Electric Cars as Fast as Ferraris 739
Ubergrunt writes "A Welsh engineering company has made a motor to be used on electric cars that will make them as fast as a Ferrari. "The motor is revolutionary in that it contains no bulky permanent magnets. Instead it relies on transmitting electric pulses across up to seven rotors, arranged in different phases. These are "fired up" in turn, much like the pistons of an internal combustion engine. There are no gears - the motor provides enough torque at one revolution per minute to put a vehicle into motion - and it spins at up to 2,500rpm.
"Size for size, we can provide 400% more torque than any type of motor currently available," says managing director John Bryant."
Re:Torque (Score:3, Informative)
To be able to start the car at all it has to have good torque at zero RPM
Gas turbines have this beat (Score:5, Informative)
Of course, you need a supply of liquid hydrogen and oxygen to run the beastie, but if your really need the power, this is the way to get it.
If LH2 and LOX are too exotic, then try a helicopter gas-turbine. A 600 pound gas turbine can easily provide 5,000 hp.
The counter-argument is that a gas turbine needs a serious transmission, which adds to the weight of the unit. The counter-counter-argument is that these electric motors need batteries or a motor-gen set which also adds (arguably more) weight to the vehicle.
Re:the oil and car industry will band together (Score:2, Informative)
Re:Batteries batteries (Score:3, Informative)
A "Dual-fired" generation plant is one that can run on either natural gas or oil. It gives the operator the option of using what is cheaper at the time.
FYI: Permanent Magnet Motors (Score:3, Informative)
More recently (still at least a decade) AC motors have been growing in popularity, and they work on the principle of magnetic induction. Of course, it's difficult to start one if the rotor is completely demagnitized as it prefers that there's at least a tiny bit of a field, but nontheless...
Jw
Re:the oil and car industry will band together (Score:5, Informative)
Did you RTFA? These motors are designed to be hooked directly up to the wheel. That means that this engine doesn't NEED any transmission because it generates enough torque at 0 RPM to move the vehicle, and can rotate fast enough to propel the vehicle at all speeds.
And electric motors, properly built, are very very tough.
How is this new? (Score:3, Informative)
Skipping over all the issues over energy storage that are leading to the success of the hybrid design....
How is this motor new? They don't describe how multiple rotors are connected. They don't even mention the basic motor technology.
Not having permanent magnets is not a selling point in Real Motors. Permanent magnet motors are only used in very small, low-power applications--tape player, model car, windshield washer pump, hard disk motor.
Replacing the permanent magnet with an electromagnet lets you build a MUCH bigger motor. And how you connect it (the field or stator coil) to the rotor coil lets you do neat tricks. It's the motor that made electric rail possible. Same thing is in those old "Mixmaster" mixers, rigged in such a way that they keep constant speed under almost any load. Same sort of motor in your vacuum, blender, power drill, and so on. They're called "DC Machines", but because of the electromagnet, they can run off AC as well (0-60 Hz, it says in the old Mixmaster manual), and are also called "Universal machines".
But with modern solid-state controls we can do better using various kinds of "AC machines", neither of which use permanent magnets either. An induction machine is your basic steady-speed AC workhorse motor--tablesaw, drill press, washing machine, drier, window fan, fridge or AC compressor, furnace fan. They're weak at start, so tend to come up to speed slowly. An induction machine is basically a lump of aluminum in a changing magnetic field. Set it up with 3-phase AC and you don't need anything at all, set up 3 coils and put a coffee can in the middle and watch it turn. Change the frequency of the AC and you change the speed. For better power, replace the lump of aluminum with actual wound coils shorted together--no brushes, no commutator, no permanent magnet.
Next is the "synchronous machine", which can be built with a permanent magnet, but you generally don't. You do need sliprings or brushes with this one, as you provide power to a rotating electromagnet. Your car's alternator (and some bikes) use one of these--by adjusting the current through the rotating electromagnet, you adjust the generated voltage. (That's how your charging system regulator works--by changing the amount of power actually generated.)
You get bags of torque from a synchronous motor, but the problem is getting one to start turning. The classic way is to start it as an induction motor, then engage the rotating electromagnet when it is at speed. If you just start bashing 60 Hz AC into one already in synchronous mode, it will just vibrate, as the magnetic field (still thinking 3-phase) are zipping by faster than it can turn to catch up.
But with recent (last 10-15 years) improvements in power switching semiconductors, we no longer have to settle with 60 Hz AC. And, on DC supplied vehicles, we have to invert to power a synchronous machine anyway. So, you build a frequency-controlled inverter, so you can start the motor from near-zero Hz and bring it up to whatever speed you want--the synchronous nature of the beast will "lock" it to the speed from the inverter. (And you can watch the power on your drive circuits to see if you are trying to drive it too hard and are about to lose synchronization.) You can do that trick with an induction machine too, but an induction machine relies on the stator windings to induce a magnet in the rotor, so it's not so good at very low frequencies. On the other hand, it starts easily, so you don't need to match frequency to motor speed, it will just "slip". (The difference between syncrhonous speed and actual speed is called slip.)
One final trick: I've been assuming you've got a 2-pole motor: One north, one south around the outer circle at any given time. At 60 Hz, this gives you 3600 RPM--each time the voltage makes a complete cycle, the rotor has to turn to follow. Another poster [slashdot.org] hit on the right basic idea for electr
Re:the oil and car industry will band together (Score:3, Informative)
Electric motors, especially the new(ish) brushless motors are nearly maintance free. Having only two critical failure points being the front and rear bearings there is almost no reason for these things to break down. Kept clean I wouldn't be supprised to see a million miles on the motors. I'd say even to the point that you may be able to buy new cars without motors and swap in your old ones.
Re:the oil and car industry will band together (Score:3, Informative)
No transmission is necessary. And it's a process that has been well tested. Trains are diesel electric. They have motors mounted in the wheel assemblies. Then they have one large diesel engine running a generator providing the power to the drives. And another that runs a separate generator that provides power to the train. And a bit of trivia... the unit that powers the drives is a 2 cycle engine while the other is a 4 cycle.
The reason they use a diesel electric is the amount of torque required would require a huge transmission. Gas/Diesel engines need transmission because they have a sweet spot where they provide the most torque. Electric motors, on the other hand, are capable of providing pretty much the same torque at 1 rpm as they are at their max rpm.
Personally, I'm with another poster here. Diesel electric should be investigated for heavy duty applications like Semis and Buses.
But even with the current hybrid (gas) electric cars there is a healthy gain in efficiency.
Re:the oil and car industry will band together (Score:2, Informative)
IC engines use an explosive propulsion. An electric engine does not. Which is safer?
When your single IC engine dies on the freeway, you will to (or at least you are not going anywhere). If one of your 4 an electric motors die on the freeway, you loose some (25%) power but can drive home anyway. If you are worried about the car pulling to one side, I'm sure that the controller that is undoubtedly making several thousand adjustment per second will adjust the power to the other motors to compensate.
If one of the bearings on your wheels hubs of your IC engine powered car freezes up, you might flip. If one of the bearings on the electric motor sieze up, you might flip... Ok, that one is equal, but how often does this happen anyway?
Your average IC engine has hundreds of moving parts with thousands of things that can go wrong with them. Then we get to the transmission, the differential, the fuel system, the smog systems, the electrical systems, etc... Your average electric motor has as few as 1 moving part and a limited number of failure points (a blown fuse would be the main one).
Your IC engine gets so hot and has so much friction that it requires several fresh quarts of oil per year. Your average electric motor will probably need to be regreased once or twice in it's life because it is several times more efficient (read cool and less friction).
As for accurate voltage... Where do you get this idea? Try hooking up a variable pot to an electric motor some time and see what happens as you turn up and down the resistance (and thus the voltage to the motor). All that happens is that the motor speeds up and slows down. There are many very well tested and proven methods of using resistance or speed feedback from an electric motor to very precisely control it's RPM and torque. These are not "far in the future" concepts but rather "far in the past" inventions. Nothing new or particularly difficult here. I would be VERY suprised if electric motors are not orders of magnitude more reliable and safe than Internal Combustion engines.
Re:Obligatory bash quote (Score:3, Informative)
torque != power. Power = acceleration.
AIK
Re:Obligatory bash quote (Score:3, Informative)
Not equal, MAXIMUM. And yes, because it does delever maximum torque at low RPM, it does mean it is delevering the type of energy needed to start quickly. Horsepower means how fast you can go. Torque is how fast you can get there.
For just getting from 0 to 60 as the grandparent was talking about, low RPM torque is the way to go. You don't need torque at higher RPMs unless you are pushing for higher speeds.
Here's a little primer [vettenet.org] for you: