中文摘要：

并联是提高永磁直驱风电系统功率等级的一种有效方法,但同时也会带来环流、电流分配不均等诸多问题。针对这些问题,提出一种永磁直驱风电系统的新型拓扑,建立了它的平均模型,并对其存在的环流现象进行了分析,证明了新型拓扑结构机侧环流和网侧环流是互相独立的,并阐明了环流产生的根本机理,即环流是由并联变换器三相桥臂占空比零轴分量的不一致造成的。在上述分析的基础上提出一种环流控制器,在不影响其它被控量且不增加硬件开销的前提下抑制了机侧环流和网侧环流,解决了环流引起的不均流、波形畸变等问题,提高了系统的可靠性和效率。仿真和实验结果验证了所提方法的正确性。

英文摘要：

Parallel connection technique can improve the power capacity of the permanent-magnet-direct-drive wind power system effectively.But it causes some problems,such as circulating current,unbalanced current distribution,etc.To solve these problems,this paper proposed a new topology of permanent-magnet-direct-drive wind power system.Its average model and circulating current were analyzed.It can be seen that the generator-side and line-side circulating currents are independent with each other.Moreover,the circulating current is caused by the zero-axis component discrepancy of the three-phase bridge duty between the parallel modules.Based on the above analysis,the circulating current controller was proposed to suppress the circulating current.It not only has no influence on other controlled variables,but also does not increase the hardware cost.This method suppresses the generator-side and line-side circulating currents effectively and improves the reliability and efficiency of the system.The simulation and experimental results verify the validity of the proposed method.