Integrated Microinverter and Storage for Portable Photovoltaic systems

Recent emergence of battery technology has resulted in increased interest in design of an integrated portable photovoltaic panel with a battery pack for stand-alone and grid-connected system. Lithium-ion batteries appear to be an optimal candidate due to high energy density, long cycling life, deep discharge ability, low self-discharge and different shapes such as cylindrical or prismatic styles to obtain an integrated design. The physical integration of the PV panel with batteries must feature scalability, adaptability and easy installation. These requirements validate the microinverter as desired power electronic solution for the proposed system. To eliminate the issues of the PV power fluctuation, various microinverter topologies have been proposed in this dissertation which integrate a battery as a storage element with PV panel. The integrated battery is dedicated to eliminating the intermittent and the excessive power concerns in PV system. This allows the PV, local energy storage, and a smart integrated micro-inverter to be consolidated and mounted as one module on the back of the PV panel. The efficient energy management system will provide stable predictable power in grid-connected applications. The topologies feature either five or six power flow scenarios based on the power generated by PV module, the grid requirement and the battery state of charge. The power flow scenarios can be as follows: 1) Only PV module providing power to the grid. 2) Only battery providing power to the grid. 3) PV module providing power to the grid while charging the battery. 4) Both PV and battery providing power to the grid. 5) PV module charging the battery. 6) The grid charging the battery. All power flow scenarios are achieved with single-stage conversion between three ports with faster response, low component counts, compact size and centralized control to manage the power among the ports