Mar 14, 2020 | IJMTST |
94 International Journal for Modern Trends in Science and Technology Design of Modified Z-Source DC-DC Converter C Abarna 1 | Dr. S Senthil Kumar 2 1PG Scholar, Department of EEE, Government College of Engineering, Salem, Tamil Nadu, India. 2Associate Professor, Department of EEE, Government College of Engineering, Salem, Tamil Nadu, India. To Cite this Article C Abarna and Dr. S Senthil Kumar, “Design of Modified Z-Source DC-DC Converter”, International Journal for Modern Trends in Science and Technology, Vol. 06, Issue 02, February 2020, pp.:94-99. Article Info Received on 26-January-2020, Revised on 06-February-2020, Accepted on 21-February-2020, Published on 23-February-2020. Sustainable energy application like Solar cells and fuel cells have low output voltage than required load demand. High gain dc-dc converters are used to boost the solar cell output voltage. The z source converter can also use to boost the PV panel voltages. This proposed system presents the modified Impedance source converter topology. The proposed converter gives high voltage gain with low duty ratio, high efficiency and positive polarity for output voltage. Therefore, this converter is good choice for high step up applications. The performance analysis of modified impedance source converter is analyzed by MATLAB/Simulink platform to validate their performance. The time domain simulation results demonstrate that the proposed converter gives improved voltage gain compared to conventional impedance source converter. KEYWORDS: DC-DC power converter, Impedance source, MATLAB/Simulink, Voltage gain. Copyright © 2014-2020 International Journal for Modern Trends in Science and Technology All rights reserved. I. INTRODUCTION Carbon emissions and high rate of oil cost are one of the drawbacks of using non-renewable energy sources So, therecent reaches are about renewable energy sources . Some issues caused by combustion of fossil fuels are • Non-renewable energy source • Global warming • The pour of oil has to lead water pollution and wildlife damage. The renewable energy sources are used for long-term and they are cost effective and highly efficient. The renewable energy source like solar energy are increasingly employed to produce electrical energy . But the solar cells output voltage is lesser than the load demand. So high gain dc-dc converters employed to boost the output voltage of renewable energy sources . The solution of the above problem has been rectified by connecting several photovoltaic cells in series. Anyhow, some cells may be shaded and mismatch in photovoltaic modules cause high power dissipation and decrease the output power . Using dc-dc converters are one of the best methods to boost the output voltage . However, this converter has several switches and high switching stress. The converters use high turn ratio transformer to obtain the large voltage gain . The use transformer causes large leakage inductance. The boost converters give large dc gain voltage but practical implementation of this converter give low efficiency and give large diode reverse recovery problem . On the other hand, to boost this low output voltage Super lift converters are used. But ABSTRACT Available online at: http://www.ijmtst.com/vol6issue02.html International Journal for Modern Trends in Science and Technology ISSN: 2455-3778 :: Volume: 06, Issue No: 02, February 2020 95 International Journal for Modern Trends in Science and Technology C Abarna and Dr. S Senthil Kumar, “Design of Modified Z-Source DC-DC Converter” these converters main switch duty cycle must be high to reach required output voltage. On the other hand, boost converter with coupled inductors may be used to obtain large output voltage. Anyhow, they unstable and inefficient . Conventional impedance source converter has been proposed by Xupeng Fang in the year of 2002. It is used to obtain large dc voltage gain in comparison to the common dc-dc converters . In this paper, an innovative impedance source converter is proposed, based on conventional Z source topology . The main benefits of the proposed converter are • Switch voltage stress is reduced. • They do not have reverse recovery problem because the output diodes are turned on and off softly. • The proposed converter has larger dc voltage gain, in comparison to the conventional Z source converter. • In low switch duty ratio high voltage gain can be obtained. II. EXISTING Z SOURCE CONVERTER CONFIGURATION The conventional Z source converter has two modes of operation. They are voltage fed and current fed. When the power supply is dc voltage source then it is voltage fed converter. When the power supply is dc current source then it is current fed converter. To simplify the analysis, we consider the power flow direction in only source to load. The impedance source converter is nothing two port network which consist of two capacitors and two inductors. The impedance source is a symmetrical converter so the inductors L, L1 and L2 have the same values and the capacitors C, C1 and C2 have same values. The conventional Z source converter is shown in Fig.1. Vc1=Vc2=Vc and (1) VL1=VL2=VL (2) The converter has two patterns of operation. They are 1. S is ON 2. S is OFF When the switch S is ON, the diode D is reverse biased so the source doesn’t give any power to the circuit. At that time the capacitors discharge the energy and inductors charges through the capacitors. The mode the time interval of the converter is D.T. Vc=VL (3) V0=0 (4) When the switch S is OFF, the diode D is forward biased. At that time the capacitors C1 and C2 are charged. The inductors L1 and L2 are discharge the Fig.1 schematic Z source convert energy and the current flow through the load. This mode the time interval of time is (1-D). T Vc=Vi-VL (5) V0=Vi-2VL (6) Where, Vi = Input voltage V0 = Output voltage D = Duty ratio VL= Inductor voltage VC= Capacitor voltage The average output voltage of the converter,
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