基于PI控制的飞跨电容均压环研究

Research on Flying Capacitor Voltage Balance Based on PI Control

光伏发电占我国发电总量的比重越来越大。飞跨电容多电平拓扑能够有效减小电感体积,因此在高功率密度、高效的场合具有应用前景。但飞跨电容逆变器实际运行中,会出现飞跨电容电压不均压的情况,不仅会使电路失去倍频效应,还会使开关管两端的电压应力不均衡,造成损坏。选择七电平FCML作为实验对象,将基于PI控制的均压环拓宽至七电平FCML中,搭建了一台3kW的样机验证了基于PI控制的均压环均压效果的有效性。

With the development of new energy,the output of photovoltaic power generation accounts for an increasing proportion of China's total output of power generation.As an indispensable part of photovoltaic power generation,photovoltaic inverter is often required to have high power density and high efficiency due to the limitation of site and other factors.Flying capacitor(FCML)multilevel topology can effectively reduce the volume of inductance,so it has a great prospect in the situation of high power density and high efficiency.However,during the actual operation of the flying capacitor inverter,the voltage of the flying capacitor is often uneven.The uneven voltage of the flying capacitor will not only make the circuit lose the"frequency multiplication"effect,but also make the voltage stress at both ends of the switch tube unbalanced,resulting in the phenomenon of aircraft explosion.Therefore,this paper selects 7-level FCML as the experimental object,expands the grading ring based on PI control to 7-level FCML,and finally builds a 3kW prototype to verify the effectiveness of the grading ring based on PI control.