级联多电平H桥逆变器的同相层叠型SPWM脉冲分配方法

提出一种适用于级联H桥逆变器的新型同相层叠(IPD)型正弦脉宽调制(SPWM)脉冲分配方法。根据多电平级联H桥的一般模型,分析了功率不平衡的产生原因,引入功率失衡度的概念,推导出新型IPD型SPWM脉冲分配原理。该方法将各H桥单元的触发信号进行周期轮换,经过3/4个输出周期便可实现功率平衡,而且保证了线电压的波形质量,具有比载波移相(CPS)法更低的总谐波畸变率。以7电平级联H桥逆变器为例,仿真和实验结果证明了所提新型IPD型SPWM脉冲分配方法的可行性以及理论分析的正确性。

Pulse distribution strategy for IPD-SPWM of cascaded multi-level H-bridge inverter

A strategy of pulse distribution for IPD(In-Phase Disposition)-SPWM(Sinusoidal Pulse Width Modulation) of CHB(Cascaded H-Bridge) inverter is presented. The cause of CHB power imbalance is analyzed based on its general structure and the concept of power imbalance degree is introduced to deduce the pulse distribution principle of IPD-SPWM, which cyclically changes the trigger signals of every CHB unit to realize the power balance of every 3/4 output cycle for ensuring the waveform quality of line voltage and lower THD (Total Harmonic Distortion) than CPS(Carrier Phase Shift) strategy. With seven-level three-unit CHB inverter as an example, the feasibility of the proposed pulse distribution strategy for IPD-SPWM and the correctness of theoretical analysis are verified by the simulative and experimental results.