[PStechPaul]

I have not followed all of this thread but it has my interest. I was excited about the advertised claims of great efficiency, high power, and small size and weight, back in 2007 when I first started investigating EVs and hybrid conversions. But I was put off by the high cost at forst, and then the practical limitations I soon discovered regarding the mechanical construction, and most seriously, the question of batteries. Lithium cells have become more affordable since then, but BLDC motors, and especially wheel motors, have seemed to struggle and rise and fall with inflated claims and problems.

It seems to me that there will be a huge economic problem with PM motors if EVs make serious inroads on the market, and achieve 50% of all new vehicles in 15 years as predicted by Tesla's CEO. The limited supply of rare earths will jack up the cost of BLDCs and also slow the pace of production. But the problem of fragility may be even more important, and I don't really believe most of the claims for super high efficiencies over 90%, and I don't think it's even needed.

The charts posted of torque, efficiency, and losses are contradictory or at least incomplete. The combined copper and iron losses at top speed of 900 RPM show 2400 watts, which would be an efficiency of 90% for a 24kW motor. Yet the efficiency graph claims 97%. High efficiency motors usually come with the cost of larger size and weight due to more copper and iron, but a wheel motor needs to be compact and lightweight. Realistically, the efficiency of the motor does not contribute much to the overall operating expense of the vehicle, when you consider that the 10% difference between 85% and 95% motor efficiencies, for a total power of 40 HP, is just 3000 watts. But if you can save 300 pounds, you can add a lot more batteries, or two more passengers or cargo.

I have not heard anything about a wheelmotor using three phase induction motor principles, but it may be more practical and certainly more rugged and less expensive. If you can build it with 24 poles, you can get a speed of 300 RPM at 60 Hz and overclock it by 3x for 900 RPM which is about right for most purposes. And it may be even better to use a separately excited synchronous motor design for more torque.

Finally, the best design for a wheel motor may be the incorporation of a planetary reduction drive with a magnetic clutch so that the motor will have sufficient torque for starting and hill climbing at low speeds, but be capable of highly efficient direct drive at cruising speeds where the reduction drive is bypassed. It may even be worthwhile to look at a three-speed hub, similar to the old Sturmey-Archer bicycle hubs, although hub motors generally need gearing down more than overdrive.

That's where I'd invest my efforts and money!

[lkcl]

Originally Posted by PStechPaul

I have not followed all of this thread but it has my interest. I was excited about the advertised claims of great efficiency, high power, and small size and weight, back in 2007 when I first started investigating EVs and hybrid conversions. But I was put off by the high cost at forst, and then the practical limitations I soon discovered regarding the mechanical construction, and most seriously, the question of batteries. Lithium cells have become more affordable since then, but BLDC motors, and especially wheel motors, have seemed to struggle and rise and fall with inflated claims and problems.

yeah. rare earth metals, in short supply for the batteries, rare earth metals, in short supply for the motors, and copper for the wires and motors, *also* in short supply due to the increases in electronics and electrical goods world-wide.

makes you stop and think, um, why are we in such a hurry to convert to electric cars?

It seems to me that there will be a huge economic problem with PM motors if EVs make serious inroads on the market, and achieve 50% of all new vehicles in 15 years as predicted by Tesla's CEO. The limited supply of rare earths will jack up the cost of BLDCs and also slow the pace of production.

yeah exactly. that's a good thing. it will force people to do what they should have done in the first place: redesign the vehicle according to "mass decompounding" principles (google it. it's an eye-opening article).

The charts posted of torque, efficiency, and losses are contradictory or at least incomplete. The combined copper and iron losses at top speed of 900 RPM show 2400 watts, which would be an efficiency of 90% for a 24kW motor. Yet the efficiency graph claims 97%.

yes. that's the peak efficiency, under optimal conditions. have a look at the kellycontroller 7kW in-wheel hub motor. under full load, the efficiency at low RPMs (stall torque) is s**t! it's something like 12%! and that's *normal*! the efficiency gets quite reasonable at medium RPMs, and then tails off again at peak RPM. this is *also* normal.

this is what people don't understand about electric motors, and i don't understand why they are so ignorant yet there is so much hype about "let's go electric, it'll save the planet, yaay!" it f*****g won't!

btw have you seen the pictures showing how neodymium is manufactured?? for the black market neodymium, vast areas of land in china are strip-mined, then they need hundreds of litres of high-concentration boiling acid per kg of neodymium to purify it, and the black marketeers just dump what used acid that doesn't go straight into the sky as steam right into the nearest river, killing off the local ecology for miles. and every time we say "yaay! let's buy a vehicle which has had no more attention to its design put into it other than to f*****g drop in the largest electric motor we can find, yaay!" we're enabling those scumbags (who don't have to be chinese, i should mention). it's the same category as buying child labour shoes or buying conflict diamonds.

grrrr

High efficiency motors usually come with the cost of larger size and weight due to more copper and iron, but a wheel motor needs to be compact and lightweight. Realistically, the efficiency of the motor does not contribute much to the overall operating expense of the vehicle, when you consider that the 10% difference between 85% and 95% motor efficiencies, for a total power of 40 HP, is just 3000 watts. But if you can save 300 pounds, you can add a lot more batteries, or two more passengers or cargo.

in a word... yes. which is why i've been focussing on ultra-light-weight bodywork designs, hybrids not pure EVs (2nd prototype will be a parallel hybrid), and using single motors with a standard ICE gearbox (or quad-bike CVT).

I have not heard anything about a wheelmotor using three phase induction motor principles, but it may be more practical and certainly more rugged and less expensive. If you can build it with 24 poles, you can get a speed of 300 RPM at 60 Hz and overclock it by 3x for 900 RPM which is about right for most purposes. And it may be even better to use a separately excited synchronous motor design for more torque.

ok, you definitely want to look up the LRK Torque-Max design. it was originally created for use in model aircraft, by some enthusiasts who couldn't get hold of light-weight powerful enough motors for their planes. they published the design concepts online, and that's what many companies have followed.

so you can actually build your own motor with as many poles as you want, according to the maths and equations on their site. they also have the "winding" advice, even. and yes it's a BLDC design, usually 3 phase. bottom line: you can have 24 poles if you want 24 poles and 26 magnets is a good setup, from what i gather.

Finally, the best design for a wheel motor may be the incorporation of a planetary reduction drive with a magnetic clutch so that the motor will have sufficient torque for starting and hill climbing at low speeds, but be capable of highly efficient direct drive at cruising speeds where the reduction drive is bypassed.

yes, i absolutely agree with you: i just haven't found a gearbox small enough and sturdy enough that would do the job... until you mentioned... this, below:

It may even be worthwhile to look at a three-speed hub, similar to the old Sturmey-Archer bicycle hubs, although hub motors generally need gearing down more than overdrive.

That's where I'd invest my efforts and money!

sturmley-archer... bit of googling later and following a few links... sturmley-archer gears are planetary... wow, wow! a 14-speed hub gearbox in only 1.7kg, wow! http://en.wikipedia.org/wiki/Rohloff_AG that's... deeply impressive. wow. ah i have to pursue this. thank you paul.

[ruckus]

I would suggest Googling 'neodymium' if you haven't. The 'rare' earth material used in the magnets is NOT RARE AT ALL. In fact, it is actually the most abundant of the 'rare' earth class. Most every spoonful of Earth has some.

As for lithium, it is in sea water. No shortage there.

The issue for both of these materials is production. Currently the Chinese make most of both. If EV's became the norm, production facilities would be springing up all over the world.

The whole 'rare' Earth shortage thing is oil-company propaganda.

Why should we be falling all over ourselves to switch to Electric drive???

Ever heard of the trade deficit? We currently give most of our money (that doesn't go to the war machine) to our enemies to get oil which we burn. This is pretty much the same as burning cash. DUMB! It would be MUCH smarter to put the same money into solar panels (or other energy tech). Then you actually HAVE something which continues to make you money for decades.

[PStechPaul]

Although Neodymium is indeed found all over the earth, its extraction creates many environmental problems. That's why induction motors may really be the right way to go:
http://urbanmining.org/2012/01/24/to...osium-hybrids/

Technology often tends to follow the beaten path, and such paths may be prepared by those who plan to profit hugely. There are relatively few true innovators who look at all sorts of alternatives and carefully weigh the pros and cons. It is the nature of high volume production to do a little engineering and then commit heavily in it, where better alternatives may be ignored because of immediate profit motives.

One example has been the hoopla over CFLs, which were lovingly embraced by environmentalists because of their efficiency but without much thought to the hazards of the mercury they contained, or the other problems involved in their manufacture and use. Narrow-minded zealotry led to mandates and bans which encouraged speculative buyups and hoarding of tungsten lamps. This was not the right way to encourage energy efficiency. And it inhibited the development of LED lamps, which are better, and would have become more affordable and popular if not for the CFL craze.

When government becomes too intrusive it tramples on freedom and stifles proper competition. The proper way to deal with the energy problem is to eliminate subsidies and depletion credits and apply taxes that compensate for the true cost of various forms of energy, and make it economically attractive for people to make the "right" choices.

We need to be aware of all factors involved in our choices of technology in our quest to be pioneers of energy efficiency and environmental responsibility. The oil companies are not the only ones who distort facts and hide the ugliness of reality in the name of profits and maintaining "business as usual". We must remain somewhat skeptical and open-minded and honest about bottom-line comparisons of our actions and inactions.

Ultimately, I think we will need to look at the big picture and reshape the way we live, including our driving habits, employment, and social values. But that's a much different topic from wheel motors.

[mk4gti]

Originally Posted by lkcl

this is what people don't understand about electric motors, and i don't understand why they are so ignorant yet there is so much hype about "let's go electric, it'll save the planet, yaay!" it f*****g won't!

truf. !

[JRP3]

Originally Posted by lkcl

yeah. rare earth metals, in short supply for the batteries, rare earth metals, in short supply for the motors, and copper for the wires and motors, *also* in short supply due to the increases in electronics and electrical goods world-wide.

makes you stop and think, um, why are we in such a hurry to convert to electric cars?

Maybe because what you posted is not true? Lithium batteries do not use rare earths, and AC induction motors, such as Tesla and my conversion uses, don't need rare earths, and copper is not in short supply. Copper is also recyclable, and can be replaced with aluminum in many cases.

this is what people don't understand about electric motors, and i don't understand why they are so ignorant yet there is so much hype about "let's go electric, it'll save the planet, yaay!" it f*****g won't!

The only thing that will "save the planet" is population control.

[WheelMotor]

Originally Posted by JRP3

The only thing that will "save the planet" is population control.

I am just back from Bangladesh. A country roughly 5 times the size of Belgium with a population of 15 times the already dense population of Belgium. Total chaos ! Not of any use for the WM project.
I made this picture last week, while standing in the endless Dhaka Traffic jam.



WM project is stuck again due to:
1) Unexpected price hike of RE magnets.
2) We have a working model in JMAG software, but alternative modeling software is not available as a free fully working software and cost in excess of 5000 euro for the license. As many have said here, the results of the tests, show graphs that need to be confirmed. We need a second opinion.
3) The efficinecy at 0 RPM. When the car starts to move, the efficiency is near 0 (although increases rapidly). The lack of gearing problem. Gearing is not an option, because it will make the motor overly complex and heavy.

[lkcl]

Originally Posted by WheelMotor

I am just back from Bangladesh. A country roughly 5 times the size of Belgium with a population of 15 times the already dense population of Belgium. Total chaos ! Not of any use for the WM project.

... are you sure? they could i feel make use of a much lighter-weight and lighter-powered vehicle: it's not like there's many hills, and it's not like there's all the EU regulations on vehicle design and build or anything...

I made this picture last week, while standing in the endless Dhaka Traffic jam.

superb! absolutely amazing, isn't it. it is such an eye-opener to go to these countries, isn't it? to see how people can tolerate conditions that would make less-tolerant people literally get back on the plane they just stepped out of...

WM project is stuck again due to:
1) Unexpected price hike of RE magnets.
2) We have a working model in JMAG software, but alternative modeling software is not available as a free fully working software and cost in excess of 5000 euro for the license. As many have said here, the results of the tests, show graphs that need to be confirmed. We need a second opinion.
3) The efficinecy at 0 RPM. When the car starts to move, the efficiency is near 0 (although increases rapidly). The lack of gearing problem. Gearing is not an option, because it will make the motor overly complex and heavy.

regarding 3: stall conditions is *the* serious deficiency of the entire hub-motor concept. i do not understand why people do not understand this. but do not give up! i believe it may be solvable with even just a 2-speed planetary gear arrangement, just as was suggested earlier.

regarding 2: nobody used simulations to do the LRK Torque-Max designs: they just got on with it! they did some research, calculated the equations and built one! i know the scale here is somewhat bigger, but why not try making a small one (even a 1kW one) first, perhaps for bicycles? that would solve problem 1) as well.

also regarding 1: i am serious about the lighter-weight vehicle design thing. to tackle big stuff like 1,000kg or 2,000kg cars is absolutely crazy. i can safely say this precisely because the cost of the magnets is becoming so prohibitively expensive, as it is just one sign of the insanity of taking existing *unmodified* ICE car designs and thinking "ohh, i'll just slap on some hub wheels to this 1000kg hunk of metal, that'll do" - you *can't* do that, and you should not encourage people to consider doing it either.

in other words, i really feel that the way forward is to offer companies the parts required to make "Neighbourhood EV" vehicles; Category L7e Quad-Bike "Micro-cars"; Trikes and so on, simply because it's just within the costs.

so, seriously: could you please consider - and do a fair but approximate evaluation for me - doing a 7.5kW hub motor with a 2-speed planetary gearbox built-in, based around the old bicycle concept? although it will be possible to vary the gearing of course, the high gear should be 1:1 and the low gear should be ... ooo... 2.5:1 or even 4:1 so as to provide that all-important "hill climbing" ability.

the reason for 7.5kW is because 2x 7.5kW is 15kW, and this is the limit of Category L7e. it's also perfectly well enough power to take even a quad-bike with very poor Aerodynamics up to 70mph using a CVT gearbox.... eventually

but, also: 7.5kW is going to be *affordable*. look at the cost of this: http://www.electricmotorsport.com/st...mhm602-603.php

that's the enertrac 602 (which of course is direct-drive so they have to do a 603 version which has different windings....) the cost of the enertrac 602 *including* disc brake and outer rim? $1250! and that gets you a 10kW (30kW peak) motor... and you were talking about spending $1000+ just on the raw materials of the *magnets* - that's just insanity!

so yes: please could you do an evaluation for me of the materials (esp. weight) and build cost of a spoke-based 7.5kW hub motor with a built-in 2-speed "bicycle" style planetary gearbox and forced-air cooling? let me know how much it costs for prototype units as well as an estimate for the mass-production cost, and we'll go from there - how does that sound?

/peace

l.

[ruckus]

Before you give up, please consider variations in both the winding and the diameter. Maybe the real purpose of those pimp-daddy 20" rims is to fit large diameter wheel motors.

Have you also considered making the wheel itself into the outrunner motor rotor?

Here is an article on electric 'torque motors'. They claim 1rpm is fine with the proper sensor.
http://www.rcv-srl.it/index.asp?id_s...=2&random=vero

Here is another article with some nice pictures:
http://machinedesign.com/article/tor...the-trick-0403

Here is an example torque motor.
http://www.ecvv.com/product/2405384.html
It's rpm is even lower than you require, but if you consider the 13,000nm torque, it shows that torque and rpm are inversely proportional. If you only need 1200rpm then a properly configured motor should produce 3x the torque of the same size motor configured for 3600rpm.

How many poles are you considering? 28? More is better in this case, correct?

Good luck

[WheelMotor]

Originally Posted by lkcl

... are you sure? they could i feel make use of a much lighter-weight and lighter-powered vehicle: it's not like there's many hills, and it's not like there's all the EU regulations on vehicle design and build or anything...



superb! absolutely amazing, isn't it. it is such an eye-opener to go to these countries, isn't it? to see how people can tolerate conditions that would make less-tolerant people literally get back on the plane they just stepped out of...



regarding 3: stall conditions is *the* serious deficiency of the entire hub-motor concept. i do not understand why people do not understand this. but do not give up! i believe it may be solvable with even just a 2-speed planetary gear arrangement, just as was suggested earlier.

regarding 2: nobody used simulations to do the LRK Torque-Max designs: they just got on with it! they did some research, calculated the equations and built one! i know the scale here is somewhat bigger, but why not try making a small one (even a 1kW one) first, perhaps for bicycles? that would solve problem 1) as well.

also regarding 1: i am serious about the lighter-weight vehicle design thing. to tackle big stuff like 1,000kg or 2,000kg cars is absolutely crazy. i can safely say this precisely because the cost of the magnets is becoming so prohibitively expensive, as it is just one sign of the insanity of taking existing *unmodified* ICE car designs and thinking "ohh, i'll just slap on some hub wheels to this 1000kg hunk of metal, that'll do" - you *can't* do that, and you should not encourage people to consider doing it either.

in other words, i really feel that the way forward is to offer companies the parts required to make "Neighbourhood EV" vehicles; Category L7e Quad-Bike "Micro-cars"; Trikes and so on, simply because it's just within the costs.

so, seriously: could you please consider - and do a fair but approximate evaluation for me - doing a 7.5kW hub motor with a 2-speed planetary gearbox built-in, based around the old bicycle concept? although it will be possible to vary the gearing of course, the high gear should be 1:1 and the low gear should be ... ooo... 2.5:1 or even 4:1 so as to provide that all-important "hill climbing" ability.

the reason for 7.5kW is because 2x 7.5kW is 15kW, and this is the limit of Category L7e. it's also perfectly well enough power to take even a quad-bike with very poor aerodynamics up to 70mph using a CVT gearbox.... eventually

but, also: 7.5kW is going to be *affordable*. look at the cost of this: http://www.electricmotorsport.com/st...mhm602-603.php

that's the enertrac 602 (which of course is direct-drive so they have to do a 603 version which has different windings....) the cost of the enertrac 602 *including* disc brake and outer rim? $1250! and that gets you a 10kW (30kW peak) motor... and you were talking about spending $1000+ just on the raw materials of the *magnets* - that's just insanity!

so yes: please could you do an evaluation for me of the materials (esp. weight) and build cost of a spoke-based 7.5kW hub motor with a built-in 2-speed "bicycle" style planetary gearbox and forced-air cooling? let me know how much it costs for prototype units as well as an estimate for the mass-production cost, and we'll go from there - how does that sound?

/peace

l.

I wanted to make a WheelMotor that is part of the rim. So that we could simply replace a rim/tire with my WM. This severely limits the possibilities compared to a "blanc sheet" design. But making a WM availeble to the retrofit market that could be realy bold on your car without any suspension mods and with a power of 50KW per wheel. That should be an interesting project. However ... It must remain, controller inclusive, affordable. And under affordable I mean a few 1000 $ per wheel motor. But the magnets, that can tolerate temperatures of more than 100 degree Celsius, are very expensive. If you want to see what trespassing this max temperature does to your expensive magnets, look at this chart:

Chart comes from this very interesting website:
www.ndfeb-info.com/temperature_ratings
Expensive and vulnerable magnets make it also very tough to, just make it, as a trial. And for this reason reliable modeling is a must.
Adding gearing to a retro fit Wheel Motor that has also a disk brake in the hub center is not impossible, but very complex and beyond the reach of what we affordable can fabricate.
As for your request to make a prototype of a WM with a planetary gear incorporated. Only the ingenearing of the custom made gears. I know a workshop in Egypt that can make any gears at an affordable price. But you have to design / draw it in detail and than fly to Egypt and stay there in a hotel for a few weeks. Sorry... not interested. Here in Belgium prototyping such a complex design would cost in the order of 10.000's of Euro's. I can't help you with that.
Sorting out my (by comparison super simple) water cooled gear-less WM has given me already sleepless nights.