Power devices loading in multilevel converters for 10 MW wind turbines

Several promising multilevel converter solutions for 10 MW wind turbines using permanent magnet synchronous generators are proposed, designed and compared both with one-stage gear-box drive and direct drive systems. The current and loss distributions, as well as the utilization of power devices in each converter are analyzed based on simulation results. Finally, the total loss and efficiency comparison are given. It is concluded that five-level and three-level H-bridge topologies show higher efficiency either in the power conversion or in the device utilization compared to the three-level Neutral-Point-Clamped topology with both the direct-drive and one-stage gear box drive systems.