High Power VESC

Discuss hardware related to the VESC such as the NRF nunchuk.
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TheFallen
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Joined: 26 Oct 2016, 10:49
Location: UK
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Re: High Power VESC

Postby TheFallen » 09 Jan 2018, 19:38

Whey! Time for an update!

So to combat the distance between the MOSFET gates and gate drivers I've designed a gate driver shim. Its a small PCB that puts the gate driver chips (UCC27211DDA) as close to the MOSFET gates as possible. The board is designed to fit on my IMS power stages I've mentioned here: viewtopic.php?f=15&t=505&start=50#p4330

I ordered them over the Christmas break and they turned up today:
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OSHPark are amazing. Also, free jellybeans! The boards are 2 layer, 1 oz, 120mm x 25mm x 1.6mm PCBs. Cost $23 for 3.

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I immediately started populating the passives whilst at work and I put the parts order in today. Thanks to work for their regular orders the parts should turn up tomorrow and I can finish soldering the boards and get them tested.

The largest change is the addition of a much much larger bootstrap capacitor on the gate drivers. Increased from 100nF to 4.7uF. I've also included the current sense amplifiers on the board. In theory this could be attached to an STM Nucleo development board for a working VESC-alike. Of course after they were manufactured I noticed I'd forgotten one thing, the phase voltage sense connections. *sigh*

User avatar
TheFallen
Posts: 70
Joined: 26 Oct 2016, 10:49
Location: UK
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Re: High Power VESC

Postby TheFallen » 13 Feb 2018, 07:32

Got round to playing with my driver shim last night!

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Here I've got one channel of the shim connected up to a Arduino Due toggling HI and LI at 2kHz. The MOSFETs are hooked up to a +32.7V current limited supply and have no load. I'm supplying the UCC27211s with +12V from the second channel of the power supply.

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This is the rise and fall of the unloaded output overlayed, Rigol scopes seem to have a rather neat feature here. The scope is reporting that it takes ~30ns for a 10% to 90% rise or fall.

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In this image I've now got the drive signals for the high side gate and low side gate. I understand there will be some noise as I'm attaching long antennas onto them and it's not ideal but it ought to help. The purple trace is the high side gate, the yellow trace is the low side gate with the blue remaining the output. In both cases The output seems to be okay but I'm keen for others opinions.

Tonight I'm hoping to solder together a small load and to start looking at the output of the AD8418.


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