A switchable cascaded multi-dc-branch for permanent magnet synchronous generator in wide speed range on wind energy conversion system

Traditional power converters for direct-drive permanent magnet wind power system limit the speed range of the permanent magnet generator, which affect the efficiency of wind energy utilization. Therefore the variable multi-dc-branch topology for wide-speed-operation direct-drive permanent magnet synchronous is proposed. This variable topology can not only extend the generator speed by adjusting the series dc branch number with the speed change in a finite bus voltage domain, but also reduce the running parallel branch with the reduced wind speed which can increase the branch fault tolerance. The variable multi-dc-branch topology is analyzed in this paper and the method of extending the generator speed with this topology is studied. The simulation and experimental results show that the variable multi-dc-branch topology is feasibility and using this topology to extend the generator speed is availability.