A Series Rectifier and NPC Bridge Converter for Large Permanent Magnet Wind Generator Systems

This paper proposes a modular, medium voltage, high-power converter topology for the large permanent magnet wind generator system, eliminating the grid-side step-up transformer, which is desirable for both onshore and offshore wind turbines. The converter modules are cascaded to achieve medium voltage output. The power factor correction (PFC) circuit enables the generator to achieve unity power factor operation and the generator armature inductance is used as ac-side PFC boost inductance. The conventional low voltage power conversion system will suffer from a high transmission current, which significantly increases losses and cost of the cables as well as voltage drop. So, in this project a permanent magnet wind generator and high-power converter system is proposed, which increases the converter output voltage by cascading converter modules. The proposed system can reduce the cable losses and associated cost for cables and connections by reducing the current, which provides a solution for the power conversion of large wind turbines. The cascaded Series rectifier and NPC bridge converter can successfully transfer power from the generator to the grid with independent active power and reactive power control ability. The entire proposed system will be tested using MATLAB/SIMULINK and the Simulation results show that the proposed system can successfully operate during system start and power transfer.