新颖的三相Boost型光伏并网逆变器

Novel Three-phase Boost Mode Photovoltaic Grid-connected Inverter

提出一种新颖的三相Boost型光伏并网逆变器,并对其拓扑、双环改进型分区SPWM控制策略、低频模态、储能开关关断电压尖峰抑制、高频开关过程、光伏电池最大功率点跟踪(maximum power point tracking,MPPT)、关键电路参数设计准则等进行了深入的分析研究,获得了重要结论。其拓扑是由输入滤波电容、中心抽头储能电感、三相逆变桥、三相输出滤波器级联构成,且在储能电感中心抽头与输入源负端间接有储能开关;其控制策略是对三相电网电压进行60°分区,以确保每个开关周期均满足Boost型变换器的工作机理。设计并研制了3kW 96VDC/380V 50Hz 3φAC逆变器,实验结果表明,这类逆变器具有升压比大、功率密度高、变换效率高、储能电感和输出滤波器小、并网电流质量高等优良性能,在单级三相低压并网逆变场合具有重要应用前景。

A novel three-phase Boost mode photovoltaic （PV） grid-connected inverter was proposed. The topology, two-loop modified zone SPWM control strategy, low frequency mode, suppression of the energy storage switch turn-off voltage spike, high frequency switching process, maximum power point tracking （MPPT） of PV cells and design criteria of key circuit parameters were deeply investigated, and important conclusions were obtained. The circuit topology is a cascade of the input filter capacitance, the center-tapped energy storage inductance, three-phase inverting bridge and three-phase output filter, and there is an energy storage switch connected between the center tap of the energy storage inductance and the negative end of the input source; the control strategy is that three-phase grid voltage is divided by 60° to guarantee the operating mechanism of the current converter is satisfied in every switching period. The experimental results of the designed and developed 3kW 96VDC/380V 50Hz 3φAC inverter have shown that this kind of inverter has the excellent performances such as high voltage transmission ratio, high power density, high conversion efficiency, small the storage inductance and output filter, and high quality grid-connected current, which has important application prospect in single-stage three-phase low-voltage grid-connected inverting fields.