Abstract: The LLC resonant converter has the advantages of soft switch,low EMI,high power density,etc.It is widely used in communication power supply,LED,vehicle power supply and other fields.Under the condition of wide output range,for the calculation process of resonator,a waveform template calculation method is provided at the low resonant frequency,so as to obtain the accurate parameters of resonator.The parameters of LLC during resonance are simulated on the platform of Simplis.The simulation results verify the rationality of the parameter design.

Key words: resonant converter, soft switch, parameter design, high efficiency