基于电流源半桥变换器的光伏直流模块研究

Study on DC Photovoltaic Module Based on Current-Fed Half Bridge Converters

研究了一种应用于光伏直流模块的电流型半桥变换器,通过对该变换器工作原理的分析,指出了该变换器在控制时存在控制信号重叠而导致其起动较为困难及轻载不易控制输出电压的问题。针对上述问题,提出了一套基于数字控制和模拟控制相结合的优化控制方案,并对变换器进行了综合的设计。在250W的光伏直流模块样机上进行了实验研究,实验结果表明:所提出的一套控制方案能够使电流型半桥变换器在高频工作情况下,完成基本的MPPT控制或输出电压控制(由变换器功率状态决定),同时实现对变换器起动和轻载工作问题的优化。

A DC- module for photovoltaic applications based on current-fed half bridge converter is discussed. By analyzing the working principle, two problems which are mainly caused by the overlaps of the drive signals are revealed: the converter is hard to start and is suffered from the output control on the light load conditions. Then, an optimized control strategy which combines is proposed to overcome the digital and analog control the above problems, and combine the digital and analog control, to set up the control circuit. The experiments are implemented on a prototype of 250 W rated power. The results show that the proposed control strategy can assure the basic MPPT control or output control(Decided by the power condition of the converter), and meanwhile optimize the start and the light load control issues.