COMPARITIVE STUDY OF TWO SINGLE PHASE AC-DC BOOST CONVERTER TOPOLOGIES BASED ON POWER QUALITY PERFORMANCE INDICES

                                      Saranya Natarajan ¹, B.V.Manikandan ²

¹PG student- Department of EEE – Mepco Schlenk Engineering College, Sivakasi Tamilnadu, India.

²Professor- Department of EEE – Mepco Schlenk Engineering College, Sivakasi Tamilnadu, India.

   
 Single-phase switch mode AC-DC converters are being used as front-end rectifiers for a variety of applications due to the advantages of high efficiency and power density. These classical converters, however, draw non-sinusoidal input ac currents leading to low input power factors and injection of harmonics into the utility lines. Harmonics have a negative effect in the operation of electrical system and hence they need to be removed. Research into passive and active techniques for input current wave shaping has highlighted their inherent drawbacks. Passive filters have the demerits of fixed compensation, large size and resonance whereas active filters improve the power quality of the input current and consequently they improve the power factor. The Power Factor Correction (PFC) which is an active filter based method provides efficient means for reducing harmonics. These circuits reduce harmonics and consequently they improve power factor. This work presents a comparative study of two topologies of single-phase AC-DC boost converters with improved power factor correction (PFC).Both open loop and closed loop control modes are discussed for the considered two converter topologies. Simulation studies have been carried out using SIMULINK tool in MATLAB 7.4 environment.

                                               

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MODIFIED HYBRID CASCADED H- BRIDGE MULTILEVEL INVERTER

                                                                A.Rajkumar

PG student- Department of EEE - SBM college of Engineering and technology, Dindigul, Tamilnadu, India

          This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require N dc sources for 2N+1 level. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (example: a battery or a fuel cell stack) with the remaining dc sources being capacitors, which is referred to as Hybrid Cascaded H-bridge Multilevel Inverter (HCMLI) in this paper. It is shown that the inverter can simultaneously maintain the dc voltage level of the capacitors and choose a fundamental frequency switching pattern to produce a nearly sinusoidal output. HCMLI using only a single dc source for each phase is promising for high power motor drive applications as it significantly decreases the number of required dc power supplies, provides high quality output power due to its high number of output levels, and results in high conversion efficiency and low thermal stress as it uses a fundamental frequency switching scheme.

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OPTIMIZATION OF LCL-T RESONANT CONVERTER FOR CC-CV

S.Praveena

PG student- Department of EEE – Mepco Schlenk Engineering College, Sivakasi Tamilnadu, India.

            The LCL-Type series resonant converter has nearly load independent output voltage under some operating conditions. It behaves as a constant current source (CC) when operated under resonant frequency. The output voltage of a CC power supply increases linearly with load resistance. Therefore a constant voltage limit must be incorporated for its use for applications like arc-welding power supplies etc .This limit can be done by incorporating clamp diodes. Since no feedback control is used, the proposed circuit is more reliable and rugged.

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AUTOMATIC DETECTION AND SEGMENTATION OF OPTIC DISC IN RETINAL IMAGES

¹ M.Saradha, ² Mr.A.Athiraja, ³ Dr.A.Askarunisa
¹ PG Student, ² Assistant Professor, ³ Professor & Head
Department of Computer Science and engineering, Vickram College Of Engineering, Enathi, Sivagangai, India.

     Reliable and efficient Optic Disc (OD) localization and segmentation are important tasks in automatic eye disease screening. The Optic Disc (OD) center and margin are typically essential landmarks in establishing a frame of reference for classifying retinal and optic nerve pathology. This project presents a fast and automatic Optic Disc localization and segmentation algorithm developed for retinal disease screening. Morphological filtering is used to remove blood vessels and bright regions other than the Optic Disc from a retinal image. Experimentation was performed on 100 images from the publicly available MESSIDOR database. The OD location methodology succeeded in 78 out of 100 images (78% success). Its efficiency, robustness and accuracy make the OD localization and segmentation scheme described herein suitable for automatic retinal disease screening in a variety of clinical settings. By detecting eye disease early through automated screening algorithms, treatment would become more effective and significant savings in health care costs could be realized

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