Start-up Procedure and Soft-starting Strategy for Dual Active Bridge Converter

Dual active bridge converters are widely used in applications with high power density and bidirectional power transmission, such as distributed energy, energy storage systems, and electric vehicles. Aiming at the problems of DC bias and shock of the inductor current during the start-up of the dual active bridge converter, this paper focuses on the analysis of the start-up process of the dual active bridge converter with active load at two start timings and proposes two new soft-start methods. The first method is to achieve fast soft start by changing the start timing. And the second is to gradually increase the duty cycle of the square wave voltage of the AC sides of the H-bridge and adjust the output current reference simultaneously to achieve the soft start of the DAB converter.Finally, the effectiveness of the theoretical analysis of the start-up process of the DAB converter with active load and the proposed method for suppressing start-up inrush current and DC bias are verified by simulation.

I. Introduction

In order to reduce environmental pollution and alleviate the energy crisis, wind power, photovoltaic power generation and other technologies that can generate electricity in bioenergy are gradually gaining attention and development. Therefore, the flexible connection of renewable energy and distributed energy to the power grid has become a research hotspot for scholars. The DC distribution system based on the DC bus has emerged at the historic moment. The isolated bidirectional DC-DC converter is its core link. It has functions such as electrical isolation, bidirectional power transmission, and step-up / step-down voltage conversion.