基于调制波分解的背靠背三电平变换器共模电压消除方法  

A Common-mode Voltage Elimination Method Based on Modulation Signal Decomposition for the Back-to-back Three-level Converter

作　　者：徐晓娜 王奎[1] 李永东[1] XU Xiaona;WANG Kui;LI Yongdong(State Key Laboratory of Control and Simulation of Power System and Generation Equipment(Department of Electrical Engineering,Tsinghua University),Haidian District,Beijing 100084,China)

机构地区：[1]电力系统及大型发电设备安全控制和仿真国家重点实验室(清华大学电机系),北京市海淀区100084

出　　处：《中国电机工程学报》2022年第8期2957-2968,共12页Proceedings of the CSEE

摘　　要：背靠背三电平中点钳位型(neutral-point clamped,NPC)变换器广泛应用于四象限交直交变频场合,其共模电压和中点电位平衡问题影响着系统的安全稳定运行。鉴于此,文中提出一种基于调制波分解的背靠背三电平NPC变换器的共模电压消除方法。首先,原始调制波被分解成两个虚拟参考调制波的差的形式;然后,将虚拟调制波与载波比较产生的虚拟脉宽调制(pulse width modulation,PWM)信号两两相减得到实际各相的PWM信号;最终可以实现共模电压完全消除。在此基础上,进一步采用零序电压注入方法来控制中点电位平衡。最后,通过实验验证所提出共模电压消除与中点电位平衡控制方法的有效性。Back-to-back three-level neutral-point clamped(NPC) converters are widely used in four-quadrant AC-DC-AC frequency conversion occasions. However, the common-mode voltage(CMV) and neutral-point potential(NPP) balance problems of back-to-back three-level converter affect the safe and stable operation of the system. A CMV elimination method based on the decomposition of the modulation signal was proposed for the back-to-back three-level converter. Each original reference modulation signal was divided into two virtual reference modulation signals. And the real PWM signals for each phase were obtained by the difference of two virtual PWM signals generated by comparing the virtual reference modulation signal with the triangle carriers. Then, the CMV was eliminated to zero by using this modulation method. On this basis, an optimized zero-sequence voltage injection method was adopted to control the NPP balance of the back-to-back three-level converter. Finally, experiments were carried out to verify the effectiveness of the proposed unified control method of CMV elimination and NPP balance.

关 键 词：背靠背三电平变换器 共模电压消除 中点电位平衡控制 调制波分解 

分 类 号：TM46[电气工程—电器]