An Optimized DPS Control for Dual Active Bridge Converters to Secure Full Load Range ZVS with Low Current Stress

Abstract

It is a challenge for dual active bridge (DAB) converters to take good balance between full load range zero-voltage-switching (ZVS) and control complexity with wide voltage range. Dual phase shift (DPS) control can extend ZVS range greatly compared with single phase shift (SPS) control, and it has less control variables with reduced operation modes compared with triple phase shift (TPS) control. However, with conventional DPS control, at least a pair of switches will be operated under hard switching within a large power range, which severely reduces the efficiency especially at high switching frequency. To solve this problem, based on Lagrange multiplier method (LMM), an optimized DPS control utilizing magnetizing current is proposed. In this paper, the magnetizing inductance is designed to create possibility of full load range ZVS achievement for all power switches. Based on ZVS analysis considering switch junction capacitors and power characteristics analysis, a power control law premised on full load range ZVS achievement is proposed to achieve low current stress. Finally, the effectiveness of the proposed solution is verified by experimental results obtained with a 500W, 250kHz GaN-Based prototype.