Cyclone motor lamination thickness ? max rpm ?

[jk1]

With the geared 48v 1200w cyclone motors, what is the stator lamination thickness and hence maximum voltage you could put in the motor without to many eddy current losses ? would they work at 60v if the motor did not overheat?

Jk1

 

[cheekybloke]

With the geared 48v 1200w cyclone motors, what is the stator lamination thickness and hence maximum voltage you could put in the motor without to many eddy current losses ? would they work at 60v if the motor did not overheat?

Jk1

hi jk1
jim from AFT is doing research into running cyclone motors at 60v,
the main overheating problem is that there is no heatsink/thermal goo inside the casing,all the heat has to radiate through an air space to get to the casing.
the upgraded cooling fins really help but ideally the inside would need dealing with.
also getting the motor casing off is a job in itself.you would have to make a puller or fill the casing with the windings inside it.
http://www.af-tech.com.au/Products_Ebikes.html
darren

 

[John in CR]

With the geared 48v 1200w cyclone motors, what is the stator lamination thickness and hence maximum voltage you could put in the motor without to many eddy current losses ? would they work at 60v if the motor did not overheat?

Jk1

the main overheating problem is that there is no heatsink/thermal goo inside the casing,all the heat has to radiate through an air space to get to the casing.

Darren,
Actually Jk1 is spot on with his question, because the main overheating problem is making too much heat. So he's looking for info that is more direct in evaluating efficiency and quality for comparison of one motor the the next. I'd add what is the pole count to the question list, since with a good design then a low pole count and nice thin lams can combine for high efficiency. The less heat you make, the less heat there is to dissipate, and higher voltage is an easy route to more power, which is much better than the typical route around here of throwing more current at the motor. "Volt up and gear down", but if you have crappy thick lams and a high pole count, you can't.

 

[jk1]

Does anyone know the thickness of the laminations and pole count of the cyclone motors ?

 

[Miles]

http://mrbill.homeip.net/albums/cyclone_motor/

 

[jk1]

i had a look at the photos and it seems their is 98 1mm laminations from that photo?

And is the pole count the count of magnets on the rotor ? if so then their is 8 poles ?

So what does this mean? what is the maximum RPM you can use on this motor ?

 

[Miles]

If there are 98 laminations on a 2 inch stack (its a scale ruler, no metric) they're 0.5mm laminations.

Yes 8 poles.

Fundamental frequency is rpm / 60 * number of pole pairs.

For 0,5mm laminations it would be preferable to keep the frequency below 250Hz, I think.

 

[boostjuice]

So you are suggesting 3750rpm max Miles?

 

[Miles]

So you are suggesting 3750rpm max Miles?

If you want a figure without doing any testing, yes...

 

[jk1]

So this 3750 rpm, what does it mean ? after that point will the eddie current losses start increase a lot faster ? is it like a cliff or gradually increase after that?

How many KV are the 48v 1200w motors ? what rpm will they do at full rpm unloaded ? what RPM does the peak power occur at 48v volts ?

As a rule of thumb does Maximum power then occur at what 50% of the unloaded maximum rpm ?

So is it right to say, we need to make sure the point where the motor reaches MAX power must be bellow 3750 RPM ?

 

[Miles]

So this 3750 rpm, what does it mean ? after that point will the eddie current losses start increase a lot faster ? is it like a cliff or gradually increase after that?

It's just a general guide for that lamination thickness, if you care about peak efficiency. Parasitic losses have two major components - hysteresis losses and eddy current losses. Hysteresis losses have a close to linear relationship with the fundamental frequency, eddy current losses increase as the square of the fundamental frequency. Only eddy current losses are affected by the lamination thickness (they go up as the square of the lamination thickness). So, the critical point is the frequency that eddy current losses start to dominate over hysteresis losses, for a given motor.

 

[Miles]

As a rule of thumb does Maximum power then occur at what 50% of the unloaded maximum rpm ?

So is it right to say, we need to make sure the point where the motor reaches MAX power must be bellow 3750 RPM ?

Maximum theoretical power is at half of no load rpm. Achievable peak power will be less, at a correspondingly higher rpm. I'd suggest that the speed band between max. continuous power and peak efficiency is the one to concentrate on.

 

[jk1]

Hi Miles, I was reading on some other thread and I heard the cyclone motor is 100 rpm per volt


So I have done a table for each voltage

Voltage 24 36 48 60
Motor rpm unloaded 2400 3600 4800 6000

Peak power RPM 50% of unloaded rpm 1200 1800 2400 3000
Here is the dyno chart for it
http://www.cyclone-tw.com/dc24.htm

So with the limit of 3750 RPM on the motor,

so peak power is at 50% no load speed after that the torque drops off a hill anyway so you wouldn't want to run it at such high rpm anyway. yes its more efficient but their is not much power their.

At 60v their is still 750 RPM (above 3000) you can move up the efficiency curve , so you could still operate at nearly the sweet spot, in between the Torque peak RPM and Efficency peak RPM, so lots of power and good efficiency. So do you think it will work ok at 60v in regard to the eddy current losses ?

 

[Miles]

If you load to 50% of unloaded speed, the efficiency is close to 50%.... In practice, peak power (for a given time) is limited by the ability to dissipate heat. Torque is inversely proportional to rpm - maximum at stall falling to zero at no load speed (if not limited by the controller).

I think 48 Volts is probably a better compromise but the only way to really find out what the parasitic losses are is to test and see. I'm not sure I'd trust that dyno chart.

 

[boostjuice]

Kv is ~150 for the "650/1200W" epicyclic/planetary gear-motors. Not ~100.

In my experience, they will run continuously without overheating at 48V/28A [at least] when held between ~3500>4500rpm through variable gearing.

 

[John in CR]

That's the rotor, so where's the stator? Isn't that what matters and that rotor construction is just to save on magnets?

 

[Miles]

That's the rotor, so where's the stator? Isn't that what matters and that rotor construction is just to save on magnets?

Follow the link, John. Everything matters... It's the opposite, that rotor construction requires more magnet material.