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This system uses a series-hybrid configuration that first converts the engine output into electrical power and uses only motors for propulsion. The AC output generated by the engine is converted to a VVVF AC supply by the main converter to drive the induction motors. Storage batteries are located on the intermediate DC section of the main converter, and the charging and discharging of the storage batteries is controlled using output adjustment of the converter and inverter.
The series-hybrid system allows the engine speed to be set irrespective of the vehicle speed, thereby permitting high-efficiency power generation by operating predominantly in the low fuel consumption engine speed range. This also reduces exhaust gases. The use of electric train inverter control technology allows the use of regenerative braking, and using regenerated energy temporarily stored in the batteries as auxiliary power for acceleration is expected to give fuel savings. An engine cut-out control is also employed to reduce noise when stopped at stations.
The series-hybrid system eliminates the need for equipment such as hydraulic transmissions, which entail high maintenance costs on conventional diesel trains. Similarly, commonality of equipment with electric trains saves maintenance labor and allows more efficient utilization of existing inspection equipment.