Design and implementation of a grid-tied wind power micro-inverter

Small wind turbine generator (WTG) below 300 W capacity is suitable to generate power in residential or city area, where no large space for installing kilowatt scale WTG. The modularised micro-inverter which can feed WTG power to the grid directly has the merit of increasing the installed flexibility and omitting the battery in this application. This study proposes a grid-tied micro-inverter combining the boost and flyback-based inverter topology and specially designed for the small WTG with permanent magnetic (PM) generator. The boost converter is used to step up the input voltage and track the maximum power point (MPP) of the WTG. The flyback-based inverter is used to feed power to the grid with unity power factor. A fast MPP tracking (MPPT) method is presented to track the wind power to fit for the wind speed with fast variation. The variable frequency peak current mode control method is adopted for the control of the flyback-based inverter. An interleaving technique is also applied to the inverter for increasing its power capacity. Quantitative controller design of the boost converter with the WTG input and the grid-tied flyback-based inverter is presented. A 240 W experimental system is built. A WTG emulator implemented with the M-G set is developed for testing the proposed system. Some simulation and measured results are provided for demonstrating the effectiveness of the proposed system.