Battery operated electric buses offer a cleaner, quieter ride and can save transit authorities huge sums of money over their lifetime. However, they suffer from the same drawbacks as all EVs i.e. limited range and high up-front cost. Integrating enroute charging into an electrified bus route can address both of these challenges. The ability to partially charge at a short stop along the route increases the effective range of a bus, and/or allows the battery pack to be smaller, saving on the purchase price of each vehicle.
In 2013, a Utah company called WAVE (Wireless Advanced Vehicle Electrification) demonstrated this concept with the Aggie Bus, a 20-passenger bus powered with a 20-25 kW stationary wireless charger, with efficiency greater than 90%.
The WAVE system uses a charging pad that lies flush with the pavement and is sturdy enough to be run over all day without damage. Another pad is mounted on the vehicle’s undercarriage 7 to 8 inches above. The WAVE system is designed to be unobtrusive – at the enroute charging site, the only visible component is a small interface box that houses circuitry between the pad and the grid connection. With the next-generation system, this box will be placed underground, for a completely invisible infrastructure. The WAVE system is easily adapted to buses from different manufacturers. The onboard components take up little space, and can be used in different vehicles with only minor modifications. The same in-ground charging pad is used for all vehicles, so it would be no problem for a transit company to operate different types of buses on the same route.
WAVE is a fully automated system that requires minimal or zero driver intervention. It can automatically detect pad alignment and initiate charging. There’s also a safety procedure that’s implemented in both software and hardware. If for some reason the driver were to pull away, or the bus were to roll back, the system would automatically and safely shut down. Storage is not necessary for operation of the system, which can pull 480-volt, 3-phase power directly from the grid. However, in places where there are utility demand charges, the company is seeing increasing interest in stationary storage, which would allow power to be drawn from a battery during the day.
WAVE currently has systems in operation in several cities. Its system is currently in operation with several vehicle types, from a 30-foot trolley to 40-foot buses, with different battery pack voltages, from different OEMs. So far, WAVE has sold its system only for transit vehicles, but is “vigorously exploring opportunities in other markets.” The system is designed to be scalable and adaptable to many different vehicle types.
• System keeps electric vehicles running for the entire day.
• Completely silent, reliable, and creates zero emissions.
• Requires zero intervention in driver in charging.