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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
I love Jesus, except for his foreign policy.
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
I knew if I waited long enough I would get my wind-up toys back. But why aren't they using a big spring?
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%.
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.
Unbelievably ignorant comment. The 12.5 kW is running through the free space between the cat's electrons and nuclei with only a tiny tiny fraction of it impacts anything in the cat, none of it having any physiological effect. It's been long established that magnetic fields are basically inert to biological matter. In 1997 they levitated a frog using 16 Tesla field, which is orders of magnitude stronger than anything used here, and the frog had no subsequent physiological problems: http://www.newscientist.com/article/mg15420771.600-frog-defies-gravity.html The rate of change of the magnetic field is far too slow with this mechanical rotation to create an appreciable electric field--there's no measurable charge separation that can be induced in the cat. There's also no EM waves anywhere in the vicinity due to an extremely long wavelength, putting the whole system including the car, cat, and rotating magnets in a near field situation.
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Different type of charging system.
The charging system in your references is working via induction - basically a transformer and the energy is transferred through an alternating magnetic field that creates a current in the coil on the car.
The system that's references here appears to use a magnet to spin a magnet on the other side that then spins a generator. I'm not sure exactly how the intensity of the magnetic field would be different because the power is still being transmitted magnetically, but it's going to be at a much lower frequency. The induction charging has a frequency of 40KHz while this would be more like 60Hz.