摘要
Z源逆变器光伏发电系统是一种具有升/降压功能的单级系统。它可以通过调节直通占空比实现前级光伏电池的最大功率跟踪(MPPT)控制,然后由逆变器调制因子M实现并网控制,简称为两级控制。两级控制策略虽然控制器设计简单,但是在逆变器额定电压输出的情况下,调制因子小、有源元件电压应力和输出电流谐波含量高。本文提出了一种基于统一电压空间矢量的单级控制策略,从系统的角度出发,整合直流链升压电路控制量B和逆变器并网电路控制量U为一个变量——统一电压空间矢量U′。通过控制统一电压空间矢量的长度,进而达到同时控制直通占空比和逆变器调制因子的功能。该策略充分利用了直通零矢量,使逆变器的调整因子M增大,直流电压利用率高,相应地有源器件的电压应力和逆变器输出电流谐波得到很大的改善,并发挥了单级电路整机效率高的优势。实验结果验证了理论分析的正确性与实用性。
Z-source inverter photovoltaic system is a single-stage system, which has buck/boost characteristic. It achieves maximum power point tracking （MPPT） with control shoot-through duty cycle, while fulfills the grid-connection with modulation index control. This paper presents a single-stage control technique for Z-source inverter based PV system. The new unified vector U′ is composed of the traditional vector U and the boost factor , which allows the desired vector to be located anywhere without limitation of the dc input voltage. The output voltage of Z-source inverter can faithfully follow the reference voltage regardless of the variable dc-link input voltage. It increases modulation index M, full utilizes the dc-link input voltage, decreases voltage stress of the active devices and improves the harmonics in output current of the inverter. The theoretical analysis is verified by simulation and experimental results.
出处
《电工技术学报》
EI
CSCD
北大核心
2010年第4期122-128,141,共8页
Transactions of China Electrotechnical Society
基金
辽宁省教育厅基金资助项目(2009A352)
