Potential applications of Thermoelectric generation in the electric train

초록

In order to increase the energy efficiency of electric trains, various energy harvesting technologies have been researched and deployed in the electric trains. In this study, we introduce potential applications of thermoelectric generation (TEG) in the electric trains and suggest a few conceptual designs for the train’s components in which TEGs can be applied. One of the applications suggested here is the train propulsion system combined with TEG. In general, the conventional train propulsion system consists of inverters, filter reactors, and traction motors, which dissipate about 5 % of total traction energy as heat losses. However, water-cooled designs for the components make it possible not only to improve its capacity but also to harvest a certain amount of electric energy by TEG modules equipped in the heat-exchanger of cooling system. Other applications are TEG-embedded train braking systems. Most electric trains use regenerative braking system that converts the motor into a braking generator when decelerating the trains. In the ideal operation, up to 70 % of the traction energy can be returned to train power substations, but 20~30 % of the energy is still dissipated as heat at mechanical brakes or over-current resistors in the train control units. Therefore, additional energy harvestings by TEG modules can be expected at the mechanical brakes and the resistors. The efficiency of TEG modules has been still one of critical issues in deploying them to industrial application. Finally, we suggest the minimum performances of TEG modules to be economically deployed in the electric trains.