Design and Implementation of a Wide-Input Reconfigurable Three-Level Dual Active Bridge Converter for High-Voltage On-Board Charging Applications

Abstract

The demand for reducing fast charging times and run-time losses in the powertrain of an electric vehicle has created a push for increasing the high voltage (HV) battery pack’s voltage level. 800 V class vehicles in mass 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) planned for the electrification of medium to heavy-duty vehicles have voltage levels defined up to 1.5 kV and 1.25 kV, respectively. The SAE J3068 standard, focused on 3 Φ AC charging recommends compatibility from 208/120Y to 600/347Y V, resulting in a large DC link variation of the power factor correction (PFC) stage’s DC link. To accommodate the voltage swing on the DC link of the PFC stage, this thesis proposes a reconfiguration method of a neutral-point clamped (NPC) converter incorporated in a three- level dual active bridge (DAB) converter. 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 procedure for this converter is established to choose the switching frequency, turns ratio, and leakage inductance. 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.