APPLICATION OF POSITIVE OUTPUT TRIPLE LIFT LUO CONVERTER FOR PHOTO VOLTAIC SYSTEM USING FUZZY LOGIC CONTROLLER 1 S. SIVARAJESWARI, 2 Dr. D. KIRUBAKARAN Department of Electrical and Electronics Engineering, Anna University ͳ Assistant Professor, Sri Sairam )nstitute Of Technology,Chennai, )ndia, Email: mercygowtham@gmail.com ʹ Professor & (ead, St. Joseph’s )nstitute Of Technology, Chennai, )ndia, Email: kirubad@gmail.com ABSTRACT The positive output triple lift Luo converter is a newly developed advanced DC‐DC converter. The object of this paper is to design and analyze a Fuzzy Logic Controller for positive output triple lift Luo converter (POTLLC). Fuzzy logic is recently increasing emphasis in process control applications. Properties of the proposed controllers are: 1) robustness around the operating point, 2) good performance of transient responses under varying loading conditions and/or input voltage, and 3) invariant dynamic performance in the presence of varying operating conditions. The positive output triple lift Luo converter performs the voltage conversion from positive source voltage to positive load voltage. The simulation model of the positive output triple lift Luo converter with its control circuit was developed in Matlab/Simulink. Key words—pv cells, triple lift converter, voltage lift technique, Arithmetic/Geometric progression, Voltage Transfer Gain, Fuzzy logic controller. 1. INTRODUCTION DC‐DC switching converters are a traditional benchmark for testing nonlinear controllers, due to their inherent nonlinear characteristics. After the pioneering studies of Middle brock [ͳ], a great deal of research has been directed at developing techniques for averaged modeling of different classes of switching converters [ʹ] and for an automatic generation of the averaged models [͵]. The motivation of such studies was the selection of continuous models as simple as possible, but adequate to capture all the main features of the switching converters in terms of stability, dynamic characteristics and effectiveness for designing closed loop regulators. A large number of possible nonlinear controllers have been proposed: among others sliding mode control strategies [Ͷ], nonlinear P) controllers based on the method of extended linearization [ͷ] and nonlinear (∞, controllers [͸]. A recent interesting paper [͹] presents the results of an experimental comparison of five control algorithms on a boost converter: linear averaged controller, feedback linearizing controller, passivity‐based controller, sliding mode controller, sliding mode plus passivity‐based controller are compared along with their adaptive versions in order to cope with the parameter uncertainty due to a load resistance change. Advantages and drawbacks of the proposed control strategies are tested under a fixed output voltage with load variations. All the quoted literature comply with the more general problem of applying nonlinear control techniques to complex real world technical problems such classical approach has undoubtedly the advantage of designing analytical controllers and to evaluate quantitatively their stability bounds. The major problem of the classical approach remains that as the complexity of system increases, our ability to make precise and yet significant statements about its behavior diminishes [ͺ]. )n our opinion the control of switching converter constitutes at the present time a borderline problem, which can be handled both with conventional nonlinear control strategies and with fuzzy logic‐based technologies. Why can be fuzzy logic chosen as an alternative design method to nonlinear controllers? An important answer was given in [ͻ]: a nonlinear controller such as fuzzy logic can be inexpensively implemented with DSP‐based micro‐ controller. As a matter of fact many researchers focused their efforts on the application of fuzzy technology for controlling switching converters. )n [ͻ] the advantages of a low cost micro‐ controller implementation of a fuzzy direct control were pointed out. A model‐ based fuzzy controller ȋfuzzy indirect controlȌ for a Buck converter was proposed in [ͳͲ]. Bonissone [ͳͳ] proposed a successful application for resonant converters, by using suitable scaling factors. )n [ͳͳ] the fuzzy controller performs a variable action depending on the difference between the desired and the actual output voltage. Such implementation considers an optimization of the scaling factors around a single output operating point. Our goal is to implement a robust fuzzy controller that can achieve the following properties: ͳȌ Robustness around the operating point ȋe.g. in the case of a load change; ʹȌ Good dynamic performance ȋi.e. rise time, overshoot, settling time and limited output rippleȌ in the presence of input voltage variations ȋand load changesȌ; and ͵Ȍ )nvariant dynamic performance in presence of varying operating conditions. To the best of our knowledge, property ͳ has been fulfilled in all related literature. Property ʹ requires the synthesis of a complex controller ȋfuzzy or nonlinearȌ able to optimize the transient performance. Property ͵ ȋalong with ) and ʹȌ implies the synthesis of a global controller, with optimized parameters for varying operating conditions. Such task seems to be extremely hard; however we believe that a complex nonlinear controller could be accomplished using fuzzy based controller. )n this paper, using advanced DC‐DC converters fuzzy logic controllers ȋFLCsȌ are developed and presented S. SIVARAJESWARI et al. DATE OF PUBLICATION: NOV 18, 2014 ISSN: 2348-4098 VOL 2 ISSUE 8 NOV-DEC 2014 INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY- www.ijset.in 27