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Power-User

Join Date: Jan 2007
Location: Heidelberg, South Africa
Posts: 125
Good Answers: 10

Wireless EV Charging Efficiencies

04/11/2016 8:18 AM

Just saw the link today on IHS News, titled "This Wireless Charging System is 90% More Efficient Than Current EV Options"

http://electronics360.globalspec.com/article/6527/this-wireless-charging-system-is-90-more-efficient-than-current-ev-options

Now the title was rather intriguing and optimistic-sounding, but then, as expected, the second sentence folded it: "The team has just demonstrated that its 20-kilowatt system has achieved 90% efficiency at three times the rate of the plug-in systems that are commonly used for electric vehicles today." I read it as meaning simply that the system is 90% efficient, just at very high charging rates. Not sure from where to where the efficiency was measured, but still, rather tame. Ah, just a timid little rant, but reporters should get their stats correct.

It got me thinking, though - as the use of EVs increase, such inefficiencies would cause a rather significant waste of power. In this case, a 20kW charging system (sorry, i usually think in kVA terms) would have 10% or 2kW losses - the equivalent of keeping a kettle boiling for the time you're charging. With the drive to energy efficiency, surely that must be minimised to levels closer to the 99% or whatever a traditional cable gives? Maybe this is the price lazy people are willing to pay? Being such a new field, are their standards for this yet?

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Guru

Join Date: Jan 2008
Location: Tucson, AZ
Posts: 873
Good Answers: 23
#1

Re: Wireless EV Charging Efficiencies

04/11/2016 7:52 PM

Yep, there will always be the physical 'distance' problem due to the "Inverse Square" Law coupling.

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Power-User

Join Date: Aug 2008
Location: Melbourne, Australia
Posts: 476
Good Answers: 32
#2

Re: Wireless EV Charging Efficiencies

04/11/2016 11:03 PM

I read it as a system that also included the actual AC to DC charger and charge controller. So the 90% shapes up pretty good as compared to a conventional wired EV fast charger. Not quite as easy to implement though as you would also need a wired input for not-at-home/work charging. More weight to carry around as well.

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