Flux control modulation for the dual active bridge DC/DC converter

Abstract

This paper introduces a modulation technique for the single-phase dual active bridge (DAB) in which the switching frequency and transformer flux linkage are modulated to achieve improved power transfer characteristics and reduced converter losses. By analysing the DAB, it is noticed that in the traditional single phase shift (SPS) modulation, the transformer flux linkage decreases with increasing power. The proposed flux control modulation (FCM) counteracts this decrease and aims to keep the transformer utilisation constant on the whole load range by a reduction in switching frequency. This has two effects: first, the reduced frequency substantially lowers switching losses and second, the power transfer characteristic of the DAB is linearised, facilitating the control of this converter. The new modulation technique is validated by simulation.

Keywords

• bridge circuits
• DC-DC power convertors
• switching convertors
• flux control modulation
• dual active bridge DC/DC converter
• novel modulation technique
• single-phase dual active bridge
• DAB
• switching frequency
• improved power transfer characteristics
• converter losses
• traditional single-phase shift modulation
• transformer flux linkage
• increasing power
• transformer utilisation
• reduced frequency
• power transfer characteristic