三电平逆变器中点电位不平衡的谐波问题分析  

The Harmonic Analysis of NPC Three-level Inverter Under Unbalanced Neutral Point Voltage Condition

作　　者：马炜程 丁星星[1] 廖玉茗 皋艳[1] 

机构地区：[1]合肥工业大学,信息工程系,安徽宣城242000

出　　处：《电力电子技术》2017年第2期15-18,共4页Power Electronics

摘　　要：首先介绍了中点箝位型(NPC)三电平逆变器载波脉宽调制(CBPWM)策略,并建立一种同相层叠脉宽调制(PDPWM)策略在中点电位不平衡时等效的调制波数学模型,推导了各次谐波含量的计算公式。提出了一种不对称载波移位脉宽调制(ASPDPWM)策略,可以在中点电位偏移时输出正确的PWM序列,有效地抑制逆变器输出的低频谐波含量,并在此基础上改进了提高电压利用率的方法。在实验室搭建三电平仿真和实验平台,通过阻感性实验验证了ASPDPWM策略能够有效降低低频谐波以及谐波计算方法的可行性。Firstly, carrier-based pulse width modulation （CBPWM） strategy for the neutral point clamped （NPC） three- level are introduced.A mathematical model is established,which can equivalent to the modulated wave with carrier disposition PWM （PDPWM） when the neutral point voltage is unbalanced, and the calculation method is derived for each harmonic proportion.In the case of the neutral point voltage offset, an asymmetric carrier disposition PWM（ASPDPWM） strategy is proposed, which can output PWM sequence correctly and suppress low frequency harmonic content of the inverter output effectively.And on this basis, a method is proposed to improve the voltage utilization.A NPC three-level converter simulational and experimental platform are built in the laboratory.The effectiveness of the ASPDPWM strategy to reduce low-frequency harmonics and the calculation method of harmonics is verified with the resistive inductive load.

关 键 词：逆变器 谐波 中点箝位 

分 类 号：TM464[电气工程—电器]