新颖的单级三相电压型准Z源光伏并网逆变器

Novel Single-stage Three-phase Voltage-fed Quasi-Z-source Photovoltaic Grid-connected Inverter

提出了一种新颖的强升压能力的单级三相电压型准Z源光伏(photovoltaic,PV)并网逆变器,并对这种逆变器的电路拓扑、改进的空间矢量脉宽调制(space vector pulse width modulation,SVPWM)控制策略和低频工作模式、高频开关过程、外特性等稳态原理特性进行了深入研究,获得了重要结论和电压传输比表达式。该电路拓扑是由大升压比准Z源阻抗网络、三相逆变桥和三相LCL滤波器构成,该改进的SVPWM控制策略为大升压比阻抗网络储能电容电压控制和光伏电池最大功率跟踪(maximum power point tracking,MPPT)外环并网电流内环控制。实验结果验证了采用改进SVPWM控制策略的准Z源逆变器的实际性能。所提出的准Z源逆变器为实现低输入电压或宽变化范围输入电压的新能源并网发电提供了一种有效方法。

The novel single-stage three-phase voltage-fed quasi-Z-source photovoltaic （PV） grid-connected inverter with strong boost ability is proposed in this paper. The circuit topology, the modified space vector pulse width modulation （SVPWM） control strategy and steady principle characteristic were deeply investigated. The steady principle characteristics include the low frequency operation mode, high frequency switching process and external characteristics. And the important conclusions as well as the expression of the voltage transfer ratio were abstained. The circuit topology is composed of a large boost ratio quasi-Z-source impedance network, a three phase inverter bridge and a three phase LCL filter. The modified SVPWM control strategy includes the control for the energy storage capacitor voltage of the large boost ratio impedance network as well as the outer loop control for the maximum power point tracking （MPPT） with the inner loop control for the grid-connected current. The real characteristics of the quasi-Z-source inverter adopting the modified SVPWM control strategy are .verified by the experimental results. So the proposed quasi-Z-source inverter provides an effective method for the new energy grid-connected power generation systems with low input voltages or wide range input voltages.