While EV charging isn’t that tedious with a cable, for quick trips, being able to just park and have your car automatically charge would be more convenient. Researchers from Oak Ridge National Lab (ORNL) and VW have moved high-speed wireless EV charging one step closer to reality.
We’ve seen fast wireless EV chargers before, but what sets this system apart is the coil size (~0.2 m2 vs 2.0 m2) and the fact it was demonstrated on a functioning EV where previous attempts have been on the bench. According to the researchers, this was the first wireless transfer to a light duty vehicle at 270 kW. Industry standards currently only cover systems up to 20 kW. Ac Wallbox Ev Charger
The system uses a pair of polyphase electromagnetic coupling coils about 50 cm (19″) wide to transfer the power over a gap of approximately 13 cm (5″). Efficiency is stated at 95%, and that 270 kW would get most EVs capable of those charge rates a 50% bump in charge over ten minutes (assuming you’re in the lower part of your battery capacity where full speeds are available).
We’ve seen some in-road prototypes of wireless charging as well as some other interesting en route chargers like pantographs and slot car roads. We’ve got you covered if you’re wondering what the deal is with all those different plugs that EVs have too.
Well damn, 95% seems incredibly good. But at 270kW that’s still 13,5kW wasted (heat induced somewhere else?).
Yeah, that’s more than my entire house is typically using… that’s a lot of heat – 4 electric fires – wasted, or worse, heating the battery.
But how does it compare with wired charging? Those cables get hot when 270kW is passed through them. They either have to be water cooled or limit the 270kW charging period.
A quick search shows that 350kW wired charger manufacturers are claiming up to 96% efficiency, so only 1% better than this.
they calculate that efficiency compared to cable :)
1. That’s still an incredible efficiency loss. It’s already going to require doubling electrical infrastructure to replace ICE . . .
2. 5 inches isn’t a practical ground.clearance off a track. So there’s going to need to be moving parts here – greatly increasing costs and lowering reliability – at which point, why not just make metal-metal contact and skip the ‘wireless’?
And then imagine the shielding for electronics needed.
because with wireless you don’t have to park in exactly the same spot everytime, you can be off a bit and still get the vehicle charged
Off a bit means huge efficiency losses, try that with your phone charger. So we got: – 13 cm = need for rising pedestal under the car – need to align car or pedestal perfectly – hauling heavy fragile coil under the car at all times – still losing over 10kW, probably half of it heating up that coil meaning now we need to actively cool it on the car side = even more losses
Well yeah, it seems ridiculous to waste that much power for the sake of ‘convenience’ when just plugging the damn things in which would charge faster as well.
More likely 50% efficiency over 13cms. Scam.
Is there anywhere in that advertisement a hint t what the charging system looks like and what it costs?
But overall, I don’t really believe in this. It’s too much effort and complexity for too little gain.
I think the way forward is to go to a swapable battery system. First, it allows a battery to be swapped in about the same time as it takes to fill a tank of gasoline, and as a result battery capacity for long trips is no worry anymore.
It also solves the resale value for 2nd hand vehicles. Now, second hand electrical vehicles devaluate quickly, because it is prohibitively expensive to replace a worn out battery. If a battery is worn out, the rest of the car is pretty much waste (or “spare parts”).
Because of the cost of batteries, new electric vehicles are also quite expensive. If you don’t have to buy a battery together with the vehicle, then cost would go down a lot (How much?)
I just saw “Why Battery Swapping Is A BAD Idea” from youtube / AutoTrader, and it’s a quite stupid video. Most what he mentions are non arguments or solvable problems, such as the “chicken and egg” thing. Of course the batteries have to be universal, so they work for each car “brand” (how many car brands are left, except for the different names?) For the rest, it boils down to car manufacturers do not want to be responsible for the batteries, so they much rather sell one together with a car, then to set up a charging network.
He also mentions about 5 different systems that exist (or have existed) for battery swapping, which is of course part of the problem. There should not be 5 different systems.
They already have battery swapping in China, which makes watching a stupid video about not doing it, even more pointless.
95% isn’t bad at all. But that doesn’t mean it is a good idea, think about it: 5% of a 270kW is 13.5kW wasted! You could light 2700 5Watt LED lights from that, that’s a lot of light! Plus the additional electronics required to pull this off and for what, so that somebody doesn’t need to push a plug into a socket?!?! Sure the idea is awesome from a technical perspective and as an engineer I really dig the concept. But should technology choose this path?
There’s one positive, the parking spot is always dry when it rains and without snow during winter (assuming people are frequently using it). Can’t wait to see what fun tricks can be pulled with aluminum foil or loops of wire, wait for people to park their car, initiate charging and then the fun starts…
For those above who don’t know about how EV charging works, you must know that no charging can occur before there a long and painful communication (search for ISO/IEC 15118). So there is no way to get an “aluminum foil or a loop of wire” in the way without being detected first.
The charging system will only provide the amount of current the charged system is able to accept. So, no, you won’t get 270kW of EM energy on your car simply because your car can’t accept it. Thus the 5% loss (which, by itself is meaningless) isn’t 14kW because the actual current transferred will be a lot lower.
Also are the losses on the charger or the vehicle? Half-Half? 80/20?
If it’s 50% on the charger side (likely more), then it’s currently what you have in the AC/DC charging station that are installed on the road. That’s why you ear that loud fans when you plug your car. Converting close to a MW of AC to DC, even at 95% efficiency give a huge amount of heat to dissipate. On a RF energy transmission, you *might* skip this step since you might use AC current for the coils.
In the end, this system might end up being more efficient that the braindead cable that doesn’t scale well for hundred of amps (if you have ever tried to manipulate a 25mm2 cable, you know what I mean).
In cold temperatures, maybe have those fans direct the heat under the car, so the batteries are warm enough to accept the charge, so stalled Teslas won’t pile up during Chicago blizzards.
Another possible win is that EM could more easily be made agnostic to brand (whereas a cable will have a brand/model-related voltage)
I like the idea of going direct from AC to AC (even though the second AC might be riding at a 100Hz amplitude).
Please be kind and respectful to help make the comments section excellent. (Comment Policy)
This site uses Akismet to reduce spam. Learn how your comment data is processed.
Dc Fast Charging Station By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more