A Simple Power Estimation With Triple Phase-Shift Control for the Output Parallel DAB DC–DC Converters in Power Electronic Traction Transformer for Railway Locomotive Application

Abstract

Aimed at the input-independence and output-parallel dual-active-bridge (DAB) dc–dc converters applied to power electronic traction transformer (PETT), this paper proposes a simple power estimation scheme with triple phase-shift control (PES-TPS) to achieve the transmission power balance, dynamic performance improvement, and efficiency optimization, simultaneously. Through executing the current stress optimization (CSO) and introducing the power estimation based on operational parameters, the efficiency of converters can be further improved and the power balance among DAB cells can be achieved over the whole power range without adding extra sensors to sample the output/inductor current of each cell. In addition, the dynamic performance of the adopted converters can be improved by compensating power loss online. Especially, dynamic response of the output voltage can be enhanced under input voltage and load fluctuation conditions. Finally, a comprehensive experimental comparison of CSO with dual phase shift (CSO-DPS), CSO with TPS (CSO-TPS), and the proposed PES-TPS control is conducted in the DAB converters experimental prototype with three cells. The experimental results have confirmed the excellent performance of the proposed PES-TPS control and the correctness of the theoretical analysis.