【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。更多还原

【Abstract】 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.更多还原