全 MOSFET型全桥非隔离光伏并网逆变器

摘要

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 com-mon-voltage, the clamping technology is adopted to clamp common-voltage to a constant value.An improved invert-er topology and modulation strategy has been proposed, 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 re-verse 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.Finally, the performance of the proposed topology is verified by a prototype inverter rated at 3 kW and 50 kHz.%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SiC－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 kHz／3 kW实验样机对比验证了新型拓扑的性能。