An Efficiency Improving Method for LLC Based on Variable Proportion Transformer

In server applications, the use of the two-part voltage regulator module (VRM) structure is becoming more well-known. Because of its efficient output, the LLC converter is the most widely used option for the first stage in order to guarantee great efficiency in the sleep mode for the CPU. A transformer structure presented in this study has a changeable primary copper winding, which allows it to change the total ratio in response to changes in the load. The big ratio mode is used to lower the maximum magnetic flux under light load circumstances, which lowers core losses and boosts efficiency. The results of calculations indicate that under minimal load situations, the magnetic core loss often surpasses the copper loss by a significant amount, even if the scheme may marginally increase the winding loss. An effective 48-12/9.5/5.4 V LLC with a maximum efficiency of 93.5% has been constructed. Tests carried out on VRMs show significant improvements in light-load efficiency as a result of these adjustments.