|The New Energy Train.|
East Japan Railway Co (JR East) is developing a new diesel-electric series hybrid railcar that it will introduce into operations next summer. The diesel hybrid, complete with lithium-ion battery and regenerative braking, is a precursor to a planned fuel-cell hybrid traction system.
One of the key design factors for the hybrid was the ability to deliver grade ability at the same level as that of a new model railcar. To ensure that level of performance, the JR East engineers opted to use twin 95 kW motors that have a good track record in electric commuter cars, along with a 330 kW diesel engine powering a 180 kW generator.
|The powertrain of the hybrid railcar.|
In calculating the battery requirements, the JR East engineers factored in capacity for storing regenerative braking energy (the average braking energy used for making a single stop is approximately 1 kWh) and the electric energy necessary to run a railcar for 5 km between stations (approximately 3 kWh).
As an operations strategy (managed by a engine control unit JR East designed), they decided to use the battery within a state of charge (SOC) range of 20% to 60%. Taking all that into consideration, they chose a lithium-ion battery pack with a capacity of 10 kWh.
The railcar hybrid has six modes of operation:
Departing from a station: The car is set into motion on battery power up to a speed of 30 km/h (19 mph).
Cruising on a level track: The diesel engine operates at its highest efficiency, and a secondary battery discharges/charges depending on running loads.
Running up a slope: The diesel engine operates at its maximum output level.
Running downslope: The battery is charged by the regenerative brake. Car speed is controlled by the engine exhaust brake.
Braking: The diesel engine stops and the battery is charged by the regenerative brake.
Stopping at a station: The diesel engine switches off. Service energy is supplied from the battery.
|Engine management and control system.|
JR East says that the hybrid reduces fuel consumption by more than 10% compared to the current diesel railcars, while cutting NOx and PM about 60%. (Initial targets were a reduction in fuel consumption of 20% and reducing emissions by 50%.) The company has confirmed the performance even in difficult conditions, such as on steep slopes and in severe cold.
JR East will start to operate the hybrid train on the Koumi Line between Obuchizawa Station in the town of Obuchizawa, Yamanashi Prefecture and Komoro Station in the city of Komoro, Nagano Prefecture.
|The planned evolution of the hybrid powertrain. Click to enlarge.|
The company designed the powertrain in anticipation of replacing the diesel genset with a fuel-cell system.
Research is also underway to develop a hybrid-type next-generation streetcar, or light rail transit (LRT). The Railway Technical Research Institute of Tokyo will try to complete it by the end of March 2008.
JR East Technical Review: “Development of an NE Train”