High Power VESC

Discuss hardware related to the VESC such as the NRF nunchuk.
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TheFallen
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Re: High Power VESC

Postby TheFallen » 17 Dec 2016, 21:14


arvidb
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Re: High Power VESC

Postby arvidb » 18 Dec 2016, 11:39

That paper (Selecting Film Bus Link Capacitors For High Performance Inverter Applications) can be found in PDF format, for free.

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TheFallen
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Re: High Power VESC

Postby TheFallen » 22 Dec 2016, 10:35

The capacitors arrived: Image

They are B32524Q1226K from EPCOS, 22uF 100Vdc Polyester Film Capacitor. Bananas for scale as the capacitors are large, 14.0mm × 24.5mm × 31.5mm so fitting them into my enclosure was proving difficult.

Image

But eventually I found an arrangement that would work. I know it's not the optimal arrangement but it will suffice for version 1.

Image

Frustratingly while I was trying to get it all packaged up one of the wires broke off of one of my ACSxxx current sensors.

Image

I'm off travelling for the holidays so won't be able to fix the pin or start powering it up, that will have to wait for early next year. In the mean time I'm planning version 2 of the power and logic boards as well as getting the code changed and re-compiled.

Merry Christmas!

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TheFallen
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Re: High Power VESC

Postby TheFallen » 09 Jan 2017, 23:25

Back for Christmas/New Years.

Desoldered the ACSxxx from the bus bars, wow, 100W soldering irons are great! Soldered the new one one fairly easily too!
Image

And then added the wires:
Image

Going to try and be more careful this time with the wires to avoid this happening. As I don't have a carrier PCB for the ACSxxxs this is always a danger.

It took me the whole of Sunday to install Eclipse, Cygwin, GCC/GBD/G++ and get them all playing nicely together but it can compile the VESC git repo now. I just have to make my changes (invert current gain, increase the dead time) re-compile and upload.

Of course considering that this is quite an investment of time, effort and money I'm rather weary of switching it on. I'll try and build up the necessary courage soon!

Now this design, Issue A, is only a prototype, a way of proving that the DRV8302 is not required and with suitable gate drivers much larger MOSFETs capable of handling greater power can be controlled. Hopefully once this is proved I can move on to Issue B which will be designed to be more robust and easier to manufacture. A CAD of it is below:
Image

As before the logic is on a separate, standard 2 layer 1oz PCB while the power stage is on a 2 layer >2oz PCB with added copper bus bars. This should help keep costs down.

arvidb
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Re: High Power VESC

Postby arvidb » 10 Jan 2017, 20:24

Very interesting with the Polyester Film Capacitors. What's your design targets (switching frequency, phase load inductance, bus link capacitor ripple voltage percentage)?

I feel your pain with the ACS broken leg. :( Good thing that you had that 100 W iron! :)

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TheFallen
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Re: High Power VESC

Postby TheFallen » 10 Jan 2017, 23:44


lizardmech
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Re: High Power VESC

Postby lizardmech » 11 Jan 2017, 04:53

Interested to see if this works, having drivers located away from the fets goes against ever application note and datasheet I have read, but that is for PCBs I haven't seen anything on using twisted wire pairs. I don't know about the ACS sensors, when I built my board without a drv8302 I tried them on the first few designs but never got it working until I switched back to shunt based sensing.

Where is the current sense code located? I keep looking for it but can't make much sense of it.

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TheFallen
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Re: High Power VESC

Postby TheFallen » 11 Jan 2017, 08:53


lizardmech
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Re: High Power VESC

Postby lizardmech » 11 Jan 2017, 11:37


rew
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Re: High Power VESC

Postby rew » 13 Jan 2017, 11:50



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