基于VSVPWM的三电平中点电位补偿平衡控制

Novel Method on Neutral-point Potential Compensation Balancing Control Based on VSVPWM for Three-level Inverter

针对二极管钳位型(NPC)三电平逆变器存在着中点电位不平衡的问题,通过分析中点电位的波动机理,提出一种基于虚拟空间电压矢量调制(VSVPWM)的准确补偿中点电位的控制策略,引入虚拟中矢量和电压调整系数f,充分利用新的合成矢量对中点电位波动的平衡作用,根据中点电流的流向,对不同的正、负小矢量分配不同的调整系数;同时根据检测到的中点电位偏差,采用一种滞环控制的方法,在传统的基于k值的矢量调整控制和基于f值的准确补偿控制之间进行切换控制。仿真分析和实验结果表明,基于本方法的中点电位补偿控制策略,具有很好的中点电位平衡效果。

Since the neutral-point potential unbalance problem exsited in the NPC three-level inverter, the mechanism of the neutralpoint potential fluctation was analysed. A novel method on neutralpoint potential compensation balancing control based on virtual space vector pulse width modulation （VSVPWM） was proposed. A virtual medium vector and voltage adjustment factor fare introduced to take full advantage of the new synthetic vector＇ s control effect of neutral-point potential fluctuation, and different positive and negative short vectors were distributed different times according to the detected direction of neutral-point current, which the nutral-point potential control effect and its flexibility were improved. A hysteresis control method was adopted to use the traditional control based on voltage adjustment factor k and the accurate compensation control based on the voltage adjustment factorfrespectively according to the dectected neutral-point potential deviation.The simulation analysis and the experiment results show that the control strategy of neutral-point potential compensation based on VSVPWM has a good effect of neutral-point potential balance.