Single Stage Isolated Totem Pole Integrated Current Fed Dual Active Bridge Based AC-DC Converter For Electric Vehicle Charging Application

In this paper, a converter solution for single stage AC-DC conversion suitable for electric vehicle (EV) charging application is designed and modeled. On the grid side (primary side), the converter has interleaved totem pole structure while on the DC side (secondary side), it has interleaved boost interface. Both sides are isolated by high frequency transformer(HFT). The interleaved totem pole structure is non regulated and works at a fixed duty of 0.5. Power flow is regulated by controlling the phase difference between the high frequency voltages across transformer. Duty cycle of secondary side bridge is modulated to maintain the THD and unity power factor operation of the converter. Two different approaches, fixed duty modulation and variable duty modulation, are discussed. Simulations are carried out in MATLAB/Simulink platform. Simulation results confirm the inherent capability of the converter to maintain unity power factor with duty cycle modulation with fixed coefficient but for a narrow power range. On the other hand, variable duty modulation with variable coefficient reveals power factor correction capability for wide power range. A simple look up table (LUT) approach is adopted for varying the secondary side duty under variable duty modulation technique.