Three-Phase Three-Level Dual Active Bridge for EV Charging: Wide Output Voltage Range with Light-Load Soft-Switching Morphing

This manuscript focuses on effective modulation techniques that enable the extension of soft-switching operations for a three-phase three-level dual active bridge under light-load conditions at both 400 V and 800 V, typical for electric vehicle batteries, without the need for auxiliary switches. The proposed methods take advantage of the high switch count typical of the three-phase three-level structure, allowing it to be reconfigured into a single-phase dual active bridge and a hybrid configuration composed of one half-bridge at the input and one full-bridge at the output with double transfer inductance. These reconfigurations significantly reduce the number of switching events, minimize current-invariant losses, and ensure zero-voltage switching turn-on for both the input and output bridges due to the unity voltage gain ratio at both 400 V and 800 V, resulting in enhanced efficiency during light-load operation.