数字控制谐振变换器高轻载效率的研究

Research of resonant converter based on digital control with high light load efficiency

针对传统模拟电源在轻载时损耗较大、效率较低的缺陷，提出了一种基于DSP的PI控制的数字电源设计方法．通过对谐振变换器工作原理、Burst模式工作原理和增益特性曲线等的分析，设置了最佳死区时间，提出了数字控制的Burst模式控制策略，可有效改变轻载模式下的开关频率，从而使得谐振变换器在轻载时也能够实现ZVS ，并减少了变换器关断和传输损耗．实验结果表明：设置合理死区时间的变换器在小于5％额定负载时，其效率能达到87％以上；在5％～20％额定负载时，能够保持93％及以上的效率．Burst控制策略下谐振变换器的有效性和可行性通过仿真和样机实验得到了验证．

To solve the disadvantages of traditional anlog power supply loss and less efficient , the scheme of digital PI control based on the DSP is proposed .A new Burst‐mode control strategy based on digital control is proposed and adjustable dead time is settled by the princi‐ple of LLC resonant converter and Burst‐mode and the analysis of gain curves ,which can im‐prove the switching frequency at light load condition ,ZVS can be achieved ,meanw hile ,the converter switching and transmission loss is reduced ,and the light load efficiency is im‐proved .The resuls show that set the reasonable dead time under 5% load condition ,the effi‐ciency reaches 87 percent ,and in 5% ~20% load condition ,the efficiency is higher than 93 percent .The performance of Burst‐mode control scheme of LLC converter is verified by sim‐ulation and experimental results .