The electric car seems destined to be the car of the future and to derive electric energy from the
grid in a two-way exchange known as V2G (vehicle-to-grid). Ideally, the battery in every
parked electric will contribute to a vast energy storage system available to tide the grid over
periods of peak demand. Proponents claim this is economically sound and can substantially
reduce battery cost to the motorist. But will the motorist conscientiously plug his car in whenever
he parks, even if he knows his battery does not need topping up, even if he is in a hurry (as
almost everybody is), if it is raining, if he is disabled, or if his mind is on other matters? No, he
won’t. He may even forget to plug in when the car is in the home garage or carport. Of course
someone will come up with a way of making the connection to the grid automatically. One way
might be to have at the charging station a robotic arm that swings the grid connector over to the
parked car and plugs it in,
but that is expensive and easily vandalized--already a problem with charging stations and cables.
In a better solution the charging station reduces to a docking bay consisting simply of a
concrete curb with embedded metal contacts to engage with corresponding contacts underneath
the front end of the car when it was driven against it. In a demonstration model, a light came on
when contact was made. There were no connectors, only contacts that, unlike those within a
connector, needed no protective covering to make them safe. In the 1/30-scale model, the curb
contacts were energized from a small battery and were “hot” all the time. In the real world, they
would become hot only after a series of checks ensured that it was completely safe to energize
them. These checks would be made by the interaction of small computer-logic systems in the
curb and the car.
Safe, vandal-proof, inexpensive, inconspicuous, user-friendly, low-maintenance—these were the
obvious attributes. Nobody could think of any negatives. It was not without some trepidation that
the authors presented their model. It seemed so simple that surely there must be a catch and, if
so, this group of electrical engineers would surely point it out. But none did. The notion was new
to the experts, who came to this international meeting to reach a consensus on the design of
connectors for plugging in electric vehicles.[Read Full Article]
Charging via exposed contacts, not normally energized, could solve the V2G (vehicleto- grid) connection problem for battery electric vehicles. Exchange of harmless low-level signals, conforming to some prearranged protocol, could render this entirely safe for any conceivable circumstance. There are various means for causing the contacts to become energized. Below them there would be a relay or switching mechanism for turning them on. This, and the wiring to it, would be below the surface. To energize the contacts both in the vehicle as well as on the curb, the presence of a suitably equipped and authorized car must be recognized, either by wireless or direct contact, according to an authorizing code that could include billing information. The soundness of the connections and wiring both in the ground and in the vehicle would be checked before the contacts became hot. [Read Full Article]
