模块化多电平高压变频技术研究综述

摘要

模块化多电平换流器(MMC)作为一种新型高压大功率拓扑结构,不仅在直流输电领域中获得广泛关注,也在高压变频领域颇具应用前景.与传统的高压变频器拓扑相比较,模块化多电平换流器在灵活性、可靠性、电压波形质量、输入变压器设计、电压功率等级等方面均展现出一系列技术优势.为促进中国高压变频技术的发展,对MMC变频器的电路特点、子模块结构、调制方法、电容电压平衡策略、谐波分析、环流抑制、启动预充电、故障容错与可靠性、低频运行等方面的最新研究进展进行详细分析评述,并指出模块化多电平高压变频技术的研究难点与挑战.%As a novel high-voltage high-power topology, modular multilevel converter (MMC) is not only widely concerned in the field of HVDC, but also in the field of motor drive applications. Compared with traditional medium-voltage motor drive topologies, MMC presents a series of distinctive features, such as high flexibility, high reliability, high voltage quality, easy input transformer design, high available voltage and power capacity. To popularize this new motor drive topology, this paper introduces its circuit characteristics, sub-module structure, modulation, capacitor voltage balancing, harmonic analysis, circulating current suppression, start-up precharge, fault tolerance, reliability and low-frequency operation. The state-of-the-art methods are evaluated. Finally, the existing difficulties and challenges of the MMC motor drive technology are discussed.