Research On A Novel Phase-shifting Four-phase Full Bridge DC/DC Converter

Solar energy is inexhaustible,clean and pollution-free,so it is widely studied.When photovoltaic cells are incorporated into DC micro-grid,the photovoltaic cells' voltage is very low,so a step-up converter is needed.In order to ensure the security of electric,photovoltaic cells need an isolated DC/DC converter to connect to DC bus.The power of DC micro-grid is above 10 kW,below 30 MW,so the power of the DC/DC converter in DC micro-grid is becoming larger and larger.Consequently,in order to incorporate photovoltaic cells into micro-grid,studies on high efficient,high-power,isolated,step-up DC/DC converter are needed.Based on the two-phase interleaved phase-shifting full bridge DC/DC converter,a novel four-phase phase-shifting full bridge DC/DC converter is proposed.By phase-shifting control,all the primary switches can realize zero voltage switch(ZVS),so the proposed converter is high efficient.The proposed converter has four transformers and eight switches each side,so the proposed converter is high-power.The topology of the proposed converter can realize isolation booster.Consequently,the proposed converter is a high efficient,high-power,isolated,step-up DC/DC converter,very suitable for connecting photovoltaic cells to DC bus.This paper firstly introduces the topology derivation and operating principle of the proposed converter.Then operating characteristic of the proposed converter is analyzed.Compared with the two-phase interleaved phase-shifting full bridge converter,the proposed converter shows advantages in decreasing the turns ratio of the transformer by half and decreasing current stress of the primary switches and volume of inductance and each transformer.Then according to the design index,the parameters of the proposed converter are designed,the losses are analyzed.Lastly,a 48 VDC input 380VDC/3kW output prototype was established.The experimental results are consistent with the theoretical analysis.The experimental results verify that the proposed converter is a high efficient,high-power,isolated,step-up DC/DC converter.