Research Of Two-inductor Current-fed Bi-directional Converter

With the development of new energy and renewable energy,energy storage system also gets rapid progress.Two-inductor current-fed bi-directional converter receives more attentions with its improvement on the service life of the energy storage unit,and the characteristics of the high voltage gain.However the turn-off voltage spike of the traditional current-fed converter affects the reliability of the circuit and applications seriously.This paper proposes a modified high-voltage-side(HVS)phase shift control scheme.Based on the high-voltage-side modulation scheme,the modified scheme introduces phase shift between the HVS.By adjusting the phase shift angle,the rms of current can be decreased with the reduced peak current and efficiency can be improved.At the same time,the modified scheme can realize natural commutation and ZCS turn-off on the low-voltage-side(LVS)switches,and then restrain the turn-off voltage spike.Based on the traditional two-inductor current-fed bi-directional converter,the forward and backward operation modes of the HVS phase shift control scheme is analysed firstly.Then the relationship between duty cycle and power is derived by theoretical calculation,so as the relationship between the rms current and phase angle: power range and direction is adjusted by the duty cycle,and adjusting the phase shift angle can reduce the peak current and decrease the rms current.However,due to the parasitic parameters of switches and the reverse recovery problem,both the modified scheme and the original scheme can not actually eliminate the turn-off voltage spike.For the purpose of eliminate the turn-off voltage spike,this paper proposes a two-inductor current-fed bi-directional resonant converter.The proposed topology introduces a resonant capacitance compared with traditional two-inductor current-fed bi-directional converter and adopts HVS phase shift control scheme.The proposed topology can implement ZCS turn-off on LVS switches and ZVS turn-on for HVS switches.With the resonant between inductor and capacitance,the turn-off voltage spike is eliminated and ZVS turn-on for LVS switches is realized.For the proposed two-inductor current-fed bi-directional resonant converter,the forward and backward operations are first analysed.Then,aim to the proposed topology,the operation characteristic analysis is done,from four aspects: gain characteristics,power characteristics,ZVS characteristics of HVS and current characteristics.Finally,the simulation and experiment results verify the validity and advantage of the modified scheme.According to the characteristic analysis,a parameter design procedure for the proposed two-inductor current-fed bi-directional resonant converter emerges.A prototype is built with parameters obtained from the procedure.The simulation and experiment results verify the correctness of theoretical analysis from both the modes and operation characteristics.