级联型多电平逆变器最小总谐波失真阶梯调制策略研究.pdf

第42卷第19期
セ力系係护控剃
Vol 42 No I
2014年10月1日
Power System Protection and Control
Oct.1,2014
级联型多电平逆变器最小总谐波失真阶梯调制策略硏究
李素非,李国杰,瞿登辉2,王卫星2
(1.电力传输与功率变换控制教育部重点实验室,上海交通大学电气エ程系,上海20024
2.许继电气股份有限公司,河南许昌461000
摘要:为了降低級联型多电平遂变器的输出电压谐波分量,提出了一种新颖的基于KT条件最优化方法的阶梯调制策略。利
用KKT条件法,经过严格的数学推导,得到相应的导通角计算方法,所提出的阶梯调制策略能够在任意调制系数下最小化阶
梯波输出的总谐波失真(THD),另外利用牛顿一拉普逊代法来求取上述导通角计算中的关键参数。为了克服牛顿一拉普逊
迭代法计算速度熳的缺点,提出了幂函数逼近法来简化计算复杂度。最后,对上述方法进行了仿真分析,得到了固定和可变
调制系数下的级联逆变器输出电压波形和其频语分布。仿真结果证实了调制策略的有效性。
关键词:级联型多电平逆变器;总谐波失真;阶梯调制;KKT条件法;函数逼近
Staircase modulation strategy with minimum total harmonic distortion for cascaded multilevel
inverters
LI Su-fei, LI Guo-jie, ZHAI Deng-hui, WANG Wei-xing
(1. Key Laboratory of Control of Power Transmission and Conversion, Ministry of Education(Department of Electrical Engineering.
Shanghai Jiao Tong University Shanghai 200240, China; Xuji Electric Co, LTD, Xuchang 461000, China)
Abstract: In order to decrease the output-voltage harmonic components of cascaded multilevel inverter, this paper proposes a novel
staircase modulation strategy based on Karush-kuhn-tucker( KKT) conditions. With KKT conditions and rigorous mathematical
derivation, this paper acquires the corresponding calculation method of conducting angles, and the proposed staircase modulation
strategy can minimize the total harmonic is o tion(THD under arbitrary modulation index. Furthermore, this paper takes advan age
of Newton-raphson iteration method to obtain the key parameter in the aforementioned conducting angle calculation method. To
overcome the deficiency of slow calculation speed of Newton-raphson iteration method, this paper proposes the power function
approximation approach to simplify calculation complexity. Finally, this paper undertakes simulation analysis and obtains the outp
voltage waveforms and their frequency-domain distributions under both fixed and varying modulation indices. Simulation results
verify the effectiveness of the modulation strategy.
This work is supported by National Natural Science Foundation of China(No 51477098), National High Technology Research
and Development Program of China(63 Program)(No 201 A050212) and International S&T Cooperation Program of China (No
2013DFG71630)
Key words: cascaded multilevel inverter; THD; staircase modulation; KKT conditions; function approximation
中图分类号:TM464文献标识码:A
文章编号:1674-3415(2014)19-0008-10
0引言
器的调制分为高频调制和低频调制。常见的高频调
制策略有正弦载波调制(SPWM)?、特定谐波消
级联型逆变器在中/高功率等级的系统的中有除脉宽调制( SHEPWM)7空间电压矢量调制
广泛的应用。根据开关频率,可以将级联型逆变( SVPWM)。相对于高频调制策略而言,低频
阶梯调制能减小开关损耗和器件的开关应力,延长
基金项目:国家自然科学基金(51477098);国家高技术研究其使用寿命,提高系统效率。
发展计划863计划(2012AA050212);国家国际科技合作专项
在阶梯调制中,各电平导通角的计算是一个研
项目(2013DFG71630)
究热点。导通角讪算方法包括选择谐波消去法