05-01-2009, 01:22 PM
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Researchers Develop 'Smart Controller' to Manage EV, Plug-In Charging
As more and more automakers commit to building plug-in hybrid and rechargeable battery-electric vehicles, so grows the need to connect them to the power grid in an intelligent, economical manner
So-called smart charging will enable the vehicles to communicate with the grid to determine when electricity rates and demand are lowest and when demand is increasing - because of a heat wave, for instance - brownouts are threatening and it is time to "unplug' for awhile until things cool down.
Most of that's going to happen at night, when car owners are in bed and unable to monitor goings-on on the grid. So it will have to happen automatically.
Developing a system, or systems, to do all that has consumed a lot of R&D time and money over the years, but now research scientists at the federal Energy Department's Pacific Northwest National Laboratory in Richland, Wash., say they've come up with an inexpensive, portable and easy-to use controller that will do the job, and then some.
With a rechargeable vehicle plugged into the controller and the controller plugged into the grid via a common wall outlet, PNNL's device will automatically begin the charging cycle when electricity rates are lowest and monitor demand on the grid to ensure that the car isn't sucking in juice when it is high demand.
It can even sense when brownouts are imminent and temporarily shut down the charging process until the period of heavy demand passes.
It will take awhile to get to this point, but if, say, a million EV and plug-in hybrid owners in the Chicago area all got home from work around 6 pm and plugged their cars in for a recharge, "it could cause a major strain on the grid," PNNL engineer and project leader Michael Kintner-Meyer told Green Car Advisor in an interview Thursday.
The national lab's smart charger controller "could prevent those peaks in demand and enable the grid to be used more evenly" by delaying the start of recharging until late at night when demand for power from other sources had diminished, he said.
Regular use of the controller to ensure that a car charged its batteries only during a utility company's lowest rate periods could save the average EV or plug-in hybrid owner $150 a year, he said
Kintner-Meyer said his team of five researchers has been working on the device for about 15 months.
The project was launched after the lab issued a research report in late 2007 that said that if equipped with an intelligent load monitoring and time-of-day charging controls, the national power grid had the technical potential to support the demands of about 160 million electric vehicles before additional generating capacity would be needed.
"That report made us decide to take the next step and develop the charging controller that we said would be needed," Kintner-Meyes said.
The team's smart controller has been designed to be owner-programmable so each person could set the controller to begin charging a plugged-in vehicle at a specific time or at a specific price. Charging by time-of-day pricing would require participating utilities to broadcast power prices in real time so the controller's low-range wireless receiver could collect and process the information.
The device also is equipped to read demand swings on the grid when it is plugged-in, Kintner-Meyer said. That enables it to sense "stress conditions" and to temporarily stop charging the vehicle when the grid needs the power to satisfy other demands.
The instant reduction in charging load, if multiplied on a large scale because a large number of battery vehicles were being recharged at the same time, could serve as a sort of power grid shock absorber, rapidly diminishing demand to give grid operators the valuable minutes needed to bring additional power generators on line to stabilize things.
As a national lab, PNNL doesn't commercialize technologies it develops, but rather licenses them to private companies or other users.
Kintner-Meyers said the smart controller could be used by automakers or by charging station manufacturers, possibly as part of a so-called "smart cord" system in which the controller would be built into a portable charging cord that would connect a vhicle's battery pack to the charger or wall plug.
"That way," he said, "it would always be available, whether you were charging at home or while on the road or at work or shopping."
He said he sees the PNNL smart controller eliminating the need for individual automakers to have to come up with a standardized technology for building charging controllers directly into their electric and plug-in hybrid vehicles.
"We're going to start seeing these vehicles by 2011," he said, "and this is a technology that's ready to use, now."
Check out these videos:
Kintner-Meyer explains grid management and how the smart controller works