基于滞环控制的Z源三相全桥光伏并网系统的研究

RESEARCH ON Z SOURCE BASED THREE-PHASE FULL-BRIDGE PHOTOVOLTAIC GRID-CONNECTED SYSTEM USING CURRENT HYSTERESIS CONTROL

综合滞环和Z拓扑的控制特点,提出了一种适用于Z源三相全桥并网系统的电流滞环控制策略,根据全桥的特点,解决了直通时间的插入与各相同步的问题。由于定频控制,降低了开关损耗,易于滤波环节的设计。保留了滞环控制下动态响应快、精度高、稳定性好等特点,有效跟踪电网电压。各相独立控制,参考电流可独立设置。Z源的升压,增大系统并网电流,提高光伏系统并网功率。通过仿真与实验分析,证明该策略的可行性。

Z-source based PV grid-connected systems, using hysteresis control in three-phase full-bridge circuit, inserting straight through time synchronously, was studied. By summarizing control features of both hysteresis and Z topology control, a fixed-frequency grid connected control strategy used in three-phase Z-source based PV systems was proposed. This control strategy was good at fast response,high accuracy ,high stability, etc. Grid voltage was tracked effectively. Using fixed-frequency control, filter circuits was easy to be designed. According to the characteristics of full-bridge, straight through time was successfully inserted, it was easy to be controlled by DSP. Because of the independent control of each phase, the reference current can be set independently. For PV systems, fluctuation of DC side voltage within a certain range was allowed. With the control of the algorithm, through the effect of Z Source Boost, Grid current was increased significantly. Both comparison with the traditional hysteresis control by simulation and grid connected experiment proved the feasibility of the algorithm.