Bidirectional DC-DC Dual-Active-Bridge Converter with Symmetric Bipolar Outputs Using Triangular Modulation

This article presents a symmetrical bipolar output voltage-based DC-DC dual active bridge converter (DAB) using the triangular modulation (TRM) technique. In the proposed TRM, one arm of the high voltage (HV) side bridge is controlled using time-varying pulse width modulation (PWM), while the remaining arms of both the low voltage (LV) side bridge and the HV side bridge are controlled using time-invariant PWM. As a result of this switching strategy, the DC-DC DAB converter improves its soft switching performance, achieving 1) zero-current turn-on and turn-off for the devices operating on the LV side bridge. 2) zero-voltage turn-on for the devices on the HV side bridge operating with time-invariant PWM. 3) zero-voltage turn-on for the devices on the HV side bridge operating with time-variant PWM. The proposed TRM also ensures soft switching under all loading conditions with simple control, utilizing a single control variable that maintains a linear relationship with power. Simulation results, followed by experimental results of a scaled-down prototype of a 500 W system were developed using the TMS320F28335 for bidirectional electric vehicle DC charging system and EV-to-load applications, achieving an experimental efficiency of 94.7%.