五开关H桥逆变器改进PWM控制方法的研究

Improved PWM Control Method for Five-switch H-bridge Inverter

针对传统级联五电平逆变器所需开关器件较多的问题,介绍了一种由1个辅助开关电路与H桥电路相结合的五开关H桥逆变器拓扑。根据该拓扑工作原理的特点,对其脉宽调制PWM策略进行了研究,提出了一种基于载波移相脉宽调制的改进型PWM控制方法。该方法依据两单元H桥级联,通过单极倍频CPS-PWM方法得到五电平相电压的波形,并把该五电平电压波形作为五开关H桥逆变器的输出目标波形,再结合逆变器的4种工作模式来逆向推导出PWM脉冲信号。最后通过仿真和实验研究证明了该拓扑结构和控制方法的可行性与有效性。

To solve the problem that the traditional cascaded five-level inverter requires many switching devices,a five-switch H-bridge inverter topology,which combines an auxiliary switching circuit with an H-bridge circuit,is introduced in this paper.According to the characteristics of the working principle for this topology,its pulse width modulation(PWM)strategy is studied,and an improved PWM control method based on carrier phase-shift PWM is proposed.Based on the two-cell H-bridge cascade,the waveforms of five-level phase voltage are obtained by the unipolar frequency doubling CPS-PWM modulation method,and the five-level voltage waveforms are taken as the output target waveforms of the five-switch H-bridge inverter.In addition,the PWM pulse signals are inversely derived with the combination of the inverter’s four operating modes.Finally,the feasibility and validity of this topology and its control method were proved by simulation and experimental results.