A control circuit small wind turbines with low harmonic distortion and improved power factor

This paper presents the application of average current mode control to reduce the THD_i and increase the PF in a Three-Phase Boost Rectifier driving a small wind turbine. It is used as input stage of small wind turbines with permanent magnet synchronous generators operating at variable speed. The Boost Rectifier´s output is connected to an inverter which feeds the energy to a distribution power grid. The operation in discontinuous conduction mode allows significantly reducing the Total Harmonic Distortion of the current in the small wind turbine. However, it is necessary to add an input filter so that the switching ripple doesn´t arrive to the small wind turbine. It is evaluated the convenience of the current sensors placement in the DC side of the rectifier or at the output of the generator. The results demonstrate that it is better to place the sensors in the output of the generator, because it is achieved smaller THD_i and higher PF.