Cooperative Control for Modular DC-DC Converters of Supercapacitor Energy Storage Systems

The supercapacitor tram charges its supercapacitors as passengers enter and exit each station, taking advantage of the short parking time, usually within 30 seconds. However, using a single DC-DC converter for energy conversion would be costly and unreliable. To address this issue, this paper proposes a method that involves the parallel connection of multiple DC-DC converters in coordination with supercapacitors on supercapacitor trams to achieve power balancing. The paper begins by developing a system model for the power supply system and explaining its motivation. Next, a design for a parallel connection of multiple DC-DC converters is presented to prevent excessive current in any one converter and achieve current balancing among them, thereby reducing the system load. Finally, a cooperative control method is proposed to achieve current balancing at each DC-DC converter. The proposed method’s effectiveness has been demonstrated through extensive experiments and simulations.