Running characterization of LRV powered by hybrid of lithium ion battery and super capacitor

Recently, the rechargeable battery and fuel cell have been applied on the running of railcar and LRV. Lithium ion battery is expected as one of the best driving source of them because of highest energy density and power density among the rechargeable battery. At present, VVVF inverter type railcars and LRV are used as the main regenerative braking systems to convert kinetic energy of them into electricity that is fed back into the overhead contact wire. Although the VVVF inverter has also been used for railcars to improve energy savings while running, the regenerative energy is often lost when the other railcar is not routed on the same line. The use of an LIB is anticipated to solve this problem. However, when the regenerative energy is charged to lithium ion battery for short period, it is considered that the lifecycle of it will be reduced. In this work, VVVF inverter type LRV which is driven with lithium ion battery and super capacitor was developed to reduce the load of lithium ion battery during the charge of regenerative energy by using the super capacitor. 60 kWh of Mn type lithium ion battery was used. The running test was carried out at the winter to examine the performance of lithium ion battery at lower temperature as well. The running performance of LRV and energy-saving effect were examined. The relation between running time and voltage, current and integrating watt was investigated in detail. LRV was run when the lithium ion battery was discharged between 660 V and 480 V. On one charge, the LRV could run at about 40 km. The mileage of LRV improved 22 % by charging the regenerative energy with regenerative braking system. Furthermore, it was confirmed that the mileage of LRV improved about 10% by using super capacitor and the temperature rise of the lithium ion battery was reduced.