Serious FOCer (84V VESC 6 based controller)

Electric Motors and Controllers
Feist92   10 mW

10 mW
Posts: 31
Joined: Sep 12 2017 5:27pm

Re: Serious FOCer (84V VESC 6 based controller)

Post by Feist92 » Jan 10 2020 11:48pm

Thats a real shame but no need to apologize at all. Im sure everyone here appreciates the amount of work and difficulty of what you're doing, Its well and truly over my head.
Just as a test would it be possible to orient the boards further away or 90 degrees to each other to get the logic board away from the power stage? Could you put a third single sided pcb in between tied to ground?
But dont listen to me, I dont know what Im talking about :lol:

I think this controller will be epic once you work the kinks out so I will patiently await progress. Im really glad to hear you're not giving up on it. Keep up the awesome work :thumb:

peters   100 W

100 W
Posts: 289
Joined: Oct 20 2012 11:46pm
Location: Hungary

Re: Serious FOCer (84V VESC 6 based controller)

Post by peters » Jan 11 2020 2:34am

shaman wrote:
Jan 10 2020 12:03pm
I'm pretty sure it's due to the long gate drive traces passing from the control board to the power stage thought the pin headers.
That's very likely, I also measured that the gate and output waveforms depend on the connector position and orientation, because there is a coupled feedback from the output circuit to the gate loop. I don't even have an optimal solution for that, maybe shielded board-to-board pin connectors would be the best (if such thing exists at all). The single board design probably causes less headache.

marcos   1 kW

1 kW
Posts: 324
Joined: Nov 19 2016 11:38pm

Re: Serious FOCer (84V VESC 6 based controller)

Post by marcos » Jan 11 2020 4:31pm

Instant kills are usually caused by overvoltage or shoot through events, both can be seen in a double pulse test. Before performing any high power test your gate drive should be tuned based on your double pulse test results.

If the long gate traces are too susceptible you will have to reduce the gate drive current to slow down the switching. Miller self turn-ON and overshoots are the most likely mosfet killers. Not sure what would kill a DRV, could be a voltage spike coming into a gate drive pin, which could be clamped with an external pair of schottkys to 12v and gnd.

Low side current sense produces higher EMI due to larger current loops and that one is hard to deal with.
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shaman   1 kW

1 kW
Posts: 301
Joined: Dec 10 2018 7:03pm
Location: Fort Worth, TX, USA

Re: Serious FOCer (84V VESC 6 based controller)

Post by shaman » Jan 13 2020 11:53am

@marcos I'll try reducing the gate drive strength and see if that helps. I'll still poke and prod the 2-board design to see what's going on for my own learning. I should have put the gate driver on the power stage board and only passed the digital signals between them.

@nieles Yeah EMC is a special kind of voodoo that can get complicated. It just so happens to be a hot topic in my department in my full time job and I've been diving into it. Yeah loop size or "area in the between the traces" is definitely a major factor in EMC immunity and emissions. @marcos really helped me in how to identify them.

@peters Yeah all in all I think switching to a single board with ideal driver placement, short gate drive traces, and a proper drive strength setting will all come together for a more solid design. I'm almost done designing the 5kW version. Look for a render sometime this week.

shaman   1 kW

1 kW
Posts: 301
Joined: Dec 10 2018 7:03pm
Location: Fort Worth, TX, USA

Re: Serious FOCer (84V VESC 6 based controller)

Post by shaman » Jan 13 2020 11:54am

Feist92 wrote:
Jan 10 2020 11:48pm
I think this controller will be epic once you work the kinks out so I will patiently await progress. Im really glad to hear you're not giving up on it. Keep up the awesome work :thumb:
Thanks for the encouragement! I'll crank something out. It's just a matter of time!

oleon   1 µW

1 µW
Posts: 3
Joined: Jan 18 2020 5:30pm

Re: Serious FOCer (84V VESC 6 based controller)

Post by oleon » Jan 23 2020 3:36pm

Hello, Shaman.

Looking for controller information yesterday, I found the Serious FOCer thread.

I am building a "Kart-enstein", an AWD buggy using 4 hub 60V 10000W motors of the kind used in the city coco scooters.

I already have the wheels (engines) and part of the chassis, but I'm still looking for the controllers.

The possibility of driving two of the motors with only one controller seems excellent to me. The maximum consumption of these motors should be about 18-20A @ 60V.

If you think your controllers can be used in my project I would like to contribute what I can and buy a couple of units when they are available.

Thank you

shaman   1 kW

1 kW
Posts: 301
Joined: Dec 10 2018 7:03pm
Location: Fort Worth, TX, USA

Re: Serious FOCer (84V VESC 6 based controller)

Post by shaman » Jan 24 2020 9:03am

@olean

To clarify, there is still one controller per motor. The controllers can connect via the CAN bus to work together to drive a dual-motor system. 18-20A @ 60V per motor should be fine for the 5kW controller. Stay tuned for updates here and for when I have hardware available.

shaman   1 kW

1 kW
Posts: 301
Joined: Dec 10 2018 7:03pm
Location: Fort Worth, TX, USA

Re: Serious FOCer (84V VESC 6 based controller)

Post by shaman » Jan 25 2020 1:06pm

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Angled

Working on this for the 5kW version. Looking to have the layout reviewed before prototyping. I may ditch the DRV8353 for the 10kW version and switch to half-bridge drivers. 10kW may be just too much energy for that little DRV IC.

Feist92   10 mW

10 mW
Posts: 31
Joined: Sep 12 2017 5:27pm

Re: Serious FOCer (84V VESC 6 based controller)

Post by Feist92 » Jan 31 2020 5:41pm

Looks good to my uneducated eyes. I'll buy one :D

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