中文摘要：

提出了一种用于控制三电平ANPC逆变器中点电压平衡的改进式虚拟空间矢量调制（VSVPWM）方法，该方法使用与传统VSVPWM调制方法一样的基本矢量参与合成虚拟小矢量和虚拟中矢量，并根据采样得到的中点电压偏移情况以及三相电流的大小。在低调制度时，重新计算合成虚拟小矢量的正负小矢量的分配系数；在调制度较高时，重新选择产生不同中点电流的改进式虚拟中矢量，从而达到动态调节中点电压平衡的目的。此方法增强了中点电压平衡的控制效果，且实现了对整个矢量空间范围内中点电压的控制。最后，通过仿真和实验验证了所提出的控制策略的有效性。

英文摘要：

An improved virtual space vector PWM(VSVPWM)strategy was proposed to balance the neutralpoint potential(NP)forthree-levelactiveneutral-point-clamped(ANPC)inverter.Theimprovedvirtualvectors′synthesis method was based on the VSVPWM strategy.According to the NP offset and three-phase currents,when the modulation index was lower,the partition coefficient of a pair of short vectors could be recalculated,and when the modulation index was high,the appropriate improved virtual medium vectors which produce different neutral point current could be reselected in the next fundamental period.Therefore,the NP could be controlled effectively.This strategy can balance the NP wherever the reference vector locates in the space vector diagram(SVD).Lastly,simulation and experimental results are provided to verify the effectiveness of the proposed control strategy.