Brushless Electric Hub Bicycle Motors

[Aaron]

I came across this concept recently. Someone here might have posted a youtube vid on this...this is one of many companies that have these and ones from different manufacturers.

Electric-Bikes.com
Go-Hub 408/48V 48-volt version for regular bikes (more torque and 25 mph)

WOW, 36mph. lol
Hub Motors, Electric Vehicle Propulsion Systems, Phoenix, RoadRunner, Sparrow Hub Motors

Vélo électrique, fabricant de vélos à assistance électrique, nos vélos électriques se démarquent des fabricants de vélos - BionX

No external motors...it is all built into the hub.

I love the concept and they're all using conventional charging and some have recovery that of course is also conventional.

With a 2 battery system, a cap bank charged from solar and/or generator action could run an oscillator to charge a bank and batteries can be switched back and forth. If the motor is off, it can be a generator while pedaling and can charge the cap, which runs an oscillator to charge a bank with radiant...or whatever permutation of these circuits you want to do.

These hub motor setups seem to be the simplest and most practical way to have a 2 battery system charged with radiant.

[lighty]

@Aaron

My friend here in Croatia owns small company which imports, service, overhaul and retrofit bikes with BLDC motors as the one you described.

One has to realize that such motor requires dedicated controller and the pulsing of stator coils require precise timing based on the position of rotor (it uses three Hall sensors). The rotor uses NdFeB magnets placed in the alternate positions around the inner radius of rotor (N-S-N-S-N-S etc.) hence the need for bridge configuration of MOSFET drivers and the requirement of precise timing in regard to position of the rotor because one have to change polarity of the current through the coils to match the polarity of the magnets which are currently in the correct position to be pulsed upon.

















Because of the "floating" connection of coil inside MOSFET bridge one simply cannot use recovery as in other pulsed type motors (like Peter's for example) which is a shame since for about a year I own a small electric scooter like this one http://www.e-vozila.com/motocikli/moped.htm also based on the BLDC hub motor. The other thing is that controller use various snubber circuits to prevent the voltage spike to kill driving IC.

Some advanced controllers allow for regenerative braking during which the motor is turned into a kind of generator and while you take current to charge the batteries the Lenz's law is accordingly causing the rotor to slow down. A good example of such controllers are the ones made by Kelly. Kelly Controller Online Shop

What I'm planning to do is to buy a broken scooter of larger size and retrofit it with stronger BLDC hub motor, then add controller with support for regenerative breaking, add LiIon batteries, replace all lamps with the LED ones and finally add one or two smaller solar panels. The next step would be to try to remove snubber circuits inside controller and try to recover all of the spikes during coils switch off phase. Anyway- for now I'm using the small scooter as the one I gave link to and I'm more than happy with it- it's completely silent (which can be dangerous for pedestrians and loose dogs), exhaust free, charging is rather fast and extremely cheap. The only thing lacking is speed of over 55 km/h (I only have 48V battery pack which I plan to raise to 72V) and the range of over 70km. As far as everything else goes I'm so used now to driving withot sound and without small engine vibrations that it's a great motivation for me to help developing electromotive systems capable of replacing internal combustion engines.

[Aaron]

hub motors

Lighty, thanks for posting that!

So as long as the control circuit allows regenerative, we can get some recovery then.

Even if the rotor slows down, that wouldn't be a problem going down hill I would imagine and would be a good safety to prevent runaway speed. Maybe a mercury switch that turns off motor and turns on generation automatically whenever the bike is pointed downhill? Of course that could be turned off if not desired for rapid up and down like off road course.

Also, on flat ground using the motor as a generator, that would simply just be good for exercise, which may be desirable?

I have a 24v scooter using 2 1.7ah gell cells at 12v each. It is old, non efficient and was rusting away for the last 5+ years. I just got it running but am having problems with the controller...I may not have hooked it all up right and one of the relays had the cover fall off but it still works even though it is all rusted

Anyway, not practical for real transportation...just going to the end of the block or something. I used to charge it up with a solar powered bicycle wheel trifilar SG and it worked great.

I'd like to get a scooter like the one you show. I haven't shopped around here yet for one but I am considering the bicycle hub motor.

[lighty]

@Aaron

Yes well there are some other facts one has to take into consideration.

Since BLDC motors have permanent magnets on the rotor they have certain advantages and certain disadvantages. First and most obvious advantage is the fact that BLDC doesn't require any kind of commutator in order to produce magnetic field in the rotor. Also magnetic field of rotor doesn't require any external power to be produced. That's good news.

The bad news is that those same permanent magnets are limiting the possible maximum speed of the BLDC depending on the battery voltage you're using to energize stator coils. The reason is quite simple- those same magnets on the rotor are generating opposing voltage in the stator windings. Now, that doesn't mean anything regarding power consumption but in order to fully energize stator coils and get maximum torque of the motor you need some amount of current. Now, if you have for example 48V battery (like I have) then the BLDC motor will produce more and more counter voltage thus progressively limiting the amount of current you can "push" through windings. All in all it will limit the maximum speed of BLDC and consequently maximum speed of your scooter or any other vehicle using BLDC.

There are two obvious solutions to this obstacle. First one is to raise power supply voltage. The second one is to make BLDC hub motor of bigger diameter in order to have bigger travel of wheel per one revolution. I considered introducing both of those solutions to my existing e-scooter but bigger diameter hub motor won't fit and I have to find place for two additional batteries. That's why I figured it would be productive to use existing internal combustion engine scooter as a basis and then re-build a wholly new electrical installation from a scratch. Of course with conventional scooters there is a problem that engine is an integral part of suspension so I would have to make new rear support for hub motor etc.

As for the regenerative braking- it's not as simple as it might seems. When you apply regenerative braking the speed will continuously fall thus not providing enough voltage for battery charging. So, one have no choice but to introduce intelligent DC-DC switcher in order to provide continuous charging voltage for batteries. Also, there is two kind of regenerative braking - the fixed value one and the adjustable one. The fixed value one will start as soon as the braking switch is pressed and it will take as much current to DC-DC switcher as it was adjusted in the hardware (or software). The adjustable regenerative braking is using the potentiometer (or more usually Hall probe) placed on the throttle control so that when you pull throttle control yourself it will serve to accelerate vehicle and when you push it from yourself beyond neutral point it will serve to regulate amount of current produced by regenerative braking thus effectively regulating the braking process more precisely. It all requires quite a bit of time and money to develop and IMO it's much easier to simply buy one of the controllers like Kelly's because they do offer both ways of regenerative braking while at the same time they can be connected to PC and a number of parameters can be adjusted as wished.


There is another solution that would probably produce bigger torque with less energy needed and possible energy recovery. I was thinking of applying the similar geometry of rotor magnets like in Johnson's motor. Ordinarily the main reason for using alternating poles configuration in BLDC is the fact that in that way one can more easy control the direction of rotation and the speed of rotation. Now, with Johnson configuration the geometry of magnets would determine the direction of rotation (so no reverse I'm afraid) but and the magnetic field would consist of number of same pole "lumps" that would provide quite a good repulsion when stator windings are energized. The speed of rotation would then be controlled simply by frequency and duty cycle. The added benefit would be easy recovery of inductive collapse during windings switch OFF time with added energy of the same pole magnetic field of rotor.

The regenerative breaking would still be possible since the magnetic field of the same pole like in the Johnson's motor would still have field strength "lumps" that would indeed induce voltage in stator windings.

I do have adequate expertise and access to appropriate tools and materials to try and produce a BLDC/Johnson's hybrid but what I lack is spare time. I do have a plan to try and produce it in the next 2-3 years as time allows.


Anyway I'm off to sleep. If you have additional questions that I cannot answer I will be redirecting them to my friend who has much more hands on experience with various BLDC and controllers than I do.

[elias]

That's Cool

Hi

I was focused on doing this too, getting a hub motor and converting my road bike to electric on its front wheel. I searched some patents to see the designs.

Lighty, the motor with Nd magnets looks good, but what about the Lindemann motor? I was planning to design a Lindemann attraction motor for this purpose which does not have the BEMF problem which limits the motor speed and has recovery options. The only issue I suppose will be is using a 10:1 planetary gear to convert the high RPMs to about 200-300 RPMs.

These are some patents:
Hub motor mechanism - Google Patents
Hub motor for a wheeled vehicle - Google Patents
Hub motor formed in a wheel - Google Patents

Maybe we can start a new thread on designing a Lindemann Hub Motor for bicycle propulsion. But First I must get some spring scales and measure the efficiency of my Lindemann motor! Jetijs' results has confused me a bit.

Elias

[ashtweth]

Guys i have another patent with a wheel EV concept , i cant post it publicly, email me ill send you the file

[Aaron]

500 mile range scooter on 1 charge

http://www.energeticforum.com/renewable-energy/2214-yoshiaki-takahashi-y-t-magnet-yt-magnet.html

500 mile range scooter on 1 charge.
If you remember the Takahashi YT magnets supposed to be much stronger than the neos we use now.

Anyway, patent included on his brushless motor that the scooter was based on.

[elias]

An Interesting Link

See This: GL

[vzon17]

Yeah I have been researching along those lines also. crystalite actually makes a motor that has brushes also. their lower range ones but those could be more easily converted to do other things as you are not limited by any electronics inside the motor. just two wires going in for the power. And they can handle mucrh more voltage than they are rated for. some of the forums I am on over volt the motor quite a bit without any problem.

[Tishatang]

Pulse PPM good for hub concept

Hi All
I got an idea for a pulse type permanent magnet motor a few years ago. It would lend itself to be compact to fit in a hub for bicycles. It could incorporate all the Bedini concepts of capturing bemf for recharge and also for regenerative braking energy back to a battery.

If anyone is interested, I will try to explain the concept.

Chris

[lighty]

@Tishatang

Why do you even ask? Explain your concept I'm sure that people are interested. I know I am.

[Tishatang]

4X3 Pulse Motor Concept

Hi Lighty

Thanks for your interest. I didn't want to start a new Thread. I just wanted to know if it was OK to post here. I am in China and sometimes it is difficult to get online.

I call it 4X3 because it is 3 stators and 4 rotors giving 12 pulses per revolution.

I was playing with a bunch of 3/8 inch neo magnets and was amazed at how they liked to assemble themselves into rod-like structures. As you add on more magnets, the poles would get stronger and stronger.
I knew about magnetic flux gates and wondered what would happen if I brought two bar magnets together with the rod of neos in the middle forming a flus gate.

I used two rectangle bar ceramic hobby magnets with like polarity facing each other in a repell position. Do not try this with neo bar magnets as they are too strong to control with your hands and you could hurt yourself. As I brought the bar magnets together in the middle of about a 4 inch long column of neos, I could see the column start to move forward but they would roll sideways and stick to my hand held bar magnets. I have a 16 inch long double edge desk ruler that has a notch cut in the middle to hold a pencil. I placed the column of neos in the notch to act as sort of a guide to prevent the rod from rolling sideways. Much to my surprise, if my timing was perfect in that the two hand held bar magnets came together at the same speed and distance, the rod of neos would accelerate through the flux gate so fast that they would fly right off the table! I knew I had discovered a cheap and easy flux gate linear motor. If I could convert this principle to a rotary version, a motor would result. I also noticed that the leading edge of the neo column only had to barely enter the leading edge of the bar magnet for the gate to open and the column would start to accelerate through.

I discovered my 3/8 neos would fit perfectly inside a 3/8 I.D. clear vinyl flexible hose that you can buy at any building supply. I stuffed a bunch of neos inside the hose and found I could bend the column in a circle. The hose allowed a slight movement between each individual magnet for them to shift and bend in an arc. So, the problem of converting linear motion to rotary motion seemed solved, at least in my mind.

I next worked on the rotor/stator relationship.
Take a piece of paper and draw a circle about 5 inches in diameter. Starting at the bottom 6 o'clock position, mark three points on the circle 120 degrees apart. These will be the leading edges of the flux gate stators. Allow 90 degrees for the end of each gate which leaves 30 degrees free space between the end of one flux gate and the beginning of another. Mark with heavy lines these three flux gates representing the bent 90 degree arcs of magnets so that they are easy to see.

Now get two popsicle sticks and glue them together 90 degrees from each other forming a perfect cross. These will represent the rotor with four poles, each pole being the two magnets in repell mode. The circle should be slightly less than the length of the sticks. By reversing the polarity of the pole magnets, the motor will turn in the opposite direction. Stick a pin through the middle of the cross and the middle of the circle. This will simulate the rotor turning through the flux gates. Bring a pole of the rotor to the leading edge of the bottom 6 o'clock position flux gate. This will be the point of highest flux resistance keeping the rotor from entering the gate. Remember, all we have to do is get the leading edge of the rotor past the leading edge of the gate for the rotor to accelerate through. As we have the bottom rotor in this position, take a look at where the other rotor poles are and what is going on in their respective positions. We notice that one rotor is in between flux gates and is basically neutral. However, we also notice that two of the rotor poles have already entered their respective flux gates and are helping accelerate the bottom pole towards the flux gate which is about to be engaged.

Because of the geometry of the 4X3 configuration, we have two flux gates acting together to help get the sticky pole through its gate! Of course, we can help the situation more by shielding the leading edge of each flux gate. Also I have read, that an ordinary ball bearing does wonders to modify flux fields. Maybe, all we have to do is add a ball bearing to the leading edge of the flux gate to get it to self-run?

If we cannot get it to self run, we can always add a solenoid coil in front of each flux gate. We could wind a trifiler coil and trigger it ala Bedini. I think a coil triggered by an optical sensor would be better. It would be timed to fire just before the rotor pole reaches it in attract mode to the solenoid. The pulse would be timed to shut off just as the pole passes the solenoid the collapsing field reversing the polarity of the solenoid which would help kick the rotor pole through the gate. You could use only one coil and fine tune it. When you get everything right, you could copy to the other two coils.
You could refine the optical sensors to move like an automotive distributor allowing you to get the best power at various motor rpms.

The trifiler wound coil works like this:
The first is DC biased to just neutralize the sticky spot opposition. This would allow smooth start up by the two poles inside the flux gates wanting to self run. Once up to speed the DC bias could be shut off. It would then be used to charge the primary battery during regenerative braking.

The second coil is the power pulse from the primary battery.

The third coil is going to the recovery battery.

I hope I made my description clear in your mind. I don't have any way to send a drawing.

Tishatang
Chris

[elias]

Your design reminds me of the 90 degree rule, combined with the muller generator design. It may work. because it seems that the total force in one direction is more than the total force on the opposite direction.
See:
MULLERPOWER.com ... advancing the legacy of Bill Muller's work in Motor/Generators...
YouTube - Steorn Toy or 90 Degree Magnetic Rule
Flying Dutchman Projects Portal - Home

Elias

[Tishatang]

Hi elias

Thanks for your reply and encouragement. I got the idea for this design maybe four years ago. But, like many other things, it got pushed to the back burner.

I wondered why the Keely motors had odd and even symmetry? After reading about Muller, I realized it was to prevent cogging. So, it was the first thing I looked for in my design.

I don't know anything about the 90 degree rule. But this is how I look at things now. Everyone seems to be preoccupied to get a self-running PPM. But what good is it if it can not produce real power? There are millions of Ebikes and scooters here in China. I can get one for less than $300 with a hub motor. They only get about 25 mile range with lead acid battery. What if we gave them something that would get them 50 mile range or more with the same battery? Millions would be sold. We would not have to wait for expensive hi-tech batteries to give a more practical Ebike.

Instead of a constant drain motor, a high torque pulse motor should deliver the goods and have recovery as an extra bonus.

Chris

[Aaron]

Bedini scooter

A simple Bedini charger will extend the range of the lead acid powered scooters without any modifications. Just charge it with radiant.