'Metamaterials enhances wireless power transfers'
http://ecomento.com/2015/04/27/audi-wireless-electric-car-charging-system/ Audi working on wireless EV charging system April 27, 2015 | [image http://cdn.ecomento.com/wp-content/uploads/2015/04/Audi-wireless-electric-car-charging-740x425.jpg video https://www.youtube.com/watch?t=80&v=cdAmM9p58ps Audi CES 2015 Teaser: Those Dogs Audi USA Jan 5, 2015 Audi returns to the Consumer Electronics Show in Las Vegas, Nevada to showcase the latest in innovative vehicle technologies ] Dr. Ulrich Hackenberg, Audi’s technical chief, says the company is working on a wireless charging system that he says is nearly ready for production. The system will be an option on the Audi Q7 e-tron 3.0 TDI Quattro. “It’s not so convenient today to take a cable and plug it in and [unplug it] repeatedly for some people,” Hackenberg says. “”n my own garage, I sometimes have to go around the car with the cable or over the car and around the tools to get to the plug-in point, so I know we have to hurry with inductive charging.” There are technical issues with wireless charging that have to be solved. In most cases, the rate of charge is substantially lower than it is for a charger connected by a cable. Also, the greater the distance between the charging plate mounted to the garage floor and the wireless receiver built into the underside of the car, the lower the charging rate will be. Audi says it is working on a system that will raise the charging plate once the car is in position to reduce the distance to the receiver, which will enable higher charging rates. “Our system will start with 3.6 kW of charging and it will go to 7.2 kW soon, and there are ideas to go higher,” says Hackenberg. Aligning the two components is also critical to getting the best performance. But with the coming of autonomous driving features that will allow cars to park themselves in precisely the correct spot, proper alignment won’t be that much of an issue in the future. Convenience will be an important factor when it comes to members of the public accepting electric and plug in hybrid vehicles. BMW has already noticed that not as many city dwellers are buying its i3 electric sedans as it expected, largely because finding a convenient place to charge them is fraught with difficulties and frustrations. A century ago, a simple innovation changed automobiles from being suitable only for use by rugged individuals to devices that anyone could drive. It was called the electric starter and it changed everything. It is amusing to think of someone like Ulrich Hackenberg tripping over trash barrels as he struggles to connect the latest Audi prototype to the charger in his garage. But if he finds it a hassle, what will ordinary people think? Wireless charging may prove to be the breakthrough that brings electric and plug in cars to the masses. [© ecomento.com] http://phys.org/news/2015-04-wireless-power-metamaterials.html Wireless power transfer enhanced by metamaterials [20150430] by Lisa Zyga feature [images / Q. Wu, et al. ©2015 EPLA http://cdn.phys.org/newman/csz/news/800/2015/wpt.jpg WPT Wireless power transfer between two coils. The metamaterial is the gray 3 x 3 square embedded into the coil on the right http://cdn.phys.org/newman/gfx/news/hires/2015/1-wpt.jpg WPT (a) A large increase in transfer efficiency (purple line) at a distance of 2 cm is measured when both the transmitting and receiving coils (T and R, respectively) are embedded with the metamaterial (yellow). (b) Measured efficiencies at different distances for the case where both coils are embedded with the metamaterial. Although the efficiency drops as transfer distance increases, the efficiency near 20% at 4 cm (blue line) is ideal for some medical devices, such as wireless charging for implanted heart pacemakers ] (Phys.org)—Over the past decade, research on wireless power transfer has led to the development of several commercial applications, such as wireless charging of mobile devices and electric toothbrushes, as well as wireless powering of radio-frequency identification (RFID) tags. However, these applications are restricted by limitations on the distance and efficiency of current wireless power transfer technology. In a new study published in EPL, scientists at Tongji University in Shanghai, China, have experimentally demonstrated a way to improve the efficiency of wireless power transfer by using magnetic metamaterials. The new method improves the efficiency of the design from a few percent to nearly 20% at a distance of 4 cm, which could pave the way toward new applications, including wireless charging of implanted pacemakers and electric vehicles. The concept of wireless power transfer dates back to the 1890s, when Nikola Tesla began experimenting with wireless electricity with limited success. Now more than a century later, the idea has again attracted attention. In 2007, for example, MIT researchers demonstrated wireless power transfer and have been developing products under the start-up "Witricity." Coincidentally, metamaterials have had a somewhat similar history. Around the turn of the 20th century, scientists began exploring the idea of artificial materials that could manipulate light in unusual ways, but not until the early 2000s were true metamaterials first fabricated. In the new paper, the Tongji researchers have embedded magnetic metamaterials into the coils used in non-radiative wireless power transfer, which is the method used by most of today's wireless power transfer applications. In the researchers' design, one coil creates a magnetic field, which is captured by the second coil as voltage. Like all metamaterials, the ones used here contain subwavelength microstructures that can manipulate electromagnetic waves in ways not possible with other materials. Here, the metamaterials are assembled with "meta-atoms," which are 2.6-cm etchings on the spiral copper coils. This particular size of 2.6 cm is important because it allows for strong coupling between the deep subwavelength resonant modes of the meta-atoms, and this coupling is responsible for increasing the transfer efficiency. "By embedding metamaterials into non-resonant coils, the overall efficiency of the wireless power transfer system is found to be greatly enhanced, due to the coupling between metamaterials," the researchers wrote in their paper. Although the efficiency decays quickly as distance increases—from 32% at 3 cm to 15% at 5 cm—the 20% efficiency near 4 cm marks a sweet spot for certain applications, such as wireless charging of pacemakers and other medical devices. In the future, the researchers hope to build on this metamaterial-enhanced wireless power transfer method to develop many other applications. The scientists expect that, due to the metamaterials' homogenous magnetic behavior, the metamaterials can be assembled like ordinary materials, and so can avoid the technical fabrication challenges that many metamaterials face. "Since the wireless power transfer system based on metamaterials has many benefits, we believe it can be widely used in medical research, electric vehicle charging, the civilian industry, and so on," the researchers wrote. Explore further: Researchers develop new wireless power transfer technique http://phys.org/news/2014-08-wireless-power-technique.html#inlRlv More information: Q. Wu, et al. "Wireless power transfer based on magnetic metamaterials consisting of assembled ultrasubwavelength meta-atoms." EPL. DOI: 10.1209/0295-5075/109/68005 http://phys.org/journals/europhysics-letters/ Journal reference: Europhysics Letters (EPL) search and more info website [© 2015 Phys.org] For EVLN posts use: http://evdl.org/evln/ {brucedp.150m.com} -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/EVLN-Audi-wireless-EV-charging-system-tp4675406.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
