| Abstract |
This article firstly presents a detailed analysis and improvement for the dual active bridge employingMMC cells (MMC-DAB converter). The presence of MMC cells can effectively address the concernthat medium or high voltage level is beyond voltage rating of semi-conductor devices in conventionalDAB converter. However, the introduction of MMC cells results in significant losses originated fromresonance between line inductor and sub-module capacitor. Besides, the non-negligible switching loss is another factor of efficiency drop. In order to solve the additional losses and improve the overall conversion efficiency, this article proposes three innovative switching algorithms, where manipulating cell states to stop current oscillation and enable zero voltage switching (ZVS). Simulated results for a medium voltage level MMC-DAB converter is provided to verify the efficiency gain under optimal switching algorithms. Moreover, a 2-level MMC-DAB converter is implemented and the experimental result shows the proficiency of the converter. |
