全MOSFET型全桥非隔离光伏并网逆变器

带交流旁路环节的非隔离型单极性SPWM全桥光伏并网逆变器可以在不增加导通损耗的前提下改善共模特性。为了进一步消除共模电压引起的漏电流,可以采用箝位技术实现高频共模电压为恒值。提出一种改进型全桥电路结构和调制方式,在续流模态提供了交流旁路环节和二极管无源箝位,避免了有源箝位支路的死区对箝位效果的影响。在桥臂和续流回路中采用Si C-MOSFET器件可消除桥臂二极管反向恢复问题和降低电流回路阻抗,可以大幅提高变换效率。详细分析了新型逆变器结构和准单极性SPWM调制的差模和共模特性,并通过一台50 k Hz/3 k W实验样机对比验证了新型拓扑的性能。

A Full Bridge Transformerless Photovoltaic Grid-Connected Inverter with All MOSFET

The transformerlsee photovoltaic (PV) unipolar SPWM full-bridge inverter with ac bypass brings low conduction loss and improves common-mode performance. In order to eliminate leakage current induced by common-voltage, the clamping technology is adopted to clamp common-voltage to a constant value. An improved inverter topology and modulation strategy has been proposed in this paper, two independence freewheeling paths and two diodes are added into the ac side of full bridge inverter. And then, the SiC-IGBT is adopted in the inverter to eliminate the reverse recovery problem. As a result, the efficiency can be significantly improved. The operation mode, differential-mode and common-mode characteristics of the proposed inverter are analyzed in detail in this paper. Finally, the performance of the proposed topology is verified by a prototype inverter rated at 3kW and 50kHz.