A 15-kW Wide-Input Reconfigurable Three-Level DAB Converter for On-Board Charging of 1.25-kV Electric Vehicle Powertrains

The demand to reduce charging time and run-time losses in electric vehicles has created a push to increase the battery pack’s voltage level. An 800-V class vehicles in production are approaching the 1-kV voltage limit of the combined charging system (CCS) connector. New fast charging standards, such as ChaoJi (CHAdeMO 3.0) and megawatt charging system (MCS), have voltages defined up to 1.5-kV and 1.25-kV, respectively. The SAE J3068 standard, focused on three-phase (3- $\Phi $ ) ac charging, recommends compatibility from 208/120Y to 600/347Y, resulting in a wide voltage variation of the power factor correction (PFC) stage’s dc link. This article proposes a reconfiguration method of a neutral-point clamped (NPC) converter in a three-level dual active bridge (DAB) converter to accommodate the wide voltage swing. The reconfigurable three-level DAB converter (R3L-DAB) topology is introduced, and its modes of operation are presented. The steady-state analysis and its soft-switching criterion are discussed. A power loss model and design methodology are established to choose the switching frequency ( $f_{\textrm {sw}}$ ), turns ratio ( $n$ ), and leakage inductance ( $L_{k}$ ). Finally, the experimental results of a 15-kW R3L-DAB converter, with a power density of 3.25 kW/L and peak efficiency of 97.32% are presented.