DRV8302 faults with FOC

Discussions regarding the Field Oriented Control (FOC) implementation on the VESC.
Marcel
Posts: 5
Joined: 22 Jan 2016, 09:45

Re: DRV8302 faults with FOC

Postby Marcel » 28 Jan 2016, 13:24

I added the second capacitor and now the motor is running smoothlier ! Thanks !

hexakopter
Posts: 86
Joined: 24 Dec 2015, 15:24
Location: Germany

Re: DRV8302 faults with FOC

Postby hexakopter » 28 Jan 2016, 15:43

I think that is a lot of positive feedback to the DRV fix. So I think one should definitely use a 4.7uF Capacitor for C18 when soldering new PCBs.
I dont understand arvidb's message completely. Should it maybe be more than 4.7uF needed to work best?

whitepony
Posts: 38
Joined: 02 Jan 2016, 19:57
Location: Germany

Re: DRV8302 faults with FOC

Postby whitepony » 28 Jan 2016, 17:50

while bench and living room tests work quite well, I had issues outside today. sun was shining, so I gave it a go - I could usually drive well for a few hundred meters, but after a while I started to have suddenly quite high delay of nunchuck -> vesc -> wheel. sometimes it even felt like random wheel acceleration, sometimes really just by 2-3 seconds delayed. I had my laptop with me and tried to connect to the vesc in those moments: it wasnt possible, told me something like "serial port error (2)" or something similar. when I cut the power and started over, it was all fine again - could connect and it would respond normal to nunchuck throttle.

ended up switching back to BLCD for now! :?

arvidb
Posts: 206
Joined: 26 Dec 2015, 14:38
Location: Sweden, Stockholm

Re: DRV8302 faults with FOC

Postby arvidb » 29 Jan 2016, 02:22

hexakopter wrote:I dont understand arvidb's message completely. Should it maybe be more than 4.7uF needed to work best?

I don't understand this completely either. :) More on this in the DRV Fault GVDD thread.

Mk32784
Posts: 9
Joined: 08 May 2017, 11:11

Re: DRV8302 faults with FOC

Postby Mk32784 » 13 May 2017, 08:45

Just got a VESC and have this problem on FOC. Can't even pass the detection.

The link someone posted for the part seems dead, does anyone have an updated link where to get this capacitor? (i didn't build this board)

rpn314
Posts: 3
Joined: 08 Oct 2016, 22:46

Re: DRV8302 faults with FOC

Postby rpn314 » 04 Jul 2017, 16:43

Mk32784 wrote:Just got a VESC and have this problem on FOC. Can't even pass the detection.

The link someone posted for the part seems dead, does anyone have an updated link where to get this capacitor? (i didn't build this board)


Way to resurrect a very old thread ;)

The link still works for me, however the part is now obsolete (no longer made). I believe this one is a suitable replacement: 810-C1608X5R1C225K-4.

Your description of the issue you're seeing is quite vague however, so I'm not sure if this will actually fix your issue.

Cubic
Posts: 1
Joined: 02 Dec 2017, 18:08
Location: Cuijk, Netherlands

Re: DRV8302 faults with FOC

Postby Cubic » 02 Dec 2017, 18:27

As we say: better late than not at all. Maybe this can explain what is going on. Multilayer ceramic capacitors actually change in value depending on the voltage applied. Please find the top right graph in the attachment. It shows that the capacitance reduces by 80%. So you installed 1uF? Oh, no, when voltage applied it now is just 220nF.
I did not know this until a few weeks ago. I do this work for just some 30-odd years. For this function either use an abundance of ceramic caps, also in different values to have the dip in the ESR in a range of frequencies, or use foil capacitors.
Just so you know.

Cubic.
Attachments
C5750X7T2E225M250KE.pdf
(239.13 KiB) Downloaded 16 times

ThierryGTLTS
Posts: 80
Joined: 09 Aug 2017, 11:10

Re: DRV8302 faults with FOC

Postby ThierryGTLTS » 03 Dec 2017, 12:24

Yes it's only true for MLCC capacitors.

GOG or NPO are the best, but you can only find them in low values.
Most of the time X8R, X7R, or X7S are far better than Z5U or Y5V.

But even X7R (very common) are not always very good.

So you have to find the "value vs DC voltage" (called DC bias) of you cap.
A good MURATA tool can be found here http://ds2.murata.co.jp/simsurfing/index.html?lcid=en-us
Other manufacturers have also these datas available.

Have a Nice Day.

Thierry

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Ecyclist
Posts: 28
Joined: 24 Jun 2017, 01:26
Location: San Diego, CA

Re: DRV8302 faults with FOC

Postby Ecyclist » 08 Jan 2018, 18:06

At this point I haven't used FOC in my setup. From what I read, with FOC, a motor will be more efficient and quieter. Is adding extra capacitor on top of the existing one or changing to larger capacitor the way to go? If a larger capacitor is a good option for a new build, which one is the best for the job?
I'm asking because, from what you guys write, this is not clear. My ebike has no problems running on BLDC; however I would like to go one step up with FOC, but only with no problems.

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TheFallen
Posts: 67
Joined: 26 Oct 2016, 10:49
Location: UK
Contact:

Re: DRV8302 faults with FOC

Postby TheFallen » 09 Jan 2018, 09:13

Providing you've bought a recent VESC it'll probably have the required capacitance already fitted.


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