I just looked to find it 
lol - I mean all things considered the DRV8301 isn’t that hard to hand solder. If everything else (sans BMI) can be done through SMT-Service its not so bad.
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Yep. This is why I want to stick with the DRV8301 for this design. If nothing else, hand soldering is still possible
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Looking pretty good so far under a locked-rotor load. I still get the OC faults when changing currents under load too quickly, I’ll try out a few other things to see if I can reduce their incidence. It does look like the DRV is losing its mind, I need to reset the CF2 when it throws the faults to get it to operate properly again. Perhaps it would be possible to retransmit the default settings whenever a fault code is sent, so even if it loses it’s settings it can return to operation properly.
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Did you change R64 and R65 to 10k and change the firmware?
I did not. I paid more attention to what shaman was saying about the DRV losing it’s memory values and reseting the CF2 every time I got a fault like the one above. Once I have a fault, the DRV will kinda-sorta operate for a little while after that, but with jerks and faults and other problems that will eventually lead to the failure of the DRV (ask me how I know). Considering this probably includes settings like gate drive current, I decided to try to test a bit more as is. That and I can’t find my 0603 passive assortment. Right now I can test up to about 70A, but I need to get these things permanently screwed down to a heatsink before I go too much farther.
I hope to have a decent oscilloscope in the near future, I’d like to know what exactly is causing the DRV to lose its mind so I can perhaps find a way to attenuate the noise somewhat. It’s clear that there’s some EMI problem - I’ve seen similar problems with micros in high dv/dt environments before, but I’m curious as to where it’s coming from.
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Yes this is only happening at low rpm / high current. I found that with some motors like the KEDA 6364 the problem is much worse (low inducatance?). Other than that the Focers v2 are really running well. I did not manage to destroy a DRV chip on them so far.
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Uh oh! I’m planning on hooking up two CFOC2’s on my Keda 6364 motors tomorrow. You got any advice for me?
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Ah, low rpm and high current makes sense. As this is a hub motor, my maxed out RPM on 36V is only 400RPM. Even with 10 pole pairs I’m barely breaking 4k erpm. This is a 12/12 slot, 20 pole motor.
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I could almost eliminate the problem on my mountainbard by turning on HFI. When i had them on my longboard(no hfi) i always had to push start. Also smart reverse triggers the problem almost immediatly.
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I found this yesterday. They bring up the issue with the DRV internal control registers to be reset with an example.
Here is a quote from page 12
”The possible reason for this is the DRV8301 DVDD voltage is collapsing suddenly, or big motor phase current circling generates large EMI, and then causing a RESET for DRV8301 internal registers in very short time. If the decoupling for DVDD, AVDD, GVDD, and PVDD is not done properly, then the device may be reset when the supplies drop during heavy load conditions… like high current or braking.”
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Two questions… what’s “HFI”?
And were your motors sensored? I could never get anything remotely like a good start with my Keda 6364’s on a VESC 4.12 until I added Hall sensors.
No they were not sensored, it should work much better with sensors. HFI is a sensorless alternative to sensors.
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Sensored or sensorless operation for your bench testing?
Thanks for finding this! I’ll take a look at the suggestions in this note and see if I can make some improvements on v1.0
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It’s good to finally get some technical feedback here. This will for sure lead to a stronger product with v1.0
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Also, I’ve added in some filters for the hall sensors. I’ve read reports of this helping with low-rpm high-current situations when using sensors. Makes sense if the motor is inducing a lot of noise into the hall sensor signals when high current is flowing
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I’m running sensorless, mostly because I’m too lazy to hook up the halls. When I get my crimpers and connectors I’ll make a pigtail to connect the hall sensors too and see if that helps.
Edit: I just realised I haven’t played with HFI yet. Time to mess around with that!
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I can tell you on my Keda 6364’s adding sensors made a world of difference. I don’t plan to run any motor sensorless going forward.
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Just tried HFI. I get the tone and such perfectly well, but it turns out my motor’s inductance is too high for the voltage range of the CF2 to properly use HFI to do position sensing. Oh well!
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Let me know when you try the sensors!
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