基于60°坐标系的改进三电平逆变器中点电压调制策略

An Improved Neutral-Point Voltage Modulation Strategy Based on 60°Coordinate System for Three-Level Inverter

中点电压不平衡直接影响逆变器输出电压波形的质量以及器件的寿命。针对NPC型三电平逆变器中点电压不平衡问题,对传统的虚拟空间矢量调制方法进行改进,设计了一种改进的虚拟空间矢量脉冲宽度调制(improved virtual space vector pulse width modulation,IVSVPWM)方法。首先,定义了新的虚拟矢量,目的是降低共模电压幅值;然后,对扇区小三角形区域进行划分,计算了虚拟矢量的作用时间,设计了空间矢量的作用顺序;最后,在MATLAB/Simulink中搭建了仿真模型,对传统的虚拟空间矢量脉冲宽度调制(virtual space vector pulse width modulation,VSVPWM)方法和本文设计的IVSVPWM方法进行比较。结果表明本文设计的方法具有更好的中点电压平衡效果。

The neutral point voltage imbalance directly affects the quality of the inverter output voltage waveform and the lifetime of the device.Aiming at the problem of neutral point voltage imbalance in NPC type three-level inverters,we improved the traditional virtual space vector modulation method and designed an improved virtual space vector pulse width modulation(IVSVPWM)method.In our proposed method,first,a new virtual vector is defined to reduce the amplitude of common-mode voltage.Then,the small triangular area of the sector is divided,the action time of the virtual vector is calculated,and the action sequence of the space vector is designed.Finally,a simulation model is built in MATLAB/Simulink,and the traditional virtual space vector pulse width modulation(VSVPWM)method is compared with the IVSVPWM method designed in this article.The results show that our proposed method has better midpoint voltage balance effect.