This paper focused on reviewing the main types of topologies and control strategies employed for the operation of multilevel inverter. Advantages and disadvantages of the topologies and the control techniques in relation to one another are equally reviewed. Recent proposed methods employed to improve the harmonic performance, reduce electromagnetic interference (EMI), lower stress on the power switches, eliminate DC link voltage imbalance and simplify the pulse width modulation control algorithms are fully reviewed. Selective harmonic elimination modulation technique is used in generating the 11-level of output voltage. It is aimed at reducing the total harmonic distortion as low as possible.

Özetçe-Bu bildiride karakter tanıma, korelasyon kullanılarak şablon eşleme yöntemiyle gerçekleştirilmiştir. Yaklaşımımızda, korelasyona ek olarak, korelasyonun işe yaramadığı durumlarda hamming uzaklığı uygulanmaktadır. Bu çalışmada, metin görüntüsü satırlara ve ardından karakterlere temel önişleme teknikleri ile ayrılmaktadır. Bundan sonra, karakter içeren görüntü sınıflandırılmış ve korelasyon yada hamming mesafesi kullanılarak şablon eşleme yöntemi vasıtasıyla metine dönüştürülmüştür. Test aşaması için, toplam 560 karakterli dört metin görüntüsü oluşturulmuştur. Sistem sadece korelasyon için ortalama %72.39 ve korelasyona ek olarak hamming uzaklığı için %94.90'lük tanıma oranlarıyla başarılı çalışmaktadır..Anahtar Kelimelerkarakter tanıma, korelasyon, hamming uzaklığı.Abstract-In this paper, character recognition is carried out using template matching scheme using correlation. In our approach, in addition to correlation, the hamming distance was applied in the scenarios where the correlation fails. In this approach, text image is segmented into lines and then characters by basic pre-processing techniques. After that, the character image is classified and converted into text by template matching scheme using either correlation or hamming distance. For test stage, four text images were created with total of 560 characters. The system works successfully with average recognition rates of 72.39% and 94.90% for correlation only and correlation plus hamming distance, respectively.

<p>This paper studies the suitability of a vector based current control which is mostly employed for its faster response in the reactive current applications of static compnesators (STATCOMs). The current control is mostly achieved using proportional-integral (PI) controllers because of  the advantage of their good tracking and small variations. However, due to the dependency of PI controllers on the modular multilevel converter (MMC) system dynamics, performance variations arise during steady-state STATCOM non-ideal operations. This paper presents an improved MMC based STATCOM control with a d-q compensation algorithm added to the vector based current control. The algorithm is derived to tackle the effects of the dynamics of the MMC and the STATCOM ideal variations without the use of any additional controller. The control is achieved by providing a power compensation in the d,q-axis which injects currents at the input of the PI controllers in order to improve the steady-state performance of the STATCOM control.</p>

No abstract

No abstract