模块化多电平换流器的载波层叠脉宽调制策略分析与改进  

Analysis and Improvement on Carrier Level-shifted Pulse Width Modulation Strategy for Modular Multilevel Converter

作　　者：白志红[1] 周玉虎 BAI Zhihong;ZHOU Yuhu(College of Electrical Engineering,Zhejiang University,Hangzhou 310027,China;Delta Hangzhou Design Center,Hangzhou 310051,China)

机构地区：[1]浙江大学电气工程学院,浙江省杭州市310027 [2]台达电子企业管理(上海)有限公司杭州分公司,浙江省杭州市310051

出　　处：《电力系统自动化》2018年第21期139-144,共6页Automation of Electric Power Systems

基　　金：国家自然科学基金资助项目(51877194);浙江省自然科学基金资助项目(Y16E070005)~~

摘　　要：采用载波层叠脉宽调制(PWM)策略时,模块化多电平换流器(MMC)的各子模块投入时间和开关频率差异大,导致各子模块直流侧电容电压出现严重不均衡以及开关管损耗和发热情况不一致,致使系统无法正常运行。文中在研究载波层叠PWM策略原理及其在MMC中应用问题的基础上,对其实现过程进行了改进,将多列载波按一定周期进行轮换以控制MMC各子模块。仿真结果表明,采用载波轮换层叠PWM策略后,各子模块平均投入时间以及开关管开关频率可达到一致,子模块电容电压即使没有采取专门闭环控制也可以实现平衡,从而系统整体控制算法得以简化。The sub-modules of modular multilevel converters（MMCs）have different operation time and switching frequency when the carrier level-shifted pulse width modulation（CLS-PWM）is adopted.As a result,the capacitor voltages of the submodules are seriously unbalanced and the loss and heating of the power switches is uneven as well,moreover,the system is not able to work normally with the CLS-PWM scheme.The principle of the traditional CLS-PWM is investigated and the inherent problems are identified,based on which,an improved CLS-PWM strategy is proposed for MMC based on the carrier rotation.Simulation results show the sub-module capacitor voltages can be balanced well even without particular control of each submodule capacitor voltage by using the proposed method and thus the overall control algorithm of the system is simplified.

关 键 词：模块化多电平换流器 载波层叠 脉宽调制 电容电压平衡 

分 类 号：TM46[电气工程—电器]