基于比例谐振控制器的并联变换器控制研究

Control Strategy for Parallel Converters Based on Proportional Resonance Scheme

逆变器的并联能够增加系统的容量、降低系统成本和提高系统效率。因此,逆变器并联得到广泛关注。但是,当逆变器共直流母线和共交流母线并联且不存在无隔离变压器时,在空间矢量调制中注入三次零序电压将产生零序环流。本文分析了空间矢量调制技术,研究了空间矢量调制,并研究了三次零序电压对零序环流的影响,然后提出一种改进的比例谐振方法抑制零序环流,该方法能够在电感和给定电流不相等的情况下适用。基于并联逆变器,通过仿真和实验验证了提出方法有效性。

The parallel inverters can increase system capacity, reduce system cost and improve system efficiency. Therefore, the parallel inverters are received widespread attention. However, a zero sequence circulating current ( ZSCC) is typically generated among the multi-parallel converters that share the common DC-link and the AC side without isolated transformers under the space-vector modulation (SVM), due to the injected third-order zero sequence voltage ( ZSV). This paper analyzes SVM techniques, studies the effects of the ZSV on the ZSCC control loop in detail, and then proposes an improved proportional resonance scheme to suppress the impact of the ZSV on the ZSCC. The proposed strategy can effectively realize the ZSCC suppression, even though the parallel converter modules have asymmetrical current references and filter inductances. The simulation and experimental results based on the parallel converters clearly verify the effectiveness of the proposed control.