iosr-JEEE   Volume-9 ~ Issue-3 ~ May-June 2014

Abstract: comparative study of the flying capacitor three level buck converter and a modified flying capacitor three level converter is done here. And analysis of the modified flying capacitor three level buck converter is done from the waveforms obtained. The main benefits of this topology is reduction in size of the converter and also higher efficiency. The conventional and the proposed circuits are simulated using PSIM.
Index Terms: Flying capacitor Buck converter ,dynamic response.

[1]. Lisheng Shi, BhanuPrashantBaddipadiga,MehdiFerdowsi,andMariesa L, "Improving the Dynamic Response of a Flying-Capacitor
Three-Level Buck Converter," IEEE Trans. Power Electron., vol. 28,no. 5, May. 2013.
[2]. J. Zhao, T. Sato , T. Nabeshima, and T. Nakano, "Steady-state and dynamic analysis of a buck converter using a hysteretic
PWM control," in Proc. IEEE 35th Annu. Appl. Power Electron. Spec. Conf., Jun. 2004, vol. 5, pp. 3654–3658.
[3]. V. Yousefzadeh, E. Alarc´on, and D. Maksimovic, "Three-level buck converter for envelope tracking applications," IEEE
Trans. Power Electron., vol. 21, no. 2, pp. 549–552, Mar. 2006.

Abstract: This paper presents power loss comparison of single and two-stage grid-connected photovoltaic (PV) systems based on the loss factors of double line-frequency voltage ripple (DLFVR), fast irradiance variation + DLFVR, fast dc load variation + DLFVR, limited operating voltage range + DLFVR, and over- all loss factor combination. These loss factors will result in power deviation from the maximum power points. In this paper, both single-stage and two-stage grid-connected PV systems are considered. All of the effects on a two-stage system are insignificant due to an additional maximum power point tracker, but the tracker will reduce the system efficiency typically about 2.5%. The power loss caused by these loss factors in a single-stage grid-connected PV system is also around 2.5%; that is, a single-stage system has the merits of saving components and reducing cost, and does not penalize overall system efficiency under certain operating voltage ranges. Simulation results with the MATLAB software package and confirmed the analysis.
Index Terms: Loss factor, power loss comparison, single-stage grid-connected photovoltaic (PV) system, two-stage grid-connected PV system.

[1]. T.-F. Wu, C.-H. Chang, Y.-D. Chang, and K.-Y. Lee, "Power loss analysis of grid-connection photovoltaic systems," in Proc. Power Electronics and Drive Systems (PEDS) Conf., 2009, pp. 326–331.
[2]. T. A. Huld, M. Suri, R. P. Kenny, and E. D. Dunlop, "Estimating PV performance over large geographical regions," in Proc. 31st IEEE. Photovoltaic. Spec. Conf., 2005, pp. 1679–1682.
[3]. N. Okada, S. Yamanaka, H. Kawamura, and H. Ohno, "Diagnostic method of performance of a PV module with estimated power output in considering four loss factors," in Proc. 31st IEEE Photovoltaic. Spec. Conf., 2005, pp. 1643–1646.
[4]. R. Suzuki, H. Kawamura, S. Yamanaka, H. Ohno, and K. Naito, "Lossfactors affecting power generation efficiency of a PV module," in Proc.29th IEEE. Photovoltaic. Spec. Conf., 2002, pp. 1557–1560.
[5]. N. Okada, S. Yamanaka, H. Kawamura, and H. Ohno, "Energy loss of photovoltaic system caused by irradiance and incident angle," in Proc.3rd IEEE Photovoltaic Energy Convers. World. Conf., 2003, pp. 2062–2065.