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Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 04 2015 3:05am

Hi all, just a question from a lurker with a mass produced eboard and dreams to DIY: Is there any noticeable drag when the motors are offline?

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Vanarian   10 kW

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Re: community project HUB MOTOR

Post by Vanarian » May 04 2015 11:56am

The two noticeable drags are from magnets / stator meeting each other and also the weight of the motor.

If your motor is also on good lubricated bearings you should not meet much drag when offline :)
-+AT-One project : electric inline skates - no remote, hub motors, one frame for various wheel sizes & quasi-universal boot mount

Rollo Ergo Sum!

Hummina Shadeeba   1 MW

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Re: community project HUB MOTOR

Post by Hummina Shadeeba » May 04 2015 1:11pm

a "slotless motor" would have no cogging

found this:
Despite the many advantages BLDC motors, they possess a limiting factor: the tendency to exhibit torque pulsations.9 These pulsations can cause acoustical noise and vibration, and can “severely limit the performance of the system, specifically in high precision and high stabilization applications.”10 In high speed applications, torque pulsations can be filtered out by the inertia of the load. However, at low speeds, when they are most noticeable, torque pulsations can greatly limit performance.11 Torque ripple is caused by both the BLDC motor and PWM drive controller design and include “geometric imperfections in the motor, imprecise commutation, fidelity of current driving waveforms, phase delays, friction, and the magnetic hysteresis in the motors. They may be reduced through better motor design or the use of better drive controllers.”12

Torque ripple is divided into two general categories: cogging torque and commutation torque. “Cogging torque is produced by reluctance variation due to the stator slot openings as the rotor rotates. Cogging torque can be reduced by changes in motor design such as skewing of the stator slots, choosing a fractional slots/pole motor design, or choosing a magnet width relative to the slot pitch.”13 Commutation torque ripple is caused by the drive’s PWM inverter and is due to electrical current hysteresis or the inverter generating high frequency current ripple. During commutation, “as one phase turns off, another turns on, [so] the rise and fall rates of the respective phase currents are not equivalent and thus the torque generated by the two currents during commutation does not instantaneously add to the value of torque of one fully excited phase, which would allow a smooth torque over the commutation interval.”14

To minimize commutation torque ripple, improvements in BLDC drives are required. There are several methods used in motor drive designs to minimize commutation torque ripple. One way is by adding inductor-capacitor (L-C) filters to “reduce the high frequency component of the inverter’s output to the motor. 15 But a key factor in reducing torque ripple is eliminating torque harmonics by “adjusting the conducting phase of the windings so they compensate appropriately.”16 There are four other methods being introduced to achieve torque ripple reductions: (1) using direct torque control, (2) dynamically changing the input voltage, (3) adding torque estimation circuitry, and (4) employing artificial neural networks and active disturbance rejection control.17
Last edited by Hummina Shadeeba on May 05 2015 9:52am, edited 17 times in total.

Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 04 2015 4:48pm

Thanks! "cogging"... That was the word I was looking for. Back to observer mode... So much to learn!

torqueboards   100 MW

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Re: community project HUB MOTOR

Post by torqueboards » May 05 2015 3:21am

Szogs wrote:Hi all, just a question from a lurker with a mass produced eboard and dreams to DIY: Is there any noticeable drag when the motors are offline?
Once you go electric, why would you bother kicking? I never kick push anymore.

Too much fun riding with no effort. :mrgreen:
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Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 05 2015 3:46am

I don't know really. I call it the Kindle effect: I'm totally sold on e-readers, but some part of me yearns for old school feels which adds no practical value to the text. On the other hand:

Electric one-line from this morning in the park at the top of a hill, where a group of runners are standing around gasping and wiping their brows. They stare at me as I carve uphill, tranquil, in my business suit. "Sweaty work, huh?"

All laugh, and half of them point and say "Ooh electric!"

Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 14 2015 12:06pm

Holy cow. Ask and you shall receive. Check out the Mellow drive kickstarter! Mountable drive system with dual hub motors and swappable battery!!!

“None of the existing rides on the market could satisfy all our expectations. That’s why we designed Mellow. It’s a flexible system that easily adapts to your individual needs. It’s mountable, which means you can choose any board you like and transform it into your Electric Mellow Board. Mellow also comes with a swappable battery, giving you the freedom to ride for as long as you like.

What we love about surfing and snowboarding is the effortless floating feeling of the ride. We wanted to make sure that Mellow gave us the same feeling, so minimum weight and maximum latitude was vital, when we started prototyping. The two in-wheel motors deliver direct transmission and a performance that will let you carve powerfully, fly up hills and put a big smile on your face.

The Mellow Drive is the first ever drive system for skateboards that can be mounted under pretty much any deck. Just pick your favorite and turn it into a full on riding machine.”

torqueboards   100 MW

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Re: community project HUB MOTOR

Post by torqueboards » May 14 2015 12:10pm

5mm Thane is SICK man!@ :mrgreen:

Buy replacement wheels after 1 ride :) lol jk
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psychotiller   10 kW

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Re: community project HUB MOTOR

Post by psychotiller » May 14 2015 12:33pm

torqueboards wrote:5mm Thane is SICK man!@ :mrgreen:

Buy replacement wheels after 1 ride :) lol jk
lol jk...but not really
www.psychotiller.com

builds:
XT Wheels/Custom Hub & mount on Randal 180's/Drop Throughhttp://endless-sphere.com/forums/viewto ... 35&t=59259
6" Pneumatic Tire Drop Down/Drop Through http://endless-sphere.com/forums/viewto ... 35&t=60449
"Have you ever heard of Plato? Aristotle? Socrates? Morons!"-Vizzini

Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 14 2015 1:04pm

That would explain the "easily exchangeable" description. Haha

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LEVer   10 kW

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Re: community project HUB MOTOR

Post by LEVer » May 14 2015 1:25pm

Szogs wrote:...Is there any noticeable drag when the motors are offline?
Almost none when you go hubmotors, even online. You actually wanna put drag brakes cause you're worried you're not gonna stop in time.

Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 14 2015 1:43pm

The Mellow Drive specs state:

Peak System Power: 2300
Torque: 3 Nm (1.5 Nm per motor)
Maximum Grade: 20%

Does the stated torque fit with what you would expect from a hub motor? Does the 20% grade seem like a realistic figure?

Szogs   1 W

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Re: community project HUB MOTOR

Post by Szogs » May 20 2015 5:42am

Hey Torqueboards, the Mellow is essentially a tricked out truck...so you can just stick a second one on to get the 4wd you want. One of the co-founders just said he'd done this and will be testing it out soon (check out the comments on the Kick-start).

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bandaro   10 kW

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Re: community project HUB MOTOR

Post by bandaro » May 20 2015 6:54am

So where are we at with this? My composite deck is basically finished and ready for testing, so looking at a new project for this. Has anyone other than pedi done the conversion? Or any schematics/diagrams of intentions drawn, or should I do some?

Hummina Shadeeba   1 MW

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Re: community project HUB MOTOR

Post by Hummina Shadeeba » May 20 2015 2:31pm

i know ive said it before and I'm constantly surprised how long it's taking but addictedtoclimbing and i have changed the design many times. We'd planned to design it ourselves and then make four of them and THEN post up here to see what the interest was and then do a bulk order to make it cheap and all in AT COST. At that point we could make it more communally controlled but for the inital design we want to do it ourselves because too many cooks....

The design is alllmost done. Addicted is really busy and we've been back and forth changing many times based on convenience of use and durability and easy of manufacture but i think we're coming to a conclusion realy soon and within a day or two I'll post screen shots or a link to the edrawings

Initially we'd planned on puttng the stators from tacon 160s in as well as the magnets but for safety sake we're going to go with a motor manufacturer and get them to do it all. the plan is to optimize with a hallbach array and some motor manufacturers say they with do that. typically outrunners lose a lot of flux which can be seen with just a paperclip test and this will really help the torque. Getting the torque from just one motor should be doable and we're trying to do that...keep costs done and simplify the build

Give me a day or two to get something up and then tell me what you think and we can go from there.

One question is the material choice for the rotor. Mild mild steel is best for flux redirection (the hallbach will help A LOT on this) but still we'd prefer a mild steel that's strong enough, mild enough, and wont rust. Maybe a finish on the metal?

the rubber I've got someone who's cast wheels himself helping ...as soon as we have the final design of the rotor done! We keep switching as I say. The latest change has been to have the rubber easily removed without having to take off the motor.
blah blah.. give me two days and I'll give you something real we can talk about.

We've just finally gotten the threading for the surfrodz and plan to use it's pin to secure the motor and that was a big hold up. which is ridiculous.

addicted2climbing   100 W

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Re: community project HUB MOTOR

Post by addicted2climbing » May 21 2015 1:08pm

Hey Guys,

As Hummina said, I have been a it of the hold up. Well myself and the truck manufacturer not getting me the info I need to finalize the design. I received the CAD files from the truck manufacturer yesterday and was able to finalize the last pieces of missing information. I was up until 2am last night and the design is done. I forwarded it to Hummina to have a look and see what he thinks. As of now just the 3D cad is done and once we approve there are no more changes I need an evening to detail the drawings for the machine shop. So I know Hummina has said it many times, but we are very close.

In regards to materials, I am more use to working with aluminum and stainless so my knowledge of mild steels suitable for the motor can is a bit low. For the Stator shaft, I was thinking a good strong stainless like PH17-4 or 416 Stainless. I am open to suggestions for the motor can.

Marc

Hummina Shadeeba   1 MW

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Re: community project HUB MOTOR

Post by Hummina Shadeeba » May 21 2015 2:22pm

looks great to me!

only one ring to hold the motor together... and the rubber is easily removed without taking the motor apart.

Marc says he'll finish up the 2d drawings in a day or two at most and then I can get quotes from a couple motor places that are waiting in a day or two beyond that.

these can be hard to visualize

:one big bearing on the inside, one small bearing with flange on the outside, a ring that's threaded,...otherwise it's just a rotor and stator that have bearing seats cut into them....and the last part is the flange to hold the wheel on
Attachments
Hub Motor 2.jpg
Hub Motor 2.jpg (61.38 KiB) Viewed 809 times
Last edited by Hummina Shadeeba on May 30 2015 12:43am, edited 3 times in total.

Freshair   100 W

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Re: community project HUB MOTOR

Post by Freshair » May 21 2015 2:41pm

Looking good!
Low impact to no impact

jetpilot   10 µW

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Re: community project HUB MOTOR

Post by jetpilot » May 21 2015 6:49pm

looks great :twisted:

Kronos   1 µW

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Re: community project HUB MOTOR

Post by Kronos » May 22 2015 1:05pm

New guy here. Definitely interested in this.

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okp   100 kW

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Re: community project HUB MOTOR

Post by okp » May 22 2015 1:21pm

awesome!

jacobbloy   100 W

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Re: community project HUB MOTOR

Post by jacobbloy » May 25 2015 3:04am

Looks good guys!

Can't wait until you get some made up!
It's interesting how there are many ways to do this and why it isnt done more often.
image.jpg
longboard hub motor 51mm stator
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longboard hub motor 41mm stator arc magnets and rotor
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longboard hub motor 41mm stator arc magnets and rotor
image.jpg (104.12 KiB) Viewed 2071 times
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63mm hub motor 2pcs shaft for any longboard skate board axel
image.jpg (69.04 KiB) Viewed 2071 times
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63mm hub motor 2pcs shaft for any longboard skate board axel
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63mm and 53mm longboard hub motor rotor's
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63mm longboard hub motor caps
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Assembled longboard skate board hub motor 63mm and 53mm
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These are some of my updates. Hope you all like!
I'm looking to make a 150mm wheel with a 8085 motor stator inside.
Should be sweet.

Hummina Shadeeba   1 MW

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Re: community project HUB MOTOR

Post by Hummina Shadeeba » May 25 2015 1:30pm

We changed the design again. This JPEG is missing the outer flange that will bolt on so the rubber can be removed without taking the motor apart. This is the final design! Please tell us what u think

Those are interesting Jacob but isn't that the same design as before? From what I remember of your last iteration, which looks exactly the same, they didn't go due to tolerance issues. I assume you will get the tolerances good enough this time and hopefully the people who bought your stuff before will get something that works from you.

But let's compare the designs:
There are double the interfaces in your design: double the risk of movement and double the possibility of having slop. Your design had/has no secure way to mount the motor that anyone could consider safe. It also effectively has an aluminum axle that must support weight. Smaller bearings. Have to take the motor apart to change rubber. The mounting bolts on yours strip really easily, I stripped them, they're small and many. What other differences?
Attachments
image.jpg
image.jpg (107.02 KiB) Viewed 623 times

2wayspeaker   10 mW

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Re: community project HUB MOTOR

Post by 2wayspeaker » May 25 2015 2:34pm

I don't get something.
How is the "stator" (that actually moves) held together on the assembly under lateral force except by a very tolerant fitting?
This seems grossly insufficient?
Or perhaps I interpreted it wrong: Here's what I think I'm looking at.
Image

I also do not like the fact that you need a completely custom truck. I'd be a way better design starategy to make it fit current trucks.

Hummina Shadeeba   1 MW

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Re: community project HUB MOTOR

Post by Hummina Shadeeba » May 25 2015 3:40pm

Having it fit only the surfrodz is annoying I agree but they have gotten pretty cheap and this way the motor can be secured more safely and removable; otherwise what option is there to secure the motor? Glue? Jacob's 3m bolt is totally inadequate and I've yet to see anyone say otherwise.

The labeling of the parts you did isn't right. What you write is rotor is stator and vise versa.

In your second drawing there is nothing supporting the bearing on the other side, as you say, but the design will use the threaded ring that sits on the inside edge

But thanks for your thoughts and please ask if things aren't clear or you think maybe there's some other obstacle. I'd like feedback of any sort

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