Luke's commuter bicycle. What Non-hub is all about.

[geetarboy]

God! What a fun looking ride, Great work Luke!

[liveforphysics]

Two nice things about the sin/cos sensor:

• It get the position sensing element out of the stator heat flux
• It allows precise timing advance with the right controller just like a timing map in an IC ECM

Yes sir it does. We did it mainly for the heat reason you mentioned, as hall melting failure was our demise at the last race event, as well as a previous race.

The second reason you mentioned wasn't really something we were needing for this application, but WOW! It just make it silky smooth, no more chug-chug-chug at low RPM's as each hall sensor latches and tells the fets to switch the next coil on, it's just silky now, you can make the motor spin so slowly you can barely see it moving at all, and it's just perfectly smooth with no torque ripple noticed at all now. Really feels like electric power should feel at all RPM's rather than little bumps of torque pulses when you're at low speeds.

It's fun having this much torque too, I just nosed the front wheel up to a staircase outside a strip mall, and in a very slow controlled calm way, just torqued up the 10 stairs or so and rode along the sidewalk path at the top. It felt even easier than walking up stairs, though the seat does kinda smash into your ass as the rear tire goes over each step. I don't know that it would have been possible to do it so effortlessly on hall sensors.

[flathill]

Damn that is quick! Like sub 4 second 0-55mph?

Now you just need to sell the Sevcon pre programmed for this motor or give the code away to electricmotorsport and thunderstruck

Could probably get away with the smaller Sevcon gen4 and I'm guessing the same settings would work, no?

[boostjuice]

This motor fitted with external sine/cosine rotor position encoder:

http://www.goldenmotor.com/HPM-10KW%203D.jpg

Which motor wind did you select Luke? the "48V", "72V" or "120V" option?

And likewise with 'flathill', acceleration numbers would be great to know

[dirkme]

Okay, I trust you understand that this illegal and mean therefore you got to pack that ebike in a good box and send it over to me ) Now!

[amberwolf]

Pardon the lightly OT:

A bicycle worthy of my commute.

The video text says that Ryan added a sin/cos encoder...does this encoder translate into the typical 3-hall signal output, or does it just go into the controller itself as sin/cos instead? (I would bet the latter but am hoping for the former)

I'd be interested in details on it if it is the former (but I don't have a controller that uses the latter yet), as I'd like to build something like that to run that powerchair motor
viewtopic.php?p=503510#p503510
on one of my existing ebike controllers, using the existing sin/cos sensors in the motor.

What is a sine/cosine rotor position encoder?
How does it work? Can a mere mortal make one?
I like pictures

Another motor's built-in sin/cos sensor and magnet ring, also kept away from the potentially hot stator and magnets:
viewtopic.php?p=486263#p486263
The sensors themselves:


The magnetic encoder ring, mounted on the axle spindle-to-wheel-hub interface:


The output of such a sensor looks like this:

[Alan B]

Advanced motor controllers commonly have sin/cos encoder inputs. They resolve this into the precise angle of the motor rotor and drive the motor as needed. They use this to get the timing right, with dynamic timing advance, etc.

[Arlo1]

Two nice things about the sin/cos sensor:

• It get the position sensing element out of the stator heat flux
• It allows precise timing advance with the right controller just like a timing map in an IC ECM

It is so so so exciting to be in the middle of all this EV stuff just taking off! And bigmoose you deserve so much for all your help, as do many others incl luke him self! I have never been so excited for something in my life. This whole thing is the reason I can't wait to get up and go see what I can learn on my computer in the morning! 2012 is going to be a HUGE year for extreamly fast ebikes!

[liveforphysics]

Amber- It directly takes the Sine/Cosine input from the encoder. I think it's good to 0.25deg rotor position if I'm not mistaken. The halls were good to 6deg resolution (10 poles, 3 halls on 120deg spacing)

I think only Ricky's amazing DIY controller would be capable of greater than this degree of rotor position, but it sure costs a hell of a lot more in dedicated fast A2D's than it costs to mount a $50 encoder and run 4 wires.

[RWP]

I found some individual encoder chips on line.
Is it a trivial thing to mount them like we do hall's, or is this not possible?
OH...a $50 encoder...good enough!

[liveforphysics]

I found some individual encoder chips on line.
Is it a trivial thing to mount them like we do hall's, or is this not possible?
OH...a $50 encoder...good enough!

You gotta drill a pocket into the back of the motor shaft for the encoder magnet to get glued in. Then just some structure you can afix the encoder package to sit over that magnet. Then you need to clock the encoder to be aligned properly, which requires an o-scope tinkering. Then you make sure you've got which is which for sine/cosine sorted out, send that to the sevcon's encoder input, and you're ready to begin configuring the sensor to the controller and start dyno tuning.

[Kiwi]

have you got a NZ guy working with you, thought I caught a kiwi accent in the video?

Its great to see an electric bike with some power that doesn't leave you yawning.
Nice work.

[RWP]

I found some individual encoder chips on line.
Is it a trivial thing to mount them like we do hall's, or is this not possible?
OH...a $50 encoder...good enough!

You gotta drill a pocket into the back of the motor shaft for the encoder magnet to get glued in. Then just some structure you can afix the encoder package to sit over that magnet. Then you need to clock the encoder to be aligned properly, which requires an o-scope tinkering. Then you make sure you've got which is which for sine/cosine sorted out, send that to the sevcon's encoder input, and you're ready to begin configuring the sensor to the controller and start dyno tuning.

Thanks Luke - You da MAN for your manly bike!!!

OK then...is the encoder signal anything like a hall signal that would connect to a controller that is more common to what we are currently using?
Guess I am trying to find a way for a mere mortal to do this

[amberwolf]

OK then...is the encoder signal anything like a hall signal that would connect to a controller that is more common to what we are currently using?

No, not if you're talking about common ebike controllers like the Infineon/Lyen/Crystalyte/Ecrazyman/XieChang stuff; that's the problem I am asking about in my post on the previous page and in my powerchair thread.

You'd have to convert the sin/cos into the hall-per-phase types those are expecting. Can be done with either analog electronics or with an MCU and some programming, but it won't give you the resolving power of directly using the sin/cos signals, AFAIK--you're still limited to whatever the controller itself accepts for input. It does let you use encoding outside the hot motor, at least (but really, you could do that with the regular halls, too, if you add a second set of magnets just for the halls to detect. Or you could use optical sensors to do the same job the halls did, and a light/dark ring in the pattern of the magnets).

[Spacey]

Luke that bike is awesome, damn your making me want to get rid of my frock motor on my Greyborg now lol

[jingles98]

I think we've all updated our Christmas list for one of these bikes Luke. Like i said before mate, you are a God.

[gensem]

How much thrust this thing puts on the ground?
300 pounds?

[Jozzer]

[liveforphysics]

:mrgreen:

Thanks Jozz. I always value you work and input.

[Whiplash]

Hey Luke,
just a crazy question, what would you need to get to setup a drive system like this, say if one of us sent you the motor/controller and had you set it up similarly? I would LOVE to build a frame and just be able to slap a drive into it like this!!

[liveforphysics]

Hey Luke,
just a crazy question, what would you need to get to setup a drive system like this, say if one of us sent you the motor/controller and had you set it up similarly? I would LOVE to build a frame and just be able to slap a drive into it like this!!

Its just too much time. Hundreds in labor to do the machineing to mount the sine/cosine, hours of time on the scope and dyno. I couldn't do it cheaply, and the parts cost is high all ready.

[Ypedal]

I think u should have to earn this the hard way!

[Whiplash]

I think u should have to earn this the hard way!

Awe, coome oooon! LOL! I want it the easy way!


Thanks anyway Luke! I figured as much but I thought I would ask...

[liveforphysics]

I think u should have to earn this the hard way!

My ticket price to get here was around $10,000usd in parts turned to smoke. That includes ~$2,000usd in wasting my time with RC controllers alone, never having something that lasts more than a couple of minutes of my riding. Then going to bigger ebike controllers, of which, the only ones I never killed were the original hand-built Method's controllers, but my quest for power went beyond there limits. Smoked a number of motors that cost over $1,000usd each along the way, went from brushless to brushed, and then back to brushless. Went from 5lbs motors to 15lbs motors to 25lbs motors, each time finding that while the POWER could be similar, the LIFESPAN and DURABILITY just increases directly with the size of the things. I could achieve the same performance with a motor 1/5th the size, but I've all ready played that game more than anyone else, and it just ends in fickle designs that constantly break and smoke.

In the end, the simplicity and durability is just worth it to carry an extra 10-15lbs of motor around.

[gor.]

Luke, why such strange choice of motors? Agni - twice more powerful and much lighter - 11kg vs. Golden 17 kg; rpm range about the same

- to test encoder?