光伏逆变系统中的ZVS升压变换器

ZVS boost converter of photovoltaic inverter system

针对两级式单相非隔离型光伏并网逆变器的前级电路,研究了一种新型的ZVS(zero voltage switch)Boost升压变换器电路拓扑。通过增加一个开关管、谐振电感、吸收电容及两个二极管组成辅助电路,实现了Boost升压变换器电路中主开关管及所增加的辅助开关管的零电压导通与关断,从而减小了系统的开关损耗。分析了ZVS Boost升压变换器电路拓扑的工作原理,探讨了谐振电感与谐振电容、吸收电容的定量关系及选择条件,对所研究的ZVS Boost电路拓扑进行了软件仿真与实验验证,结果表明该拓扑工作在开关频率为20 kHz、功率为2.5 kW时,所提出的两级式单相非隔离型光伏并网逆变器的整机效率可以达到97.16%。

For the pre-stage circuit of two-stage single-phase non-isolated photovohaic （PV） grid inverter, a zero voltage switching （ZVS） boost converter circuit topology, which is realized by adding a switch tube, a resonant inductor, a snubber capacitor and two diodes to form auxiliary circuit, is researched to achieve the ZVS of main switch tube and the auxiliary switch in the boost converter circuit, thus signifi- cantly reducing the switching losses. The operation mode of the proposed ZVS Boost converter circuit to- pology was analyzed. Then the quantitative relationship between the resonant inductor and resonant ca- pacitor as well as the absorption of the capacitance and the respective selection criteria was explored. The simulation and experimental validation of the researched circuit topology was completed, from which the experimental results show that the whole efficiency of the proposed two single-phase non-isolated PV grid inverter can achieve up to 97.16% on 20 kHz switching frequency and 2.5 kW.