A Simplified-ISOP-CLLLC Converter with Wide Voltage Gain for Auxiliary Power Supply Systems of Urban Rail Vehicles

Inhalt:
An input-series-output-parallel (ISOP) CLLLC bi-directional converter with a reduced number of switches is proposed for the auxiliary power supply system of urban rail transit vehicles. Unlike the conventional ISOP structure, the two transformer outputs on the secondary side is in parallel, connected to one resonant tank and one synchronous rectifier circuit. A novel control strategy is proposed to realize zero voltage switching (ZVS) for all switches. A novel control strategy is proposed to realize wide voltage gain, adapted to the fluctuation of DC bus. The principle of operation during forward power operation is analyzed and soft switching is analyzed taking into account the junction capacitance of all switches. A 40kW simulation prototype is built to verify the effectiveness of the proposed solution. The simulation results prove the correctness of the converter with the proposed control strategy and show that it is capable of achieving ZVS turn-on at full load and light load.