Current-prediction based transient control of a Dual-Active-Bridge converter with frequency modulation

Step-change of the load in a DAB converter through direct changing of the frequency may cause temporal DC bias current easily, which could induce magnetic saturation, with associated noise, overheating, vibration etc. The proposed transient strategy in this article is to achieve instant switching frequency change by predicting the transformer current in the destined state. The transient overshoot current can be eliminated and total response time is reduced. Two methods with different transient processes are proposed and analyzed. Both simulation and experimental results validate the feasibility of the proposed methods, which may achieve fast transient step-load modulation in a frequency modulated DAB converter without introducing undesired overshoot and dc bias.