A Novel Control Method for Eliminating DC Bias in Dual-Active-Bridge DC-DC Converters

This paper proposes a novel transient current control method for dual-active-bridge (DAB) dc-dc converters. When sudden load transients or reference change, the dc bias of inductor current will occur under the traditional control method, which may cause induce magnetic-flux saturation and excessive current spike in the loop. However, a new control method brings the benefit of dynamic performance when disturbance occurs. It can fast achieve new steady state and remove dc offset in dynamic state effectively within half of cycle for inductor current hence preventing magnetic-flux saturation. In this paper, the static and dynamic characteristics of the phase-shift DAB are first analyzed, then the causes of dc bias under the traditional control method are analyzed in detail. On the basis of analysis results, a novel transient control approach is presented to limit the current transient interval in half of switching period. Finally, the experimental model is established and the theoretical analysis is verified by experimental results.