Traction Energy Storage System with SCiB™
For DC Railway Power Supply Systems

Toshiba's Traction Energy Storage System (TESS) with SCiB™ is a new energy saving solution with Toshiba's own battery technology of high quality.

When a train set is braking, it generates energy which can be used by the adjacent accelerating trains. But in most cases, this regenerative energy is not efficiently utilized by the next train and is wasted as heat through onboard or wayside resistors. Such cases does not only incur energy wastage but also likely to cause abrupt shift from regenerative braking to mechanical braking. This sudden change may further cause passenger ride discomfort and degradation of the brake shoe due to abrasion.
Toshiba's Traction Energy Storage System efficiently stores surplus regenerative energy in the SCiB™ and discharges it to another accelerating train. TESS is installed with Toshiba's patented advance control system which allows flexible control of charge-discharge cycles in accordance to the battery's State-of-Charge (SOC). This allows significant increase in battery lifetime.

Key Benefits

Advanced V-SOC Battery Control

Toshiba implements an advanced Charge-Discharge algorithm for the efficient control of TESS.

For conventional energy storage systems, battery is charged and discharged to keep specified SOC (State of Charge). Thus, battery is charged and discharged regardless of the feeding voltage.
There will be instances when the battery will be unnecessarily charged/discharged even at rated line voltage (area between the Charge Start Voltage and Discharge Start Voltage). Thus causing feeding voltage imbalance and shortened battery lifetime.

As for Toshiba's advance V-SOC control method, charge and discharge characteristics automatically shifts depending on SOC. When SOC is high, charge-discharge characteristic will shift to the higher voltage side, hence the battery shall be easily discharged. On the other hand, when SOC is low, charge-discharge characteristic will shift to the lower voltage side thus, battery shall perform more charging.

The lifetime of a battery strongly depends on the charge-discharge times and current. By using this control algorithm, unnecessary charge and discharge can be greatly reduced.

Toshiba's system does not define any certain SOC which means that charge and discharge will be performed dynamically within a wide range of SOC.

[Patented]

• *SOC : State-of-Charge *V-SOC : Voltage-State-of-Charge