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一种适用三电平并联系统的虚拟矢量调制策略

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直流侧中点电位平衡和零序环流抑制是保证三电平逆变器并联系统正常运行的重要问题,然而基于冗余小矢量对调节的环流抑制方案进一步增加空间矢量脉宽调制(space vector pulse width modulation,SVPWM)中点电流无法对称消除的场景,加剧双机系统中点电位不平衡程度.该文基于虚拟矢量合成思路,提出一种满足零序环流抑制和中点电位平衡需求的双机虚拟矢量调制方法.该方法重新定义虚拟中矢量,通过缩短中矢量作用时间和增加参与合成的对称冗余小矢量以减少中点电流不平衡场景;分析不同扇区不同控制目标下虚拟矢量合成规则,利用相占空比法优化虚拟矢量的作用顺序,减少矢量合成过程中的开关次数.与传统SVPWM策略下中点电压变化量的对比分析表明,所提方法能够削弱环流抑制和中点电位平衡的耦合关系.最后,利用Starsim平台实验验证该策略的有效性.
A Virtual Vector Modulation Strategy for Paralleled Three-level Inverters
DC-side neutral-point(NP)potential balancing and zero-sequence circulating currents(ZSCCs)suppression are key to ensure the operation of the paralleled three-level inverters(PTLIs).However,the ZSCCs suppression scheme based on redundant small vector pair adjustment further increases the scenario where the currents entering and exiting the NP of space vector pulse width modulation(SVPWM)cannot be symmetrically eliminated,which aggravates the NP potential imbalance of the PTLIs.In this paper,based on the idea of virtual vector synthesis,we propose a PTLIs virtual vector modulation method that satisfies the requirements of ZSCCs suppression and NP potential balancing.The method redefines the virtual middle vector,reduces the NP current imbalance scenario by shortening the middle vector action time and increasing the symmetric redundant small vectors involved in the synthesis;analyzes the virtual vector synthesis rules under different control objectives in its different sectors,optimizes the action order of the virtual vectors by using the phase duty ratio method,and reduces the number of switches in the vector synthesis process.The comparative analysis of the NP voltage variation with the traditional SVPWM strategy shows that the proposed method can weaken the coupling relationship between the ZSCCs suppression and the NP potential balance.Finally,the effectiveness of the strategy is experimentally verified using the Starsim platform.

paralleled three-level invertersvirtual space vectorzero sequence circulation currentsneutral-point potential balancephase duty cycle methodthe number of switches

杜燕、杨世友、胡军龙、杨向真、苏建徽

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合肥工业大学电气与自动化工程学院,安徽省 合肥市 230009

教育部光伏系统工程研究中心,安徽省 合肥市 230009

三电平并联系统 虚拟矢量 零序环流 中点电位平衡 相占空比法 开关次数

国家重点研发计划项目中央高校基本科研业务费专项项目

2021YFB2601403PA2022GDGP0032

2024

10.13334/j.0258-8013.pcsee.231131

中国电机工程学报
中国电机工程学会

中国电机工程学报

CSTPCD北大核心
影响因子：2.712
ISSN：0258-8013
年,卷(期)：2024.44(21)