DESIGN OF CONVERTER FOR LOW POWER PHOTOVOLTAIC CONVERSION SYSTEM

ABSTRACT: The solar energy conversion system is an alternative for conventional power generating system. It has no running cost due to freely available and non polluting solar radiations. The voltage which is available from solar array is variable and to obtain a stable voltage from solar panels, DC-DC converters are required for constant power production. There are mainly three converters namely Buck, Boost and Buck-Boost converters which can be used for either increasing or decreasing the voltage. This paper presents mobile charging circuit with a PV source. The circuit structure of the proposed system adopts buck converter combined PWM MPPT technique. In this research, buck converter is used as a charger for charging mobile battery. The input voltage can typically change from (12V) initially, down to (5V), and provide a regulated voltage within the range of the 4.5V required for the charging of mobile batteries

Dynamic modeling of a dual active bridge DC to DC converter with average current control and load-current feed-forward

Bidirectional power flow is needed in many power conversion systems like energy storage systems, regeneration systems, power converters for improvement of the power quality and some DC-DC applications where bidirectional high power conversion and galvanic isolation are required. The dual active bridge (DAB) is an isolated, high voltage ratio DC-DC converter suitable for high power density and high power applications, being a key interface between renewable energy sources and energy storage devices. This paper is focused on the modeling and control design of a DC-DC system with battery storage based on a DAB converter with average current mode control of the output current and output voltage control. The dynamic response of the output voltage to load steps is improved by means of an additional load-current feed-forward control loop. An analytical study of the load-current feed-forward is presented and validated by means of both simulations and experimental results.This work was supported by the Spanish Ministry of Economy and Competitiveness under grant ENE2012-37667-C02-01.Guacaneme Moreno, JA.; Gabriel Garcerá; Figueres Amorós, E.; Patrao Herrero, I.; González Medina, R. (2015). Dynamic modeling of a dual active bridge DC to DC converter with average current control and load-current feed-forward. International Journal of Circuit Theory and Applications. 43(10):1311-1332. https://doi.org/10.1002/cta.2012S131113324310Vazquez, S., Lukic, S. M., Galvan, E., Franquelo, L. G., & Carrasco, J. M. (2010). Energy Storage Systems for Transport and Grid Applications. IEEE Transactions on Industrial Electronics, 57(12), 3881-3895. doi:10.1109/tie.2010.2076414De Doncker, R. W. A. A., Divan, D. M., & Kheraluwala, M. H. (1991). A three-phase soft-switched high-power-density DC/DC converter for high-power applications. IEEE Transactions on Industry Applications, 27(1), 63-73. doi:10.1109/28.67533Kheraluwala, M. N., Gascoigne, R. W., Divan, D. M., & Baumann, E. D. (1992). Performance characterization of a high-power dual active bridge DC-to-DC converter. IEEE Transactions on Industry Applications, 28(6), 1294-1301. doi:10.1109/28.175280Chang, Y.-H., & Wu, K.-W. (2012). A gain/efficiency-enhanced bidirectional switched-capacitor DC-DC converter. International Journal of Circuit Theory and Applications, 42(5), 468-493. doi:10.1002/cta.1863Li H Liu D Peng FZ Gui-Jia S Small Signal Analysis of A Dual Half Bridge Isolated ZVS Bi-directional DC-DC converter for Electrical Vehicle Applicat 36th IEEE Power Electronics Specialists Conference 2005 2777 2782Chiu, H.-J., Yao, C.-J., & Lo, Y.-K. (2009). A DC/DC converter topology for renewable energy systems. International Journal of Circuit Theory and Applications, 37(3), 485-495. doi:10.1002/cta.475Doishita K Hashiwaki M Aoki T Kawagoe Y Murakami N Highly reliable uninterruptible power supply using a bi-directional converter The 21st International Telecommunication Energy Conference (INTELEC '99), Copenhagen 1999 10.1109/INTLEC.1999.794066Krismer F Biela J Kolar JW A comparative evaluation of isolated bi-directional DC/DC converters with wide input and output voltage range 40th IAS Annual Meeting Industry Applications Conference 2005 1 599 606Aggeler D Biela J Inoue S Akagi H Kolar JW Bi-Directional Isolated DC-DC Converter for Next-Generation Power Distribution - Comparison of Converters using Si and SiC Devices Power Conversion Conference-Nago 2007 510 517Krishnamurthy HK Ayyanar R Building Block Converter Module for Universal (AC-DC, DC-AC, DC-DC) Fully Modular Power Conversion Architecture IEEE Power Electronics Specialists Conference 2007 483 489Romero-Cadaval, E., Spagnuolo, G., Franquelo, L. G., Ramos-Paja, C. A., Suntio, T., & Xiao, W. M. (2013). Grid-Connected Photovoltaic Generation Plants: Components and Operation. IEEE Industrial Electronics Magazine, 7(3), 6-20. doi:10.1109/mie.2013.2264540Yu, X., She, X., Ni, X., & Huang, A. Q. (2014). System Integration and Hierarchical Power Management Strategy for a Solid-State Transformer Interfaced Microgrid System. IEEE Transactions on Power Electronics, 29(8), 4414-4425. doi:10.1109/tpel.2013.2289374Liserre, M., Sauter, T., & Hung, J. (2010). Future Energy Systems: Integrating Renewable Energy Sources into the Smart Power Grid Through Industrial Electronics. IEEE Industrial Electronics Magazine, 4(1), 18-37. doi:10.1109/mie.2010.935861Mi, C., Bai, H., Wang, C., & Gargies, S. (2008). Operation, design and control of dual H-bridge-based isolated bidirectional DC–DC converter. IET Power Electronics, 1(4), 507. doi:10.1049/iet-pel:20080004Friedemann A Krismer F Kolar JW Design of a Minimum Weight Dual Active Bridge Converter for an Airborne Wind Turbine System Proceedings of the 27th Applied Power Electronics Conference and Exposition (APEC) 2012Krismer, F., & Kolar, J. W. (2010). Accurate Power Loss Model Derivation of a High-Current Dual Active Bridge Converter for an Automotive Application. IEEE Transactions on Industrial Electronics, 57(3), 881-891. doi:10.1109/tie.2009.2025284Hengsi Qin, & Kimball, J. W. (2012). Generalized Average Modeling of Dual Active Bridge DC–DC Converter. 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(1986). Near-Optimum Dynamic Regulation of DC-DC Converters Using Feed-Forward of Output Current and Input Voltage with Current-Mode Control. IEEE Transactions on Power Electronics, PE-1(3), 181-192. doi:10.1109/tpel.1986.4766303Qin H Kimball JW Closed-loop control of DC-DC dual active bridge converters driving single-phase inverters IEEE Energy Conversion Congress and Exposition (ECCE) 2012 173 17

Dynamic modeling of DC-DC converters with peak current control in double-stage photovoltaic grid-connected inverters

In photovoltaic (PV) double-stage grid-connected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. In the proposed overall control structure the output voltage of the DC-DC converter is regulated by the grid-connected inverter. Therefore, the inverter may be considered as a constant voltage load for the development of the small-signal model of the DC-DC converter, whereas the PV panel is considered as a negative resistance. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. The theoretical analysis is corroborated by frequency response measurements on a 230 W experimental inverter working from a single PV panel. The inverter is based on a Flyback DC-DC converter operating in discontinuous conduction mode (DCM) followed by a PWM full-bridge single-phase inverter. The time response of the whole system (DC-DC + inverter) is also shown to validate the concept. Copyright © 2011 John Wiley & Sons, Ltd. In photovoltaic (PV) double-stage gridconnected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.This work was supported by the Spanish Ministry of Science and Innovation (MICINN) under grant ENE2009-13998-C02-02. The company AUSTRIAMICROSYSTEMS co-financed this project.Garcerá Sanfeliú, G.; González Medina, R.; Figueres Amorós, E.; Sandía Paredes, J. (2012). Dynamic modeling of DC-DC converters with peak current control in double-stage photovoltaic grid-connected inverters. International Journal of Circuit Theory and Applications. 40(8):793-813. https://doi.org/10.1002/cta.756S793813408Carrasco, J. M., Franquelo, L. G., Bialasiewicz, J. T., Galvan, E., PortilloGuisado, R. C., Prats, M. A. M., … Moreno-Alfonso, N. (2006). Power-Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey. IEEE Transactions on Industrial Electronics, 53(4), 1002-1016. doi:10.1109/tie.2006.878356Kjaer, S. B., Pedersen, J. K., & Blaabjerg, F. (2005). A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules. IEEE Transactions on Industry Applications, 41(5), 1292-1306. doi:10.1109/tia.2005.853371Ridley, R. B. (1991). A new, continuous-time model for current-mode control (power convertors). IEEE Transactions on Power Electronics, 6(2), 271-280. doi:10.1109/63.76813Femia, N., Petrone, G., Spagnuolo, G., & Vitelli, M. (2005). Optimization of Perturb and Observe Maximum Power Point Tracking Method. IEEE Transactions on Power Electronics, 20(4), 963-973. doi:10.1109/tpel.2005.850975Hua, C., & Lin, J. (2004). A modified tracking algorithm for maximum power tracking of solar array. Energy Conversion and Management, 45(6), 911-925. doi:10.1016/s0196-8904(03)00193-6Tan, Y. T., Kirschen, D. S., & Jenkins, N. (2004). A Model of PV Generation Suitable for Stability Analysis. IEEE Transactions on Energy Conversion, 19(4), 748-755. doi:10.1109/tec.2004.827707Femia, N., Petrone, G., Spagnuolo, G., & Vitelli, M. (2009). A Technique for Improving P&O MPPT Performances of Double-Stage Grid-Connected Photovoltaic Systems. IEEE Transactions on Industrial Electronics, 56(11), 4473-4482. doi:10.1109/tie.2009.2029589Chiu, H.-J., Huang, H.-M., Yang, H.-T., & Cheng, S.-J. (2008). An improved single-stage Flyback PFC converter for high-luminance lighting LED lamps. International Journal of Circuit Theory and Applications, 36(2), 205-210. doi:10.1002/cta.404Chiu, H.-J., Yao, C.-J., & Lo, Y.-K. (2009). A DC/DC converter topology for renewable energy systems. International Journal of Circuit Theory and Applications, 37(3), 485-495. doi:10.1002/cta.475Martins DC Demonti R Photovoltaic Energy Processing for Utility Connected System 1292 1296 10.1109/IECON.2001.975968www.focus.ti.com/lit/ml/slup127/slup127.pdf2003 http://www.fairchildsemi.comEsram, T., & Chapman, P. L. (2007). Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques. IEEE Transactions on Energy Conversion, 22(2), 439-449. doi:10.1109/tec.2006.874230Liserre, M., Blaabjerg, F., & Hansen, S. (2005). Design and Control of an LCL-Filter-Based Three-Phase Active Rectifier. IEEE Transactions on Industry Applications, 41(5), 1281-1291. doi:10.1109/tia.2005.853373Liserre, M., Teodorescu, R., & Blaabjerg, F. (2006). Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values. IEEE Transactions on Power Electronics, 21(1), 263-272. doi:10.1109/tpel.2005.861185Figueres, E., Garcera, G., Sandia, J., Gonzalez-Espin, F., & Rubio, J. C. (2009). Sensitivity Study of the Dynamics of Three-Phase Photovoltaic Inverters With an LCL Grid Filter. 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Synthesis and analysis of three-port dc/dc converters with two bidirectional ports based on power flow graph technique

This paper presents a systematic topological study to derive all possible basic and non-isolated three-port converters (TPCs) using power flow diagrams. Unlike most reported TPCs with one bidirectional port, this paper considers up to two bidirectional ports and provides a comprehensive analytical tool. This tool acts as a framework for all power flow combinations, selection, and design. Some viable converter configurations have been identified and selected for further analysis

Pem fuel cell modeling and converters design for a 48 v dc power bus

Fuel cells (FC) are electrochemical devices that directly convert the chemical energy of a fuel into electricity. Power systems based on proton exchange membrane fuel cell (PEMFC) technology have been the object of increasing attention in recent years as they appear very promising in both stationary and mobile applications due to their high efficiency, low operating temperature allowing fast startup, high power density, solid electrolyte, long cell and stack life, low corrosion, excellent dynamic response with respect to the other FCs, and nonpolluting emissions to the environment if the hydrogen is obtained from renewable sources. The output-voltage characteristic in a PEMFC is limited by the mechanical devices which are used for regulating the air flow in its cathode, the hydrogen flow in its anode, its inner temperature, and the humidity of the air supplied to it. Usually, the FC time constants are dominated by the fuel delivery system, in particular by the slow dynamics of the compressor responsible for supplying the oxygen. As a consequence, a fast load transient demand could cause a high voltage drop in a short time known as oxygen starvation phenomenon that is harmful for the FC. Thus, FCs are considered as a slow dynamic response equipment with respect to the load transient requirements. Therefore, batteries, ultracapacitors or other auxiliary power sources are needed to support the operation of the FC in order to ensure a fast response to any load power transient. The resulting systems, known as FC hybrid systems, can limit the slope of the current or the power generated by the FC with the use of current-controlled dc-dc converters. In this way, the reactant gas starvation phenomena can be avoided and the system can operate with higher efficiency. The purpose of this thesis is the design of a DC-DC converter suitable to interconnect all the different elements in a PEMFC-hybrid 48-V DC bus. Since the converter could be placed between elements with very different voltage levels, a buck-boost structure has been selected. Especially to fulfill the low ripple requirements of the PEMFCs, but also those of the auxiliary storage elements and loads, our structure has inductors in series at both its input and its output. Magnetically coupling these inductors and adding a damping network to its intermediate capacitor we have designed an easily controllable converter with second-order-buck-like dominant dynamics. This new proposed topology has high efficiency and wide bandwidth acting either as a voltage or as a current regulator. The magnetic coupling allows to control with similar performances the input or the output inductor currents. This characteristic is very useful because the designed current-controlled converter is able to withstand shortcircuits at its output and, when connected to the FC, it facilitates to regulate the current extracted from the FC to avoid the oxygen starvation phenomenon. Testing in a safe way the converter connected to the FC required to build an FC simulator that was subsequently improved by developing an emulator that offered real-time processing and oxygen-starvation indication. To study the developed converters and emulators with different brands of PEMFCs it was necessary to reactivate long-time inactive Palcan FCs. Since the results provided by the manual reactivation procedure were unsatisfactory, an automatic reactivation system has been developed as a complementary study of the thesis.En esta tesis se avanzo en el diseño de un bus DC de 48 V que utiliza como elemento principal de generación de energía eléctrica una pila de combustible. Debido a que la dinámica de las pilas de combustible están limitadas por sus elementos mecánicos auxiliares de control una variación rápida de una carga conectada a ella puede ocasionar daños. Es por esto que es necesario utilizar elementos almacenadores de energía que puedan suministrar estas rápidas variaciones de carga y convertidores para que gestionen de una forma controlada la potencia del bus DC. Durante la realización de pruebas de los convertidores es de gran importancia utilizar emuladores o simuladores de pilas de combustibles, esto nos permite de una forma económica y segura realizar pruebas criticas antes de conectar los convertidores a la pila. Adicionalmente una nueva topologia de convertidor fue presentada y ésta gestionará la potencia en el bu