分布式发电应用下宽输入LLC谐振变换器的研究

Research on Wide Input LLC Resonant Converter for Distributed Generation Applications

为解决新能源分布式发电系统中发电单元输出电压范围较宽,后级变换器输入电压不稳定的问题,研究设计了一种高功率密度、高效、宽输入范围的全桥LLC谐振变换器。为适应宽输入电压的条件,采用对比分析的方法总结出变频和移相混合控制下的增益曲线,结合最佳的模式切换点,实现了宽输入条件下工作的高效率;主控芯片选用UCC3895使电路的控制更加简便,并且保证了输出电压的稳定性。最后制作了一台额定功率为2 kW,输入电压为250~500 V的实验样机,通过实验数据的测试分析验证了理论分析的正确性。

A full-bridge LLC resonant converter with high power density,high efficiency and wide input range is designed to solve the problems that the output voltage range of the power generation unit is wide and unstable input voltage of the post-converters in the new energy distributed generation system.In order to adapt to the condition of wide input voltage,the gain curve under the mixed control of frequency conversion and phase shifted is summarized by the method of comparative analysis.Combined with the best mode switching point,the high efficiency under the condition of wide input is realized.UCC3895 is selected to make the control of the circuit easier and ensure the stability of the converter output.Finally,an experimental prototype with 2 kW and input voltage of 250~500 V is made.The correctness of the theoretical analysis is verified by testing and analyzing the experimental data.