An input-parallel and output-series-parallel phase-shift full-bridge converter with maximum power point tracking for wind turbine

This paper proposes a novel topology for a DC/DC conversion system, which consists of three phase-shift H-bridge converters. The three input sides of the H-bridge converters are paralleled directly, while the output sides can be connected in parallel and/or series through a switching mechanism, which provides nine different connection configurations determined by the value of the input voltage generated and rectified from a wind-turbine generator. Lower cut-in voltage can be achieved by connecting the output sides of the three H-bridge converters in series to obtain high voltage gain. When rated power of the wind turbine is reached, the generator provides highest voltage, the output sides of the three H-bridge connect in series to share the load current. Thus, the main aims of the proposed converter are to provide a wider available operation range of the wind turbine and to obtain higher efficiency of the converter system over the whole operation range. Nevertheless, using three individual converters with different rated power is cost inefficiency compared with working by one single converter, and this is a disadvantage of the proposed system. The well-known load-disturbance method is used to track the available maximum power generated from the wind turbine. A 5kW prototype was built for evaluation and test. The experimental results demonstrated the validity of the proposed converter.