Takeshi Mizuma

Frequency domain based power controller of energy storage device for a hybrid traction system in a DC-electrified railway

In the DC-electrified railway system that is fed by diode rectifiers at a substation, the substation cannot transmit DC electric power to an AC-grid. Hence, the electric power regenerated by a train should be consumed by other trains. Therefore, a regenerative brake cannot be used when other trains do not consume the electric power. In order to use the regenerative brake independent of the state of other trains, using energy storage device (ESD) for DC-electrified railway systems is examined in recent years. This paper deals with feeding line and electric double layer capacitor (EDLC) hybrid train system. This research aims at establishment of the design method of controlling electric EDLC power for using a regenerative brake for any conditions. In this paper, to smooth the power from the feeding line, the control method of EDLC power based on the frequency band of the motor power is proposed, and it is verified by the numerical simulation.

Technical challenges to realize energy-efficient linear metros in Japan

Subway operators introduced linear metros in 1990s and continued successful urban passenger transport service in many large and dense cities in Japan for more than a quarter century. A significant disadvantage of the linear metros is the relatively low energy efficiency. Therefore, Japan Subway Association (JSA) started a technical challenge to reduce the traction energy consumption of linear metros in 2012. After engineering efforts for three years, the improved automatic train operation (ATO) achieved the energy-saving of more than 16%. This paper technically explains the idea and the concrete methods in the successful technical challenge.