120-kW Wireless Charging Proves 97% Efficient

OCT 21 2018 BY MARK KANE 52

High power wireless charging efficiency reaches 97%.

The Department of Energy’s Oak Ridge National Laboratory (ORNL) upgraded its previous 20 kW wireless charging system to 120 kW, and through a new design and a silicon carbide power electronic device, it was able to achieve 97% efficiency.

Demonstration of the new system was done at a 6-inch (15.2 cm) air gap, which means that electric cars could recharge almost as efficiently as in the case of wired charging.

The next steps of the research will be:

  • 200 kW
  • eventually 350 kW
  • refining dynamic wireless charging technology
Researchers demonstrated 120 kilowatt wireless power transfer at the National Transportation Research Center, a DOE Office of Science User facility at Oak Ridge National Laboratory. From L-R: ORNL’s Saeed Anwar, Burak Ozpineci, Gui-Jia Su, and David Smith; DOE Vehicle Technology Program’s Lee Slezak; ORNL’s Veda Galigekere, Omer Onar, and Jason Pries. (Source: ORNL)
5 photos
State-of-the-art power electronics manage the safe and efficient flow of electricity among the system’s components. (Source: ORNL) ORNL researchers used computer simulations to design coils that generate the magnetic field required for wireless power transfer. (Source: ORNL) ORNL’s unique wireless coils and power electronics are co-optimized to safely transfer large amounts of electricity across an air gap at 97% efficiency. (Source: ORNL) ORNL’s unique wireless coils and power electronics are co-optimized to safely transfer large amounts of electricity across an air gap at 97% efficiency. (Source: ORNL)

Press release

ORNL demonstrates 120-kilowatt wireless charging for vehicles

OAK RIDGE, Tenn., Oct. 19, 2018—Researchers at the Department of Energy’s Oak Ridge National Laboratory have demonstrated a 120-kilowatt wireless charging system for vehicles—providing six times the power of previous ORNL technology and a big step toward charging times that rival the speed and convenience of a gas station fill-up.

The wireless system transfers 120 kilowatts of power with 97 percent efficiency, which is comparable to conventional, wired high-power fast chargers. In the laboratory demonstration, power was transferred across a six-inch air gap between two magnetic coils and charged a battery pack.

ORNL researchers created and demonstrated the world’s first 20-kilowatt wireless charging system, which is being modified for applications such as commercial delivery trucks.

“It was important to maintain the same or smaller footprint as the previous demonstration to encourage commercial adoption,” said project lead Veda Galigekere of ORNL’s Power Electronics and Electric Machinery Group.

“We used finite element and circuit analyses to develop a novel co-optimization methodology, solving the issues of coil design while ensuring the system doesn’t heat up or pose any safety issues, and that any loss of power during the transfer is minimal,” he said.

To achieve 120 kilowatts, the ORNL team created a new coil design co-optimized with the latest silicon carbide power electronic devices for a lightweight, compact system.

The system’s architecture takes energy from the grid and converts it to high-frequency alternating current, which generates a magnetic field that transfers power across a large air gap. Once the energy is transferred to the secondary coil, it is converted back to direct current and stored in a vehicle’s batteries.

The demonstration advances DOE’s extreme fast-charging goal to develop a system that delivers 350 to 400 kilowatts and reduces the charging time for electric vehicles to 15 minutes or less.

“This breakthrough significantly advances the technology needed to encourage greater adoption of electric vehicles by increasing their range and the ease of recharging, and in turn supports an energy-efficient mobility system for the nation’s economic success,” said Moe Khaleel, associate laboratory director for Energy and Environmental Sciences at ORNL.

ORNL researchers will explore innovations to increase power transfer level to 200 and eventually 350 kilowatts, while refining dynamic wireless charging technology. A dynamic system enables the automatic charging of electric vehicles using wireless charging pads installed under roadways. Higher power charging systems are needed to minimize the cost and complexity of dynamic charging. “The goal is dynamic charging at highway speeds,” Galigekere said.

The research was funded by DOE’s Vehicle Technologies Office (VTO) and performed at the National Transportation Research Center, a DOE user facility at ORNL. The VTO, part of DOE’s Office of Energy Efficiency and Renewable Energy, invests in early-stage research to enable private-sector development and commercialization of affordable, energy efficient transportation technologies that can strengthen energy security, support U.S. economic growth, and offer consumers and businesses additional transportation choices.

ORNL is managed by UT-Battelle for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov -by Stephanie Seay

Source: ORNL, Green Car Congress

Categories: Charging

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52 Comments on "120-kW Wireless Charging Proves 97% Efficient"

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120 kW real world charge rates would be a great thing for non-Tesla BEV’s. If you can charge for 20 minutes and get almost 40 kWh/140 miles of highway miles… That is a nice rate of charge.
But how many non-Tesla BEV’s can charge that fast this year? Next year? Nissan and GM have to up their game.

That is how I see it, two hours at 70 mph then 20 minutes charging.

Since SparkEV is capable of 0 to 80% in 20 minutes, only thing remaining is to have it go 2 hours at 70 MPH (currently 45 minutes with SparkEV to 80%). Bolt with 3X bigger battery could’ve been it, unfortunately it’s not due to slow charging.

A bolt with a 180 kWh battery (3 x 60). It would need a trailer or no back seat.

You’re reading it wrong. Current Bolt (60 kWH) with 3X bigger battery than SparkEV (18 KWH) that can charge like SparkEV would drive 2 hours at 70 MPH and charge to 80% in 20 minutes. But Bolt does not charge like SparkEV.

Except that this hypothetical fast-charging Bolt would be bigger, heavier, and more expensive than the one actually existing.

Yeah, getting the SparkEV to charge to 80% in just 20 minutes sounds great. Until you find out that it had just a 21.3 kWh pack so it was going from 0 to 17.1 kWh, which is about the same rate, 50 kW, as a Bolt, which you say is “slow charging”.
Having a tiny battery that charged at 50 kW doesn’t make the SparkEV good, it means that its tiny pack is less bad than it otherwise would have been. The pathetic thing about the SparkEV is that the battery capacity went down in 2014, to just 19 kWh.

You are confusing capacity (kWh) with charging ability (C rate). Imagine if Bolt (3X bigger) charged like SparkEV (1X). Then it’d be capable of 150 kW charging all the way to 80%, not taper at 50% (or 20%) like Tesla. And Bolt can certainly drive 2 hours at 70 MPH. Then a Bolt that’s capable of charging like SparkEV meets the criteria of 2 hours at 70 MPH, 20 minutes to charge. Assuming, of course, there are 150 kW chargers for it.

I am not confusing C rate with pack capacity. C rate is useful, but total pack capacity is critical in a lot of ways, from total AER, to max draw and to when (how many miles of AER) the charge taper kicks in. A small battery (like the Spark EV has) is useful in that it is a cheap gateway drug to get people to try a BEV for a city car. But a 21 kWh pack is too small to roadtrip with even if it could charge at a 150 kW charge rate. That having been said, I would agree with you that the C rate of the Spark EV is a good goal for larger packs to aspire to. A better C rate on the Bolt, and a more generous taper point, would make it a more attractive vehicle. I have to admit that after following the Volt for 11 years and owning one for 5+ years, I have pretty much written off GM cars. Every one of them has a fundamental flaw that makes them less than outstanding for a significant portion of the car buying population. The EV1 was absurdly expensive to build, so they never… Read more »

If you just put three SparkEV batteries into another vehicle, it would be so large and heavy that you wouldn’t get nearly three times the range. Increasing the size of low-density batteries gets diminishing returns.

I think Tesla should change to this if it’s commercially viable. Much better than plugging in or robot arms.

More importantly, it’s a heck of a lot better than a gas pump.

Imagine a world where a “charging tile” is embedded in each parking spot. Since cars spend most the day parked, you’d never have to think about recharging. (except when on long trips).

Sounds far fetched? Just over a century ago it would be unthinkable that all streets and major roads and parking lots are illuminated. Or that almost every household owns at least two cars. Or…..

Wireless charging is more convenient, the spots that have it could get more business.

Like in this vision. (Weird music playing, probably for copyright reasons)

Very impressive! I’m a huge fan of dynamic charging. I still prefer a wired approach for higher charge rates at much lower cost, but wireless is definitely sexier. ORNL’s work gets wireless back into the conversation.

Good job guys!

Read between the lines: They are saying that losses go down as frequency goes up.

Only to a certain degree. I studied and built wireless charging for biomedical implants, and while the key metric of Q-factor in a coil goes up linearly with frequency at first, you hit a point where the “proximity effect” increases resistance. You can mitigate it with litz coil construction, but only so much.

Then coundn’t you scale the size smaller for higher frequency to shift the Q point? Or maybe this is near-field quirk that’s not so simple to find. Damn Maxwell had to go and make things so complicated.

Maxwell Demon want to get involved here.

I don’t think I’d sit in the car while that was going on, at least for the first couple of years.
This is exciting stuff, having highway speed induction charging in truck lanes up long grades, or even just assist would be quite the range extender.

Should be safe, in theory – since it’s non ionizing radiation. But. . I’ve also read reports about people living next to transformers have a higher cancer rate.
If you could park, push a button to activate charging, with automatic payment AND get 30 seconds to leave the car. . That would be nice for some people.
But should offer instant charging for people who want to add range while waiting for green light and so on.

Yeah, all non-ionizing radiation is safe… Just what everyone wants you to believe. You might want to search engine the alternative viewpoints.

Many scientists do not like 5G health effects, as a for instance of another thing that is perfectly safe, until it isn’t. Rather like ‘Clean Diesels’ from VW. They might exist but VW ain’t gonna be making ’em.

In terms of diesel engines, I wonder why no one has considered ban opposed piston engine for a PHEV. A far better power/weight ratio than conventional engines, less complex, more efficient(50% thermal efficiency is claimed to be possible), and quiter… All good things for a PHEV(or even a pure fossil-burner for that matter).

Don’t forget the “power line parable”. There was a European study that found increased cancer in people living next to power lines. But after it got a lot of press, people started pointing out fundamental problems with the study. Near power lines tends to be places people find undesirable. The power lines are unsightly, and sometimes noisy. Thus people living near them tend to be lower income, and fall into a different group health – wise, such as increased smoking, blue collar jobs, etc.

Sitting in the car is actually safer, as the body frame is a weak “Faraday” shield, and the battery floor is another shield. I doubt any human will be affected. maybe a stray cat looking for warmth under the EV would be affected.

What’s the status of the related safety testing? What happens if the cat sticks her paw between the plates? What happens if an piece of metallic trash blows between the two plates? What happens if the wireless charging spot is outside and dirty? Would be a great message to the mass market.

Mercedes and Audi has made waterproof wireless chargers for outside use. They have also test units that is under the blacktop/cobble stones.
Under the car, there is no electrical connections, so a soda can or metal foil would not be a safety problem.

Very interesting. The efficiency and gap are looking nice.

This technology would require high-power electronics in the car to convert HF-AC into DC. The current high-power chargers (CCS, Chademo) have this electronics in the stations, the cars only require cabling.

So, due to cost reasons, this won’t come on this power level in passenger cars. On Level 2 power (e.g. up to 22 kW) this could be done using the build-in chargers.

Correct!! Everyone is forgetting this step! Those giant AC to DC converters sitting behind a fence at every supercharger are going to fit somewhere on the car? Good luck! This is great for the on board chargers that are already there.

I am also concerned about the efficiency rating measurement. Are they saying 97% from coil to coil? Are they including AC into the wireless transmitter at the board level, across the coils and DC output on the other side? Maybe some combination in between?

Not now, but I am pretty sure at some point privately owned passenger cars might have such powerful chargers. But IMO it’s more interesting for other applications. Police vehicles, fire trucks and other emergency vehicles and especially autonomous vehicles would benefit from it.

It’s rather unpractical to have a robot plug in an autonomous vehicle, since it takes up space. But you can easily fill up a small parking garage with autonomous vehicles and place those inductive chargers under the parking lots. That means no complicated mechanical parts, that take up space, can fail and need maintenance.

And with vehicles that need to work 24/7, it’s rather cumbersome to always keep them plugged in. Sure it’s possible, but in situations where every second counts, not having to unplug a vehicle is a benefit.

I would be more then happy with 22kW, og even less. Just add some charge while shopping, while at the gym, library . .
Low price on a wireless charger is more important then a lot of power. It should be cheap enough to install a lot of units.

Dynamic charging is very exciting. Sections of highway near cities could be retrofitted with high output charging lines under the road. Add to that solar roads (like the one in China). So long as the length of the charging sections are long enough to top off your vehicle until the next one down the road, you’d never need to stop, except for biological reasons (or are you a robot?). Cars wouldn’t necessarily need large batteries then either. Try doing that with an FFV!

And yes the picture says it all The Geeks will Rule the WORLD….WELL DONE GUYS!

I suppose no one suggested that the geeks remove their safety glasses prior to the photo shoot?

Probably because the picture is taken in the lab where the lab rules requires safety glasses at all time.

It should be much easier to make vandalism resistant charging stations with this. Great news.

That s awsome, game changer

I wish on all these technical press releases they wouldn’t be so vague. Are they saying 97% efficient from the ac power input to the battery terminals, or some subset of that? In other words, if the system is providing 120,000 watts DC or PDC at the battery terminals, is the power input to EVERYTHING less than 123,713 watts? How many VA is that? If true then that surely is an advance.

Of course, they could include a spec sheet of what is happening – as was done once with that Canadian Leaf and Volt WIRELESS charger. Only by examining the spec sheet could one find how horrid the thing actually was. Yes it did charge the car at 3.3 kw, but it was ratty to the power supply.

Good point!

I do like that they emphasize on efficiency though, because many, even on this tread with supposedly better advised people, the efficiency factor is buried deep under other factor such as look, color, form, impression, acceleration or vehicle type.
I wish educated people would put efficiency on their top priority, because this is really what about EV or any meaningful sustainable solution.

More precise specification would be appreciated.

I have the same doubts with this vaguely claim. But I think it’s still an improvement and hope there will be more.

“The wireless system transfers 120 kilowatts of power with 97 percent efficiency…”

WOW! That looks like a game changer. No more 10% or more loss for wireless charging, and 120 kW of power is significantly more than I’ve seen demonstrated by others. This should make wireless charging of EVs much more viable!

Not to ignore the concerns about the claim being a bit vague, as noted in comments above. But this claim is from the Oak Ridge National Laboratory, not some unknown startup trying to attract investor money with half-baked, wide-eyed claims. When it comes to having a solid reputation, it’s very hard to beat Oak Ridge!

(⌐■_■) Trollnonymous

This is great and all but……
What’s the total cost of this thing vs. current DCFC stalls/stations?

This would be great for home use at 10-20kW charge rates. Of course cost will definitely be an issue……..again.

nice work!!

Damn, that is VERY impressive. I’m a little skeptical. does this require super good alignment between the car & charger?

what would happen if a rodent goes between the charging plates? 🙂

97% efficiency on the 120kW is a loss of 3.6kW. Powerful enough to charge the Volt.

You won’t get it charged much in some 40 minutes or so, though…

This is HUGE.
I have never been a fan of wireless because of the inherent inefficiencies. This could change a lot of things. In particular, the ability to help accelerate vehicles getting on to the highways, might be pretty cool.

That’s wonderful — and completely theoretical, for the time being at least. Only AC power can be transferred wirelessly, and hence the car’s onboard charger must be used. And that in turn means hardly any car on the market can charge faster than 22 kW (early Zoe models actually can handle 43 kW, but they downsized the charger because very few type 2 sources can deliver more than 22 kW). The majority can’t even go beyond 7.4 kW.

Efficiency goes up with power level for wireless, so it will be less than 97% in the real world. More like 90% probably. That’s still ok — even cables have about 3-5% loss.

Perhaps a 75 kW A/C charger won’t cost too much, but it certainly would have to be retrofitted to the cars.