See all those Audi A1 e-trons in the photo above? In the near future, they could look exactly the same – i.e., without any visible cords – but be charging their batteries, thanks to Audi's work on wireless charging.

Today, Audi released information on seven areas of the "automotive technology of tomorrow" it is working on. Autoblog has a primer on all seven, but we thought it made sense to dig into the cord-free charging aspect. Sadly, Audi isn't describing its work in any great detail.

Here's what we do know: the inductive charging system could one day be standard on "plug-in" Audi vehicles and would include technology from the Boston-area-based WiTricity Corporation. Officially called "Audi wireless charging" (no points for creativity, there), electricity is sent from a coil in the concrete to one in the car thanks to an alternating magnetic field that is only activated by the vehicle driving into position. Thus, Audi says, "there is no risk to human beings or animals." Project leader Dr. Björn Elias said in a statement that there is a lot of potential for this technology:

Imagine you drive to work in your Audi e-tron, and on the way home you stop off at the store. Wherever you park the car, its battery will be recharged – perhaps even at traffic signals. These short recharging cycles are ideal for the battery: the smaller the difference between the values before and after recharging, the longer the battery's potential operating life.

A very cool idea, but also one that's far away. Nonetheless, other automakers – like Mitsibishi, Daimler and Nissan – are also working on contact-free ways to fill up your car's battery pack. This is why the deputy director at the power electronics and electrical power systems research center at the Oak Ridge National Laboratory said last May that wireless charging will one day be the standard way we juice up our cars.
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Audi wireless charging

Ingolstadt, 2012-02-29

Audi is working flat out on the future of 'electromobility' – on its e-tron models and their technology. The brand with the four-ring badge pursues a comprehensive concept that includes every aspect of the task, including recharging the traction battery. In this area, automatic and contactless charging is an especially interesting prospect: Audi's name for this is Audi wireless charging.

Project Leader Dr. Björn Elias says: "We aim to offer our customers a premium-standard recharging method – easy to use and fully automatic, with no mechanical contacts. It uses the induction principle, which is already well known from various products, from the electric toothbrush through the induction cooker hotplate. We are now using it to recharge cars."

Dr. Elias is in charge of the Audi wireless charging pre-development project at Audi Electronics Venture GmbH (AEV), an AUDI AG subsidiary. Within the scope of pre-development in the area of Audi electronics, AEV has the task of identifying new trends in the vehicle electronics environment, checking their suitability and bringing them up to series-production readiness, if necessary in cooperation with outside companies.

An important partner in the area of wireless charging is the WiTricity Corporation from Watertown, near Boston. The American company supplies technical components which are integrated into the vehicle's complete system, in particular the coil systems that are integrated into the plates. The primary coil is normally located at the roadside or on a parking lot; the secondary coil is on the underside of the Audi e-tron vehicle.

When the Audi e-tron or some other suitably equipped electric vehicle is driven to a point above the primary coil in the road surface, the battery charging process starts automatically. Alternating current in the primary coil generates an alternating magnetic field that crosses the air gap and induces an alternating voltage in the secondary coil on the car. This voltage is rectified and fed to the car's traction battery. The process is terminated when the battery is fully charged or if the recharging process is interrupted by driving the car away or switching it off manually.

The primary coil – for instance in the car owner's garage – can be flat on the floor or even under the surface. It is unaffected by rain, ice or snow, and since the alternating magnetic field is only built up when a vehicle is above it, there is no risk to human beings or animals.

This charging technology can be integrated into the traffic infrastructure wherever needed, for instance as garage parking equipment or on housing estates. Dr. Elias outlines a medium-term scenario: "Imagine you drive to work in your Audi e-tron, and on the way home you stop off at the store. Wherever you park the car, its battery will be recharged – perhaps even at traffic signals. These short recharging cycles are ideal for the battery: the smaller the difference between the values before and after recharging, the longer the battery's potential operating life."

Much more work will be necessary before countrywide recharging infrastructures can be built up. Audi is playing an active part as a member of the expert workgroups in Germany and America that are aiming for a uniform public standard. Dr. Elias expects automatic wireless charging technology to go into series production in a few years' time. With it, electromobility has the potential to take a further big step forward.


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  • 26 Comments
      • 2 Years Ago
      The first video of Audis OLED lighting concept at www.oled-display.net
      brotherkenny4
      • 2 Years Ago
      The charger/wireless charging issue really defocuses things away from the real issue and that is that no car company has truely mass produced an electric car. 10K is not enough to get the price down, and so no one is serious yet. When people say that we need more charging infrastruture ahead of vehicle adoption, it adds an extra unnecessary burden to the initial introduction. The car companies should look to get a million plug in cars out in the hands of the public. Then there will be a business case for people adding charging units. Until then you are just giving people the impression that infrastructure must exist for the technology to be viable, and that is a lie. Home chargers will be the primary means of charging the initial plug-in vehicles, and it makes much greater economic sense. I think people are beginning to see that the range anxiety thing was a bit of an intentional creation to actually discourage consumers now. I think this (the lack of charging infrastructure) may actually be the same. Someone who isn't rational (which is most people who think of themselves as "consumers") will think that without the charging infrastructure everywhere, an electric vehicle is not a viable option, which is just not true in our multicar multidriver families.
      nbsr
      • 2 Years Ago
      Lack of accuracy is just a symptom of a larger problem - I'm afraid the whole thing is a BS. Go to http://ieeexplore.ieee.org/ and type "resonant power transfer". Very few people seriously consider applying these techniques to EV changing and those who do (http://dx.doi.org/10.1109/VPPC.2009.5289747) restrict themselves to power outputs of 100W or so. For a good reason - no one wants to be perceived as an irresponsible scientist throwing unsupported claims. That doesn't mean it won't work at all, just the performance may not exactly meet all of your expectations. Here are characteristics I find likely: power transfer of 3kW at
        DaveMart
        • 2 Years Ago
        @nbsr
        If you can't be put together a proper critique, I can't be bothered to search around and try to work out what you are on about. The likes of Oak Ridge, Nissan and BMW all seem to think that the idea is perfectly workable, and are looking getting the costs down rather than basic technology now.
          nbsr
          • 2 Years Ago
          @DaveMart
          Letstakeawalk: Well, "doubt" isn't a good word. I'm *sure* it won't work as advertised - I'm just trying not to offend all the technology passionates here. It isn't exactly a scam of EEstor magnitude but it is still a useless and dangerous gadget. The last thing I expect from it is to actually help adoption of EVs. Ultimately you can do with your cash whatever you like. If you like these chargers go ahead and buy one (once they become available). I have nothing against it as long as you don't try using it near my house.
          DaveMart
          • 2 Years Ago
          @DaveMart
          nsbr: These 'useless and dangerous gadgets' have been running buses in Italy quite happily for many years: http://www.greenchallenge.info/MediaDetails/ACuriousTripToItalyInductionchargedBusesInTorino.htm No sign yet of heaps of dead Italians, or the power grid failing because of the huge power draw occassioned by the massive inefficiencies you imagine.
          Letstakeawalk
          • 2 Years Ago
          @DaveMart
          You can doubt all you want, nbsr. http://green.autoblog.com/2011/05/05/analyst-wireless-charging-of-plug-in-vehicles-to-become-standar/ Wireless charging is the next step towards making BEVs and PHEVs acceptable in the larger mass-market.
          nbsr
          • 2 Years Ago
          @DaveMart
          I can't really get more "proper" without doing the thing myself. And I won't do that because in my opinion that's a waste of time. The only thing I can do is to ask you _again_ to check the papers people involved in this field wrote. There aren't that many of them, btw. If the companies you mentioned are only "looking getting the costs down" then where are all these fantastic (albeit expensive) wireless chargers? Let me know if you get hold of one, I'd really like to measure it. Companies do strange things to get money. You can easily pay $10k for a DVD cable (sold by a legitimate company, no less). If there are people who want to spend their money, there will also be a company ready to take them. Yes, I'm surprised that Nissan and BMW have joined this trend but in a way, I understand them. It's easier to come up with an expensive gadget that sells than incrementally improve solutions to hard problems.
          nbsr
          • 2 Years Ago
          @DaveMart
          Letstakeawalk: Thank you for the link. Always good to see some numbers. Sadly, "90-94% eff. at 25cm air gap, more than 4kW demonstrated, 7kW targeted" is pretty much all it contains. If you read the sentence carefully, this is what it really says (I'm not making it up - this is a direct translation): "90-94% eff. at 25cm air gap and unspecified output power", "More than 4kW demonstrated at unspecified distance, alignment and efficiency. The design target of 7kW has not been met.". What it doesn't say is: What was the test environment (clean-room setup? a paddle? any metal objects in vicinity (like a *car*)?). What is the effect on environment (where do the losses go? hopefully they'll heat up the charger, not the owner or his neighbors. Mind you we're talking about losses in order of a kilowatt(s) - that's not a toothbrush charger). What about EM radiation. Who did they demonstrate the system to? Was it a general public, other scientists, a CEO, investors? What was their response? How did they demonstrate it, just switched it on and shown that the car is being charged or have actually measured something? If so where are the results? BTW, I just noticed that my previous comment was cut early. This is what I wanted to write: "Here are characteristics I find likely: power transfer of 3kW at 60% efficiency and distance or misalignment of a quarter of coil diameters, sensitive to environmental conditions and not meeting existing safety and EM interference regulations." These are all ballpark figures but they are based on my own experience in a related field. I would *like* to be proven wrong (that would mean someone has solved real problems) but I haven't seen a single source that would re something substantially different. Instead I see a lot of smoke and mirrors.
          Letstakeawalk
          • 2 Years Ago
          @DaveMart
          Here's a presentation from Oak Ridge: http://www.ornl.gov/adm/partnerships/events/Dec_Spark/Paulus_Wireless%20Power%20Transmission%20Presentation%20-%20Paulus%20v2.pdf "90-94% eff. at 25cm air gap, more than 4kW demonstrated, 7kW targeted" Count me in with Davemart - nbsr's opinion that wireless charging is "BS" is unfounded and unsupportable.
          nbsr
          • 2 Years Ago
          @DaveMart
          DaveMart: That's a near-range inductive power transfer system, very different from resonant systems others are pushing. In my opinion this is the only reliable way of implementing a non-contact charging system but it only works with a narrow air gaps and requires precise alignment of coils. This may be acceptable and valuable for buses (large coils, trained drivers, adjustable floor height, opportunity of recharging at bus stops) but is troublesome and pointless at home where you can simply use a plug instead. FYI, what resonant systems really do is boost magnetic field strength to the point that 1-10% of coupling between coils is sufficient for transferring the required power. So you end up in a situation where most of the magnetic flux is leaking and at the same time the produced field has to be much stronger in order to compensate for it. The result (efficiency, safety) entirely depends on what else (or who) the field couples to. BTW, I've never said anything about power grid failures - that part will be OK, people are wasting tremendous amounts of electricity anyway.
          DaveMart
          • 2 Years Ago
          @DaveMart
          nbsr: The wireless chargers are here for a trial program if you own a Leaf or a Volt: http://www.pluglesspower.com/reserve/
      DaveMart
      • 2 Years Ago
      'A very cool idea, but also one that's far away. ' Not necessarily. That is what I thought, until I found out that it may be possible to do without ripping up the whole highway, and at the low cost of $1 million/mile per lane. 'In the Oak Ridge model, 200 coils would be embedded in a section of the roadway and controlled by a single roadside device; successive coils would be energized as electric vehicles pass over them, providing enough power for the vehicle to reach the next series of coils a mile down the road. John Miller, a research scientist at Oak Ridge, estimates that each series of coils plus the controller would cost less than a million dollars. "Wireless chargers for electric vehicles are so convenient. You don't have to mess with plug cables. You don't care what the weather is. You don't even have to think about it. I think it's going to catch on superfast," Miller says.' http://www.technologyreview.com/computing/39657/page2/
      PR
      • 2 Years Ago
      If you turn your computer screen upside down, the Audi's are making a smiley face at you. This thread is worthless without any efficiency numbers.
        DaveMart
        • 2 Years Ago
        @PR
        There are plenty of efficiency numbers about. They tend to run at around 2-3% across the air gap, and 10% wall to battery for the home charger versions. Some significant portion of that 10% appears to be duplicated by wired installations, so we are talking about a net cost of more than 2% and less than 10%.
          JakeY
          • 2 Years Ago
          @DaveMart
          The 3% air gap efficiency is only achieved by having near perfect alignment, which is done by "parking guidance" in the last 5-10 feet of reaching the station. I'm not sure how much quicker that is compared to just parking normally and plugging in. http://www.pluglesspower.com/images/Plugin_2011_brochure.pdf If you allow larger tolerances, the air gap losses can increase by as much as 10% (absolute, meaning something like 87% air gap efficiency vs 97%). http://www.nissan-global.com/COMMON/PDF/TECHNOLOGIES/te_111013-01-06-e.pdf
          JakeY
          • 2 Years Ago
          @DaveMart
          @DaveMart "That is why induction charging in the home for small devices is also popular." The only popular example I can think of are electric toothbrushes and there are a couple circumstances that made them ideal for induction charging (the exposure to water makes traditional plugs/contacts dangerous; brushes are typically put in holders so there is no issue with alignment or gaps). However, induction charging is rare for other applications (it's being tried out in cellphones but haven't caught on in any big way).
          PR
          • 2 Years Ago
          @DaveMart
          Right, but where between 2% and 10% does THIS charger work at, or does it fall outside these expectations and is therefore inferior to other chargers of the same type? Previous chargers covered here on ABG listed their efficiency. There is no way to compare this charger to previously reported chargers is impossible without any efficiency numbers. Like I said, this thread is worthless without any efficiency numbers.
          DaveMart
          • 2 Years Ago
          @DaveMart
          Here is what WiTricity say: 'Q: How efficient is WiTricity technology? A: The power transfer efficiency of a WiTricity solution depends on the relative sizes of the power source and capture devices, and on the distance between the devices. Maximum efficiency is achieved when the devices are relatively close to one another, and can exceed 95%. Q: Does the efficiency depend on the coil shape or material? A: Efficiency is primarily determined by the distance between the power source and capture device, however, the shape may impact the efficiency. WiTricity uses validated models to predict the effects of distance, shape, and materials on the performance of a given system configuration.' http://www.witricity.com/pages/faq.html From Jake's link Nissan seem to think that they can manage a gap as great as 150mm and a misalignment tolerance of 100mm - it did not want to cut and paste, so I won't duplicate it here. However they are quoting efficiencies as low as 80%. Their induction charging would normally be less tolerant of gaps than magnetic resonance. It does seem fair comment that at this time getting real specific is difficult, perhaps not unusual in a fast developing field on the cusp of commercialisation. I seem to remember reading that Nissan recently upped their efficiency to 90%, although the parameters were unclear. Its worth remembering though that although the efficiency is of great interest to us and our fellow geeks, out in the wild many are not going to be bothered whether they pay $2,50 to fill up their car or $3, but will prefer to not have to plug in their car. That is why induction charging in the home for small devices is also popular.
      • 9 Months Ago
      As a driver I did not enjoy the audi but maybe woth the new technology I hope they can also improove the comfor of the car, as I found it extremely uncomfortable inaide. Tight and clostrophobic. We shall see.
      nbsr
      • 2 Years Ago
      This is all wishful thinking. Safety, power, distance, robustness and efficiency figures look interesting until you realize they are all mutually exclusive. Marketing claims are big, yet data are either hidden or cherry-picked to fit some of them. This contrasts with scientific papers which are toned down (to say the least) and even they make assumptions all over the place (e.g. inductive coupling is safe because in this application we use it for a medical procedure and alternative is to cut the patient open). Lack of rigor is a very bad engineering practice, especially in inductive coupling, which has tradeoffs and physical limits all over the place. Besides, everybody is pushing the idea as if it was going to make a difference for adoption of EVs. It will not - it is worse than a regular wired connection in every respect. Even less convenient if you think about actually using it (instead of handling a plug you now have to play tricks with your car - try to park within 2" from a spot every single time) and it adds cost to already rather expensive BEVs. If anything, it is the reduction of cost that would help the BEV market.
        DaveMart
        • 2 Years Ago
        @nbsr
        Your criticism is about the lack of precision in the field. Since you do not even cite which papers you are referring to the lack of precision seems to be in your critique rather than elsewhere. Perhaps you could provide your source data for your claim that parking has to be with an accuracy of 2", and inform us as to whether this is for inductive charging or magnetic resonant charging. Here is a video of that operation which you make sound at least as complicated as docking a lunar module: http://www.pluglesspower.com/go-plugless/ It also beeps at you when you are correctly aligned. I think I could manage that, somehow. There are buses which have run on inductive charging in Italy for several years. There have been no signs of the heaps of dead bodies or massive drains on the grid that you seem to imagine may result. For lower power devices lots of things already run in the home this way. We are not then talking about totally new technology, but improving something we already know works. Here is the WiTricity site and their magnetic resonant charging technology, including references to their scientific papers: http://www.witricity.com/pages/benefits.html
      noevfud
      • 2 Years Ago
      Inefficient and no big deal. This will be an option on the next LEAf and they are already setting up to offer it on existing LEAFs. Guess what? The LEAF is in production and unlike Audi they are not EV flip floppers. Possible wireless charging on a car that is not available, go Audi! Give me a high five and and Coors Light with a backward baseball cap and cal it GREEN like this blog. :)
        nbsr
        • 2 Years Ago
        @noevfud
        Inefficiency is not a big deal when you think about the cost (energy is cheap). It is "less green" than a charger with a plug but we could probably call it "green enough". The problem with inefficiency is that it results in losses - energy that instead of going into the battery ended up somewhere else. At this power levels even moderate RF losses are problematic.
        DaveMart
        • 2 Years Ago
        @noevfud
        Nissan are no floppers. So it is interesting to note that they are also full steam ahead with inductive charging: 'Nissan is now working on inductive charging, with the first production application of the technology arriving when Nissan’s luxury arm, Infiniti, launches its new EV model in 2014. Nissan says the charging system is 80-90 percent efficient depending on how well aligned the car is to the charging area. That’s about the same range, the automaker says, as a conventional (conductive) plug-in charger because of electrical losses between the plug on the car and the plug in the wall. Inductive charging would certainly leave homeowner’s garages free of cords. But the real benefit would come in the city. "Streetside parking with cords dangling from EVs would eventually go away," says Mark Perry, director of product planning and advanced technology for Nissan. And though Perry hinted that since the wireless system will initially cost about 20 percent more than a conventional plug-in cord charger, he outlined a future scenario in which EVs could eventually get their charge on the go.' http://www.popularmechanics.com/cars/alternative-fuel/electric/2014-infiniti-ev-to-debut-wireless-inductive-charging-system?click=pm_latest
      JakeY
      • 2 Years Ago
      I think the bigger issue is to ensure all these wireless charging systems are standardized. Unlike wired charging, there is no such thing as an "adapter" for wireless charging.
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