非隔离型三相FB7光伏逆变器研究

Research on Transformerless Three Phase Full Bridge FB7 PV Inverter

共模电流抑制是非隔离型光伏并网系统需要解决的关键问题之一。针对传统三相FB6光伏逆变器在共模电流抑制方面存在的问题,该文提出新型三相FB7光伏逆变器,并分析了其工作原理。根据系统共模电压和开关状态之间的逻辑关系,提出基于布尔逻辑运算的新型调制策略。该调制策略实现单极性输出线电压的同时,有效地减小了系统共模电流。最后搭建了TMS320F28335 DSP+XC3S400 FPGA数字控制硬件实验平台,对提出的方案进行了实验研究,并和传统三相FB6拓扑共模电流抑制方案进行了对比分析,实验结果验证了提出方案的有效性。

Common mode current suppression is one of the key issues in transformerless PV grid-connected systems. According to the problem of common mode current suppression in conventional three-phase PV inverter, a novel three-phase circuit named FB7 PV inverter was proposed, working principle was analyzed as well. A new carrier-based method based on Boolean function was proposed according to the relationship between common mode voltage and switching states. This new method could achieve unipolar output line voltage as well as reduce common mode current. Finally, the proposed modulation was carried out in the TMS320F 28335DSP ＋ XC3S400FPGA digital control platform, and then the results were compared with three-phase FB6 inverter. The experiment tests are conducted to verify the effectiveness of the proposed topology and modulation strategy.