基于变步长极值搜索法的三电平光伏MPPT控制

Study of MPPT for Three-level PV Generation Based on Variable Step-size Extreme Seeking Control

为提高光电转换效率,最大功率点跟踪(MPPT)被广泛应用于光伏系统。在常用的MPPT控制算法中,极值搜索(ESC)法因其不依赖对象的数学模型而受到关注。研究了一种以Boost三电平变换器为核心,基于变步长ESC法的光伏MPPT控制算法。该算法不但具有传统ESC的优点,还能自动调节步长,快速跟踪最大功率点(MPP),降低开关频率和功耗。通过仿真与样机实验结果证明新算法在外部环境突变的情况下,能快速准确地跟踪光伏阵列的MPP,具有良好的动态和稳态性能。

In order to improve the photovohaic （PV） conversion efficiency, maximum power point tracking （MPPT） is widely used in PV systems.Among all MPPT schemes, extremum seeking control（ESC） is attractive because it does not rely on the mathematical model.This paper analyzes the principle of Boost three-level inverter and then a MPPT based on variable step-size ESC algorithm is researched.The proposed method has the merits of conventional ESC meanwhile automatically adjusts step-size and quickly to track PV module maximum power point（MPP）.Finally the sim- ulation and prototype experiment with the traditional MPPT algorithms are analyzed.The simulation and experimental result show that the proposed new method can track the MPP of PV array quickly and precisely under sunlight tran- sient large changed, and has a good performance.