A current stress optimization and improved model reference adaptive control combined strategy for dual active bridge converter

To improve the dynamic performance and the efficiency of DAB converter with unified phase-shift (UPS) modulation simultaneously, based on the characteristic analysis of this system, such as power characteristics, soft switching conditions and current stress, an optimal control strategy combining current stress optimization (CSO) and improved model reference adaptive control (IMRAC) is proposed in this paper. To achieve current stress optimization so as to improve the efficiency of DAB converters in the whole operating range, the optimal phase-shift ratio combination is selected by the Lagrange multiplier method (LMM) with Karush–Kuhn–Tucker (KKT) condition while realizing soft switching under the UPS modulation scheme. Then, based on the established generalized average reduced order (GARO) model of DAB converters, an additional error tracking term reflecting the difference between the actual output and the expected system output is introduced into the reference model of the model reference adaptive control (MRAC), so the dynamic performance of DAB converters can be improved. In addition, the transmission power estimation of DAB converters is introduced to realize the cooperation of the CSO and IMARC. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control techniques. The experimental results show that the strategy proposed in this paper can achieve an efficiency of 94.08% for the DAB converter when the voltage transformation ratio is 1, reduce the current stress to 2.9A, and decrease the recovery time to 140ms.