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Canadian Researchers Create Wireless Charger For Electric Cars
An anonymous reader writes "University of British Columbia researchers have developed a wireless charging system for electric cars. It involves a spinning magnet beneath the parked vehicle which turns another magnet in the underside of the car. Charging takes four hours and is about 90% as efficient as plugging in. From the article: '"One of the major challenges of electric vehicles is the need to connect cords and sockets in often cramped conditions and in bad weather," says David Woodson, managing director of UBC Building Operations.
"Since we began testing the system, the feedback from drivers has been overwhelmingly positive."
Four wireless charging stations have been installed at UBC's building operations parking lot. Tests show the system is more than 90 per cent efficient compared to a cable charge. A full charge takes four hours and enables the vehicle to run throughout an eight-hour shift.'"
OK, so it can double as a garage heater in winter. However, in the snowier parts of the country (i.e. NOT Vancouver and its suburbs), this will not be appreciated for outdoor use - lots of meltwater turning into smooth ice...
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
Nevermind...finally read the article thoroughly. They're just placating the idiots who think that other types of wireless power transmission is black magic or something, as if quickly rotating magnetic fields (not to mention large magnetic discs) is any safer than electrical fields alone. Apparently these people have never heard of electromagnetism and aren't aware that the two are intrinsically linked.
Not if I'm paying for the electricity. I don't really feel like paying 10% extra to charge my car for the convenience of not having to plug it in. How much more does this charging system cost and how much does it add to my car's weight? Qualitatively, let's estimate that as "too much."
I have visions of the recharge lane.
Not that I'm complaining... I'm just a bit surprised. News for nerds north of the 49th.... If this was November, I'd suspect some sort of alliteration joke to be forthcoming.
File under 'M' for 'Manic ranting'
This is used all of the time in pumps where you don't want a dynamic seal. You have permanent magnets spun by a motor and inside a sealed case the pump is coupled by a magnetic field.
http://www.proconpumps.com/brands/Magnetically-Coupled-Pump-(Sealless).html
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Straw man. It's no harder to close the magnetic circuit of an inductive charging system (electromagnets) than it is a pair of permanent magnets like this, if you know what you're doing. The only difference is this system will produce a much lower frequency electromagnetic oscillation--in fact, it would be easier for the inductive system, since higher frequencies require smaller and less sophisticated materials to contain. What is the radiative effect when the two spinning magnets are not centered perfectly, as compared to a non-centered inductive system?
Also, permanent magnets are expensive, and annoying. Try not to drop your credit card on the garage floor, even when it's turned off--and what is going to stick to the bottom of your car as you drive?
The only remaining question is: if there really is a power efficiency gain, is it not wholly negated by the added weight of this ridiculous, possibly unreliable mechanical contraption, compared to a standard induction charger?
Why not make it a two-part transformer? You'd just have a spinning magnetic field with no moving parts. You would also eliminate two extra rotary electrical machines (the motor in the charger and the generator in the car).
Ezekiel 23:20
Thank you, Nikola Tesla.
The mind conceives, the body achieves, the spirit manifests.
I knew if I waited long enough I would get my wind-up toys back. But why aren't they using a big spring?
Fortunately charging a car wouldn't need a 100kW microwave. Both because you don't need 100kW (unless you are in a hurry of charging your car, but then, I'm not sure the battery would take that anyway), and because you'd not use microwaves to do it (after all, you don't have to remote-charge your car; instead you'd put it directly onto the charger).
The Tao of math: The numbers you can count are not the real numbers.
Nope, us Canadians have nothing better to do on a Saturday other than post articles to Slashdot. Y'know, we have bitter cold and snowy winters, eh?
Brilliant. I'd make a teensy change. Replace the spinning magnet outside the car with a cable, and replace the spinning magnet and generator in the car's underbody with a plug. Run power through the cable to the plug, but only after there's been a handshake between the cable and the plug. Use the equipment that would spin the magnets to establish a physical connection between the cable and the plug.
I think the efficiency of this, compared to old techniques, will be closer to 100% of existing efficiency than to 90%.
because you can park on top of 4"-8" of snow just fine even if the lot isn't plowed.
All of the above was encrypted with a Quad ROT-13 method. Unauthorized decryption is in violation of the DMCA.
It's called a "magnetic circuit" (scroll down halfway for an actual diagram). They are used all the time in high-efficiency motors and solenoids. By putting the right type of iron in the right shape around a coil or a permanent magnet, the iron provides a "path of least resistance" for the magnetic field lines and the field that escapes from the iron is small or miniscule.
If you have ever taken apart a mechanical hard drive, you will have found the very strong neodymium magnets used in the head travel motor are attached to a piece of metal--probably an alloy called "mu metal" or similar--and the observable effect is that you can only magnetically stick things to the magnet side, not the mu-metal side. That is because of where the magnetic field lines go: instead of going out one side of the magnet, around in the air, and back in the other side, they go out into the air on ones side and then directly into the mu metal, then through the mu metal and into the magnet. This not only shields the magnetic data on the hard drive platters from the motor magnets, but also greatly increases the efficiency of the motor.
I assume they will do the same thing with this car. There will be a pretty significant "air gap" in the magnetic circuit, which increases leakage, but it is easy to provide iron on the top side of the in-car magnet so that all the field lines are directed downward and away from the interior of the car.
Street. Shark.
IRRC the biggest unknown with these chargers is that it's effects on a small animal that chooses to sit right in the path of the inductance loop is largely unknown.
It's a bigger issue than you would think, since it does put out some heat, it is extremely likely that your family cat will find a new favorite sleeping place under the car.
Granted the biggest risk might be that of a 'squashing' incident when you park or drive off without first checking for your loved one; but the effects on living tissue of spending hours sitting on top of a giant electromagnet are not exactly known.
We know that running a 60 watt TV from across the room via inductance has zero effect on human health - but running 12.5kW through a cat is a slightly different equation.
You're an idiot. Due to the slow rotation, the slow rate of change of the magnetic field puts the whole system is in a purely magnetic near field regime. While the rotating magnet emitter would, all by itself, produce extremely long wavelength EM radiation starting at a few kilometers distance (any closer, the only electric field that can be induced is in conductors), that does not happen when there is an interacting object in the near field which acts as a sink for most of that energy. Given their efficiency numbers, the leakage is 10%; a kW or even a few of multi-km long wavelength fields are not an issue for biological matter, even less when they don't even exist as EM until km distance over which you've had quadratic falloff! Anywhere within the vicinity of the rotating emitter / car receiver system there is only a relatively slow varying magnetic field and no measurable charge separation can be induced by this in biological matter. Magnetic fields of 16 Tesla were used to levitate a frog around 15 years ago, and the frog had no physiological effects during or after the experiment--and those are magnetic fields orders of magnitude higher than what was ued here!
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