# 180kW wireless charging



## tomofreno (Mar 3, 2009)

The Korea Advanced Institute of Science and Technology (KAIST) and the Korea Railroad Research Institute (KRRI) have developed a wireless power transfer technology that can be applied to high capacity transportation systems such as railways, harbor freight, and airport transportation and logistics. The technology supplies 60 kHz and 180 kW of power remotely to transport vehicles at a stable, constant rate.

More at: http://phys.org/news/2013-02-wireless-power-technology-high-capacity.html#jCp


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## Ziggythewiz (May 16, 2010)

85% efficient from 20 cm. 

If they really just have to lay a couple wires in the road (as opposed to a charging pad every 2 feet) I suppose wireless charging in-route may just have a future.


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## dougingraham (Jul 26, 2011)

85% efficiency means 15% loss and 15% loss at 180kw is 27kw. That is a lot of waste heat!


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## njloof (Nov 21, 2011)

True, but average residential transmission loss (for home chargers) is 7% already...


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## dougingraham (Jul 26, 2011)

njloof said:


> True, but average residential transmission loss (for home chargers) is 7% already...


I think it is probably more than 7%. The losses in my charger is between 15% and 20%. I am not sure what your point is here because you would add the 15% on top of the charger losses. Can you explain what you meant?


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## njloof (Nov 21, 2011)

dougingraham said:


> I think it is probably more than 7%. The losses in my charger is between 15% and 20%. I am not sure what your point is here because you would add the 15% on top of the charger losses. Can you explain what you meant?


I pulled that number from a US gov website... that's the average loss getting the power to your home, before it even hits your charger. Assuming highways can be supplied from nearby power plants, the losses of capacitive charging don't seem that bad.


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## dougingraham (Jul 26, 2011)

njloof said:


> I pulled that number from a US gov website... that's the average loss getting the power to your home, before it even hits your charger. Assuming highways can be supplied from nearby power plants, the losses of capacitive charging don't seem that bad.


These averages are probably still going to apply to a charging system in a roadway. It will be less near the power plant and more the farther away you get.

The only way I can see this being an advantage (other than convenience) would be if you could improve the car by 15% by leaving out enough batteries to improve the overall vehicle efficiency by the same as the losses. And that isn't very likely.

Tesla has the idea. You put high speed charging stations in place along the highways often enough that when you stop for a necessary rest every couple of hours you can add enough to keep you going for another hour. Put in a couple of stations (to start) every 25 to 50 miles along the interstate system. A 100kw charger can put in around 5 miles per minute so a 15 minute quick stop would give an additional 75 miles. This really would not be that inconvenient. Increasing the cost of the electricity by 15% seems like a lot just to save a few 15 minute stops.


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## tomofreno (Mar 3, 2009)

dougingraham said:


> ...Increasing the cost of the electricity by 15% seems like a lot just to save a few 15 minute stops.


 So you are saying that fast charging is 100% efficient?


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## dougingraham (Jul 26, 2011)

tomofreno said:


> So you are saying that fast charging is 100% efficient?


Of course not. But you still have to have the charger electronics with the wireless charging so the 15% loss in the wireless is always going to be in addition to the charger losses. All the wireless piece does is replace the cord between the grid and the charger in the car with a 15% additional waste of power. I don't see the advantage of being able to move while doing this as enough. Think of it this way. For every $100 you spend on electricity $15 of it would be thrown away as heat. To me that is unacceptable. The losses in chargers are only a little better than this and it irritates me every time I think about it.


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## Duncan (Dec 8, 2008)

This was covered in a lecture series last year

http://www.diyelectriccar.com/forum...oad-technology-free-lecture-series-79394.html


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## palmer_md (Jul 22, 2011)

dougingraham said:


> Of course not. But you still have to have the charger electronics with the wireless charging so the 15% loss in the wireless is always going to be in addition to the charger losses. All the wireless piece does is replace the cord between the grid and the charger in the car with a 15% additional waste of power. I don't see the advantage of being able to move while doing this as enough. Think of it this way. For every $100 you spend on electricity $15 of it would be thrown away as heat. To me that is unacceptable. The losses in chargers are only a little better than this and it irritates me every time I think about it.


yes, but the point you are overlooking is that this is not an additional 15% loss all the time. I'd still plug in at home for charging every night, but I could also take a road trip with my EV and it only "costs" me 15% more than it would at home, and that is still better than taking my ICE on the road trip. Now I can have my EV as my only car. Hurray!

The way this beats the Tesla model is that I can drive around with a 25-30kWh pack in my car instead of the 85-100kWh pack that is needed for the Tesla model, and I can stop wherever I want on the trip and not just at the filling stations. Smaller packs mean cheaper cars and less weight means they will be more efficient...perhaps even 15% more efficient with the reduced mass of the car.

I agree that wireless charging in my own garage at home is just dumb. The 15% penalty for not using a cord at home is not smart.


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## Duncan (Dec 8, 2008)

The NZ version was 95%+

There are lots of advantages in wireless charging at that level

They had also developed an in road on the fly charging system - the remaining engineering problem was making it proof against 40 tonne trucks

The real trick appears to be making the magnetic field shape such that it can allow for a lot of misalignment


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## PhantomPholly (Aug 20, 2008)

The 15% charging losses utterly ignore the enormous capital outlay and increased maintenance costs for these magical free-charging roads. They were talking about this in the 1950's, and it's just as likely today as it was then.


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