An optimized soft‐start procedure of dual active bridge converter for charging current suppression

Abstract

Abstract As a typical topology of solid‐state transformer, dual active bridge converter (DABC) is widely used for voltage levels conversion due to its advantage in bidirectional power transfer and galvanic isolation. In the start‐up process, an overcurrent will occur when the converter charges the output capacitor. To address this problem, special soft‐start procedures are used to protect switches from the inrush current. The soft‐start framework used in this paper adds an inner‐phase‐shift in the closed loop control. Compared to the conventional step‐to‐step soft‐start methods, it simplifies the transition process from the open loop to the closed loop control. However, higher current stress appears in the soft‐start process. So, based on the framework, an optimized soft‐start procedure with simple implementation, including the phase transformation and the inverse‐trigonometric inner‐phase‐shift, is proposed to improve the voltage tracking performance and reduce the charging current further. The simulation and experimental results confirm the effectiveness of the proposed soft‐start procedure on the output voltage control and charging current suppression.