ABB has developed a new boost-charge technology that will help power what it claims is “the world’s first” high-capacity, flash-charging electric bus system, with no overhead cables necessary. The Zurich, Switzerland-based power and automation technology company announced at the International Association of Public Transport congress in early June in Geneva that it is working together with the city’s public transport company (TGP), the Office for the Promotion of Industries and Technologies (OPI), and the Geneva power utility SIG on the TOSA (Trolleybus Optimisation Systeme Alimentation) electric bus system pilot project.
The new boost-charging technology will be deployed for the first time on a large-capacity electric bus that can carry up to 135 passengers. The bus will be charged directly at certain stops with a 15-s energy boost, based on a “new type of automatic flash-charging mechanism” according to ABB, while the passengers enter and leave the bus. Rapid battery charging takes place at every third or fourth bus stop along the pilot project’s route, which runs between Geneva airport and the city’s international exhibition center, Palexpo.
Charging stations of different sizes are available to suit the specific bus stop.
“Through flash charging, we are able to pilot a new generation of electric buses for urban mass transport that no longer relies on overhead lines,” Claes Rytoft, ABB’s acting Chief Technology Officer said in a statement announcing the technology. “This project will pave the way for switching to more flexible, cost-effective, public transport infrastructure while reducing pollution and noise.”
The flash-charging technology and the onboard traction equipment used in this project were developed by ABB and optimized for high-frequency bus routes in key urban areas, carrying large numbers of passengers at peak times. Onboard batteries can be charged in 15 s with a 400-kW boost at select stops. At the end of the bus line, a 3- to 4-min boost fully recharges the batteries.
An “innovative” electrical drive system enables energy from the roof-mounted charging equipment, along with the vehicle’s braking energy, to be stored in compact batteries and to power both the bus and its auxiliary services, such as interior lighting.
(See tables, at top right, detailing technical specifications for both the electric bus and its infrastructure.)
TOSA is a zero-carbon-emissions project; the electricity used reportedly comes entirely from clean hydropower. The 15-s charging time does not interfere with the bus schedule, and the system offers aesthetic and operational benefits, too: the elimination of overhead lines not only reduces visual clutter in the urban landscape but also provides greater route flexibility.
The system uses a laser-controlled moving arm, which connects to an overhead receptacle for charging at bus shelters, instead of the usual trolley poles to overhead lines. ABB leveraged its expertise in the rail industry sector to move the technology into the public mass transportation sector.
There are two main reasons why this has not been done before, according to Bruce Warner, Electrical Engineer Research and Development at ABB. “You really need to do a quick connection, so that you don’t waste time making your connection when you want to do the charging. That’s been a real innovation in this project—that we’ve come along with something that connects more quickly than anybody else has been able to do.”
The second reason is advancement in battery technology that allows fast charging, said Warner.
An ABB video offers more insight into the system’s development and implementation: http://www.youtube.com/watch?v=c-Fg94A2Vko&feature=youtu.be.