Research On Three-phase Interleaved LLC Resonant Converter

Single-phase LLC resonant converter can achieve zero-voltage-switching(ZVS)of primary MOSFETs and zero-current-switching(ZCS)of secondary rectifiers.These merits can benefit the power supplies(SMPS)with higher efficency,less EMI noise,lower switching stress and better utilization of parasitic parameters.However,due to its large output current ripples,large volume of electrolytic capacitors are always requied to perform filtering,which takes up much space and also deteriorates in working.These capacitors have impaired further improvements of power supplies in power density and reinforcements in system reliability,and single-phase LLC resonant converter will not qualify heavy load senarios.Two-phase interleaved and three-phase Y-type LLC resonant converters can significantly attenuate the total output current ripples.Therefore,less electrolytic capacitors are requied to be equiped and the total power disspation will also be reduced.Two-phase interleaved LLC resonant converter is investigated first in this work,and according to the analysis,slightly parameter deviation of the resonant tank will generate large power sharing unbalance between the two individual blocks.This sensitivity is difficult to damp in application due to the parameter dispersions of inductors and capacitors.Three-phase Y-type LLC resonant converter is further investigated in detail,which inherits current sharing capability naturally.In this work,the working principle of a three-phase Y-type LLC resonant converter is analyzed first,and then the total output current ripples are calculated and evaluated.A FHA based modeling method is proposed in three-phase Y-type LLC resonant converters,which transforms the three-phase model to a single-phase form,simplifying the modeling calculations.Meanwhile,parameter design method of three-phase Y-type LLC resonant converters are provided,based on which,magnetic integration scheme of transformer and resonant inductor is proposed.Finally,experiments are carried out to verify the proposed modeling and design methods.