单相光伏并网逆变器输入电流波动问题研究

Research on the Fluctuation of Panels Input Current of Single-phase Photovoltaic Grid-connected Inverter

单相光伏逆变并网功率电路采用两级形式,前级Boost电路升压,后级全桥逆变完成直流到交流的转换。该拓扑由于输出功率为交流,输入功率为固定值,使系统在功率传递过程中存在波动,从而导致输入电流波动。对功率传递过程进行了详细分析,对母线电容电压存在的波动以及这种波动对输入电流的影响进行了理论推导,并且根据其特点,提出了分段控制校正算法,最后通过3 kW样机实验验证了解决方案的可行性,并且给出了相应波形。

The power circuit of the single-phase PV inverter uses two-class form, the former class is to rise voltage, the post-class adopts full-bridge inverter to fulfill the change of DC/AC.Because the output power is AC,and the in- put power is a fixed-value, this topology will lead to the fluctuation of the input current.The power transfer process is analyzed meticulously, a theoretical derivation to voltage fluctuations of the generatrix capacitor and the impact of such fluctuations on the input current is given, and according to its characteristics, the corresponding correction con- trol algorithm of subdivision control is raised.The feasibility of the solution is verified through the 3 kW experimental prototype, and the corresponding waveform is given.