Urban Rail Transit Power System Integrated with Electric Vehicles Based on CLLC Resonant and Buck-boost Converter

In urban rail transit system, braking energy of trains is of large scale, but it has not been used sufficiently. Most of the energy has been wasted on resistors. To smooth the fluctuation of traction grid and reduce the loss, various energy feedback methods and energy storage devices are applied in the system. Accompanied by the development and popularity of electric vehicle (EV), the energy storage capacity of it can be used in urban rail system. In this study, a novel architecture combining electric vehicles with urban rail transit is put forward, which absorbs braking energy nearby. By applying cascaded power transmission unit based on CLLC bidirectional resonant converter and buck-boost non-isolation converter, orderly power flows are allowed and power supply is more flexible with a small volume and high efficiency.