一种无漏电流非隔离光伏并网逆变器研究

Research on a Leakage-free Non-isolated Photovoltaic Grid-connected Inverters

由于效率高、体积小、重量轻和成本低,非隔离逆变器一直是国内外学者研究的重点,但非隔离逆变器易产生漏电流,从而带来安全问题。为此将常规两级式光伏并网逆变器后级全桥逆变中的一个桥臂替换为双向Buck-Boost电路,使光伏电池负极与交流侧中性点直接相连,光伏电池对地寄生电容被完全短路,以消除逆变器漏电流。文章对该改进型两级式光伏并网逆变器的工作原理进行了分析,提出了一种通过控制双向Buck-Boost电路的支路电流消除直流母线电容工频纹波的方法。最后通过仿真分析验证了该改进型光伏并网逆变器的可行性。

Due to high efficiency,small size,light weight,and low cost,non-isolated inverters have always been the focus of scholars at home and abroad,but non-isolated inverters are prone to generate leakage current,which brings safety problems.Therefore,one bridge arm of the rear full-bridge of the conventional two-stage inverter was replaced with a bidirectional Buck-Boost circuit,and the negative pole of the photovoltaic array was directly connected to the neutral point on the AC side in the inverter.So,the parasitic capacitance of the photovoltaic array to ground was short-circuited to completely eliminate leakage current.The working principle of the improved two-stage photovoltaic grid-connected inverter was analyzed,and a method to eliminate the power frequency ripple of the DC bus capacitor by controlling the branch current of the bidirectional Buck-Boost circuit was proposed.Finally,the feasibility of the proposed inverter topology was verified by MATLAB/Simulink simulation.