适用于微电网的软开关型高效光伏并网微型逆变器

针对光伏并网小功率逆变器应用场合,提出一种能实现软开关的两级式微型逆变器,其前级采用有源箝位正反激变换器电路,通过箝位电路实现主开关管漏源极电压箝位,利用漏感电流为主开关管结电容放电实现零电压开通;后级采用基于临界电流连续控制的传统单相全桥逆变器,通过控制电感电流双向流动,实现开关管的零电压开通。搭建的250 W并网逆变器样机验证了所提方案的可行性和正确性。结果表明基于软开关控制方式的微型逆变器能大大提高效率,适用于微电网中光伏并网微型逆变器等功率较小的应用场合。

A High-efficiency PV Grid-tied Micro-inverter with Soft Switching in Micro-grid Application

A two-stage micro-inverter is proposed in this paper to achieve soft switching for PV grid-tied micro-inverter. The front-end stage of micro-inverter employs active-clamp forward-flyback converter which can clamp the drain-source voltage of main switch and achieve zero voltage switching(ZVS) by discharging the parasitic capacitor with the leak inductor current. While, the second stage is a traditional single-phase full-bridge based on boundary current mode(BCM) with a control strategy of controlling the inductor current bidirectional to achieve ZVS. A 250 W prototype is built to verify the validity of design. The results show that the soft switching controlled mode can hence improve the efficiency of micro-inverter, which is especially suitable for low power application such as micro-inverter in micro-grid.