Awe. Well too bad. Would rather send my money your way.
2 Likes
I’ve got an application that could use that.
36 kW brushless motor for an aircraft. It came with a Sevcon but I hear they are a bitch to program.
3 Likes
Yeah SEVCON is notorious for that. I’d like to challenge them one day with that higher powered controller I spoke of. Gotta get these smaller ones mastered and done first though.
3 Likes
If you ever go that route let me know.
This is a repurposed electric motorcycle engine and it is a long term project.
2 Likes
You have to be proud of you! Really impressing achievement
5 Likes
Congratulations 
4 Likes
Looks like you’re meassuring the ringing on the rising edge?
Can’t really tell where Y1 is but delta seems to be 7.2V. (guessing Y1 is the flat part after the ringing)
So a 7.2V ringing of maybe 100ns on 20S ?
Hard to tell how long one peroid is but your DIV looks like 500ns? Frequency is definatly in the kHz area but can’t say more than that 
4 Likes
Ah we have someone who made an attempt! Not bad btw @linsus .
This is a scope shot of the low-side MOSFET turnoff with the Vds (green) and Vgs (purple) waveforms. Battery voltage is 88.8V(Y1 cursor) and the spike goes up to Y2 (96V). So only a 7.2V spike with a 88.8V voltage supply at 50A FOC(this is a bit above the maximum operating voltage for users. Don’t try this!)
MOSFET turnoff is generally when voltage spikes happen. It is directly proportional to how much current is flowing (motor current) and how fast it is being turned off. If you slam MOSFETs on and off, then you increase the magnitude of the spike. Turning them on and off a wee bit slower reduces this spike and therefore risks of problems. The tradoff of turning on/off the MOSFETs slower is increased switching losses which leads to a bit more heating. I think I’ve found a decent balance though since this controller is only mean’t for less than 50kHz switching frequency at the moment.
14 Likes
No idea what it is, but everyone else liked it and it appears to be a good thing.
11 Likes
In summary, the Little FOCer seems to be ok running 50A FOC at 88V on the bench. I’m still advertising to not run above 20S (84V) though.
15 Likes
Haha, if you had a picture of where the probes where, I’d be able to make a more specific assumption xD
3 Likes
Thanks for that, and congrats!
3 Likes
Fair enough!
I wish other hardware developers would post these kind of waveforms somewhere…
4 Likes
Looking forward to see them pretties running in builds! GG!
2 Likes
Most stuff I probe has an NDA attatched to it
…man that sound dirty af.
6 Likes
Rigged up my ebike for 72V and threw in the Little FOCer. 60A FOC and started at around 82V. 37mph on a bike is a bit scary at first but super fun! I bet I can top this out at 40mph on a proper straight road
20 Likes
I approve of your wiring job.
+8 fossy qc points
7 Likes