Design of a soft-switched three-port converter with DSP control for power flow management in hybrid fuel cell systems

A zero-voltage-switched three-port bidirectional converter which is able to handle wide input voltage ranges such as fuel cells and supercapacitors is presented in this paper. The converter consists of three active bridges coupled by a three-winding transformer. A simplified duty cycle control method is introduced to extend the soft-switching range. The system is modeled and a dual-PI-loop control strategy is proposed to achieve regulated output voltage and power flow management. In addition, the soft start-up procedure for the converter is discussed. Simulation and experimental results on a 1 kW prototype verify the effectiveness of the proposed converter and its control strategy