高压变频器共模电压仿真研究

该文分析了PWM高压变频器中输出电缆对电机影响、共模电压和三电平逆变器箝位点电位不平衡机理。为有效抑制共模电压对变频器的不良影响，提出了新型拓扑结构：在24脉波整流/三电平逆变的高压变频器中，设置共模电抗器，并将整流器中性点、直流侧中间点、输出滤波器中性点和三电平逆变器箝位点相连，并通过小电阻和系统地相连。基于该拓扑结构对6kV／2250kW的电机所进行的仿真结果表明，该拓扑结构可以减小高压变频器的共模电压，提高变频器运行的可靠性。

STUDY OF THE COMMON-MODE VOLTAGE IN A HIGH-VOLTAGE ASD'S SYSTEM

The principle of the influence of a long output cable, the common-mode voltage in a PWM high-voltage adjustable speed drive (ASD) system and imbalanced potential of the clamp point of a three-level inverter have been analyzed respectively. In order to effectively eliminate the adverse impact of the common-mode voltage on the ASDs, a new topology has been proposed including 24-pulse rectifier, common-mode reactor (CMR), three-level inverter and typical output 3-phase LC filter. In the topology, neutral points of both the rectifier and the dc-link,the star point of the output filter, and the neutral clamped point of the three-level inverter are connected together and merged into the ASDs grounding via a low resistance. Based on the simulation results of the proposed topology of a 2250kW/6kV motor, it can be concluded that the proposed topology can effectively give a high performance to eliminate the common-mode voltage, and improve reliability of the inverter in its operation.