Z源变流器的谐波抑制及稳压控制

Harmonic elimination and voltage stabilization of Z-source converter

为保证敏感负载的高稳定电能供应,提出了一种应用于Z源AC/AC变流器的谐波抑制及稳压算法。通过输入电压基波量与整体量的实时比较产生的误差信号,生成占空比随时间变化的开关调制函数。通过开环方式,对变流器的输出开关占空比进行实时调节。和已有的恒定占空比控制相比,实现了对交流输入电压中低次谐波的有效抑制,并且不要求分别计算各谐波分量,简化了控制策略,同时显著降低了系统对控制器带宽的要求。通过PI闭环控制,将变流器输出电压实时稳定于基准值。概述了变流器的工作原理,分析和推导了谐波抑制调制函数的解析式,设计了PI环节,给出了总体控制方案。仿真表明该控制算法对交流系统侧谐波电压具有良好的抑制能力,同时保证精确稳定的电压输出。

An algorithm of harmonic elimination and voltage stabilization is proposed for Z-source AC/AC converter to ensure its stable power supply.A switching modulation function with varying duty factor is generated based on the difference between fundamental input voltage and whole input voltage.The output switching duty factor of converter is regulated by open-loop control in real time,which suppresses the low-order harmonics of AC input voltage more effectively than the constant duty cycle control.As the harmonic components are not calculated separately,the control scheme is thus simplified and the controller bandwidth relieved.The output voltage of converter is stabilized at the reference value by PI close-loop control.The operation principles of the converter and the realization of the proposed algorithm are discussed.Simulative results show its excellent performance in harmonic suppression and voltage stabilization.