Abstract

Multilevel dual-active-bridge (ML-DAB) is a cutting-edge converter configuration designed to enhance the performance of DC-DC conversion, particularly in medium-voltage electric vehicle charging applications. ML-DAB offers improved voltage-blocking and power range capability compared to traditional DAB converters. In this paper, a switch-control scheme for a T-type neutral-point-clamped (TNPC) DAB DC-DC converter is presented. The key novelty of the proposed modulation scheme is the reconfigurable operation of the TNPC-based DAB converter among six different power configurations without the need to modify the implementation scheme. In fact, by only changing two modulation angles, two to five levels can be generated. The contribution of the paper is the implementation of a switch control and state machine schemes that allows working on a reconfigurable ML-DAB topology with different improved figure-of-merit (FOM) performances. The evaluation of the maximum combined efficiency curve highlights that the half-bridge, DAB and proposed ML-DAB configurations exhibit better efficiencies at low, medium and high power ranges, respectively. Experimental tests under a scaled-down power prototype to verify the proposed modulation method and control scheme implementation are performed. © 2013 IEEE.