中点钳位型三电平逆变器基于调制波分解的调制策略  

A Modulation Strategy Based on Modulation Wave Decomposition for Neutral Point Clamped Three-Level Inverter

作　　者：王金平[1] 刘斌 董浩 姜卫东[1] Wang Jinping;Liu Bin;Dong Hao;Jiang Weidong(School of Electrical Engineering and Automation Hefei University of Technology,Hefei 230009,China)

机构地区：[1]合肥工业大学电气与自动化工程学院,合肥230009

出　　处：《电工技术学报》2023年第12期3221-3233,共13页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金面上资助项目(52077050)。

摘　　要：对于中点钳位型三电平逆变器(NPC TLI),一般通过单调制波与双载波相比较的方式产生脉冲序列,即基于载波的脉宽调制(CBPWM)。然而,该方法在高调制度低功率因数条件下中点电位(NPV)会出现三倍频波动。针对此问题,该文介绍一种简便的调制波分解方法,并以无条件实现NPV平衡的虚拟空间矢量脉宽调制(VSVPWM)为例说明该方法的可行性。在此基础上,提出一种可同时实现NPV平衡和开关损耗降低的调制策略。该调制策略具有四种模式,因此,将其命名为FM_VSVPWM。此外,对比了FM_VSVPWM与CBPWM、VSVPWM的调制性能。最后,通过实验验证了FM_VSVPWM的有效性和优越性。Compared with the two-level inverter,the neutral point clamped three-level inverter(NPC TLI)has the advantages of low electromagnetic interference,low voltage stress of switching devices,and low total harmonic distortion(THD).Therefore,it is widely used in renewable energy generation,the transmission of high voltage and high power,medium/high voltage variable frequency motor drives,and so on.Carrier-based pulse width modulation(CBPWM)method and space vector pulse width modulation(SVPWM)method are usually applied to NPC TLI,which are equivalent to a certain extent.CBPWM generates PWM sequences by comparing double carriers and single modulation waves.In this paper,the carrier of CBPWM is optimized by replacing double carriers with a single carrier.Then,the modulation wave is processed to eliminate the negative value.Accordingly,this paper proposes a modulation wave decomposition method and applies it to virtual space vector pulse width modulation(VSVPWM).The neutral point voltage(NPV)can still be unconditionally balanced under VSVPWM with this method,which proves the feasibility of the method.Compared with CBPWM,the switching loss is increased when VSVPWM is used,even though NPV can be unconditionally balanced,which greatly affects the power conversion efficiency of the inverter.Six modulation waves can be obtained when VSVPWM with the proposed method of modulation wave decomposition is used,and two of them are clamped.Limiting the modulation wave that is not clamped reduces the switching action of a specific phase and the switching loss.Four modes can be obtained after the modulation waves are limited,so this method is named FM_VSVPWM in this paper.Compared with VSVPWM,when the proposed FM_VSVPWM is used,the switching loss can be effectively reduced,and NPV can also be balanced in the full range of modulation index and power factor.The steady-state experimental results show that when the modulation index is 0.9,and the power factor is 0.26.NPV fluctuates with triple fundamental frequency,and the fluctuation amplit

关 键 词：中点钳位型三电平逆变器 调制波分解 中点电位平衡 开关损耗 调制策略 

分 类 号：TM464[电气工程—电器]