75 KW Axial Flux Motor Design Help

Electric Motors and Controllers
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ardillo lambo   1 mW

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75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 23 2020 9:41am

Folks,

I'm planning converting a sports motorcycle (2004 Yamaha R1). As part of the project, would like to design and build my own motor. After some research, would like to go with a YASA type motor. Not too much information available out there on how to calculate some of the electrical characteristics. I already did the mechanical design in solid works for the stator, rotor disks and shaft, just as a starting point. some of the dimensions are based on documents found during the research. Those dimensions can be modified as needed to satisfy the performance criteria below:

75 kW continuous power
150 kW peak power(1 min)
80 N.m continuous torque
160 N.m peak torque (1 min)
6,500-7,000 RPM
470 nominal DC voltage (for controller)
3 phase
18 magnet poles
20 coils

I was wondering if any of you guys can point me in the right direction on how to calculate/determine some of the electrical characteristics.

will be posting some screen shots for the mechanical design in a few days.

Regards,

major   10 kW

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Re: 75 KW Axial Flux Motor Design Help

Post by major » Feb 23 2020 11:23am

Hi ardillo,
Very ambitious of you. Too much so, IMO. Suggestion is to start small, say, 0.75 kW. All design characteristic principles are the same. Just scale will save money in long run.
Review APL's build thread if you haven't done so.
viewtopic.php?f=30&t=97860
Regards,
major

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 23 2020 2:31pm

Major,

Thanks for the advice. Big or small, still need the electrical equations thou....let me check APL's build.

Regards,

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amberwolf   100 GW

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Re: 75 KW Axial Flux Motor Design Help

Post by amberwolf » Feb 24 2020 1:38am

ardillo lambo wrote:
Feb 23 2020 9:41am
20 coils
I was wondering if any of you guys can point me in the right direction on how to calculate/determine some of the electrical characteristics.
what specific characteristics are you referring to?

(if you don't tell us, we don't know what you already know, and what you need to know).

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Lebowski   1 GW

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Re: 75 KW Axial Flux Motor Design Help

Post by Lebowski » Feb 24 2020 2:04am

you can calculate the Kv and R yourself from the magnets and amount of windings (wire length)... this will give you efficiency numbers etc.

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 24 2020 7:36am

Amberwolf,

Motor constants KV, KT, wire turns per coil, speed and torque I guess

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amberwolf   100 GW

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Re: 75 KW Axial Flux Motor Design Help

Post by amberwolf » Feb 24 2020 2:53pm

ardillo lambo wrote:
Feb 24 2020 7:36am
Motor constants KV, KT, wire turns per coil, speed and torque I guess
you've already specified the speed and torque in the first post of the thread, correct?

the kv and kt are determined from the specifications you already gave--you said how many rpm it is, and what it's max speed and max torque are, so you divide by the rpm to find out how much you need per-rpm (which is what those constants are).

i don't know (other than experimentally) how to determine how many turns you need for a new untested stator / magnet / airgap / design.

if it were an existing motor you were just rewinding, you could simply do a ratio of the original turns vs the properties it already has, vs the new properties you want it to have, to get the new number of turns.

but since you don't yet know how this particular motor design will behave, i don't know how to just calculate that. (there may be a way...i just don't know what it is. i recommend apl's ongoing axial design thread as first reading, though, as he may have the math in there--but i know he has still experimented with numbers of windings to determine rpm/etc).

Ribiero   10 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by Ribiero » Feb 24 2020 3:44pm

Check out Lebowski' s posts as well. His diy axial flux made using simple tools is inspired.

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 24 2020 5:58pm

Thanks Amberwolf....I'm looking at APL thread, lot of info there.
Ribiero...I'll check Lebosky's thread as well.

In a few days I'll posting the mechanical components for the build so you guys can check it out.

regards,

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 25 2020 10:41am

Here We go guys...

Let me know what you guys think
Attachments
YASA_Motor_1.PNG
Complete motor view without housing
YASA_Motor_1.PNG (172.82 KiB) Viewed 716 times
YASA_Motor_2.PNG
another complete view showing output shaft
YASA_Motor_2.PNG (101.94 KiB) Viewed 716 times
YASA_Motor_3.PNG
internals
YASA_Motor_3.PNG (88.1 KiB) Viewed 716 times
YASA_Motor_4.PNG
internals
YASA_Motor_4.PNG (125.49 KiB) Viewed 716 times
YASA_Motor_5.PNG
Rotor Disk, showing segmented magnets steel plate and aluminum plate. similar to APL's rotor
YASA_Motor_5.PNG (111.11 KiB) Viewed 716 times
YASA_Motor_6.PNG
side view of the rotor. Aluminum back plate is 10mm, steel plate is 3/16" thick
YASA_Motor_6.PNG (43.11 KiB) Viewed 716 times
YASA_Motor_7.PNG
rotor with bearings. output shaft is 25mm. the fat section is 62 mm
YASA_Motor_7.PNG (54.09 KiB) Viewed 716 times
YASA_Motor_8.PNG
stator hubs, with complete coil. The coils are removable and will be held in place by the dovetails and the housing as well. Stator hubs will be made out of a composite material that need to figure out
YASA_Motor_8.PNG (181.11 KiB) Viewed 716 times

coleasterling   100 W

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Re: 75 KW Axial Flux Motor Design Help

Post by coleasterling » Feb 25 2020 12:37pm

That's a lot of bearings...Way too many bearings.

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 25 2020 1:09pm

coleasterling,

I was looking only at mcmaster for the bearings, those where the ones that fit my application. I can look later for thicker bearings... But what you will suggest??? what is the correct amount of bearings for you?

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openwheel   10 µW

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Re: 75 KW Axial Flux Motor Design Help

Post by openwheel » Feb 25 2020 10:29pm

Hello

I like your thinking for the stator mounting. It looks like it could be made a lot lighter. Also there should be some means of fastening the segments in place axially.

Is this motor an inrunner or an outrunner? Maybe what cole is talking about is that it looks like there are bearings for the stator and rotor whereas typically only one will have bearings in the dual air gap axial flux topology. I see that the rotors appear to be fastened to the shaft by bolts but also mounted on bearings. I think these bearings can be removed.

Have a look at these patent drawings from YASA's Tim Woolmer. You can see that the stator is affixed to the frame and the rotors are coupled through the inner race of the bearing in order to turn an inner shaft via the splines.
Attachments
US09287755-20160315-D00004.png
US09287755-20160315-D00004.png (129.98 KiB) Viewed 669 times
ArGNuRRCMAATp_c.jpeg
ArGNuRRCMAATp_c.jpeg (41.73 KiB) Viewed 666 times
Last edited by openwheel on Feb 26 2020 10:53am, edited 1 time in total.

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 26 2020 8:02am

Thanks for the info Openwheel,

Appreciate the recommendation about making the stator lighter. I'll definitely figure out something lighter.
There are some means to hold the stator to the frame, take a look at the stator segments in the picture below, M5 threaded holes that goes all the way down to the stator hub. A set screw will serve as a pin.


The motor is an out runner....yeah!!! the bearings on the rotor side was a mental fart!!!! definitely they will be removed. Shaft will be improved as well, and yes the rotor disks are fastened to the shaft.


What material you will suggest for the stator hub???, I was thinking about a composite
Attachments
YASA_Motor_9.PNG
YASA_Motor_9.PNG (135.21 KiB) Viewed 640 times

ardillo lambo   1 mW

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Re: 75 KW Axial Flux Motor Design Help

Post by ardillo lambo » Feb 26 2020 11:03am

Her is the improved stator hub in 70## Aluminum alloy. This can be made out of a high temperature composite???
Attachments
YASA_Motor_11.PNG
YASA_Motor_11.PNG (68.89 KiB) Viewed 623 times
YASA_Motor_12.PNG
YASA_Motor_12.PNG (140.46 KiB) Viewed 623 times

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openwheel   10 µW

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Re: 75 KW Axial Flux Motor Design Help

Post by openwheel » Feb 27 2020 2:08pm

Hello,

Nice work. I'm not sure what material would be most appropriate. 7075 is paramagnetic so I think would be fine. Want to optimize for weight and strength. Do you know your weight target and volume constraints?

Aside from iteration on the interior mounting concept, it looks like the stator needs to find a way to be mounted to the motor frame on the exterior. Conceivably a mirror of a similar concept.

What manufacturing methods do you have at your disposal for prototyping?

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