Performance Characterization of T-Type Multilevel Dual Active Bridge DC-DC Converter

Conventionally, single phase shift control technique is used for controlling dual active bridge (DAB) performance, which works efficiently at unity voltage conversion ratio and full load. However, when there is mismatch between primary voltage and reflected secondary voltage on primary side at light load, its efficiency reduces because of increased current stress and reactive power. Moreover, due to single control variable, its power flow controllability is confined. In this paper, analysis, implementation and performance characterization of isolated bi-directional T-type multilevel dual active bridge DC-DC converter topology is presented. It has five level voltages on both the primary and secondary side of high frequency transformer, which reduces the current stress and reactive power over wide operating range. It also has five control variables which gives extra edge for enhancing power flow controllability. Comparative analysis reveals that the proposed converter has high efficiency over wide operating range, due to reduced reactive power and current stress. Performance of the proposed T- type multilevel dual active bridge DC-DC converter topology has been verified via simulation and experimental prototype developed in the laboratory.