混合级联逆变器的混合频率载波调制技术  

Hybrid Frequency Carrier Modulation Technique for Hybrid Inverter

作　　者：苏利捷[1] 常恒宙 杨广德[1] 朱美丽[1] 黄保栋 

机构地区：[1]兰州交通大学自动化与电气工程学院,兰州730070

出　　处：《高电压技术》2017年第1期30-37,共8页High Voltage Engineering

基　　金：兰州交通大学科研项目(42016275)~~

摘　　要：混合频率载波调制法可以解决混合级联7电平逆变器的功率环流问题,但其输出电压的谐波特性较差。为此,提出了一种改进的混合频率载波调制策略,该策略使得高压单元运行在单极倍频正弦脉宽调制(sinusoidal pulse width modulation,SPWM)下,从而提高了高压单元的等效开关频率。此外,对高、低压单元的开关策略进行了优化改进,减少了开关次数。相比于改进前的方法,在高压单元开关频率相同时,其等效开关频率可提高1倍,逆变器输出电压的谐波将分布在更高的频段,从而改善了逆变器输出的电能质量,同时消除了功率环流。由仿真结果可知,在相同开关频率下,改进后的方法使得输出电压的较低次谐波由约1 k Hz提高到了约2 k Hz,并且不会出现功率环流现象。研究结果对所提出的改进的混合频率或波调制策略的实用化有一定意义。The hybrid seven-level inverter can run without power circulation in the presence of the hybrid frequency car- rier modulation, however, the harmonic characteristics of its output voltage is not ideal. According to the characteristic of the hybrid seven-level inverter, we propose an improved hybrid frequency carrier modulation strategy, which makes the high voltage cell run in monopole multiplier sinusoidal pulse width modulation （SPWM）, and improves the equivalent switching frequency of the high voltage cell. In addition, the switching strategies of the high- and low-voltage cell are op- timized in order to reduce the switching times. Compared to the former method, when the switching frequency of the high voltage cell is the same, its equivalent switching frequency can be doubled, and the harmonic of the output voltage will distribute in the higher frequency segment. This method can improve the power quality of the inverter, and eliminate the power circulation simultaneously. The simulation results show that, under the same switching frequency, the improved method makes the lower harmonics of the inverter output voltage from 1 kHz to 2 kHz nearby, and the phenomenon of power circulation does not appear. As a result, the method has a certain significance to the practical application of the im- proved hybrid frequency camer modulation strategy proposed in this paper.

关 键 词：单极倍频SPWM 混合级联逆变器 混合频率载波调制 混合调制 功率环流 总谐波畸变率 

分 类 号：TM464[电气工程—电器]