提出了一种新型三电平中点箝位(NPC)变流器双调制波载波调制策略。研究了新策略调制波与传统正弦脉宽调制(SPWM)策略调制波的关系,在尽可能减小系统开关频率的前提下推导了新策略调制波的解,并对新策略的直流电压利用率、器件开关频率和输出相电压总谐波畸变率(THD)等特性进行了深入研究,最后进行了实验验证。与传统三电平SPWM策略相比,虽然新型双调制波载波调制策略功率器件开关频率较高,但该策略在任意调制度和任意功率因数下均可保持直流电容电压的平衡,且具有简单易行、易于数字化实现的优点。
A novel double modulation wave carrier-based strategy of neutral point clamping(NPC)three-level converter is proposed.The relations of the new strategy and traditional sinusoidal pulse width modulation(SPWM)strategy is analyzed.The analysis of the DC voltage utilization ratio,the device switch frequency and the output phase voltage total harmonic distortion(THD)characteristics are analyzed.Compared with the traditional three-level SPWM,the new strategy can keep the capacitor voltage balance in any modulation degree and power factor and has the advantages of simple and easy to realized.