How do Tesla motors differ from basic electric motors - what makes them so special?
The unique part is the way the inverter is housed next to the motor in the Model S and X.
The traditional problem with motors in cars is that prior to the Prius, large electric motors were all hand built. An order of 25 was considered a very large order. No one had ever made thousands of large motors on a production line prior to that so it is not possible to go to an electric motor manufacturer and order 2,000.
Every manufacturer of cars with large motors (Tesla, Toyota, GM, Nissan, etc.) has had to develop their own manufacturing process.
Thanks Jerry, that's very interesting. I haven't done any research yet but I am interested in powering a wooden boat with electric motor propulsion. I'm interested in a motor with a lot of torque that could turn a large prop at low rpms. There may already be a commercially available electric motor for this application. As I said I haven't done any research yet. What Tesla Motors is accomplishing is very exciting.
All electric motors have a lot of torque but they also have high RPMs so you'd likely need a gear box to take care of that.
Because electric motors last a very long time (often longer than the items they were installed in originally) you should be able to find used ones for low cost.
"Electric Boat Market Takes Off in Switzerland"
Great article Volker, thanks.
Make-and-Brake engines were once popular for turning large props at low rpms. The engine ignition cycle was enabled and disabled over time and the energy during an enable cycle stored in a flywheel. When the shaft speed fell below a certain value the engine would fire again. I wonder if an electric motor could be utilized in a similar way and if there would be any advantages.
I can't think of any. Energy stored by a flywheel energy isn't free, you have to use energy to spin the flywheel resulting in an energy conversion loss, and the weight of the flywheel mechanism is likely to overcome any potential savings. It might have worked in planes because once at altitude there is very little energy required to keep the plane flying but cars have to travel up hills. It also helps that ICE have a flywheel to start with, so making it a bit heavier doesn't add the same amount of weight that a whole new device would have.
The only place that this kind of thing can work is in mountainous regions where going down hill creates more energy than the battery can store, so additional storage methods are required if you are intending to save the energy.
In the early days of the 2004 Prius, six engineers that purchased a Prius added battery packs to store additional energy. Only one had improved mpg because he lived in a mountainous region. The other five either had poorer or unchanged results. These weren't plug-in batteries as we know them today, they were just batteries added to the main battery. Back then it was thought that more battery power should equal better mpg. Turned out not to be true.
Thanks, Jerry. This is all very interesting to me.
Tesla motor is quite standard three-phase four-pole AC motor, there is nothing special about it. Basically a 100 year old invention with just minor fine-tuning. How they make PEM or power electronics is what is special to Tesla.
You can find about zillion different motor manufacturers for your boat that make just as good motors as Tesla. Trick is to combine just right amount of power, energy and size for batteries and have good and efficient inverter with right software to run the engine. While all parts are quite common and cheap combining them in "right" way without losses is not that easy task.
Note also that water + high voltages = not very healthy. You need to make your high voltage electric systems rather waterproof to make good boat motor. An emergency cutoff for batteries that physically separates the battery from rest of the system might be needed (in case there is a leak or grounding).
Salt water has a special affinity for electric gear. Do not skimp on water- and rust-proofing!!
Then triple it.
Thanks, Timo. That is very interesting. I haven't considered the potential electrocution aspect to all of this. I think I associated DC with safety, not thinking about the inverter, or the actual voltage. What are typical voltages anyway? I can't help but still be intrigued with the idea of storing energy in a flywheel - using an electric motor as opposed to a fossil-fuel-using motor. Maybe even human-assisted (pedal-powered) electric motor driven flywheel, for driving a large (high torque) low rpm prop. And yes Brian, lots of water proofing!
What kind of power you need? High voltage reduces need of high amps, but if you don't need high power then low voltage systems work just fine. Also DC motor could be safer and definitely less complex. It just wont be quite as efficient.
The thing that you mention "human-assisted" indicates that you are not aiming for high power system. If not then there are plenty of electric motors for boats already on sale. Like here: http://www.elcomotoryachts.com/products/elco-ep-motor.shtml
Just google to find plenty of those kind of pages. Electric is coming to boats too, it just is less hyped thing.
"The traditional problem with motors in cars is that prior to the Prius, large electric motors were all hand built. An order of 25 was considered a very large order. No one had ever made thousands of large motors on a production line prior to that so it is not possible to go to an electric motor manufacturer and order 2,000."
It is at least for very large AC motors. I drive trains for a living and my employer (Norwegian State Railways) are in the process of having 50 new trains delivered. Each trainset has 6 motors, thus the total is 300 induction motors which can each deliver 750kW continously.
The maker of the trains (Stadler in Switzerland) have many more customers, I'm sure they order these motors by the thousands each year.
But I suspect they are a bit heavy for passenger car use ;) they'd probably work fine in a trailer though, combined with a stack of 10 85kWh batteries ;)
I don't doubt that there are some special cases. The source for that comment was "The Prius That Shook the World" ISBN 4-526-04376-1
Con varias dudas sobre esta reciente tecnología y desarrollo de autos Tesla:
1.- Qué relación tiene Tesla Mtors con Toyota? Son una divisón, son empresas totalmente independientes o comparten avances tenologógicos?
2.- Qué tipo de transmisión manejan estos motores de Tesla, y si el PRIUS (Toyota) que tiene tecnología HSD se maneja totalmente eléctrico o sigue siendo en todos los lugares del mundo un auo híbrido?
Saludos a todos y gracias por sus comentarios...
I believe synchronous PM motors could be harder to source than the AC induction motors used by Tesla. Traditionally, induction motors has been used in heavy applications.
Permanent Magnet (PM) Motors often make a lot of sense for low powered motors (<5kW) since the magnets eliminate the need for electrical current to generate the magnetic field in the rotor. For higher powered motors, permanent magnets become increasingly more difficult to work with and are highly cost prohibitive. Plus, as motors get more powerful, the relative penalty of using current to generate the magnet field (electro-magnets) is much lower so they can still be very efficient. Hence, for high powered industrial motors and generators, 3-phase induction is currently king of the hill.
That said, I can see a time in the future when 3 or 4 phase Switched Reluctance (SR) Motors take the thrown. Mechanically, this is about a simple as you can get for a motor. The are no permanent magnets or coils in the rotor. It's a bit more difficult to design and control, but has the potential to be even more efficient than induction technology. If anyone is interested in motor operation or technology, I'd highly recommend reading about SR motors and generators.
I wonder is Tesla is considering moving to SR motors in the future. They are certainly up to the design challenge and it could help them lower costs in the long run...
I wonder if the cost of the motor is enough of a factor to be worth the expense of meeting such a "challenge". The remaining "inefficiency" that can be whittled a way is very small.
tags didn't work. Another try: thrown throne
Right. Going from 95% efficiency to 97.5% efficiency is whopping 100% increase in efficiency ;-P
No, it's a 50% decrease in inefficiency.
That would be correct use of the word. In marketing talk going from 5% to 2.5% is twice as good, so 100% increase in efficiency. That's how you get those insane over 100% figures to efficiency increase in some of the advertisements.
I think more important than the potential slight gains in efficiency for an SR motor is the prospect of fewer mechanical components and lower motor cost.
Fewer than AC induction? How is that possible, there is only one moving part in the AC induction motor? Do you mean less copper wiring?
I believe that the motor itself is nearly the cheapest item in the drivetrain already, I bet PEM costs more. If SR motor requires more complex PEM then that probably offsets the cost gain from motor itself. Even if not, the gain is small. Also power/size ratio is in question here, smaller is better, efficiency (if close) comes next to that.
Not that you shouldn't investigate the possibilities, any tech that gives same result with less cost is preferable.
I was considering copper wiring and other items associated with the rotor coils as "mechanical components". They add to cost, assembly, time, etc.
I'm still learning about these and other motor technologies myself, so I'm not exactly sure yet exactly how much of a cost, size, and efficiency difference there is between state of the art SR and Induction Motors, however my research so far indicates that an SR Motor can beat an Induction Motor in all three areas. PEM costs would likely be somewhat higher, but it seems like the cost of electronics is decreasing with time, whereas the cost of copper and iron is generally flatter or even increasing.
I can't say Tesla's R/D and retooling cost for switching to SR motors in the future would definitely be worth while (especially now when they are simply trying to turn a profit with the phenomenal Model S). However, I have to think that the SR technology is on their radar and I wouldn't be surprised if it's part of a long term plan...
I believe Tesla is following everything regarding electric drivetrains. Whatever gives you best result is least price (always a compromise).
Copper is expensive and heavy. I wonder if you could use graphene instead. Carbon is one miracle substance, it is also best conductor in room temperature that we know of in form of graphene (about 30-35% better than copper), and it is light and extremely durable in right configuration.
Cost is tied to two things: abundance and difficult to work with. graphene is good at first, bad at second, copper other way around. We can't affect abundance (at least not until we start to mine asteroids), but we can get better at working with materials. Just out of curiosity I would like to see what kind of electric motor that could produce.
Or just plain replace all copper wiring in batteries and wires with graphene. That should reduce weight quite a bit. Carbon fibers in body panels, carbon nanotube-derived chassis, graphene in wires and motor, tires, rims...
Cool idea regarding graphene. This could have huge potential if they can come up with a viable production/manufacturing method.