Deriving the Operating Region for Intermittent Control of Triple Active Bridge to Suppress Cross-currents between Power Supplies

Abstract

Triple active bridge (TAB) DC/DC converters have attracted attention in power distribution systems because of their ability to connect multiple DC power sources organically. In previous research, it is reported that the reactive power increase owing to cross-currents between the power sources in operating areas with imbalanced power loads. This paper proposes a control method to suppress such cross-currents by intermittently turning off all the gates of a specific active bridge connected to the power source. Moreover, a power transmission model is derived, and the control parameters are calculated by formulating the power factor optimization problem based on the model. Experiments were conducted to verify the advantages of the proposed control method. The results showed that the proposed control method was useful in about 10% of the total operating area. In addition, it was confirmed that the power conversion efficiency was improved by about 3 percentage points at the operating point where the cross-currents were maximally reduced.