基于SPWM的Z源三电平逆变器升压与中点平衡控制

Boost and Neutral-point Balance Control of Z-source Threelevel Inverter Based on SPWM

Z源三电平逆变器通过注入直通状态可实现Z源三电平逆变器升压功能,但现有文献并没有考虑中点电位不平衡问题。为此,提出一种基于SPWM的方法来实现Z源三电平升压和中点平衡控制。首先通过注入直通状态实现升压控制,然后在此基础上,通过增加前馈改变直通占空比的方法实现了中点平衡控制。该方法不会增加Z源T型三电平逆变器的开关损耗,仿真和实验验证了所提方法的正确性。

Through inserting the shoot-through state,a Z-source three-level inverter can realize the function of boost control.However,the problem of unbalanced neutral-point voltage is not taken into account in the existing literature.To solve this problem,an SPWM method is proposed to realize the boost and neutral-point balance control of the Z-source three-level inverter.First,the DC-link voltage is boosted by inserting the shoot-through state.On this basis,feed-forward is added to adjust the shoot-through duty cycle to realize the neutral-point balance control.This strategy does not increase the switching loss of the Z-source T-type three-level inverter.The validity of the proposed method was proved by simulation and experimental results.