Regenerative control of bi-directional DC-DC converter controlling variable DC-link for FCEV

FCEV (Fuel cell electric vehicle) is provided with energy for operating the motor from the fuel cell. But fuel cell is impossible to be charged at the regenerative mode and also, it has slow dynamic characteristics. So, additional battery is essential as an auxiliary power source in FCEV system. The output current of the VSI (Voltage Source Inverter) is distorted due to the dead-time and the delay time of switching devices [1]. The ripple of the output current is proportional to the DC-link voltage. So, variable DC-Link control is required to alleviate this problem. In this paper, the bi-directional DC-DC converter controlling variable DC-link is proposed. The proposed converter controls DC-link both motoring and regenerative mode. Also, it chooses the source from among the battery and fuel cell corresponding to the motor speed. The operating modes of converter at motoring and regeneration are presented. Finally, simulation results are presented to verify the reliability of proposed bi-directional converter.