一种新型共地拓扑的单相非隔离型准Z源光伏并网逆变器研究

Research on a Novel Single⁃phase Non⁃isolated Quasi⁃Z⁃source Photovoltaic Grid⁃connected Inverter Based on Common Ground Topology

准Z源逆变器可以实现升压功能,允许同桥臂上下开关管直通,提高了逆变器的可靠性,但准Z源逆变器存在共模电流,为解决准Z源逆变器的共模电流问题,提出了一种新型共地拓扑的单相非隔离型准Z源光伏并网逆变器。分析了传统准Z源逆变器产生共模电流的原因,改进了准Z源逆变器的逆变拓扑结构,引入虚拟直流母线,通过将光伏阵列和电网的负端共地,旁路由光伏杂散电容构成的共模电流回路,有效解决了单相非隔离型准Z源逆变器的共模电流问题,并介绍了单相非隔离型准Z源逆变器的工作模式,改进了新拓扑的PWM控制策略,最后通过仿真验证了该逆变器的可行性。

The quasi⁃Z⁃source inverter can realize the boost function,allow the upper and lower switches of the same bridge arm to pass through,which improves the reliability of the inverter.It,however,has common mode current.In order to solve the common mode current problem of the quasi⁃Z⁃source inverter,a kind of novel single⁃phase non⁃isolated quasi⁃Z⁃source photovoltaic grid⁃connected inverter based on common ground topology is proposed.The reason for the common mode current generated by the traditional quasi⁃Z⁃source inverter is analyzed.The inverse topology of the quasi⁃Z⁃source inverter is improved,the virtual DC bus is introduced,the photovoltaic array and the negative terminal of the power grid are grounded together,the common mode current loop composed of photovoltaic stray capacitors can be bypassed and the common mode current problem of single⁃phase non isolated quasi⁃Z⁃source inverter is effectively solved.The work mode of the single⁃phase non⁃isolated quasi⁃Z⁃source inverter is introduced and the PWM control strategy of the new topology is improved.Finally,the feasibility of the inverter is verified by simulation.