基于恒最大化升压比Z源三电平中点钳位逆变器研究

三电平中点钳位逆变器由于具有低谐波和波形质量好而备受关注;然而为了实现光伏等分布式电源高电压,需要增加DC/DC才能实现升压和逆变功能,这降低了系统效率。为了解决上述问题,研究了Z源三电平中点钳位逆变器。传统的同相电压偏移(phase disposition,PD)的方法虽然能够减少开关次数和降低开关损耗,但是升压能力不够。提出一种恒最大化升压方法,能够在任何调制比情况下实现最大化的升压;而且能够消除低频纹波和减少电压应力的作用。详细地分析了升压比和开关频率之间的关系;并通过仿真和实验证明了所提算法方法的有效性。

Based on Constant Boost Control Z-Source Three-level NPC inverter

The neutral point clamping (NPC) inverter is popular for low harmonic and good quality waveform. In order to supply high voltage for the photovoltaic and other distributed power, it is needed to increase the DC/DC boost functions. However, the efficiency of system is decreased. In order to solve above problem, this paper research z-source (NPC) three-level inverter. The conventional phase disposition method can reduce switch frequency, lower switching loss. However, the boosting ability of this method is not enough. This paper proposes a constant boost-control method for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. The relationship of voltage gain to modulation index is analyzed in detail. The validity is proved by the simulation and experiment.