基于SPWM的Z源T型三电平逆变器中点平衡和升压控制

Neutral point balance and boost control of Z-source T-type three-level inverter based on SPWM

由于Z源三电平中点钳位(NPC)逆变器存在无源器件多的缺点,采用Z源T型三电平逆变器拓扑,该拓扑具有Z源NPC逆变器相同的升压特性,但是开关器件数目较少,效率高。以电压源型Z源三电平T型逆变器为例,对同相电压偏移(PD)和反相电压偏移(APOD)方法进行分析,研究发现采用PD的方法可以减少开关次数,降低开关损耗。在Matlab/Simulink下,建立Z源T型三电平逆变器PD模型,仿真结果表明,采用PD方法能够获得较好的波形质量,并针对T型三电平逆变器固有的中点不平衡,提出了注入零序分量实现中点平衡控制。通过实验验证了所提方法的有效性。

The Z-source three-level neutral point clamped （NPC） inverter has the disadvantage of more passive compo- nents. The topology of Z-source T-type three-level inverter is adopted, which has the same boost characteristics with Z-source NPC inverter, but has less quantity of switching devices and higher efficiency than those of Z-source NPC inverter. Taking Z- source three-level T-type inverter as an example, the methods of phase disposition （PD） and alternative phase opposition disposi- tion （APOD） are analyzed. The study found that the PD method can reduce the switching frequency and switching loss. The PD model of Z-source T-type three-level inverter was established with Matlab/Simulink. The simulation results show that the PD method can obtain preferable waveform quality. To solve the inherent neutral point imbalance of T-type three-level inverter, the method of injecting zero-sequence component to control the neutral point balance is put forward. The effectiveness of the pro- posed method was verified with an experiment.