基于SHEPWM的三电平三相逆变器中点电位主动平衡控制策略  

Active Neutral-Point Voltage Balance Control Strategy for Three-Level Three-Phase Inverter Under SHEPWM

作　　者：董志强 王琛琛[1] 周明磊[1] 刘明月 李凯[1] Dong Zhiqiang;Wang Chenchen;Zhou Minglei;Liu Mingyue;Li Kai(School of Electrical Engineering Beijing Jiaotong University,Beijing 100044 China)

机构地区：[1]北京交通大学电气工程学院,北京100044

出　　处：《电工技术学报》2024年第4期1147-1158,共12页Transactions of China Electrotechnical Society

基　　金：北京市自然科学基金资助项目(3222056)。

摘　　要：在大功率系统中,常采用特定次谐波消除脉宽调制(SHEPWM)以降低系统的开关损耗。针对三电平中点钳位(NPC)型三相逆变器在SHEPWM下的中点电位偏移问题,分析SHEPWM下逆变器输出相电压基波与3次谐波在不同电压相位范围内对中点电位的影响,设计两种在基波周期内对中点电位总充放电效果相反的开关角组合方案,并提出一种通过测量中点电位偏移值及中点电位滞环控制,选择不同的开关角组合方案进行调制的中点电位主动平衡控制策略。实验结果验证了所提出方法的实用性及有效性。In the high-power system,the three-level neutral-point clamped inverter needs to adopt SHEPWM to reduce the switching power loss.The traditional neutral-point potential active balance control strategy adjusts the duty cycle of the zero-level of phase voltage by superimposing a slight angle based on the switching angle of SHEPWM from the polarity of each phase load current and neutral-point potential shift.However,the small number of SHEPWM switching angles limits the neutral-point potential balance ability.The fewer the number of SHEPWM switching angles,the weaker the neutral-point potential balance ability.Therefore,this paper analyzes the influence of the fundamental wave and the third harmonic of the output phase voltage under SHEPWM on the neutral-point potential in a different range of voltage phase angles,designs two switching angle combination schemes with opposite effects on the neutral-point potential in the fundamental wave period,and proposes a method to control the neutral-point potential by selecting different switching angle combination scheme to modulate according to the offset value and the hysteresis of the neutral-point potential.The influence analysis of the fundamental wave and the third harmonic wave on the neutral-point current shows that the neutral-point current components generated by the fundamental wave and the third harmonic wave have triple frequency fluctuation.Moreover,when the amplitude of the third harmonic is 0.2636 times that of the fundamental wave,the integral of the neutral-point current components generated by the fundamental wave and the third harmonic cancels each other in the interval of the fundamental wave phase angle every 60 degrees.The neutral-point current integral in the whole fundamental wave cycle can be adjusted by setting the third harmonic content at every 60 degrees of the fundamental wave phase angle to control the neutral-point potential.Therefore,two switching angle combination schemes are proposed,with opposite effects on the neutral-point potential and n

关 键 词：三电平中点钳位型逆变器 中点电位控制 特定谐波消除脉宽调制 3次谐波 

分 类 号：TM464[电气工程—电器]