摘要
模块化多电平变换器(modular multilevel converter,MMC)工作于低频工况时,子模块电容电压波动加剧导致输出电压畸变严重,制约了其在中高压大功率变频调速领域中的应用。针对这一问题,在分析MMC数学模型的基础上,从维持各相上、下桥臂功率动态平衡角度出发,设计一种基于注入高频共模电压及高频环流的电压波动抑制策略。为降低功率器件开关频率并减少系统损耗,将载波移相技术应用于MMC变频驱动,分别讨论输出N+1和2N+1电平相电压的实现方式。基于载波移相调制,结合低频工况子模块电容电压波动抑制方法,提出一种变频工况下MMC子模块电容电压控制策略,并设计相应控制系统架构及实现方式。该控制策略能在变频工况维持子模块电容电压平衡,保证调速过程中MMC和电动机正常平稳运行,并在低开关频率下获得良好的输出谐波特性。最后,通过搭建Matlab/Simulink仿真及实验样机,验证所提控制策略的正确性和有效性。
Applying the modular multilevel converter （MMC） into medium-voltage/high-voltage high-power drive systems is an intrinsically challenging problem because the output voltage distortion is serious when the converter works at low frequency operation, as a result of the sub-module capacitor voltages fluctuations＇ aggravation. For this matter, a method of injecting the high frequency common mode voltages and the circulating currents was designed from the perspective of balancing the upper and lower ann powers dynamically based on the analysis of the mathematical model of a MMC. The carrier phase-shift technology was adopted in the drive system to reduce the switching frequency and losses. The implementations to make the phase voltage as N＋I and 2N＋l levels were discussed. By combining the carrier phase-shift modulation and low frequency operation sub-module capacitor voltage restraining method, a voltage control strategy along with its system architecture and implementation were presented for variable frequency operation. The proposed control strategy achieves the goal of balancing voltages in variable frequency operation and makes the MMC and motor work stably. At the same time, a satisfied output harmonic characteristic is acquired at low switching frequency. Finally, the constructed Matlab/Simulink simulation and experimental prototype verify the availability of the proposed control strategy at variable frequency operation.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2015年第11期2822-2830,共9页
Proceedings of the CSEE
基金
国家自然科学基金项目(51377160)
江苏省普通高校研究生科研创新计划项目(KYLX_1384)~~
关键词
模块化多电平变换器
载波移相
变频
电压平衡
低开关频率
modular multilevel converter （MMC）
carrier phase-shift
variable frequency
voltage balancing
lowswitching frequency
作者简介
公铮（1990），男，博士研究生，研究方l向为多电平变换器控制技术及其应用，gzcumt@163．com
伍小杰（1966），男，教授，博士生导师，主要从事电力电子与电力传动、电机控制与保护等方面的研究开发和教学工作；
王钊（1989），男，硕士研究生，研究方向为电力电子与电力传动；
戴鹏（1973），男，教授，硕士生导师，主要从事电力电子与电力传动方面的研究开发和教学工作。
