big motor small controller

Hello, I am wondering if its possible to run a motor like the 15070 27KV from alienpower with Lebowskis new power stage.
Im guessing that optimally youd want something like a size4 Sevcon.


Either way would it be a good idea to go this path for either one of these reasons ?
-Benefit from low Kv winding.
-Test setup and upgrade down the path

edit: im thinking of brushless controllers and motors with a big gap in power range
Thank you, Cheapcookie

For maximum power, the controller and motor should be rated about the same. If your motor is rated too low, you'll likely fry it. If your ESC is rated too low, you won't have any power and may fry it too.

27kv is pretty high for an eBike motor. You'll want a decent controller. I'd recommend a 50 amp, 36 volt controller based on the thumbnail image in your post.

it might not be obvious but the motor referenced above is capable of 10s of kilowatts

As a heads up, if you do decide to go the big-terrifying-outrunner route, all of the Alien Power Systems and Epowerhobby stuff is just made by FRCHobby in China. They have an Alibaba store, so you can just get what you want directly from them.

I don't have an actual answer as far as if an opensource controller will run it well, and most of what I know involves the 120mm outrunners, but your biggest concern for controller selection is going to be erpm (because of the hilariously high pole count) and current levels.

For the 120100's that I have (I'm going to run two of them in a motorcycle), they're 50kV motors with 28 poles rated at 25kW each, and I would need 70,000erpm in order to get 5,000 rpm out of the motor. My controllers are pretty small (Kelly KLS7230S's, 120A cont/300A max), and in a few days once my usb-serial converter shows up I'll have a lot more info for you about how well the controllers can run one of these. Since my pack comes off the charger at 84 volts, we're looking at a maximum of 4200rpm, which will still be more than enough for highway speeds with good acceleration, if the controllers play nice.

With a 27kV motor, you probably aren't going to be looking to spin it higher than 2500rpm (~92 volts) anyways, so you'd be pretty okay with a ~40,000erpm controller like one of the big APT's I linked below even if it has 32 poles. With up to 600A of phase current, you could probably move a motorcycle pretty well with one of these.

http://www.cnqsmotor.com/en/article...V 96V 8kW PM Motor Driver Controller/332.html

I'm just about done sourcing parts for my build, and I kind of wish I'd gone higher voltage rather than high current 20s, though. Running a bunch of 1/0 wire is going to be a bit of a pain.

very interesting
I am also concerned of reducing the speed mechanically
vesc 6 is capable of 100000+ erpm

If you've got 100,000 erpm to play with, then don't really worry about the number of poles I guess.

You'd obviously want/need a pretty beefy power stage to run this guy, and if you really go with that low of a kv, a decent chunk of voltage as well.

For an idea of what kind of gear reduction you're looking at, my bike will be spinning the motors to ~4000rpm, and has a 4:1 gear ratio into a ~24in rear tire. This should be good to around 75mph, with around 280lbs of torque at the rear wheel (which means forward thrust is around there as well because of the ~1 ft radius on the tire) if I feed 300A into each 50kV motor.

For the motor you're looking at, the torque constant should be roughly double what I'm working with (around .27lb-ft/A I think?), and depending on which 150mm outrunner you're looking at you can throw 3-400A at it. At 300A you're theoretically working with around 80lb-ft of torque, and a bit under 110 at 400A.

At this point, your final drive ratio is just a matter of balancing how fast you'd like to top out vs how much torque you'd like at the wheel. Compared to my setup, you're looking at roughly half the RPM but double the torque at a given rpm/current.