iosr-JEEE   Volume-4 ~ Issue-5

Abstract: Digital control technique is a technique for high frequency switching mode power supply (SMPS). Being widely used in the new generation portable systems, the regulation requirement for high frequency integrated DC-DC switching mode power supply becomes more and more demanding in industry, at very high frequency beyond 10 Mega Hertz range. Analysis and experimental study of buck converter is presented to achieve desired output voltage. The SMPS are emerging in terms of higher dynamic response performances, less output ripple, smaller size and weight. The sliding mode controller is associated with a digital pulse width modulation (DPWM) block to operate at high switching frequency. Sliding mode control (SMC) can reduce the voltage ripple voltage ripple of SMPS. Sliding mode controller will be used by means of analog to digital conversion (ADC) and Digital pulse width modulation (DPWM).

Keywords- Analog to Digital converter(ADC), Digital pulse width modulation(DPWM), Sliding mode control

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Abstract: This paper focuses on the power electronics used in the renewable energy systems especially in the photovoltaic applications. In recent years, interest in natural energy has grown in response to increased concern for the environment. Due to the limitations in the energy available from conventional sources, worldwide attention is being focused on renewable sources of energy. Especially, the energy obtained from solar arrays, becomes more and more important. In grid connected applications, a modular micro-inverter integrated with each photovoltaic (PV) panel can reduce the overall system cost and increase the system reliability and MPPT efficiency. In order to make the PV generation system more flexible and expandable, the backstage power circuit is composed of a high step-up converter and a pulse width-modulation (PWM) inverter. The traditional voltage-fed-full-bridge DC-DC converter suffers high cost, low transformer efficiency and discontinuous input current problems. A current-fed-half-bridge converter topology is utilized herewith continuous input current current, low cost and high efficiency features. A 210 W single-phase PV microinverter system with galvanic isolation is presented. By integrating microinverter to each PV panel, localized MPPT of each individual PV panel can be achieved, thus loading to fast tracking speed and higher system efficiency.

Keywords - PV array, boost-half-bridge, grid-connected photovoltaic (PV) system, maximum power point tracking, repetitive current control.

[1] Yeong-Chau Kuo, Tsorng-Juu Liang and Jiann-Fuh Chen, "Novel Maximum-Power-Point-Tracking Controller for Photovoltaic
Energy Conversion System, "IEEE Transactions on Industrial Electronics, vol.48, no.3, June 2001.
[2] J. Kishore Kumar, V. Lakshmi Devi and H. Rajesh Kumar," Design and Analysis of a Grid-Connected Photovoltaic Power System,"
International Journal of Power System Operation and Energy Management, ISSN (PRINT): 2231 – 4407, Volume-1, Issue-4, 2012.
[3] Billy M. Ho and Henry Shu-Hung Chung, "An Integrated Inverter with Maximum Power Tracking for Grid-Connected PV Systems," IEEE Transactions on Power Electronics, vol. 20, no.4, July 2005.
[4] Eftichios Koutroulis and Frede Blaabjerg," Methods for Optimal Design of Grid Connected PV Inverters," International Journal of
Renewable Energy Research, Vol.1, No.2, May 2011.
[5] Prashant. V. Thakre, V. M. Deshmkh, and Saroj Rangnekar," Performance Analysis of Photovoltaic PWM Inverter with Boost
Converter for Different Carrier Frequencies Using MATLAB," IACSIT International Journal of Engineering and Technology, Vol. 4,
No. 3, June 2012.
[6] Suman Dwari and Leila Parsa," An Efficient High-Step-Up Interleaved DC–DC Converter with a Common Active Clamp,"
IEEETransactions on Industrial Electronics, vol.26, no.1, January 2011.
[7] Tamer T.N. Khatib, Azah Mohamed and Nowshad Amin, "A New Controller Scheme for Photovoltaics Power Generation Systems," European Journal of Scientific Research, ISSN 1450-216X, Vol.33 No.3 (2009), pp.515-524.
[8] CH.Sravan and D.Narasimha Rao, "An Interleaved Boost Converter with Zero-Voltage Transition for Grid Connected PV System,"
International Journal of Emerging trends in Engineering and Development, ISSN 2249-6149 Issue 2, Vol.2, March-2012.
[9] Soeren Baekhoej Kjaer, John K. Pedersen and Frede Blaabjerg, "A Review of Single-Phase Grid-Connected Inverters for
Photovoltaic Modules," IEEE Transactions on Industrial Electronics, vol.41, no.5, September 2005.
[10] Nicola Femia, Giovanni Petrone and Giovanni Spagnuolo, "A Technique for Improving P&O MPPT Performances of Double-Stage
Grid-Connected Photovoltaic Systems," IEEE Transactions on Industrial Electronics, vol.56

Abstract: The efficiency of a diagnosis system depends on the relevance of the information it can be retrieve from the diagnosed plant. The diagnostic system detects, localizes and assesses the damage which may be in the form of delimitation, crack, buckling etc. Optical sensors like Fiber Bragg Grating sensor may be used to determine the strain, temperature and other diagnostic parameters. In real world structural applications the numbers of sensors available are limited which thus requires the need for an efficient sensor optimization algorithm. This paper describes an approach in which a genetic algorithm is used to determine the optimum sensor positions for a diagnostic system. The fundamental issue regarding any diagnostic systems is which data should be processed and how the sensors should be placed. GAs being general purpose optimization algorithms is extremely suitable for such sensor placement problems. In this work the GA is tested using fitness function based on an assigned weight matrix and is developed while setting up the problem to simulate the presence of an effective damage detection system. For initial testing of the GA, we consider that there exists a neural network based identification system for a plate with 20 potential sensors locations.

Keywords: Diagnostic system, Fiber Bragg grating sensors, Genetic algorithm.

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