An Optimal Control Strategy for the DAB-Based Partial Power Converter Based on Extended-Phase-Shift Control

Abstract

Dual active bridge (DAB) converters are extensively used due to the advantages of wide voltage regulation range and easy realization of soft switching. Besides, the concept of partial power converters (PPCs) has been widely applied to increase the converter efficiency by reducing the power actually processed by the converter. Therefore, in this article, the DAB converter and PPC are combined. And a high frequency DAB-based PPC aiming at efficiency optimization is selected out by analyzing and comparing the characteristics of several connections. Considering the wide voltage regulation range of DAB-based PPC, the extended-phase-shift-based control strategy aiming at zero-voltage switching (ZVS) range and current stress optimization is analyzed and adopted in this article. With the trend of high frequency for power converters, the non-ideal factors like output capacitors of switches need to be considered to improve the performance. The output capacitors are taken into consideration when analyzing the ZVS performance and the magnetizing inductor is utilized to expand ZVS range. To verify correctness of theoretical analysis, a prototype using GaN devices with 1 kW rated output power and 500 kHz switching frequency is built. The experimental results are consistent with the analysis.