AIRCOOLED BRUSHLESS DC MOTOR

LOWRACER · Mar 28, 2010

Nearly everyone knows coil smell, to avoid that, an electric motor must be good cooled!
The problem is the staying heat into the motor.
Another problem is that the heat in coils change the resistance (ascending) and you will lost a lot of power.
In the following videos I've created a little biturbo blower for my Lowracer Hybrid speedbike.
The blower has only the size 40x40mm, a length of 60mm and it turns up to 25000rpm!
Don't underestimate the power of small things, it's stormy!!!

At 1st, I've prepaired the motor...
[youtube]4uf2TcosiMU[/youtube]

At 2nd, I've decided me for this little blower...
[youtube]Kvm7v6TMykU[/youtube]

At 3rd, I've tested the run again, voltage, amps, speed, heat and torque
[youtube]gTNrTnEXudY[/youtube]

gogo · Mar 28, 2010

Very nice forced air solution. It would be very interesting to know how much it increases the power handling ability of the hubmotor. Along with the MOSFET cooler, you have addressed two of the weakest links of increased hubmotor performance. Now you will have to worry about spinning the stator on the axle pressfit.

Doctorbass · Mar 28, 2010

Hey LOWRACER, we talked alot about you and your setup here on the E-S forum!

Welcome! !! Your work is certainly inspirating ebikes fans!

I think you did, and built exactly what we always wanted to do but none of us did that from now.. and you accomplished that forced aircooled hub motor!

I love the way you present your build in your video, Very nice work!

Some of is thought about liquid cooled hub motor using copper tube inside the hub, on the stator and many desing was discussed, but we never tried that.

I personally would very appreciate if you cold give us some data about the performances of the hub when cooled or not.

I mean for the same battery voltage, what is the acceleration difference when cooled... maybe using the cycle analyst etc...

I noticed that when my X5 hub motor stator reach above 125 celsius, the acceleration is attenuated and it is less efficient due to the resistance of the winding that is higher.

So if you could help us to determine the % of performance increase with different temperature of the hub motor we would really appreciate!

Did you installed a thermobeter probe on the stator? ( ex BBW didital thermometer) ?

Doc

BiGH · Mar 29, 2010

Hey Lowracer,
Welcome and what is the make / model of those blowers?

Thanks,
Haydon

LOWRACER · Mar 29, 2010

@ BiGH

It's normaly for an industrial application. I think, it's not easy to find.
BUT, you can use all RADIAL BLOWERs, you got these in a computer shop.
The radial blower produces more pressure than a axial blower.
Then it's easier to handle, there isn't a slope of the air flow(stall).
Additional you can make an air filter on the air intake, so it keeps your motor clean.
Remember also, that the stator(coils) has got only 1mm space to the rotor(magnetics)!!!
Without an air filter it can happen, that a little grain of sand destroy a hallsensor or a coil,
of course that's the death of all motor!
For the air outlet you need normaly nothing, the forced air disable that the dust or dirt coming inside.

Here an example of a 12Volts 120mmX120mm radial blower
View attachment 12V.RadialBlower.JPG

LOWRACER · Mar 29, 2010

@gogo

I've tested the normaly 36V/500W hubmotor in a "burn out" with about 1500Watts.
The battery voltage in the operation was 38.6Volts, the limited current was exactly 40Amps.
The controller with the tunnel heatsink has got 46Celsius, the motor only 32Celsius.
Ambient temperature was 11Celsius.
After 8min the tire was blown... Test finished!

LOWRACER · Mar 29, 2010

BiGH · Mar 29, 2010

LOWRACER said:
@ BiGH

It's normaly for an industrial application. I think, it's not easy to find.
For the air outlet you need normaly nothing, the forced air disable that the dust or dirt coming inside.

Here an example of a 12Volts 120mmX120mm radial blower

Thanks for the idea

The circular heatsink - are you intending on putting a blower or two on that too?

vanilla ice · Mar 29, 2010

Nice job! I have one of those radial blowers. Still haven't stuck it on anything tho.

grindz145 · Mar 29, 2010

hey Lowrider, that thing is so badass! The cooling solution is so well done. I think there is alot more to be said for active cooling in order to get lighter, more efficient motors with more power output.

I can only imagine the looks you get going down the road in this batmobile!

love it! :mrgreen:

BiGH · Mar 29, 2010

another question for you - how are you attaching your Caps to eachother and to the heatsink?

Active cooling = AWESOME

edit: http://media.digikey.com/pdf/Data Sheets/Delta PDFs/GFB40x40x56mm.pdf Looks quite promising

for the motor

and
Heatsink tunnel: http://shop.voltelectronics.com.au/...4_d_HH8530&utm_source=getprice&utm_medium=cpc

with one of these at each end:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=603-1172-ND

I would suggest would keep the heatsink pretty chilly

LOWRACER · Mar 30, 2010

BiGH said:
another question for you - how are you attaching your Caps to eachother and to the heatsink?
Attach the caps separate from the heatsink. Remember that the caps are "bootstrap"- or "charge pump"-caps and with a permanent load they are getting f**king hot!!! In the most cheap china controllers you'll find caps with 63V/1000uF/85Celsius. In a better controller you'll find caps with 100V/1000uF/105Celsius. Maybe you decide now, "OK I don't need the caps...", that doesn't work!! In this case the FETs doesn't operate correctly!

Active cooling = AWESOME

edit: http://media.digikey.com/pdf/Data Sheets/Delta PDFs/GFB40x40x56mm.pdf Looks quite promising for the motor

That's the same type & brand like my blower...
It works in 2 steps, so it gets more pressure in the air flow.
and
Heatsink tunnel: http://shop.voltelectronics.com.au/...4_d_HH8530&utm_source=getprice&utm_medium=cpc
This tunnel heatsink is OK, but don't forget the insulating for the FETs(screw), the insulating foil behind the FETs and ALWAYS take thermal heatsink paste under the foil and under the FETs. If you forget the insulating the middle pin of the FETs is short-circuited and under power is burn down in seconds!
On one side you mount the FETs and on the other side you can mount voltage regulators(example for the light,fan)
with one of these at each end:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=603-1172-ND
Well, you need only one to the air intake. For the intake&outlet you can make a grid.
I would suggest would keep the heatsink pretty chilly

LOWRACER · Mar 30, 2010

Doctorbass said:
Hey LOWRACER, we talked alot about you and your setup here on the E-S forum!
Well, I don't know it, a friend(Pablo) mail to me and send me a link of E-S...
Welcome! !! Your work is certainly inspirating ebikes fans!

I think you did, and built exactly what we always wanted to do but none of us did that from now.. and you accomplished that forced aircooled hub motor!
It was just an idea, not difficult but it works!
I love the way you present your build in your video, Very nice work!
Thanks!
Some of is thought about liquid cooled hub motor using copper tube inside the hub, on the stator and many desing was discussed, but we never tried that.
That was my idea too, but there's no place for a tubing, also you will need a little liquid pump, a cooler and for cold seasons a anti freeze...
I personally would very appreciate if you cold give us some data about the performances of the hub when cooled or not.
Take a look, I have posted it @gogo.
I mean for the same battery voltage, what is the acceleration difference when cooled... maybe using the cycle analyst etc...

I noticed that when my X5 hub motor stator reach above 125 celsius, the acceleration is attenuated and it is less efficient due to the resistance of the winding that is higher.
Normaly not more than 90Celcius, that's the point of coil smell and the sneaky death of all motor!
So if you could help us to determine the % of performance increase with different temperature of the hub motor we would really appreciate!
So nobody has got 100%efficiency, that impossilbe! BUT I'm sure that 93%-95% with a cold motor AND a cooled motor are feasible!
Did you installed a thermobeter probe on the stator? ( ex BBW didital thermometer) ?
In an operative test, I've tested everything with a infra-red thermometer pistol. So I can test turning parts(motor) or parts they are not to be touched in a test run(IC's,Microprocessors,MosFETS)
Another advantage, it's super exact and I can "scan" the heat!

Doc

LowRacer

AIRCOOLED BRUSHLESS DC MOTOR

LOWRACER

100 W

gogo

1 MW

Doctorbass

100 GW

BiGH

100 kW

LOWRACER

100 W

LOWRACER

100 W

LOWRACER

100 W

BiGH

100 kW

vanilla ice

1 MW

grindz145

1 MW

BiGH

100 kW

LOWRACER

100 W

LOWRACER

100 W

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