一种二极管箝位级联拓扑在直驱风电系统中的应用研究

Research on a Kind of Diode-clamped Cascade Topology in Direct-drive Wind Power System

随着风电机组单机容量的不断增大,多电平变流器的应用得到了广泛关注。采用的二极管箝位五电平级联H桥拓扑,结合了二极管箝位型多电平和级联H桥多电平的优势,需要较少的箝位二极管和独立直流电源,即可进一步提高输出电压等级,使用移相变压器和12脉波整流器作为输入电路,对其在使用多相永磁同步发电机的直驱风电系统中的应用进行了初步探索。基于拓扑提出了消谐波SPWM和载波相移SPWM相结合的调制方法,能够方便地对二极管箝位级联拓扑进行控制,可以进一步提高等效载波频率,降低器件损耗和滤波器体积。仿真和实验结果证实了所采用的拓扑及其控制方法的有效性。

With fast increasing of single wind turbine volume,multilevel converter has been paid much attention. Topology of diode-clamped 5-level cascade H-bridge combines the advantages of diode-clamped multilevel and cascade H-bridge multilevel converter, can further improve the output voltage rating,require few clamping diodes and separated DC-source;With phase-shifting transformer and 12-pulse rectifier, the topology may be potentially applied in direct- drive wind power system using polyphased permanent magnet synchronous generator （PMSG）. The modulation strategy integrating sub-harmonic SPWM and carrier phase-shifted SPWM is adopted based on the topology, can control the diode-clamped 5-level cascade H-bridge converter expediently, enhance the equivalent carrier frequency, lower switching losses and filter volume. The validity of the topology and its control principle adopted is verified by simulation and experiment results.