摘要
Z源逆变器(ZSI)/准Z源逆变器(qZSI)利用独特的阻抗源网络和直通调制手段,可在单级系统中同时实现升/降压和直流-交流逆变的功能,适用于具有较大输入电压变化的光伏并网发电系统。本文以具有连续电流输入的电压源型准Z源逆变器为例,分析了基于ZSI/qZSI的光伏并网系统工作原理;针对ZSI/qZSI特殊的直通占空比与逆变调制系数制约关系,推导出ZSI/qZSI正常工作条件下的电容电压范围,提出ZSI/qZSI光伏并网系统的电容电压恒压控制策略。该控制策略将最大功率点跟踪(功率控制)和光伏系统入网电流控制(电能质量控制)解耦,简化了控制器设计,实现了ZSI/qZSI光伏并网系统的闭环控制和最大功率点跟踪,同时可确保在同等输出输入电压比的情况下开关器件电压应力最小。
With unique impedance network and shoot-through,Z-source inverter（ZSI）/ quasi-Z-source inverter（qZSI） can realize buck/boost and DC-AC conversion in a single stage system.It is suitable for grid-connected photovoltaic（PV） power generation systems,where the input voltage varies in a wide range.By taking voltage-source qZSI with continuous input current as an example,this paper provides voltage boost theory and circuit operation principle of the ZSI/qZSI.Based on the demanded mutual limitation of the shoot-through duty ratio and modulation index for ZSI/qZSI,the capacitor voltage range of ZSI/qZSI is investigated and a constant capacitor voltage control strategy is presented for ZSI/qZSI based grid-connected PV systems.The proposed control strategy decouples maximum power point tracking（MPPT）（for power flow control） and grid current control（for power quality）;simplifies the controller design;realizes closed-loop control for the ZSI/qZSI grid-connected PV system as well as MPPT.Moreover,the proposed control strategy ensures minimum voltage stress on switching devices when with the same input and output voltage level.
出处
《电工技术学报》
EI
CSCD
北大核心
2011年第5期62-69,共8页
Transactions of China Electrotechnical Society
关键词
Z源/准Z源逆变器
光伏
并网
最大功率跟踪
恒压控制
直通
升压
Z-source/quasi-Z-source inverter
photovoltaic
grid-connected
maximum power point tracking
constant voltage control
shoot-through
voltage boost
