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Gov't Researchers Develop Wireless Car Chargers That Are Faster Than Plug-ins (computerworld.com)
An anonymous reader quotes a report from Computerworld: The U.S. Department of Energy has demonstrated a 20,000 watt (20KW) wireless car-charging system that offers three times the efficiency of today's plug-in systems for electric vehicles (EVs). The research is the first step in creating a 50KW wireless charging system that may someday allow roadways to charge vehicles while they are being driven. The DOE's Oak Ridge National Laboratory (ORNL) in Tennessee demonstrated the new system in partnership with Toyota, Cisco Systems, Evatran and the Clemson University International Center for Automotive Research. ORNL said the 20KW charging system for passenger cars is the world's highest power wireless system. It was developed in less than three years using a "unique architecture that included an ORNL-built inverter, isolation transformer, vehicle-side electronics and coupling technologies."
TFA states 90% efficiency at 3x the rate, bad summary is bad
Who said a MRI is dangerous? Thousands of people have them every day with no increase in cancer risk.
If you bring a large chunk of metal in to the room then sure it's dangerous but that's more to do with the metal flying physically towards a magnet rather than cancer.
Yes yes, terrible summary.
The 'fun' part is the 10% coupling waste (versus I would imagine much less than 1% for plugin charging).
Remember, we are not talking about the battery charge efficiency here, their 10% is just for the transfer of power to the car..
So, thats 'only' 2kw continuous loss. Thank god everyone is converting their houses to LED lighting, which still wont
offset the losses here.
Go Progress!
No matter how many times more efficient a new tech is; It will never reach or exceed 100% efficiency, because thermodynamics and math say no.
To be 3X as efficient is defined as saying the loss rate is
So at 90% the charger has a loss of L
Thus, if it is 3-times as efficient, then the loss rate is L = 96.66667% * j.
A Tesla charger has an efficiency of over 90%. If this charger has an efficiency three times that, then it should be above 270%. Maybe it can feed the extra 170% back into the grid.
The article poster mis-quoted the article. The article actually states: "achieved 90 percent efficiency at three times the rate". So it is the same efficiency as the tesla, but it charges three times as fast.
You do realise that inside many DC-DC converters, and indeed inside all of the power transformers between the power station and your house, there are magnetically coupled coils that effectively transfer the energy "wirelessly".
The difference in this case is using an air cored coil at a greater distance. It's definitely harder to make them efficient but they have clearly shown great potential here, with 90% efficiency versus DC-DC converters at 95% and regular transformers at 98%.
Not MRIs. When I did a paediatric anaesthesia fellowship we would routinely sit in the room for the scan. Think cardiac MRIs requiring breath holds. The techs sit outside the room cause they need to use computers to run the scanner and also it's really (unpleasantly Even with quality ear protection) noisy. Plus something about pressure in the room that I never understood.
Tesla chargers are 120kW, and the more common CHAdeMO used by the Nissan Leaf is 50kW in it's currently deployed form. So if they can get up to 50kW they will have matched currently available wired technology, except that 50kW is not really enough and will be replaced by 100kW+ chargers in the next few years.
Rapid charging needs to average about 30 minutes per charge to be useful. So that means charging at 1.5C, i.e. 2x the capacity of the battery plus some extra for losses. 30 minutes is the average, if you arrive with 1% charge it will take 45 minutes but most people arrive with at least 20-30%.
The minimum battery capacity for a mainstream vehicle seems to be about 60kWh, which will give you a solid 200 miles range under realistic conditions with some margin for safety. So the charger needs to be at least about 100kW to hit the 1.5C + losses target. That's why Tesla supply 120kW.
This misses the point of wireless charging though. No need to plug in, just install it in car parking spaces and let the car charge for an hour or two while you go round the shops. 20kW is actually already quite adequate for this. I regularly charge at 7kW when shopping.
const int one = 65536; (Silvermoon, Texture.cs)
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