基于LLC变换器的变权重DFC光伏MPPT算法

Variable Weight DFC Photovoltaic MPPT Algorithm Based on LLC Converter

太阳能具有清洁、可持续等优势,被广泛应用于光伏发电,而最大功率点追踪(MPPT)是光伏发电的关键技术。针对基于LLC变换器脉冲频率调制(PFM)控制的中心点迭代MPPT法迭代次数过多,导致追踪速度较慢的问题,此处提出一种变权重直接频率控制(DFC)光伏MPPT算法,通过对比中心点迭代法和不同权值迭代法的光伏功率和开关频率曲线,在中心点迭代法的基础上增加了每次迭代的权重因子,根据划分的区域及对应点的dP/df,确定每次迭代的权重因子的值,实现快速MPPT控制。试验结果表明,所提变权重DFC法较传统中心点迭代法在进入最大功率点范围过程中迭代次数少,提高了追踪速度和稳态精度。

Solar energy is widely used in photovoltaic power generation due to its advantages of cleanness and sustainability,while maximum power point tracking(MPPT)is the key technology of photovoltaic power generation.The center point iteration MPPT method based on LLC converter pulse frequency modulation(PFM)control has too many iterations,which leads to the problem of slow tracking speed.A variable weight direct frequency control(DFC)photovoltaic MPPT algorithm is proposed,by comparing the photovoltaic power and switching frequency curves of the center point iteration method and different weight iteration methods,the weight factors for each iteration are added on the basis of the center point iteration method,according to the divided area and the dP/df of the corresponding points,the values of weight factors for each iteration are determined to achieve fast MPPT control.The test results show that the proposed variable weight DFC method has fewer iterations than the traditional center point iteration method in the process of entering the maximum power point range,and improves the tracking speed and steady-state accuracy.