A Combined Control for Efficiency Improvement of Integrated Three-Port Dual Active Bridge Converter

In conventional single phase shift (SPS) control for the dual active bridge (DAB), the efficiency at light load is poor. While operating in dual-phase shift (DPS) control, the light load efficiency improves to some extent, however, the current stress at heavy load becomes higher than in SPS control. Importantly, the DPS control suggested in the literature does not converge to SPS control near heavy-load conditions. This paper proposes a novel approach for a three-port DAB converter by synergistically combining the techniques of SPS and DPS. Importantly, it provides a clear demarcation between the SPS and DPS regions of operation to achieve a high-efficiency profile over a wide range of operations. It covers the detailed analysis of different modes of operation based on the zero-crossing instant of leakage inductor current. In addition, an efficiency and current stressed comparison is provided among the SPS, DPS, and combined control approach for various load conditions. The operation of the proposed technique is also validated with a 2.6 kilowatt prototype.