Abstract: Based on the application background of actual solar unmanned aerial vehicle, this paper conducts indepth research on its core power conversion part. By adding a small number of passive components on the basis of the traditional synchronous rectification Boost converter, using the continuity of the inductor current to construct the output capacitor discharge link of the power switch, the zero voltage switching of the power switch can be achieved while ensuring that the main power inductor current ripple is small. It overcomes the problem of large inductor current ripple when the traditional synchronous rectification Boost converter works in quasi-square-wave mode for soft switching. This helps to extend the service life of the UAV battery pack. Starting from the modal analysis of the topology, this article analyzes the realization process of the zero voltage switching of the power switch in detail. In addition, the parameter design of the converter is carried out, and the main loss calculation method of the whole converter is summarized. Finally, using GaN power switching devices, an experimental prototype with a rated power of 500 W was built and compared with the synchronous rectification Boost converter under the same working conditions. The experimental results are basically consistent with the theoretical analysis, and the peak efficiency reaches 96%. Verifying the accuracy of theoretical analysis and the practical feasibility of the topology.

Key words: solar energy, PV power, UAV, soft switching, conversion efficiency, quasi-square-wave converter

摘要： 基于实际太阳能无人机的应用背景,对其核心功率变换部分展开深入研究。通过在传统同步整流型Boost变换器基础上增加少量无源元件,利用电感电流的连续性,构造功率开关输出电容放电环节,在保证主功率电感电流纹波较小的情况下实现功率开关的零电压开通,克服传统同步整流型Boost变换器为实现软开关而工作于准方波模式下,电感电流纹波较大的问题,从而有助于延长无人机蓄电池组的使用寿命。从该拓扑的模态分析出发,对功率开关的零电压开通实现过程进行详细分析。此外,对变换器进行参数设计,总结整个变换器的主要损耗计算方法。最后,利用GaN功率开关器件,搭建一台额定功率为500 W的实验样机,并与相同工况下的同步整流型Boost变换器进行对比。实验结果与理论分析基本一致,峰值效率达到96%。验证了理论分析的准确性以及该拓扑的实际可行性。

关键词: 太阳能, 光伏发电, 无人机, 软开关, 转换效率, 准方波变换器