A cooperative charging strategy for onboard supercapacitors of catenary-free trams

In this paper, a cooperative charging strategy is proposed for onboard supercapacitors of catenary-free trams. The multi-module charging system consists of n buck converters connected in parallel. The parallel-input parallel-output (PIPO) charging system is modeled mathematically using the averaging method. A cooperative constant-current charging control strategy is designed using the leader-follower consensus approach, where the virtual leader represents the desired charging current for each charging module with a warm-start mechanism. The cooperative charging approach provides dual benefits of both excellent dynamic performance and good reliability. Simulation and experiment results are provided to illustrate the effectiveness of the design.