The NEFASTUS Axial motor (Toy Version)

[ardillo lambo]

Hi Folks,

I want to share the design process, material selection of an Axial motor as well as to get some advise from this community for the future version of this motor.
The final (man version) version is intended to be used on a motorcycle ( A Daytona 675). The toy version however is to get my feet wet and to learn some motor concepts. I would like to THANKS @APL for all the words of wisdom.
All recommendations are welcome. If someone out there have a software and know how to simulate the damn thing and want to help on that matter....let me know. Without further ado. The following specs/dimensions for the rotor and stator are based on an off the shelf wedge magnet.

wedge Magnet specs:
OD = 8"
ID = 4"
Thickness = 1/4"
Grade = N42
Magnetic Flux Density = 1.32 T

In order to keep the effective diameter of the motor under 10" I pick a 14P/12S combination. With the magnets dimensions, here is what I obtained:
I heard/read somewhere that the back iron needs to be 1/3 of the magnet thickness...can someone confirm or debunk that?
I used a 1/8" thick plain carbon steel disk as a back iron.

That's if for now....

 

[ardillo lambo]

Alright guys...here is how the rotor was constructed. I know some people will complaint about the way the rotation is transfer to the shaft via a collar with two M5 set screws, I decided to go that route because already have the bearings and shaft laying around from previous projects. The shaft design for the man's version is different.
the iron back plate (light gray) is 1/8" and the yellow mustard plate is just a 3D 10mm printed disc to provide more support.

That's it for now....

 

[APL]

Welcome to the Endless Sphere ardillo lambo, and welcome to the Motor Tech section, good to see another motor build going on. :thumb:
Good luck as you travel through the vast immensity of motor building, and looking forward to seeing how this project turns out. 8)

As far as back iron thickness goes, more is better of course,.. and as the amps rise it will be needed, such as your man version. But
not so necessary on the toy version, since it won't be used for very much power output.

It's a large amount of steel in a motor, so most people want the minimum thickness because of the weight and centrifugal rotation.
But in your motorcycle version weight won't be an issue very much, and you'll be using LARGE current, so don't hold back on back iron thickness there, as it's a major part of the magnetic circuit. As the current builds, more and more of the back iron thickness
will be needed.

One lesson I've found with axials is to overbuild first, and work on weight second.

 

[ardillo lambo]

Thanks APL
Yeah for the man version, Im planning using 10mm thick iron plates I'm playing around with FEMM changing iron back plates thickness as well with the powder iron core center bar, see how that affect the flux in the air gap. I'll share my results obtained with FEMM, see what if it make sense to go that route.

 

[ardillo lambo]

Alright!!1 her is the next update

Coil design:

Using the same approach as with the magnets


For the man version I'm planning using powder iron cores, but for the toy version the core will be a3D printed center bar (basically air core) no coil shoes. The 3D printed core will serve as a support for the copper and will help to keep the wire nice and tight.
Below the man version of coil.

For the toy version I'll be using 28 turns of AWG#14, no parallel paths. For the man version, the plan is to use square wire AWG #8, 3 parallel paths, since the controller will continuously put out 300 amps, at 100 amps per path. Forced cooling will be incorporated in the case design.
This is how the man version stator should look like

The coil pockets on the stator plates are a little bigger (.25mm around the perimeter) to allow epoxy glue to cast the coils to the stator plates.

There is plenty of room for the inter-phase wires between the out side diameter of the stator plates and the top arch of the coils. That also will be part of the cooling chamber for the man version. Fins will be added to the stator plates to force the cooling fluid in an "S" patter around the coils. The cooling fins are not shown on the previous image.

That's it for now

 

[ardillo lambo]

Here is how the motor looks assembled

The outer casing is a two part casing(not shown) that one of the halves will have a groove to put some liquid gasket. Also will have inlet and outlet ports for the coolant(ports are not shown either)
Here a side cut of the motor with all the internal parts exposed


Next posts will have pictures of the constructed toy version and parts.