Loss Analysis of Duty Controlled SiC 3 Level LLC Converter for Wide Input Voltage Range

In this paper, power losses in a duty-controlled single-stage 3-level LLC converter used for the auxiliary power supply of railway vehicles are analyzed and verified. By this converter, the pre-regulated boost converter is eliminated by controlling the below resonance frequency of the LLC converter and using duty control. Experiments are conducted to compare the power losses of a 3 kW-class LLC resonant converter using duty control and frequency control methods