# Hub motor selection help!



## dcb (Dec 5, 2009)

Arent the suppliers kinda restricted in formula E?

Also, isn't handling a concern? What is wrong with axle shafts to keep unsprung weight and gyroscopic forces and decentralized mass at bay?

Hub motors appear to be working for the Grimsel even when not going in a straight line, but I expect that there is a better way.


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## Hollie Maea (Dec 9, 2009)

boilerup_PER said:


> Any suggestions?


Sure! Don't use hub motors. You can still have 4 motors, AWD, etc.


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## boilerup_PER (Apr 13, 2015)

I realize the con of hub motor, but there s no room in the front of the car for axles and motors. Also, the car is traction limited. Based on calculation, hub motor would improve lap-time by a lot ?


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## dcb (Dec 5, 2009)

kinda depends on the track don't you think? Certainly you have more regen available up front, but accel will be rear biased.


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## boilerup_PER (Apr 13, 2015)

Yes, it depends on the track. The main thing I need help with is generating a motors pool for selection. We are generating one right now. However, we might miss a few. So if you know any motor that fit the requirement above,please leave a comment below.


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## dcb (Dec 5, 2009)

well I am perhaps mistaking "Perdue E formula" with formula E, the rules there keep changing, the only manufacturer there that looks possibly US is Andretti.

So you are looking for 120kw total? Do you have a link to the rules/regs for this competition for the curious?


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## boilerup_PER (Apr 13, 2015)

Thank you for helping
Yes, 120 kw total. Maximum power draw is 80 kw,so there s no point of having too much. 
here is a link to rule for 2015-2016
http://students.sae.org/cds/formulaseries/rules/2015-16_fsae_rules.pdf


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## Tomdb (Jan 28, 2013)

All the European teams running four hub motors got theirs custom made/adapted to suit their purposes.

I would suggest contacting a manufactures of servo drives or other automation motors with the question if they are willing to help you out. You will also need a large reduction set per wheel in order to run wheel motors that are very compact and lightweight.


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## Karter2 (Nov 17, 2011)

boilerup_PER said:


> Also, the car is traction limited. Based on calculation, hub motor would improve lap-time by a lot ?


 You must have a very limited wheel/tyre choice if you are traction limited at 120 kW ?


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## Tomdb (Jan 28, 2013)

Karter2 said:


> You must have a very limited wheel/tyre choice if you are traction limited at 120 kW ?


Guys please get your facts right, this topic is about a FSAE car. 

So the total setup including driver is sub 400kg (when done alright). Sub 300kg when done excellent.

So traction limit will be very present.


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## dcb (Dec 5, 2009)

was looking at SRM's again, noticed that this is a north american company

Nidec Motor Corp 22kw to 250kw... *maybe* they would be useful, do your homework before talking to em of course.

http://powerelectronics.com/content/case-switched-reluctance-motors

One other thought, generally larger motors are more efficient, so there *might* be another case for a differential(s) and a larger motor, though gears add losses, but unless you have a very large rotor, you will be using gears anyway.

Also, there are plenty of places that can laser cut stator/rotor laminations.

edit 2: http://motorsolver.com/ might be a good start

edit3: SRM might not be a good fit for in-wheel motors though: http://www.greencarcongress.com/2015/01/20150127-srm.html


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