混合五开关五电平光伏并网逆变系统研究

Investigation on Hybrid Five-switch and Five-level Grid-connected PV Inverter System

介绍了一种用于光伏并网系统的单相混合五开关五电平逆变器。该逆变器包含了1个全桥逆变电路及由4个二极管和1个开关组成的辅助电路,加入的辅助电路使得传统的三电平全桥逆变电路的输出变为五电平。分析了五开关五电平逆变器的工作过程,采用1个参考信号交替与2个载波信号进行比较的SPWM控制策略,获得了5个开关的开关信号。通过仿真对该逆变器的可行性进行了验证,逆变器输出电压和电流的谐波畸变率低,且并网电流与电网电压同频同相,满足并网要求。

A single-phase hybrid five-switch and five-level inverter for grid-connected PV system was introduced.The inverter consists of a full-bridge inverter circuit and an auxiliary circuit comprised of four diodes and a switch.The added auxiliary circuit made the output of the conventional three-level full-bridge inverter circuit into five levels.The working process of the five-switch and five-level inverter was analyzed,and the SPWM control strategy of a reference signal alternately comparing with two carrier signals was used to obtain the switch signals of five switches.The feasibility of the proposed inverter was verified through simulation.The simulation results showed that the output voltage and current of the inverter had low THD and the grid-connected current was synchronous with the grid voltage and met the grid-connected requirements.