Stable Operation Limits in Dual Active Bridge for SuperCapacitor Applications

This paper presents an idea for limiting the phase-shift angle in Dual Active Bridge (DAB) which ensures the converter’s stability. The stability is the main criterion in a converter’s operation without which the converter will stop working. In an ideal DAB which comprises of ideal components, the phase-shift angle limit is 90o. We developed a detailed model in Matlab/Simulink for DAB based on which the limits for the stable operation of converter are derived. In the developed model, attempts are made to employ as accurate as possible models for the components. In this way, the limits are expected to be very close to the practice. The DAB is a bi-directional converter; meaning that the power flow occurs in both forward and reverse directions. We derived the limits separately for forward and reverse modes. It is shown that the limits are the same for both directions confirming the fact that the DAB is symmetrical. We employed the DAB as the SuperCapacitor (SC) energy storage’s interface in this paper.