Instantaneous Current Balance Modulation for Fast Transient Response in a Dual-Active-Bridge Converter

In the dual-active-bridge (DAB) dc-dc converter, the possible existence of dc bias current in high-frequency (HF) transformer and series inductor can lead to transient magnetic saturation and a series of complex electromagnetic problems. One possible reason for the transient dc bias is due to the sudden changes of phase-shift ratios. This paper presents an instantaneous current balance modulation (ICBM) to eliminate the dc bias and overcurrent in transient states. Through theoretical analyses, mathematical derivations and experimental tests, it was proved that the ICBM can result in a shorter transient response time and better transient performance for DAB converters in active power adjustments.