. However, there is no enough memory to create look up tables and store program. This is just a sample how DSP and microcomputer solve main problems. Switched reluctance motor (SRM) is one of the alternative motors to asynchronous and DC motors. SRM is a motor which both stator and rotor is salient pole. There is only winding on stator to create flux, no winding IXon rotor. The system must operate normally in closed loop control, with shaft position sensors and encoders. it is necessary to know which stator phase will excited in a time period. The commutation of the phase currents with rotor position must be in synchronize. The motor can be 8/6, 6/4, 12/8 ör another stator rotor pole numbers with different phase numbers. The torque is produced by moving rotor to position where the inductance of excited winding is maximized. The aligned position of motor defined as, stator and rotor poles is aligned exactly, and airgap is minimum. The magnetic reluctance of flux path is in lowest, so inductance is maximum. The control of the phase currents gives the best performance. The requirements of control is to produce smooth torque with minimum ripples, good stability and smooth reversing capability. Different kind of power electronic circuits is defined to take maximum performance. The control of system must be in real time, because torque, current, speed and firing angles reacts as nonlinear function and vary with load conditions. in this thesis, the survey of digital controller design has been made. The microcomputer and DSP systems are introduced by practical point of view, architecture, main units, differences and applications of the systems are explained. The switched reluctance motor control design is explained with power electronic circuit, gate drive circuit and controller circuit realized with microcomputer and DSP, respectively. 121

ÖZET Bu çalışmada rezonans çeviricilerinin anahtar modunda çalışan çeviricilere olan avantajları ve dezavantajları incelenmiştir. Bir güç elektroniği devresindeki güç kaynaklarının boyutlarını küçültmek için reaktif elemanların boyutunu küçültecek çalışma frekansını arttırmak gerekmektedir. Bu esnada yüksek çalışma frekanslarından dolayı ortaya çıkan yüksek anahtarlama kayıplarım da azaltmak gereklidir. Bu amaçla rezonans devreleri kullanılmaktadır. Darbe genişlik modülasyonunu kullanan bütün çeviriciler, her anahtarlama esnasında bütün yük üzerlerindeyken açma veya kapama yapması gereken bir modda çalıştıklarından büyük anahtarlama kayıplarına sebep olurlar. Bu yüzden eğer her anahtarın üzerindeki gerilim veya içinden geçen akım sıfırken o anahtarı iletime veya kesime götürürsek bu anahtarlama kayıplarının üstesinden gelinebilir. Bu çalışmada birinci ve ikinci bölümlerde renosans çeviricilerine niçin gereksinim duyulduğundan ve çeşitlerinden bahsedilmiş olup üçüncü bölümde en basit yapıdaki renosans çeviricileri incelenmiştir. Çalışmanın esas kısmım oluşturan dördüncü bölümünde ise bu tip çeviriciler farklı çalışma frekansları için detaylı olarak incelenmiştir. -v- SUMMARY RESONANT CONVERTERS In this study advantages and disadvantages of resonant converters versus switch-mode converters are discussed.In all the pulse-width-modulated dc-to-dc and dc-to-ac converter topologies, the controllable switches are operated in a switch-mode where they are required to turn on and turn off the entire load current during each switching. In this switch mode operation, the switches are subjected to high switching power loss that increases linearily with the switching frequency of the pulse- width-modulation. An other significant drawback of the switch mode operation is the electromagnetic interference [EMI] produced due to large di/dt and dv/dt caused by a switch-mode operation [1]. These shortcomings of switch-mode converters are exacerbated if the switching frequency is increased in order to reduce the converter size and weight, and hence to increase the power density. Therefore, to realize high switching frequencies in converters, the aforementioned shortcomings are minimized if each switch in a converter changes its status (from on to off or vice versa) when the voltage across it and/or the current through it is zero at the switching instant. To illustrate further the problems associated with switch-mode operation, consider one of the legs of a full bridge dc-dc converter or a dc-ac inverter as shown in Fig.l. TT / t, Ad, vd + ul/ // I A D, '. Fig. 1. One inverter leg.The output current can be in either direction and can be assumed to have a constant magnitude Io due to the load inductance, during the very brief switching interval. The linearized voltage and current vaweforms, for example, for the lower switch T2 are shown in Fig.2.a. /- Turn off - i la) SOA (safe-operating area) j» Turn- Fig. 2. Switch-mode inductive current switchings. Here, the average value the switching loss P^, being proportional to the switching frequency, limits how high the switching frequency can be pushed, without significantly degrading the system efficiency. With the availability of fast switches, the present limit seems to be up to approximately 500 kHz with a resonable energy efficiency. Another significant disadvantage of the switch-mode operation, is that it results in large di/dt and dv/dt due to fast switching transition required to keep the switching losses in the switch as low as possible. Diodes with poor reverse recovery characteristics significantly add to this phenomenon, which produces electromagnetic interference[EMT. -Vll-Zero Voltage And Zero Current Switchings Switching frequencies in the megahertz range, even tens of megahertz, are being contemplated to reduce the size and the weight of transformers and filter components and, hence, to reduce the cost as well as the size and the weight of power electronics converters. The switch stresses can be reduced by connecting simple dissipative snubber circuits(consisting of diodes and passive components) in series and in parallel with the switch-mode converters. Such snubber circuits are shown in Fig. 3. a and the switching loci that result in reduced switch stresses are shown in Fig. 3.b. However, these dissipative snubbers shift the switching power loss from the switch to the snubber circuit, and therefore do not provide a reduction in the overall switching power loss. «T2 Vy Turn-on / /C Turn-< - v-n lb) r` ı i 5 D, 1 1 -Turn-on snubber (at Fig. 3. Dissipative snubbers: (a) snubber circuits, (b) switching loci with snubbers. -Vlll-In contrast to dissipative snubbers in switch-mode convertes, the combination of proper converter topologies and switching strategies can overcome if the problems of switching stresses, switching power losses, and the EMI by turning on and off each of the converter switches when either the switch voltage or the switch current is zero. Ideally, both the switch voltage and current should be zero when the switching transition occurs. Classification Of Resonant Converters The resonant converters are defined here as the combination of converter topologies and switching strategies that result in zero-voltage and/or zero-current switchings. One way to categorize these converters is as follows: 1. Load-Resonant converters 2. Resonant-Switch converters 3. Resonant-dc-Link converters 4. High-frequency-link Integral-half-cycle converters Load Resonant Converters These converters consist of an L-C resonant tank circuit. Oscillating voltage and current, due to L-C resonance in the tank, are applied to the load, and the converter switches can be switched at zero voltage and/or zero current. Either a series L-C or a parallel L-C circuit can be used. In these converter circuits, the power flow to the load is controlled by the resonant tank impedance, which in turn is controlled by the switching frequency fs in comparison to the resonant frequency f0 of the tank. These dc-to-dc and dc-to- ac converters can be subclassified as follows: 1. Voltage-source series-resonant converters a. Series-loaded resonant(SLR) converters b. Parallel-loaded resonant(PLR) converters c. Hybrid-resonant converters 2. Class-E resonant converters Resonant Switch Converters In certain switch-mode converter topologies, an L-C resonance can be utilized primarily to shape the switch voltage and current to provide zero- voltage and/or zero-current switchings. In such resonant switch converters, during one switching frequency time period, there are resonant as well as non- resonant operating intervals. A majority of such converters can be divided into three switching categories: 1. Zero-Current-Switching(ZCS) topology where the switch turns on and off at zero current. The peak resonant current flows through the switch voltage remains the same as in its switch-mode counterpart. -IX-2. Zero-Voltage-Switching(ZVS) topology where the switch turns on and off at zero voltage. The peak resonant voltage appears across the switch, but the peak switch current remains the same as in its switch-mode counterpart. 3. Zero- Voltage-Switching, clamped-voltage(ZVS-CV) topology where the switch turns on and off at zero voltage. However, a converter of this topology consists of at least one converter leg made up of two such switches. The peak switch voltage remains the same as in its switch-mode counterpart, but the switch current is generally higher. Resonant-dc-link Converters In the conventional switch-mode PWM dc-to-ac inverters, the input Vd to the inverter is a fixed magnitude dc, and the sinusoidal output(single-phase or three-phase) is obtained by switch-mode PWM switchings. However, in the resonant-dc-link converters, the input voltage is made to oscillate around Vd by means of an L-C resonance so that the input voltage remains zero for a finite duration during which the status of the inverter switches can be changed, thus resulting in zero-voltage switching. High-Frequency-Link Integral-Half-Cycle Converters If the input to a single-phase or three-phase inverter is a high-frequency sinusoidal ac, then by using bidirectional switches it is possible to synthesize a low-frequency ac of adjustable magnitude and frequency or an adjustable magnitude dc, where the switches are turned on and off at the zero-crossings of the voltage. -x- 83