Since 2000, Railway Technical Research Institute has pursued the development of vehicles with power sources based on clean, low-noise fuel cells that discharge only water as a replacement for diesel cars and the like (Fig. 1). Accordingly, our Institute developed a prototype lithium-ion battery that absorbs regenerative power and outputs driving power during powering, and produced chopper apparatus to perform charge/discharge control of battery power. Using these technologies, hybridization with fuel cells was achieved.
The prototype lithium-ion battery has 168 cells (30 Ah) parallel-connected in two rows, and is capable of absorbing up to 360 kW of regenerative power. The chopper apparatus for charge/discharge control of battery transmits and receives control signals to/from all apparatus connected to the main circuit, and conducts power control between the fuel cells and the battery (Fig. 2).
The RTRI carried out running tests in our test line with our hybrid electric test trains. The control types conducted involved battery charging from fuel cells during stoppage, running on battery power (and fuel cells) during acceleration, battery charging during deceleration from regenerative braking power, and battery charging from the fuel cells during deceleration by air brake. The results showed that the two-train-set vehicle could run without a supply of electric power from catenary system (Fig. 3).