| T O P I C R E V I E W |
| gotwind |
Posted - 13/09/2007 : 21:17:18
I've had a very interesting email from a guy named Pete (windymiller on this forum)
He has sent me some good images of how he uses a 36v bicycle hub motor as the basis of some of the P.V.C bladed projects getting up to 10 amps@12 volts (120 watts) - I am awaiting his permission to post them here.
They are certainly not a cheap option to buy new and I believe they do use brushes - but if you know of any scrapped ones available, grab them.
Keep your eyes out guys.
Ben. |
| 15 L A T E S T R E P L I E S (Newest First) |
| windymiller |
Posted - 25/03/2008 : 23:47:10
Hi everyone who participated in the stepper motor mod
Can i first say it was probably the most frustrating ,time consuming problem ive ever had!!!.
Im sure every one else felt the same who had a go!!!.(hi fugus and weel done....i really mean it,you never gave in)
I did however have some good results in the mods i carried out to this motor,
The turning resistance (iron losses, eddy currents,coil losses)have been reduced by half(actually measured properly )
There is vertually no trace of cogging,and only a very slight drop in performance,in relation to rpm.
I did have the problem shelved for some time as i got fed up with it!!!
The way i did it was to grind off 1mm thickness across the full width of of the iron rotor(very acurately using a specially made jig )and then bond and wrap very thin plastic covered gardening wire around the full length of the rotor/coil very tightly along its length.
In effect giving the rotor a permanent shell of plastic covered steel wire.
I did think of using mig welding wire initially but i decided to have insulated metal wire instead ,hoping to eliminate some eddy currents,if there were any!!!.
I suppose you could class it as a slotless motor,as all the slots are now covered permanently with bonded wire.
I did cover the whole mod in varnish to add more containment of the bonded wire.
Overall the air gap was restored to normal by using the wire.....vertually no trace of cogging....its easier to tun than the unmodified one.
Unlikely to come apart as the iron core and windings remain stationary in operation......its the magnets that do all the moving.
Thanks for reading and cheers. |
| fungus |
Posted - 17/12/2007 : 16:00:37
I've kept the copper wire so I'll be able to take it to the scrappy but not able to use it.
A bit of progress;
I've taken the steel core off of the shaft, I hacksawed through the support arms and turned off the rest on the lathe.
Today I recieved a 150mm block of nylon to replace it, I think it'll be better than wood and easy to machine etc, I'm going to get that turned down to shape I want tomorrow and cut out the slots for the coils. |
| green energy |
Posted - 27/11/2007 : 07:40:44
Hi fungus, wondered if you are able to reuse the copper wire removed from the metal |
| fungus |
Posted - 23/11/2007 : 19:14:04
Woops- I meant 12 turns there.. On mine it was 2 strands together. |
| green energy |
Posted - 23/11/2007 : 16:20:57
Well I am going to very interested with the out come; I do not totally understand your calculations on the amount on turns of the new windings, but I guess more would be better. Was your 1000w model wired with 4 strands wound together? . I did do some very simple experiments of swiping a speaker magnet over a coil of wire sitting on the wooden bench with and without metal in the centre of the coil, without was not quite as good voltage but not that much in it. Good luck with it |
| fungus |
Posted - 23/11/2007 : 15:03:15
green_energy - the wooden alternator they made only had one set of magnets, they filled the centre of the coils with magnetite sand which provides a weak attraction.
I've stripped all the wire out now and on monday will bring the motor to get the laminations out in the lathe, then see what happens. What I'll probably do;
take the laminations off, then laminate some plywood together to make a former and mount it on the support block left over. Then I'll put it back in the metal lathe and clean it off/round it down.. I know its not too good practice to use wood in a metal lathe but it should work pretty good. Then I'll mark the slots and cut them out with a router. It originally had 15 turns/coil, if I kept the laminations it would be roughly 24 turns in the configuration I need, it'll likely be about 35 without the laminations. |
| green energy |
Posted - 23/11/2007 : 08:26:51
Hi fungus, in the dans 103 wooden rotor, is there two sets of magnets, one set either side of the windings (tried to find article). I am no way an expert but what about this magnetic flux density.
(ghurd 22/11/2007, Removing iron laminations will lower the flux density, lowering the voltage. Increasing the distance from the magnets to the laminations also lower the flux density and voltage).
I did have an earlier similar plan to remove the laminations and replace with glued layers of ply, recut the slots and rewind, I did consider if it could take the stress and strain.
I can see why on the 1000w model you may as well remove all the steel as relatively thin compared to the 2000w model, but yes I can see what you are saying it is a well built motor and possible good starting point to making good alternator. And if it spins easily 150w is pretty good
|
| gotwind |
Posted - 22/11/2007 : 17:13:06
Good luck with that Angus.
A wood cored modified alt maybe the way to go.
I see the seller still has 50 left
http://cgi.ebay.co.uk/Brushless-stepper-motor-traction-vehicle-robotics-etc_W0QQitemZ250189799643QQihZ015QQcategoryZ41981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
The Futures Green - Getwind of it. |
| fungus |
Posted - 22/11/2007 : 16:51:47
What I'm thinking;
These motors are designed for 1000w, I dont need that with a 4' prop...
Been talking to a couple people and what I think I'll do is to chop off the whole lamination structure and leave the aluminium support ring. Then I'll turn a wooden former for the coils and use a router to make some slots in it for the coils...
Even the wood-103 that the dans at otherpower made was made much more 'hastily' and didnt even have steel backing on the magnets, it made 150w..
With this stronger frame etc I think its a nice way to get all the hard parts done for making your own alternator... |
| ghurd |
Posted - 22/11/2007 : 16:38:48
Everything is a balancing act. All the stuff in there is balanced. Even if they did a crappy job of it, they do better than we can. If it would work better with less material, they would have done it that way.
Removing iron laminations will lower the flux density, lowering the voltage.
Increasing the distance from the magnets to the laminations also lower the flux density and voltage.
Increasing the resistance of the coils increases losses. Amps X amps X coil ohms = coil losses. However it would increase the voltage. Don't confuse low speed voltage with power.
G-
|
| green energy |
Posted - 22/11/2007 : 10:03:04
hello frankineto,
i did do some experimets with scewing the magnets with the rc2200-20 stepper model in relation to the rotor, and cogging seemed to get less, but the experiments were not conculsive, and when i looked at removing the original magnets and they are really well fixed, so gave up on that idea. |
| green energy |
Posted - 22/11/2007 : 07:47:01
hi ghurd,
thanks for advise, when you say the resistance will be increaed x4 or x16, will this mean, will it produce lower amps or overheat easily? i am quite a novice to electricity. also curious about why changing part will not workout. is removing some of the steel rotor and replacing with non magnetic material not going to work, again i am new to trying to make electricity from PM motors. |
| green energy |
Posted - 22/11/2007 : 07:15:29
Hi fungus.
that is what i was thinking of doing, but not removing the slots completely, maybe leave 3-4mm, and in shallow slots bond plastic or aluminum strips. then rewind the wire back round the new non magnetic material. i have already removed as much steel from the rotor as i can and am right down to the windings, in fact i just clipped one of the wires that was sticking out further than the others. removing about 2mm of the rotor makes and marked difference in the turning resistance (cant measure it but much easier to turn). i have then measured the voltage output by spinning by hand and is similar to the non modified motor. in fact i got 36v. again i cant measure this accuratly as cant tell what RPM i am turning it at in each test.
but i am not an expert on generators/motors and also thorght the iron component was important as well.
|
| fungus |
Posted - 21/11/2007 : 21:54:56
I've taken mine apart fully and am thinking of options.
I didnt know that the wind gen alternators didnt have iron in them, interesting..
What I'm thinking of doing is to chuck the stator shaft into a lathe and cut off the coils and slots completely, then glue a new set of coils on top of that, this will still keep some magnetic attraction from the iron and heatsinking which is useful but will cut down on iron losses and will be zero cogging...
I'll think a while on this.. |
| ghurd |
Posted - 21/11/2007 : 15:20:01
Changing parts never turns out well.
Redoing the wiring can turn out well.
If it has 4 strands wound together, it could be easy enough. Time consuming.
2 choices using the existing wire.
1 Cut the inputs, cut the outputs, connect them in series. The voltage will be 4X higher, but the resistance will be 16X higher.
2 Cut the inputs, cut the outputs, connect 2 strands together, connect the other 2 strands together, then connect the 2 pairs in series. The voltage will be 2X, but the resistance will be 4X higher.
It has worked out pretty well for other items I tried.
G- |
