Study of bidirectional DC-DC converter for power management in electric bus with supercapacitors

Electric bus with supereapacitors (SCs) as the only on-board power source could realize fast and effective recuperation of energy in frequent braking and deceleration in city. However, it's a very challenging task to design a bi-directional DC-DC converter because of wide voltage range and high current order of SCs. This paper presents an analysis and comparative study of several non-isolated bi-directional DC-DC converters. As a compromise of power density, cost and reliability, Buck/Boost converter is adopted as the final choice. Furthermore, a soft-switching circuit with snubber is designed and realized to reduce EMI and losses in switching devices. Experimental results show its high continuous-running efficiency and reliability, which could satisfy the requirements of this power-management application.