A Reduced Carrier Count Asymmetric Switching Sequence Based Triangular Modulation for Quasi Single Stage AC-DC Dual Active Bridge

Abstract

This article proposes an asymmetrical switching sequence based triangular modulation (TRM) for a quasi single stage (Q1S) bidirectional AC-DC dual active bridge (DAB) converter. In the conventional TRM, both the legs of the DC side full bridge use a symmetrical pulse width modulation (PWM) with the same time period. In the proposed TRM, one leg of the DC-side bridge operates using sinusoidally modified variable time period PWM, while the other leg operates at a fixed time period. In conventional TRM, three carriers with varying phases are used, while the proposed method utilizes only a single carrier. Additionally, conventional TRM demands six enhanced PWM (EPWM) channels, whereas the proposed method requires only four. The advantages of the proposed technique include. 1) Zero voltage switch (ZVS)/zero current switch (ZCS) turns ON for one leg of the DC bridge operating at variable time periods. 2) ZVS turn ON and ZCS turn OFF for another leg operating at a fixed frequency. 3) ZCS turn ON and OFF for the pulsating DC bridge. The proposed TRM also offers open-loop power factor correction (PFC) and unity power factor (UPF) operations. Additionally, the realization complexity was reduced due to the less number of carriers and EPWM modules. The benchmark evaluation was conducted, showing a 14% improvement in real-time code execution time. The proposed technique was implemented using a TMS320F28335 microcontroller and tested on a 500 W lab-scale prototype. © 1972-2012 IEEE.