基于动态空间矢量的三电平逆变器不连续调制策略

Discontinuous Modulation of Three-Level Inverter Based on Dynamic Space Vector

针对不连续调制策略下二极管钳位式三电平逆变器中点电位波动难以抑制的问题,提出一种动态空间矢量不连续调制策略。该策略通过实时检测逆变器上下电容电压,生成动态空间矢量,进而精确合成参考矢量,有效降低中点电位波动带来的输出波形畸变。采用基于gh坐标系及奇偶扇区转换的方法,避免空间矢量动态化带来的调制算法复杂度问题。为消除中点电位偏移,提出实时切换对中点电位具有相反作用的开关矢量序列的方法。最后给出基于误差电流矢量的调制策略评价方法,从理论上验证了所提的动态空间矢量调制的优势。仿真和实验结果进一步验证了本文所提方法的有效性。

Since the neutral point potential fluctuation of three-level inverter is difficult to suppress under discontinuous modulation strategy,a dynamic space vector strategy was proposed.This strategy could generate a dynamic space vector by real-time detecting the upper and lower capacitor voltages,and then accurately synthesize the reference vector.This paper adopted gh coordinate system and parity sector conversion method to reduce the complexity of the dynamics algorithm.In order to eliminate the neutral point potential offset,this paper also proposed a method of switching vector sequence with reverse effect on the neutral point potential in real time.Finally,the evaluation method of modulation strategy based on the error current vector was given,which verified the advantages of the dynamic space vector modulation.Simulation and experimental results further show the effectiveness of the proposed method.