Full-Bridge vs. T-Type: A Comprehensive Comparison of Three-Phase Power Converters with Variable DC-Link Voltage for EV Fast Chargers

Electric mobility has gained more attention within the transportation sector, where the development of innovative EV chargers must accomplish with the requirement of reduced charging times. Therefore, the implementation of more efficient and faster EV chargers is of utmost importance. This paper presents a comprehensive comparison between two topologies of three-phase AC-DC power converters: a full-bridge and a T-type. The AC-DC power converter must operate with sinusoidal AC current, and since it is linked to a back-end DC-DC isolated power stage, it is convenient the operation with variable DC-link voltage for enhancing the efficiency of the DC-DC stage. Along with the paper, it is presented a comparison regarding the switching power devices, sensors, gate-drivers, control complexity, as well as voltage and current stress in the switching power devices. It also presents an analysis in terms of efficiency and estimated loss distribution for different operating power levels and switching frequencies. In addition, it analyzes the influence of varying power levels and DC-link voltages on the total harmonic distortion of the AC currents. The results were obtained for different conditions of operation and considering balanced power and balanced current from the power grid point of view.