Small Signal Analysis and Control Design of Snubberless Naturally Clamped ZCS/ZVS Current-Fed Half-Bridge DC/DC Converter for EV

This paper presents a systematic derivation of a small signal model of current-fed half bridge isolated dc/dc converter for the hybrid electric vehicle based on the lithium battery and fuel cell. The reflected output voltage across the power semiconductor devices can naturally be clamped at V°/n by a secondary-modulation strategy without any additional circuit, which can reduce footprints and cost. Moreover, the soft switch of all can be achieved resulting in low switching losses and higher efficiency due to ZCS/ZVS. In order to maintain the constant bus voltage and the balanced two-way inductor current, a small signal model using state-space averaging technique is deduced and the dual closed loop controller is designed in detail. The co-simulation of PSIM and MATLAB/SIMULINK is used to verify the effectiveness of the controller when the load step-changes in case of the different input voltage.