三电平中点钳位电压型逆变器带不平衡负载时的复合控制策略  

Integrate Control Strategy for Three-level Neutral-point Clamped Voltage Source Inverter with Unbalanced Load

作　　者：肖飞[1,2] 谢桢[2] 吕昊[3] 

机构地区：[1]浙江大学电气工程学院,杭州310013 [2]海军工程大学舰船综合电力技术国防科技重点实验室,武汉430033 [3]海军装备研究院,北京100161

出　　处：《高电压技术》2013年第2期474-480,共7页High Voltage Engineering

基　　金：国家自然科学基金(50977090;51147009)~~

摘　　要：为了改善不平衡负载条件下三电平中点钳位型(NPC)电压型逆变器的输出电压波形,采用了延迟信号撤销法(DSC)分离出正序和负序电压分量分别进行控制。但此方法在修正了电压波形的同时,会进一步增加输出电流的不对称性,导致在空间矢量脉宽调制算法(SVPWM)下三电平NPC电压型逆变器中点电位的波动加剧。针对这个问题,计算了负序电流分量对中点电位波动的影响。结果显示随着负序不平衡度增加,中点电位等效控制能力有可能增大或者减小,主要取决于输出功率因素。而当调制比>0.5时,由于功率因数和负序不平衡因数不匹配,在该开关周期内无法对中点电位进行补偿。同时也找出了1个开关周期内控制冗余小矢量的作用时间对中点电位调整能力的边界,从而建立了中点电位控制的空间矢量调制算法。另外,提出了基于DSC算法对电压正负序分量进行分离,分别在正向负向旋转坐标系下进行电压控制,并结合中点电位控制的复合控制方案。仿真计算表明该控制方案下,负序电压分量在负方向旋转的坐标系下得到控制,同时负序电流作用使得中点电位的波动加剧,但是在空间矢量中点电位调制下,中点电压波动得到抑制。仿真结果验证了该复合控制策略下三电平中点钳位型电压型逆变器具有较好的带不平衡负载的能力。In order to improve the wave of voltage,a delay signal cancel（DSC） method has been used to distinguish and control the positive and negative sequence components.However,while reinforcing the voltage waveform,the method increases the imbalance of the current,which results in seriously neutral-point voltage oscillating,under the space vector pulse width modulation（SVPWM）.Thus,impact of the negative sequence current to neutral-point voltage oscillation is calculated.The results show that the neutral-point control ability could be increased or decreased with the negative sequence component increasing,which is mostly depended on the power factor.When the modulate proportion is bigger than 0.5,the neutral-point control ability can be descend to zero because of the inconsonance between the power factor and negative sequence gene.Moreover,the boundary of the ability to control the unbalance by controlling the redundant voltage small vectors is found.Therefore the neutral-point control SVPWM is built.Plus,a integrate control strategy for three-level neutral-point clamped（NPC） voltage source inverter with unbalanced load based on distinguishing and controlling the positive and negative sequence components by DSC is put forward.Simulation exhibit that by the presented method,the negative sequence voltage can be restrained,and the negative sequence current makes the neutral-point unbalanced,while the voltage fluctuation at the neutral-point is controlled by the integrate control strategy.It is proved that under the integrated control strategy,three-level NPC voltage source inverter（VSI） performs well with unbalance load.

关 键 词：三电平 电压型逆变器 空间矢量脉宽调制算法 不对称负载 中点电位 延迟信号撤销法 

分 类 号：TM464[电气工程—电器]