Novel Modulation Technique Based Bidirectional DC to AC Dual Active Bridge for G2V and V2H

In this article, a triangular modulation based variable frequency modulation technique for a single-phase single-stage isolated bidirectional DC to AC dual active bridge has been proposed. The proposed modulation technique requires a single carrier and can be realized using two different methods. Distinctively in method 1, 50% gating signal is provided to the AC side bridge and one leg of the DC side bridge without any phase shift. However, there exists a center-to-center (C2C) phase shift between the gating signal of two legs of DC side bridge where one leg of DC side bridge is operating at 50% duty cycle and another operating at sinusoidally modified variable frequency pulse width modulation (PWM). In method 2, no C2C phase shift exists between the gating signal of the two legs of the DC side bridge. In this case phase shift exists between bridges operating at 50% duty cycle. Presented techniques offer true zero current switching (ZCS) for the AC side bridges over the wide envelope of the line frequency, zero voltage switching (ZVS) turn ON and ZCS turn OFF for the DC side switches, near unity power factor, bidirectional power flow with improved efficiency of 96.19%. DSP based digital realization of both methods is elaborated in detail and out of the two methods, the implementation of method 1 is presented in this article. The concept is validated through simulation results and experimentation on a 500 W prototype using TMS320F28335 for vehicle-to-home (V2H) and grid-to-vehicle (G2V) applications.