Author Topic: flywheel rotor modification / repairing  (Read 390 times)

Offline The Buddha

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Re: flywheel rotor modification / repairing
« Reply #20 on: August 09, 2020, 06:38:22 AM »
I'm pretty sure the magnets are not neutral zone in the middle and one end is N and other is S. The lines will short to each other, but the 3 magnet ones have to be which means there is enough magnetic lines around the poles as a sort of spill over.
In speakers we dont like that stray magnetism cos it distorts and does terrible stuff.
I have to check - I got atleast 1 motor with that accessible, unfortunately its 100 miles away in my other house where I was yesterday - but next run is ~1 month away.
Cool.
Buddha.
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Offline SK Racing

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Re: flywheel rotor modification / repairing
« Reply #21 on: August 09, 2020, 07:53:36 AM »
Only when you can and remember to do it, Srinath.

The idea of multiple poles in one elongated magnet is not so far-fetched. The Gauss lines are concentrated around the poles and don't affect the other poles (much). The majority of brushless motors in computers use ring magnets with typically 12 poles; - hard drive motors and also DVD and CD drives use it.

The reason I'm suspecting there are 12 poles in die GS500 is that the stator winding scheme (ABCABC...etc.) doesn't work for a rotor with 6 poles, but it does for 12 poles.

From what I've seen online, the GS500 uses the ABCABCABCABCABCABC winding scheme or pattern. That works for 18 tooth 12 pole machines. The winding scheme for 18T 6P would be AbCaBcAbCaBcAbCaBc. Capitals are for clockwise turns and lower case for anti-clockwise turns.

This is an example of a magnet with multiple poles. Source: https://www.indiamart.com/proddetail/ring-magnet-14563188130.html

« Last Edit: August 09, 2020, 08:12:02 AM by SK Racing »
You donít stop riding when you get old, you get old when you stop riding!
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1969 Triumph Bonneville 650 T120R - Sold, 1981 Honda 750F - Sold
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Offline sledge

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Re: flywheel rotor modification / repairing
« Reply #22 on: August 09, 2020, 09:57:55 AM »
The alternator has 18 teeth
Divide by 3 (the number of phases it produces)
Gives you 6 teeth per phase.
Impossible to have more poles than teeth therefore.........it can only be a 6pole. 

Twist 2 of the three output leads together and put DC across them and the single remaining lead.
Hold a compass to the end of every tooth in sequence and expect to see the following pattern.

nnS nnS nnS nnS nnS nnS  or
ssN ssN ssN ssN ssN ssN

The alternator produces up to around 90VAC.....no idea of the frequency. Based on the synchronous speed of 6 pole AC machine it may be 50Hz at around 1000rpm........but I am not sure about this. It would depend on the number of poles in the rotating field. It will be connected in star (wye) rather than delta The maths say there will be less voltage needed across each leg which means less copper is needed to produce the same output voltage and the insulation system can downgraded, meaning savings in cost and size.

This is the accepted way used by service and repair personnel to determine the number of poles in an AC winding, (and in the case of standard squirrel  cage induction motors the speed), when the info is unknown or unsure. If the machine has been rewound or the inter-coil connections broken it will also indicate any if any of the coils are reversed.

Holding a compass to the flywheel magnets will also determine the amount of poles it contains, where they are located and how they interact with each other.

I never reached the heights of machine designer but I have spent coming up to 35 years at the oily end involved with the hands on repair, maintenance and in some cases the rewinding of all forms and aspects of rotating electrical machinery....... up to 33kv and about 25 tons  .........Ask our mutual buddy Ken  :)


Happy to offer my advice.

Offline SK Racing

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Re: flywheel rotor modification / repairing
« Reply #23 on: August 09, 2020, 12:13:56 PM »
Thanks for your input, Sledge. All induction motors are asynchronous, i.e. it requires slip in order to induce current in the rotor winding. In contrast, PM (permanent magnet) motors and alternators, like the one found in the GS500 are synchronous. They operate according to different design criteria and rules.

I like your idea of using a compass to detect the poles in the rotor. Hopefully, it will tell me the number of poles without disassembling.  :thumb:


The winding scheme for the GS500 alternator should look like this: (based on 18T 12P)
I said "should", because I won't be certain until we've established how many poles there are.




Btw, you want as much copper as possible (read thick wire) to get the highest efficiency. Ohmic losses suffer with thin wire.


Just to show that with PM synchronous machines, there can be more poles than teeth;
This paraglider motor that I've designed and built has 24 stator teeth and 32 magnet poles.
Max power: 10kW
Phase termination: Delta
Propeller size: 1.2m - 1.3m


« Last Edit: August 09, 2020, 02:44:09 PM by SK Racing »
You donít stop riding when you get old, you get old when you stop riding!
1939 Panther 600cc Single - Stolen, 1970 Suzuki 50cc - Sold
1969 Triumph Bonneville 650 T120R - Sold, 1981 Honda 750F - Sold
1989 Suzuki GS500E - Sold, 2004 Suzuki GS500F - Current ride

Offline The Buddha

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Re: flywheel rotor modification / repairing
« Reply #24 on: August 09, 2020, 03:16:39 PM »
.........Ask our mutual buddy Ken  :)




I've been bugging the Ken doll on unrelated issues and trying to pester him to coming over and building some stuff for me. Will see if he does ...
Cool.
Buddha.
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Offline sledge

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Re: flywheel rotor modification / repairing
« Reply #25 on: August 10, 2020, 02:48:32 AM »
I was last talking to him a couple of weeks ago.......ask him if he has got his `concrete` worktops in yet  :thumb:
« Last Edit: August 10, 2020, 03:05:16 AM by sledge »

 

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