基于改进虚拟空间矢量调制方法的中点箝位型三电平逆变器电容电压平衡问题  

Capacitor potential balancing of neutral-point clamped three-level inverter based on improved virtual space vector PWM

作　　者：申张亮[1] 郑建勇[1] 梅军[1] 

机构地区：[1]东南大学电气工程学院,江苏南京210096

出　　处：《电力自动化设备》2011年第3期79-84,共6页Electric Power Automation Equipment

摘　　要：针对二极管箝位三电平逆变器在不同负载及调制比的条件下,传统的空间矢量调制方法中点电压存在不能平衡的区域,而利用虚拟空间矢量的调制方法,在输出三相电流之和为零时,即能实现对中点电压的完全控制,但需要进行大量的三角函数运算及扇区判断,增大了控制器的计算工作量和实现难度。提出一种改进的虚拟空间矢量调制方法。通过虚拟矢量空间尺度的放大,进一步减少小扇区的划分,简化计算。通过将虚拟空间矢量分解到60°坐标系,无需进行扇区判断以及大量三角函数的计算即可得到各桥臂开关管在每个开关周期内的开通时间,可在调制比≤2/3范围内实现中点电压平衡完全控制,同时在矢量选取和作用时间计算方面进行了简化。最后构建了二极管箝位三电平逆变器模型,对该方法在中点电压平衡控制上的有效性进行了验证。There is unbalanced area of neutral-point potential in traditional space vector PWM scheme for diode-clamped three-level inverters under different loads and modulation ratios.The virtual space vector PWM scheme,which may completely control the neutral-point potential when the sum of three phase output currents reaches zero,needs lots of trigonometric function calculations and sector judgment.An improved virtual space vector PWM scheme is presented.It enlarges the space scale of virtual vector to decrease the division of small sectors,thus simplifying the calculation.Since the virtual space vector is decomposes into 60° coordinates system,the turn-on time of each arm switch in every period is obtained without sector judgment and trigonometric function calculations,completely controlling the potential balancing within the range of modulation ratio less than 2 / 3.The vector selection and effect time calculation are also simplified.A model of three-level diode-clamped inverter is established to verify the effectiveness of the proposed PWM scheme.

关 键 词：三电平逆变器 虚拟空间矢量调制 60°坐标系 中点箝位型 

分 类 号：TM461[电气工程—电器]