新型H6拓扑无隔离单相光伏并网逆变器研究

与带隔离变压器相比,无隔离变压器的光伏并网逆变器成本低、体积小、效率高,但无隔离光伏并网系统的漏电流将影响系统的安全运行,必须进行有效抑制,同时逆变器应具有向电网提供无功功率的能力。对此提出了一种新型的H6拓扑单相并网逆变器,该拓扑能有效抑制漏电流,且能向电网输出无功功率,采用单极性调制策略,输出电压具有三电平特性。基于对拓扑结构、工作过程及无功功率控制的详细分析,建立了Matlab/Simulink仿真模型验证理论分析的正确性,并搭建了1kW的实验平台,对理论分析和仿真结果进行了试验验证。

An Improved H6 Type Non isolation Grid connected PV Inverter

Compared with isolated transformer, inverter with non isolation transformer for grid connected PV has advantages of lower cost, smaller volume and higher efficiency, but its leakage current has impact on the safe operation of the system and needs to be suppressed effectively. In addition, the inverter should be capable of handling a certain amount of reactive power. In this study, a new H6 type single phase inverter for grid connected PV system is proposed, which can eliminate the threat of leakage current. The proposed topology has also the capability to inject reactive power into the power grid. Three level output voltage of the proposed topology can be achieved by using unipolar modulation. The topology structure, operation principle and reactive power control are investigated in detail. The proposed topology is simulated in Matlab/Simulink software to verify the accuracy of theoretical explanations. Finally, a universal prototype rated 1 kW has been built. The experiment validates the theoretical analysis and simulation results.