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Title: Topology Studies and Control of Microinverters for Photovoltaic Applications
Authors: LI YANLIN
Keywords: Microinverter, AC module, Flyback-CCM Inverter, Active Power Decoupling, Parallel Power Processing, Current shaping
Issue Date: 25-Jan-2013
Citation: LI YANLIN (2013-01-25). Topology Studies and Control of Microinverters for Photovoltaic Applications. ScholarBank@NUS Repository.
Abstract: In this research, microinverter topologies to achieve high conversion efficiency with trade-off between potential low cost and long lifetime are investigated. Simple and effective control schemes have also been proposed for the proposed topologies in order to meet both PV and grid side requirements. Firstly, a low cost flyback inverter operating in continuous conduction mode (flyback-CCM) is proposed to reduce device currents and improve efficiency compared to the popular flyback-DCM (discontinuous conduction mode) inverter. A net weighted average efficiency improvement of 8% has been achieved. In addition, the control challenges with flyback-CCM inverter are investigated and two controllers, i.e. one cycle control (OCC) and average current control (ACC) are proposed to achieve the desired current shaping performance under varying operating conditions. An issue concerning the use of the decoupling electrolytic capacitor which causes reduction in lifetime is investigated next. A Parallel Power Processing (P3) scheme for active power decoupling with targets of long lifetime while maintaining a good efficiency has been proposed. A simple dual loop control has been proposed to achieve output current shaping and active power decoupling control. Steady state and dynamic operation of the scheme has been studied through simulations and the current tracking performance verified by experiment. The proposed P3 scheme has the advantages of using a long life film capacitor for decoupling instead of an electrolytic capacitor and processing only 31.8% of the input power twice to realize the active power decoupling.
Appears in Collections:Ph.D Theses (Open)

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