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In Wheel Motor ... affordable

195K views 383 replies 60 participants last post by  brian_ 
#1 ·
Hi,

I have a factory in Cairo Egypt and want to produce affordable brush-less permanent magnet in wheel electric motors.

Because of low labor cost, we could custom made adaptor sets for different cars of our customers.

We are in the planning stage and want contact with people in the US that are introduced in to EV suppliers world for brainstorming, help in developing and subsequent distribution of Wheel-Motors in the US.
 
#4 · (Edited)
The purpose is to provide the complete motor :rolleyes:. The motor is not geared. It is an inside out BLDC motor. The rotor contains the windings which is in this case fixed (to the brake clamp mounting) and the stator (or the outside of the motor) is connected to the rim and turning. They can not be delivered separately because they are made for each other (dimensions poles etc)

Since there is no gearing and no brushes or commutator the motor is very quite.

But the purpose of this thread is (at this stage) to get commercial contacts in order to set up a low volume serial production. At this moment we are developing the motor.

PS don't look to much at my avatar, it is rather "symbolic" and the real thing is totally different.
 
#8 ·
WM,
I do not represent any commercial enterprise that might want to buy your motors but I am very interested in what you describe. Can you supply any more of the details here ? Specifically the average weight of your wheel motors, output power, electrical needs, RPM range, etc. ?
 
#10 ·
Hi WM,

Yeah, this is a couple of years old. And how many do they have on the road? They gave me a quote of $35,000 each. You're going to do it for $1500? O.K. I'll buy a couple. Just need to verify performance before I write the check.

Still saying Good Luck,

major
 
#11 ·
Please read again the first post of this thread . "I want to produce"

So the purpose of this thread is to meet people to set up the business. I am not pretending that I know it all and that it's a peace of a cake.

However, before we commit substantial money and time to this, we would like to be already in contact with the market. The idea is to let the project grow as a partnership between the producer and the sales promoter.
 
#12 ·
Hey WM,

All the desire, money, business planning, partnerships, open source forums, and so on will be for naught if you don't have a competitive product. And my many years in the motor and EV business tell me that is a big problem for you.

Still say Good Luck,

major
 
#13 ·
Hey WM,

All the desire, money, business planning, partnerships, open source forums, and so on will be for naught if you don't have a competitive product. And my many years in the motor and EV business tell me that is a big problem for you.

Still say Good Luck,

major
Major,

you are a pessimist :rolleyes:. Within a few months I will be back here with a video of a prototype installed in a car. Than we speak again !

In the meanwhile everybody who has a tip for the sales promotion please post here.
 
#15 ·
WheelMotor,

The concept of a hub motor with the rotor fixed to or part of the wheel rim and the stator attached to the caliper assembly is something I've been toying with for the past month or so.

It's an outrunner design but with similar torque / speed characteristics to the Etel torque motor range: http://www.etel.ch/torque_motors (the Etel motors are actually inrunners but you get the idea)

I've started working with FEMM 4.0 to model the motor but I haven't had a lot of time lately to do it. Once I have something presentable, I'll share it here.

My goal is retrofit kits for the existing small passenger fleet - focusing on the most popular and / or efficient car models to begin with. The rotor / stator may remain the same design for many different vehicles, just the mounting arrangement may differ. It makes the most logical sense - there's no point reinventing the wheel (excuse the pun) but if you start replacing axle stubs, disk brakes, etc you end up getting involved in a lot of unnecessary design work.

It's an excellent concept with a couple of obvious challenges. First is the air gap clearance between the stator and rotor. In most BLDC motors the air gap is kept within the order of 0.5mm to maintain a high flux and therefore keep the torque constant high. With this design, you're relying on the wheel's bearings to enforce the air gap - and we all know how shaky wheel bearings can get over time/miles. The rotor may start rubbing on the stator leading to a quick demise. You could have a large bearing ring between the rotor and stator also but this may introduce unnecesary losses and may make tyre changing tricky.

Secondly is the issue of space. On most larger cars with alloy rims of at least 14" and standard brake disk/calipers this shouldn't be too much of an issue. However, if you want to convert a "smart car" with tiny rims, you'll need a more custom arrangement like pushing the magnets deeper into the tyre rim.

I'm an electronics / computer / HV electrical engineer so I've been working on the drive electronics too. We really need someone who's had experience programming automotive computers for stability control, etc since the hub motors need to work in unison and therefore need to be integrated into one drive control unit.

Cheers WheelMotor, hopefully we can get the ball rolling on this one.

Sam.
 
#16 ·
In the running !

Hi Samborambo,

Happy to hear you are less pessimistic than Major !

I am devoting all my time now to getting a prototype on a car asap. The coming week I will try to have a low cost FET motor controller with Hall sensors finished.

A cooperation between us could be fruitful. My approach is to make a complete set of 2 Wheel Motors + controller manufactured in Low Cost Egypt available at a price level in the range of the classic in board DC motor + controller.

I could produce and you commercialise. Exciting days ! Lets see how far we get .
 
#17 ·
I'm curious now - you'll have your drive design completed in a week? Can I see what you've got so far?

MOSFETs wouldn't really be suitable for a high voltage (~300V) design because of the ohmic losses. Drive systems in this power range almost exclusively use IGBTs due to the lower losses. IGBTs' losses (volt drop) are proportional to current whereas MOSFETs' losses (ohmic) are proportional to the current squared. You can get suitable MOSFETs in that power range but they won't perform as well. The drawback with IGBTs is more complex transistor driver circuit (require negative bias for efficient turn-off).

These IGBT six packs are specifically designed for hybrids and would suit individual wheel motors:

http://www.infineon.com/cms/en/product/channel.html?channel=db3a3043136fc1dd011370f45ed90441

I think we need to turn conventional motor construction on its head in a few respects. Most industrial electric machines are designed for constant power / speed applications. That's where most development has happened over the past few decades. I believe there's a lot of room for pioneering work in automotive traction motors.

I'm keen to use aluminium tape or foil for the magnet wire instead of copper for two reasons. First, aluminium has a higher specific heat capacity (temperature rise for a given mass and heating energy) so the motor will have 16% greater peak power including the weight reduction. For an equivalent conductive CSA, aluminium is HALF the weight of copper. The drawbacks of aluminium are 60% greater volume for equivalent copper CSA and thermal deformation - both of which can be designed for. Using tape or foil, the winding window would be almost the same area as copper since copper wire typically has a winding factor of 70% and even less for litz wire. A drawback of wide tape or foil could be increased eddy current losses in the windings. I haven't calculated the losses that eddy currents introduce but even in the worst case scenario, chokes can be added to reduce the effect.

The reduction in weight would greatly reduce the impact on unsprung weight. I'd like to aim to keep the rotor and stator together under 10kgs.

The second idea I had is to incorporate the ability to switch the configuration of the torque motor. For instance, with a 36 finger stator, 12 parallel x 1 serial per phase for high speed / half torque and 6p2s per phase for lower speed / full torque. This would keep the BEMF within a manageable range and increase efficiency of the IGBTs. Think of it somewhat like an electrical gear box - you're altering the turns ratio of the motor windings. The transition would be seamless since its the controller causing the switching based on speed thresholds and then halves or doubles the current.

Wheelmotor, please post up your design so far for both the motor and electronics. You said you want to participate in open source development of the motor. Please let others contribute too.

Sam.
 
#19 ·
I'm keen to use aluminium tape or foil for the magnet wire instead of copper for two reasons.
Use copper clad aluminum wound between nomex (thin flat sheets)... that'll work just fine for the wire (flat wire being the OBVIOUS necessity here... but good luck finding it in egypt... seriously... good luck)

I'd use an electromagnetic braking DC motor... ie. a controller MUST be custom designed to permanently drive a variable (based upon braking power) voltage that would exert resistive forces on the stator and coils (DC not AC voltage... unless you wanted to get fancy with electro-anti-lock braking)

Neodymium is a must (did I say must must)

Sorry for my non-engineering help, this is more a hands on help here. I can help you with your FEMM btw samb, very familiar with the program.
 
#18 ·
Time is money

High Samborambo,

Happy with your contribution in this discussion !

The reason I did not shared openly my progression is that I felt no input (only scepticism :() from the other members at first. Second point is that I have no ambition to teach, I want to do business. Therefore I want an approach inspired by practicality.

So far:
Thanks for the tip about Insulated Gate Bipolar Transistor. I am 52 and my knowledge of electronics is getting a bit rusty.
I ringed to the Distributor of Infineon in Brussels where I asked them for this "six pack". They said they did not followed this item because of infrequent demand, but they should investigate. They could/would not give a price.
However, I was not anticipating 300V. Normal should be 8 x 12 volt = 96 v. If we start with 8 V Trojans of 2 banks in parallel ... it gets bulky to get to even 150V.
For what the controller is considered: I will see what I can find here in Belgium and than start from there. If I can't get it working within 10 days or so, I can always postpone this item and by simply a Kelly controller.
http://www.kellycontroller.com/mot/Brushless-DC-Motor-Controller.html

For the wiring I was indeed intend to use aluminium, because as I see it now, unsprung weight is the (only?) possible hurdle to success.

For what is considered the total construction of the wheel motor, I gave up on the idea to put the magnets in the rim and use the brake caliper to hold the rest of the engine. Because of the huge forces that the magnets will apply to the stator of the engine, it will be very difficult to change a tire + rim by the side of the road in case of a flat. The magnets can be destroyed if they smash in to the stator. Also the aluminium rim can flex a few mm and the airgap must be to big. Better to have the assembly under control in the factory.
An other possibility is a custom made 2 piece rim.

A 36 finger stator ??? Have you measured the dimension of 1 coil with a 3 mm thick wire? and the brake caliper?

I don't want to go open source anymore. Because the feedback in this forum is to theoretical and to far from practical reality.

However Samborambo I will PM you about how we could cooperate.

Please let this thread be only dedicated to commercial contacting and brainstorming.
 
#22 · (Edited)
Re: Time is money

High Samborambo,

Happy with your contribution in this discussion !

The reason I did not shared openly my progression is that I felt no input (only scepticism :() from the other members at first. Second point is that I have no ambition to teach, I want to do business. Therefore I want an approach inspired by practicality.

So far:
Thanks for the tip about Insulated Gate Bipolar Transistor. I am 52 and my knowledge of electronics is getting a bit rusty.
I 'rang' the Distributor of Infineon in Brussels where I asked them for this "six pack". They said they did not 'carry stock of' this item because of infrequent demand, but they should investigate. They could/would not give a price.
However, I was not anticipating 300V. Normal should be 8 x 12 volt = 96 v. If we start with 8 V Trojans of 2 banks in parallel ... it gets bulky to get to even 150V......
.....For the wiring I was indeed intending to use aluminium, because as I see it now, unsprung weight is the (only?) possible hurdle to success.

For what is considered the total construction of the wheel motor, I gave up on the idea to put the magnets in the rim and use the brake caliper to hold the rest of the engine. Because of the huge forces that the magnets will apply to the stator of the engine, it will be very difficult to change a tire + rim by the side of the road in case of a flat. The magnets can be destroyed if they smash in to the stator. Also the aluminium rim can flex a few mm and the airgap must be to big. Better to have the assembly under control in the factory.
An other possibility is a custom made 2 piece rim.

A 36 finger stator ??? Have you measured the dimension of 1 coil with a 3 mm thick wire? and the brake caliper?

I don't want to go open source anymore. Because the feedback in this forum is to theoretical and to far from practical reality.

However Samborambo I will PM you about how we could cooperate.

Please let this thread be only dedicated to commercial contacting and brainstorming.
Hi WheelMotor...I am Dave here in Singapore, have been following your discussion with Samborambo - a fellow countryman of mine and Tech about a wheel motor design.

I am an Designer/Engineer/Architect working out of Singapore and have been looking and documenting the possibilities for this type of project for a while now. Lets set some parameters. Lets us not use last years technology so please dismiss the idea of using lead acid batteries...infact for this part of the design process, forget about what batteries are used but lets get out of the low voltage design..not less than 144 volts and look upwards to even 288v even higher, at this stage let us not restrict ourselves by mere battery voltage.
As for the physical layout of the wheelmotor....is does not have a disc brake, so why even mention it. And it will have a alloy dismountable wheel, just like modern cars have, not a wheel that is the rotor, so there will be no removal of the rotor to change a tire.
Using really good magnets is a must, nothing but neodymium, like Samborambo said it is a must, must ok...as for assembly of the finished rotor onto the stator, that would be a once only factory thing, never to be dissasembled on the side of the road to change anything, and with all wiring accessable from the rear of the stator which would be fixed to the existing hubs of the vehicle.
And your reference to fixing the engine to the brake caliper does not make sense - it is not a engine, it is an electric motor and there are no brake calipers, regenerative braking will be employed thru out and there will be no flex of the outer rotor against the inner stator because the circular construction of the rotor is stronger than you think.

Any way I am going back to my day job and will catch up with you all later...I will be up Egypt way later this month, perhaps we could see each other Wheelmotor....gee I like my job...lol free travel to exotic places with sunbaked beaches with cool drinks in the shade......nah make that hot deserts....with warm canned drinks under a hot hot sun.....lol
ciao for now..
 
#21 ·
Re: Is the soup worth the cabbage ?

Hi Tech,
Is the skin effect in the CCAW sufficient at the low frequency of only a few 100 Hz to justify its use ?
well copper clading offers a few benefits to just straight aluminum. Aluminum oxide will build up at terminals/any air exposure unless it's clad. The reason this is bad is aluminum oxide is actually electrically insulative (... actually besides diamond it's the most electrically insulative material on earth).

It's worth it in the long run but there are a number of ways to terminate aluminum wire safely without risk.

If you can find a cheaply priced CCAW flat wire I'd use it though... it's also quite a bit more conductive per cross section than just straight aluminum (10% more to be precise).
 
#24 ·


And for under $1500 each. Including controller.
hey thanks for the link, but after seeing other things come out of china..here in singapore, that are supposed to be high tech...I doubt I want to be buying something that looks like that....there appears to be too much weight hanging outside the original flange depth of the hub...I have seen inside chinese DC automotive motors here in singapore and they are not that pretty, their controllers are pretty basic too...understand this...China is going EV crazy...but not in a high tech way...no thanks...even for the price of $1500, besides it takes all the fun out of learning an doing for one's self....
 
#26 ·
Non technical problems

I agree with you Dave about the construction of the WM as a closed unit for many obvious reasons.

At this moment I am only blocked for legal reasons. We came also to the conclusion that letting the brake (disk or drum) in place will be impossible. Bolting the WM just beside the brake drum like GLEVP suggests here in the picture is ehum ... not acceptable. So our initial approach was to built the WM around the brake. This will not go because of heat and dust produced by the brakes.

This has provoked a big legal obstacle for commercializing the WM. I don't see me suggesting a client to remove the brakes from his car (not even on 1 axle) and rely on regenerative braking only. In Belgium it's out of the question. People can not change anything on their car because the insurance will not cover you, in case of an accident, if your car is not conform the original and they can prove that there might be a link between the alteration and the accident. Like in the case they find out you removed the disc brakes from your car and replaced them by some novel electric stuff. I actually never hoped to commercialize in Europe from the start. In the US it could go, but the legal consequences must be considered.
 
#27 ·
Re: Non technical problems

I agree with you Dave about the construction of the WM as a closed unit for many obvious reasons.

At this moment I am only blocked for legal reasons. We came also to the conclusion that letting the brake (disk or drum) in place will be impossible. Bolting the WM just beside the brake drum like GLEVP suggests here in the picture is ehum ... not acceptable. So our initial approach was to built the WM around the brake. This will not go because of heat and dust produced by the brakes.

This has provoked a big legal obstacle for commercializing the WM. I don't see me suggesting a client to remove the brakes from his car (not even on 1 axle) and rely on regenerative braking only. In Belgium it's out of the question. People can not change anything on their car because the insurance will not cover you, in case of an accident, if your car is not conform the original and they can prove that there might be a link between the alteration and the accident. Like in the case they find out you removed the disc brakes from your car and replaced them by some novel electric stuff. I actually never hoped to commercialize in Europe from the start. In the US it could go, but the legal consequences must be considered.

Hey Guy...that is your name right...WM...(hehehe)..saw your posting on MyOwnHybrid....I understand your situation in Belgium, the same in Singapore here....must be original or no insurance, where as in NZ and OZ and the States....certification of a modified vehicle will be accepted, and EV's and regenerative braking are not novel...and we are not making 'novelty' electric car thingys.
Remember Tesla made electric cars over a hundred years ago in Europe and we are just heading back there are being over powered by the Oil magnates and the ICE's for the past 100 years.... Any way if we have to give these motors friction brakes that work, and if you want to retain the original stub axle on the front suspension then we have to look at locating the stator assembly behind the disc brake assembly and make the rotor out of ceramics so that heat does not bother the magnets and make the stator and rotor really narrow..and see if that works. A similar set up could be designed for a fixed rear axle for a rear wheel drive vehicle or fixed around the stubs of rear wheels for a front wheel driven vehicle...if you want to keep the brakes, then work around them.
For me personally - I am going to figure how to reuse the BEMF from those motors without throwing out all that wasted energy, I would rather go with regenerative brakes then play with friction brakes...
 
#28 ·
every day brings new questions

*****,

I want to target the retrofit market.

Sorry, I have my bad days too. (about the OS aproach) Will be good boy and share.

Batteries are actually not my concern. I want to concentrate only on the WM.

As far as Vasco of MyOwnHybrid's blog is concerned. He too suggests that "the mechanical brakes will not function except for parking". Because he also wants to encapsulate the drum brake inside the WM.

Our ruff calculations show that we don't need to worry about Torque. Because of the big Torque Arm of the radial constructed WM and the nature of the BLDC motor, Torque will be plenty.

So in the last days my attention has shifted from the electromechanical problems to the following :

1) How to shield the motor from Ferromagnetic debris that could lay on the road and the ferromagnetic dust that is produced by the brakes?

2) How to make the WM adaptable to all kind of vehicles with disc and drum brakes ?

3) Can a company legally commercialize a product that suggests that you remove the original friction brakes from your car ?

4) If we start from a blank sheet WM/brake construction what do we do with the excess electric power generated by heavy regenerative braking? Like Guy mentions here: http://myownhybrid.wordpress.com/2007/12/10/motor-design/ This could implicate that we have to waste that energy because we get "to much to fast" .

5) How to get rid of the heat that the friction brakes generate inside the WM, in case we still consider (for legal reasons) to build the WM around the brake ?
 
#29 ·
Re: every day brings new questions

*****,

I want to target the retrofit market.

Sorry, I have my bad days too. (about the OS aproach) Will be good boy and share.

Batteries are actually not my concern. I want to concentrate only on the WM.

As far as Vasco of MyOwnHybrid's blog is concerned. He too suggests that "the mechanical brakes will not function except for parking". Because he also wants to encapsulate the drum brake inside the WM.

Our ruff calculations show that we don't need to worry about Torque. Because of the big Torque Arm of the radial constructed WM and the nature of the BLDC motor, Torque will be plenty.

So in the last days my attention has shifted from the electromechanical problems to the following :

1) How to shield the motor from Ferromagnetic debris that could lay on the road and the ferromagnetic dust that is produced by the brakes?

2) How to make the WM adaptable to all kind of vehicles with disc and drum brakes ?

3) Can a company legally commercialize a product that suggests that you remove the original friction brakes from your car ?

4) If we start from a blank sheet WM/brake construction what do we do with the excess electric power generated by heavy regenerative braking? Like Guy mentions here: http://myownhybrid.wordpress.com/2007/12/10/motor-design/ This could implicate that we have to waste that energy because we get "to much to fast" .

5) How to get rid of the heat that the friction brakes generate inside the WM, in case we still consider (for legal reasons) to build the WM around the brake ?

lol oh you have been naughty boy Guy...but we will forgive you.....eventually...mean while have fun with your WM around the rear axle of a vehicle that only uses it parking brakes....cause that is what MyOwnHybrid has set out to do, as for the BEMF....why not charge batteries with it....that is what it is good for...duh....
 
#30 ·
duh ... ?

If you want to rely on your WM for Regen Braking in case of an emergency stop, you will need to absorb (charge) like 200 (and more) Amps / sec. If you want to push 2 or 300 amps in your battery you will need big Voltage at very high load to get that in your battery. I have no idea how that will go in real live (how the WM will perform as a generator) or how the battery will survive that mistreatment.

It is not a coincident that GM is looking for Ultra Caps to put in the new Volt in order to blitz charge the regenerative braking power away in a matter of seconds !

Unfortunately they are very expensive at the moment and that's the prob Dave !

You can read it here:http://www.autobloggreen.com/2008/0...rcaps-with-li-ion-batteries-for-next-gen-e-f/

See animation here: http://www.youtube.com/watch?v=Fk7xbcnzxks

http://myownhybrid.wordpress.com/2007/12/10/motor-design/#comment-283
 
#31 ·
Re: duh ... ?

If you want to rely on your WM for Regen Braking in case of an emergency stop, you will need to absorb (charge) like 200 (and more) Amps / sec. If you want to push 2 or 300 amps in your battery you will need big Voltage at very high load to get that in your battery. I have no idea how that will go in real live (how the WM will perform as a generator) or how the battery will survive that mistreatment.

It is not a coincident that GM is looking for Ultra Caps to put in the new Volt in order to blitz charge the regenerative braking power away in a matter of seconds !

Unfortunately they are very expensive at the moment and that's the prob Dave !

You can read it here:http://www.autobloggreen.com/2008/0...rcaps-with-li-ion-batteries-for-next-gen-e-f/

See animation here: http://www.youtube.com/watch?v=Fk7xbcnzxks

http://myownhybrid.wordpress.com/2007/12/10/motor-design/#comment-283

hey Guy....WM...please let us learn to crawl before we start to run...let us get this WM sorted out, and if we use regenerative braking, let's wait a few months. As for thr links you listed....these are from companies whose aim it is to stall the development of EV's as long as possible...with talk of great command centers...PCCs to control the voltages between the Super Caps, Li Ion batteries and the motor/generator....yeah all big talk...


mean while there are grass roots levels like this bicycle from Japan where they have worked on regenerative braking for their products and it works
http://www.engadget.com/2008/07/07/panasonics-lithium-vivi-rx-10s-electric-bike-does-regenerative/ and let is not forget that we will not be making mega hp motors first time out, so let this technology grow as we need it ok...

I know all the literature out there tell's us it is not easy to capture 'all that power' created under braking....but then all that takes is smart management...and I am sure we can work on that...

Have you see RC model cars racing at 50 km/hr come to stop in a matter of meters....well guess what they use.....regenerative braking....not disc brakes...we can get there ok...do not let the thought of costly Super Caps put you off the possibilities.
 
#32 ·
I just stumbled upon this thread while looking for a reliable source for wheel motors. I certainly applaud your "can do" attitude.

I have been researching the viability of a reasonable priced electric motorcycle. There are several out there already but at a cost that puts them beyond the marketplace. While I love the idea of having an electric version of my Honda Accord I think we all know that EV's are going to cost more than the average person can afford, barring some revolution in battery technology.

I think a very logical step in the future will be that we many of us may need to downsize are vehicles to what we absolutely need. A quick look at any third world country will reveal that two wheels are more popular than four and it has nothing to do with being out in the fresh air.

Retrofitting a motorcycle with a wheel motor might be less problematic since you can manufacture the entire wheel/axle assembly. With optional spacers you could bolt a single wheel motor/hub on to almost any motorcycle frame. By using an external disc brake, which is popular on many motorcycles already, you could solve your heat and dust problem.

What I am looking for is a wheel motor in the 4 - 5Kw range, running on 60 to 96 volts with a maximum speed of 1200rpm. Regenerative braking, even if it is only capable of mild braking would also be a plus.

Your projected price of $1,500 might be a little expensive for my project but the motor I would be looking for would be substantially smaller too. Many backyard motorcycle EV tinkers have been using a standard DC motor in a standard motorcycle engine/chain combination. This is very cost effective but not as efficient. It also takes up space in the frame that could be used for batteries.

Good Luck with your endeavor.
 
#33 ·
thank you rj for reading and understanding the topic...I am on a couple of similar forums and the development of a wheel hub motor is being looked at from several sides and for smaller projects, like 2 wheel vehicles it seems we do not have that much mass to stop in a hurry, but the heavier the vehicle, the more need there is for another form of positive braking besides regenerative braking...at present, so yes a disc brake on a motor cycle is quite acceptable as long as it can be linked to the wheel hub motor, and drum brakes are being proposed for full size vehicles with the hub motor between the drum and the rim of the wheel leaving the brakes to work regardless, untill we can develop a regenerative system that takes all that other wise spent energy created when one wants to stop..into reusable stored enegry. Yeah all takes time to develop.

ciao for now...
 
#37 ·
A (powerful) hub motor for a motorcycle is pretty ambitious when you consider weight. The effect of unsprung weight is proportional to the ratio of the unsprung weight to the total vehicle mass. So for a car or truck, this can be managed when designing a hub motor since the ratio of unsprung weight is small compared to the total vehicle mass. Not so with a motorcycle.

I'm working on a motorcycle conversion at the moment. Aiming for 25kW and 200km+ range so it'll be a heavy bike but not much more than an average 900cc touring bike. Full fairing is a must as bikes typically have a lot more aerodynamic drag compared to cars which affects high speed losses more significantly.

Sam.
 
#39 ·
A (powerful) hub motor for a motorcycle is pretty ambitious when you consider weight. The effect of unsprung weight is proportional to the ratio of the unsprung weight to the total vehicle mass. So for a car or truck, this can be managed when designing a hub motor since the ratio of unsprung weight is small compared to the total vehicle mass. Not so with a motorcycle.

I'm working on a motorcycle conversion at the moment. Aiming for 25kW and 200km+ range so it'll be a heavy bike but not much more than an average 900cc touring bike. Full fairing is a must as bikes typically have a lot more aerodynamic drag compared to cars which affects high speed losses more significantly.

Sam.
We are all taught that unsprung weight is bad but honestly, how bad. Many older Harleys had no suspension at all in the back at all (hard tails). Most agree that for hard acceleration, unsprung weight can lead to wheel hop and reduced traction, but with 25kw that shouldn't be a problem. If rough roads are common where you drive than you may need to beef up your axle to handle the extra stress but that should be about it.

I'm curious what you are planning on using for batteries to achieve your 200km range. Most motorcycles need at least 4 or 5kw to sustain 100kmh. A quick calculation would seem that you will need 8 to 10kw of storage capacity with a C2 discharge rate. Lead acid is out of the question due to weight and anything else would be in the $10,000 range.
 
#38 ·
Thanks JRP, it might be worth a look. It seems a little underpowered but the price is right, at least for experimenting with. As to Dave's comment, newer brushless technology would be prefered but I think that is why many of the commercially available EV motorcycles cost over 10K. As to brushless lasting longer, let's face it an electric motorcycle is not something that we expect 100,000 miles from anyway.
 
#40 ·
Whoa.

Hard tail choppers have no consideration for unsprung weight in the back, as there are no springs in the back.

Ride quality is at its worst possible, because all the weight is carried by and directly transferred to the frame.

Unsprung weight is only a consideration when suspensions are involved, no?
 
#41 ·
What range of power will your motors take? Will you have braking included? Have you identified the controller to co-ordinate the motors and can it perform the function of providing a differential for turns?

My interest is in promoting electric conversion for older collector cars as the hard parts are no longer available and/or affordable. Most of these cars had engines rated under 100hp. Most of them are not used as everyday drivers. Rotors totaling from 6 to 15KW should work well for these vehicles. Maximum RPMs run about 1000 for 55mph ability. I have a different product that I sell to ato repair shops. I'm trying to get those shops interested in the electric conversion market. Lack of a usable hub motor is one of the major problems. Hardened transmission gears and differentials are very expensive for these cars so eliminating the transmission entirely is a major plus.
 
#42 ·
Regarding your possible development, are we talking a similar product as the PML Hi-PA drive, when the motor and controller are all in-wheel, and only the battery is in the engine compartment? If so, what gearing-equivalent ratios are you intending to incorporate into the unit? What max speed are you enabling, and what is your expected specifications (weight, torque, regen, etc.)? At what point, based on your speculation of $1,500 per wheel, will you begin to see volume price reductions, ie: once your factory hits 100,000 units, price drops to $1,200 per unit. I am interested because I am in the process for starting a company for EV conversions, and wheelmotors have a great prospect for this. The PML Hi-PA offers 85% regen down to 0 impulse, based upon thier wheelmotors and supercaps to capture the energy, do you see your device having the same (or better!) ?
 
#43 ·
In Wheel Motor ... affordable ... but where to start ?

Hi, Happy with the last 2 reactions !

GKnightBC,
Yes PML is definitively the big example! I am not intent to include the controller in the WM. I don't see an advantage in it and it doesn't really matter where the controller is located. Gearing ? No gearing ! The motor is producing tork directly on the wheel itself. The nature of the BLDC motor is that it will be great for Regenerative Braking. I don't think that 100.000 units/ ??? Month / year is a very realistic perspective.

The real problems that keeps me busy at this moment are:
We came to the conclusion that in order to place the motor in the wheel, the brake has to be removed. This is legally a big problem. Also because I target the conversion market, there is to much diversity of vehicles. In order to make it commercially feasible I need a commercial contact in the US market and a first big volume car that we could target for conversion. Collector Classics are a great target market. Let's assume we take these sort of cars. So we speak about rear driven / drum break cars. It could be possible that we let in that case the drum brake in place. This makes the project already more realistic.

MylesJ
Differential in left right speed is no problem at all because the wheels are totally independent. To limit the slip it is easily possible to read the wheel RPM from the Hall sensors and from there on to limit the current to the slipping wheel, if we want to simulate a limited slip differential.

But !!!
We have to be realistic and set (gradually) the order of priority of the problems. The wheel motor was already used by Ferdinand Porsche in 1896 !!! So technically there is not an insurmountable problem. No problem of enough Tork, efficiency etc etc. Till now the Battery was the problem.
And for our "Affordable Wheel Motor" project the BIG problem is Commercially and Legal in the first place. So before we start a discussion about how much % regenerative energy we can recuperate when braking we should deal with the issues: How must the WM be Legally so that we are allowed to commercialize it in the US. Who is placed to commercialise it ? What car are we targeting ? etc etc.
 
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