基于功率预测的光伏微逆变器低频电流纹波抑制策略

Power Prediction Based Reduction Strategy for Low-frequency Current Ripple of Photovoltaic Micro-inverter

随着单块光伏电池输出功率越来越高,以反激电路为基础的传统光伏微逆变器(PM)难以达到高效率,因此以桥式电路为基础的PM越来越受到重视。文中提出一种较小容值的桥式PM及其基于功率预测的输入侧低频电流纹波抑制方法。该方法取消了传统的电流内环,而且保证变换器的输出功率能够在一个开关周期时间内实现快速跟踪。考虑到实际参数与检测值的误差,所提功率预测方法仍具有很好的稳定性与鲁棒性。通过建立系统的小信号模型,设计了电压外环的调节器参数,使得电压环具有较大的带宽。实验结果证明了所提PM性能优良。

With the increase of output power of a single photovoltaic cell,the conventional photovoltaic micro-inverter (PM) based on simple flyback topology cannot realize high conversion efficiency.Thus,the micro-inverter based on full-bridge topology is getting more and more attention.This paper proposes a full-bridge micro-inverter with small filter capacitors.A control strategy using power predictive method is proposed,which can reduce the low-frequency current ripple.The current inner-loop is removed from the control strategy.The output power can track its reference value in a switching cycle.Taking into account the error between the actual parameters and the detected values,the proposed power prediction method still has steady and robust characteristics.The regulator parameters of the voltage-loop are designed according to the small-signal model,to guarantee a wide bandwidth of voltage-loop.The experimental results verify the good performance of the proposed PM.